Musculoskeletal phenotype through the life course: the role of nutrition.

PubMed

Ward, Kate

2012-02-01

This review considers the definition of a healthy bone phenotype through the life course and the modulating effects of muscle function and nutrition. In particular, it will emphasise that optimal bone strength (and how that is regulated) is more important than simple measures of bone mass. The forces imposed on bone by muscle loading are the primary determinants of musculoskeletal health. Any factor that changes muscle loading on the bone, or the response of bone to loading results in alterations of bone strength. Advances in technology have enhanced the understanding of a healthy bone phenotype in different skeletal compartments. Multiple components of muscle strength can also be quantified. The critical evaluation of emerging technologies for assessment of bone and muscle phenotype is vital. Populations with low and moderate/high daily Ca intakes and/or different vitamin D status illustrate the importance of nutrition in determining musculoskeletal phenotype. Changes in mass and architecture maintain strength despite low Ca intake or vitamin D status. There is a complex interaction between body fat and bone which, in addition to protein intake, is emerging as a key area of research. Muscle and bone should be considered as an integrative unit; the role of body fat requires definition. There remains a lack of longitudinal evidence to understand how nutrition and lifestyle define musculoskeletal health. In conclusion, a life-course approach is required to understand the definition of healthy skeletal phenotype in different populations and at different stages of life.

Effects of Exercise on Bone Status in Female Subjects, from Young Girls to Postmenopausal Women: An Overview of Systematic Reviews and Meta-Analyses.

PubMed

Xu, Jincheng; Lombardi, Giovanni; Jiao, Wei; Banfi, Giuseppe

2016-08-01

Osteoporosis and postmenopausal bone loss pose a huge social and economic burden worldwide. Regular exercise and physical activity are effective interventions for maximizing or maintaining peak bone mass and preventing bone loss in the elderly; however, most recommendations are addressed to the general public and lack specific indications for girls and women, the segment of the population most at risk for developing osteoporosis. The aim of this overview of systematic reviews and meta-analyses was to summarize current evidence for the effects of exercise and physical activity interventions on bone status in girls and women, and to explore whether specific exercise programs exist for improving or maintaining bone mass or bone strength in females. The PubMed, EMBASE, PEDro, and Cochrane Library databases were searched from January 2009, updated to 22 June 2015, using the following groups of search terms: (i) 'physical activity' and 'exercise'; and (ii) 'bone', 'bone health', 'bone strength', 'bone structure', 'bone metabolism', 'bone turnover', and 'bone biomarkers'. Searches and screening were limited to systematic reviews or meta-analyses of studies in females and published in English. Our final analysis included 12 articles that met the inclusion criteria. Combined-impact exercise protocols (impact exercise with resistance training) are the best choice to preserve/improve bone mineral density in pre- and postmenopausal women. Peak bone mass in young girls can be improved with short bouts of school-based high-impact plyometric exercise programs. Whole-body vibration exercises have no beneficial effects on bone in postmenopausal or elderly women. Lifelong exercise, specific for age, is an effective way to sustain bone health in girls and women.

Age-related Changes in the Fracture Resistance of Male Fischer F344 Rat Bone

PubMed Central

Uppuganti, Sasidhar; Granke, Mathilde; Makowski, Alexander J.; Does, Mark D.; Nyman, Jeffry S.

2015-01-01

In addition to the loss in bone volume that occurs with age, there is a decline in material properties. To test new therapies or diagnostic tools that target such properties as material strength and toughness, a pre-clinical model of aging would be useful in which changes in bone are similar to those that occur with aging in humans. Toward that end, we hypothesized that similar to human bone, the estimated toughness and material strength of cortical bone at the apparent-level decreases with age in the male Fischer F344 rat. In addition, we tested whether the known decline in trabecular architecture in rats translated to an age-related decrease in vertebra (VB) strength and whether non-X-ray techniques could quantify tissue changes at micron and sub-micron length scales. Bones were harvested from 6-, 12-, and 24-month (mo.) old rats (n=12 per age). Despite a loss in trabecular bone with age, VB compressive strength was similar among the age groups. Similarly, whole-bone strength (peak force) in bending was maintained (femur) or increased (radius) with aging. There was though an age-related decrease in post-yield toughness (radius) and bending strength (femur). The ability to resist crack initiation was actually higher for the 12-mo. and 24-mo. than for 6-mo. rats (notch femur), but the estimated work to propagate the crack was less for the aged bone. For the femur diaphysis region, porosity increased while bound water decreased with age. For the radius diaphysis, there was an age-related increase in non-enzymatic and mature enzymatic collagen crosslinks. Both Raman spectroscopy and reference point indentation detected differences in tissue properties with age, though the trends did not necessarily match observations from human tissue. PMID:26610688

Age-related changes in the fracture resistance of male Fischer F344 rat bone.

PubMed

Uppuganti, Sasidhar; Granke, Mathilde; Makowski, Alexander J; Does, Mark D; Nyman, Jeffry S

2016-02-01

In addition to the loss in bone volume that occurs with age, there is a decline in material properties. To test new therapies or diagnostic tools that target such properties as material strength and toughness, a pre-clinical model of aging would be useful in which changes in bone are similar to those that occur with aging in humans. Toward that end, we hypothesized that similar to human bone, the estimated toughness and material strength of cortical bone at the apparent-level decreases with age in the male Fischer F344 rat. In addition, we tested whether the known decline in trabecular architecture in rats translated to an age-related decrease in vertebra (VB) strength and whether non-X-ray techniques could quantify tissue changes at micron and sub-micron length scales. Bones were harvested from 6-, 12-, and 24-month (mo.) old rats (n=12 per age). Despite a loss in trabecular bone with age, VB compressive strength was similar among the age groups. Similarly, whole-bone strength (peak force) in bending was maintained (femur) or increased (radius) with aging. There was though an age-related decrease in post-yield toughness (radius) and bending strength (femur). The ability to resist crack initiation was actually higher for the 12-mo. and 24-mo. than for 6-mo. rats (notch femur), but the estimated work to propagate the crack was less for the aged bone. For the femur diaphysis region, porosity increased while bound water decreased with age. For the radius diaphysis, there was an age-related increase in non-enzymatic and mature enzymatic collagen crosslinks. Raman spectroscopy analysis of embedded cross-sections of the tibia mid-shaft detected an increase in carbonate subsitution with advanced aging for both inner and outer tissue. Published by Elsevier Inc.

Insights into material and structural basis of bone fragility from diseases associated with fractures: how determinants of the biomechanical properties of bone are compromised by disease.

PubMed

Chavassieux, P; Seeman, E; Delmas, P D

2007-04-01

Minimal trauma fractures in bone diseases are the result of bone fragility. Rather than considering bone fragility as being the result of a reduced amount of bone, we recognize that bone fragility is the result of changes in the material and structural properties of bone. A better understanding of the contribution of each component of the material composition and structure and how these interact to maintain whole bone strength is obtained by the study of metabolic bone diseases. Disorders of collagen (osteogenesis imperfecta and Paget's disease of bone), mineral content, composition and distribution (fluorosis and osteomalacia); diseases of high remodeling (postmenopausal osteoporosis, hyperparathyroidism, and hyperthyroidism) and low remodeling (osteopetrosis, pycnodysostosis); and other diseases (idiopathic male osteoporosis, corticosteroid-induced osteoporosis) produce abnormalities in the material composition and structure that lead to bone fragility. Observations in patients and in animal models provide insights on the biomechanical consequences of these illnesses and the nature of the qualities of bone that determine its strength.

Design variables for mechanical properties of bone tissue scaffolds.

PubMed

Howk, Daniel; Chu, Tien-Min G

2006-01-01

The reconstruction of segmental defect in long bone is a clinical challenge. Multiple surgeries are typically required to restore the structure and function of the affected defect site. In order to overcome this defect a biodegradable bone tissue engineering scaffold is used. This scaffold acts as a carrier of proteins and growth factors, while also supporting the load that the bone would normally sustain, until the natural bone can regenerate in its place. Work was done to optimize an existing solid free-form scaffold design. The goal of the optimization was to increase the porosity of the scaffold while maintaining the strength of a previously-tested prototype design. With this in mind, eight new designs were created. These designs were drawn using CAD software and then through the use of finite element analysis the theoretical ultimate compressive strength of each design was obtained. Each scaffold design was constructed by casting a thermal-curable poly(propylene fumarate)/tricalcium phosphate (PPF/TCP) suspension into wax molds fabricated on inkjet printing rapid prototyping machine. The constructs were then experimentally tested by applying a uniaxial compressive load. The theoretical and experimental values of ultimate compressive strength and specific strength of each design were compared. Theoretically, the best scaffold design produced from this work improved upon the current design by increasing the porosity by 46% and also increasing the ultimate compressive strength by 27%. The experimental data was found to match the theoretical strength in four designs, but deviate from the theoretical strength in five designs. The reasons for the deviations and their relation to the rapid prototyping manufacturing technique were discussed. The results of this work show that it is possible to increase the porosity and strength of a bone tissue engineering scaffold through simple iterations in architectural design.

Grizzly bears (Ursus arctos horribilis) and black bears (Ursus americanus) prevent trabecular bone loss during disuse (hibernation).

PubMed

McGee-Lawrence, Meghan E; Wojda, Samantha J; Barlow, Lindsay N; Drummer, Thomas D; Castillo, Alesha B; Kennedy, Oran; Condon, Keith W; Auger, Janene; Black, Hal L; Nelson, O Lynne; Robbins, Charles T; Donahue, Seth W

2009-12-01

Disuse typically causes an imbalance in bone formation and bone resorption, leading to losses of cortical and trabecular bone. In contrast, bears maintain balanced intracortical remodeling and prevent cortical bone loss during disuse (hibernation). Trabecular bone, however, is more detrimentally affected than cortical bone in other animal models of disuse. Here we investigated the effects of hibernation on bone remodeling, architectural properties, and mineral density of grizzly bear (Ursus arctos horribilis) and black bear (Ursus americanus) trabecular bone in several skeletal locations. There were no differences in bone volume fraction or tissue mineral density between hibernating and active bears or between pre- and post-hibernation bears in the ilium, distal femur, or calcaneus. Though indices of cellular activity level (mineral apposition rate, osteoid thickness) decreased, trabecular bone resorption and formation indices remained balanced in hibernating grizzly bears. These data suggest that bears prevent bone loss during disuse by maintaining a balance between bone formation and bone resorption, which consequently preserves bone structure and strength. Further investigation of bone metabolism in hibernating bears may lead to the translation of mechanisms preventing disuse-induced bone loss in bears into novel treatments for osteoporosis.

Grizzly bears (Ursus arctos horribilis) and black bears (Ursus americanus) prevent trabecular bone loss during disuse (hibernation)

PubMed Central

McGee-Lawrence, Meghan E.; Wojda, Samantha J.; Barlow, Lindsay N.; Drummer, Thomas D.; Castillo, Alesha B.; Kennedy, Oran; Condon, Keith W.; Auger, Janene; Black, Hal L.; Nelson, O. Lynne; Robbins, Charles T.; Donahue, Seth W.

2009-01-01

Disuse typically causes an imbalance in bone formation and bone resorption, leading to losses of cortical and trabecular bone. In contrast, bears maintain balanced intracortical remodeling and prevent cortical bone loss during disuse (hibernation). Trabecular bone, however, is more detrimentally affected than cortical bone in other animal models of disuse. Here we investigated the effects of hibernation on bone remodeling, architectural properties, and mineral density of grizzly bear (Ursus arctos horribilis) and black bear (Ursus americanus) trabecular bone in several skeletal locations. There were no differences in bone volume fraction or tissue mineral density between hibernating and active bears or between pre- and post-hibernation bears in the ilium, distal femur, or calcaneus. Though indices of cellular activity level (mineral apposition rate, osteoid thickness) decreased, trabecular bone resorption and formation indices remained balanced in hibernating grizzly bears. These data suggest that bears prevent bone loss during disuse by maintaining a balance between bone formation and bone resorption, which consequently preserves bone structure and strength. Further investigation of bone metabolism in hibernating bears may lead to the translation of mechanisms preventing disuse induced bone loss in bears into novel treatments for osteoporosis. PMID:19703606

Changes in chemical composition of bone matrix in ovariectomized (OVX) rats detected by Raman spectroscopy and multivariate analysis

NASA Astrophysics Data System (ADS)

Oshima, Yusuke; Iimura, Tadahiro; Saitou, Takashi; Imamura, Takeshi

2015-02-01

Osteoporosis is a major bone disease that connotes the risk of fragility fractures resulting from alterations to bone quantity and/or quality to mechanical competence. Bone strength arises from both bone quantity and quality. Assessment of bone quality and bone quantity is important for prediction of fracture risk. In spite of the two factors contribute to maintain the bone strength, only one factor, bone mineral density is used to determine the bone strength in the current diagnosis of osteoporosis. On the other hand, there is no practical method to measure chemical composition of bone tissue including hydroxyapatite and collagen non-invasively. Raman spectroscopy is a powerful technique to analyze chemical composition and material properties of bone matrix non-invasively. Here we demonstrated Raman spectroscopic analysis of the bone matrix in osteoporosis model rat. Ovariectomized (OVX) rat was made and the decalcified sections of tibias were analyzed by a Raman microscope. In the results, Raman bands of typical collagen appeared in the obtained spectra. Although the typical mineral bands at 960 cm-1 (Phosphate) was absent due to decalcified processing, we found that Raman peak intensities of amide I and C-C stretching bands were significantly different between OVX and sham-operated specimens. These differences on the Raman spectra were statistically compared by multivariate analyses, principal component analysis (PCA) and liner discrimination analysis (LDA). Our analyses suggest that amide I and C-C stretching bands can be related to stability of bone matrix which reflects bone quality.

Exploring the Bone Proteome to Help Explain Altered Bone Remodeling and Preservation of Bone Architecture and Strength in Hibernating Marmots.

PubMed

Doherty, Alison H; Roteliuk, Danielle M; Gookin, Sara E; McGrew, Ashley K; Broccardo, Carolyn J; Condon, Keith W; Prenni, Jessica E; Wojda, Samantha J; Florant, Gregory L; Donahue, Seth W

2016-01-01

Periods of physical inactivity increase bone resorption and cause bone loss and increased fracture risk. However, hibernating bears, marmots, and woodchucks maintain bone structure and strength, despite being physically inactive for prolonged periods annually. We tested the hypothesis that bone turnover rates would decrease and bone structural and mechanical properties would be preserved in hibernating marmots (Marmota flaviventris). Femurs and tibias were collected from marmots during hibernation and in the summer following hibernation. Bone remodeling was significantly altered in cortical and trabecular bone during hibernation with suppressed formation and no change in resorption, unlike the increased bone resorption that occurs during disuse in humans and other animals. Trabecular bone architecture and cortical bone geometrical and mechanical properties were not different between hibernating and active marmots, but bone marrow adiposity was significantly greater in hibernators. Of the 506 proteins identified in marmot bone, 40 were significantly different in abundance between active and hibernating marmots. Monoaglycerol lipase, which plays an important role in fatty acid metabolism and the endocannabinoid system, was 98-fold higher in hibernating marmots compared with summer marmots and may play a role in regulating the changes in bone and fat metabolism that occur during hibernation.

Mechanical Contributions of the Cortical and Trabecular Compartments Contribute to Differences in Age-Related Changes in Vertebral Body Strength in Men and Women Assessed by QCT-Based Finite Element Analysis

PubMed Central

Christiansen, Blaine A; Kopperdahl, David L; Kiel, Douglas P; Keaveny, Tony M; Bouxsein, Mary L

2011-01-01

The biomechanical mechanisms underlying sex-specific differences in age-related vertebral fracture rates are ill defined. To gain insight into this issue, we used finite element analysis of clinical computed tomography (CT) scans of the vertebral bodies of L3 and T10 of young and old men and women to assess age- and sex-related differences in the strength of the whole vertebra, the trabecular compartment, and the peripheral compartment (the outer 2 mm of vertebral bone, including the thin cortical shell). We sought to determine whether structural and geometric changes with age differ in men and women, making women more susceptible to vertebral fractures. As expected, we found that vertebral strength decreased with age 2-fold more in women than in men. The strength of the trabecular compartment declined significantly with age for both sexes, whereas the strength of the peripheral compartment decreased with age in women but was largely maintained in men. The proportion of mechanical strength attributable to the peripheral compartment increased with age in both sexes and at both vertebral levels. Taken together, these results indicate that men and women lose vertebral bone differently with age, particularly in the peripheral (cortical) compartment. This differential bone loss explains, in part, a greater decline in bone strength in women and may contribute to the higher incidence of vertebral fractures among women than men. © 2011 American Society for Bone and Mineral Research. PMID:21542000

The purinergic receptor P2X5 regulates inflammasome activity and hyper-multinucleation of murine osteoclasts

DOE PAGES

Kim, Hyunsoo; Walsh, Matthew C.; Takegahara, Noriko; ...

2017-03-15

Excessive bone resorption by osteoclasts (OCs) can result in serious clinical outcomes, including bone loss that may weaken skeletal or periodontal strength. Proper bone homeostasis and skeletal strength are maintained by balancing OC function with the bone-forming function of osteoblasts. Unfortunately, current treatments that broadly inhibit OC differentiation or function may also interfere with coupled bone formation. We therefore identified a factor, the purinergic receptor P2X5 that is highly expressed during the OC maturation phase, and which we show here plays no apparent role in early bone development and homeostasis, but which is required for osteoclast-mediated inflammatory bone loss andmore » hyper-multinucleation of OCs. We further demonstrate that P2X5 is required for ATP-mediated inflammasome activation and IL-1β production by OCs, and that P2X5-deficient OC maturation is rescued in vitro by addition of exogenous IL-1β. These findings identify a mechanism by which OCs react to inflammatory stimuli, and may identify purinergic signaling as a therapeutic target for bone loss related inflammatory conditions.« less

The purinergic receptor P2X5 regulates inflammasome activity and hyper-multinucleation of murine osteoclasts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Hyunsoo; Walsh, Matthew C.; Takegahara, Noriko

Excessive bone resorption by osteoclasts (OCs) can result in serious clinical outcomes, including bone loss that may weaken skeletal or periodontal strength. Proper bone homeostasis and skeletal strength are maintained by balancing OC function with the bone-forming function of osteoblasts. Unfortunately, current treatments that broadly inhibit OC differentiation or function may also interfere with coupled bone formation. We therefore identified a factor, the purinergic receptor P2X5 that is highly expressed during the OC maturation phase, and which we show here plays no apparent role in early bone development and homeostasis, but which is required for osteoclast-mediated inflammatory bone loss andmore » hyper-multinucleation of OCs. We further demonstrate that P2X5 is required for ATP-mediated inflammasome activation and IL-1β production by OCs, and that P2X5-deficient OC maturation is rescued in vitro by addition of exogenous IL-1β. These findings identify a mechanism by which OCs react to inflammatory stimuli, and may identify purinergic signaling as a therapeutic target for bone loss related inflammatory conditions.« less

Clec11a/osteolectin is an osteogenic growth factor that promotes the maintenance of the adult skeleton

PubMed Central

Yue, Rui; Shen, Bo; Morrison, Sean J

2016-01-01

Bone marrow stromal cells maintain the adult skeleton by forming osteoblasts throughout life that regenerate bone and repair fractures. We discovered that subsets of these stromal cells, osteoblasts, osteocytes, and hypertrophic chondrocytes secrete a C-type lectin domain protein, Clec11a, which promotes osteogenesis. Clec11a-deficient mice appeared developmentally normal and had normal hematopoiesis but reduced limb and vertebral bone. Clec11a-deficient mice exhibited accelerated bone loss during aging, reduced bone strength, and delayed fracture healing. Bone marrow stromal cells from Clec11a-deficient mice showed impaired osteogenic differentiation, but normal adipogenic and chondrogenic differentiation. Recombinant Clec11a promoted osteogenesis by stromal cells in culture and increased bone mass in osteoporotic mice in vivo. Recombinant human Clec11a promoted osteogenesis by human bone marrow stromal cells in culture and in vivo. Clec11a thus maintains the adult skeleton by promoting the differentiation of mesenchymal progenitors into mature osteoblasts. In light of this, we propose to call this factor Osteolectin. DOI: http://dx.doi.org/10.7554/eLife.18782.001 PMID:27976999

Hand grip strength and maximum peak expiratory flow: determinants of bone mineral density of adolescent students.

PubMed

Cossio-Bolaños, Marco; Lee-Andruske, Cynthia; de Arruda, Miguel; Luarte-Rocha, Cristian; Almonacid-Fierro, Alejandro; Gómez-Campos, Rossana

2018-03-02

Maintaining and building healthy bones during the lifetime requires a complicated interaction between a number of physiological and lifestyle factors. Our goal of this study was to analyze the association between hand grip strength and the maximum peak expiratory flow with bone mineral density and content in adolescent students. The research team studied 1427 adolescent students of both sexes (750 males and 677 females) between the ages of 11.0 and 18.9 years in the Maule Region of Talca (Chile). Weight, standing height, sitting height, hand grip strength (HGS), and maximum peak expiratory flow (PEF) were measured. Furthermore, bone mineral density (BMD) and total body bone mineral content (BMC) were determined by using the Dual-Energy X-Ray Absorptiometry (DXA). Hand grip strength and PEF were categorized in tertiles (lowest, middle, and highest). Linear regression was performed in steps to analyze the relationship between the variables. Differences between categories were determined through ANOVA. In males, the hand grip strength explained 18-19% of the BMD and 20-23% of the BMC. For the females, the percentage of variation occurred between 12 and 13% of the BMD and 17-18% of the BMC. The variation of PEF for the males was observed as 33% of the BMD and 36% of the BMC. For the females, both the BMD and BMC showed a variation of 19%. The HGS and PEF were divided into three categories (lowest, middle, and highest). In both cases, significant differences occurred in bone density health between the three categories. In conclusion, the HGS and the PEF related positively to the bone density health of both sexes of adolescent students. The adolescents with poor values for hand grip strength and expiratory flow showed reduced values of BMD and BMC for the total body. Furthermore, the PEF had a greater influence on bone density health with respect to the HGS of the adolescents of both sexes.

Systematic evaluation of a tissue-engineered bone for maxillary sinus augmentation in large animal canine model.

PubMed

Wang, Shaoyi; Zhang, Zhiyuan; Xia, Lunguo; Zhao, Jun; Sun, Xiaojuan; Zhang, Xiuli; Ye, Dongxia; Uludağ, Hasan; Jiang, Xinquan

2010-01-01

The objective of this study is to systematically evaluate the effects of a tissue-engineered bone complex for maxillary sinus augmentation in a canine model. Twelve sinus floor augmentation surgeries in 6 animals were performed bilaterally and randomly repaired with the following 3 groups of grafts: group A consisted of tissue-engineered osteoblasts/beta-TCP complex (n=4); group B consisted of beta-TCP alone (n=4); group C consisted of autogenous bone obtained from iliac crest as a positive control (n=4). All dogs had uneventful healings following the surgery. Sequential polychrome fluorescent labeling, maxillofacial CT, microhardness tests, as well as histological and histomorphometric analyses indicated that the tissue-engineered osteoblasts/beta-TCP complex dramatically promoted bone formation and mineralization and maximally maintained the height and volume of elevated maxillary sinus. By comparison, both control groups of beta-TCP or autologous iliac bone showed considerable resorption and replacement by fibrous or fatty tissue. We thus conclude that beta-TCP alone could barely maintain the height and volume of the elevated sinus floor, and that the transplantation of autogenous osteoblasts on beta-TCP could promote earlier bone formation and mineralization, maximally maintain height, volume and increase the compressive strength of augmented maxillary sinus. This tissue engineered bone complex might be a better alternative to autologous bone for the clinical edentulous maxillary sinus augmentation. Copyright (c) 2009 Elsevier Inc. All rights reserved.

Physical performance and life quality in postmenopausal women supplemented with vitamin D: a two-year prospective study

PubMed Central

Gao, Li-hong; Zhu, Wen-jun; Liu, Yu-juan; Gu, Jie-mei; Zhang, Zhen-lin; Wang, Ou; Xing, Xiao-ping; Xu, Ling

2015-01-01

Aim: To investigate the effects of calcium and vitamin D supplementation on bone turnover marker levels, muscle strength and quality of life in postmenopausal Chinese women. Methods: A total of 485 healthy postmenopausal Chinese women (63.44±5.04 years) were enrolled in this open-label, 2-year, prospective, community-based trial. The participants were divided into group A, B, C, which were treated with calcium (600 mg/d) alone, calcium (600 mg/d) and cholecalciferol (800 IU/d) or calcium (600 mg/d) and calcitriol (0.25 μg/d), respectively, for 2 years. Serum levels of 25-hydroxyvitamin D, parathyroid hormone, β-CTX and P1NP were measured, and the muscle strength and quality of life were assessed at baseline and at 12- and 24-month follow-ups. Results: Four hundred and sixty one participants completed this study. Serum levels of 25-hydroxyvitamin D were significantly increased in group C, but not changed in groups A and B at 24-month follow-up. Serum levels of parathyroid hormone, bone turnover marker β-CTX and bone formation marker P1NP were significantly decreased in group C, while serum levels of β-CTX were increased in group A at 24-month follow-up. The participants in group C maintained the grip strength, while those in groups A and B exhibited decreased grip strength at 24-month follow-up. The quality of life for the participants in groups B and C remained consistent, but that in group A was deteriorated at 24-month follow-up. Conclusion: Supplementation with calcitriol and calcium modifies the bone turnover marker levels, and maintains muscle strength and quality of life in postmenopausal Chinese women, whereas supplementation with cholecalciferol and calcium prevents aging-mediated deterioration in quality of life. PMID:26279157

Vegetarian diets and bone status.

PubMed

Tucker, Katherine L

2014-07-01

Osteoporosis is a common chronic condition associated with progressive loss of bone mineral density (BMD) and compromised bone strength, with increasing risk of fracture over time. Vegetarian diets have been shown to contain lower amounts of calcium, vitamin D, vitamin B-12, protein, and n-3 (ω-3) fatty acids, all of which have important roles in maintaining bone health. Although zinc intakes are not necessarily lower quantitatively, they are considerably less bioavailable in vegetarian diets, which suggests the need for even higher intakes to maintain adequate status. At the same time, healthy vegetarian diets tend to contain more of several protective nutrients, including magnesium, potassium, vitamin K, and antioxidant and anti-inflammatory phytonutrients. On balance, there is evidence that vegetarians, and particularly vegans, may be at greater risk of lower BMD and fracture. Attention to potential shortfall nutrients through the careful selection of foods or fortified foods or the use of supplements can help ensure healthy bone status to reduce fracture risk in individuals who adhere to vegetarian diets. © 2014 American Society for Nutrition.

Effects of eight-month treatment with ONO-5334, a cathepsin K inhibitor, on bone metabolism, strength and microstructure in ovariectomized cynomolgus monkeys.

PubMed

Ochi, Yasuo; Yamada, Hiroyuki; Mori, Hiroshi; Nakanishi, Yasutomo; Nishikawa, Satoshi; Kayasuga, Ryoji; Kawada, Naoki; Kunishige, Akiko; Hashimoto, Yasuaki; Tanaka, Makoto; Sugitani, Masafumi; Kawabata, Kazuhito

2014-08-01

This study examined the effect of ONO-5334, a cathepsin K inhibitor, on bone turnover, mineral density (BMD), mechanical strength and microstructure in ovariectomized (OVX) cynomolgus monkeys. Vehicle, ONO-5334 (3, 10 or 30 mg/kg) or alendronate (0.5 mg/kg) was orally administered for eight months to sham- and OVX-operated monkeys. ONO-5334 dose-dependently suppressed OVX-induced increase in bone turnover markers (urinary C-terminal cross-linking telopeptide of type I collagen (CTX) and serum osteocalcin). At the dose of 30 mg/kg, ONO-5334 maintained urinary CTX at nearly zero level and kept serum osteocalcin around the level of the sham animals. Marker levels in the alendronate-treated animals were similar to those in the sham animals throughout the study. ONO-5334 dose-dependently reversed the effect of OVX on vertebral BMD as measured by dual-energy X-ray absorptiometry (DXA) with improvement of bone mechanical strength. Both ONO-5334 and alendronate suppressed OVX-induced changes in vertebral microstructure and turnover state. In the femoral neck, peripheral quantitative computed tomography (pQCT) analysis showed that ONO-5334 increased total and cortical BMD. In particular, ONO-5334 significantly increased cortical BMD with improvement of bone mechanical strength. In microstructural analysis, alendronate suppressed OVX-induced increase in femoral mid-shaft osteonal bone formation rate (BFR) to a level below that recorded in the sham group, whereas ONO-5334 at 30 mg/kg did not suppress periosteal, osteonal and endocortical BFR. This finding supports the significant effect of ONO-5334 on cortical BMD and mechanical strength in the femoral neck. The results of this study suggest that ONO-5334 has good therapeutic potential for the treatment of osteoporosis. Copyright © 2014 Elsevier Inc. All rights reserved.

Knee joint transplantation combined with surgical angiogenesis in rabbits – a new experimental model

PubMed Central

Kremer, Thomas; Giusti, Guilherme; Friedrich, Patricia F.; Willems, Wouter; Bishop, Allen T.; Giessler, Goetz A.

2012-01-01

Summary Purpose We have previously described a means to maintain bone allotransplant viability, without long-term immune modulation, replacing allogenic bone vasculature with autogenous vessels. A rabbit model for whole knee joint transplantation was developed and tested using the same methodology, initially as an autotransplant. Materials/Methods Eight New Zealand White rabbit knee joints were elevated on a popliteal vessel pedicle to evaluate limb viability in a non-survival study. Ten additional joints were elevated and replaced orthotopically in a fashion identical to allotransplantation, obviating only microsurgical repairs and immunosuppression. A superficial inferior epigastric facial (SIEF) flap and a saphenous arteriovenous (AV) bundle were introduced into the femur and tibia respectively, generating a neoangiogenic bone circulation. In allogenic transplantation, this step maintains viability after cessation of immunosuppression. Sixteen weeks later, x-rays, microangiography, histology, histomorphometry and biomechanical analysis were performed. Results Limb viability was preserved in the initial 8 animals. Both soft tissue and bone healing occurred in 10 orthotopic transplants. Surgical angiogenesis from the SIEF flap and AV bundle was always present. Bone and joint viability was maintained, with demonstrable new bone formation. Bone strength was less than the opposite side. Arthrosis and joint contractures were frequent. Conclusion We have developed a rabbit knee joint model and evaluation methods suitable for subsequent studies of whole joint allotransplantation. PMID:22113889

Bone remodelling: its local regulation and the emergence of bone fragility.

PubMed

Martin, T John; Seeman, Ego

2008-10-01

Bone modelling prevents the occurrence of damage by adapting bone structure - and hence bone strength - to its loading circumstances. Bone remodelling removes damage, when it inevitably occurs, in order to maintain bone strength. This cellular machinery is successful during growth, but fails during advancing age because of the development of a negative balance between the volumes of bone resorbed and formed during remodelling by the basic multicellular unit (BMU), high rates of remodelling during midlife in women and late in life in both sexes, and a decline in periosteal bone formation. together resulting in bone loss and structural decay each time a remodelling event occurs. The two steps in remodelling - resorption of a volume of bone by osteoclasts and formation of a comparable volume by osteoblasts - are sequential, but the regulatory events leading to these two fully differentiated functions are not. Reparative remodelling is initiated by damage producing osteocyte apoptosis, which signals the location of damage via the osteocyte canalicular system to endosteal lining cells which forms the canopy of a bone-remodelling compartment (BRC). Within the BRC, local recruitment of osteoblast precursors from the lining cells, the marrow and circulation, direct contact with osteoclast precursors, osteoclastogenesis and molecular cross-talk between precursors, mature cells, cells of the immune system, and products of the resorbed matrix, titrate the birth, work and lifespan of the cells of this multicellular remodelling machinery to either remove or form a net volume of bone appropriate to the mechanical requirements.

Novel, non-steroidal, selective androgen receptor modulators (SARMs) with anabolic activity in bone and muscle and improved safety profile.

PubMed

Rosen, J; Negro-Vilar, A

2002-03-01

A novel approach to the treatment of osteoporosis in men, and possibly women, is the development of selective androgen receptor modulators (SARMs) that can stimulate formation of new bone with substantially diminished proliferative activity in the prostate, as well as reduced virilizing activity in women. Over the last several years, we have developed a program to discover and develop novel, non-steroidal, orally-active selective androgen receptor modulators (SARMs) that provide improved therapeutic benefits and reduce risk and side effects. In recent studies, we have used a skeletally mature orchiectomized (ORX) male rat as an animal model of male hypogonadism for assessing the efficacy of LGD2226, a nonsteroidal, non-aromatizable, and non-5alpha-reducible SARM. We assessed the activity of LGD2226 on bone turnover, bone mass and bone strength, and also evaluated the effects exerted on classic androgen-dependent targets, such as prostate, seminal vesicles and muscle. A substantial loss of bone density was observed in ORX animals, and this loss was prevented by SARMs, as well as standard androgens. Biochemical markers of bone turnover revealed an early increase of bone resorption in androgen-deficient rats that was repressed in ORX animals treated with the oral SARM, LGD2226, during a 4-month treatment period. Differences in architectural properties and bone strength were detected by histomorphometric and mechanical analyses, demonstrating beneficial effects of LGD2226 on bone quality in androgen-deficient rats. Histomorphometric analysis of cortical bone revealed distinct anabolic activity of LGD2226 in periosteal bone. LGD2226 was able to prevent bone loss and maintain bone quality in ORX rats by stimulating bone formation, while also inhibiting bone turnover. LGD2226 also exerted anabolic activity on the levator ani muscle. Taken together, these results suggest that orally-active, non-steroidal SARMs may be useful therapeutics for both muscle and bone in elderly hypogonadal men through their anabolic activities. Since SARMs both prevent bone loss, and also stimulate formation of new bone, they may have significant advantages relative to currently used anti-resorptive therapies. Coupled with their activity in muscle and their ability to maintain or restore libido, they offer new therapeutic approaches for male and female hormone replacement.

Changes of Bone-Related Minerals during Denosumab Administration in Post-Menopausal Osteoporotic Patients.

PubMed

Suzuki, Takako; Nakamura, Yukio; Kato, Hiroyuki

2017-08-13

This retrospective study included 21 patients with primary osteoporosis who were treated with the anti-resorption drug, denosumab. To date, there has been no detailed report on the changes of bone-related minerals after anti-resorption drug therapy. Twenty-one post-menopausal females were retrospectively enrolled. Serum zinc (Zn), magnesium (Mg), iron (Fe), copper (Cu), grip strength, and estimated glomerular filtration rate (eGFR) were examined at one week and 1, 2, 4, 6, 8, 10, and 12 months. Lumbar spine (L1-4) bone mineral density (L-BMD) and bilateral total hip BMD (H-BMD) were examined before and at 4, 8, and 12 months after treatment commencement. Serum Zn tended to decrease at one week and one month, and tended to increase during 10 to 12 months. Serum Cu maintained during zero to eight months, then decreased at 10 and 12 months. Serum Fe gradually increased after four months. Serum Mg sharply increased at one week, then decreased further. Grip strength increased for two months, then slightly decreased and maintained 4 to 12 months. eGFR almost maintained for zero to eight months, then slightly decreased thereafter. L-BMD values significantly increased at eight (5.8%) ( p < 0.01) and 12 months (9.8%) ( p < 0.01). H-BMD increased during the period (at 12 months: 3.7%). These results suggest that at later phases of denosumab therapy, Zn and Fe tended to increase while Mg tended to decrease, all of which are important for bone metabolism. Thus, denosumab might improve Zn and Fe metabolism, and thereby likely increase BMD. Since denosumab may not improve Mg, it is better to obtain Mg supplementation during the therapy.

Fabrication and Physical Evaluation of Gelatin-Coated Carbonate Apatite Foam.

PubMed

Hara, Kanae; Fujisawa, Kenji; Nagai, Hirokazu; Takamaru, Natsumi; Ohe, Go; Tsuru, Kanji; Ishikawa, Kunio; Miyamoto, Youji

2016-08-23

Carbonate apatite (CO₃Ap) foam has gained much attention in recent years because of its ability to rapidly replace bone. However, its mechanical strength is extremely low for clinical use. In this study, to understand the potential of gelatin-reinforced CO₃Ap foam for bone replacement, CO₃Ap foam was reinforced with gelatin and the resulting physical characteristics were evaluated. The mechanical strength increased significantly with the gelatin reinforcement. The compressive strength of gelatin-free CO₃Ap foam was 74 kPa whereas that of the gelatin-reinforced CO₃Ap foam, fabricated using 30 mass % gelatin solution, was approximately 3 MPa. Heat treatment for crosslinking gelatin had little effect on the mechanical strength of the foam. The gelatin-reinforced foam did not maintain its shape when immersed in a saline solution as this promoted swelling of the gelatin; however, in the same conditions, the heat-treated gelatin-reinforced foam proved to be stable. It is concluded, therefore, that heat treatment is the key to the fabrication of stable gelatin-reinforced CO₃Ap foam.

[New methods for the evaluation of bone quality. Bone anabolic agents and bone quality.

PubMed

Yamamoto, Norio; Tsuchiya, Hiroyuki

Teriparatide(TPTD)products that can be used clinically in Japan include a daily subcutaneous injection form produced by genetic engineering and a weekly subcutaneous injectable TPTD acetate form produced by chemical synthesis. Published reports indicate that both forms exhibit excellent antifracture efficacy, and as the only anabolic agents that promote osteogenesis, TPTD products now occupy a prominent position. However, the two forms differ considerably, not only in frequency of administration, but also in mechanism of action. The daily form stimulates osteogenesis and accompanying resorption through more radical high bone turnover, and early in the course of treatment, intracortical porosity and apatite crystallization decrease, while immature collagen crosslinking increases. However, because daily formulations also produce an increase in cortical surface area or cortical thickness, the effects are counterbalanced, and bone strength is maintained. In contrast, the weekly form prioritizes osteogenesis, and by concurrently lowering turnover below pretreatment levels, improves trabecular bone mass and structure, and enhances strength without leading to cortical porosity and other undesirable phenomena. Abaloparatide, a PTHrP(1-34)analog that is homologous with the biologically active site of PTH drugs, is currently under development, and we eagerly anticipate further clarification of the mechanism of action of each formulation on bone.

Bone augmentation using a highly porous PLGA/β-TCP scaffold containing fibroblast growth factor-2.

PubMed

Yoshida, T; Miyaji, H; Otani, K; Inoue, K; Nakane, K; Nishimura, H; Ibara, A; Shimada, A; Ogawa, K; Nishida, E; Sugaya, T; Sun, L; Fugetsu, B; Kawanami, M

2015-04-01

Beta-tricalcium phosphate (β-TCP), a bio-absorbable ceramic, facilitates bone conductivity. We constructed a highly porous three-dimensional scaffold, using β-TCP, for bone tissue engineering and coated it with co-poly lactic acid/glycolic acid (PLGA) to improve the mechanical strength and biological performance. The aim of this study was to examine the effect of implantation of the PLGA/β-TCP scaffold loaded with fibroblast growth factor-2 (FGF-2) on bone augmentation. The β-TCP scaffold was fabricated by the replica method using polyurethane foam, then coated with PLGA. The PLGA/β-TCP scaffold was characterized by scanning electron miscroscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction, compressive testing, cell culture and a subcutaneous implant test. Subsequently, a bone-forming test was performed using 52 rats. The β-TCP scaffold, PLGA-coated scaffold, and β-TCP and PLGA-coated scaffolds loaded with FGF-2, were implanted into rat cranial bone. Histological observations were made at 10 and 35 d postsurgery. SEM and TEM observations showed a thin PLGA layer on the β-TCP particles after coating. High porosity (> 90%) of the scaffold was exhibited after PLGA coating, and the compressive strength of the PLGA/β-TCP scaffold was six-fold greater than that of the noncoated scaffold. Good biocompatibility of the PLGA/β-TCP scaffold was found in the culture and implant tests. Histological samples obtained following implantation of PLGA/β-TCP scaffold loaded with FGF-2 showed significant bone augmentation. The PLGA coating improved the mechanical strength of β-TCP scaffolds while maintaining high porosity and tissue compatibility. PLGA/β-TCP scaffolds, in combination with FGF-2, are bioeffective for bone augmentation. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Preliminary study of the biomechanical behavior and physical characteristics of tantalum (Ta)-coated prostheses.

PubMed

Duan, Yonghong; Liu, Lie; Wang, Ling; Guo, Fei; Li, Haoping; Shi, Lei; Li, Mao; Yin, Dayu; Jiang, Chi; Zhu, Qingsheng

2012-03-01

Use of Ta biomaterials in medicine started in the middle of the last century. The good biocompatibility and chemical stability, and the unique physical characteristics of Ta metal have resulted in many possible developments of Ta biomaterials. In this study, histopathological observation, histomorphometric analysis, scanning electron microscope (SEM) observation, energy-dispersive X-ray spectroscopy (EDX) analysis, biomechanical testing, and examination of the coating's mechanical strength have been used to evaluate the value of clinical application of Ta-coated prostheses prepared by a plasma-spraying process. Histopathological observation has demonstrated that the periprosthetic new bone tissues tightly and stably adhere to the Ta coating after the implantation, with no signs of loosening. Early after implantation, there is no significant difference in periprosthetic bone volume and ultimate shear strength between Ta-coated and Ti-coated prostheses (P > 0.05). EDX analysis suggests that the ultimate shear stress does not damage Ta coating. Mechanical strength testing shows that the adhesive strength and Vicker's surface hardness (HV) of the Ta coating are significantly higher than those of the Ti coating (P < 0.01). Ta coating has good stability and bone biocompatibility; the extraordinary physical characteristics of Ta coating have great significance in maintaining prosthetic stability and surface porosity after implantation.

Role of IGF-I Signaling in Muscle Bone Interactions

PubMed Central

Bikle, Daniel D; Tahimic, Candice; Chang, Wenhan; Wang, Yongmei; Philippou, Anastassios; Barton, Elisabeth R.

2015-01-01

Skeletal muscle and bone rely on a number of growth factors to undergo development, modulate growth, and maintain physiological strength. A major player in these actions is insulin-like growth factor I (IGF-I). However, because this growth factor can directly enhance muscle mass and bone density, it alters the state of the musculoskeletal system indirectly through mechanical crosstalk between these two organ systems. Thus, there are clearly synergistic actions of IGF-I that extend beyond the direct activity through its receptor. This review will cover the production and signaling of IGF-I as it pertains to muscle and bone, the chemical and mechanical influences that arise from IGF-I activity, and the potential for therapeutic strategies based on IGF-I. PMID:26453498

[Adapted physical activity in the prevention and therapy of osteoporosis].

PubMed

Bosković, Ksenija; Gava, Branka Protić; Grajić, Mirko; Madić, Dejan; Obradović, Borislav; Todorović, Snezana Tomasević

2013-01-01

Osteoporosis, a disease characterized by the progressive loss of bone tissue, is one of the most common complications of aging. According to some calculations, there were 25% of women and 4% of men older than 50 years with osteoporosis in the world in 2010. It is assumed that the number of patients with osteoporosis will increase by 30% in every 10 years in the 21st century. There are many reasons for that: the world's population is growing older, diet is getting poorer in vitamins and minerals and physical activity is decreasing. THE QUALITY AND QUANTITY OF BONE TISSUE: Developing bones are much more responsive to mechanical loading and physical activity than mature bones. This suggests that training in early childhood may be an important factor in the prevention of osteoporosis in later life. It is important to note that the quality of bone achieved by training at younger age cannot be maintained permanently if it is not supported by physical activity later in life. Adapted physical activity represents physical activity individually tailored according to the psychosomatic capabilities of a person and the goal to be achieved. It can be applied at any age in order to maintain strong bones and reduce the risk of fracture. Adapted physical activity is different for men and women, for different age, as well as for the individuals. Aerobic exercises, which lead to an acceleration of breathing, increased heart rate and mild perspiration, as well as resistance exercises and exercises against resistance done by stretching elastic bands, for hands, legs and torso have been proven to increase bone density and improve bone strength. Coordination and balance exercises are important in an individual workout program. An explanation of the action of adapted physical activity is the basis for the theory of control and modulation of bone loss, muscle strength, coordination and balance. Physical activity is very effective in reducing sclerostin, which is known to inhibit bone formation. In addition, physical training enhances the levels of insulinlike growth factor, which has a very positive effect on bone formation. The aim of adapted physical activity is to improve bone formation in youngsters, to preserve the bone mass in adults and to prevent the bone loss in the elderly thus reducing the risk of falls and resulting fractures; in other words, to minimize the disability caused by fractures and improve the quality of life.

The effect of weight training on bone mineral density and bone turnover in postmenopausal breast cancer survivors with bone loss: a 24-month randomized controlled trial.

PubMed

Waltman, N L; Twiss, J J; Ott, C D; Gross, G J; Lindsey, A M; Moore, T E; Berg, K; Kupzyk, K

2010-08-01

This study examined whether 24 months of weight training exercises enhanced the effectiveness of risedronate, calcium, and vitamin D in maintaining or improving bone mineral density (BMD) in 223 postmenopausal breast cancer survivors. Subjects who were > or =50% adherent to exercise had no improvement in BMD but were less likely to lose BMD. This study examined whether (1) postmenopausal breast cancer survivors (BCS) with bone loss taking 24 months of risedronate, calcium, and vitamin D had increased bone mineral density (BMD) at the total hip, femoral neck, L1-L4 spine, total radius and 33% radius, and decreased bone turnover; (2) subjects who also participated in strength/weight training (ST) exercises had greater increases in BMD and greater decreases in bone turnover; and (3) subjects who also exercised were more likely to preserve (at least maintain) BMD. Postmenopausal BCS (223) were randomly assigned to exercise plus medication or medication only groups. Both groups received 24 months of 1,200 mg of calcium and 400 IU of vitamin D daily and 35 mg of risedronate weekly, and the exercise group additionally had ST exercises twice weekly. After 24 months, women who took medications without exercising had significant improvements in BMD at the total hip (+1.81%) and spine (+2.85%) and significant decreases in Alkphase B (-8.7%) and serum NTx (-16.7%). Women who also exercised had additional increases in BMD at the femoral neck (+0.29%), total hip (+0.34%), spine (+0.23%), total radius (+0.30%), and additional decreases in Alkphase B (-2.4%) and Serum NTx (-6.5%). Additional changes in BMD and bone turnover with exercise were not significant. Subjects who were > or =50% adherent to exercise were less likely to lose BMD at the total hip (chi-square [1] = 4.66, p = 0.03) and femoral neck (chi-square [1] = 4.63, p = 0.03). Strength/weight training exercises may prevent loss of BMD in postmenopausal BCS at risk for bone loss.

Development of bioactive porous α-TCP/HAp beads for bone tissue engineering.

PubMed

Asaoka, Teruo; Ohtake, Shoji; Furukawa, Katsuko S; Tamura, Akito; Ushida, Takashi

2013-11-01

Porous beads of bioactive ceramics such as hydroxyapatite (HAp) and tribasic calcium phosphate (TCP) are considered a promising scaffold for cultivating bone cells. To realize this, α-TCP/HAp functionally graded porous beads are fabricated with two main purposes: to maintain the function of the scaffold with sufficient strength up to the growth of new bone, and is absorbed completely after the growth. HAp is a bioactive material that has both high strength and strong tissue-adhesive properties, but is not readily absorbed by the human body. On the contrary, α-TCP is highly bioabsorbable, resulting in a scaffold that is absorbed before it is completely replaced by bone. In this study, we produced porous, bead-shaped carriers as scaffolds for osteoblast culture. To control the solubility in vivo, the fabricated beads contained α-TCP at the center and HAp at the surface. Cell adaptability of these beads for bone tissue engineering was confirmed in vitro. It was found that α-TCP/HAp bead carriers exhibit low toxicity in the initial stages of cell seeding and cell adhesion. The presence of HAp in the composite bead form effectively increased ALP activity. In conclusion, it is suggested that these newly developed α-TCP/HAp beads are a promising tool for bone tissue engineering. Copyright © 2013 Wiley Periodicals, Inc.

Changes in physicochemical and biological properties of porcine bone derived hydroxyapatite induced by the incorporation of fluoride

NASA Astrophysics Data System (ADS)

Qiao, Wei; Liu, Quan; Li, Zhipeng; Zhang, Hanqing; Chen, Zhuofan

2017-12-01

As the main inorganic component of xenogenic bone graft material, bone-derived biological apatite (BAp) has been widely used in implant dentistry, oral and maxillofacial surgery and orthopedics. However, BAp produced via calcination of animal bones still suffers from some drawbacks, such as insufficient mechanical strength and inadequate degradation rate, which impede its application. Fluoride is known to play important roles in both physiological and pathological processes of human hard tissues for its double effects on bones and teeth. In order to understand the effects of fluoride on the properties of BAp, as well as the mechanism behind them, porcine bone derived hydroxyapatite (PHAp) was prepared via thermal treatment, which was then fluoride incorporated at a series concentrations of sodium fluoride, and noted as 0.25-FPHAp, 0.50-FPHAp, and 0.75-FPHAp respectively. The physicochemical characteristics of the materials, including crystal morphology, crystallinity, functional groups, elemental composition, compressive strength, porosity and solubility, were then determined. The biological properties, such as protein adsorption and cell attachment, were also evaluated. It was found that the spheroid-like crystals of PHAp were changed into rod-like after fluoride substitution, resulting in a fluoride concentration-dependent increase in compressive strength, as well as a decreased porosity and solubility of the apatite. However, even though the addition of fluoride was demonstrated to enhance protein adsorption and cell attachment of the materials, the most favorable results were intriguingly achieved in FPHAp with the least fluoride content. Collectively, low level of fluoride incorporation is proposed promising for the modification of clinically used BAp based bone substitute materials, because of its being able to maintain a good balance between physicochemical and biological properties of the apatite.

Fixation Strength of Polyetheretherketone Sheath-and-Bullet Device for Soft Tissue Repair in the Foot and Ankle.

PubMed

Christensen, Jay; Fischer, Brian; Nute, Michael; Rizza, Robert

Tendon transfers are often performed in the foot and ankle. Recently, interference screws have been a popular choice owing to their ease of use and fixation strength. Considering the benefits, one disadvantage of such devices is laceration of the soft tissues by the implant threads during placement that potentially weaken the structural integrity of the grafts. A shape memory polyetheretherketone bullet-in-sheath tenodesis device uses circumferential compression, eliminating potential damage from thread rotation and maintaining the soft tissue orientation of the graft. The aim of this study was to determine the pullout strength and failure mode for this device in both a synthetic bone analogue and porcine bone models. Thirteen mature bovine extensor tendons were secured into ten 4.0 × 4.0 × 4.0-cm cubes of 15-pound per cubic foot solid rigid polyurethane foam bone analogue models or 3 porcine femoral condyles using the 5 × 20-mm polyetheretherketone soft tissue anchor. The bullet-in-sheath device demonstrated a mean pullout of 280.84 N in the bone analog models and 419.47 N in the porcine bone models. (p = .001). The bullet-in-sheath design preserved the integrity of the tendon graft, and none of the implants dislodged from their original position. Copyright © 2017 The American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Development of biomimetic nanocomposites as bone extracellular matrix for human osteoblastic cells.

PubMed

Bhowmick, Arundhati; Mitra, Tapas; Gnanamani, Arumugam; Das, Manas; Kundu, Patit Paban

2016-05-05

Here, we have developed biomimetic nanocomposites containing chitosan, poly(vinyl alcohol) and nano-hydroxyapatite-zinc oxide as bone extracellular matrix for human osteoblastic cells and characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction. Scanning electron microscopy images revealed interconnected macroporous structures. Moreover, in this study, the problem related to fabricating a porous composite with good mechanical strength has been resolved by incorporating 5wt% of nano-hydroxyapatite-zinc oxide into chitosan-poly(vinyl alcohol) matrix; the present composite showed high tensile strength (20.25MPa) while maintaining appreciable porosity (65.25%). These values are similar to human cancellous bone. These nanocomposites also showed superior water uptake, antimicrobial and biodegradable properties than the previously reported results. Compatibility with human blood and pH was observed, indicating nontoxicity of these materials to the human body. Moreover, proliferation of osteoblastic MG-63 cells onto the nanocomposites was also observed without having any negative effect. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fabrication and Physical Evaluation of Gelatin-Coated Carbonate Apatite Foam

PubMed Central

Hara, Kanae; Fujisawa, Kenji; Nagai, Hirokazu; Takamaru, Natsumi; Ohe, Go; Tsuru, Kanji; Ishikawa, Kunio; Miyamoto, Youji

2016-01-01

Carbonate apatite (CO3Ap) foam has gained much attention in recent years because of its ability to rapidly replace bone. However, its mechanical strength is extremely low for clinical use. In this study, to understand the potential of gelatin-reinforced CO3Ap foam for bone replacement, CO3Ap foam was reinforced with gelatin and the resulting physical characteristics were evaluated. The mechanical strength increased significantly with the gelatin reinforcement. The compressive strength of gelatin-free CO3Ap foam was 74 kPa whereas that of the gelatin-reinforced CO3Ap foam, fabricated using 30 mass % gelatin solution, was approximately 3 MPa. Heat treatment for crosslinking gelatin had little effect on the mechanical strength of the foam. The gelatin-reinforced foam did not maintain its shape when immersed in a saline solution as this promoted swelling of the gelatin; however, in the same conditions, the heat-treated gelatin-reinforced foam proved to be stable. It is concluded, therefore, that heat treatment is the key to the fabrication of stable gelatin-reinforced CO3Ap foam. PMID:28773832

Optimizing Bone Health in Duchenne Muscular Dystrophy.

PubMed

Buckner, Jason L; Bowden, Sasigarn A; Mahan, John D

2015-01-01

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder characterized by progressive muscle weakness, with eventual loss of ambulation and premature death. The approved therapy with corticosteroids improves muscle strength, prolongs ambulation, and maintains pulmonary function. However, the osteoporotic impact of chronic corticosteroid use further impairs the underlying reduced bone mass seen in DMD, leading to increased fragility fractures of long bones and vertebrae. These serious sequelae adversely affect quality of life and can impact survival. The current clinical issues relating to bone health and bone health screening methods in DMD are presented in this review. Diagnostic studies, including biochemical markers of bone turnover and bone mineral density by dual energy X-ray absorptiometry (DXA), as well as spinal imaging using densitometric lateral spinal imaging, and treatment to optimize bone health in patients with DMD are discussed. Treatment with bisphosphonates offers a method to increase bone mass in these children; oral and intravenous bisphosphonates have been used successfully although treatment is typically reserved for children with fractures and/or bone pain with low bone mass by DXA.

Yeast-incorporated gallium attenuates glucocorticoid-induced bone loss in rats by inhibition of bone resorption.

PubMed

Ren, Zhaozhou; Yang, Liqing; Xue, Feng; Meng, Qingjie; Wang, Kejia; Wu, Xian; Ji, Chao; Jiang, Teng; Liu, Da; Zhou, Long; Zhang, Jing; Fu, Qin

2013-06-01

Glucocorticoids (GC) are potent anti-inflammatory agents and widely used for the treatment of many immune-mediated and inflammatory diseases, whereas GC-induced osteoporosis (GIOP) is the most common cause of secondary osteoporosis and significantly increases the patients' morbidity and mortality. GIOP is characterized as diminished osteogenesis and accelerated bone resorption. Yeast-incorporated gallium (YG) as an organic compound not only reduces elements-associated toxicity, but also maintains its therapeutic effect on improving bone loss or promoting fracture healing in ovariectomized female rats. The aim of this study was to examine whether YG could prevent GC-induced bone loss. Five-month-old male Sprague-Dawley rats were randomly divided into three groups (n = 6): two groups were administered dexamethasone (0.1 mg/kg/day) or vehicle (PBS) subcutaneously for 5 weeks; one other group was received dexamethasone subcutaneously and YG (120 μg/kg/day) orally. Trabecular bone microarchitectural parameters, bone mineral density (BMD), bone strength, body weight, and serum biochemical markers of bone resorption and formation were examined. Compared to the GC alone group, treatment with YG not only prevented microarchitectural deterioration of trabecular bone volume relative to tissue volume, trabecular number, and trabecular separation, but also significantly improved BMD, mechanical strength, and body weight in GC-treated rats. Moreover, YG decreased tartrate-resistant acid phosphatase 5b level but failed to change alkaline phosphatase level in GC-treated rats. This is the first study to show that YG prominently attenuates bone loss and microarchitectural deterioration and inhibits the increased bone resorption in GIOP. It implies that YG might be an alternative therapy for prevention of GC-induced bone loss in humans.

In vitro evaluation of three-dimensional single-walled carbon nanotube composites for bone tissue engineering.

PubMed

Gupta, Ashim; Main, Benjamin J; Taylor, Brittany L; Gupta, Manu; Whitworth, Craig A; Cady, Craig; Freeman, Joseph W; El-Amin, Saadiq F

2014-11-01

The purpose of this study was to develop three-dimensional single-walled carbon nanotube composites (SWCNT/PLAGA) using 10-mg single-walled carbon nanotubes (SWCNT) for bone regeneration and to determine the mechanical strength of the composites, and to evaluate the interaction of MC3T3-E1 cells via cell adhesion, growth, survival, proliferation, and gene expression. PLAGA (polylactic-co-glycolic acid) and SWCNT/PLAGA microspheres and composites were fabricated, characterized, and mechanical testing was performed. MC3T3-E1 cells were seeded and cell adhesion/morphology, growth/survival, proliferation, and gene expression analysis were performed to evaluate biocompatibility. Imaging studies demonstrated microspheres with uniform shape and smooth surfaces, and uniform incorporation of SWCNT into PLAGA matrix. The microspheres bonded in a random packing manner while maintaining spacing, thus resembling trabeculae of cancellous bone. Addition of SWCNT led to greater compressive modulus and ultimate compressive strength. Imaging studies revealed that MC3T3-E1 cells adhered, grew/survived, and exhibited normal, nonstressed morphology on the composites. SWCNT/PLAGA composites exhibited higher cell proliferation rate and gene expression compared with PLAGA. These results demonstrate the potential of SWCNT/PLAGA composites for musculoskeletal regeneration, for bone tissue engineering, and are promising for orthopedic applications as they possess the combined effect of increased mechanical strength, cell proliferation, and gene expression. © 2014 Wiley Periodicals, Inc.

Higher premenarcheal bone mass in elite gymnasts is maintained into young adulthood after long-term retirement from sport: a 14-year follow-up.

PubMed

Erlandson, Marta C; Kontulainen, Saija A; Chilibeck, Phil D; Arnold, Cathy M; Faulkner, Robert A; Baxter-Jones, Adam D G

2012-01-01

Sports that impact-load the skeleton during childhood and adolescence increase determinants of bone strength such as bone mineral content and density; however, it is unclear if this benefit is maintained after retirement from the sport. The purpose of this study was to assess whether the previously reported higher bone mass in a group of premenarcheal gymnasts was still apparent 10 years after the cessation of participation and withdrawal of the gymnastics loading stimulus. In 1995, 30 gymnasts 8 to 15 years of age were measured and compared with 30 age-matched nongymnasts. Twenty-five former gymnasts and 22 nongymnasts were measured again 14 years later (2009 to 2010). Gymnasts had been retired from gymnastics training and competition for an average of 10 years. Total body (TB), lumbar spine (LS), and femoral neck (FN) bone mineral content (BMC) was assessed at both measurement occasions by dual-energy X-ray absorptiometry (DXA). Multivariate analysis of covariance (MANCOVA) was used to compare former gymnasts' and nongymnasts' BMC while controlling for differences in body size and maturation (covariates: age, height, weight, and years from menarche [1995] or age at menarche [2009 to 2010]). Premenarcheal gymnasts (measured in 1995) had significantly greater size-adjusted TB, LS, and FN BMC (p < 0.05) (15%, 17%, and 12%, respectively) than nongymnasts. Ten years after retirement, gymnasts had maintained similar size-adjusted TB, LS, and FN BMC differences (p < 0.05) (13%, 19%, and 13%, respectively) when compared with nongymnasts. Bone mass benefits in premenarcheal gymnasts were still apparent even after long-term (10 years) removal of the gymnastics loading stimulus. Copyright © 2012 American Society for Bone and Mineral Research.

Engineering tubular bone using mesenchymal stem cell sheets and coral particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geng, Wenxin; Ma, Dongyang; Yan, Xingrong

Highlights: • We developed a novel engineering strategy to solve the limitations of bone grafts. • We fabricated tubular constructs using cell sheets and coral particles. • The composite constructs showed high radiological density and compressive strength. • These characteristics were similar to those of native bone. -- Abstract: The development of bone tissue engineering has provided new solutions for bone defects. However, the cell-scaffold-based approaches currently in use have several limitations, including low cell seeding rates and poor bone formation capacity. In the present study, we developed a novel strategy to engineer bone grafts using mesenchymal stem cell sheetsmore » and coral particles. Rabbit bone marrow mesenchymal stem cells were continuously cultured to form a cell sheet with osteogenic potential and coral particles were integrated into the sheet. The composite sheet was then wrapped around a cylindrical mandrel to fabricate a tubular construct. The resultant tubular construct was cultured in a spinner-flask bioreactor and subsequently implanted into a subcutaneous pocket in a nude mouse for assessment of its histological characteristics, radiological density and mechanical property. A similar construct assembled from a cell sheet alone acted as a control. In vitro observations demonstrated that the composite construct maintained its tubular shape, and exhibited higher radiological density, compressive strength and greater extracellular matrix deposition than did the control construct. In vivo experiments further revealed that new bone formed ectopically on the composite constructs, so that the 8-week explants of the composite sheets displayed radiological density similar to that of native bone. These results indicate that the strategy of using a combination of a cell sheet and coral particles has great potential for bone tissue engineering and repairing bone defects.« less

Dynamic acoustic radiation force retains bone structural and mechanical integrity in a functional disuse osteopenia model.

PubMed

Uddin, Sardar M Z; Qin, Yi-Xian

2015-06-01

Disuse osteopenia and bone loss have been extensively reported in long duration space mission and long term bed rest. The pathology of the bone loss is similar to osteoporosis but highly confined to weight bearing bones. The current anabolic and/or anti-resorptive drugs have systemic effects and are costly over extended time, with concerns of long term fracture risk. This study use Low Intensity Pulsed Ultrasound (LIPUS) as a non-invasive acoustic force and anabolic stimulus to countermeasure disuse induced bone loss. Four-month old C57BL/6 mice were randomized into five groups, 1) age-matched (AM), 2) non-suspended sham (NS), 3) non-suspended-LIPUS (NU), 4) suspended sham (SS), and 5) suspended-LIPUS (SU) groups. After four weeks of suspension, μCT analyses showed significant decreases in trabecular bone volume fraction (BV/TV) (-36%, p<0.005), bone tissue mineral density (TMD) (-3%, p<0.05), trabecular thickness (Tb.Th) (-12.5%, p<0.005), and increase in bone surface/bone volume (+BS/BV) (+16%, p<0.005), relative to age-matched (AM). The application of LIPUS for 20 min/day for 5 days/week, significantly increased TMD (+3%, p<0.05), Tb.Th (+6%, p<0.05), and decreased BS/BV (-10%, p<0.005), relative to suspension alone (SS) mice. Histomorphometry analyses showed a breakdown of bone microstructure under disuse conditions consist with μCT results. In comparison to SS mice, LIPUS treated bone showed increased structural integrity with increased bone formation rates at metaphysical endosteal and trabecular surfaces (+0.104±0.07 vs 0.031±0.30 μm(3)/μm(2)/day) relative to SS. Four-point bending mechanical tests of disused SS femurs showed reduced elastic modulus (-53%, p<0.05), yield (-33%, p<0.05) and ultimate strength (-45%, p<0.05) at the femoral diaphysis relative to AM bone. LIPUS stimulation mitigated the adverse effects of disuse on bone elastic modulus (+42%, p<0.05), yield strength (+29%, p<0.05), and ultimate strength (+39%, p<0.05) relative to SS femurs. LIPUS provides the essential mechanical stimulus to retain bone morphological and mechanical integrity in disuse conditions. This study demonstrates LIPUS potential as regional therapeutic agent to countermeasure disuse induced bone loss while maintaining bone's integrity. Copyright © 2015 Elsevier Inc. All rights reserved.

Effects of Ving Tsun Chinese martial art training on musculoskeletal health, balance performance, and self-efficacy in community-dwelling older adults.

PubMed

Lip, Ryan W T; Fong, Shirley S M; Ng, Shamay S M; Liu, Karen P Y; Guo, X

2015-03-01

[Purpose] The aim of this study was to investigate the effects of Ving Tsun (VT) Chinese martial art training on radial bone strength, upper- and lower-limb muscular strength, shoulder joint mobility, balance performance, and self-efficacy in elderly participants. [Subjects and Methods] Twelve seniors voluntarily joined the VT training group, and twenty-seven seniors voluntarily joined the control group. The VT group received VT training for three months, while the control group received no training. The bone strength of the distal radius was assessed using an ultrasound bone sonometer. Muscular strength in the limbs was evaluated using a Jamar handgrip dynamometer and the five times sit-to-stand test. Shoulder joint mobility was examined using a goniometer. Balance performance and self-efficacy were evaluated using the Berg Balance Scale and the Chinese version of the Activities-specific Balance Confidence Scale, respectively. [Results] The results revealed a nonsignificant group-by-time interaction effect, group effect, and time effect for all outcome variables. However, general trends of maintenance or improvement in all outcome parameters were observed to a greater extent in the VT group than in the control group. [Conclusion] VT training might be a potential fall-prevention exercise that can be used to maintain general physique, balance, and confidence in the elderly population. A further randomized controlled trial is needed to confirm this postulation.

Effects of Ving Tsun Chinese martial art training on musculoskeletal health, balance performance, and self-efficacy in community-dwelling older adults

PubMed Central

Lip, Ryan W.T.; Fong, Shirley S.M.; Ng, Shamay S.M.; Liu, Karen P.Y.; Guo, X.

2015-01-01

[Purpose] The aim of this study was to investigate the effects of Ving Tsun (VT) Chinese martial art training on radial bone strength, upper- and lower-limb muscular strength, shoulder joint mobility, balance performance, and self-efficacy in elderly participants. [Subjects and Methods] Twelve seniors voluntarily joined the VT training group, and twenty-seven seniors voluntarily joined the control group. The VT group received VT training for three months, while the control group received no training. The bone strength of the distal radius was assessed using an ultrasound bone sonometer. Muscular strength in the limbs was evaluated using a Jamar handgrip dynamometer and the five times sit-to-stand test. Shoulder joint mobility was examined using a goniometer. Balance performance and self-efficacy were evaluated using the Berg Balance Scale and the Chinese version of the Activities-specific Balance Confidence Scale, respectively. [Results] The results revealed a nonsignificant group-by-time interaction effect, group effect, and time effect for all outcome variables. However, general trends of maintenance or improvement in all outcome parameters were observed to a greater extent in the VT group than in the control group. [Conclusion] VT training might be a potential fall-prevention exercise that can be used to maintain general physique, balance, and confidence in the elderly population. A further randomized controlled trial is needed to confirm this postulation. PMID:25931704

Influence of high-fat diet from differential dietary sources on bone mineral density, bone strength, and bone fatty acid composition in rats.

PubMed

Lau, Beatrice Y; Fajardo, Val Andrew; McMeekin, Lauren; Sacco, Sandra M; Ward, Wendy E; Roy, Brian D; Peters, Sandra J; Leblanc, Paul J

2010-10-01

Previous studies have suggested that high-fat diets adversely affect bone development. However, these studies included other dietary manipulations, including low calcium, folic acid, and fibre, and (or) high sucrose or cholesterol, and did not directly compare several common sources of dietary fat. Thus, the overall objective of this study was to investigate the effect of high-fat diets that differ in fat quality, representing diets high in saturated fatty acids (SFA), n-3 polyunsaturated fatty acids (PUFA), or n-6 PUFA, on femur bone mineral density (BMD), strength, and fatty acid composition. Forty-day-old male Sprague-Dawley rats were maintained for 65 days on high-fat diets (20% by weight), containing coconut oil (SFA; n = 10), flaxseed oil (n-3 PUFA; n = 10), or safflower oil (n-6 PUFA; n = 11). Chow-fed rats (n = 10), at 105 days of age, were included to represent animals on a control diet. Rats fed high-fat diets had higher body weights than the chow-fed rats (p < 0.001). Among all high-fat groups, there were no differences in femur BMD (p > 0.05) or biomechanical strength properties (p > 0.05). Femurs of groups fed either the high n-3 or high n-6 PUFA diets were stronger (as measured by peak load) than those of the chow-fed group, after adjustment for significant differences in body weight (p = 0.001). As expected, the femur fatty acid profile reflected the fatty acid composition of the diet consumed. These results suggest that high-fat diets, containing high levels of PUFA in the form of flaxseed or safflower oil, have a positive effect on bone strength when fed to male rats 6 to 15 weeks of age.

High doses of vitamin C plus E reduce strength training-induced improvements in areal bone mineral density in elderly men.

PubMed

Stunes, Astrid Kamilla; Syversen, Unni; Berntsen, Sveinung; Paulsen, Gøran; Stea, Tonje H; Hetlelid, Ken J; Lohne-Seiler, Hilde; Mosti, Mats Peder; Bjørnsen, Thomas; Raastad, Truls; Haugeberg, Glenn

2017-06-01

Resistance training is beneficial for maintaining bone mass. We aimed to investigate the skeletal effects of high doses of antioxidants [vitamin C + E (α-tocopherol)] supplementation during 12-week supervised strength training in healthy, elderly men METHODS: Design: double-blinded randomized placebo-controlled study. Participants followed a supervised, undulating periodic exercise program with weekly adjusted load: 3 sessions/week and 3-15 repetitions maximum (RM) sets/exercise. The control group (CG, n = 17, 67 ± 5 years) received placebo and the antioxidant group (AO, n = 16, 70 ± 7 years) 1000 mg vitamin C + 235 mg vitamin E, daily. Areal bone mineral density (aBMD) at whole body, lumbar spine (L1-L4), total hip, and femoral neck were measured by dual energy X-ray absorptiometry and muscle strength by 1RM. Serum analyses of bone-related factors and adipokines were performed. In the CG, total hip aBMD increased by 1.0% (CI: 0.3-1.7) versus pretest and lumbar spine aBMD increased by 0.9% (CI: -0.2 to 2.0) compared to the AO. In the CG, there was an increase in serum concentrations of insulin-like growth factor 1 [+27.3% (CI: -0.3 to 54.9)] and leptin [+31.2% (CI: 9.8-52.6)) versus pretest, and a decrease in sclerostin [-9.9% (CI: 4.4-15.3)] versus pretest and versus AO. Serum bone formation markers P1NP and osteocalcin increased in both groups, while the bone resorption marker CTX-1 remained unchanged. High doses of antioxidant supplementations may constrain the favorable skeletal benefits of 12 weeks of resistance exercise in healthy elderly men.

Modification of bone graft by blending with lecithin to improve hydrophilicity and biocompatibility.

PubMed

Wang, Y; Cui, F Z; Jiao, Y P; Hu, K; Fan, D D

2008-03-01

Lecithin was blended to improve the hydrophilicity and biocompatibility of bone graft containing poly(l-lactic acid) (PLLA). Solution blending and freeze drying were used to fabricate symmetrical scaffolds containing different percentages of lecithin (lecithin: PLLA = 0, 5, 10 wt%). Scanning electron microscopy showed that the scaffolds maintained the three-dimensional porous structure. A water uptake experiment proved the significant improvement of hydrophilicity of the blend scaffold. With the addition of lecithin, the compressive strength and compressive modulus decreased. When the weight ratio of lecithin to PLLA was up to 10%, the compressive strength was still more than the lower limit of natural cancellous bone. To test the biocompatibility of the scaffolds, cell culture in vitro and subcutaneous implantation in vivo were performed. MC3T3-E1 preosteoblastic cells were cultured on the scaffolds for 7 days. Methylthiazol tetrazolium assay and laser scanning confocal microscopy were used to exhibit proliferation and morphology of the cells. The subcutaneous implantation in rats tested inflammatory response to the scaffolds. The results proved the better biocompatibility and milder inflammatory reactions of the blend scaffold (lecithin: PLLA = 5%) compared with the scaffold without lecithin. The modified scaffold containing lecithin is promising for bone tissue engineering.

Obstacles in the optimization of bone health outcomes in the female athlete triad.

PubMed

Ducher, Gaele; Turner, Anne I; Kukuljan, Sonja; Pantano, Kathleen J; Carlson, Jennifer L; Williams, Nancy I; De Souza, Mary Jane

2011-07-01

Maintaining low body weight for the sake of performance and aesthetic purposes is a common feature among young girls and women who exercise on a regular basis, including elite, college and high-school athletes, members of fitness centres, and recreational exercisers. High energy expenditure without adequate compensation in energy intake leads to an energy deficiency, which may ultimately affect reproductive function and bone health. The combination of low energy availability, menstrual disturbances and low bone mineral density is referred to as the 'female athlete triad'. Not all athletes seek medical assistance in response to the absence of menstruation for 3 or more months as some believe that long-term amenorrhoea is not harmful. Indeed, many women may not seek medical attention until they sustain a stress fracture. This review investigates current issues, controversies and strategies in the clinical management of bone health concerns related to the female athlete triad. Current recommendations focus on either increasing energy intake or decreasing energy expenditure, as this approach remains the most efficient strategy to prevent further bone health complications. However, convincing the athlete to increase energy availability can be extremely challenging. Oral contraceptive therapy seems to be a common strategy chosen by many physicians to address bone health issues in young women with amenorrhoea, although there is little evidence that this strategy improves bone mineral density in this population. Assessment of bone health itself is difficult due to the limitations of dual-energy X-ray absorptiometry (DXA) to estimate bone strength. Understanding how bone strength is affected by low energy availability, weight gain and resumption of menses requires further investigations using 3-dimensional bone imaging techniques in order to improve the clinical management of the female athlete triad.

Local deformation behavior of surface porous polyether-ether-ketone.

PubMed

Evans, Nathan T; Torstrick, F Brennan; Safranski, David L; Guldberg, Robert E; Gall, Ken

2017-01-01

Surface porous polyether-ether-ketone has the ability to maintain the tensile monotonic and cyclic strength necessary for many load bearing orthopedic applications while providing a surface that facilitates bone ingrowth; however, the relevant deformation behavior of the pore architecture in response to various loading conditions is not yet fully characterized or understood. The focus of this study was to examine the compressive and wear behavior of the surface porous architecture using micro Computed Tomography (micro CT). Pore architectures of various depths (~0.5-2.5mm) and pore sizes (212-508µm) were manufactured using a melt extrusion and porogen leaching process. Compression testing revealed that the pore architecture deforms in the typical three staged linear elastic, plastic, and densification stages characteristic of porous materials. The experimental moduli and yield strengths decreased as the porosity increased but there was no difference in properties between pore sizes. The porous architecture maintained a high degree of porosity available for bone-ingrowth at all strains. Surface porous samples showed no increase in wear rate compared to injection molded samples, with slight pore densification accompanying wear. Copyright © 2016 Elsevier Ltd. All rights reserved.

Segmental Bone Regeneration Using a Load Bearing Biodegradable Carrier of Bone Morphogenetic Protein-2

PubMed Central

Chu, Tien-Min G.; Warden, Stuart J.; Turner, Charles H.; Stewart, Rena L.

2006-01-01

Segmental defect regeneration has been a clinical challenge. Current tissue engineering approach using porous biodegradable scaffolds to delivery osteogenic cells and growth factors demonstrated success in facilitating bone regeneration in these cases. However, due to the lack of mechanical property, the porous scaffolds were evaluated in non-load bearing area or were stabilized with stress-shielding devices (bone plate or external fixation). In this paper, we tested a scaffold that does not require a bone plate because it has sufficient biomechanical strength. The tube-shaped scaffolds were manufactured from poly(propylene) fumarate/tricalcium phosphate (PPF/TCP) composites. Dicalcium phosphate dehydrate (DCPD) were used as bone morphogenetic protein -2 (BMP-2) carrier. Twenty two scaffolds were implanted in 5 mm segmental defects in rat femurs stabilized with k-wire for 6 and 15 weeks with and without 10 μg of rhBMP-2. Bridging of the segmental defect was evaluated first radiographically and was confirmed by histology and micro- computer tomography (μ-CT) imaging. The scaffolds in the BMP group maintained the bone length throughout the duration of the study and allow for bridging. The scaffolds in the control group failed to induce bridging and collapsed at 15 weeks. Peripheral computed tomography (pQCT) showed that BMP-2 does not increase the bone mineral density in the callus. Finally, the scaffold in BMP group was found to restore the mechanical property of the rat femur after 15 weeks. Our results demonstrated that the load-bearing BMP-2 scaffold can maintain bone length and allow successfully regeneration in segmental defects. PMID:16996588

[Development, physiology, and cell activity of bone].

PubMed

de Baat, P; Heijboer, M P; de Baat, C

2005-07-01

Bones are of crucial importance for the human body, providing skeletal support, serving as a home for the formation of haematopoietic cells, and reservoiring calcium and phosphate. Long bones develop by endochondral ossification. Flat bones develop by intramembranous ossification. Bone tissue contains hydroxyapatite and various extracellular proteins, producing bone matrix. Two biological mechanisms, determining the strength of bone, are modelling and remodelling. Modelling can change bone shape and size through bone formation by osteoblasts at some sites and through bone destruction by osteoclasts at other sites. Remodelling is bone turnover, also performed by osteoclasts and osteoblasts. The processes of modelling and remodelling are induced by mechanical loads, predominantly muscle loads. Osteoblasts develop from mesenchymal stem cells. Many stimulating factors are known to activate the differentiation. Mature osteoblasts synthesize bone matrix and may further differentiate into osteocytes. Osteocytes maintain structural bone integrity and allow bone to adapt to any mechanical and chemical stimulus. Osteoclasts derive from haematopoietic stem cells. A number of transcription and growth factors have been identified essential for osteoclast differentiation and function. Finally, there is a complex interaction between osteoblasts and osteoclasts. Bone destruction starts by attachment of osteoclasts to the bone surface. Following this, osteoclasts undergo specific morphological changes. The process of bone destruction starts by acid dissolution of hydroxyapatite. After that osteoclasts start to destruct the organic matrix.

The Loss of Activating Transcription Factor 4 (ATF4) Reduces Bone Toughness and Fracture Toughness

PubMed Central

Makowski, Alexander J.; Uppuganti, Sasidhar; Waader, Sandra A.; Whitehead, Jack M.; Rowland, Barbara J.; Granke, Mathilde; Mahadevan-Jansen, Anita; Yang, Xiangli; Nyman, Jeffry S.

2014-01-01

Even though age-related changes to bone tissue affecting fracture risk are well characterized, only a few matrix-related factors have been identified as important to maintaining fracture resistance. As a gene critical to osteoblast differentiation, activating transcription factor 4 (ATF4) is possibly one of the seimportant factors. To test the hypothesis that the loss of ATF4 affects the fracture resistance of bone beyond bone mass and structure, we harvested bones from Atf4+/+ and Atf4−/− littermates at 8 and 20 weeks of age (n≥9 per group) for bone assessment across several length scales. From whole bone mechanical tests in bending, femurs from Atf4−/− mice were found to be brittle with reduced toughness and fracture toughness compared to femurs from Atf4+/+ mice. However, there were no differences in material strength and in tissue hardness, as determined by nanoindentation, between the genotypes, irrespective age. Tissue mineral density of the cortex at the point of loading as determined by micro-computed tomography was also not significantly different. However, by analyzing local composition by Raman Spectroscopy (RS), bone tissue of Atf4−/− mice was found to have higher mineral to collagen ratio compared to wild-type tissue, primarily at 20 weeks of age. From RS analysis of intact femurs at 2 orthogonal orientations relative to the polarization axis of the laser, we also found that the organizational-sensitive peak ratio, ν1 Phosphate per Amide I, changed to a greater extent upon bone rotation for Atf4-deficient tissue, implying bone matrix organization may contribute to the brittleness phenotype. Target genes of ATF4 activity are not only important to osteoblast differentiation but also maintaining bone toughness and fracture toughness. PMID:24509412

The loss of activating transcription factor 4 (ATF4) reduces bone toughness and fracture toughness.

PubMed

Makowski, Alexander J; Uppuganti, Sasidhar; Wadeer, Sandra A; Whitehead, Jack M; Rowland, Barbara J; Granke, Mathilde; Mahadevan-Jansen, Anita; Yang, Xiangli; Nyman, Jeffry S

2014-05-01

Even though age-related changes to bone tissue affecting fracture risk are well characterized, only a few matrix-related factors have been identified as important to maintaining fracture resistance. As a gene critical to osteoblast differentiation, activating transcription factor 4 (ATF4) is possibly one of these important factors. To test the hypothesis that the loss of ATF4 affects the fracture resistance of bone beyond bone mass and structure, we harvested bones from Atf4+/+ and Atf4-/- littermates at 8 and 20 weeks of age (n≥9 per group) for bone assessment across several length scales. From whole bone mechanical tests in bending, femurs from Atf4-/- mice were found to be brittle with reduced toughness and fracture toughness compared to femurs from Atf4+/+ mice. However, there were no differences in material strength and in tissue hardness, as determined by nanoindentation, between the genotypes, irrespective of age. Tissue mineral density of the cortex at the point of loading as determined by micro-computed tomography was also not significantly different. However, by analyzing local composition by Raman Spectroscopy (RS), bone tissue of Atf4-/- mice was found to have higher mineral to collagen ratio compared to wild-type tissue, primarily at 20 weeks of age. From RS analysis of intact femurs at 2 orthogonal orientations relative to the polarization axis of the laser, we also found that the organizational-sensitive peak ratio, ν1Phosphate per Amide I, changed to a greater extent upon bone rotation for Atf4-deficient tissue, implying bone matrix organization may contribute to the brittleness phenotype. Target genes of ATF4 activity are not only important to osteoblast differentiation but also in maintaining bone toughness and fracture toughness. Published by Elsevier Inc.

The role of dietary protein and vitamin D in maintaining musculoskeletal health in postmenopausal women: a consensus statement from the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO).

PubMed

Rizzoli, René; Stevenson, John C; Bauer, Jürgen M; van Loon, Luc J C; Walrand, Stéphane; Kanis, John A; Cooper, Cyrus; Brandi, Maria-Luisa; Diez-Perez, Adolfo; Reginster, Jean-Yves

2014-09-01

From 50 years of age, postmenopausal women are at an increased risk of developing sarcopenia and osteoporosis as a result of deterioration of musculoskeletal health. Both disorders increase the risk of falls and fractures. The risk of developing sarcopenia and osteoporosis may be attenuated through healthy lifestyle changes, which include adequate dietary protein, calcium and vitamin D intakes, and regular physical activity/exercise, besides hormone replacement therapy when appropriate. Protein intake and physical activity are the main anabolic stimuli for muscle protein synthesis. Exercise training leads to increased muscle mass and strength, and the combination of optimal protein intake and exercise produces a greater degree of muscle protein accretion than either intervention alone. Similarly, adequate dietary protein intake and resistance exercise are important contributors to the maintenance of bone strength. Vitamin D helps to maintain muscle mass and strength as well as bone health. These findings suggest that healthy lifestyle measures in women aged >50 years are essential to allow healthy ageing. The European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO) recommends optimal dietary protein intake of 1.0-1.2g/kgbodyweight/d with at least 20-25g of high-quality protein at each main meal, with adequate vitamin D intake at 800IU/d to maintain serum 25-hydroxyvitamin D levels >50nmol/L as well as calcium intake of 1000mg/d, alongside regular physical activity/exercise 3-5 times/week combined with protein intake in close proximity to exercise, in postmenopausal women for prevention of age-related deterioration of musculoskeletal health. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Muscle strength and areal bone mineral density at the hip in women: a cross-sectional study.

PubMed

Pasco, Julie A; Holloway, Kara L; Brennan-Olsen, Sharon L; Moloney, David J; Kotowicz, Mark A

2015-05-24

Muscle strengthening exercises are promoted for building and maintaining a healthy skeleton. We aimed to investigate the relationship between muscle strength and areal bone mineral density (BMD) at the hip in women aged 26-97 years. This cross-sectional study utilises data from 863 women assessed for the Geelong Osteoporosis Study. Measures of hip flexor and abductor strength were made using a hand-held dynamometer (Nicholas Manual Muscle Tester). The maximal measure from three trials on each leg was used for analyses. BMD was measured at the hip using dual energy x-ray absorptiometry (DXA; Lunar DPX-L). Total lean mass, body fat mass and appendicular lean mass were determined from whole body DXA scans. Linear regression techniques were used with muscle strength as the independent variable and BMD as the dependent variable. Models were adjusted for age and indices of body composition. Measures of age-adjusted hip flexor strength and hip abductor strength were positively associated with total hip BMD. For each standard deviation (SD) increase in hip flexor strength, the increase in mean total hip BMD (SD) was 10.4 % (p = 0.009). A similar pattern was observed for hip abductor strength, with an increase in mean total hip BMD of 22.8 % (p = 0.025). All associations between hip muscle strength and total hip BMD were independent of height, but were nullified after adjusting for appendicular lean mass or total lean mass. There was a positive association observed between muscle strength and BMD at the hip. However, this association was explained by measures of lean mass.

A Mineral-Rich Extract from the Red Marine Algae Lithothamnion calcareum Preserves Bone Structure and Function in Female Mice on a Western-Style Diet

PubMed Central

Aslam, Muhammad Nadeem; Kreider, Jaclynn M.; Paruchuri, Tejaswi; Bhagavathula, Narasimharao; DaSilva, Marissa; Zernicke, Ronald F.; Goldstein, Steven A.; Varani, James

2010-01-01

The purpose of this study was to determine whether a mineral-rich extract derived from the red marine algae Lithothamnion calcareum could be used as a dietary supplement for prevention of bone mineral loss. Sixty C57BL/6 mice were divided into three groups based on diet: the first group received a high-fat Western-style diet (HFWD), the second group was fed the same HFWD along with the mineral-rich extract included as a dietary supplement, and the third group was used as a control and was fed a low-fat rodent chow diet (AIN76A). Mice were maintained on the respective diets for 15 months. Then, long bones (femora and tibiae) from both males and females were analyzed by three-dimensional micro-computed tomography (micro-CT) and (bones from female mice) concomitantly assessed in bone strength studies. Tartrate-resistant acid phosphatase (TRAP), osteocalcin, and N-terminal peptide of type I procollagen (PINP) were assessed in plasma samples obtained from female mice at the time of sacrifice. To summarize, female mice on the HFWD had reduced bone mineralization and reduced bone strength relative to female mice on the low-fat chow diet. The bone defects in female mice on the HFWD were overcome in the presence of the mineral-rich supplement. In fact, female mice receiving the mineral-rich supplement in the HFWD had better bone structure/function than did female mice on the low-fat chow diet. Female mice on the mineral-supplemented HFWD had higher plasma levels of TRAP than mice of the other groups. There were no differences in the other two markers. Male mice showed little diet-specific differences by micro-CT. PMID:20180099

Current perspectives on the etiology and manifestation of the “silent” component of the Female Athlete Triad

PubMed Central

Mallinson, Rebecca J; De Souza, Mary Jane

2014-01-01

The Female Athlete Triad (Triad) represents a syndrome of three interrelated conditions that originate from chronically inadequate energy intake to compensate for energy expenditure; this environment results in insufficient stored energy to maintain physiological processes, a condition known as low energy availability. The physiological adaptations associated with low energy availability, in turn, contribute to menstrual cycle disturbances. The downstream effects of both low energy availability and suppressed estrogen concentrations synergistically impair bone health, leading to low bone mineral density, compromised bone structure and microarchitecture, and ultimately, a decrease in bone strength. Unlike the other components of the Triad, poor bone health often does not have overt symptoms, and therefore develops silently, unbeknownst to the athlete. Compromised bone health among female athletes increases the risk of fracture throughout the lifespan, highlighting the long-term health consequences of the Triad. The purpose of this review is to examine the current state of Triad research related to the third component of the Triad, ie, poor bone health, in an effort to summarize what we know, what we are learning, and what remains unknown. PMID:24833922

Relative contributions of lean and fat mass to bone strength in young Hispanic and non-Hispanic girls.

PubMed

Hetherington-Rauth, Megan; Bea, Jennifer W; Blew, Robert M; Funk, Janet L; Hingle, Melanie D; Lee, Vinson R; Roe, Denise J; Wheeler, Mark D; Lohman, Timothy G; Going, Scott B

2018-05-22

With the high prevalence of childhood obesity, especially among Hispanic children, understanding how body weight and its components of lean and fat mass affect bone development is important, given that the amount of bone mineral accrued during childhood can determine osteoporosis risk later in life. The aim of this study was to assess the independent contributions of lean and fat mass on volumetric bone mineral density (vBMD), geometry, and strength in both weight-bearing and non-weight-bearing bones of Hispanic and non-Hispanic girls. Bone vBMD, geometry, and strength were assessed at the 20% distal femur, the 4% and 66% distal tibia, and the 66% distal radius of the non-dominant limb of 326, 9- to 12-year-old girls using peripheral quantitative computed tomography (pQCT). Total body lean and fat mass were measured by dual-energy x-ray absorptiometry (DXA). Multiple linear regression was used to assess the independent relationships of fat and lean mass with pQCT bone measures while adjusting for relevant confounders. Potential interactions between ethnicity and both fat and lean mass were also tested. Lean mass was a significant positive contributor to all bone outcomes (p < 0.05) with the exception of vBMD at diaphyseal sites. Fat mass was a significant contributor to bone strength at weight bearing sites, but did not significantly contribute to bone strength at the non-weight bearing radius and was negatively associated with radius cortical content and thickness. Bone measures did not significantly differ between Hispanic and non-Hispanic girls, although there was a significant interaction between ethnicity and fat mass with total bone area at the femur (p = 0.02) and 66% tibia (p = 0.005) as well as bone strength at the femur (p = 0.03). Lean mass is the main determinant of bone strength for appendicular skeletal sites. Fat mass contributes to bone strength in the weight-bearing skeleton but does not add to bone strength in non-weight-bearing locations and may potentially be detrimental. Bone vBMD, geometry, and strength did not differ between Hispanic and non-Hispanic girls; fat mass may be a stronger contributor to bone strength in weight-bearing bones of Hispanic girls compared to non-Hispanic. Copyright © 2018. Published by Elsevier Inc.

Pathogenesis of osteoporotic hip fractures.

PubMed

McClung, Michael R

2003-01-01

Osteoporosis is characterized late in the course of the disease by an increased risk of fracture, particularly in the elderly. It occurs in both sexes, affecting approximately 8 million women and 2 million men aged > or = 50 years (1). While low bone density is a predictor of fractures, it is not the only determinant of fracture risk. Other factors include advanced age, altered bone quality, a personal or family history of falls, frailty, poor eyesight, debilitating diseases, and high bone turnover. A diet with sufficient calcium and vitamin D is important to minimize bone loss and, along with regular exercise, to maintain muscle strength. Bisphosphonates have been shown to reduce the risk of hip fracture. For elderly patients, the use of hip protectors may be used as a treatment of last resort. Regardless of the age of the patient, individual patient risk factors must be considered to target appropriate treatment and prevent fracture.

Bone Metabolism on ISS Missions

NASA Technical Reports Server (NTRS)

Smith, S. M.; Heer, M. A.; Shackelford, L. C.; Zwart, S. R.

2014-01-01

Spaceflight-induced bone loss is associated with increased bone resorption (1, 2), and either unchanged or decreased rates of bone formation. Resistive exercise had been proposed as a countermeasure, and data from bed rest supported this concept (3). An interim resistive exercise device (iRED) was flown for early ISS crews. Unfortunately, the iRED provided no greater bone protection than on missions where only aerobic and muscular endurance exercises were available (4, 5). In 2008, the Advanced Resistive Exercise Device (ARED), a more robust device with much greater resistance capability, (6, 7) was launched to the ISS. Astronauts who had access to ARED, coupled with adequate energy intake and vitamin D status, returned from ISS missions with bone mineral densities virtually unchanged from preflight (7). Bone biochemical markers showed that while the resistive exercise and adequate energy consumption did not mitigate the increased bone resorption, bone formation was increased (7, 8). The typical drop in circulating parathyroid hormone did not occur in ARED crewmembers. In 2014, an updated look at the densitometry data was published. This study confirmed the initial findings with a much larger set of data. In 42 astronauts (33 male, 9 female), the bone mineral density response to flight was the same for men and women (9), and those with access to the ARED did not have the typical decrease in bone mineral density that was observed in early ISS crewmembers with access to the iRED (Figure 1) (7). Biochemical markers of bone formation and resorption responded similarly in men and women. These data are encouraging, and represent the first in-flight evidence in the history of human space flight that diet and exercise can maintain bone mineral density on long-duration missions. However, the maintenance of bone mineral density through bone remodeling, that is, increases in both resorption and formation, may yield a bone with strength characteristics different from those that existed before space flight. Studies to assess bone strength after flight are underway at NASA, to better understand the results of bone remodeling. Studies are also underway to evaluate optimized exercise protocols and nutritional countermeasures. Regardless, there is clear evidence of progress being made to protect bone during spaceflight.

Bone strength estimates relative to vertical ground reaction force discriminates women runners with stress fracture history.

PubMed

Popp, Kristin L; McDermott, William; Hughes, Julie M; Baxter, Stephanie A; Stovitz, Steven D; Petit, Moira A

2017-01-01

To determine differences in bone geometry, estimates of bone strength, muscle size and bone strength relative to load, in women runners with and without a history of stress fracture. We recruited 32 competitive distance runners aged 18-35, with (SFX, n=16) or without (NSFX, n=16) a history of stress fracture for this case-control study. Peripheral quantitative computed tomography (pQCT) was used to assess volumetric bone mineral density (vBMD, mg/mm 3 ), total (ToA) and cortical (CtA) bone areas (mm 2 ), and estimated compressive bone strength (bone strength index; BSI, mg/mm 4 ) at the distal tibia. ToA, CtA, cortical vBMD, and estimated strength (section modulus; Zp, mm 3 and strength strain index; SSIp, mm 3 ) were measured at six cortical sites along the tibia. Mean active peak vertical (pkZ) ground reaction forces (GRFs), assessed from a fatigue run on an instrumented treadmill, were used in conjunction with pQCT measurements to estimate bone strength relative to load (mm 2 /N∗kg -1 ) at all cortical sites. SSIp and Zp were 9-11% lower in the SFX group at mid-shaft of the tibia, while ToA and vBMD did not differ between groups at any measurement site. The SFX group had 11-17% lower bone strength relative to mean pkZ GRFs (p<0.05). These findings indicate that estimated bone strength at the mid-tibia and mean pkZ GRFs are lower in runners with a history of stress fracture. Bone strength relative to load is also lower in this same region suggesting that strength deficits in the middle 1/3 of the tibia and altered gait biomechanics may predispose an individual to stress fracture. Copyright © 2016. Published by Elsevier Inc.

Force-induced bone growth and adaptation: A system theoretical approach to understanding bone mechanotransduction

NASA Astrophysics Data System (ADS)

Maldonado, Solvey; Findeisen, Rolf

2010-06-01

The modeling, analysis, and design of treatment therapies for bone disorders based on the paradigm of force-induced bone growth and adaptation is a challenging task. Mathematical models provide, in comparison to clinical, medical and biological approaches an structured alternative framework to understand the concurrent effects of the multiple factors involved in bone remodeling. By now, there are few mathematical models describing the appearing complex interactions. However, the resulting models are complex and difficult to analyze, due to the strong nonlinearities appearing in the equations, the wide range of variability of the states, and the uncertainties in parameters. In this work, we focus on analyzing the effects of changes in model structure and parameters/inputs variations on the overall steady state behavior using systems theoretical methods. Based on an briefly reviewed existing model that describes force-induced bone adaptation, the main objective of this work is to analyze the stationary behavior and to identify plausible treatment targets for remodeling related bone disorders. Identifying plausible targets can help in the development of optimal treatments combining both physical activity and drug-medication. Such treatments help to improve/maintain/restore bone strength, which deteriorates under bone disorder conditions, such as estrogen deficiency.

Prevalence of Poor Bone Quality in Women Undergoing Spinal Fusion Using Biomechanical-CT Analysis.

PubMed

Burch, Shane; Feldstein, Michael; Hoffmann, Paul F; Keaveny, Tony M

2016-02-01

Retrospective, cross-sectional analysis of vertebral bone quality in spine-fusion patients at a single medical center. To characterize the prevalence of osteoporosis and fragile bone strength in a spine-fusion population of women with an age range of 50 years to 70 years. Fragile bone strength is defined as the level of vertebral strength below which a patient is at as high a risk of future vertebral fracture as a patient having bone density-defined osteoporosis. Poor bone quality--defined here as the presence of either osteoporosis or fragile bone strength--is a risk factor for spine-fusion patients that often goes undetected but can now be assessed preoperatively by additional postprocessing of computed tomography (CT) scans originally ordered for perioperative clinical assessment. Utilizing such perioperative CT scans for a cohort of 98 women (age range: 51-70 yr) about to undergo spine fusion, we retrospectively used a phantomless calibration technique and biomechanical-CT postprocessing analysis to measure vertebral trabecular bone mineral density (BMD) (in mg/cm³) and by nonlinear finite element analysis, vertebral compressive strength (in Newtons, N) in the L1 or L2 vertebra. Preestablished validated threshold values were used to define the presence of osteoporosis (trabecular BMD of 80 mg/cm³ or lower) and fragile bone strength (vertebral strength of 4500 N or lower). Fourteen percent of the women tested positive for osteoporosis, 27% tested positive for fragile bone strength, and 29% were classified as having poor bone quality (either osteoporosis or fragile bone strength). Over this narrow age range, neither BMD nor vertebral strength were significantly correlated with age, weight, height, or body mass index (P values 0.14-0.97 for BMD; 0.13-0.51 for strength). Poor bone quality appears to be common in women between ages 50 years and 70 years undergoing spinal fusion surgery. 3.

Influence of lactose addition to gentamicin-loaded acrylic bone cement on the kinetics of release of the antibiotic and the cement properties.

PubMed

Frutos, Gloria; Pastor, José Ygnacio; Martínez, Noelia; Virto, María Rosa; Torrado, Susana

2010-03-01

The purpose of this study was to characterize a poly(methyl methacrylate) bone cement that was loaded with the antibiotic gentamicin sulphate (GS) and lactose, which served to modulate the release of GS from cement specimens. The release of GS when the cement specimens were immersed in phosphate-buffered saline at 37 degrees Celsius was determined spectrophotometrically. The microstructure, porosity, density, tensile properties and flexural properties of the cements were determined before and after release of GS. A kinetics model of the release of GS from the cement that involved a coupled mechanism based on dissolution/diffusion processes and an initial burst effect was proposed. Dissolution assay results showed that drug elution was controlled by a diffusion mechanism which can be modulated by lactose addition. Density values and mechanical properties (tensile strength, flexural strength, elastic modulus and fracture toughness) were reduced by the increased porosity resulting from lactose addition, but maintained acceptable values for the structural functions of bone cement. The present results suggest that lactose-modified, gentamicin-loaded acrylic bone cements are potential candidates for use in various orthopaedic and dental applications. Copyright 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The Effects of Partial Mechanical Loading and Ibandronate on Skeletal Tissues in the Adult Rat Hindquarter Suspension Model for Microgravity

NASA Technical Reports Server (NTRS)

Schultheis, Lester W.

1999-01-01

We report initial data from a suspended rat model that quantitatively relates chronic partial weightbearing to bone loss. Chronic partial weightbearing is our simulation of the effect of limited artificial gravity aboard spacecraft or reduced planetary gravity. Preliminary analysis of bone by PQCT, histomorphometry, mechanical testing and biochemistry suggest that chronic exposure to half of Earth gravity is insufficient to prevent severe bone loss. The effect of episodic full weightbearing activity (Earth Gravity) on rats otherwise at 50% weightbearing was also explored. This has similarity to treatment by an Earth G-rated centrifuge on a spacecraft that normally maintained artificial gravity at half of Earth G. Our preliminary evidence, using the above techniques to analyze bone, indicate that 2 hours daily of full weightbearing was insufficient to prevent the bone loss observed in 50% weightbearing animals. The effectiveness of partial weightbearing and episodic full weightbearing as potential countermeasures to bone loss in spaceflight was compared with treatment by ibandronate. Ibandronate, a long-acting potent bisphosphonate proved more effective in preventing bone loss and associated functionality based upon structure than our first efforts at mechanical countermeasures. The effectiveness of ibandronate was notable by each of the testing methods we used to study bone from gross structure and strength to tissue and biochemistry. These results appear to be independent of generalized systemic stress imposed by the suspension paradigm. Preliminary evidence does not suggest that blood levels of vitamin D were affected by our countermeasures. Despite the modest theraputic benefit of mechanical countermeasures of partial weightbearing and episodic full weightbearing, we know that some appropriate mechanical signal maintains bone mass in Earth gravity. Moreover, the only mechanism that correctly assigns bone mass and strength to oppose regionally specific force applied to bone is mechanical, a process based upon bone strain. Substantial evidence indicates that the specifics of dynamic loading i.e. time-varying forces are critical. Bone strain history is a predictor of the effect that mechanical conditions have on bone structure mass and strength. Using servo-controlled force plates on suspended rats with implanted strain gauges we manipulated impact forces of ambulation in the frequency (Fourier) domain. Our results indicate that high frequency components of impact forces are particularly potent in producing bone strain independent of the magnitude of the peak force or peak energy applied to the leg. Because a servo-system responds to forces produced by the rat's own muscle activity during ambulation, the direction of ground-reaction loads act on bone through the rat's own musculature. This is in distinction to passive vibration of the floor where forces reach bone through the natural filters of soft tissue and joints. Passive vibration may also be effective, but it may or may not increase bone in the appropriate architectural pattern to oppose the forces of normal ambulatory activity. Effectiveness of high frequency mechanical stimulation in producing regional (muscle directed) bone response will be limited by 1. the sensitivity of bone to a particular range of frequencies and 2. the inertia of the muscles, limiting their response to external forces by increasing tension along insertions. We have begun mathematical modeling of normal ambulatory activity. Effectiveness of high frequency mechanical stimulation in producing regional (muscle directed) bone response will be limited by 1. the sensitivity of bone to a particular range of frequencies and 2. the inertia of the muscles, limiting their response to external forces by increasing tension along insertions. We have begun mathematical modeling of the rat forelimb as a transfer function between impact force and bone strain to predict optimal dynamic loading conditions for this system. We plan additional studies of mechanical counter-measures that incorporate improved dynamic loading, features relevant to anticipated evaluation of artificial gravity, exercise regimens and exposure to Martian gravity, The combination of mechanical countermeasures with ibandronate will also be investigated for signs of synergy.

Different effects on bone strength and cell differentiation in pre pubertal caloric restriction versus hypothalamic suppression✩,✩✩

PubMed Central

Joshi, R.N.; Safadi, F.F.; Barbe, M.F.; Carpio-Cano, Fe Del; Popoff, S.N.; Yingling, V.R.

2013-01-01

Hypothalamic amenorrhea and energy restriction during puberty affect peak bone mass accrual. One hypothesis suggests energy restriction alters hypothalamic function resulting in suppressed estradiol levels leading to bone loss. However, both positive and negative results have been reported regarding energy restriction and bone strength. Therefore, the purpose of this study was to investigate energy restriction and hypothalamic suppression during pubertal onset on bone mechanical strength and the osteogenic capacity of bone marrow-derived cells in two models: female rats treated with gonadotropin releasing hormone antagonists (GnRH-a) or 30% energy restriction. At 23 days of age, female Sprague Dawley rats were assigned to three groups: control group (C, n=10), GnRH-a group (n=10), and Energy Restriction (ER, n=12) group. GnRH-a animals received daily injections for 27 days. The animals in the ER group received 70% of the control animals’ intake. After sacrifice (50 days of age), body weight, uterine and muscle weights were measured. Bone marrow-derived stromal cells were cultured and assayed for proliferation and differentiation into osteoblasts. Outcome measures included bone strength, bone histomorphometry and architecture, serum IGF-1 and osteocalcin. GnRH-a suppressed uterine weight, decreased osteoblast proliferation, bone strength, trabecular bone volume and architecture compared to control. Elevated serum IGF-1 and osteocalcin levels and body weight were found. The ER model had an increase in osteoblast proliferation compared to the GnRH-a group, similar bone strength relative to body weight and increased trabecular bone volume in the lumbar spine compared to control. The ER animals were smaller but had developed bone strength sufficient for their size. In contrast, suppressed estradiol via hypothalamic suppression resulted in bone strength deficits and trabecular bone volume loss. In summary, our results support the hypothesis that during periods of nutritional stress the increased vertebral bone volume may be an adaptive mechanism to store mineral which differs from suppressed estradiol resulting from hypothalamic suppression. PMID:21807131

Limb bone morphology, bone strength, and cursoriality in lagomorphs

PubMed Central

Young, Jesse W; Danczak, Robert; Russo, Gabrielle A; Fellmann, Connie D

2014-01-01

The primary aim of this study is to broadly evaluate the relationship between cursoriality (i.e. anatomical and physiological specialization for running) and limb bone morphology in lagomorphs. Relative to most previous studies of cursoriality, our focus on a size-restricted, taxonomically narrow group of mammals permits us to evaluate the degree to which ‘cursorial specialization’ affects locomotor anatomy independently of broader allometric and phylogenetic trends that might obscure such a relationship. We collected linear morphometrics and μCT data on 737 limb bones covering three lagomorph species that differ in degree of cursoriality: pikas (Ochotona princeps, non-cursorial), jackrabbits (Lepus californicus, highly cursorial), and rabbits (Sylvilagus bachmani, level of cursoriality intermediate between pikas and jackrabbits). We evaluated two hypotheses: cursoriality should be associated with (i) lower limb joint mechanical advantage (i.e. high ‘displacement advantage’, permitting more cursorial species to cycle their limbs more quickly) and (ii) longer, more gracile limb bones, particularly at the distal segments (as a means of decreasing rotational inertia). As predicted, highly cursorial jackrabbits are typically marked by the lowest mechanical advantage and the longest distal segments, non-cursorial pikas display the highest mechanical advantage and the shortest distal segments, and rabbits generally display intermediate values for these variables. Variation in long bone robusticity followed a proximodistal gradient. Whereas proximal limb bone robusticity declined with cursoriality, distal limb bone robusticity generally remained constant across the three species. The association between long, structurally gracile limb bones and decreased maximal bending strength suggests that the more cursorial lagomorphs compromise proximal limb bone integrity to improve locomotor economy. In contrast, the integrity of distal limb bones is maintained with increasing cursoriality, suggesting that the safety factor takes priority over locomotor economy in those regions of the postcranial skeleton that experience higher loading during locomotion. Overall, these findings support the hypothesis that cursoriality is associated with a common suite of morphological adaptations across a range of body sizes and radiations. PMID:25046350

Nutritional Requirements for Space Station Freedom Crews

NASA Technical Reports Server (NTRS)

Lane, Helen W.; Rice, Barbara L.; Wogan, Christine F. (Editor)

1992-01-01

The purpose of this report was to set preliminary nutritional requirements for crewmembers flying from 90 to 180 day missions on Space Station Freedom. Specific recommendations included providing crewmembers with in flight feedback on nutritional intake, weight and strength, and incorporating issues of energy intake, body weight, body composition, strength, and protein intake in the flight medicine program. Exercise must be considered an integral part of any plan to maintain nutritional status, especially those modes that stress the skeleton and maintain body weight. Nutrient intake, amount of exercise, and drugs ingested must be recorded daily; high priority should be given to development of fully automated record systems that minimize astronauts' effort. A system of nutritional supplements should be developed to provide a method for reducing intake deficits that become apparent. Finally, post flight monitoring should include bone density, muscle mass and function, and iron status at three and six months after landing.

Increasing Bone Mass and Bone Strength in Individuals with Chronic Spinal Cord Injury: Maximizing Response to Therapy

DTIC Science & Technology

2017-10-01

Award Number: W81XWH-16-1-0763 TITLE: Increasing Bone Mass and Bone Strength in Individuals with Chronic Spinal Cord Injury: Maximizing Response...TYPE Annual 3. DATES COVERED (From - To) 30 Sep 2016-29 Sep 2017 5a. CONTRACT NUMBER Increasing Bone Mass and Bone Strength in Individuals with...DISTRIBUTION / AVAILABILITY STATEMENT Approved for public release; distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT Rapid bone loss is a universal

Bone geometry, strength, and muscle size in runners with a history of stress fracture.

PubMed

Popp, Kristin L; Hughes, Julie M; Smock, Amanda J; Novotny, Susan A; Stovitz, Steven D; Koehler, Scott M; Petit, Moira A

2009-12-01

Our primary aim was to explore differences in estimates of tibial bone strength, in female runners with and without a history of stress fractures. Our secondary aim was to explore differences in bone geometry, volumetric density, and muscle size that may explain bone strength outcomes. A total of 39 competitive distance runners aged 18-35 yr, with (SFX, n = 19) or without (NSFX, n = 20) a history of stress fracture were recruited for this cross-sectional study. Peripheral quantitative computed tomography (XCT 3000; Orthometrix, White Plains, NY) was used to assess volumetric bone mineral density (vBMD, mg x mm(-3)), bone area (ToA, mm(2)), and estimated compressive bone strength (bone strength index (BSI) = ToA x total volumetric density (ToD(2))) at the distal tibia (4%). Total (ToA, mm(2)) and cortical (CoA, mm(2)) bone area, cortical vBMD, and estimated bending strength (strength-strain index (SSIp), mm(3)) were measured at the 15%, 25%, 33%, 45%, 50%, and 66% sites. Muscle cross-sectional area (MCSA) was measured at the 50% and 66% sites. Participants in the SFX group had significantly smaller (7%-8%) CoA at the 45%, 50%, and 66% sites (P

The Soy Isoflavones to Reduce Bone Loss (SIRBL) Study: Three Year Effects on pQCT Bone Mineral Density and Strength Measures in Postmenopausal Women

USDA-ARS?s Scientific Manuscript database

Soy isoflavones exert inconsistent bone density preserving effects, but the bone strength preserving effects in humans are unknown. Our double-blind randomized controlled trial examined 2 soy isoflavone doses (80 or 120 mg/d) vs placebo tablets on volumetric bone mineral density (vBMD) and strength ...

Sublingual testosterone replacement improves muscle mass and strength, decreases bone resorption, and increases bone formation markers in hypogonadal men--a clinical research center study.

PubMed

Wang, C; Eyre, D R; Clark, R; Kleinberg, D; Newman, C; Iranmanesh, A; Veldhuis, J; Dudley, R E; Berman, N; Davidson, T; Barstow, T J; Sinow, R; Alexander, G; Swerdloff, R S

1996-10-01

To study the effects of androgen replacement therapy on muscle mass and strength and bone turnover markers in hypogonadal men, we administered sublingual testosterone (T) cyclodextrin (SLT; 5 mg, three times daily) to 67 hypogonadal men (baseline serum T, < 8.4 nmol/L) recruited from 4 centers in the U.S.: Torrance (n = 34), Durham (n = 12), New York (n = 9), and Salem (n = 12). Subjects who had received prior T therapy were withdrawn from injections for at least 6 weeks and from oral therapy for 4 weeks. Body composition, muscle strength, and serum and urinary bone turnover markers were measured before and after 6 months of SLT. We have shown previously that this regimen for 60 days will maintain adequate serum T levels and restore sexual function. Total body (P = 0.0104) and lean body mass (P = 0.007) increased with SLT treatment in the 34 subjects in whom body composition was assessed. There was no significant change in total body fat or percent fat. The increase in lean body mass was mainly in the legs; the right leg lean mass increased from 8.9 +/- 0.3 kg at 0 months to 9.2 +/- 0.3 kg at 6 months (P = 0.0008). This increase in leg lean mass was associated with increased leg muscle strength, assessed by leg press (0 months, 139.0 +/- 4.0 kg; 6 months, 147.7 +/- 4.2 kg; P = 0.0038). SLT replacement in hypogonadal men led to small, but significant, decreases in serum Ca (P = 0.0029) and the urinary calcium/creatinine ratio (P = 0.0066), which were associated with increases in serum PTH (P = 0.0001). At baseline, the urinary type I collagen-cross linked N-telopeptides/creatinine ratio [75.6 +/- 7.9 nmol bone collagen equivalents (BCE/mmol] was twice the normal adult male mean (41.0 +/- 3.6 nmol BCE/mmol) and was significantly decreased in response to SLT treatment at 6 months (68.2 +/- 7.7 nmol BCE/mmol; P = 0.0304) without significant changes in urinary creatinine. Serum skeletal alkaline phosphatase did not change. In addition, SLT replacement caused significant increases in serum osteocalcin (P = 0.0001) and type I procollagen (P = 0.0012). Bone mineral density did not change during the 6 months of SLT treatment. We conclude that SLT replacement therapy resulted in increases in lean muscle mass and muscle strength. Like estrogen replacement in hypogonadal postmenopausal females, androgen replacement therapy led to decreased bone resorption and urinary calcium excretion. Moreover, androgen replacement therapy may have the additional benefit of increasing bone formation. A longer term study for several years duration would be necessary to demonstrate whether these changes in bone turnover marker levels will result in increased bone mineral density decreased fracture risks, and reduced frailty in hypogonadal men.

Bonding strength of alkyl-2-cyanoacrylates to bone in vitro.

PubMed

Kilpikari, J; Lapinsuo, M; Törmälä, P; Pätiälä, H; Rokkanen, P

1986-10-01

This study measured the bonding strength between alkyl-2-cyanoacrylates and bone, and examined how treatment of the bone surface with acid, and prolonged exposure to moisture, affected this strength. The initial strength of all cyanoacrylates was high (9.6-11.2 N/mm2). In long-term experiments under water, n- and i-butylcyanoacrylates lost their strength at a far slower rate than ethylcyanoacrylates. However, the butylcyanoacrylates also showed a decrease of 15% in strength after three weeks. Pretreatment of the bone surface with acid did not have a marked effect on bonding strength, although SEM investigation revealed that the acid treatment had increased the porosity of the bone surface. A study of the fracture surface proved that the adhesive film tended to loosen or break after 3 to 6 weeks under water. The decrease in the bonding strength was probably due to the degradation of the adhesive film in water which loosened mechanical bonds between the bone and adhesive. Considering clinical use it would be necessary to achieve better long-term strength.

Maturity- and sex-related changes in tibial bone geometry, strength and bone-muscle strength indices during growth: a 20-month pQCT study.

PubMed

Macdonald, Heather M; Kontulainen, Saija A; Mackelvie-O'Brien, Kerry J; Petit, Moira A; Janssen, Patricia; Khan, Karim M; McKay, Heather A

2005-06-01

During growth, bone strength is conferred through subtle adaptations in bone mass and geometry in response to muscle forces. Few studies have examined the changes in bone geometry, strength and the bone-muscle strength relationship across maturity in boys and girls. Our aims were to describe (i) 20-month changes in bone geometry and strength at the tibial midshaft across three maturity groups of boys and girls, (ii) differences in these adaptations between sexes at the same approximate level of maturity and (iii) the bone-muscle strength relationship across maturity groups of boys and girls and between sexes. We used peripheral quantitative computed tomography (pQCT, Stratec XCT-2000) to measure change in total bone cross-sectional area (ToA, mm(2)), cortical area (CoA, mm(2)), average cortical thickness (C.Th., mm), section modulus (mm(3)) and muscle cross-sectional area (mm(2)) at the tibial midshaft (50% site) in 128 EARLY-, PERI- and POST-pubertal girls (n = 69, 11.9 +/- 0.6 years) and boys (n = 59, 12.0 +/- 0.6 years) across 20 months. We also calculated two bone-muscle strength indices (BMSI) for compression (CoA/MCSA) and bending [strength index/MCSA; where strength index = Z / (tibial length / 2)]. EARLY boys and girls had smaller ToA at baseline than same sex PERI or POST participants. There were no sex differences in ToA or CoA at baseline; however, boys increased both parameters significantly more than girls in every maturity group (8.5-11.1%, P < 0.01). These changes in bone geometry conferred greater gains in bone strength for boys compared with girls in each maturity group (13.8-15.6%, P < 0.01). Baseline BMSIs did not differ between sexes for EARLY and PERI groups, whereas BMSIs were significantly higher for POST boys compared with POST girls (P < 0.05). BMSIs decreased for EARLY and PERI girls (-7.4-(-1.1%)) whereas the ratios remained stable for EARLY and PERI boys (-0.6-2.5%). This sex difference in BMSI change was due to a relatively greater increase in CoA among EARLY and PERI boys compared with same-maturity girls. BMSIs remained stable in POST girls and decreased in POST boys due to relatively greater gains in MCSA. This study provides novel longitudinal descriptions of the maturity- and sex-specific changes in bone geometry, strength and bone-muscle strength indices.

Enhanced bone screw fixation with biodegradable bone cement in osteoporotic bone model.

PubMed

Juvonen, Tiina; Koistinen, Arto; Kröger, Heikki; Lappalainen, Reijo

2012-09-27

The purpose of this study was to study the potential of novel biodegradable PCL bone cement to improve bone screw fixation strength in osteoporotic bone. The biomechanical properties of bone cement (ε-polycaprolactone, PCL) and fixation strength were studied using biomechanical tests and bone screws fixed in an osteoporotic bone model. Removal torques and pullout strengths were assessed for cortical, self-tapping, and cancellous screws inserted in the osteoporotic bone model (polyurethane foam blocks with polycarbonate plate) with and without PCL bone cement. Open cell and cellular rigid foam blocks with a density of 0.12 g/cm3 were used in this model. Removal torques were significantly (more than six-fold) improved with bone cement for cancellous screws. Furthermore, the bone cement improved pullout strengths three to 12 times over depending on the screw and model material. Biodegradable bone cement turned out to be a very potential material to stabilize screw fixation in osteoporotic bone. The results warrant further research before safe clinical use, especially to clarify clinically relevant factors using real osteoporotic bone under human body conditions and dynamic fatigue testing for long-term performance.

Structural Strength Benefits Observed at the Hip of Premenarcheal Gymnasts Are Maintained Into Young Adulthood 10 Years After Retirement From the Sport.

PubMed

Erlandson, Marta C; Runalls, Shonah B; Jackowski, Stefan A; Faulkner, Robert A; Baxter-Jones, Adam D G

2017-11-01

Premenarcheal female gymnasts have been consistently found to have greater bone mass and structural advantages. However, little is known about whether these structural advantages are maintained after the loading stimulus is removed. Therefore, the purpose of this study was to investigate the structural properties at the hip after long-term retirement from gymnastics. Structural properties were derived from dual-energy X-ray absorptiometry scans using the hip structural analysis program for the same 24 gymnasts and 21 nongymnasts both in adolescence (8-15 y) and adulthood (22-30 y). Structural measures were obtained at the narrow neck, intertrochanter, and femoral shaft and included cross-sectional area, section modulus, and buckling ratio. Multivariate analysis of covariance was used to assess differences between groups in bone measures while controlling for size, age, maturity, and physical activity. Gymnasts were found to have structural advantages at the narrow neck in adolescence (16% greater cross-sectional area, 17% greater section modulus, and 25% lower buckling ratio) and 14 years later (13% greater cross-sectional area and 26% lower buckling ratio). Benefits were also found at the intertrochanter and femoral shaft sites in adolescence and adulthood. Ten years after retirement from gymnastics, former gymnasts' maintained significantly better hip bone structure than females who did not participate in gymnastics during growth.

Physical activity, but not sedentary time, influences bone strength in late adolescence.

PubMed

Tan, Vina Ps; Macdonald, Heather M; Gabel, Leigh; McKay, Heather A

2018-03-20

Physical activity is essential for optimal bone strength accrual, but we know little about interactions between physical activity, sedentary time, and bone outcomes in older adolescents. Physical activity (by accelerometer and self-report) positively predicted bone strength and the distal and midshaft tibia in 15-year-old boys and girls. Lean body mass mediated the relationship between physical activity and bone strength in adolescents. To examine the influence of physical activity (PA) and sedentary time on bone strength, structure, and density in older adolescents. We used peripheral quantitative computed tomography to estimate bone strength at the distal tibia (8% site; bone strength index, BSI) and tibial midshaft (50% site; polar strength strain index, SSI p ) in adolescent boys (n = 86; 15.3 ± 0.4 years) and girls (n = 106; 15.3 ± 0.4 years). Using accelerometers (GT1M, Actigraph), we measured moderate-to-vigorous PA (MVPA Accel ), vigorous PA (VPA Accel ), and sedentary time in addition to self-reported MVPA (MVPA PAQ-A ) and impact PA (ImpactPA PAQ-A ). We examined relations between PA and sedentary time and bone outcomes, adjusting for ethnicity, maturity, tibial length, and total body lean mass. At the distal tibia, MVPA Accel and VPA Accel positively predicted BSI (explained 6-7% of the variance, p < 0.05). After adjusting for lean mass, only VPA Accel explained residual variance in BSI. At the tibial midshaft, MVPA Accel , but not VPA Accel , positively predicted SSI p (explained 3% of the variance, p = 0.01). Lean mass attenuated this association. MVPA PAQ-A and ImpactPA PAQ-A also positively predicted BSI and SSI p (explained 2-4% of the variance, p < 0.05), but only ImpactPA PAQ-A explained residual variance in BSI after accounting for lean mass. Sedentary time did not independently predict bone strength at either site. Greater tibial bone strength in active adolescents is mediated, in part, by lean mass. Despite spending most of their day in sedentary pursuits, adolescents' bone strength was not negatively influenced by sedentary time.

Shape Optimization of Bone-Bonding Subperiosteal Devices with Finite Element Analysis.

PubMed

Ogasawara, Takeshi; Uezono, Masayoshi; Takakuda, Kazuo; Kikuchi, Masanori; Suzuki, Shoichi; Moriyama, Keiji

2017-01-01

Subperiosteal bone-bonding devices have been proposed for less invasive treatments in orthodontics. The device is osseointegrated onto a bone surface without fixation screws and is expected to rapidly attain a bone-bonding strength that successfully meets clinical performance. Hence, the device's optimum shape for rapid and strong bone bonding was examined in this study by finite element analyses. First, a stress analysis was performed for a circular rod device with an orthodontic force parallel to the bone surface, and the estimate of the bone-bonding strength based on the bone fracture criterion was verified with the results of an animal experiment. In total, four cross-sectional rod geometries were investigated: circular (Cr), elliptical (El), semicircular (Sc), and rectangular (Rc). By changing the height of the newly formed bone to mimic the progression of new bone formation, the estimation of the bone-bonding strength was repeated for each geometry. The rod with the Rc cross section exhibited the best performance, followed by those with the Sc, El, and Cr cross sections, from the aspects of the rapid acquisition of strength and the strength itself. Thus, the rectangular cross section is the best for rod-like subperiosteal devices for rapid bone bonding.

Adult bone strength of children from single-parent families: the Midlife in the United States Study.

PubMed

Crandall, C J; Karlamangla, A S; Merkin, S S; Binkley, N; Carr, D; Greendale, G A; Seeman, T E

2015-03-01

Bone health may be negatively impacted by childhood socio-environmental circumstances. We examined the independent associations of single-parent childhood and parental death or divorce in childhood with adult bone strength indices. Longer exposure to a single-parent household in childhood was associated with lower bone strength in adulthood. Because peak bone mass is acquired during childhood, bone health may be negatively impacted by childhood socio-environmental disadvantage. The goal of this study was to determine whether being raised in a single-parent household is associated with lower bone strength in adulthood. Using dual-energy X-ray absorptiometry data from 708 participants (mean age 57 years) in the Midlife in the United States Biomarker Project, we examined the independent associations of composite indices of femoral neck bone strength relative to load (in three failure modes: compression, bending, and impact) in adulthood with the experience of single-parent childhood and parental death or divorce in childhood. After adjustment for gender, race, menopause transition stage, age, and body mass index, each additional year of single-parent childhood was associated with 0.02 to 0.03 SD lower indices of adult femoral neck strength. In those with 9-16 years of single-parent childhood, the compression strength index was 0.41 SD lower, bending strength index was 0.31 SD lower, and impact strength index was 0.25 SD lower (all p values < 0.05). In contrast, parental death or divorce during childhood was not by itself independently associated with adult bone strength indices. The magnitudes of these associations were unaltered by additional adjustment for lifestyle factors and socioeconomic status in childhood and adulthood. Independent of parental death or divorce, growing up in a single-parent household is associated with lower femoral neck bone strength in adulthood, and this association is not entirely explained by childhood or adult socioeconomic conditions or lifestyle choices.

Micro-MRI-based image acquisition and processing system for assessing the response to therapeutic intervention

NASA Astrophysics Data System (ADS)

Vasilić, B.; Ladinsky, G. A.; Saha, P. K.; Wehrli, F. W.

2006-03-01

Osteoporosis is the cause of over 1.5 million bone fractures annually. Most of these fractures occur in sites rich in trabecular bone, a complex network of bony struts and plates found throughout the skeleton. The three-dimensional structure of the trabecular bone network significantly determines mechanical strength and thus fracture resistance. Here we present a data acquisition and processing system that allows efficient noninvasive assessment of trabecular bone structure through a "virtual bone biopsy". High-resolution MR images are acquired from which the trabecular bone network is extracted by estimating the partial bone occupancy of each voxel. A heuristic voxel subdivision increases the effective resolution of the bone volume fraction map and serves a basis for subsequent analysis of topological and orientational parameters. Semi-automated registration and segmentation ensure selection of the same anatomical location in subjects imaged at different time points during treatment. It is shown with excerpts from an ongoing clinical study of early post-menopausal women, that significant reduction in network connectivity occurs in the control group while the structural integrity is maintained in the hormone replacement group. The system described should be suited for large-scale studies designed to evaluate the efficacy of therapeutic intervention in subjects with metabolic bone disease.

High-strength mineralized collagen artificial bone

NASA Astrophysics Data System (ADS)

Qiu, Zhi-Ye; Tao, Chun-Sheng; Cui, Helen; Wang, Chang-Ming; Cui, Fu-Zhai

2014-03-01

Mineralized collagen (MC) is a biomimetic material that mimics natural bone matrix in terms of both chemical composition and microstructure. The biomimetic MC possesses good biocompatibility and osteogenic activity, and is capable of guiding bone regeneration as being used for bone defect repair. However, mechanical strength of existing MC artificial bone is too low to provide effective support at human load-bearing sites, so it can only be used for the repair at non-load-bearing sites, such as bone defect filling, bone graft augmentation, and so on. In the present study, a high strength MC artificial bone material was developed by using collagen as the template for the biomimetic mineralization of the calcium phosphate, and then followed by a cold compression molding process with a certain pressure. The appearance and density of the dense MC were similar to those of natural cortical bone, and the phase composition was in conformity with that of animal's cortical bone demonstrated by XRD. Mechanical properties were tested and results showed that the compressive strength was comparable to human cortical bone, while the compressive modulus was as low as human cancellous bone. Such high strength was able to provide effective mechanical support for bone defect repair at human load-bearing sites, and the low compressive modulus can help avoid stress shielding in the application of bone regeneration. Both in vitro cell experiments and in vivo implantation assay demonstrated good biocompatibility of the material, and in vivo stability evaluation indicated that this high-strength MC artificial bone could provide long-term effective mechanical support at human load-bearing sites.

The Influence of Cement Morphology Parameters on the Strength of the Cement-Bone Interface in Tibial Tray Fixation.

PubMed

Nagel, Katrin; Bishop, Nicholas E; Schlegel, Ulf J; Püschel, Klaus; Morlock, Michael M

2017-02-01

The strength of the cement-bone interface in tibial component fixation depends on the morphology of the cement mantle. The purpose of this study was to identify thresholds of cement morphology parameters to maximize fixation strength using a minimum amount of cement. Twenty-three cadaveric tibiae were analyzed that had been implanted with tibial trays in previous studies and for which the pull-out strength of the tray had been measured. Specimens were separated into a group failing at the cement-bone interface (INTERFACE) and one failing in the bulk bone (BULK). Maximum pull-out strength corresponds to the ultimate strength of the bulk bone if the cement-bone interface is sufficiently strong. 3D models of the cement mantle in situ were reconstructed from computed tomography scans. The influences of bone mineral density and 6 cement morphology parameters (reflecting cement penetration, bone-cement interface, cement volume) on pull-out strength of the BULK group were determined using multiple regression analysis. The threshold of each parameter for classification of the specimens into either group was determined using receiver operating characteristic analysis. Cement penetration exceeding a mean of 1.1 mm or with a maximum of 5.6 mm exclusively categorized all BULK bone failure specimens. Failure strength of BULK failure specimens increased with bone mineral density (R 2  = 0.67, P < .001) but was independent of the cement morphology parameters. To maximize fixation strength, a mean cement penetration depth of at least 1.1 mm should be achieved during tibial tray cementing. Copyright © 2016 Elsevier Inc. All rights reserved.

Decreased bone turnover with balanced resorption and formation prevent cortical bone loss during disuse (hibernation) in grizzly bears (Ursus arctos horribilis).

PubMed

McGee, Meghan E; Maki, Aaron J; Johnson, Steven E; Nelson, O Lynne; Robbins, Charles T; Donahue, Seth W

2008-02-01

Disuse uncouples bone formation from resorption, leading to increased porosity, decreased bone geometrical properties, and decreased bone mineral content which compromises bone mechanical properties and increases fracture risk. However, black bear bone properties are not adversely affected by aging despite annual periods of disuse (i.e., hibernation), which suggests that bears either prevent bone loss during disuse or lose bone and subsequently recover it at a faster rate than other animals. Here we show decreased cortical bone turnover during hibernation with balanced formation and resorption in grizzly bear femurs. Hibernating grizzly bear femurs were less porous and more mineralized, and did not demonstrate any changes in cortical bone geometry or whole bone mechanical properties compared to active grizzly bear femurs. The activation frequency of intracortical remodeling was 75% lower during hibernation than during periods of physical activity, but the normalized mineral apposition rate was unchanged. These data indicate that bone turnover decreases during hibernation, but osteons continue to refill at normal rates. There were no changes in regional variation of porosity, geometry, or remodeling indices in femurs from hibernating bears, indicating that hibernation did not preferentially affect one region of the cortex. Thus, grizzly bears prevent bone loss during disuse by decreasing bone turnover and maintaining balanced formation and resorption, which preserves bone structure and strength. These results support the idea that bears possess a biological mechanism to prevent disuse osteoporosis.

Whole bone mechanics and bone quality.

PubMed

Cole, Jacqueline H; van der Meulen, Marjolein C H

2011-08-01

The skeleton plays a critical structural role in bearing functional loads, and failure to do so results in fracture. As we evaluate new therapeutics and consider treatments to prevent skeletal fractures, understanding the basic mechanics underlying whole bone testing and the key principles and characteristics contributing to the structural strength of a bone is critical. We therefore asked: (1) How are whole bone mechanical tests performed and what are the key outcomes measured? (2) How do the intrinsic characteristics of bone tissue contribute to the mechanical properties of a whole bone? (3) What are the effects of extrinsic characteristics on whole bone mechanical behavior? (4) Do environmental factors affect whole bone mechanical properties? We conducted a PubMed search using specific search terms and limiting our included articles to those related to in vitro testing of whole bones. Basic solid mechanics concepts are summarized in the context of whole bone testing and the determinants of whole bone behavior. Whole bone mechanical tests measure structural stiffness and strength from load-deformation data. Whole bone stiffness and strength are a function of total bone mass and the tissue geometric distribution and material properties. Age, sex, genetics, diet, and activity contribute to bone structural performance and affect the incidence of skeletal fractures. Understanding and preventing skeletal fractures is clinically important. Laboratory tests of whole bone strength are currently the only measures for in vivo fracture prediction. In the future, combined imaging and engineering models may be able to predict whole bone strength noninvasively.

Lower Body Negative Pressure Treadmill Exercise and Resistive Exercise Countermeasures Maintain Physiologic Function in Women during Simulated Microgravity

NASA Technical Reports Server (NTRS)

Macias, B. R.; Schneider, S. M.; Lee, S. M. C.; Guinet, P.; Hughson, R. L.; Smith, Scott M.; Watenpaugh, D. E.; Hargens, A. R.

2008-01-01

We hypothesized that supine LBNP treadmill exercise combined with Flywheel resistive exercise maintains upright physiologic responses following 60-days of head-down tilt (HDT) bed rest (BR). METHODS: 16 healthy women (age 25-40 years) underwent 60-days HDT (-6deg.) BR. Women were assigned to either a non-exercise control group (CON, n=8) or to an exercise group (EX, n=8). EX subjects performed a 40-min, variable intensity LBNP exercise protocol at foot-ward forces between 1.0-1.1 times body weight, followed by 10- min of resting LBNP 3-4 days/week. Resistive exercise of maximal concentric and eccentric supine leg press and heel raise exercises were performed using a flywheel ergometer 2-3 days/week. IRBs approved this study with informed/written consent. RESULTS: Post-BR VO2pk was not different in EX (-3.3+/-1.2%) but decreased significantly in CON (-21.2+/-2.1%), p< 0.05. Post-BR orthostatic tolerance time (mean se) decreased significantly less in EX (19.3+/-1.3 to 14.4+/-1.5 min) than in CON (17.5+/-0.1 to 9.1+/- 1.5 min), p=0.03. Post-BR muscle strength decreased significantly in CON, but was preserved in EX. Post-BR bone resorption was greater than pre-BR in both groups (p<0.05). Bone formation markers, were significantly elevated (p<0.05) in EX than in CON. CONCLUSIONS: Supine LBNP treadmill exercise along with flywheel resistive exercise maintains upright exercise capacity, orthostatic responses and muscle strength during 60-days HDT BR.

Reduced diaphyseal strength associated with high intracortical vascular porosity within long bones of children with Osteogenesis Imperfecta

PubMed Central

Jameson, John; Smith, Peter; Harris, Gerald

2015-01-01

Osteogenesis Imperfecta is a genetic disorder resulting in bone fragility. The mechanisms behind this fragility are not well understood. In addition to characteristic bone mass deficiencies, research suggests that bone material properties are compromised in individuals with this disorder. However, little data exists regarding bone properties beyond the microstructural scale in individuals with this disorder. Specimens were obtained from long bone diaphyses of nine children with osteogenesis imperfecta during routine osteotomy procedures. Small rectangular beams, oriented longitudinally and transversely to the diaphyseal axis, were machined from these specimens and elastic modulus, yield strength, and maximum strength were measured in three-point bending. Intracortical vascular porosity, bone volume fraction, osteocyte lacuna density, and volumetric tissue mineral density were determined by synchrotron micro-computed tomography, and relationships among these mechanical properties and structural parameters were explored. Modulus and strength were on average 64–68% lower in the transverse vs. longitudinal beams (P<0.001, linear mixed model). Vascular porosity ranged between 3–42% of total bone volume. Longitudinal properties were associated negatively with porosity (P≤0.006, linear regressions). Mechanical properties, however, were not associated with osteocyte lacuna density or volumetric tissue mineral density (P≥0.167). Bone properties and structural parameters were not associated significantly with donor age (p≥0.225, linear mixed models). This study presents novel data regarding bone material strength in children with osteogenesis imperfecta. Results confirm that these properties are anisotropic. Elevated vascular porosity was observed in most specimens, and this parameter was associated with reduced bone material strength. These results offer insight towards understanding bone fragility and the role of intracortical porosity on the strength of bone tissue in children with osteogenesis imperfecta. PMID:24928496

Reduced diaphyseal strength associated with high intracortical vascular porosity within long bones of children with osteogenesis imperfecta.

PubMed

Albert, Carolyne; Jameson, John; Smith, Peter; Harris, Gerald

2014-09-01

Osteogenesis imperfecta is a genetic disorder resulting in bone fragility. The mechanisms behind this fragility are not well understood. In addition to characteristic bone mass deficiencies, research suggests that bone material properties are compromised in individuals with this disorder. However, little data exists regarding bone properties beyond the microstructural scale in individuals with this disorder. Specimens were obtained from long bone diaphyses of nine children with osteogenesis imperfecta during routine osteotomy procedures. Small rectangular beams, oriented longitudinally and transversely to the diaphyseal axis, were machined from these specimens and elastic modulus, yield strength, and maximum strength were measured in three-point bending. Intracortical vascular porosity, bone volume fraction, osteocyte lacuna density, and volumetric tissue mineral density were determined by synchrotron micro-computed tomography, and relationships among these mechanical properties and structural parameters were explored. Modulus and strength were on average 64-68% lower in the transverse vs. longitudinal beams (P<0.001, linear mixed model). Vascular porosity ranged between 3 and 42% of total bone volume. Longitudinal properties were associated negatively with porosity (P≤0.006, linear regressions). Mechanical properties, however, were not associated with osteocyte lacuna density or volumetric tissue mineral density (P≥0.167). Bone properties and structural parameters were not associated significantly with donor age (P≥0.225, linear mixed models). This study presents novel data regarding bone material strength in children with osteogenesis imperfecta. Results confirm that these properties are anisotropic. Elevated vascular porosity was observed in most specimens, and this parameter was associated with reduced bone material strength. These results offer insight toward understanding bone fragility and the role of intracortical porosity on the strength of bone tissue in children with osteogenesis imperfecta. Copyright © 2014 Elsevier Inc. All rights reserved.

Physical performance in relation to body composition and bone mineral density in healthy, overweight, and obese postmenopausal women.

PubMed

Shin, Hyehyung; Liu, Pei-Yang; Panton, Lynn B; Ilich, Jasminka Z

2014-01-01

Diminished physical performance can be detrimental among the older adults, causing falls and subsequent fractures, loss of independence, and increased morbidity and mortality rates. Therefore, it is important to maintain functional ability from the early onset of aging. The purpose of this study was to investigate the relationship between physical performance measures and body composition (bone, fat, and lean mass) in healthy, overweight and obese, early postmenopausal white women. A total of 97 participants aged 56.0 (4.4) years (mean (SD)) with body mass index of 31.0 (4.6) kg/m(2) were included. Weight and height were recorded and 3 days of dietary records and physical activity were collected. Dual-energy x-ray absorptiometry measurements for body composition and bone mineral density were performed. Fasting blood samples were used for serum 25-hydroxy vitamin D (25OHD) analysis. Measures of physical performance included handgrip strength, 8-meter walking speed, one-leg-stance time, 8-foot Timed Get-Up-and-Go Test, and chair sit-to-stand test. Results showed that higher lean mass was related to better physical performance on items assessing body strength, including handgrip (r ranged from 0.22 to 0.25, P < .05) while higher body fat was related to the poorer physical performance in each of the assessed measures. Bone mineral density of the forearm was positively related to the handgrip strength (r = 0.207, P < .05). In regression analyses (controlled for age, weight, height, serum 25OHD status, calcium intake, physical activity, and smoking), fat mass of the lower extremities was inversely related to walking speed, one-leg-stance time, and Get-Up-and-Go measures, all crucial for mobility (r(2) = 0.13-0.23, P < .05). Overall, higher fat and lower lean mass was related to poorer physical performance, while forearm bone mineral density was related to the handgrip strength only. Further investigation may be beneficial for a better understanding of how body composition may prevent decline in physical performance among overweight/obese, mid-age, and older women.

Mechanical torque measurement for in vivo quantification of bone strength in the proximal femur.

PubMed

Mueller, Marc Andreas; Hengg, Clemens; Hirschmann, Michael; Schmid, Denise; Sprecher, Christoph; Audigé, Laurent; Suhm, Norbert

2012-10-01

Bone strength determines fracture risk and fixation strength of osteosynthesis implants. In vivo, bone strength is currently measured indirectly by quantifying bone mineral density (BMD) which is however only one determinant of the bone's biomechanical competence besides the bone's macro- and micro-architecture and tissue related parameters. We have developed a measurement principle (DensiProbe™ Hip) for direct, mechanical quantification of bone strength within the proximal femur upon hip fracture fixation. Previous cadaver tests indicated a close correlation between DensiProbe™ Hip measurements, 3D micro-CT analysis and biomechanical indicators of bone strength. The goal of this study was to correlate DensiProbe™ Hip measurements with areal bone mineral density (BMD). Forty-three hip fracture patients were included in this study. Intraoperatively, DensiProbe™ Hip was inserted to the subsequent hip screw tip position within the femoral head. Peak torque to breakaway of local cancellous bone was registered. Thirty-seven patients underwent areal BMD measurements of the contralateral proximal femur. Failure of fixation was assessed radio graphically 6 and 12 weeks postoperatively. Peak torque and femoral neck BMD showed significant correlations (R=0.60, P=0.0001). In regression analysis, areal BMD explained 46% of femoral neck BMD variance in a quadratic relationship. Throughout the 12-week follow-up period, no failure of fixation was observed. DensiProbe™ Hip may capture variations of bone strength beyond areal BMD which are currently difficult to measure in vivo. A multicenter study will clarify if peak torque predicts fixation failure. Copyright © 2012 Elsevier Ltd. All rights reserved.

Osteocytes Mechanosensing in NASA Rotating Wall Bioreactor

NASA Technical Reports Server (NTRS)

Spatz, Jordan; Sibonga, Jean; Wu, Honglu; Barry, Kevin; Bouxsein, Mary; Pajevic, Paola Divieti

2010-01-01

Osteocyte cells are the most abundant (90%) yet least understood bone cell type in the human body. Osteocytes are theorized to be the mechanosensors and transducers of mechanical load for bones, yet the biological mechanism of this action remains elusive. However, recent discoveries in osteocyte cell biology have shed light on their importance as key mechanosensing cells regulating bone remodeling and phosphate homeostasis. The aim of this project was to characterize gene expression patterns and protein levels following exposure of MLO-Y4, a very well characterized murine osteocyte-like cell line, to simulated microgravity using the NASA Rotating Wall Vessel (RWV) Bioreactor. To determine mechanistic pathways of the osteocyte's gravity sensing ability, we evaluated in vitro gene and protein expression of osteocytes exposed to simulated microgravity. Improved understanding of the fundamental mechanisms of mechano transduction at the osteocyte cellular level may lead to revolutionary treatment otions to mitigate the effects of bone loss encountered by astronauts on long duration space missions and provide tailored treatment options for maintaining bone strength of immobilized/partially paralyzed patients here on Earth.

Bone strength in pure bending: bearing of geometric and material properties.

PubMed

Winter, Werner

2008-01-01

Osteoporosis is characterized by decreasing of bone mass and bone strength with advanced age. For characterization of material properties of dense and cellular bone the volumetric bone mineral density (vBMD) is one of the most important contributing factors to bone strength. Often bending tests of whole bone are used to get information about the state of osteoporosis. In a first step, different types of cellular structures are considered to characterize vBMD and its influence to elastic and plastic material properties. Afterwards, the classical theory of plastic bending is used to describe the non-linear moment-curvature relation of a whole bone. For bending of whole bone with sandwich structure an effective second moment of area can be defined. The shape factor as a pure geometrical value is considered to define bone strength. This factor is discussed for a bone with circular cross section and different thickness of cortical bone. The deduced relations and the decrease of material properties are used to demonstrate the influence of osteoporosis to bone bending strength. It can be shown that the elastic and plastic material properties of bone are related to a relative bone mineral density. Starting from an elastic-plastic bone behavior with an constant yield stress the non-linear moment-curvature relation in bending is related to yielding of the fibres in the cross section. The ultimate moment is characterized by a shape factor depending on the geometry of the cross section and on the change of cortical thickness.

Peak bone strength is influenced by calcium intake in growing rats.

PubMed

Viguet-Carrin, S; Hoppler, M; Membrez Scalfo, F; Vuichoud, J; Vigo, M; Offord, E A; Ammann, P

2014-11-01

In this study we investigated the effect of supplementing the diet of the growing male rat with different levels of calcium (from low to higher than recommended intakes at constant Ca/P ratio), on multiple factors (bone mass, strength, size, geometry, material properties, turnover) influencing bone strength during the bone accrual period. Rats, age 28days were supplemented for 4weeks with high Ca (1.2%), adequate Ca (0.5%) or low Ca level (0.2%). Bone metabolism and structural parameters were measured. No changes in body weight or food intake were observed among the groups. As anticipated, compared to the adequate Ca intake, low-Ca intake had a detrimental impact on bone growth (33.63 vs. 33.68mm), bone strength (-19.7% for failure load), bone architecture (-58% for BV/TV) and peak bone mass accrual (-29% for BMD) due to the hormonal disruption implied in Ca metabolism. In contrast, novel, surprising results were observed in that higher than adequate Ca intake resulted in improved peak bone strength (106 vs. 184N/mm for the stiffness and 61 vs. 89N for the failure load) and bone material properties (467 vs. 514mPa for tissue hardness) but these effects were not accompanied by changes in bone mass, size, microarchitecture or bone turnover. Hormonal factors, IGF-I and bone modeling were also evaluated. Compared to the adequate level of Ca, IGF-I level was significantly lower in the low-Ca intake group and significantly higher in the high-Ca intake group. No detrimental effects of high Ca were observed on bone modeling (assessed by histomorphometry and bone markers), at least in this short-term intervention. In conclusion, the decrease in failure load in the low calcium group can be explained by the change in bone geometry and bone mass parameters. Thus, improvements in mechanical properties can be explained by the improved quality of intrinsic bone tissue as shown by nanoindentation. These results suggest that supplemental Ca may be beneficial for the attainment of peak bone strength and that multiple factors linked to bone mass and strength should be taken into account when setting dietary levels of adequate mineral intake to support optimal peak bone mass acquisition. Copyright © 2014 Elsevier Inc. All rights reserved.

Is there a role for exercise in the prevention of osteoporotic fractures?

PubMed

Rutherford, O M

1999-12-01

To examine whether there is a role for exercise in improving bone mineral density (BMD), particularly in postmenopausal women. The effects of different types of exercise are examined together with their effects at selected skeletal sites. The role of activity in reducing falls and hip fractures will also be considered as well as the potentially negative effects of excessive exercise. A literature search over the past 20 years was conducted and landmark papers selected. Certain types of exercise have been found to exert moderate benefits on BMD of the wrist, spine, and hip. Most studies do not detect a difference between the effects of endurance activities and strength training for BMD of the spine. It has been more difficult to isolate the optimal type of activity for effecting an osteogenic response at the hip, but recent evidence suggests that high impact work such as stepping and jumping may be effective at this site. The combination of hormone replacement therapy and exercise would appear to be more effective than either intervention on its own. Certain types of exercises have additional benefits, such as muscle strengthening, which could reduce the incidence of falls. Excessive exercise can lead to menstrual disturbances in female athletes and this in turn can cause bone loss, particularly from the spine. Exercise across the life span should be encouraged in order to maximise peak bone mass, reduce age related bone loss, and maintain muscle strength and balance. Although the effects of exercise on BMD later in life are small, epidemiological evidence suggests that being active can nearly halve the incidence of hip fractures in the older population. This effect is most probably multifactorial through the positive effects on bone, muscle strength, balance, and joint flexibility. Younger women should be aware of the dangers to the skeleton of menstrual disorders.

Remnant Woven Bone and Calcified Cartilage in Mouse Bone: Differences between Ages/Sex and Effects on Bone Strength

PubMed Central

Ip, Victoria; Toth, Zacharie; Chibnall, John; McBride-Gagyi, Sarah

2016-01-01

Introduction Mouse models are used frequently to study effects of bone diseases and genetic determinates of bone strength. Murine bones have an intracortical band of woven bone that is not present in human bones. This band is not obvious under brightfield imaging and not typically analyzed. Due to the band’s morphology and location it has been theorized to be remnant bone from early in life. Furthermore, lamellar and woven bone are well known to have differing mechanical strengths. The purpose of this study was to determine (i) if the band is from early life and (ii) if the woven bone or calcified cartilage contained within the band affect whole bone strength. Woven Bone Origin Studies In twelve to fourteen week old mice, doxycycline was used to label bone formed prior to 3 weeks old. Doxycycline labeling and woven bone patterns on contralateral femora matched well and encompassed an almost identical cross-sectional area. Also, we highlight for the first time in mice the presence of calcified cartilage exclusively within the band. However, calcified cartilage could not be identified on high resolution cone-beam microCT scans when examined visually or by thresholding methods. Mechanical Strength Studies Subsequently, three-point bending was used to analyze the effects of woven bone and calcified cartilage on whole bone mechanics in a cohort of male and female six and 13 week old Balb/C mice. Three-point bending outcomes were correlated with structural and compositional measures using multivariate linear regression. Woven bone composed a higher percent of young bones than older bones. However, calcified cartilage in older bones was twice that of younger bones, which was similar when normalized by area. Area and/or tissue mineral density accounted for >75% of variation for most strength outcomes. Percent calcified cartilage added significant predictive power to maximal force and bending stress. Calcified cartilage and woven bone could have more influence in genetic models where calcified cartilage percent is double our highest value. PMID:27829059

Bone Biomarkers on the Pathway to Effective Spaceflight Countermeasures

NASA Technical Reports Server (NTRS)

Spatz, Jordan

2009-01-01

Osteocyte cells are the most abundant yet least understood bone cell type in the human body. However, recent discovers in osteocyte cell biology have shed light on their importance as key mechanosensing cells regulating the bone remodeling process. Thus, we propose the first ever in vitro gene expression evaluation of osteocytes exposed to simulated microgravity to determine mechanistic pathways of their gravity sensing ability. Improved understanding of the fundamental mechanisms at the osteocyte cellular level may lead to improved treatment options to mitigate the effects of bone loss encountered by astronauts on long duration space missions and provide tailored treatment options for maintaining bone strength of immobilized/partially paralyzed patients here on Earth. Aim 1: Characterize the gene expression patterns and protein levels following exposure of murine osteocytelike cell line (MLO-Y4) to simulated microgravity using the NASA Rotating Wall Vessel (RWV) Bioreactor. Osteocytes are theorized to be the mechanosensors and transducers of mechanical load for bones, yet the biological mechanism of this action remains elusive. We propose to investigate the genetic regulation of the mechanism of the MLO-Y4 cell in the NASA Bioreactor as it is the accepted ground-based analog for simulating vector averaged microgravity.

3D printing of high-strength bioscaffolds for the synergistic treatment of bone cancer

NASA Astrophysics Data System (ADS)

Ma, Hongshi; Li, Tao; Huan, Zhiguang; Zhang, Meng; Yang, Zezheng; Wang, Jinwu; Chang, Jiang; Wu, Chengtie

2018-04-01

The challenges in bone tumor therapy are how to repair the large bone defects induced by surgery and kill all possible residual tumor cells. Compared to cancellous bone defect regeneration, cortical bone defect regeneration has a higher demand for bone substitute materials. To the best of our knowledge, there are currently few bifunctional biomaterials with an ultra-high strength for both tumor therapy and cortical bone regeneration. Here, we designed Fe-CaSiO3 composite scaffolds (30CS) via 3D printing technique. First, the 30CS composite scaffolds possessed a high compressive strength that provided sufficient mechanical support in bone cortical defects; second, synergistic photothermal and ROS therapies achieved an enhanced tumor therapeutic effect in vitro and in vivo. Finally, the presence of CaSiO3 in the composite scaffolds improved the degradation performance, stimulated the proliferation and differentiation of rBMSCs, and further promoted bone formation in vivo. Such 30CS scaffolds with a high compressive strength can function as versatile and efficient biomaterials for the future regeneration of cortical bone defects and the treatment of bone cancer.

Challenges of Estimating Fracture Risk with DXA: Changing Concepts About Bone Strength and Bone Density.

PubMed

Licata, Angelo A

2015-07-01

Bone loss due to weightlessness is a significant concern for astronauts' mission safety and health upon return to Earth. This problem is monitored with bone densitometry (DXA), the clinical tool used to assess skeletal strength. DXA has served clinicians well in assessing fracture risk and has been particularly useful in diagnosing osteoporosis in the elderly postmenopausal population for which it was originally developed. Over the past 1-2 decades, however, paradoxical and contradictory findings have emerged when this technology was widely employed in caring for diverse populations unlike those for which it was developed. Although DXA was originally considered the surrogate marker for bone strength, it is now considered one part of a constellation of factors-described collectively as bone quality-that makes bone strong and resists fracturing, independent of bone density. These characteristics are beyond the capability of routine DXA to identify, and as a result, DXA can be a poor prognosticator of bone health in many clinical scenarios. New clinical tools are emerging to make measurement of bone strength more accurate. This article reviews the historical timeline of bone density measurement (dual X-ray absorptiometry), expands upon the clinical observations that modified the relationship of DXA and bone strength, discusses some of the new clinical tools to predict fracture risk, and highlights the challenges DXA poses in the assessment of fracture risk in astronauts.

The effect of long-term bisphosphonate therapy on trabecular bone strength and microcrack density

PubMed Central

Jin, A.; Cobb, J.; Hansen, U.; Bhattacharya, R.; Reinhard, C.; Vo, N.; Atwood, R.; Li, J.; Karunaratne, A.; Wiles, C.

2017-01-01

Objectives Bisphosphonates (BP) are the first-line treatment for preventing fragility fractures. However, concern regarding their efficacy is growing because bisphosphonate is associated with over-suppression of remodelling and accumulation of microcracks. While dual-energy X-ray absorptiometry (DXA) scanning may show a gain in bone density, the impact of this class of drug on mechanical properties remains unclear. We therefore sought to quantify the mechanical strength of bone treated with BP (oral alendronate), and correlate data with the microarchitecture and density of microcracks in comparison with untreated controls. Methods Trabecular bone from hip fracture patients treated with BP (n = 10) was compared with naïve fractured (n = 14) and non-fractured controls (n = 6). Trabecular cores were synchrotron scanned and micro-CT scanned for microstructural analysis, including quantification of bone volume fraction, microarchitecture and microcracks. The specimens were then mechanically tested in compression. Results BP bone was 28% lower in strength than untreated hip fracture bone, and 48% lower in strength than non-fractured control bone (4.6 MPa vs 6.4 MPa vs 8.9 MPa). BP-treated bone had 24% more microcracks than naïve fractured bone and 51% more than non-fractured control (8.12/cm2 vs 6.55/cm2 vs 5.25/cm2). BP and naïve fracture bone exhibited similar trabecular microarchitecture, with significantly lower bone volume fraction and connectivity than non-fractured controls. Conclusion BP therapy had no detectable mechanical benefit in the specimens examined. Instead, its use was associated with substantially reduced bone strength. This low strength may be due to the greater accumulation of microcracks and a lack of any discernible improvement in bone volume or microarchitecture. This preliminary study suggests that the clinical impact of BP-induced microcrack accumulation may be significant. Cite this article: A. Jin, J. Cobb, U. Hansen, R. Bhattacharya, C. Reinhard, N. Vo, R. Atwood, J. Li, A. Karunaratne, C. Wiles, R. Abel. The effect of long-term bisphosphonate therapy on trabecular bone strength and microcrack density. Bone Joint Res 2017;6:602–609. DOI: 10.1302/2046-3758.610.BJR-2016-0321.R1. PMID:29066534

Development of high strength hydroxyapatite for bone tissue regeneration using nanobioactive glass composites

NASA Astrophysics Data System (ADS)

Shrivastava, Pragya; Dalai, Sridhar; Sudera, Prerna; Sivam, Santosh Param; Vijayalakshmi, S.; Sharma, Pratibha

2013-02-01

With an increasing demand of biocompatible bone substitutes for the treatment of bone diseases and bone tissue regeneration, bioactive glass composites are being tested to improvise the osteoconductive as well as osteoinductive properties. Nanobioactive glass (nBG) composites, having composition of SiO2 70 mol%, CaO 26 mol % and P2O5 4 mol% were prepared by Freeze drying method using PEG-PPG-PEG co-polymer. Polymer addition improves the mechanical strength and porosity of the scaffold of nBG. Nano Bioactive glass composites upon implantation undergo specific reactions leading to the formation of crystalline hydroxyapatite (HA). This is tested in vitro using Simulated Body Fluid (SBF). This high strength hydroxyapatite (HA) layer acts as osteoconductive in cellular environment, by acting as mineral base of bones, onto which new bone cells proliferate leading to new bone formation. Strength of the nBG composites as well as HA is in the range of cortical and cancellous bone, thus proving significant for bone tissue regeneration substitutes.

Calcium- and Phosphorus-Supplemented Diet Increases Bone Mass after Short-Term Exercise and Increases Bone Mass and Structural Strength after Long-Term Exercise in Adult Mice

PubMed Central

Friedman, Michael A.; Bailey, Alyssa M.; Rondon, Matthew J.; McNerny, Erin M.; Sahar, Nadder D.; Kohn, David H.

2016-01-01

Exercise has long-lasting benefits to bone health that may help prevent fractures by increasing bone mass, bone strength, and tissue quality. Long-term exercise of 6–12 weeks in rodents increases bone mass and bone strength. However, in growing mice, a short-term exercise program of 3 weeks can limit increases in bone mass and structural strength, compared to non-exercised controls. Short-term exercise can, however, increase tissue strength, suggesting that exercise may create competition for minerals that favors initially improving tissue-level properties over structural-level properties. It was therefore hypothesized that adding calcium and phosphorus supplements to the diet may prevent decreases in bone mass and structural strength during a short-term exercise program, while leading to greater bone mass and structural strength than exercise alone after a long-term exercise program. A short-term exercise experiment was done for 3 weeks, and a long-term exercise experiment was done for 8 weeks. For each experiment, male 16-week old C57BL/6 mice were assigned to 4 weight-matched groups–exercise and non-exercise groups fed a control or mineral-supplemented diet. Exercise consisted of treadmill running at 12 m/min, 30 min/day for 7 days/week. After 3 weeks, exercised mice fed the supplemented diet had significantly increased tibial tissue mineral content (TMC) and cross-sectional area over exercised mice fed the control diet. After 8 weeks, tibial TMC, cross-sectional area, yield force, and ultimate force were greater from the combined treatments than from either exercise or supplemented diet alone. Serum markers of bone formation (PINP) and resorption (CTX) were both decreased by exercise on day 2. In exercised mice, day 2 PINP was significantly positively correlated with day 2 serum Ca, a correlation that was weaker and negative in non-exercised mice. Increasing dietary mineral consumption during an exercise program increases bone mass after 3 weeks and increases structural strength after 8 weeks, making bones best able to resist fracture. PMID:27008546

Effect of insertion torque on bone screw pullout strength.

PubMed

Lawson, K J; Brems, J

2001-05-01

The effect of insertion torque on the holding strength of 4.5-mm ASIF/AO cortical bone screws was studied in vitro. Screw holding strength was determined using an Instron materials testing machine (Bristol, United Kingdom) on 55 lamb femora and 30 human tibiocortical bone sections. Holding strength was defined as tensile stress at pullout with rapid loading to construct failure. Different insertion torques were tested, normalizing to the thickness of cortical bone specimen engaged. These represented low, intermediate, high, and thread-damaging insertion torque. All screws inserted with thread-damaging torque and single cortex engaging screws inserted to high torque tightening moments showed diminished holding strength. This loss of strength amounted to 40%-50% less than screws inserted with less torque.

Method for fusing bone

DOEpatents

Mourant, Judith R.; Anderson, Gerhard D.; Bigio, Irving J.; Johnson, Tamara M.

1996-01-01

Method for fusing bone. The present invention is a method for joining hard tissue which includes chemically removing the mineral matrix from a thin layer of the surfaces to be joined, placing the two bones together, and heating the joint using electromagnetic radiation. The goal of the method is not to produce a full-strength weld of, for example, a cortical bone of the tibia, but rather to produce a weld of sufficient strength to hold the bone halves in registration while either external fixative devices are applied to stabilize the bone segments, or normal healing processes restore full strength to the tibia.

Quantifying Bone–relevant Activity and its Relation to Bone Strength in Girls

PubMed Central

Farr, Joshua N.; Lee, Vinson R.; Blew, Robert M.; Lohman, Timothy G.; Going, Scott B.

2011-01-01

Physical activity (PA) is critical for maximizing bone development during growth. However, there is no consensus on how well existing PA measurement tools predict bone strength. PURPOSE Compare four methods of quantifying physical activity (PA) (pedometer, 3-day physical activity recall (3DPAR), bone-specific physical activity questionnaire (BPAQ), and past year physical activity questionnaire (PYPAQ)), in young girls and evaluate their ability to predict indices of bone strength. METHODS 329 girls aged 8–13 years completed a pedometer assessment, the 3DPAR, the BPAQ, and a modified PYPAQ. Peripheral quantitative computed tomography (pQCT) was used to assess bone strength index (BSI) at metaphyseal (4% distal femur and tibia) sites and strength-strain index (SSI) at diaphyseal (femur = 20%, tibia = 66%) sites of the non-dominant leg. Correlations and hierarchical multiple regression were used to assess relationships among PA measures and indices of bone strength. RESULTS After adjustment for maturity, correlations between PA measures and indices of bone strength were positive, although low (r = 0.01–0.20). Regression models that included covariates (maturity, body mass, leg length, and ethnicity) and PA variables showed that PYPAQ score was significantly (P < 0.05) associated with BSI and SSI at all sites and explained more variance in BSI and SSI than any other PA measure. Pedometer steps were significantly (P < 0.05) associated with metaphyseal femur and tibia BSI and 3DPAR score was significantly (P < 0.05) associated with metaphyseal femur BSI. BPAQ score was not significantly (P > 0.05) associated with BSI or SSI at any sites. CONCLUSION A modified PYPAQ that accounts for the duration, frequency, and load of PA predicted indices of bone strength better than other PA measures. PMID:20631644

Protein kinase Cα (PKCα) regulates bone architecture and osteoblast activity.

PubMed

Galea, Gabriel L; Meakin, Lee B; Williams, Christopher M; Hulin-Curtis, Sarah L; Lanyon, Lance E; Poole, Alastair W; Price, Joanna S

2014-09-12

Bones' strength is achieved and maintained through adaptation to load bearing. The role of the protein kinase PKCα in this process has not been previously reported. However, we observed a phenotype in the long bones of Prkca(-/-) female but not male mice, in which bone tissue progressively invades the medullary cavity in the mid-diaphysis. This bone deposition progresses with age and is prevented by disuse but unaffected by ovariectomy. Castration of male Prkca(-/-) but not WT mice results in the formation of small amounts of intramedullary bone. Osteoblast differentiation markers and Wnt target gene expression were up-regulated in osteoblast-like cells derived from cortical bone of female Prkca(-/-) mice compared with WT. Additionally, although osteoblastic cells derived from WT proliferate following exposure to estradiol or mechanical strain, those from Prkca(-/-) mice do not. Female Prkca(-/-) mice develop splenomegaly and reduced marrow GBA1 expression reminiscent of Gaucher disease, in which PKC involvement has been suggested previously. From these data, we infer that in female mice, PKCα normally serves to prevent endosteal bone formation stimulated by load bearing. This phenotype appears to be suppressed by testicular hormones in male Prkca(-/-) mice. Within osteoblastic cells, PKCα enhances proliferation and suppresses differentiation, and this regulation involves the Wnt pathway. These findings implicate PKCα as a target gene for therapeutic approaches in low bone mass conditions. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Hyperlipidemia affects multiscale structure and strength of murine femur.

PubMed

Ascenzi, Maria-Grazia; Lutz, Andre; Du, Xia; Klimecky, Laureen; Kawas, Neal; Hourany, Talia; Jahng, Joelle; Chin, Jesse; Tintut, Yin; Nackenhors, Udo; Keyak, Joyce

2014-07-18

To improve bone strength prediction beyond limitations of assessment founded solely on the bone mineral component, we investigated the effect of hyperlipidemia, present in more than 40% of osteoporotic patients, on multiscale structure of murine bone. Our overarching purpose is to estimate bone strength accurately, to facilitate mitigating fracture morbidity and mortality in patients. Because (i) orientation of collagen type I affects, independently of degree of mineralization, cortical bone׳s micro-structural strength; and, (ii) hyperlipidemia affects collagen orientation and μCT volumetric tissue mineral density (vTMD) in murine cortical bone, we have constructed the first multiscale finite element (mFE), mouse-specific femoral model to study the effect of collagen orientation and vTMD on strength in Ldlr(-/-), a mouse model of hyperlipidemia, and its control wild type, on either high fat diet or normal diet. Each µCT scan-based mFE model included either element-specific elastic orthotropic properties calculated from collagen orientation and vTMD (collagen-density model) by experimentally validated formulation, or usual element-specific elastic isotropic material properties dependent on vTMD-only (density-only model). We found that collagen orientation, assessed by circularly polarized light and confocal microscopies, and vTMD, differed among groups and that microindentation results strongly correlate with elastic modulus of collagen-density models (r(2)=0.85, p=10(-5)). Collagen-density models yielded (1) larger strains, and therefore lower strength, in simulations of 3-point bending and physiological loading; and (2) higher correlation between mFE-predicted strength and 3-point bending experimental strength, than density-only models. This novel method supports ongoing translational research to achieve the as yet elusive goal of accurate bone strength prediction. Copyright © 2014 Elsevier Ltd. All rights reserved.

Bone strength and muscle properties in postmenopausal women with and without a recent distal radius fracture.

PubMed

Crockett, K; Arnold, C M; Farthing, J P; Chilibeck, P D; Johnston, J D; Bath, B; Baxter-Jones, A D G; Kontulainen, S A

2015-10-01

Distal radius (wrist) fracture (DRF) in women over age 50 years is an early sign of bone fragility. Women with a recent DRF compared to women without DRF demonstrated lower bone strength, muscle density, and strength, but no difference in dual-energy x-ray absorptiometry (DXA) measures, suggesting DXA alone may not be a sufficient predictor for DRF risk. The objective of this study was to investigate differences in bone and muscle properties between women with and without a recent DRF. One hundred sixty-six postmenopausal women (50-78 years) were recruited. Participants were excluded if they had taken bone-altering medications in the past 6 months or had medical conditions that severely affected daily living or the upper extremity. Seventy-seven age-matched women with a fracture in the past 6-24 months (Fx, n = 32) and without fracture (NFx, n = 45) were measured for bone and muscle properties using the nondominant (NFx) or non-fractured limb (Fx). Peripheral quantitative computed tomography (pQCT) was used to estimate bone strength in compression (BSIc) at the distal radius and tibia, bone strength in torsion (SSIp) at the shaft sites, muscle density, and area at the forearm and lower leg. Areal bone mineral density at the ultradistal forearm, spine, and femoral neck was measured by DXA. Grip strength and the 30-s chair stand test were used as estimates of upper and lower extremity muscle strength. Limb-specific between-group differences were compared using multivariate analysis of variance (MANOVA). There was a significant group difference (p < 0.05) for the forearm and lower leg, with the Fx group demonstrating 16 and 19% lower BSIc, 3 and 6% lower muscle density, and 20 and 21% lower muscle strength at the upper and lower extremities, respectively. There were no differences between groups for DXA measures. Women with recent DRF had lower pQCT-derived estimated bone strength at the distal radius and tibia and lower muscle density and strength at both extremities.

Adenovirus 36, Adiposity, and Bone Strength in Late-Adolescent Females

PubMed Central

Laing, Emma M; Tripp, Ralph A; Pollock, Norman K; Baile, Clifton A; Della-Fera, Mary Anne; Rayalam, Srujana; Tompkins, Stephen M; Keys, Deborah A; Lewis, Richard D

2017-01-01

Adenovirus 36 (Ad36) is the only adenovirus to date that has been linked with obesity in humans. Our previous studies in late-adolescent females suggest that excess weight in the form of fat mass is associated with lower cortical bone strength. The purpose of this study was to assess the relationship between Ad36-specific antibodies, adiposity, and bone strength in our sample of late-adolescent females. A cross-sectional study of 115 females aged 18 to 19 years was performed. Participants were classified according to adiposity by dual-energy X-ray absorptiometry (body fat percentage as normal-fat [<32% body fat; n=93] or high-fat [≥ 32% body fat; n=22]), and according to the presence of Ad36-specific neutralizing antibodies. Peripheral quantitative computed tomography measured bone parameters at the 4% (trabecular bone) and 20% (cortical bone) site, and muscle cross-sectional area (MCSA) at the 66% site, from the distal metaphyses of the radius and the tibia. Bone strength was determined from volumetric bone mineral density and bone geometry to calculate bone strength index (BSI; trabecular site) and polar strength–strain index (SSI; cortical site). After adjustment for MCSA and limb length, radial SSI was lower in Ad36+ versus Ad36− subjects from the high-fat group (p<0.03), but not the normal-fat group. No significant differences were observed between groups in tibial SSI or BSI. These data support an association of adiposity and cortical bone strength at the radius with the presence of neutralizing antibodies to Ad36 in late-adolescent females. PMID:23296755

Epigallocatechin Gallate-Modified Gelatin Sponges Treated by Vacuum Heating as a Novel Scaffold for Bone Tissue Engineering.

PubMed

Honda, Yoshitomo; Takeda, Yoshihiro; Li, Peiqi; Huang, Anqi; Sasayama, Satoshi; Hara, Eiki; Uemura, Naoya; Ueda, Mamoru; Hashimoto, Masanori; Arita, Kenji; Matsumoto, Naoyuki; Hashimoto, Yoshiya; Baba, Shunsuke; Tanaka, Tomonari

2018-04-11

Chemical modification of gelatin using epigallocatechin gallate (EGCG) promotes bone formation in vivo. However, further improvements are required to increase the mechanical strength and bone-forming ability of fabricated EGCG-modified gelatin sponges (EGCG-GS) for practical applications in regenerative therapy. In the present study, we investigated whether vacuum heating-induced dehydrothermal cross-linking of EGCG-GS enhances bone formation in critical-sized rat calvarial defects. The bone-forming ability of vacuum-heated EGCG-GS (vhEGCG-GS) and other sponges was evaluated by micro-computed tomography and histological staining. The degradation of sponges was assessed using protein assays, and cell morphology and proliferation were verified by scanning electron microscopy and immunostaining using osteoblastic UMR106 cells in vitro. Four weeks after the implantation of sponges, greater bone formation was detected for vhEGCG-GS than for EGCG-GS or vacuum-heated gelatin sponges (dehydrothermal cross-linked sponges without EGCG). In vitro experiments revealed that the relatively low degradability of vhEGCG-GS supports cell attachment, proliferation, and cell-cell communication on the matrix. These findings suggest that vacuum heating enhanced the bone forming ability of EGCG-GS, possibly via the dehydrothermal cross-linking of EGCG-GS, which provides a scaffold for cells, and by maintaining the pharmacological effect of EGCG.

Does a novel school-based physical activity model benefit femoral neck bone strength in pre- and early pubertal children?

PubMed

Macdonald, H M; Kontulainen, S A; Petit, M A; Beck, T J; Khan, K M; McKay, H A

2008-10-01

The effects of physical activity on bone strength acquisition during growth are not well understood. In our cluster randomized trial, we found that participation in a novel school-based physical activity program enhanced bone strength acquisition and bone mass accrual by 2-5% at the femoral neck in girls; however, these benefits depended on teacher compliance with intervention delivery. Our intervention also enhanced bone mass accrual by 2-4% at the lumbar spine and total body in boys. We investigated the effects of a novel school-based physical activity program on femoral neck (FN) bone strength and mass in children aged 9-11 yrs. We used hip structure analysis to compare 16-month changes in FN bone strength, geometry and bone mineral content (BMC) between 293 children who participated in Action Schools! BC (AS! BC) and 117 controls. We assessed proximal femur (PF), lumbar spine (LS) and total body (TB) BMC using DXA. We compared change in bone outcomes between groups using linear regression accounting for the random school effect and select covariates. Change in FN strength (section modulus, Z), cross-sectional area (CSA), subperiosteal width and BMC was similar between control and intervention boys, but intervention boys had greater gains in BMC at the LS (+2.7%, p = 0.05) and TB (+1.7%, p = 0.03) than controls. For girls, change in FN-Z tended to be greater (+3.5%, p = 0.1) for intervention girls than controls. The difference in change increased to 5.4% (p = 0.05) in a per-protocol analysis that included girls whose teachers reported 80% compliance. AS! BC benefits bone strength and mass in school-aged children; however, our findings highlight the importance of accounting for teacher compliance in classroom-based physical activity interventions.

Brief Report: HIV Infection Is Associated With Worse Bone Material Properties, Independently of Bone Mineral Density.

PubMed

Güerri-Fernández, Robert; Molina, Daniel; Villar-García, Judit; Prieto-Alhambra, Daniel; Mellibovsky, Leonardo; Nogués, Xavier; González-Mena, Alicia; Guelar, Ana; Trenchs-Rodríguez, Marta; Herrera-Fernández, Sabina; Horcajada, Juan Pablo; Díez-Pérez, Adolfo; Knobel, Hernando

2016-07-01

Low bone mineral density (BMD) in HIV-infected individuals has been documented in an increasing number of studies. However, it is not clear whether it is the infection itself or the treatment that causes bone impairment. Microindentation measures bone material strength (Bone Material Strength index) directly. We recruited 85 patients, 50 infected with HIV and 35 controls. Median Bone Material Strength index was 84.5 (interquartile range 83-87) in HIV-infected patients and 90 (88.5-93) in controls (P < 0.001). No significant differences in BMD between cases and controls at any of the sites examined (total hip, femoral neck, and lumbar spine). HIV infection is associated with bone damage, independently of BMD.

Influence of Exercise and Training on Critical Stages of Bone Growth and Development.

PubMed

Klentrou, Panagiota

2016-05-01

Although osteoporosis is considered a geriatric disease, factors affecting bone strength are most influential during child growth and development. This article reviews what is known and still unclear in terms of bone growth, development and adaptation relative to physical activity before and during puberty. Bone is responsive to certain exercise protocols early in puberty and less so in postpubertal years, where bone strength, rather than bone mass, being the outcome of interest. Mechanical loading and high impact exercise promote bone strength. Intense training before and during puberty, however, may negatively affect bone development. Future research should focus on increasing our mechanistic understanding of the manner by which diverse physical stressors alter the integrity of bone. Longitudinal studies that examine the extent to which muscle and bone are comodulated by growth in children are also recommended.

Using cell and organ culture models to analyze responses of bone cells to mechanical stimulation.

PubMed

Pitsillides, Andrew A; Rawlinson, Simon C F

2012-01-01

Bone cells of the osteoblastic lineage are responsive to the local mechanical environment. Through integration of a number of possible loading-induced regulatory stimuli, osteocyte, osteoblast, and osteoclast behaviour is organized to fashion a skeletal element of sufficient strength and toughness to resist fracture and crack propagation. Early pre-osteogenic responses had been determined in vivo and this led to the development of bone organ culture models to elucidate other pre-osteogenic responses where osteocytes and osteoblasts retain the natural orientation, connections and attachments to their native extracellular matrix. The application of physiological mechanical loads to bone in these organ culture models generates the regulatory stimuli. As a consequence, these experiments can be used to illustrate the distinctive mechanisms by which osteocytes and osteoblasts respond to mechanical loads and also differences in these responses, suggesting co-ordinated and cooperatively between cell populations. Organ explant cultures are awkward to maintain, and have a limited life, but length of culture times are improving. Monolayer cultures are much easier to maintain and permit the application of a particular mechanical stimulation to be studied in isolation; mainly direct mechanical strain or fluid shear strains. These allow for the response of a single cell type to the applied mechanical stimulation to be monitored precisely.The techniques that can be used to apply mechanical strain to bone and bone cells have not advanced greatly since the first edition. The output from such experiments has, however, increased substantially and their importance is now more broadly accepted. This suggests a growing use of these approaches and an increasing awareness of the importance of the mechanical environment in controlling normal bone cell behaviour. We expand the text to include additions and modifications made to the straining apparatus and update the research cited to support this growing role of cell and organ culture models to analyze responses of bone cells to mechanical stimulation.

Bone microarchitecture and estimated bone strength in men with active acromegaly.

PubMed

Silva, Paula P B; Amlashi, Fatemeh G; Yu, Elaine W; Pulaski-Liebert, Karen J; Gerweck, Anu V; Fazeli, Pouneh K; Lawson, Elizabeth; Nachtigall, Lisa B; Biller, Beverly M K; Miller, Karen K; Klibanski, Anne; Bouxsein, Mary; Tritos, Nicholas A

2017-11-01

Both acromegaly and adult growth hormone deficiency (GHD) are associated with increased fracture risk. Sufficient data are lacking regarding cortical bone microarchitecture and bone strength, as assessed by microfinite element analysis (µFEA). To elucidate both cortical and trabecular bone microarchitecture and estimated bone strength in men with active acromegaly or GHD compared to healthy controls. Cross-sectional study at a clinical research center, including 48 men (16 with acromegaly, 16 with GHD and 16 healthy controls). Areal bone mineral density (aBMD), cortical and trabecular bone microarchitecture and estimated bone strength (µFEA) at the radius and tibia. aBMD was not different between the 3 groups at any skeletal site. At the radius, patients with acromegaly had greater cortical area ( P  < 0.0001), cortical thickness ( P  = 0.0038), cortical pore volume ( P  < 0.0001) and cortical porosity ( P  = 0.0008), but lower trabecular bone density ( P  = 0.0010) compared to controls. At the tibia, patients with acromegaly had lower trabecular bone density ( P  = 0.0082), but no differences in cortical bone microstructure. Compressive strength and failure load did not significantly differ between groups. These findings persisted after excluding patients with hypogonadism. Bone microarchitecture was not deficient in patients with GHD. Both cortical and trabecular microarchitecture are altered in men with acromegaly. Our data indicate that GH excess is associated with distinct effects in cortical vs trabecular bone compartments. Our observations also affirm the limitations of aBMD testing in the evaluation of patients with acromegaly. © 2017 European Society of Endocrinology.

The effects of cortical bone thickness and trabecular bone strength on noninvasive measures of the implant primary stability using synthetic bone models.

PubMed

Hsu, Jui-Ting; Fuh, Lih-Jyh; Tu, Ming-Gene; Li, Yu-Fen; Chen, Kuan-Ting; Huang, Heng-Li

2013-04-01

This study investigated how the primary stability of a dental implant as measured by the insertion torque value (ITV), Periotest value (PTV), and implant stability quotient (ISQ) is affected by varying thicknesses of cortical bone and strengths of trabecular bone using synthetic bone models. Four synthetic cortical shells (with thicknesses of 0, 1, 2, and 3 mm) were attached to four cellular rigid polyurethane foams (with elastic moduli of 137, 47.5, 23, and 12.4 MPa) and one open-cell rigid polyurethane foam which mimic the osteoporotic bone (with an elastic modulus 6.5 MPa), to represent the jawbones with various cortical bone thicknesses and strengths of trabecular bone. A total of 60 bone specimens accompanied with implants was examined by a torque meter, Osstell resonance frequency analyzer, and Periotest electronic device. All data were statistically analyzed by two-way analysis of variance. In addition, second-order nonlinear regression was utilized to assess the correlations of the primary implant stability with the four cortex thicknesses and five strengths of trabecular bone. ITV, ISQ, and PTV differed significantly (p < .05) and were strongly correlated with the thickness of cortical bone (R(2) > 0.9) and the elastic modulus of trabecular bone (R(2) = 0.74-0.99). The initial stability at the time of implant placement is influenced by both the cortical bone thickness and the strength of trabecular bone; however, these factors are mostly nonlinearly correlated with ITV, PTV, and ISQ. Using ITV and PTV seems more suitable for identifying the primary implant stability in osteoporotic bone with a thin cortex. © 2011 Wiley Periodicals, Inc.

Predicting Bone Mechanical State During Recovery After Long-Duration Skeletal Unloading Using QCT and Finite Element Modeling

NASA Technical Reports Server (NTRS)

Chang, Katarina L.; Pennline, James A.

2013-01-01

During long-duration missions at the International Space Station, astronauts experience weightlessness leading to skeletal unloading. Unloading causes a lack of a mechanical stimulus that triggers bone cellular units to remove mass from the skeleton. A mathematical system of the cellular dynamics predicts theoretical changes to volume fractions and ash fraction in response to temporal variations in skeletal loading. No current model uses image technology to gather information about a skeletal site s initial properties to calculate bone remodeling changes and then to compare predicted bone strengths with the initial strength. The goal of this study is to use quantitative computed tomography (QCT) in conjunction with a computational model of the bone remodeling process to establish initial bone properties to predict changes in bone mechanics during bone loss and recovery with finite element (FE) modeling. Input parameters for the remodeling model include bone volume fraction and ash fraction, which are both computed from the QCT images. A non-destructive approach to measure ash fraction is also derived. Voxel-based finite element models (FEM) created from QCTs provide initial evaluation of bone strength. Bone volume fraction and ash fraction outputs from the computational model predict changes to the elastic modulus of bone via a two-parameter equation. The modulus captures the effect of bone remodeling and functions as the key to evaluate of changes in strength. Application of this time-dependent modulus to FEMs and composite beam theory enables an assessment of bone mechanics during recovery. Prediction of bone strength is not only important for astronauts, but is also pertinent to millions of patients with osteoporosis and low bone density.

Method for fusing bone

DOEpatents

Mourant, J.R.; Anderson, G.D.; Bigio, I.J.; Johnson, T.M.

1996-03-12

The present invention is a method for joining hard tissue which includes chemically removing the mineral matrix from a thin layer of the surfaces to be joined, placing the two bones together, and heating the joint using electromagnetic radiation. The goal of the method is not to produce a full-strength weld of, for example, a cortical bone of the tibia, but rather to produce a weld of sufficient strength to hold the bone halves in registration while either external fixative devices are applied to stabilize the bone segments, or normal healing processes restore full strength to the tibia.

Inflammatory bowel disease causes reversible suppression of osteoblast and chondrocyte function in mice.

PubMed

Harris, Laura; Senagore, Patricia; Young, Vincent B; McCabe, Laura R

2009-05-01

Decreased bone density and stature can occur in pediatric patients with inflammatory bowel disease (IBD). Little is known about how IBD broadly impacts the skeleton. To evaluate the influence of an acute episode of IBD on growing bone, 4-wk-old mice were administered 5% dextran sodium sulfate (DSS) for 5 days to induce colitis and their recovery was monitored. During active disease and early recovery, trabecular bone mineral density, bone volume, and thickness were decreased. Cortical bone thickness, outer perimeter, and density were also decreased, whereas inner perimeter and marrow area were increased. These changes appear to maintain bone strength since measures of moments of inertia were similar between DSS-treated and control mice. Histological (static and dynamic), serum, and RNA analyses indicate that a decrease in osteoblast maturation and function account for changes in bone density. Unlike some conditions of bone loss, marrow adiposity did not increase. Similar to reports in humans, bone length decreased and correlated with decreases in growth plate thickness and chondrocyte marker expression. During disease recovery, mice experienced a growth spurt that led to their achieving final body weights and bone length, density, and gene expression similar to healthy controls. Increased TNF-alpha and decreased IGF-I serum levels were observed with active disease and returned to normal with recovery. Changes in serum TNF-alpha (increased) and IGF-I (decreased) paralleled changes in bone parameters and returned to normal values with recovery, suggesting a potential role in the skeletal response.

Non-elite gymnastics participation is associated with greater bone strength, muscle size, and function in pre- and early pubertal girls.

PubMed

Burt, L A; Naughton, G A; Greene, D A; Courteix, D; Ducher, G

2012-04-01

Recent reports indicate an increase in forearm fractures in children. Bone geometric properties are an important determinant of bone strength and therefore fracture risk. Participation in non-elite gymnastics appears to contribute to improving young girls' musculoskeletal health, more specifically in the upper body. The primary aim of this study was to determine the association between non-elite gymnastics participation and upper limb bone mass, geometry, and strength in addition to muscle size and function in young girls. Eighty-eight pre- and early pubertal girls (30 high-training gymnasts [HGYM, 6-16 hr/ wk], 29 low-training gymnasts [LGYM, 1-5 h r/wk] and 29 non-gymnasts [NONGYM]), aged 6-11 years were recruited. Upper limb lean mass, BMD and BMC were derived from a whole body DXA scan. Forearm volumetric BMD, bone geometry, estimated strength, and muscle CSA were determined using peripheral QCT. Upper body muscle function was investigated with muscle strength, explosive power, and muscle endurance tasks. HGYM showed greater forearm bone strength compared with NGYM, as well as greater arm lean mass, BMC, and muscle function (+5% to +103%, p < 0.05). LGYM displayed greater arm lean mass, BMC, muscle power, and endurance than NGYM (+4% to +46%, p < 0.05); however, the difference in bone strength did not reach significance. Estimated fracture risk at the distal radius, which accounted for body weight, was lower in both groups of gymnasts. Compared with NONGYM, HGYM tended to show larger skeletal differences than LGYM; yet, the two groups of gymnasts only differed for arm lean mass and muscle CSA. Non-elite gymnastics participation was associated with musculoskeletal benefits in upper limb bone geometry, strength and muscle function. Differences between the two gymnastic groups emerged for arm lean mass and muscle CSA, but not for bone strength.

Relationship of total body fat mass to weight-bearing bone volumetric density, geometry, and strength in young girls

PubMed Central

Farr, Joshua N.; Chen, Zhao; Lisse, Jeffrey R.; Lohman, Timothy G.; Going, Scott B.

2010-01-01

Understanding the influence of total body fat mass (TBFM) on bone during the peri-pubertal years is critical for the development of future interventions aimed at improving bone strength and reducing fracture risk. Thus, we evaluated the relationship of TBFM to volumetric bone mineral density (vBMD), geometry, and strength at metaphyseal and diaphyseal sites of the femur and tibia of young girls. Data from 396 girls aged 8–13 years from the “Jump-In: Building Better Bones” study were analyzed. Bone parameters were assessed using peripheral quantitative computed tomography (pQCT) at the 4% and 20% distal femur and 4% and 66% distal tibia of the non-dominant leg. Bone parameters at the 4% sites included trabecular vBMD, periosteal circumference, and bone strength index (BSI), while at the 20% femur and 66% tibia, parameters included cortical vBMD, periosteal circumference, and strength-strain index (SSI). Multiple linear regression analyses were used to assess associations between bone parameters and TBFM, controlling for muscle cross-sectional area (MCSA). Regression analyses were then repeated with maturity, bone length, physical activity, and ethnicity as additional covariates. Analysis of covariance (ANCOVA) was used to compare bone parameters among tertiles of TBFM. In regression models with TBFM and MCSA, associations between TBFM and bone parameters at all sites were not significant. TBFM explained very little variance in all bone parameters (0.2–2.3%). In contrast, MCSA was strongly related (p < 0.001) to all bone parameters, except cortical vBMD. The addition of maturity, bone length, physical activity, and ethnicity did not alter the relationship between TBFM and bone parameters. With bone parameters expressed relative to total body mass, ANCOVA showed that all outcomes were significantly (p < 0.001) greater in the lowest compared to the middle and highest tertiles of TBFM. Although TBFM is correlated with femur and tibia vBMD, periosteal circumference, and strength in young girls, this relationship is significantly attenuated after adjustment for MCSA. Nevertheless, girls with higher TBFM relative to body mass have markedly diminished vBMD, geometry, and bone strength at metaphyseal and diaphyseal sites of the femur and tibia. PMID:20060079

Simulated weightlessness and synbiotic diet effects on rat bone mechanical strength

NASA Astrophysics Data System (ADS)

Sarper, Hüseyin; Blanton, Cynthia; DePalma, Jude; Melnykov, Igor V.; Gabaldón, Annette M.

2014-10-01

This paper reports results on exposure to simulated weightlessness that leads to a rapid decrease in bone mineral density known as spaceflight osteopenia by evaluating the effectiveness of dietary supplementation with synbiotics to counteract the effects of skeletal unloading. Forty adult male rats were studied under four different conditions in a 2 × 2 factorial design with main effects of diet (synbiotic and control) and weight condition (unloaded and control). Hindlimb unloading was performed at all times for 14 days followed by 14 days of recovery (reambulation). The synbiotic diet contained probiotic strains Lactobacillus acidophilus and Lactococcus lactis lactis and prebiotic fructooligosaccharide. This paper also reports on the development of a desktop three-point bending device to measure the mechanical strength of bones from rats subjected to simulated weightlessness. The importance of quantifying bone resistance to breakage is critical when examining the effectiveness of interventions against osteopenia resulting from skeletal unloading, such as astronauts experience, disuse or disease. Mechanical strength indices provide information beyond measures of bone density and microarchitecture that enhance the overall assessment of a treatment's potency. In this study we used a newly constructed three-point bending device to measure the mechanical strength of femur and tibia bones from hindlimb-unloaded rats fed an experimental synbiotic diet enriched with probiotics and fermentable fiber. Two calculated outputs for each sample were Young's modulus of elasticity and fracture stress. Bone major elements (calcium, magnesium, and phosphorous) were quantified using ICP-MS analysis. Hindlimb unloading was associated with a significant loss of strength in the femur, and with significant reductions in major bone elements. The synbiotic diet did not protect against these unloading effects. Tibia strength and major elements were not reduced by hindlimb unloading, as was the case for femur, but tibia bone strength was negatively affected by the synbiotic diet. Thus, unexpectedly, the synbiotic diet was associated with null or detrimental effects on bone strength.

Preservation of bone structure and function by Lithothamnion sp. – derived minerals

PubMed Central

Aslam, Muhammad Nadeem; Bergin, Ingrid; Jepsen, Karl; Kreider, Jaclynn M.; Graf, Kristin H.; Naik, Madhav; Goldstein, Steven A.; Varani, James

2013-01-01

Progressive bone mineral loss and increasing bone fragility are hallmarks of osteoporosis. A combination of minerals isolated from the red marine algae, Lithothamnion sp. was examined for ability to inhibit bone mineral loss in female mice maintained on either a standard rodent chow (control) diet or a high-fat western diet (HFWD) for 5-, 12- and 18-months. At each time-point, femora were subjected to μ-CT analysis and biomechanical testing. A subset of caudal vertebrae was also analyzed. Following this, individual elements were assessed in bones. Serum levels of the 5b isoform of tartrate-resistant acid phosphatase (TRAP) and procollagen type I propeptide (P1NP) were also measured. Trabecular bone loss occurred in both diets (evident as early as 5-months). Cortical bone increased through month-5 and then declined. Cortical bone loss was primarily in mice on the HFWD. Inclusion of the minerals in the diet reduced bone mineral loss in both diets and improved bone strength. Bone mineral density (BMD) was also enhanced by these minerals. Of several cationic minerals known to be important to bone health, only strontium was significantly increased in bone tissue from animals fed the mineral diets, but the increase was large (5–10 fold). Serum levels of TRAP were consistently higher in mice receiving the minerals but levels of P1NP were not. These data suggest that trace minerals derived from marine red algae may be used to prevent progressive bone mineral loss in conjunction with calcium. Mineral supplementation could find use as part of an osteoporosis - prevention strategy. PMID:24096551

Preservation of bone structure and function by Lithothamnion sp. derived minerals.

PubMed

Aslam, Muhammad Nadeem; Bergin, Ingrid; Jepsen, Karl; Kreider, Jaclynn M; Graf, Kristin H; Naik, Madhav; Goldstein, Steven A; Varani, James

2013-12-01

Progressive bone mineral loss and increasing bone fragility are hallmarks of osteoporosis. A combination of minerals isolated from the red marine algae, Lithothamnion sp. was examined for ability to inhibit bone mineral loss in female mice maintained on either a standard rodent chow (control) diet or a high-fat western diet (HFWD) for 5, 12, and 18 months. At each time point, femora were subjected to μ-CT analysis and biomechanical testing. A subset of caudal vertebrae was also analyzed. Following this, individual elements were assessed in bones. Serum levels of the 5b isoform of tartrate-resistant acid phosphatase (TRAP) and procollagen type I propeptide (P1NP) were also measured. Trabecular bone loss occurred in both diets (evident as early as 5 months). Cortical bone increased through month 5 and then declined. Cortical bone loss was primarily in mice on the HFWD. Inclusion of the minerals in the diet reduced bone mineral loss in both diets and improved bone strength. Bone mineral density was also enhanced by these minerals. Of several cationic minerals known to be important to bone health, only strontium was significantly increased in bone tissue from animals fed the mineral diets, but the increase was large (5-10 fold). Serum levels of TRAP were consistently higher in mice receiving the minerals, but levels of P1NP were not. These data suggest that trace minerals derived from marine red algae may be used to prevent progressive bone mineral loss in conjunction with calcium. Mineral supplementation could find use as part of an osteoporosis-prevention strategy.

Women with previous fragility fractures can be classified based on bone microarchitecture and finite element analysis measured with HR-pQCT.

PubMed

Nishiyama, K K; Macdonald, H M; Hanley, D A; Boyd, S K

2013-05-01

High-resolution peripheral quantitative computed tomography (HR-pQCT) measurements of distal radius and tibia bone microarchitecture and finite element (FE) estimates of bone strength performed well at classifying postmenopausal women with and without previous fracture. The HR-pQCT measurements outperformed dual energy x-ray absorptiometry (DXA) at classifying forearm fractures and fractures at other skeletal sites. Areal bone mineral density (aBMD) is the primary measurement used to assess osteoporosis and fracture risk; however, it does not take into account bone microarchitecture, which also contributes to bone strength. Thus, our objective was to determine if bone microarchitecture measured with HR-pQCT and FE estimates of bone strength could classify women with and without low-trauma fractures. We used HR-pQCT to assess bone microarchitecture at the distal radius and tibia in 44 postmenopausal women with a history of low-trauma fracture and 88 age-matched controls from the Calgary cohort of the Canadian Multicentre Osteoporosis Study (CaMos) study. We estimated bone strength using FE analysis and simulated distal radius aBMD from the HR-pQCT scans. Femoral neck (FN) and lumbar spine (LS) aBMD were measured with DXA. We used support vector machines (SVM) and a tenfold cross-validation to classify the fracture cases and controls and to determine accuracy. The combination of HR-pQCT measures of microarchitecture and FE estimates of bone strength had the highest area under the receiver operating characteristic (ROC) curve of 0.82 when classifying forearm fractures compared to an area under the curve (AUC) of 0.71 from DXA-derived aBMD of the forearm and 0.63 from FN and spine DXA. For all fracture types, FE estimates of bone strength at the forearm alone resulted in an AUC of 0.69. Models based on HR-pQCT measurements of bone microarchitecture and estimates of bone strength performed better than DXA-derived aBMD at classifying women with and without prior fracture. In future, these models may improve prediction of individuals at risk of low-trauma fracture.

Bone strength and athletic ability in hominids: Ardipithecus ramidus to Homo sapiens

NASA Astrophysics Data System (ADS)

Lee, S. A.

2013-03-01

The ability of the femur to resist bending stresses is determined by its midlength cross-sectional geometry, its length and the elastic properties of the mineral part of the bone. The animal's athletic ability, determined by a ``bone strength index,'' is limited by this femoral bending strength in relation to the loads on the femur. This analysis is applied to the fossil record for Homo sapiens, Homo neanderthalensis, Homo erectus, Homo habilis, Australopithecus afarensis and Ardipithecus ramidus. Evidence that the femoral bone strength index of modern Homo sapiens has weakened over the last 50,000 years is found.

Mechanical response tissue analyzer for estimating bone strength

NASA Technical Reports Server (NTRS)

Arnaud, Sara B.; Steele, Charles; Mauriello, Anthony

1991-01-01

One of the major concerns for extended space flight is weakness of the long bones of the legs, composed primarily of cortical bone, that functions to provide mechanical support. The strength of cortical bone is due to its complex structure, described simplistically as cylinders of parallel osteons composed of layers of mineralized collagen. The reduced mechanical stresses during space flight or immobilization of bone on Earth reduces the mineral content, and changes the components of its matrix and structure so that its strength is reduced. Currently, the established clinical measures of bone strength are indirect. The measures are based on determinations of mineral density by means of radiography, photon absorptiometry, and quantitative computer tomography. While the mineral content of bone is essential to its strength, there is growing awareness of the limitations of the measurement as the sole predictor of fracture risk in metabolic bone diseases, especially limitations of the measurement as the sole predictor of fracture risk in metabolic bone diseases, especially osteoporosis. Other experimental methods in clinical trials that more directly evaluate the physical properties of bone, and do not require exposure to radiation, include ultrasound, acoustic emission, and low-frequency mechanical vibration. The last method can be considered a direct measure of the functional capacity of a long bone since it quantifies the mechanical response to a stimulus delivered directly to the bone. A low frequency vibration induces a response (impedance) curve with a minimum at the resonant frequency, that a few investigators use for the evaluation of the bone. An alternative approach, the method under consideration, is to use the response curve as the basis for determination of the bone bending stiffness EI (E is the intrinsic material property and I is the cross-sectional moment of inertia) and mass, fundamental mechanical properties of bone.

Theoretical Bounds for the Influence of Tissue-Level Ductility on the Apparent-Level Strength of Human Trabecular Bone

PubMed Central

Nawathe, Shashank; Juillard, Frédéric; Keaveny, Tony M.

2015-01-01

The role of tissue-level post-yield behavior on the apparent-level strength of trabecular bone is a potentially important aspect of bone quality. To gain insight into this issue, we compared the apparent-level strength of trabecular bone for the hypothetical cases of fully brittle versus fully ductile failure behavior of the trabecular tissue. Twenty human cadaver trabecular bone specimens (5 mm cube; BV/TV = 6–36%) were scanned with micro-CT to create 3D finite element models (22-micron element size). For each model, apparent-level strength was computed assuming either fully brittle (fracture with no tissue ductility) or fully ductile (yield with no tissue fracture) tissue-level behaviors. We found that the apparent-level ultimate strength for the brittle behavior was only about half the value of the apparent-level 0.2%-offset yield strength for the ductile behavior, and the ratio of these brittle to ductile strengths was almost constant (mean ± SD = 0.56 ± 0.02; n=20; R2 = 0.99 between the two measures). As a result of this small variation, although the ratio of brittle to ductile strengths was positively correlated with the bone volume fraction (R2=0.44, p=0.01) and structure model index (SMI, R2=0.58, p<0.01), these effects were small. Mechanistically, the fully ductile behavior resulted in a much higher apparent-level strength because in this case about 16-fold more tissue was required to fail than for the fully brittle behavior; also, there was more tensile- than compressive-mode of failure at the tissue level for the fully brittle behavior. We conclude that, in theory, the apparent-level strength behavior of human trabecular bone can vary appreciably depending on whether the tissue fails in a fully ductile versus fully brittle manner, and this effect is largely constant despite appreciable variations in bone volume fraction and microarchitecture. PMID:23497799

Hypoalgesic and motor effects of kaltenborn mobilization on elderly patients with secondary thumb carpometacarpal osteoarthritis: a randomized controlled trial.

PubMed

Villafañe, Jorge H; Silva, Guillermo B; Diaz-Parreño, Santiago A; Fernandez-Carnero, Josue

2011-10-01

This study evaluated the effects of Kaltenborn manual therapy on sensory and motor function in elderly patients with secondary carpometacarpal osteoarthritis (CMC OA). Twenty-nine female patients with secondary CMC OA (70-90 years old) were randomized into Kaltenborn manual therapy and sham groups. This study was designed as a double-blind, randomized controlled trial (RCT). Therapy consisted of Kaltenborn mobilization of posterior-anterior gliding with distraction in grade 3 of the carpometacarpal (CMC) joint of the dominant hand during 6 sessions over 2 weeks. Pain was measured by algometry, as the pressure pain threshold (PPT) at the CMC joint and tubercle of the scaphoid bone. The tip and tripod pinch strength was also measured. Grip strength was measured by a grip dynamometer. Measurements were taken before treatment and after 1 week (first follow-up [FU]) and 2 weeks (second FU). All values in the sham group remained unchanged during the treatment period. In the treated group, the PPT in the CMC joint was 2.98 ± 0.30 kg/cm(2), which increased after treatment to 4.07 ± 0.53, and was maintained at the same level during the first FU (3.46 ± 0.31) and second FU (3.84 ± 0.36). Similarly, the PPT in the scaphoid bone was 3.61 ± 0.29 kg/cm(2), which increased after treatment to 4.87 ± 0.37, and was maintained at the same level during the first FU (4.44 ± 0.43) and second FU (4.22 ± 0.32). In contrast, we found no differences in the tip, tripod pinch, and grip strength measurements between the treatment and sham groups. This study showed that Kaltenborn manual therapy decreased pain in the CMC joint and scaphoid bone areas of elderly female patients; however, it did not confer an increase in motor function in patients with CMC OA. Copyright © 2011 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

[Toward an anthropometric diagnosis of osteopenia and a biochemical diagnosis of osteoporoses].

PubMed

Cointry, Gustavo R; Capozza, Ricardo F; Ferretti, Jose L; Frost, Harold M

2003-01-01

The current (metabolic) conception of bone-weakening diseases regards bone strength as determined by a systemically-controlled "mineralized mass" which grows until it reaches a peak and then is lost at individually-specific rates. This concept disregards bone biomechanics. Skeletons are structures, it reaches of which depends on the stiffness and the spatial distribution rather than the volume of the calcified material. Rather than allowing a systemic regulation of their "mass" as a way to optimize their strength, bones autocontrol their stiffness by orienting bone formation and destruction as locally determined by the directional sensing, by osteocytes, of the strains caused by mechanical usage (gravity, muscle contractions). Bone mass and strength are just side products of that control. Endocrine-metabolic systems modulate non-directionally the work of bone cells as required for achieving a mineral equilibrium, despite the biomechanical controls, and can determine osteopenias and osteoporoses. Osteoporoses are not "intense osteopenias" (as per the current WHO's conception) but "osteopenic bone fragilities" (as recently stated by the NIH). The diagnosis of osteopenia is an anthropometric problem that can be solved densitometrically; but that of bone fragility is a biomechanical matter that requires evaluation of bone material's stiffness and distribution by other means ("resistometry"). For therapeutic purposes, osteopenias and osteoporoses should be also evaluated according to the relationship between bone mass or strength and muscle mass or strength in order to distinguish between "mechanical" (disuse) and "metabolic" etiologies (intrinsic bone lesion, or systemic disequilibrium), in which the bone/muscle proportionality tends to remain normal or to deteriorate, respectively.

Bone's mechanostat: a 2003 update.

PubMed

Frost, Harold M

2003-12-01

The still-evolving mechanostat hypothesis for bones inserts tissue-level realities into the former knowledge gap between bone's organ-level and cell-level realities. It concerns load-bearing bones in postnatal free-living bony vertebrates, physiologic bone loading, and how bones adapt their strength to the mechanical loads on them. Voluntary mechanical usage determines most of the postnatal strength of healthy bones in ways that minimize nontraumatic fractures and create a bone-strength safety factor. The mechanostat hypothesis predicts 32 things that occur, including the gross anatomical bone abnormalities in osteogenesis imperfecta; it distinguishes postnatal situations from baseline conditions at birth; it distinguishes bones that carry typical voluntary loads from bones that have other chief functions; and it distinguishes traumatic from nontraumatic fractures. It provides functional definitions of mechanical bone competence, bone quality, osteopenias, and osteoporoses. It includes permissive hormonal and other effects on bones, a marrow mediator mechanism, some limitations of clinical densitometry, a cause of bone "mass" plateaus during treatment, an "adaptational lag" in some children, and some vibration effects on bones. The mechanostat hypothesis may have analogs in nonosseous skeletal organs as well. Copyright 2003 Wiley-Liss, Inc.

Bone architecture and strength in the growing skeleton: the role of sedentary time.

PubMed

Gabel, Leigh; McKay, Heather A; Nettlefold, Lindsay; Race, Douglas; Macdonald, Heather M

2015-02-01

Today's youths spend close to 60% of their waking hours in sedentary activities; however, we know little about the potentially deleterious effects of sedentary time on bone health during this key period of growth and development. Thus, our objective was to determine whether sedentary time is associated with bone architecture, mineral density, and strength in children, adolescents, and young adults. We used high-resolution peripheral quantitative computed tomography (Scanco Medical) to measure bone architecture (trabecular and cortical microstructure and bone macrostructure) and cortical and total bone mineral density (BMD) at the distal tibia (8% site) in 154 males and 174 females (9-20 yr) who were participants in the University of British Columbia Healthy Bones III study. We applied finite element analysis to high-resolution peripheral quantitative computed tomography scans to estimate bone strength. We assessed self-reported screen time in all participants using a questionnaire and sedentary time (volume and patterns) in a subsample of participants with valid accelerometry data (89 males and 117 females; ActiGraph GT1M). We fit sex-specific univariate multivariable regression models, controlling for muscle cross-sectional area, limb length, maturity, ethnicity, dietary calcium, and physical activity. We did not observe independent effect of screen time on bone architecture, BMD, or strength in either sex (P > 0.05). Likewise, when adjusted for muscle cross-sectional area, limb length, maturity, ethnicity, dietary calcium, and physical activity, accelerometry-derived volume of sedentary time and breaks in bouts of sedentary time were not a determinant of bone architecture, BMD, or strength in either sex (P > 0.05). Further study is warranted to determine whether the lack of association between sedentary time and bone architecture, BMD, and strength at the distal tibia is also present at other skeletal sites.

Osteoporosis: Are we measuring what we intend to measure? In search of the ideal bone strength study

NASA Astrophysics Data System (ADS)

de Riese, Cornelia

2006-02-01

In 1991 the World Health Organization (WHO) defined osteoporosis as a "loss of bone mass and micro architectural deterioration of the skeleton leading to increased risk of fracture." 1,2 Since microarchitecture can not be measured directly, a panel of the WHO recommended that the diagnosis be made according to a quantifiable surrogate marker, calcium mineral, in bone. Subsequently in 1994, the definition focused on the actual bone "density," giving densitometric technology a central place in establishing the diagnosis of osteoporosis. 3,4 But soon it became obvious that there was only limited correlation between bone mineral density (BMD) and actual occurrence of fractures and that decreases in bone mass account for only about 50% of the deterioration of bone strength with aging. In other words only about 60% of bone strength is related to BMD. 5 Recent developments in bone research have shown that bone mineral density in itself is not sufficient to accurately predict fracture risk. Bone is composed of inorganic calcium apatite crystals that mineralize an organic type I collagen matrix. The degree of mineralization, the properties of the collagen matrix, crystal size, trabecular orientation, special distribution of the different components and many more factors are all impacting bone strength. 6-14 Human cadaver studies have confirmed the correlation between bone density and bone. 26 strength. 5,15-20 Changes in cancellous bone morphology appear to lead to a disproportionate decrease in bone strength. 21-26 When postmenopausal women are stratified by age, obvious differences between BMD and actual fracture risk are observed. 24 Felsenberg eloquently summarizes what he calls the "Bone Quality Framework." In great detail he talks about the geometry and micro- architecture of bone and how the different components are related to functional stability. 27 Are our current testing modalities appropriately addressing these structural factors? Are we keeping in mind that in screening for osteoporosis the key variable is fragility, not bone density itself? All currently FDA approved and commercially available equipments for the evaluation of bone status claim that they - at least indirectly - assess the biological fracture risk. This review summarizes an extensive current literature research covering FDA approved as well as experimental devices for the evaluation of bone. The pros and cons of the different techniques are discussed in the context of diagnostic accuracies and practical implications.

Sex differences and growth-related adaptations in bone microarchitecture, geometry, density and strength from childhood to early adulthood: a mixed longitudinal HR-pQCT study

PubMed Central

Gabel, Leigh; Macdonald, Heather M.; McKay, Heather A.

2016-01-01

Sex differences in bone strength and fracture risk are well-documented. However, we know little about bone strength accrual during growth and adaptations in bone microstructure, density and geometry that accompany gains in bone strength. Thus, our objectives are to 1) describe growth related adaptations in bone microarchitecture, geometry, density and strength at the distal tibia and radius in boys and girls; 2) compare differences in adaptations in bone microarchitecture, geometry, density and strength between boys and girls. We used HR-pQCT at the distal tibia (8% site) and radius (7% site) in 184 boys and 209 girls (9–20y at baseline). We aligned boys and girls on a common maturational landmark (age at peak height velocity; APHV) and fit a mixed effects model to these longitudinal data. Importantly, boys demonstrated 28–63% greater estimated bone strength across 12 years of longitudinal growth. Boys demonstrated 28–80% more porous cortices compared with girls at both sites across all biological ages, except at the radius at 9 years post-APHV. However, cortical density was similar between boys and girls at all ages at both sites, except at 9 years post-APHV at the tibia when girls’ values were 2% greater than boys’. Boys demonstrated 13–48% greater cortical and total bone area across growth. Load-to-strength ratio was 26–27% lower in boys at all ages, indicating lower risk of distal forearm fracture compared with girls. Contrary to previous HR-pQCT studies that did not align boys and girls at the same biological age, we did not observe sex differences in Ct.BMD. Boys’ superior bone size and strength compared with girls may confer them a protective advantage. However, boys’ consistently more porous cortices may contribute to boys’ higher fracture incidence during adolescence. Large prospective studies using HR-pQCT that target boys and girls who have sustained a fracture are needed to verify this. PMID:27556581

Objectively measured physical activity and bone strength in 9-year-old boys and girls.

PubMed

Sardinha, Luís B; Baptista, Fátima; Ekelund, Ulf

2008-09-01

The purpose of this work was to analyze the relationship between intensity and duration of physical activity and composite indices of femoral neck strength and bone-mineral content of the femoral neck, lumbar spine, and total body. Physical activity was assessed by accelerometry in 143 girls and 150 boys (mean age: 9.7 years). Measurement of bone-mineral content, femoral neck bone-mineral density, femoral neck width, hip axis length, and total body fat-free mass was performed with dual-energy radiograph absorptiometry. Compressive [(bone-mineral density x femoral neck width/weight)] and bending strength [(bone-mineral density x femoral neck width(2))/(hip axis length x weight)] express the forces that the femoral neck has to withstand in weight bearing, whereas impact strength [(bone-mineral density x femoral neck width x hip axis length)/(height x weight)] expresses the energy that the femoral neck has to absorb in an impact from standing height. Analysis of covariance (fat-free mass and age adjusted) showed differences between boys and girls of approximately 9% for compressive, 10% for bending, and 9% for impact strength. Stepwise regression analysis using time spent at sedentary, light, moderate, and vigorous physical activity as predictors revealed that vigorous physical activity explained 5% to 9% of femoral neck strength variable variance in both genders, except for bending strength in boys, and approximately 1% to 3% of total body and femoral neck bone-mineral content variance. Vigorous physical activity was then used to categorize boys and girls into quartiles. Pairwise comparison indicated that boys in the third and fourth quartiles (accumulation of >26 minutes/day) demonstrated higher compressive (11%-12%), bending (10%), and impact (14%) strength than boys in the first quartile. In girls, comparison revealed a difference between the fourth (accumulation of >25 minutes/day) and first quartiles for bending strength (11%). We did not observe any relationship between physical activity and lumbar spine strength. Femoral neck strength is higher in boys than girls. Vigorous intensity emerged as the main physical activity predictor of femoral neck strength but did not explain gender differences. Daily vigorous physical activity for at least approximately 25 minutes seems to improve femoral neck bone health in children.

Naringin ameliorates bone loss induced by sciatic neurectomy and increases Semaphorin 3A expression in denervated bone.

PubMed

Ma, Xinlong; Lv, Jianwei; Sun, Xiaolei; Ma, Jianxiong; Xing, Guosheng; Wang, Ying; Sun, Lei; Wang, Jianbao; Li, Fengbo; Li, Yanjun; Zhao, Zhihu

2016-04-25

Naringin maintains bone mass in various osteoporosis models, while its effect on bone in disuse osteoporosis has not been reported. The present study explores whether naringin can prevent disuse osteoporosis induced by unilateral sciatic neurectomy (USN) and whether the Semaphorin 3A-induced Wnt/β-catenin signalling pathway is involved in the osteoprotection of naringin. Naringin dose-dependently prevented the deterioration of bone mineral density (BMD), trabecular structure and biomechanical strength in femur due to USN. Naringin increased bone formation but inhibited resorption, as indicated by bone-turnover markers in blood and urine and the histological staining of Osteocalcin (OCN) and tartrate-resistant acid phosphatase (TRAP) in femur. Semaphorin 3A (Sema3A) and active β-catenin protein decreased after USN and could be restored by naringin to the levels of the sham-operated rats. In addition, naringin in vitro promoted the differentiation of osteoblasts and inhibited osteoclastic differentiation. Our studies suggest that the down-regulation of Sema3A and the subsequent inactivation of Wnt/β-catenin signalling may be some of the mechanisms involved in USN-induced osteoporosis. Naringin could increase the expression of Sema3A and the activation of Wnt/β-catenin signalling to prevent disuse osteoporosis induced by denervation. Thus, naringin functions in bone maintenance and could be a promising therapeutic alternative in preventing disuse osteoporosis.

Naringin ameliorates bone loss induced by sciatic neurectomy and increases Semaphorin 3A expression in denervated bone

PubMed Central

Ma, Xinlong; Lv, Jianwei; Sun, Xiaolei; Ma, Jianxiong; Xing, Guosheng; Wang, Ying; Sun, Lei; Wang, Jianbao; Li, Fengbo; Li, Yanjun; Zhao, Zhihu

2016-01-01

Naringin maintains bone mass in various osteoporosis models, while its effect on bone in disuse osteoporosis has not been reported. The present study explores whether naringin can prevent disuse osteoporosis induced by unilateral sciatic neurectomy (USN) and whether the Semaphorin 3A-induced Wnt/β-catenin signalling pathway is involved in the osteoprotection of naringin. Naringin dose-dependently prevented the deterioration of bone mineral density (BMD), trabecular structure and biomechanical strength in femur due to USN. Naringin increased bone formation but inhibited resorption, as indicated by bone-turnover markers in blood and urine and the histological staining of Osteocalcin (OCN) and tartrate-resistant acid phosphatase (TRAP) in femur. Semaphorin 3A (Sema3A) and active β-catenin protein decreased after USN and could be restored by naringin to the levels of the sham-operated rats. In addition, naringin in vitro promoted the differentiation of osteoblasts and inhibited osteoclastic differentiation. Our studies suggest that the down-regulation of Sema3A and the subsequent inactivation of Wnt/β-catenin signalling may be some of the mechanisms involved in USN-induced osteoporosis. Naringin could increase the expression of Sema3A and the activation of Wnt/β-catenin signalling to prevent disuse osteoporosis induced by denervation. Thus, naringin functions in bone maintenance and could be a promising therapeutic alternative in preventing disuse osteoporosis. PMID:27109829

A protocol for a randomised controlled trial of the bone response to impact loading or resistance training in young women with lower than average bone mass: the OPTIMA-Ex trial

PubMed Central

Lambert, Conor; Beck, Belinda R; Harding, Amy T; Watson, Steven L; Weeks, Benjamin K

2017-01-01

Introduction The aim of the Osteoporosis Prevention Through Impact and Muscle-loading Approaches to Exercise trial is to compare the bone response to two known osteogenic stimuli — impact loading exercise and resistance training. Specifically, we will examine the effect of a 10-month, twice-weekly, high-intensity impact loading exercise intervention and a 10-month, twice-weekly, high-intensity resistance training intervention on bone mass and strength at clinically important skeletal sites. The intervention groups will be compared against a home-based ‘positive’ control group. Safety and acceptability of each exercise modality will also be determined. Methods and analysis Sedentary otherwise healthy young women aged 18–30 years with bone mineral density (BMD) T-scores less than or equal to 0 at the hip and lumbar spine, screened for conditions and medications that influence bone and physical function, will be recruited. Eligible participants are randomised to 10-month, twice-weekly, either supervised high-intensity impact training, high-intensity resistance training or a home-based ‘positive’ control group. The primary outcome measure will be lumbar spine areal BMD, while secondary outcome measures will include: whole body, femoral neck and regional measures (upper and lower limb) of bone, muscle and fat; anthropometrics; muscle strength and power; quality of life and exercise safety, enjoyment and acceptability. All outcome measures will be conducted at baseline (T0) and 10 months (T10) and will be analysed according to the intention-to-treat principle and per protocol. Ethics and dissemination The study has been granted ethical approval from the Griffith University Human Research Ethics Committee (GU Ref: 2015/775). Standard scientific reporting practices will occur, including publication in peer-reviewed journals. Participant confidentiality will be maintained in all forms of reporting. Trial registration number ACTRN12616001444471. PMID:28864705

Design and Fabrication of 3D printed Scaffolds with a Mechanical Strength Comparable to Cortical Bone to Repair Large Bone Defects

PubMed Central

Roohani-Esfahani, Seyed-Iman; Newman, Peter; Zreiqat, Hala

2016-01-01

A challenge in regenerating large bone defects under load is to create scaffolds with large and interconnected pores while providing a compressive strength comparable to cortical bone (100–150 MPa). Here we design a novel hexagonal architecture for a glass-ceramic scaffold to fabricate an anisotropic, highly porous three dimensional scaffolds with a compressive strength of 110 MPa. Scaffolds with hexagonal design demonstrated a high fatigue resistance (1,000,000 cycles at 1–10 MPa compressive cyclic load), failure reliability and flexural strength (30 MPa) compared with those for conventional architecture. The obtained strength is 150 times greater than values reported for polymeric and composite scaffolds and 5 times greater than reported values for ceramic and glass scaffolds at similar porosity. These scaffolds open avenues for treatment of load bearing bone defects in orthopaedic, dental and maxillofacial applications. PMID:26782020

Design and Fabrication of 3D printed Scaffolds with a Mechanical Strength Comparable to Cortical Bone to Repair Large Bone Defects

NASA Astrophysics Data System (ADS)

Roohani-Esfahani, Seyed-Iman; Newman, Peter; Zreiqat, Hala

2016-01-01

A challenge in regenerating large bone defects under load is to create scaffolds with large and interconnected pores while providing a compressive strength comparable to cortical bone (100-150 MPa). Here we design a novel hexagonal architecture for a glass-ceramic scaffold to fabricate an anisotropic, highly porous three dimensional scaffolds with a compressive strength of 110 MPa. Scaffolds with hexagonal design demonstrated a high fatigue resistance (1,000,000 cycles at 1-10 MPa compressive cyclic load), failure reliability and flexural strength (30 MPa) compared with those for conventional architecture. The obtained strength is 150 times greater than values reported for polymeric and composite scaffolds and 5 times greater than reported values for ceramic and glass scaffolds at similar porosity. These scaffolds open avenues for treatment of load bearing bone defects in orthopaedic, dental and maxillofacial applications.

Bone strength and athletic ability in hominids: Ardipithecus ramidus to Homo sapiens

NASA Astrophysics Data System (ADS)

Lee, Scott

2012-10-01

A methodology for the evaluation of the athletic ability of animals based on the strength of their femur and their body mass is developed. The ability of the femur to resist bending stresses is determined by its midlength cross-sectional geometry, its length and the elastic properties of the mineral part of the bone. The animal's athletic ability, determined by a ``bone strength index,'' is limited by this femoral bending strength in relation to the loads on the femur. This analysis is applied to the fossil record for Homo sapiens, Homo neanderthalensis, Homo erectus, Homo habilis, Australopithecus afarensis and Ardipithecus ramidus. Evidence that the femoral bone strength index of modern Homo sapiens has weakened over the last 50,000 years is found.

Greater association of peak neuromuscular performance with cortical bone geometry, bone mass and bone strength than bone density: A study in 417 older women.

PubMed

Belavý, Daniel L; Armbrecht, Gabriele; Blenk, Tilo; Bock, Oliver; Börst, Hendrikje; Kocakaya, Emine; Luhn, Franziska; Rantalainen, Timo; Rawer, Rainer; Tomasius, Frederike; Willnecker, Johannes; Felsenberg, Dieter

2016-02-01

We evaluated which aspects of neuromuscular performance are associated with bone mass, density, strength and geometry. 417 women aged 60-94years were examined. Countermovement jump, sit-to-stand test, grip strength, forearm and calf muscle cross-sectional area, areal bone mineral content and density (aBMC and aBMD) at the hip and lumbar spine via dual X-ray absorptiometry, and measures of volumetric vBMC and vBMD, bone geometry and section modulus at 4% and 66% of radius length and 4%, 38% and 66% of tibia length via peripheral quantitative computed tomography were performed. The first principal component of the neuromuscular variables was calculated to generate a summary neuromuscular variable. Percentage of total variance in bone parameters explained by the neuromuscular parameters was calculated. Step-wise regression was also performed. At all pQCT bone sites (radius, ulna, tibia, fibula), a greater percentage of total variance in measures of bone mass, cortical geometry and/or bone strength was explained by peak neuromuscular performance than for vBMD. Sit-to-stand performance did not relate strongly to bone parameters. No obvious differential in the explanatory power of neuromuscular performance was seen for DXA aBMC versus aBMD. In step-wise regression, bone mass, cortical morphology, and/or strength remained significant in relation to the first principal component of the neuromuscular variables. In no case was vBMD positively related to neuromuscular performance in the final step-wise regression models. Peak neuromuscular performance has a stronger relationship with leg and forearm bone mass and cortical geometry as well as proximal forearm section modulus than with vBMD. Copyright © 2015 Elsevier Inc. All rights reserved.

Myostatin deficiency partially rescues the bone phenotype of osteogenesis imperfecta model mice.

PubMed

Oestreich, A K; Carleton, S M; Yao, X; Gentry, B A; Raw, C E; Brown, M; Pfeiffer, F M; Wang, Y; Phillips, C L

2016-01-01

Mice with osteogenesis imperfecta (+/oim), a disorder of bone fragility, were bred to mice with muscle over growth to test whether increasing muscle mass genetically would improve bone quality and strength. The results demonstrate that femora from mice carrying both mutations have greater mechanical integrity than their +/oim littermates. Osteogenesis imperfecta is a heritable connective tissue disorder due primarily to mutations in the type I collagen genes resulting in skeletal deformity and fragility. Currently, there is no cure, and therapeutic strategies encompass the use of antiresorptive pharmaceuticals and surgical bracing, with limited success and significant potential for adverse effects. Bone, a mechanosensing organ, can respond to high mechanical loads by increasing new bone formation and altering bone geometry to withstand increased forces. Skeletal muscle is a major source of physiological loading on bone, and bone strength is proportional to muscle mass. To test the hypothesis that congenic increases in muscle mass in the osteogenesis imperfecta murine model mouse (oim) will improve their compromised bone quality and strength, heterozygous (+/oim) mice were bred to mice deficient in myostatin (+/mstn), a negative regulator of muscle growth. The resulting adult offspring were evaluated for hindlimb muscle mass, and bone microarchitecture, physiochemistry, and biomechanical integrity. +/oim mice deficient in myostatin (+/mstn +/oim) were generated and demonstrated that myostatin deficiency increased body weight, muscle mass, and biomechanical strength in +/mstn +/oim mice as compared to +/oim mice. Additionally, myostatin deficiency altered the physiochemical properties of the +/oim bone but did not alter bone remodeling. Myostatin deficiency partially improved the reduced femoral bone biomechanical strength of adult +/oim mice by increasing muscle mass with concomitant improvements in bone microarchitecture and physiochemical properties.

High Salt Diets, Bone Strength and Mineral Content of Mature Femur After Skeletal Unloading

NASA Technical Reports Server (NTRS)

Liang, Michael T. C.

1998-01-01

It is known that high salt diets increase urinary calcium (Ca) loss, but it is not known whether this effect weakens bone during space flight. The Bone Hormone Lab has studied the effect of high salt diets on Ca balance and whole body Ca in a space flight model (2,8). Neither the strength nor mineral content of the femurs from these studies has been evaluated. The purpose of this study was to determine the effect of high salt diets (HiNa) and skeletal unloading on femoral bone strength and bone mineral content (BMC) in mature rats.

Direct ink writing of highly porous and strong glass scaffolds for load-bearing bone defects repair and regeneration.

PubMed

Fu, Qiang; Saiz, Eduardo; Tomsia, Antoni P

2011-10-01

The quest for synthetic materials to repair load-bearing bone lost because of trauma, cancer, or congenital bone defects requires the development of porous, high-performance scaffolds with exceptional mechanical strength. However, the low mechanical strength of porous bioactive ceramic and glass scaffolds, compared with that of human cortical bone, has limited their use for these applications. In the present work bioactive 6P53B glass scaffolds with superior mechanical strength were fabricated using a direct ink writing technique. The rheological properties of Pluronic® F-127 (referred to hereafter simply as F-127) hydrogel-based inks were optimized for the printing of features as fine as 30 μm and of three-dimensional scaffolds. The mechanical strength and in vitro degradation of the scaffolds were assessed in a simulated body fluid (SBF). The sintered glass scaffolds showed a compressive strength (136 ± 22 MPa) comparable with that of human cortical bone (100-150 MPa), while the porosity (60%) was in the range of that of trabecular bone (50-90%). The strength is ~100-times that of polymer scaffolds and 4-5-times that of ceramic and glass scaffolds with comparable porosities. Despite the strength decrease resulting from weight loss during immersion in SBF, the value (77 MPa) is still far above that of trabecular bone after 3 weeks. The ability to create both porous and strong structures opens a new avenue for fabricating scaffolds for load-bearing bone defect repair and regeneration. Published by Elsevier Ltd.

Direct Ink Writing of Highly Porous and Strong Glass Scaffolds for Load-bearing Bone Defects Repair and Regeneration

PubMed Central

Fu, Qiang; Saiz, Eduardo; Tomsia, Antoni P.

2011-01-01

The quest for synthetic materials to repair load-bearing bone lost because of trauma, cancer, or congenital bone defects requires development of porous and high-performance scaffolds with exceptional mechanical strength. However, the low mechanical strength of porous bioactive ceramic and glass scaffolds, compared with that of human cortical bone, has limited their use for these applications. In the present work, bioactive 6P53B glass scaffolds with superior mechanical strength were fabricated using a direct ink writing technique. The rheological properties of Pluronic® F-127 (referred to hereafter simply as F-127) hydrogel-based inkswere optimized for the printing of features as fine as 30 μm and of the three-dimensional scaffolds. The mechanical strength and in vitro degradation of the scaffolds were assessed in a simulated body fluid (SBF). The sintered glass scaffolds show a compressive strength (136 ± 22 MPa) comparable to that of human cortical bone (100-150 MPa), while the porosity (60%) is in the range of that of trabecular bone (50-90%).The strength is ~100 times that of polymer scaffolds and 4–5 times that of ceramic and glass scaffolds with comparable porosities. Despite the strength decrease resulting from weight loss during immersion in an SBF, the value (77 MPa) is still far above that of trabecular bone after three weeks. The ability to create both porous and strong structures opens a new avenue for fabricating scaffolds for load-bearing bone defect repair and regeneration. PMID:21745606

Adult Bone Strength of Children from Single-Parent Families: The Midlife in the U.S. Study

PubMed Central

Crandall, Carolyn J.; Karlamangla, Arun S.; Merkin, Sharon Stein; Binkley, Neil; Carr, Deborah; Greendale, Gail A.; Seeman, Teresa E.

2015-01-01

Purpose Because peak bone mass is acquired during childhood, bone health may be negatively impacted by childhood socio-environmental disadvantage. The goal of this study was to determine whether being raised in a single-parent household is associated with lower bone strength in adulthood. Methods Using dual-energy x-ray absorptiometry data from 708 participants (mean age 57 years) in the Midlife in the United States Biomarker Project, we examined the independent associations of composite indices of femoral neck bone strength relative to load (in three failure modes: compression, bending, and impact) in adulthood with the experience of single-parent childhood and parental death or divorce in childhood. Results After adjustment for gender, race, menopause transition stage, age, and body mass index, each additional year of single-parent childhood was associated with 0.02 to 0.03 SD lower indices of adult femoral neck strength. In those with 9-16 years of single-parent childhood, the compression strength index was 0.41 SD lower, bending strength index was 0.31 SD lower, and impact strength index was 0.25 SD lower (all p-values < 0.05). In contrast, parental death or divorce during childhood was not by itself independently associated with adult bone strength indices. The magnitudes of these associations were unaltered by additional adjustment for lifestyle factors and socioeconomic status in childhood and adulthood. Conclusions Independent of parental death or divorce, growing up in a single-parent household is associated with lower femoral neck bone strength in adulthood, and this association is not entirely explained by childhood or adult socioeconomic conditions or lifestyle choices. PMID:25510582

Distal radius geometry and skeletal strength indices after peripubertal artistic gymnastics.

PubMed

Dowthwaite, J N; Scerpella, T A

2011-01-01

Development of optimal skeletal strength should decrease adult bone fragility. Nongymnasts (NON): were compared with girls exposed to gymnastics during growth (EX/GYM: ), using peripheral quantitative computed tomography (pQCT) to evaluate postmenarcheal bone geometry, density, and strength. Pre- and perimenarcheal gymnastic loading yields advantages in indices of postmenarcheal bone geometry and skeletal strength. Two prior studies using pQCT have reported bone density and size advantages in Tanner I/II gymnasts, but none describe gymnasts' bone properties later in adolescence. The current study used pQCT to evaluate whether girls exposed to gymnastics during late childhood growth and perimenarcheal growth exhibited greater indices of distal radius geometry, density, and skeletal strength. Postmenarcheal subjects underwent 4% and 33% distal radius pQCT scans, yielding: 1) vBMD and cross-sectional areas (CSA) (total bone, compartments); 2) polar strength-strain index; 3) index of structural strength in axial compression. Output was compared for EX/GYM: vs. NON: , adjusting for gynecological age and stature (maturity and body size), reporting means, standard errors, and significance. Sixteen postmenarcheal EX/GYM: (age 16.7 years; gynecological age 3.4 years) and 13 NON: (age 16.2 years; gynecological age 3.6 years) were evaluated. At both diaphysis and metaphysis, EX/GYM: exhibited greater CSA and bone strength indices than NON; EX/GYM: exhibited 79% larger intramedullary CSA than NON: (p < 0.05). EX/GYM: had significantly higher 4% trabecular vBMD; differences were not detected for 4% total vBMD and 33% cortical vBMD. Following pre-/perimenarcheal gymnastic exposure, relative to nongymnasts, postmenarcheal EX/GYM: demonstrated greater indices of distal radius geometry and skeletal strength (metaphysis and diaphysis) with greater metaphyseal trabecular vBMD; larger intramedullary cavity size was particularly striking.

Distal radius geometry and skeletal strength indices after peripubertal artistic gymnastics

PubMed Central

Scerpella, T. A.

2011-01-01

Summary Development of optimal skeletal strength should decrease adult bone fragility. Nongymnasts (NON) were compared with girls exposed to gymnastics during growth (EX/GYM), using peripheral quantitative computed tomography (pQCT) to evaluate postmenarcheal bone geometry, density, and strength. Pre- and perimenarcheal gymnastic loading yields advantages in indices of postmenarcheal bone geometry and skeletal strength. Introduction Two prior studies using pQCT have reported bone density and size advantages in Tanner I/II gymnasts, but none describe gymnasts’ bone properties later in adolescence. The current study used pQCT to evaluate whether girls exposed to gymnastics during late childhood growth and perimenarcheal growth exhibited greater indices of distal radius geometry, density, and skeletal strength. Methods Postmenarcheal subjects underwent 4% and 33% distal radius pQCT scans, yielding: 1) vBMD and cross-sectional areas (CSA) (total bone, compartments); 2) polar strength-strain index; 3) index of structural strength in axial compression. Output was compared for EX/GYM vs. NON, adjusting for gynecological age and stature (maturity and body size), reporting means, standard errors, and significance. Results Sixteen postmenarcheal EX/GYM (age 16.7 years; gynecological age 3.4 years) and 13 NON (age 16.2 years; gynecological age 3.6 years) were evaluated. At both diaphysis and metaphysis, EX/GYM exhibited greater CSA and bone strength indices than NON; EX/GYM exhibited 79% larger intramedullary CSA than NON (p<0.05). EX/GYM had significantly higher 4% trabecular vBMD; differences were not detected for 4% total vBMD and 33% cortical vBMD. Conclusions Following pre-/perimenarcheal gymnastic exposure, relative to nongymnasts, postmenarcheal EX/GYM demonstrated greater indices of distal radius geometry and skeletal strength (metaphysis and diaphysis) with greater metaphyseal trabecular vBMD; larger intramedullary cavity size was particularly striking. PMID:20419293

Lithium doped calcium phosphate cement maintains physical mechanical properties and promotes osteoblast proliferation and differentiation.

PubMed

Li, Li; Wang, Renchong; Li, Baichuan; Liang, Wei; Pan, Haobo; Cui, Xu; Tang, Jingli; Li, Bing

2017-07-01

Calcium phosphate cement (CPC) has been widely used in bone tissue repairing due to its physical mechanical properties and biocompatibility. Addition of trace element to CPC has shown promising evidence to improve the physical properties and biological activities of CPC. Lithium (Li) has effect on osteoblast proliferation and differentiation. In this study, we incorporated Li to CPC and examined the physical properties of Li/CPC and its effect on osteoblast proliferation and differentiation. We found that Li doped CPC maintained similar setting time, pore size distribution, compressive strength, composition, and morphology as CPC without Li. Additionally, Li doped CPC improved osteoblast proliferation and differentiation significantly compared to CPC without Li. To our knowledge, our results, for the first time, show that Li doped CPC has beneficial effect on osteoblast in cell culture while keeps the excellent physical-mechanical properties of CPC. This study will lead to potential application of Li doped CPC in bone tissue engineering. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 944-952, 2017. © 2016 Wiley Periodicals, Inc.

Variability of the pullout strength of cancellous bone screws with cement augmentation.

PubMed

Procter, P; Bennani, P; Brown, C J; Arnoldi, J; Pioletti, D P; Larsson, S

2015-06-01

Orthopaedic surgeons often face clinical situations where improved screw holding power in cancellous bone is needed. Injectable calcium phosphate cements are one option to enhance fixation. Paired screw pullout tests were undertaken in which human cadaver bone was augmented with calcium phosphate cement. A finite element model was used to investigate sensitivity to screw positional placement. Statistical analysis of the data concluded that the pullout strength was generally increased by cement augmentation in the in vitro human cadaver tests. However, when comparing the individual paired samples there were surprising results with lower strength than anticipated after augmentation, in apparent contradiction to the generally expected conclusion. Investigation using the finite element model showed that these strength reductions could be accounted for by small screw positional changes. A change of 0.5mm might result in predicted pullout force changes of up to 28%. Small changes in screw position might lead to significant changes in pullout strength sufficient to explain the lower than expected individual pullout values in augmented cancellous bone. Consequently whilst the addition of cement at a position of low strength would increase the pullout strength at that point, it might not reach the pullout strength of the un-augmented paired test site. However, the overall effect of cement augmentation produces a significant improvement at whatever point in the bone the screw is placed. The use of polymeric bone-substitute materials for tests may not reveal the natural variation encountered in tests using real bone structures. Copyright © 2015 Elsevier Ltd. All rights reserved.

Enhanced bone regeneration using an insulin-loaded nano-hydroxyapatite/collagen/PLGA composite scaffold.

PubMed

Wang, Xing; Zhang, Guilan; Qi, Feng; Cheng, Yongfeng; Lu, Xuguang; Wang, Lu; Zhao, Jing; Zhao, Bin

2018-01-01

Insulin is widely considered as a classical hormone and drug in maintaining energy and glucose homeostasis. Recently, insulin has been increasingly recognized as an indispensable factor for osteogenesis and bone turnover, but its applications in bone regeneration have been restricted because of the short periods of activity and uncontrolled release. In this study, we incorporated insulin-loaded poly lactic-co-glycolic-acid (PLGA) nanospheres into nano-hydroxyapatite/collagen (nHAC) scaffolds and investigated the bioactivity of the composite scaffolds in vitro and in vivo. Bioactive insulin was successfully released from the nanospheres within the scaffold, and the release kinetics of insulin could be efficiently controlled by uniform-sized nanospheres. The physical characterizations of the composite scaffolds demonstrated that incorporation of nanospheres in nHAC scaffolds using this method did not significantly change the porosity, pore diameters, and compressive strengths of nHAC. In vitro, the insulin-loaded nHAC/PLGA composite scaffolds possessed favorable biological function for bone marrow mesenchymal stem cells adhesion and proliferation, as well as the differentiation into osteoblasts. In vivo, the optimized bone regenerative capability of this composite scaffold was confirmed in rabbit mandible critical size defects. These results demonstrated successful development of a functional insulin-PLGA-nHAC composite scaffold that enhances the bone regeneration capability of nHAC.

The Role of GH/IGF-I Axis in Muscle Homeostasis During Weightlessness

NASA Technical Reports Server (NTRS)

Schwartz, Robert J.

1997-01-01

Exposure to reduced gravity during space travel profoundly alters the loads placed on bone and muscle. Astronauts suffer significant losses of muscle and bone strength during weightlessness. Exercise as a countermeasure is only partially effective in remedying severe muscle atrophy and bone demineralization. Similar wasting of muscles and bones affects people on Earth during prolonged bed rest or immobilization due to injury. In the absence of weight bearing activity, atrophy occurs primarily in the muscles that act in low power, routine movements and in maintaining posture. Hormonal disfunction could contribute in part to the loss of muscle and bone during spaceflight. Reduced levels of human Growth Hormone (hGH) were found in astronauts during space flight, as well as reduced GH secretory activity was observed from the anterior pituitary in 7-day space flight rats. Growth hormone has been shown to be required for maintenance of muscle mass and bone mineralization, in part by mediating the biosynthesis IGF-I, a small polypeptide growth factor. IGF biosynthesis and secretion plays an important role in potentiating muscle cell differentiation and has been shown to drive the expression of myogenin, a myogenic specific basic helix-loop-helix factor. IGF-I has also been shown to have an important role in potentiating muscle regeneration, repair and adult muscle hypertrophy.

Insulin resistance and bone strength: findings from the study of midlife in the United States.

PubMed

Srikanthan, Preethi; Crandall, Carolyn J; Miller-Martinez, Dana; Seeman, Teresa E; Greendale, Gail A; Binkley, Neil; Karlamangla, Arun S

2014-04-01

Although several studies have noted increased fracture risk in individuals with type 2 diabetes mellitus (T2DM), the pathophysiologic mechanisms underlying this association are not known. We hypothesize that insulin resistance (the key pathology in T2DM) negatively influences bone remodeling and leads to reduced bone strength. Data for this study came from 717 participants in the Biomarker Project of the Midlife in the United States Study (MIDUS II). The homeostasis model assessment of insulin resistance (HOMA-IR) was calculated from fasting morning blood glucose and insulin levels. Projected 2D (areal) bone mineral density (BMD) was measured in the lumbar spine and left hip using dual-energy X-ray absorptiometry (DXA). Femoral neck axis length and width were measured from the hip DXA scans, and combined with BMD and body weight and height to create composite indices of femoral neck strength relative to load in three different failure modes: compression, bending, and impact. We used multiple linear regressions to examine the relationship between HOMA-IR and bone strength, adjusted for age, gender, race/ethnicity, menopausal transition stage (in women), and study site. Greater HOMA-IR was associated with lower values of all three composite indices of femoral neck strength relative to load, but was not associated with BMD in the femoral neck. Every doubling of HOMA-IR was associated with a 0.34 to 0.40 SD decrement in the strength indices (p<0.001). On their own, higher levels of fasting insulin (but not of glucose) were independently associated with lower bone strength. Our study confirms that greater insulin resistance is related to lower femoral neck strength relative to load. Further, we note that hyperinsulinemia, rather than hyperglycemia, underlies this relationship. Although cross-sectional associations do not prove causality, our findings do suggest that insulin resistance and in particular, hyperinsulinemia, may negatively affect bone strength relative to load. © 2014 American Society for Bone and Mineral Research.

High strength, surface porous polyether-ether-ketone for load-bearing orthopaedic implants

PubMed Central

Evans, Nathan T.; Torstrick, F. Brennan; Lee, Christopher S.D.; Dupont, Kenneth M.; Safranski, David L.; Chang, W. Allen; Macedo, Annie E.; Lin, Angela; Boothby, Jennifer M.; Whittingslow, Daniel C.; Carson, Robert A.; Guldberg, Robert E.; Gall, Ken

2015-01-01

Despite its widespread clinical use in load-bearing orthopaedic implants, polyether-ether-ketone (PEEK) is often associated with poor osseointegration. In this study, a surface porous PEEK material (PEEK-SP) was created using a melt extrusion technique. The porous layer thickness was 399.6±63.3 µm and possessed a mean pore size of 279.9±31.6 µm, strut spacing of 186.8±55.5 µm, porosity of 67.3±3.1%, and interconnectivity of 99.9±0.1%. Monotonic tensile tests showed that PEEK-SP preserved 73.9% of the strength (71.06±2.17 MPa) and 73.4% of the elastic modulus (2.45±0.31 GPa) of as-received, injection molded PEEK. PEEK-SP further demonstrated a fatigue strength of 60.0 MPa at one million cycles, preserving 73.4% of the fatigue resistance of injection molded PEEK. Interfacial shear testing showed the pore layer shear strength to be 23.96±2.26 MPa. An osseointegration model in the rat revealed substantial bone formation within the pore layer at 6 and 12 weeks via µCT and histological evaluation. Ingrown bone was more closely apposed to the pore wall and fibrous tissue growth was reduced in PEEK-SP when compared to non-porous PEEK controls. These results indicate that PEEK-SP could provide improved osseointegration while maintaining the structural integrity necessary for load-bearing orthopaedic applications. PMID:25463499

Smad4 is required to inhibit osteoclastogenesis and maintain bone mass.

PubMed

Morita, Mayu; Yoshida, Shigeyuki; Iwasaki, Ryotaro; Yasui, Tetsuro; Sato, Yuiko; Kobayashi, Tami; Watanabe, Ryuichi; Oike, Takatsugu; Miyamoto, Kana; Takami, Masamichi; Ozato, Keiko; Deng, Chu-Xia; Aburatani, Hiroyuki; Tanaka, Sakae; Yoshimura, Akihiko; Toyama, Yoshiaki; Matsumoto, Morio; Nakamura, Masaya; Kawana, Hiromasa; Nakagawa, Taneaki; Miyamoto, Takeshi

2016-10-12

Bone homeostasis is maintained as a delicate balance between bone-resorption and bone-formation, which are coupled to maintain appropriate bone mass. A critical question is how bone-resorption is terminated to allow bone-formation to occur. Here, we show that TGFβs inhibit osteoclastogenesis and maintain bone-mass through Smad4 activity in osteoclasts. We found that latent-TGFβ1 was activated by osteoclasts to inhibit osteoclastogenesis. Osteoclast-specific Smad4 conditional knockout mice (Smad4-cKO) exhibited significantly reduced bone-mass and elevated osteoclast formation relative to controls. TGFβ1-activation induced expression of Irf8 and Bcl6, both of which encode factors inhibiting osteoclastogenesis, by blocking their negative regulator, Prdm1, in osteoclasts in a Smad4-dependent manner. Reduced bone-mass and accelerated osteoclastogenesis seen in Smad4-cKO were abrogated by Prdm1 deletion. Administration of latent-TGFβ1-Fc to wild-type mice antagonized LPS-induced bone destruction in a model of activated osteoclast-mediated bone destruction. Thus, latent-TGFβ1-Fc could serve as a promising new therapeutic agent in bone diseases marked by excessive resorption.

Later Age at Onset of Independent Walking Is Associated With Lower Bone Strength at Fracture-Prone Sites in Older Men.

PubMed

Ireland, Alex; Muthuri, Stella; Rittweger, Joern; Adams, Judith E; Ward, Kate A; Kuh, Diana; Cooper, Rachel

2017-06-01

Later age at onset of independent walking is associated with lower leg bone strength in childhood and adolescence. However, it is unknown whether these associations persist into older age or whether they are evident at axial (central) or upper limb sites. Therefore, we examined walking age obtained at age 2 years and bone outcomes obtained by dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) scans at ages 60 to 64 years in a nationally representative cohort study of British people, the MRC National Survey of Health and Development. It was hypothesized that later walking age would be associated with lower bone strength at all sites. Later independent walking age was associated with lower height-adjusted hip (standardized regression coefficients with 95% confidence interval [CI] -0.179 [-0.251 to -0.107]), spine (-0.157 [-0.232 to -0.082]), and distal radius (-0.159 [-0.245 to -0.073]) bone mineral content (BMC, indicating bone compressive strength) in men (all p < 0.001). Adjustment for covariates partially attenuated these associations, primarily because of lower lean mass and adolescent sporting ability in later walkers. These associations were also evident for a number of hip geometric parameters (including cross-sectional moment of inertia [CSMI], indicating bone bending/torsional strength) assessed by hip structural analysis (HSA) from DXA scans. Similar height-adjusted associations were also observed in women for several hip, spine, and upper limb outcomes, although adjustment for fat or lean mass led to complete attenuation for most outcomes, with the exception of femoral shaft CSMI and spine bone area (BA). In conclusion, later independent walking age appears to have a lifelong association with bone strength across multiple skeletal sites in men. These effects may result from direct effects of early life loading on bone growth and mediation by adult body composition. Results suggest that late walking age may represent a novel risk factor for subsequent low bone strength. Existing interventions effective in hastening walking age may have positive effects on bone across life. © 2017 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc. © 2017 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.

HyBAR: hybrid bone-attached robot for joint arthroplasty.

PubMed

Song, S; Mor, A; Jaramaz, B

2009-06-01

A number of small bone-attached surgical robots have been introduced to overcome some disadvantages of large stand-alone surgical robots. In orthopaedics, increasing demand on minimally invasive joint replacement surgery has also been encouraging small surgical robot developments. Among various technical aspects of such an approach, optimal miniaturization that maintains structural strength for high speed bone removal was investigated. By observing advantages and disadvantages from serial and parallel robot structures, a new hybrid kinematic configuration was designed for a bone-attached robot to perform precision bone removal for cutting the femoral implant cavity during patellofemoral joint arthroplasty surgery. A series of experimental tests were conducted in order to evaluate the performance of the new robot, especially with respect to accuracy of bone preparation. A miniaturized and rigidly-structured robot prototype was developed for minimally invasive bone-attached robotic surgery. A new minimally invasive modular clamping system was also introduced to enhance the robotic procedure. Foam and pig bone experimental results demonstrated a successful implementation of the new robot that eliminated a number of major design problems of a previous prototype. For small bone-attached surgical robots that utilize high speed orthopaedic tools, structural rigidity and clamping mechanism are major design issues. The new kinematic configuration using hinged prismatic joints enabled an effective miniaturization with good structural rigidity. Although minor problems still exist at the prototype stage, the new development would be a significant step towards the practical use of such a robot.

A new stable GIP-Oxyntomodulin hybrid peptide improved bone strength both at the organ and tissue levels in genetically-inherited type 2 diabetes mellitus.

PubMed

Mansur, Sity Aishah; Mieczkowska, Aleksandra; Flatt, Peter R; Bouvard, Beatrice; Chappard, Daniel; Irwin, Nigel; Mabilleau, Guillaume

2016-06-01

Obesity and type 2 diabetes mellitus (T2DM) progress worldwide with detrimental effects on several physiological systems including bone tissue mainly by affecting bone quality. Several gut hormones analogues have been proven potent in ameliorating bone quality. In the present study, we used the leptin receptor-deficient db/db mice as a model of obesity and severe T2DM to assess the extent of bone quality alterations at the organ and tissue levels. We also examined the beneficial effects of gut hormone therapy in this model by using a new triple agonist ([d-Ala(2)]GIP-Oxm) active at the GIP, GLP-1 and glucagon receptors. As expected, db/db mice presented with dramatic alterations of bone strength at the organ level associated with deterioration of trabecular and cortical microarchitectures and an augmentation in osteoclast numbers. At the tissue level, these animals presented also with alterations of bone strength (reduced hardness, indentation modulus and dissipated energy) with modifications of tissue mineral distribution, collagen glycation and collagen maturity. The use of [d-Ala(2)]GIP-Oxm considerably improved bone strength at the organ level with modest effects on trabecular microarchitecture. At the tissue level, [d-Ala(2)]GIP-Oxm ameliorated bone strength reductions with positive effects on collagen glycation and collagen maturity. This study provides support for including gut hormone analogues as possible new therapeutic strategies for improving bone quality in bone complications associated to T2DM. Copyright © 2016 Elsevier Inc. All rights reserved.

A feasibility study for in vitro evaluation of fixation between prosthesis and bone with bone marrow-derived mesenchymal stem cells.

PubMed

Morita, Yusuke; Yamasaki, Kenichi; Hattori, Koji

2010-10-01

It is difficult to quantitatively evaluate adhesive strength between an implant and the neighboring bone using animal experiments, because the degree of fixation of an implant depends on differences between individuals and the clearance between the material and the bone resulting from surgical technique. A system was designed in which rat bone marrow cells were used to quantitatively evaluate the adhesion between titanium alloy plates and bone plates in vitro. Three kinds of surface treatment were used: a sand-blasted surface, a titanium-sprayed surface and a titanium-sprayed surface coated with hydroxyapatite. Bone marrow cells obtained from rat femora were seeded on the titanium alloy plates, and the cells were cultured between the titanium alloy plates and the bone plates sliced from porcine ilium for 2 weeks. After cultivation, adhesive strength was measured using a tensile test, after which DNA amount and Alkaline phosphatase activity were measured. The seeded cells accelerated adhesion of the titanium alloy plate to the bone plate. Adhesive strength of the titanium-sprayed surface was lower than that of the sand-blasted surface because of lower initial contact area, although there was no difference in Alkaline phosphatase activity between two surface treatments. A hydroxyapatite coating enhanced adhesive strength between the titanium alloy palate and the bone plate, as well as enhancing osteogenic differentiation of bone marrow cells. It is believed that this novel experimental method can be used to simultaneously evaluate the osteogenic differentiation and the adhesive strength of an implant during in vitro cultivation. 2010 Elsevier Ltd. All rights reserved.

Deficits in distal radius bone strength, density and microstructure are associated with forearm fractures in girls: an HR-pQCTstudy

PubMed Central

Määttä, M.; Macdonald, H. M.; Mulpuri, K.

2016-01-01

Summary Forearm fractures are common during growth. We studied bone strength in youth with a recent forearm fracture. In girls, suboptimal bone strength was associated with fractures. In boys, poor balance and physical inactivity may lead to fractures. Prospective studies will confirm these relationships and identify targets for prevention strategies. Introduction The etiology of pediatric forearm fractures is unclear. Thus, we examined distal radius bone strength, microstructure, and density in children and adolescents with a recent low- or moderate-energy forearm fracture and those without forearm fractures. Methods We assessed the non-dominant (controls) and non-fractured (cases) distal radius (7 % site) using high-resolution peripheral quantitative computed tomography (HR-pQCT) (Scanco Medical AG) in 270 participants (girls: cases n=47, controls n=61 and boys: cases n=88, controls n=74) aged 8–16 years. We assessed standard anthropometry, maturity, body composition (dual energy X-ray absorptiometry (DXA), Hologic QDR 4500 W) physical activity, and balance. We fit sex-specific logistic regression models for each bone outcome adjusting for maturity, ethnicity, height, and percent body fat. Results In girls, impaired bone strength (failure load, ultimate stress) and a high load-to-strength ratio were associated with low-energy fractures (odds ratios (OR) 2.8–4.3). Low total bone mineral density (Tt.BMD), bone volume ratio, trabecular thickness, and cortical BMD and thickness were also associated with low-energy fractures (ORs 2.0–7.0). In boys, low Tt.BMD, but not bone strength, was associated with low-energy fractures (OR=1.8). Boys with low-energy fractures had poor balance and higher percent body fat compared with controls (p<0.05). Boys with fractures (both types) were less active than controls (p<0.05). Conclusions Forearm fracture etiology appears to be sex-specific. In girls, deficits in bone strength are associated with fractures. In boys, a combination of poor balance, excess body fat, and low physical activity may lead to fractures. Prospective studies are needed to confirm these relationships and clarify targets for prevention strategies. PMID:25572041

Balancing the Rates of New Bone Formation and Polymer Degradation Enhances Healing of Weight-Bearing Allograft/Polyurethane Composites in Rabbit Femoral Defects

PubMed Central

Dumas, Jerald E.; Prieto, Edna M.; Zienkiewicz, Katarzyna J.; Guda, Teja; Wenke, Joseph C.; Bible, Jesse; Holt, Ginger E.

2014-01-01

There is a compelling clinical need for bone grafts with initial bone-like mechanical properties that actively remodel for repair of weight-bearing bone defects, such as fractures of the tibial plateau and vertebrae. However, there is a paucity of studies investigating remodeling of weight-bearing bone grafts in preclinical models, and consequently there is limited understanding of the mechanisms by which these grafts remodel in vivo. In this study, we investigated the effects of the rates of new bone formation, matrix resorption, and polymer degradation on healing of settable weight-bearing polyurethane/allograft composites in a rabbit femoral condyle defect model. The grafts induced progressive healing in vivo, as evidenced by an increase in new bone formation, as well as a decrease in residual allograft and polymer from 6 to 12 weeks. However, the mismatch between the rates of autocatalytic polymer degradation and zero-order (independent of time) new bone formation resulted in incomplete healing in the interior of the composite. Augmentation of the grafts with recombinant human bone morphogenetic protein-2 not only increased the rate of new bone formation, but also altered the degradation mechanism of the polymer to approximate a zero-order process. The consequent matching of the rates of new bone formation and polymer degradation resulted in more extensive healing at later time points in all regions of the graft. These observations underscore the importance of balancing the rates of new bone formation and degradation to promote healing of settable weight-bearing bone grafts that maintain bone-like strength, while actively remodeling. PMID:23941405

FACILE SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL ACTIVITY OF CELLULOSE-CHITOSAN-HYDROXYAPATITE COMPOSITE MATERIAL, A POTENTIAL MATERIAL FOR BONE TISSUE ENGINEERING

PubMed Central

Mututuvari, Tamutsiwa M.; Harkins, April L.

2013-01-01

Hydroxyapatite (HAp) is often used as a bone-implant material because it is biocompatible and osteoconductive. However, HAp possesses poor rheological properties and it is inactive against disease-causing microbes. To improve these properties, we developed a green method to synthesize multifunctional composites containing: (1) cellulose (CEL) to impart mechanical strength; (2) chitosan (CS) to induce antibacterial activity thereby maintaining a microbe-free wound site; and (3) HAp. In this method, CS and CEL were co-dissolved in an ionic liquid (IL) and then regenerated from water. HAp was subsequently formed in situ by alternately soaking [CEL+CS] composites in aqueous solutions of CaCl2 and Na2HPO4. At least 88% of IL used was recovered for reuse by distilling the aqueous washings of [CEL+CS]. The composites were characterized using FTIR, XRD and SEM. These composites retained the desirable properties of their constituents. For example, the tensile strength of the composites was enhanced 1.9X by increasing CEL loading from 20% to 80%. Incorporating CS in the composites resulted in composites which inhibited the growth of both Gram positive (MRSA, S. aureus and VRE) and Gram negative (E. coli and P. aeruginosa) bacteria. These findings highlight the potential use of [CEL+CS+HAp] composites as scaffolds in bone tissue engineering. PMID:23595871

Chitosan composite three dimensional macrospheric scaffolds for bone tissue engineering.

PubMed

Vyas, Veena; Kaur, Tejinder; Thirugnanam, Arunachalam

2017-11-01

The present work deals with the fabrication of chitosan composite scaffolds with controllable and predictable internal architecture for bone tissue engineering. Chitosan (CS) based composites were developed by varying montmorillonite (MMT) and hydroxyapatite (HA) combinations to fabricate macrospheric three dimensional (3D) scaffolds by direct agglomeration of the sintered macrospheres. The fabricated CS, CS/MMT, CS/HA and CS/MMT/HA 3D scaffolds were characterized for their physicochemical, biological and mechanical properties. The XRD and ATR-FTIR studies confirmed the presence of the individual constituents and the molecular interaction between them, respectively. The reinforcement with HA and MMT showed reduced swelling and degradation rate. It was found that in comparison to pure CS, the CS/HA/MMT composites exhibited improved hemocompatibility and protein adsorption. The sintering of the macrospheres controlled the swelling ability of the scaffolds which played an important role in maintaining the mechanical strength of the 3D scaffolds. The CS/HA/MMT composite scaffold showed 14 folds increase in the compressive strength when compared to pure CS scaffolds. The fabricated scaffolds were also found to encourage the MG 63 cell proliferation. Hence, from the above studies it can be concluded that the CS/HA/MMT composite 3D macrospheric scaffolds have wider and more practical application in bone tissue regeneration applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Black bears with longer disuse (hibernation) periods have lower femoral osteon population density and greater mineralization and intracortical porosity.

PubMed

Wojda, Samantha J; Weyland, David R; Gray, Sarah K; McGee-Lawrence, Meghan E; Drummer, Thomas D; Donahue, Seth W

2013-08-01

Intracortical bone remodeling is persistent throughout life, leading to age related increases in osteon population density (OPD). Intracortical porosity also increases with age in many mammals including humans, contributing to bone fragility and fracture risk. Unbalanced bone resorption and formation during disuse (e.g., physical inactivity) also increases intracortical porosity. In contrast, hibernating bears are a naturally occurring model for the prevention of both age-related and disuse osteoporoses. Intracortical bone remodeling is decreased during hibernation, but resorption and formation remain balanced. Black bears spend 0.25-7 months in hibernation annually depending on climate and food availability. We found longer hibernating bears demonstrate lower OPD and higher cortical bone mineralization than bears with shorter hibernation durations, but we surprisingly found longer hibernating bears had higher intracortical porosity. However, bears from three different latitudes showed age-related decreases in intracortical porosity, indicating that regardless of hibernation duration, black bears do not show the disuse- or age-related increases in intracortical porosity which is typical of other animals. This ability to prevent increases in intracortical porosity likely contributes to their ability to maintain bone strength during prolonged periods of physical inactivity and throughout life. Improving our understanding of the unique bone metabolism in hibernating bears will potentially increase our ability to develop treatments for age- and disuse-related osteoporoses in humans. Copyright © 2013 Wiley Periodicals, Inc.

Testing Pullout Strength of Pedicle Screw Using Synthetic Bone Models: Is a Bilayer Foam Model a Better Representation of Vertebra?

PubMed

Varghese, Vicky; Krishnan, Venkatesh; Saravana Kumar, Gurunathan

2018-06-01

A biomechanical study. A new biomechanical model of the vertebra has been developed that accounts for the inhomogeneity of bone and the contribution of the pedicle toward the holding strength of a pedicle screw. Pullout strength studies are typically carried out on rigid polyurethane foams that represent the homogeneous vertebral framework of the spine. However, the contribution of the pedicle region, which contributes to the inhomogeneity in this framework, has not been considered in previous investigations. Therefore, we propose a new biomechanical model that can account for the vertebral inhomogeneity, especially the contribution of the pedicles toward the pullout strength of the pedicle screw. A bilayer foam model was developed by joining two foams representing the pedicle and the vertebra. The results of the pullout strength tests performed on the foam models were compared with those from the tests performed on the cadaver lumbar vertebra. Significant differences ( p <0.05) were observed between the pullout strength of the pedicle screw in extremely osteoporotic (0.18±0.11 kN), osteoporotic (0.37±0.14 kN), and normal (0.97±0.4 kN) cadaver vertebra. In the monolayer model, significant differences ( p <0.05) were observed in pullout strength between extremely osteoporotic (0.3±0.02 kN), osteoporotic (0.65±0.12 kN), and normal (0.99±0.04 kN) bone model. However, the bilayer foam model exhibited no significant differences ( p >0.05) in the pullout strength of pedicle screws between osteoporotic (0.85±0.08 kN) and extremely osteoporotic bone models (0.94±0.08 kN), but there was a significant difference ( p <0.05) between osteoporotic (0.94±0.08 kN) and normal bone models (1.19±0.05 kN). There were no significant differences ( p >0.05) in pullout strength between cadaver and bilayer foam model in normal bones. The new synthetic bone model that reflects the contribution of the pedicles to the pullout strength of the pedicle screws could provide a more efficacious means of testing pedicle-screw pullout strength. The bilayer model can match the pullout strength value of normal lumbar vertebra bone whereas the monolayer foam model was able to match that of the extremely osteoporotic lumbar vertebra.

Strontium administration in young chickens improves bone volume and architecture but does not enhance bone structural and material strength.

PubMed

Shahnazari, M; Lang, D H; Fosmire, G J; Sharkey, N A; Mitchell, A D; Leach, R M

2007-03-01

Genetic selection for rapid body growth in broiler chickens has resulted in adverse effects on the skeletal system exemplified by a higher rate of cortical fractures in leg bones. Strontium (Sr) has been reported to have beneficial effects on bone formation and strength. We supplemented the diet of 300-day-old chicks with increasing dosages of Sr (0%, 0.12%, or 0.24%) to study the capacity of the element to improve bone quality and mechanical integrity. Treatment with Sr increased cortical bone volume and reduced bone porosity as measured by micro-computed tomography. The higher level of Sr significantly reduced bone Ca content (34.7%) relative to controls (37.2%), suggesting that Sr replaced some of the Ca in bone. Material properties determined by the three-point bending test showed that bone in the Sr-treated groups withstood greater deformation prior to fracture. Load to failure and ultimate stress were similar across groups. Our results indicate that Sr treatment in rapidly growing chickens induced positive effects on bone volume but did not improve the breaking strength of long bones.

Carbon nanotube, graphene and boron nitride nanotube reinforced bioactive ceramics for bone repair.

PubMed

Gao, Chengde; Feng, Pei; Peng, Shuping; Shuai, Cijun

2017-10-01

The high brittleness and low strength of bioactive ceramics have severely restricted their application in bone repair despite the fact that they have been regarded as one of the most promising biomaterials. In the last few years, low-dimensional nanomaterials (LDNs), including carbon nanotubes, graphene and boron nitride nanotubes, have gained increasing attention owing to their favorable biocompatibility, large surface specific area and super mechanical properties. These qualities make LDNs potential nanofillers in reinforcing bioactive ceramics. In this review, the types, characteristics and applications of the commonly used LDNs in ceramic composites are summarized. In addition, the fabrication methods for LDNs/ceramic composites, such as hot pressing, spark plasma sintering and selective laser sintering, are systematically reviewed and compared. Emphases are placed on how to obtain the uniform dispersion of LDNs in a ceramic matrix and maintain the structural stability of LDNs during the high-temperature fabrication process of ceramics. The reinforcing mechanisms of LDNs in ceramic composites are then discussed in-depth. The in vitro and in vivo studies of LDNs/ceramic in bone repair are also summarized and discussed. Finally, new developments and potential applications of LDNs/ceramic composites are further discussed with reference to experimental and theoretical studies. Despite bioactive ceramics having been regarded as promising biomaterials, their high brittleness and low strength severely restrict their application in bone scaffolds. In recent years, low-dimensional nanomaterials (LDNs), including carbon nanotubes, graphene and boron nitride nanotubes, have shown great potential in reinforcing bioactive ceramics owing to their unique structures and properties. However, so far it has been difficult to maintain the structural stability of LDNs during fabrication of LDNs/ceramic composites, due to the lengthy, high-temperature process involved. This review presents a comprehensive overview of the developments and applications of LDNs in bioactive ceramics. The newly-developed fabrication methods for LDNs/ceramic composites, the reinforcing mechanisms and the in vitro and in vivo performance of LDNs are also summarized and discussed in detail. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Associations of dietary patterns with bone mass, muscle strength and balance in a cohort of Australian middle-aged women.

PubMed

Wu, Feitong; Wills, Karen; Laslett, Laura L; Oldenburg, Brian; Jones, Graeme; Winzenberg, Tania

2017-10-01

Influences of dietary patterns on musculoskeletal health are poorly understood in middle-aged women. This cross-sectional analysis from a cohort of 347 women (aged 36-57 years) aimed to examine associations between dietary patterns and musculoskeletal health outcomes in middle-aged women. Diet was measured by the Cancer Council of Victoria FFQ. Total body bone mineral content (TB BMC), femoral neck and lumbar spine bone density (dual-energy X-ray absorptiometry), lower limbs muscle strength (LMS) and balance tests (timed up and go test, step test, functional reach test (FRT) and lateral reach test) were also measured. Exploratory factor analysis was used to identify dietary patterns and scores for each pattern generated using factor loadings with absolute values ≥0·20. Associations between food pattern scores and musculoskeletal outcomes were assessed using multivariable linear regression. Three dietary patterns were identified: 'Healthy' (high consumption of a plant-based diet - vegetables, legumes, fruit, tomatoes, nuts, snacks, garlic, whole grains and low intake of high-fat dairy products), 'high protein, high fat' (red meats, poultry, processed meats, potatoes, cruciferous and dark-yellow vegetables, fish, chips, spirits and high-fat dairy products) and 'Processed foods' (high intakes of meat pies, hamburgers, beer, sweets, fruit juice, processed meats, snacks, spirits, pizza and low intake of cruciferous vegetables). After adjustment for confounders, Healthy pattern was positively associated with LMS, whereas Processed foods pattern was inversely associated with TB BMC and FRT. The associations were not significant after accounting for multiple comparisons. There were no associations with any other outcomes. These results suggest that maintaining a healthy diet could contribute to bone acquisition, muscle strength and balance in adult life. However, while they provide some support for further investigating dietary strategies for prevention of age-related loss of muscle and deterioration in balance, the exploratory nature of the analyses means that confirmation in longitudinal studies and/or trials with pre-specified hypotheses is needed.

A study of the relationship between process conditions and mechanical strength of mineralized red algae in the preparation of a marine-derived bone void filler.

PubMed

Walsh, P J; Walker, G M; Maggs, C A; Buchanan, F J

2011-06-01

Bone void fillers that can enhance biological function to augment skeletal repair have significant therapeutic potential in bone replacement surgery. This work focuses on the development of a unique microporous (0.5-10 microm) marine-derived calcium phosphate bioceramic granule. It was prepared from Corallina officinalis, a mineralized red alga, using a novel manufacturing process. This involved thermal processing, followed by a low pressure-temperature chemical synthesis reaction. The study found that the ability to maintain the unique algal morphology was dependent on the thermal processing conditions. This study investigates the effect of thermal heat treatment on the physiochemical properties of the alga. Thermogravimetric analysis was used to monitor its thermal decomposition. The resultant thermograms indicated the presence of a residual organic phase at temperatures below 500 degrees C and an irreversible solid-state phase transition from mg-rich-calcite to calcium oxide at temperatures over 850 degrees C. Algae and synthetic calcite were evaluated following heat treatment in an air-circulating furnace at temperatures ranging from 400 to 800 degrees C. The highest levels of mass loss occurred between 400-500 degrees C and 700-800 degrees C, which were attributed to the organic and carbonate decomposition respectively. The changes in mechanical strength were quantified using a simple mechanical test, which measured the bulk compressive strength of the algae. The mechanical test used may provide a useful evaluation of the compressive properties of similar bone void fillers that are in granular form. The study concluded that soak temperatures in the range of 600 to 700 degrees C provided the optimum physiochemical properties as a precursor to conversion to hydroxyapatite (HA). At these temperatures, a partial phase transition to calcium oxide occurred and the original skeletal morphology of the alga remained intact.

Effects of combined elcatonin and alendronate treatment on the architecture and strength of bone in ovariectomized rats.

PubMed

Ogawa, Koko; Hori, Masayuki; Takao, Ryoko; Sakurada, Toyozo

2005-01-01

We examined the combined effects of elcatonin (ECT) and alendronate (ALN) on bone mass, architecture, and strength in ovariectomized (OVX) rats. Fifty female Sprague Dawley rats, aged 13 weeks, were divided into Sham, OVX, OVX+ECT, OVX+ALN, and OVX+ECT+ALN groups (n = 10). Immediately after ovariectomy, ECT was administered at a dose of 15 units (U)/kg three times a week, and ALN was administered daily at a dose of 2.0 microg/kg, subcutaneously for 12 weeks. The three-dimensional architecture of the bone in the distal femoral metaphysis was analyzed using a microfocus X-ray computed tomography system (microCT), and bone strength was measured using a material-testing machine. Trabecular bone volume (BV/TV) and number (Tb.N) were significantly greater in the OVX+ECT and OVX+ALN groups than in the OVX group. In the OVX+ECT+ALN group, BV/TV and Tb.N were significantly greater when compared with those in the OVX+ECT and OVX+ALN groups. Trabecular thickness (Tb.Th) was significantly greater in the OVX+ECT+ALN group than in the OVX+ALN group. With regard to bone strength, the compression strength in the femoral metaphysis was significantly lower in the OVX group than in the Sham group. The reduction of compression strength was slightly lower in the OVX+ECT and OVX+ALN groups. In the OVX+ECT+ALN group, the compression strength in the femoral metaphysis significantly increased when compared with the OVX and OVX+ECT groups. These results suggest that the combined treatment of ECT and ALN does not alter the individual effects of each drug and that it exerts an additive effect on trabecular architecture and bone strength in OVX rats.

Advanced Resistive Exercise Device

NASA Technical Reports Server (NTRS)

Raboin, Jasen; Niebuhr, Jason; Cruz, Santana; Lamoreaux, chris

2007-01-01

The advanced resistive exercise device (ARED), now at the prototype stage of development, is a versatile machine that can be used to perform different customized exercises for which, heretofore, it has been necessary to use different machines. Conceived as a means of helping astronauts and others to maintain muscle and bone strength and endurance in low-gravity environments, the ARED could also prove advantageous in terrestrial settings (e.g., health clubs and military training facilities) in which many users are exercising simultaneously and there is heavy demand for use of exercise machines.

Exercise-training protocols for astronauts in microgravity

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Bulbulian, R.; Bernauer, E. M.; Haskell, W. L.; Moore, T.

1989-01-01

Based on physical working requirements for astronauts during intra- and extravehicular activity and on the findings from bed-rest studies that utilized exercise training as a countermeasure for the reduction of aerobic power, deterioration of muscular strength and endurance, decrements in mood and cognitive performance, and possibly for bone loss, two exercise protocols are proposed. One assumes that, during microgravity, astronaut exercise physiological functions should be maintained at 100 percent of ground-based levels. The other assumes that maximal aerobic power in flight can be reduced by 10 percent of the ground-based level.

Strength training for children and adolescents.

PubMed

Faigenbaum, A D

2000-10-01

The potential benefits of youth strength training extend beyond an increase in muscular strength and may include favorable changes in selected health- and fitness-related measures. If appropriate training guidelines are followed, regular participation in a youth strength-training program has the potential to increase bone mineral density, improve motor performance skills, enhance sports performance, and better prepare our young athletes for the demands of practice and competition. Despite earlier concerns regarding the safety and efficacy of youth strength training, current public health objectives now aim to increase the number of boys and girls age 6 and older who regularly participate in physical activities that enhance and maintain muscular fitness. Parents, teachers, coaches, and healthcare providers should realize that youth strength training is a specialized method of conditioning that can offer enormous benefit but at the same time can result in serious injury if established guidelines are not followed. With qualified instruction, competent supervision, and an appropriate progression of the volume and intensity of training, children and adolescents cannot only learn advanced strength training exercises but can feel good about their performances, and have fun. Additional clinical trails involving children and adolescents are needed to further explore the acute and chronic effects of strength training on a variety of anatomical, physiological, and psychological parameters.

The effects of visceral obesity and androgens on bone: trenbolone protects against loss of femoral bone mineral density and structural strength in viscerally obese and testosterone-deficient male rats.

PubMed

Donner, D G; Elliott, G E; Beck, B R; Forwood, M R; Du Toit, E F

2016-03-01

In males, visceral obesity and androgen deficiency often present together and result in harmful effects on bone. Our findings show that both factors are independently associated with adverse effects on femoral bone structure and strength, and trenbolone protects rats from diet-induced visceral obesity and consequently normalises femoral bone structural strength. In light of the rapidly increasing incidence of obesity and osteoporosis globally, and recent conjecture regarding the effects of visceral adiposity and testosterone deficiency on bone health, we investigated the effects of increased visceral adipose tissue (VAT) mass on femoral bone mineral density (BMD), structure and strength in normal weight rats with testosterone deficiency. Male Wistar rats (n = 50) were fed either standard rat chow (CTRL, n = 10) or a high-fat/high-sugar diet (HF/HS, n = 40). Following 8 weeks of feeding, rats underwent sham surgery (CTRL, n = 10; HF/HS, n = 10) or orchiectomy (HF/HS + ORX, n = 30). Following a 4-week recovery period, mini-osmotic pumps containing either vehicle (CTRL, n = 10; HF/HS, n = 10; HF/HS + ORX, n = 10), 2.0 mg kg day(-1), testosterone (HF/HS + ORX + TEST, n = 10) or 2.0 mg kg day(-1) trenbolone (HF/HS + ORX + TREN, n = 10) were implanted for 8 weeks of treatment. Dual-energy X-ray absorptiometry and three-point bending tests were used to assess bone mass, structure and strength of femora. Diet-induced visceral obesity resulted in decreased bone mineral area (BMA) and content (BMC) and impaired femoral stiffness and strength. Orchiectomy further impaired BMA, BMC and BMD and reduced energy to failure in viscerally obese animals. Both TEST and TREN treatment restored BMA, BMC, BMD and energy to failure. Only TREN reduced visceral adiposity and improved femoral stiffness and strength. Findings support a role for both visceral adiposity and testosterone deficiency as independent risk factors for femoral osteoporosis, adverse bone geometry and impaired bone strength in male rats. Trenbolone may be a more effective candidate for androgen replacement therapy than testosterone in viscerally obese testosterone-deficient males.

The Effects of Annatto Tocotrienol on Bone Biomechanical Strength and Bone Calcium Content in an Animal Model of Osteoporosis Due to Testosterone Deficiency

PubMed Central

Chin, Kok-Yong; Gengatharan, Dhivakaran; Mohd Nasru, Fadlin Sakina; Khairussam, Rehan Amalia; Ern, Sherlyn Lai Hui; Aminuddin, Siti Aina Wahidah; Ima-Nirwana, Soelaiman

2016-01-01

Osteoporosis reduces the skeletal strength and increases the risk for fracture. It is an underdiagnosed disease in men. Annatto tocotrienol has been shown to improve bone structural indices and increase expression of bone formation genes in orchidectomized rats. This study aimed to evaluate the effects of annatto tocotrienol on biomechanical strength and calcium content of the bone in orchidectomized rats. Thirty three-month-old male Sprague-Dawley rats were randomly assigned to five groups. The baseline control (BC) group was sacrificed at the onset of the study. The sham-operated group (SHAM) received olive oil (the vehicle of tocotrienol) orally daily and peanut oil (the vehicle of testosterone) intramuscularly weekly. The remaining rats were orchidectomized and treated with three different regimens, i.e., (1) daily oral olive oil plus weekly intramuscular peanut oil injection; (2) daily oral annatto tocotrienol at 60 mg/kg plus weekly intramuscular peanut oil injection; (3) daily oral olive oil plus weekly intramuscular testosterone enanthate injection at 7 mg/kg. Blood, femur and tibia of the rats were harvested at the end of the two-month treatment period for the evaluation of serum total calcium and inorganic phosphate levels, bone biomechanical strength test and bone calcium content. Annatto-tocotrienol treatment improved serum calcium level and tibial calcium content (p < 0.05) but it did not affect femoral biomechanical strength (p > 0.05). In conclusion, annatto-tocotrienol at 60 mg/kg augments bone calcium level by preventing calcium mobilization into the circulation. A longer treatment period is needed for annatto tocotrienol to exert its effects on bone strength. PMID:27983628

VITAMIN C AND ZINC INTAKES ARE RELATED TO BONE MACRO-ARCHITECTURAL STRUCTURE AND STRENGTH IN PREPUBESCENT GIRLS

PubMed Central

Laudermilk, Monica J.; Manore, Melinda M.; Thomson, Cynthia A.; Houtkooper, Linda B.; Farr, Joshua N.; Going, Scott B.

2012-01-01

Background The extent to which nutrient intake may influence bone structure and strength during maximum rates of skeletal growth remains uncertain. Objective To examine the relationship of dietary intake of micronutrients and bone macro-architectural structure in young girls. Design This cross-sectional analysis included baseline data from 363 4th and 6th grade girls enrolled in the Jump-In study. Nutrient intake was assessed using the Harvard Youth/Adolescent Food Frequency Questionnaire. Volumetric BMD (vBMD), bone geometry and strength were measured by peripheral quantitative computed tomography (pQCT). Correlations and regression modeling assessed relations between usual nutrient intake and bone parameters. Results In 4th grade girls, metaphyseal and diaphyseal area and circumferences, and diaphyseal strength were associated with vitamin C intake (r = 0.15–0.19; p<0.05). Zinc intake was correlated with diaphyseal vBMD (r = 0.15–0.16; p<0.05). Using multiple linear regression to adjust for important covariates, we observed significant independent associations for vitamin C and zinc with bone parameters. For every mg/d of vitamin C intake trabecular area increased by 11%, cortical strength improved by 14%; and periosteal and endosteal circumferences increased by 5% and 8.6%, respectively. For every mg/d of zinc intake, cortical vBMD increased by <1%. No significant associations were observed in 6th-grade girls. Conclusion Results of this study suggests that vitamin C and zinc intake are positively associated with objective measures of bone geometry, size and strength in 4th-grade girls. This indicates potential differences in micronutrient and bone associations at various age-associated stages of bone maturation perhaps indicative of competing hormonal influences. PMID:23076447

The Effects of Annatto Tocotrienol on Bone Biomechanical Strength and Bone Calcium Content in an Animal Model of Osteoporosis Due to Testosterone Deficiency.

PubMed

Chin, Kok-Yong; Gengatharan, Dhivakaran; Mohd Nasru, Fadlin Sakina; Khairussam, Rehan Amalia; Ern, Sherlyn Lai Hui; Aminuddin, Siti Aina Wahidah; Ima-Nirwana, Soelaiman

2016-12-14

Osteoporosis reduces the skeletal strength and increases the risk for fracture. It is an underdiagnosed disease in men. Annatto tocotrienol has been shown to improve bone structural indices and increase expression of bone formation genes in orchidectomized rats. This study aimed to evaluate the effects of annatto tocotrienol on biomechanical strength and calcium content of the bone in orchidectomized rats. Thirty three-month-old male Sprague-Dawley rats were randomly assigned to five groups. The baseline control (BC) group was sacrificed at the onset of the study. The sham-operated group (SHAM) received olive oil (the vehicle of tocotrienol) orally daily and peanut oil (the vehicle of testosterone) intramuscularly weekly. The remaining rats were orchidectomized and treated with three different regimens, i.e., (1) daily oral olive oil plus weekly intramuscular peanut oil injection; (2) daily oral annatto tocotrienol at 60 mg/kg plus weekly intramuscular peanut oil injection; (3) daily oral olive oil plus weekly intramuscular testosterone enanthate injection at 7 mg/kg. Blood, femur and tibia of the rats were harvested at the end of the two-month treatment period for the evaluation of serum total calcium and inorganic phosphate levels, bone biomechanical strength test and bone calcium content. Annatto-tocotrienol treatment improved serum calcium level and tibial calcium content ( p < 0.05) but it did not affect femoral biomechanical strength ( p > 0.05). In conclusion, annatto-tocotrienol at 60 mg/kg augments bone calcium level by preventing calcium mobilization into the circulation. A longer treatment period is needed for annatto tocotrienol to exert its effects on bone strength.

Enhanced tendon-to-bone repair through adhesive films.

PubMed

Linderman, Stephen W; Golman, Mikhail; Gardner, Thomas R; Birman, Victor; Levine, William N; Genin, Guy M; Thomopoulos, Stavros

2018-04-01

Tendon-to-bone surgical repairs have unacceptably high failure rates, possibly due to their inability to recreate the load transfer mechanisms of the native enthesis. Instead of distributing load across a wide attachment footprint area, surgical repairs concentrate shear stress on a small number of suture anchor points. This motivates development of technologies that distribute shear stresses away from suture anchors and across the enthesis footprint. Here, we present predictions and proof-of-concept experiments showing that mechanically-optimized adhesive films can mimic the natural load transfer mechanisms of the healthy attachment and increase the load tolerance of a repair. Mechanical optimization, based upon a shear lag model corroborated by a finite element analysis, revealed that adhesives with relatively high strength and low stiffness can, theoretically, strengthen tendon-to-bone repairs by over 10-fold. Lap shear testing using tendon and bone planks validated the mechanical models for a range of adhesive stiffnesses and strengths. Ex vivo human supraspinatus repairs of cadaveric tissues using multipartite adhesives showed substantial increase in strength. Results suggest that adhesive-enhanced repair can improve repair strength, and motivate a search for optimal adhesives. Current surgical techniques for tendon-to-bone repair have unacceptably high failure rates, indicating that the initial repair strength is insufficient to prevent gapping or rupture. In the rotator cuff, repair techniques apply compression over the repair interface to achieve contact healing between tendon and bone, but transfer almost all force in shear across only a few points where sutures puncture the tendon. Therefore, we evaluated the ability of an adhesive film, implanted between tendon and bone, to enhance repair strength and minimize the likelihood of rupture. Mechanical models demonstrated that optimally designed adhesives would improve repair strength by over 10-fold. Experiments using idealized and clinically-relevant repairs validated these models. This work demonstrates an opportunity to dramatically improve tendon-to-bone repair strength using adhesive films with appropriate material properties. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Percutaneous osteoplasty with a bone marrow nail for fractures of long bones: experimental study.

PubMed

Nakata, Kouhei; Kawai, Nobuyuki; Sato, Morio; Cao, Guang; Sahara, Shinya; Tanihata, Hirohiko; Takasaka, Isao; Minamiguchi, Hiroyuki; Nakai, Tomoki

2010-09-01

To develop percutaneous osteoplasty with the use of a bone marrow nail for fixation of long-bone fractures, and to evaluate its feasibility and safety in vivo and in vitro. Six long bones in three healthy swine were used in the in vivo study. Acrylic cement was injected through an 11-gauge bone biopsy needle and a catheter into a covered metallic stent placed within the long bone, creating a bone marrow nail. In the in vitro study, we determined the bending, tug, and compression strengths of the acrylic cement nails 9 cm long and 8 mm in diameter (N = 10). The bending strength of the artificially fractured bones (N = 6) restored with the bone marrow nail and cement augmentation was then compared with that of normal long bones (N = 6). Percutaneous osteoplasty with a bone marrow nail was successfully achieved within 1 hour for all swine. After osteoplasty, all swine regained the ability to run until they were euthanized. Blood tests and pathologic findings showed no adverse effects. The mean bending, tug, and compression strengths of the nail were 91.4 N/mm(2) (range, 75.0-114.1 N/mm(2)), 20.9 N/mm(2) (range, 6.6-30.4 N/mm(2)), and 103.0 N/mm(2) (range, 96.3-110.0 N/mm(2)), respectively. The bending strength ratio of artificially fractured bones restored with bone marrow nail and cement augmentation to normal long bone was 0.32. Percutaneous osteoplasty with use of a bone marrow nail and cement augmentation appears to have potential in treating fractures of non-weight-bearing long bones. Copyright 2010 SIR. Published by Elsevier Inc. All rights reserved.

Transcutaneous Raman Spectroscopy of Bone

NASA Astrophysics Data System (ADS)

Maher, Jason R.

Clinical diagnoses of bone health and fracture risk typically rely upon measurements of bone density or structure, but the strength of a bone is also dependent upon its chemical composition. One technology that has been used extensively in ex vivo, exposed-bone studies to measure the chemical composition of bone is Raman spectroscopy. This spectroscopic technique provides chemical information about a sample by probing its molecular vibrations. In the case of bone tissue, Raman spectra provide chemical information about both the inorganic mineral and organic matrix components, which each contribute to bone strength. To explore the relationship between bone strength and chemical composition, our laboratory has contributed to ex vivo, exposed-bone animal studies of rheumatoid arthritis, glucocorticoid-induced osteoporosis, and prolonged lead exposure. All of these studies suggest that Raman-based predictions of biomechanical strength may be more accurate than those produced by the clinically-used parameter of bone mineral density. The utility of Raman spectroscopy in ex vivo, exposed-bone studies has inspired attempts to perform bone spectroscopy transcutaneously. Although the results are promising, further advancements are necessary to make non-invasive, in vivo measurements of bone that are of sufficient quality to generate accurate predictions of fracture risk. In order to separate the signals from bone and soft tissue that contribute to a transcutaneous measurement, we developed an overconstrained extraction algorithm that is based upon fitting with spectral libraries derived from separately-acquired measurements of the underlying tissue components. This approach allows for accurate spectral unmixing despite the fact that similar chemical components (e.g., type I collagen) are present in both soft tissue and bone and was applied to experimental data in order to transcutaneously detect, to our knowledge for the first time, age- and disease-related spectral differences in murine bone.

Determinants of the mechanical properties of bones

NASA Technical Reports Server (NTRS)

Martin, R. B.

1991-01-01

The mechanical properties of bones are governed by the same principles as those of man-made load-bearing structures, but the organism is able to adapt its bone structure to changes in skeletal loading. In this overview of the determinants of the strength and stiffness of bone, a continuum approach has been taken, in which the behavior of a macroscopic structure depends on its shape and size, and on the mechanical properties of the material within. The latter are assumed to depend on the composition (porosity and mineralization) and organization (trabecular or cortical bone architecture, collagen fiber orientation, fatigue damage) of the bone. The effects of each of these factors are reviewed. Also, the possible means of non-invasively estimating the strength or other mechanical properties of a bone are reviewed, including quantitative computed tomography, photon absorptiometry, and ultrasonic measurements. The best estimates of strength have been obtained with photon absorptiometry and computed tomography, which at best are capable of accounting for 90% of the strength variability in a simple in vitro test, but results from different laboratories have been highly variable.

An experimental study to investigate biomechanical aspects of the initial stability of press-fit implants.

PubMed

Berahmani, Sanaz; Janssen, Dennis; van Kessel, Sal; Wolfson, David; de Waal Malefijt, Maarten; Buma, Pieter; Verdonschot, Nico

2015-02-01

Initial fixation of press-fit implants depends on interference fit, surface morphology, and bone material properties. To understand the biomechanical effect of each factor and their interactions, the pull-out strength of seven types of CoCrMo tapered implants, with four different interference fits, three different surface morphologies (low, medium and high roughness), and at two time points (0 and 30 min) were tested in trabecular bone with varying density. The effect of interference fit on pull-out strength depended on the surface morphology and time. In contrast with our expectations, samples with a higher roughness had a lower pull-out strength. We found a similar magnitude of bone damage for the different surface morphologies, but the type of damage was different, with bone compaction versus bone abrasion for low and high frictional surfaces, respectively. This explains a reduced sensitivity of fixation strength to bone mineral density in the latter group. In addition, a reduction in fixation strength after a waiting period only occurred for the low frictional specimens. Our study demonstrates that it is essential to evaluate the interplay between different factors and emphasizes the importance of testing in natural bone in order to optimize the initial stability of press-fit implants. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mechanical degradation of porous titanium with entangled structure filled with biodegradable magnesium in Hanks' solution.

PubMed

Li, Qiuyan; Jiang, Guofeng; Wang, Cunlong; Dong, Jie; He, Guo

2015-12-01

The degradation behavior of the porous titanium with entangled structure filled with biodegradable magnesium (p-Ti/Mg) in Hanks' solution was investigated. It was found that the p-Ti/Mg composite had higher strength than pure magnesium and porous titanium with entangled structure (p-Ti). Although the magnesium in p-Ti/Mg was completely dissolved in Hanks' solution after immersion for 104 h, the rest of the sample still maintained strength of about 86 MPa. Moreover, the produced porousness (due to magnesium-degradation) could provide channels for the ingrowth and transportation of bone cells. However, the high corrosion rate of p-Ti/Mg is still a problem when used as a candidate biomedical material, which needs further improvement. Copyright © 2015 Elsevier B.V. All rights reserved.

Influence of bolt tightening torque, wire size, and component reuse on wire fixation in circular external fixation.

PubMed

Wosar, Marc A; Marcellin-Little, Denis J; Roe, Simon C

2002-01-01

To evaluate the effects of bolt torque, wire size, and component reuse on the ability to maintain wire tension in 3 external skeletal fixation systems. Biomechanical study. Yield strength in tension of 1.0-, 1.2-, 1.5-, and 1.6-mm-diameter wires, and yield strength in torque of Hofmann Small Bone Fixation (SBF) cannulated and slotted bolts and IMEX regular and miniature bolts were determined on a testing machine. The minimum bolt tightening torque needed to prevent wire slippage at clinically recommended wire tensions was determined. Components were tested 10 times, and loads at slippage were recorded. The IMEX system required a mean of 8 Nm of bolt tightening torque to maintain 900 N (1.6-mm wires). The SBF system required a mean of 3 Nm bolt torque to maintain 300 N (1.0-mm wires) and 5 Nm to maintain 600 N (1.2-mm wires). The SBF cannulated bolt required 9 Nm of torque to maintain 900 N (1.5-mm wires). The SBF slotted bolts could only maintain 800 N before yield. The IMEX miniature system required a mean bolt torque of 1.1 Nm to maintain 300 N. The cannulated and slotted bolts from both manufacturers failed to maintain 70% of initial wire tension after 7 and 4 uses, respectively. The IMEX systems and the SBF system using 1.0- and 1.2-mm wires could maintain clinically recommended wire tension safely. Only the IMEX system could maintain clinically recommended wire tension safely using 1.5- or 1.6-mm wires. The SBF system using 1.0- and 1.2-mm wires and the IMEX system using all wire sizes can maintain clinically relevant wire tension. The SBF system using 1.5-mm wires could not. Cannulated and slotted bolts should not be used more than 6 and 3 times, respectively. Nuts should not be reused. Copyright 2002 by The American College of Veterinary Surgeons

Genetic perturbations that impair functional trait interactions lead to reduced bone strength and increased fragility in mice

PubMed Central

Smith, Lauren M.; Bigelow, Erin M.R.; Nolan, Bonnie T.; Faillace, Meghan E.; Nadeau, Joseph H.; Jepsen, Karl J.

2014-01-01

Functional adaptation may complicate the choice of phenotype used in genetic studies that seek to identify genes contributing to fracture susceptibility. Often, genetic variants affecting one trait are compensated by coordinated changes in other traits. Bone fracture is a prototypic example because mechanical function of long bones (stiffness and strength) depends on how the system coordinately adjusts the amount (cortical area) and quality (tissue-mineral density, TMD) of bone tissue to mechanically offset the natural variation in bone robustness (total area/length). We propose that efforts aimed at identifying genes regulating fracture resistance will benefit from better understanding how functional adaptation contributes to the genotype-phenotype relationship. We analyzed the femurs of C57BL/6J – ChrA/J/NaJ Chromosome Substitution Strains (CSSs) to systemically interrogate the mouse genome for chromosomes harboring genes that regulate mechanical function. These CSSs (CSS-i, i = the substituted chromosome) showed changes in mechanical function on the order of -26.6 to 11.5% relative to the B6 reference strain after adjusting for body size. Seven substitutions showed altered robustness, cortical area, or TMD, but no effect on mechanical function (CSS-4, 5, 8, 9, 17, 18, 19); six substitutions showed altered robustness, cortical area, or TMD, and reduced mechanical function (CSS-1, 2, 6, 10, 12, 15); and one substitution also showed reduced mechanical function but exhibited no significant changes in the three physical traits analyzed in this study (CSS-3). A key feature that distinguished CSSs that maintained function from those with reduced function was whether the system adjusted cortical area and TMD to the levels needed to compensate for the natural variation in bone robustness. These results provide a novel biomechanical mechanism linking genotype with phenotype, indicating that genes control function not only by regulating individual traits, but also by regulating how the system coordinately adjusts multiple traits to establish function. PMID:25003813

Mapping the natural variation in whole bone stiffness and strength across skeletal sites.

PubMed

Schlecht, Stephen H; Bigelow, Erin M R; Jepsen, Karl J

2014-10-01

Traits of the skeletal system are coordinately adjusted to establish mechanical homeostasis in response to genetic and environmental factors. Prior work demonstrated that this 'complex adaptive' process is not perfect, revealing a two-fold difference in whole bone stiffness of the tibia across a population. Robustness (specifically, total cross-sectional area relative to length) varies widely across skeletal sites and between sexes. However, it is unknown whether the natural variation in whole bone stiffness and strength also varies across skeletal sites and between men and women. We tested the hypotheses that: 1) all major long bones of the appendicular skeleton demonstrate inherent, systemic constraints in the degree to which morphological and compositional traits can be adjusted for a given robustness; and 2) these traits covary in a predictable manner independent of body size and robustness. We assessed the functional relationships among robustness, cortical area (Ct.Ar), cortical tissue mineral density (Ct.TMD), and bone strength index (BSI) across the long bones of the upper and lower limbs of 115 adult men and women. All bones showed a significant (p<0.001) positive regression between BSI and robustness after adjusting for body size, with slender bones being 1.7-2.3 times less stiff and strong in men and 1.3-2.8 times less stiff and strong in women compared to robust bones. Our findings are the first to document the natural inter-individual variation in whole bone stiffness and strength that exist within populations and that is predictable based on skeletal robustness for all major long bones. Documenting and further understanding this natural variation in strength may be critical for differentially diagnosing and treating skeletal fragility. Copyright © 2014 Elsevier Inc. All rights reserved.

Mapping the natural variation in whole bone stiffness and strength across skeletal sites

PubMed Central

Schlecht, Stephen H.; Bigelow, Erin M.R.; Jepsen, Karl J.

2016-01-01

Traits of the skeletal system are coordinately adjusted to establish mechanical homeostasis in response to genetic and environmental factors. Prior work demonstrated that this `complex adaptive' process is not perfect, revealing a two-fold difference in whole bone stiffness of the tibia across a population. Robustness (specifically, total cross-sectional area relative to length) varies widely across skeletal sites and between sexes. However, it is unknown whether the natural variation in whole bone stiffness and strength also varies across skeletal sites and between men and women. We tested the hypotheses that: 1) all major long bones of the appendicular skeleton demonstrate inherent, systemic constraints in the degree to which morphological and compositional traits can be adjusted for a given robustness; and 2) these traits covary in a predictable manner independent of body size and robustness. We assessed the functional relationships among robustness, cortical area (Ct.Ar), cortical tissue mineral density (Ct.TMD), and bone strength index (BSI) across the long bones of the upper and lower limbs of 115 adult men and women. All bones showed a significant (p < 0.001) positive regression between BSI and robustness after adjusting for body size, with slender bones being 1.7–2.3 times less stiff and strong in men and 1.3–2.8 times less stiff and strong in women compared to robust bones. Our findings are the first to document the natural inter-individual variation in whole bone stiffness and strength that exist within populations and that is predictable based on skeletal robustness for all major long bones. Documenting and further understanding this natural variation in strength may be critical for differentially diagnosing and treating skeletal fragility. PMID:24999223

Shock wave treatment shows dose-dependent enhancement of bone mass and bone strength after fracture of the femur.

PubMed

Wang, Ching-Jen; Yang, Kuender D; Wang, Feng-Sheng; Hsu, Chia-Chen; Chen, Hsiang-Ho

2004-01-01

Shock wave treatment is believed to improve bone healing after fracture. The purpose of this study was to evaluate the effect of shock wave treatment on bone mass and bone strength after fracture of the femur in a rabbit model. A standardized closed fracture of the right femur was created with a three-point bending method in 24 New Zealand white rabbits. Animals were randomly divided into three groups: (1) control (no shock wave treatment), (2) low-energy (shock wave treatment at 0.18 mJ/mm2 energy flux density with 2000 impulses), and (3) high-energy (shock wave treatment at 0.47 mJ/mm2 energy flux density with 4000 impulses). Bone mass (bone mineral density (BMD), callus formation, ash and calcium contents) and bone strength (peak load, peak stress and modulus of elasticity) were assessed at 12 and 24 weeks after shock wave treatment. While the BMD values of the high-energy group were significantly higher than the control group (P = 0.021), the BMD values between the low-energy and control groups were not statistically significant (P = 0.358). The high-energy group showed significantly more callus formation (P < 0.001), higher ash content (P < 0.001) and calcium content (P = 0.003) than the control and low-energy groups. With regard to bone strength, the high-energy group showed significantly higher peak load (P = 0.012), peak stress (P = 0.015) and modulus of elasticity (P = 0.011) than the low-energy and control groups. Overall, the effect of shock wave treatment on bone mass and bone strength appears to be dose dependent in acute fracture healing in rabbits.

Effects of an 8-Month Ashtanga-Based Yoga Intervention on Bone Metabolism in Middle-Aged Premenopausal Women: A Randomized Controlled Study

PubMed Central

Kim, SoJung; Bemben, Michael G.; Knehans, Allen W.; Bemben, Debra A.

2015-01-01

Although Yoga has the potential to be an alternative physical activity to enhance bone health, there is a lack of high quality evidence for this type of intervention. The purpose of this randomized controlled trial was to examine the effects of a progressive 8-month Ashtanga-based Yoga program on bone turnover markers (BTM), areal bone mineral density (aBMD) and volumetric bone characteristics in premenopausal women. Thirty-four premenopausal women (35-50 years) were randomly assigned either to a Yoga group (YE, n = 16) or a control group (CON, n = 18). Participants in YE group performed 60 minutes of an Ashtanga-based Yoga series 2 times/week with one day between sessions for 8 months, and the session intensity was progressively increased by adding the number of sun salutations (SS). Participants in CON were encouraged to maintain their normal daily lifestyles monitored by the bone specific physical activity questionnaire (BPAQ) at 2 month intervals for 8 months. Body composition was measured by dual energy x-ray absorptiometry (DXA). Bone formation (bone alkaline phosphatase, Bone ALP) and bone resorption (Tartrate-Resistant Acid Phosphatase-5b, TRAP5b) markers were assessed at baseline and after 8 months. aBMD of total body, lumbar spine and dual proximal femur and tibia bone characteristics were measured using DXA and peripheral Quantitative Computed Tomography (pQCT), respectively. We found that the serum Bone ALP concentrations were maintained in YE, but significantly (p = 0.005) decreased in CON after the 8 month intervention, and there were significant (p = 0.002) group differences in Bone ALP percent changes (YE 9.1 ± 4.0% vs. CON -7.1 ± 2.3%). No changes in TRAP5b were found in either group. The 8-month Yoga program did not increase aBMD or tibia bone strength variables. Body composition results showed no changes in weight, fat mass, or % fat, but small significant increases in bone free lean body mass occurred in both groups. The findings of this study suggest that regular long-term Ashtanga Yoga had a small positive effect on bone formation but did not alter aBMD or tibia bone characteristics in premenopausal women. Key points Regular long-term Ashtanga-based Yoga program had a small positive effect on bone formation, but no effects were found on bone resorption. None of the bone density or geometry variables were changed by the 8-month Ashtanga-based Yoga intervention. Future Yoga interventions should focus on longer duration and greater frequency to elicit improvements in bone mineral density. PMID:26664272

Considerations for an exercise prescription

NASA Technical Reports Server (NTRS)

Convertino, Victor A.

1989-01-01

A number of past and most recent research findings that describe some of the physiological responses to exercise in man and their relationship with exposure to various gravitational environments are discussed. Most of the data pertain to adaptations of the cardiovascular and body fluid systems. It should be kept in mind that the data from studies on microgravity simulation in man include exposures of relatively short duration (5 hours to 14 days). However, it is argued that the results may provide important guidelines for the consideration of many variables which are pertinent to the development of exercise prescription for long-duration space flight. The following considerations for exercise prescriptions during long-duration space flight are noted: (1) Relatively high aerobic fitness and strength, especially of the upper body musculature, should be a criterion for selection of astronauts who will be involved in EVA, since endurance and strength appear to be predominant characteristics for work performance. (2) Some degree of upper body strength will probably be required for effective performance of EVA. However, the endurance and strength required by the upper body for EVA can probably be obtained through preflight exercise prescription which involves swimming. (3) Although some degree of arm exercise may be required to maintain preflight endurance and strength, researchers propose that regular EVA will probably be sufficient to maintain the endurance and strength required to effectively perform work tasks during space flight. (4) A minimum of one maximal aerobic exercise every 7 to 10 days during space flight may be all that is necessary for maintenance of normal cardiovascular responsiveness and replacement of body fluids for reentry following prolonged space flight. (5) The possible reduction in the amount of exercise required for maintenance of cardiovascular system and body fluids in combination with the use of electromyostimulation (EMS) or methods other than conventional exercise for maintaining size and strength of muscles and bones needs great consideration for further research. These approaches represent a potential solution to the problem of compromising valuable time for exercise that is needed for daily operations.

Tensile behavior of porous scaffolds made from poly(para phenylene) - biomed 2013.

PubMed

Dirienzo, Amy L; Yakacki, Christopher M; Safranski, David L; Frick, Carl P

2013-01-01

The goal of this study was to fabricate and mechanically characterize a high-strength porous polymer scaffold for potential use as an orthopedic device. Poly(para-phenylene) (PPP) is an excellent candidate due to its exceptional strength and stiffness and relative inertness, but has never been explicitly investigated for use as a biomedical device. PPP has strength values 3 to 10 times higher and an elastic modulus nearly an order of magnitude higher than traditional polymers such as poly(methyl methacrylate) (PMMA), polycaprolactone (PCL), ultra-high molecular weight polyethylene (UHMWPE), and polyurethane (PU) and is significantly stronger and stiffer than polyetheretherketone (PEEK). By utilizing PPP we can overcome the mechanical limitations of traditional porous polymeric scaffolds since the outstanding stiffness of PPP allows for a highly porous structure appropriate for osteointegration that can match the stiffness of bone (100-250 MPa), while maintaining suitable mechanical properties for soft-tissue fixation. Porous samples were manufactured by powder sintering followed by particle leaching. The pore volume fraction was systematically varied from 50–80 vol% for a pore sizes from150-500 µm, as indicated by previous studies for optimal osteointegration. The tensile modulus of the porous samples was compared to the rule of mixtures, and closely matches foam theory up to 70 vol%. The experimental modulus for 70 vol% porous samples matches the stiffness of bone and contains pore sizes optimal for osteointegration.

Low load, high repetition resistance training program increases bone mineral density in untrained adults.

PubMed

Petersen, Bailey A; Hastings, Bryce; Gottschall, Jinger S

2017-01-01

High load, low repetition resistance training increases BMD in untrained adults; however, many older and untrained adults cannot maintain this type of strenuous program. Our goal was to evaluate whether a low load, high repetition resistance training program would increase BMD in untrained adults. Twenty sedentary, but otherwise healthy, adults (6 men and 14 women, age 28-63 yrs) completed a 27-week group exercise program. The participants were randomly assigned to one of two strength groups: one group completed full body, low load, high repetition weight training classes (S-WEIGHT), while the other group completed core focused fusion classes (S-CORE). Both groups also completed indoor cycling classes for cardiovascular conditioning. After a 3-week familiarization period, all participants completed a 12-week block of 5 fitness classes per week (3 cycling + 2 strength) and concluded with another 12-week block of 6 classes per week (3 cycling + 3 strength). We completed iDXA scans at baseline (week 3) and final (week 28). Compared to baseline, BMD significantly increased for S-WEIGHT in the arms (+4%, P<0.001), legs (+8%, P<0.01), pelvis (+6%, P<0.01) and lumbar spine (+4%, P<0.05), whereas BMD did not significantly change for S-CORE at any site. These results suggest that a low load, high repetition resistance training program may be an effective method to improve bone mass in adults.

Finite Element Analysis of Denosumab Treatment Effects on Vertebral Strength in Ovariectomized Cynomolgus Monkeys.

PubMed

Lee, David C; Varela, Aurore; Kostenuik, Paul J; Ominsky, Michael S; Keaveny, Tony M

2016-08-01

Finite element analysis has not yet been validated for measuring changes in whole-bone strength at the hip or spine in people after treatment with an osteoporosis agent. Toward that end, we assessed the ability of a clinically approved implementation of finite element analysis to correctly quantify treatment effects on vertebral strength, comparing against direct mechanical testing, in cynomolgus monkeys randomly assigned to one of three 16-month-long treatments: sham surgery with vehicle (Sham-Vehicle), ovariectomy with vehicle (OVX-Vehicle), or ovariectomy with denosumab (OVX-DMAb). After treatment, T12 vertebrae were retrieved, scanned with micro-CT, and mechanically tested to measure compressive strength. Blinded to the strength data and treatment codes, the micro-CT images were coarsened and homogenized to create continuum-type finite element models, without explicit porosity. With clinical translation in mind, these models were then analyzed for strength using the U.S. Food and Drug Administration (FDA)-cleared VirtuOst software application (O.N. Diagnostics, Berkeley, CA, USA), developed for analysis of human bones. We found that vertebral strength by finite element analysis was highly correlated (R(2)  = 0.97; n = 52) with mechanical testing, independent of treatment (p = 0.12). Further, the size of the treatment effect on strength (ratio of mean OVX-DMAb to mean OVX-Vehicle, as a percentage) was large and did not differ (p = 0.79) between mechanical testing (+57%; 95% CI [26%, 95%]) and finite element analysis (+51% [20%, 88%]). The micro-CT analysis revealed increases in cortical thickness (+45% [19%, 73%]) and trabecular bone volume fraction (+24% [8%, 42%]). These results show that a preestablished clinical finite element analysis implementation-developed for human bone and clinically validated in fracture-outcome studies-correctly quantified the observed treatment effects of denosumab on vertebral strength in cynomolgus monkeys. One implication is that the treatment effects in this study are well explained by the features contained within these finite element models, namely, the bone geometry and mass and the spatial distribution of bone mass. © 2016 American Society for Bone and Mineral Research. © 2016 American Society for Bone and Mineral Research.

The effects of simulated bone loss on the implant-abutment assembly and likelihood of fracture: an in vitro study.

PubMed

Manzoor, Behzad; Suleiman, Mahmood; Palmer, Richard M

2013-01-01

The crestal bone level around a dental implant may influence its strength characteristics by offering protection against mechanical failures. Therefore, the present study investigated the effect of simulated bone loss on modes, loads, and cycles to failure in an in vitro model. Different amounts of bone loss were simulated: 0, 1.5, 3.0, and 4.5 mm from the implant head. Forty narrow-diameter (3.0-mm) implant-abutment assemblies were tested using compressive bending and cyclic fatigue testing. Weibull and accelerated life testing analysis were used to assess reliability and functional life. Statistical analyses were performed using the Fisher-Exact test and the Spearman ranked correlation. Compressive bending tests showed that the level of bone loss influenced the load-bearing capacity of implant-abutment assemblies. Fatigue testing showed that the modes, loads, and cycles to failure had a statistically significant relationship with the level of bone loss. All 16 samples with bone loss of 3.0 mm or more experienced horizontal implant body fractures. In contrast, 14 of 16 samples with 0 and 1.5 mm of bone loss showed abutment and screw fractures. Weibull and accelerated life testing analysis indicated a two-group distribution: the 0- and 1.5-mm bone loss samples had better functional life and reliability than the 3.0- and 4.5-mm samples. Progressive bone loss had a significant effect on modes, loads, and cycles to failure. In addition, bone loss influenced the functional life and reliability of the implant-abutment assemblies. Maintaining crestal bone levels is important in ensuring biomechanical sustainability and predictable long-term function of dental implant assemblies.

Precision of pQCT-measured total, trabecular and cortical bone area, content, density and estimated bone strength in children

PubMed Central

Duff, W.R.D.; Björkman, K.M.; Kawalilak, C.E.; Kehrig, A.M.; Wiebe, S.; Kontulainen, S.

2017-01-01

Objectives: To define pQCT precision errors, least-significant-changes, and identify associated factors for bone outcomes at the radius and tibia in children. Methods: We obtained duplicate radius and tibia pQCT scans from 35 children (8-14yrs). We report root-mean-squared coefficient of variation (CV%RMS) and 95% limits-of-agreement to characterize repeatability across scan quality and least-significant-changes for bone outcomes at distal (total and trabecular area, content and density; and compressive bone strength) and shaft sites (total area and content; cortical area content, density and thickness; and torsional bone strength). We used Spearman’s rho to identify associations between CV% and time between measurements, child’s age or anthropometrics. Results: After excluding unanalyzable scans (6-10% of scans per bone site), CV%RMS ranged from 4% (total density) to 19% (trabecular content) at the distal radius, 4% (cortical content) to 8% (cortical thickness) at the radius shaft, 2% (total density) to 14% (trabecular content) at the distal tibia and from 2% (cortical content) to 6% (bone strength) at the tibia shaft. Precision errors were within 95% limits-of-agreement across scan quality. Age was associated (rho -0.4 to -0.5, p <0.05) with CV% at the tibia. Conclusion: Bone density outcomes and cortical bone properties appeared most precise (CV%RMS <5%) in children. PMID:28574412

Effect of various factors on pull out strength of pedicle screw in normal and osteoporotic cancellous bone models.

PubMed

Varghese, Vicky; Saravana Kumar, Gurunathan; Krishnan, Venkatesh

2017-02-01

Pedicle screws are widely used for the treatment of spinal instability by spine fusion. Screw loosening is a major problem of spine fusion, contributing to delayed patient recovery. The present study aimed to understand the factor and interaction effects of density, insertion depth and insertion angle on pedicle screw pull out strength and insertion torque. A pull out study was carried out on rigid polyurethane foam blocks representing osteoporotic to normal bone densities according to the ASTM-1839 standard. It was found that density contributes most to pullout strength and insertion torque. The interaction effect is significant (p < 0.05) and contributes 8% to pull out strength. Axial pullout strength was 34% lower than angled pull out strength in the osteoporotic bone model. Insertion angle had no significant effect (p > 0.05) on insertion torque. Pullout strength and insertion torque had no significant correlation (p > 0.05) in the case of the extremely osteoporotic bone model. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

Integrating micro CT indices, CT imaging and computational modelling to assess the mechanical performance of fluoride treated bone.

PubMed

Sreenivasan, D; Watson, M; Callon, K; Dray, M; Das, R; Grey, A; Cornish, J; Fernandez, J

2013-12-01

In this study we evaluate the influence of low-dose fluoride treatment on 23 patient biopsies. Computational finite element (FE) models of each biopsy were subjected to a range of loads including compression, shear and torsion. The modelling framework was validated against three 3D printed models with known material properties subjected to compression till failure using an Instron machine. The primary outcomes from this study were that mechanical strength was not significantly correlated to low-dose (<10 mg/day) of fluoride levels (one-way ANOVA, P-values of 0.78, 0.69 and 0.62 for compression, shear and torsion, respectively). However, when bulk bone material properties were derived from DXA bone mineral density (BMD) from each patient's proximal femur a non-significant linear decline in mechanical strength with increase in fluoride was predicted. When the same material property was used for all bones (to evaluate bone architecture influence) then mechanical strength showed a characteristic concave upwards trend, consistent with the variation of micro CT derived percentage bone volume (BV/TV). The secondary outcomes from this study were that in compression, BV/TV was observed to be a strong surrogate measure for mechanical strength (R(2) = 0.83), while bone surface density (R(2)=0.6), trabecular thickness (R(2) = 0.5) and intersection surface (R(2) = 0.6) also explained the variation of mechanical strength well. However, trabecular separation and trabecular number were mildly correlated with mechanical strength (R(2) of 0.31 and 0.35, respectively). Compression was the loading mode most strongly correlated to micro CT indices. Material properties adapted from the proximal femur reduced the CT index correlations by up to 58% indicating that bulk density from a near proximity is a poor representation of specific localised density. Substituting the 3D micro CT indices with 2D histomorphometric data decreased correlations by at least 33% indicating that structural identification on a plane is not representative of the full 3D architecture necessary for a complete bone strength analysis. The presented computational framework may be used to assess the roles that bone architecture and loading modes play in bone quality, and which micro CT indices are good surrogate measures for mechanical strength. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

The impact of peripheral serotonin on leptin-brain serotonin axis, bone metabolism and strength in growing rats with experimental chronic kidney disease.

PubMed

Pawlak, Dariusz; Domaniewski, Tomasz; Znorko, Beata; Oksztulska-Kolanek, Ewa; Lipowicz, Paweł; Doroszko, Michał; Karbowska, Malgorzata; Pawlak, Krystyna

2017-12-01

Chronic kidney disease (CKD) results in decreased bone strength. Serotonin (5-HT) is one of the critical regulators of bone health, fulfilling distinct functions depending on its synthesis site: brain-derived serotonin (BDS) favors osteoblast proliferation, whereas gut-derived serotonin (GDS) inhibits it. We assessed the role of BDS and peripheral leptin in the regulation of bone metabolism and strength in young rats with 5/6 nephrectomy. BDS synthesis was accelerated during CKD progression. Decreased peripheral leptin in CKD rats was inversely related to BDS content in the hypothalamus, brainstem and frontal cortex. Serotonin in these brain regions affected bone strength and metabolism in the studied animals. The direct effect of circulating leptin on bone was not shown in uremia. At the molecular level, there was an inverse association between elevated GDS and the expression of cAMP responsive element-binding protein (Creb) gene in bone of CKD animals. In contrast, increased expression of activating transcription factor 4 (Atf4) was shown, which was associated with GDS-dependent transcription factor 1 (Foxo1), clock gene - Cry-1, cell cycle genes: c-Myc, cyclins, and osteoblast differentiation genes. These results identified a previously unknown molecular pathway, by which elevated GDS can shift in Foxo1 target genes from Creb to Atf4-dependent response, disrupting the leptin-BDS - dependent gene pathway in the bone of uremic rats. Thus, in the condition of CKD the effect of BDS and GDS on bone metabolism and strength can't be distinguished. Copyright © 2017 Elsevier Inc. All rights reserved.

Bisphosphonates Improve Trabecular Bone Mass and Normalize Cortical Thickness in Ovariectomized, Osteoblast Connexin43 Deficient Mice

PubMed Central

Watkins, Marcus P.; Norris, Jin Yi; Grimston, Susan K.; Zhang, Xiaowen; Phipps, Roger J.; Ebetino, Frank H.; Civitelli, Roberto

2012-01-01

The gap junction protein, connexin43 (Cx43) controls both bone formation and osteoclastogenesis via osteoblasts and/or osteocytes. Cx43 has also been proposed to mediate an anti-apoptotic effect of bisphosphonates, potent inhibitors of bone resorption. We studied whether bisphosphonates are effective in protecting mice with a conditional Cx43 gene deletion in osteoblasts and osteocytes (cKO) from the consequences of ovariectomy on bone mass and strength. Ovariectomy resulted in rapid loss of trabecular bone followed by a slight recovery in wild type (WT) mice, and a similar degree of trabecular bone loss, albeit slightly delayed, occurred in cKO mice. Treatment with either risedronate (20µg/kg) or alendronate (40µg/kg) prevented ovariectomy-induced bone loss in both genotypes. In basal conditions, bones of cKO mice have larger marrow area, higher endocortical osteoclast number, and lower cortical thickness and strength relative to WT. Ovariectomy increased endocortical osteoclast number in WT but not in cKO mice. Both bisphosphonates prevented these increases in WT mice, and normalized endocortical osteoclast number, cortical thickness and bone strength in cKO mice. Thus, lack of osteoblast/osteocyte Cx43 does not alter bisphosphonate action on bone mass and strength in estrogen deficiency. These results support the notion that one of the main functions of Cx43 in cortical bone is to restrain osteoblast and/or osteocytes from inducing osteoclastogenesis at the endocortical surface. PMID:22750450

The BPAQ: a bone-specific physical activity assessment instrument.

PubMed

Weeks, B K; Beck, B R

2008-11-01

A newly developed bone-specific physical activity questionnaire (BPAQ) was compared with other common measures of physical activity for its ability to predict parameters of bone strength in healthy, young adults. The BPAQ predicted indices of bone strength at clinically relevant sites in both men and women, while other measures did not. Only certain types of physical activity (PA) are notably osteogenic. Most methods to quantify levels of PA fail to account for bone relevant loading. Our aim was to examine the ability of several methods of PA assessment and a new bone-specific measure to predict parameters of bone strength in healthy adults. We recruited 40 men and women (mean age 24.5). Subjects completed the modifiable activity questionnaire, Bouchard 3-day activity record, a recently published bone loading history questionnaire (BLHQ), and wore a pedometer for 14 days. We also administered our bone-specific physical activity questionnaire (BPAQ). Calcaneal broadband ultrasound attenuation (BUA) (QUS-2, Quidel) and densitometric measures (XR-36, Norland) were examined. Multiple regression and correlation analyses were performed on the data. The current activity component of BPAQ was a significant predictor of variance in femoral neck bone mineral density (BMD), lumbar spine BMD, and whole body BMD (R(2) = 0.36-0.68, p < 0.01) for men, while the past activity component of BPAQ predicted calcaneal BUA (R(2) = 0.48, p = 0.001) for women. The BPAQ predicted indices of bone strength at skeletal sites at risk of osteoporotic fracture while other PA measurement tools did not.

Fat Mass Is Positively Associated with Estimated Hip Bone Strength among Chinese Men Aged 50 Years and above with Low Levels of Lean Mass.

PubMed

Han, Guiyuan; Chen, Yu-Ming; Huang, Hua; Chen, Zhanyong; Jing, Lipeng; Xiao, Su-Mei

2017-04-24

This study investigated the relationships of fat mass (FM) and lean mass (LM) with estimated hip bone strength in Chinese men aged 50-80 years (median value: 62.0 years). A cross-sectional study including 889 men was conducted in Guangzhou, China. Body composition and hip bone parameters were generated by dual-energy X-ray absorptiometry (DXA). The relationships of the LM index (LMI) and the FM index (FMI) with bone phenotypes were detected by generalised additive models and multiple linear regression. The associations between the FMI and the bone variables in LMI tertiles were further analysed. The FMI possessed a linear relationship with greater estimated hip bone strength after adjustment for the potential confounders ( p < 0.05). Linear relationships were also observed for the LMI with most bone phenotypes, except for the cross-sectional area ( p < 0.05). The contribution of the LMI (4.0%-12.8%) was greater than that of the FMI (2.0%-5.7%). The associations between the FMI and bone phenotypes became weaker after controlling for LMI. Further analyses showed that estimated bone strength ascended with FMI in the lowest LMI tertile ( p < 0.05), but not in the subgroups with a higher LMI. This study suggested that LM played a critical role in bone health in middle-aged and elderly Chinese men, and that the maintenance of adequate FM could help to promote bone acquisition in relatively thin men.

Macroscopic anisotropic bone material properties in children with severe osteogenesis imperfecta.

PubMed

Albert, Carolyne; Jameson, John; Tarima, Sergey; Smith, Peter; Harris, Gerald

2017-11-07

Children with severe osteogenesis imperfecta (OI) typically experience numerous fractures and progressive skeletal deformities over their lifetime. Recent studies proposed finite element models to assess fracture risk and guide clinicians in determining appropriate intervention in children with OI, but lack of appropriate material property inputs remains a challenge. This study aimed to characterize macroscopic anisotropic cortical bone material properties and investigate relationships with bone density measures in children with severe OI. Specimens were obtained from tibial or femoral shafts of nine children with severe OI and five controls. The specimens were cut into beams, characterized in bending, and imaged by synchrotron radiation X-ray micro-computed tomography. Longitudinal modulus of elasticity, yield strength, and bending strength were 32-65% lower in the OI group (p<0.001). Yield strain did not differ between groups (p≥0.197). In both groups, modulus and strength were lower in the transverse direction (p≤0.009), but anisotropy was less pronounced in the OI group. Intracortical vascular porosity was almost six times higher in the OI group (p<0.001), but no differences were observed in osteocyte lacunar porosity between the groups (p=0.086). Volumetric bone mineral density was lower in the OI group (p<0.001), but volumetric tissue mineral density was not (p=0.770). Longitudinal OI bone modulus and strength were correlated with volumetric bone mineral density (p≤0.024) but not volumetric tissue mineral density (p≥0.099). Results indicate that cortical bone in children with severe OI yields at the same strain as normal bone, and that their decreased bone material strength is associated with reduced volumetric bone mineral density. These results will enable the advancement of fracture risk assessment capability in children with severe OI. Copyright © 2017 Elsevier Ltd. All rights reserved.

Extended fatigue life of a catalyst-free self-healing acrylic bone cement using microencapsulated 2-octyl cyanoacrylate

PubMed Central

Brochu, Alice B.W.; Matthys, Oriane B.; Craig, Stephen L.; Reichert, William M.

2014-01-01

The tissue adhesive 2-octyl cyanoacrylate (OCA) was encapsulated in polyurethane microshells and incorporated into bone cement to form a catalyst free, self-healing bone cement comprised of all clinically approved components. The bending strength, modulus, and fatigue lifetime were investigated in accordance with ASTM and ISO standards for the testing of PMMA bone cement. The bending strength of bone cement specimens decreased with increasing wt% capsules content for capsules without or with OCA, with specimens of < 5 wt% capsule content showing minimal effect. In contrast, bone cement bending modulus was insensitive to capsule content. Load controlled fatigue testing was performed in air at room temperature on capsule free bone cement (0 wt%), bone cement with 5 wt% OCA-free capsules (5 wt% No OCA), and 5 wt% OCA-containing capsules (5 wt% OCA). Specimens were tested at a frequency of 5 Hz at maximum stresses of 90%, 80%, 70% and 50% of each specimen's bending strength until failure. The 5 wt% OCA exhibited significant self-healing at 70% and 50% of its reference strength (p < 0.05). Fatigue testing of all three specimen types in air at 22 MPa (50% of reference strength of the 5 wt% OCA specimens) showed that the cycles to failure of OCA-containing specimens was increased by two-fold compared to the OCA-free and capsule-free specimens. This study represents the first demonstration of dynamic, catalyst-free self-healing in a biomaterial formulation. PMID:24825796

Effect of once-yearly zoledronic acid on the spine and hip as measured by quantitative computed tomography: results of the HORIZON Pivotal Fracture Trial

PubMed Central

Lang, T.; Boonen, S.; Cummings, S.; Delmas, P. D.; Cauley, J. A.; Horowitz, Z.; Kerzberg, E.; Bianchi, G.; Kendler, D.; Leung, P.; Man, Z.; Mesenbrink, P.; Eriksen, E. F.; Black, D. M.

2016-01-01

Summary Changes in bone mineral density and bone strength following treatment with zoledronic acid (ZOL) were measured by quantitative computed analysis (QCT) or dual-energy X-ray absorptiometry (DXA). ZOL treatment increased spine and hip BMD vs placebo, assessed by QCT and DXA. Changes in trabecular bone resulted in increased bone strength. Introduction To investigate bone mineral density (BMD) changes in trabecular and cortical bone, estimated by quantitative computed analysis (QCT) or dual-energy X-ray absorptiometry (DXA), and whether zoledronic acid 5 mg (ZOL) affects bone strength. Methods In 233 women from a randomized, controlled trial of once-yearly ZOL, lumbar spine, total hip, femoral neck, and trochanter were assessed by DXA and QCT (baseline, Month 36). Mean percentage changes from baseline and between-treatment differences (ZOL vs placebo, t-test) were evaluated. Results Mean between-treatment differences for lumbar spine BMD were significant by DXA (7.0%, p<0.01) and QCT (5.7%, p<0.0001). Between-treatment differences were significant for trabecular spine (p=0.0017) [non-parametric test], trabecular trochanter (10.7%, p<0.0001), total hip (10.8%, p<0.0001), and compressive strength indices at femoral neck (8.6%, p=0.0001), and trochanter (14.1%, p<0.0001). Conclusions Once-yearly ZOL increased hip and spine BMD vs placebo, assessed by QCT vs DXA. Changes in trabecular bone resulted in increased indices of compressive strength. PMID:19802508

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shrivastava, Pragya; Dalai, Sridhar; Vijayalakshmi, S.

With an increasing demand of biocompatible bone substitutes for the treatment of bone diseases and bone tissue regeneration, bioactive glass composites are being tested to improvise the osteoconductive as well as osteoinductive properties. Nanobioactive glass (nBG) composites, having composition of SiO{sub 2} 70 mol%, CaO 26 mol % and P{sub 2}O{sub 5} 4 mol% were prepared by Freeze drying method using PEG-PPG-PEG co-polymer. Polymer addition improves the mechanical strength and porosity of the scaffold of nBG. Nano Bioactive glass composites upon implantation undergo specific reactions leading to the formation of crystalline hydroxyapatite (HA). This is tested in vitro using Simulatedmore » Body Fluid (SBF). This high strength hydroxyapatite (HA) layer acts as osteoconductive in cellular environment, by acting as mineral base of bones, onto which new bone cells proliferate leading to new bone formation. Strength of the nBG composites as well as HA is in the range of cortical and cancellous bone, thus proving significant for bone tissue regeneration substitutes.« less

Associations of physical activity duration, frequency, and load with volumetric BMD, geometry, and bone strength in young girls

PubMed Central

Farr, Joshua N.; Blew, Robert M.; Lee, Vinson R.; Lohman, Timothy G.; Going, Scott B.

2011-01-01

Purpose This study evaluated the associations of physical activity (PA) duration, frequency, load, and their interaction (total PA score = duration × frequency × load) with volumetric bone mineral density, geometry, and indices of bone strength in young girls. Methods 465 girls (aged 8–13 years) completed a past year physical activity questionnaire (PYPAQ) which inquires about the frequency (days/week) and duration (average minutes/session) of leisure-time PA and sports. Load (peak strain score) values were assigned to each activity based on ground reaction forces. Peripheral quantitative computed tomography was used to assess bone parameters at metaphyseal and diaphyseal sites of the femur and tibia of the non-dominant leg. Results Correlations across all skeletal sites between PA duration, frequency, load and periosteal circumference (PC), bone strength index (BSI), and strength-strain index (SSI) were significant (p ≤ 0.05), although low (0.10–0.17). A 2.7–3.7% greater PC across all skeletal sites was associated with a high compared to a low PYPAQ score. Also, a high PYPAQ score was associated with greater BSI (6.5–8.7%) at metaphyseal sites and SSI (7.5–8.1%) at diaphyseal sites of the femur and tibia. The effect of a low PYPAQ score on bone geometric parameters and strength was greater than a high PYPAQ score. Conclusions PA duration, frequency, and load were all associated with bone geometry and strength, although their independent influences were modest and site specific. Low levels of PA may compromise bone development whereas high levels have only a small benefit over more average levels. PMID:20694457

Biaxial Normal Strength Behavior in the Axial-Transverse Plane for Human Trabecular Bone—Effects of Bone Volume Fraction, Microarchitecture, and Anisotropy

PubMed Central

Sanyal, Arnav; Keaveny, Tony M.

2013-01-01

The biaxial failure behavior of the human trabecular bone, which has potential relevance both for fall and gait loading conditions, is not well understood, particularly for low-density bone, which can display considerable mechanical anisotropy. Addressing this issue, we investigated the biaxial normal strength behavior and the underlying failure mechanisms for human trabecular bone displaying a wide range of bone volume fraction (0.06–0.34) and elastic anisotropy. Micro-computer tomography (CT)-based nonlinear finite element analysis was used to simulate biaxial failure in 15 specimens (5 mm cubes), spanning the complete biaxial normal stress failure space in the axial-transverse plane. The specimens, treated as approximately transversely isotropic, were loaded in the principal material orientation. We found that the biaxial stress yield surface was well characterized by the superposition of two ellipses—one each for yield failure in the longitudinal and transverse loading directions—and the size, shape, and orientation of which depended on bone volume fraction and elastic anisotropy. However, when normalized by the uniaxial tensile and compressive strengths in the longitudinal and transverse directions, all of which depended on bone volume fraction, microarchitecture, and mechanical anisotropy, the resulting normalized biaxial strength behavior was well described by a single pair of (longitudinal and transverse) ellipses, with little interspecimen variation. Taken together, these results indicate that the role of bone volume fraction, microarchitecture, and mechanical anisotropy is mostly accounted for in determining the uniaxial strength behavior and the effect of these parameters on the axial-transverse biaxial normal strength behavior per se is minor. PMID:24121715

Gravity, Calcium, and Bone: Update, 1989

NASA Technical Reports Server (NTRS)

Arnaud, Sara B.; Morey-Holton, Emily

1991-01-01

Some of the results of recent short-term flights and ground-based experiments that have contributed new insights into skeletal adaptation, calcium metabolism, and growth processes in 0 g, are highlighted. After 6 months in space, bone demineralization, invariably involving the os calcis, was found not to extend to the lumbar spine in 4 exercising cosmonauts. A flight experiment in the Space Shuttle crew has documented the early events in the calcium endocrine system during spaceflight. On the ground, brief and long-term bed rest studies of healthy volunteers in the head-down tile (HDT) model of weightlessness were completed. The skeleton of the adult male responds more rapidly to unloading than previously recognized. Regional changes in bone density can be quantified in only 30 days, are highly individual, and follow the direction of gravitational forces in the HDT model during inactivity. Bone biopsy results in healthy volunteers after bed rest differ from results in paraplegics from the same sampling site. Flight experiments in growing rats reveal changes in the composition of bone mineral and matrix in the femur postflight that were found to be highly regional and suggestive of an effect of gravity on mineral distribution. These observations may be relevant to the results from an earlier Cosmos flight where artificial gravity in space was found to maintain bone strength, but not to correct the radial growth deficit.

Effect of thumb joint mobilization on pressure pain threshold in elderly patients with thumb carpometacarpal osteoarthritis.

PubMed

Villafañe, Jorge H; Silva, Guillermo B; Fernandez-Carnero, Josue

2012-02-01

This study evaluated the effects of Maitland's passive accessory mobilization on local hypoalgesia and strength in thumb carpometacarpal osteoarthritis (TCOA). Twenty-eight patients between 70 and 90 years old with secondary TCOA were randomized into glide mobilization and sham groups. This study was designed as a double-blind, randomized controlled trial. Therapy consisted of Maitland's passive accessory mobilization of the dominant hand during 4 sessions over 2 weeks. We measured pressure pain threshold (PPT) at the trapeziometacarpal joint (TMJ), the tubercle of the scaphoid bone, and the unciform apophysis of the hamate bone by algometry. The tip and tripod pinch strength was also measured. Grip strength was measured by a grip dynamometer. Measurements were taken before treatment and after 1 week (first follow-up [FU]) and 2 weeks (second FU). All values in sham group remained unchanged along the treatment period. In the treated group, the PPT in the TMJ was 3.85 ± 0.35 kg/cm(2), which increased after treatment to 3.99 ± 0.37 and was maintained at the same level during the first FU 3.94 ± 0.39 and second FU 4.74 ± 0.40. In contrast, we found no differences in PPT in the other studied structures after treatment. Similarly, tip, tripod pinch, and grip strength remained without change after treatment. Passive accessory mobilization increased PPT in the TMJ; however, it did not increase motor function in patients with TCOA. Copyright © 2012 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

High-strength, surface-porous polyether-ether-ketone for load-bearing orthopedic implants.

PubMed

Evans, Nathan T; Torstrick, F Brennan; Lee, Christopher S D; Dupont, Kenneth M; Safranski, David L; Chang, W Allen; Macedo, Annie E; Lin, Angela S P; Boothby, Jennifer M; Whittingslow, Daniel C; Carson, Robert A; Guldberg, Robert E; Gall, Ken

2015-02-01

Despite its widespread clinical use in load-bearing orthopedic implants, polyether-ether-ketone (PEEK) is often associated with poor osseointegration. In this study, a surface-porous PEEK material (PEEK-SP) was created using a melt extrusion technique. The porous layer was 399.6±63.3 μm thick and possessed a mean pore size of 279.9±31.6 μm, strut spacing of 186.8±55.5 μm, porosity of 67.3±3.1% and interconnectivity of 99.9±0.1%. Monotonic tensile tests showed that PEEK-SP preserved 73.9% of the strength (71.06±2.17 MPa) and 73.4% of the elastic modulus (2.45±0.31 GPa) of as-received, injection-molded PEEK. PEEK-SP further demonstrated a fatigue strength of 60.0 MPa at one million cycles, preserving 73.4% of the fatigue resistance of injection-molded PEEK. Interfacial shear testing showed the pore layer shear strength to be 23.96±2.26 MPa. An osseointegration model in the rat revealed substantial bone formation within the pore layer at 6 and 12 weeks via microcomputed tomography and histological evaluation. Ingrown bone was more closely apposed to the pore wall and fibrous tissue growth was reduced in PEEK-SP when compared to non-porous PEEK controls. These results indicate that PEEK-SP could provide improved osseointegration while maintaining the structural integrity necessary for load-bearing orthopedic applications. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Prevention of Bone Loss after Acute SCI by Zoledronic Acid: Durability, Effect on Bone Strength, and Use of Biomarkers to Guide Therapy

DTIC Science & Technology

2016-10-01

6 and 12 months during the first year; participants are re-randomized after 12 months with subsequent data collection at 18 and 24 months. Currently...bone mass, bone strength, osteoporosis, zoledronic acid 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18 . NUMBER OF PAGES 19a. NAME...and bone markers will be obtained at baseline, 3 months, 6 months, 12 months, 18 months and 24 months. KEYWORDS: spinal cord

Calcium requirements of growing rats based on bone mass, structure, or biomechanical strength are similar.

PubMed

Hunt, Janet R; Hunt, Curtiss D; Zito, Carol Ann; Idso, Joseph P; Johnson, LuAnn K

2008-08-01

Although calcium (Ca) supplementation increases bone density, the increase is small and the effect on bone strength and fracture risk is uncertain. To investigate if bone mass, morphology, and biomechanical properties are affected by deficient to copious dietary Ca concentrations, the long bones (tibia and femur) of growing female Sprague-Dawley rats (8/group) were assessed after 13 wk of consuming 1, 2, 3, 4, 5, 6, or 7 g Ca/kg of a modified AIN-93G diet. Dietary phosphorous (P) and vitamin D remained constant at recommended concentrations. The assessment included mineralization, density, biomechanical properties of breaking by a 3-point flexure test, and morphological properties by microcomputed topography scanning of trabecular bone of the proximal tibia metaphysis. Dietary treatment did not affect food intake, weight gain, renal and muscle Ca concentrations, and bone hydroxyproline. All bone parameters measured were significantly impaired by Ca deficiency in rats fed the diet containing 1 g Ca/kg. Modest impairments occurred with some parameters (bone density, biomechanical bending moment, modulus of elasticity, and stress) in rats fed 2 g Ca/kg, but all parameters stabilized between 2 and 3 g/kg diet, with no differences between 3 and 7 g/kg. The results suggest that a threshold response in bone Ca retention or bone mass at approximately 2.5 g Ca/kg diet is associated with similar threshold responses in bone breaking strength and related biomechanics as well as trabecular structural properties. There was no evidence of a relative P deficiency or of improved or impaired bone strength and structure as Ca intakes increased beyond those needed to maximize bone density.

Sex differences in parameters of bone strength in new recruits: beyond bone density.

PubMed

Evans, Rachel K; Negus, Charles; Antczak, Amanda J; Yanovich, Ran; Israeli, Eran; Moran, Daniel S

2008-11-01

Stress fracture (SF) injuries in new recruits have long been attributed to low bone mineral density (BMD). Low areal BMD assessed using two-dimensional dual-energy x-ray absorptiometry imaging, however, reflects structural density and is affected by smaller measures of bone geometry. Recent studies support a relationship between bone size and SF and indicate that slender bones are more susceptible to damage under identical loading conditions. Peripheral quantitative computed tomography (pQCT) is a three-dimensional imaging tool that provides measures of tissue density and geometry parameters of the tibia, a common site of SF. To evaluate sex differences in parameters of volumetric BMD (vBMD), geometry, and strength of the tibia in new recruits using a novel pQCT image analysis procedure. pQCT images were obtained from 128 healthy men and women (20 male, 108 female, aged 18-21 yr) entering a 4-month gender-integrated combat training program in the Israeli Defense Forces. Tibial scans taken at sites 4% (trabecular bone), 38%, and 66% (cortical bone) from the distal end plate were analyzed using MATLAB to assess whole-bone and regional parameters. Measures included vBMD, geometry (diameter, area, cortical thickness, and canal radius), and strength (moments of inertia and bone strength and slenderness indices). With the exception of normalized canal radius, which did not differ between sexes, all measures of bone geometry (P < 0.0001) and strength (P < 0.0001 to P = 0.07) were greater in men. Women exhibited 2.7% to 3.0% greater cortical vBMD than men, whereas trabecular vBMD was 8.4% lower in women (P < 0.001). These differences remained significant after adjusting for body size. Sex differences in bone geometry and mineralization of the tibia may contribute to a decreased ability to withstand the demands imposed by novel, repetitive exercise in untrained individuals entering recruit training.

Bone microstructure in men assessed by HR-pQCT: Associations with risk factors and differences between men with normal, low, and osteoporosis-range areal BMD.

PubMed

Okazaki, Narihiro; Burghardt, Andrew J; Chiba, Ko; Schafer, Anne L; Majumdar, Sharmila

2016-12-01

The primary objective of this study was to analyze the relationships between bone microstructure and strength, and male osteoporosis risk factors including age, body mass index, serum 25-hydroxyvitamin D level, and testosterone level. A secondary objective was to compare microstructural and strength parameters between men with normal, low, and osteoporosis-range areal bone mineral density (aBMD). Seventy-eight healthy male volunteers (mean age 62.4 ± 7.8 years, range 50-84 years) were recruited. The participants underwent dual-energy X-ray absorptiometry (DXA) and high-resolution peripheral quantitative computed tomography (HR-pQCT) of the ultra-distal radius and tibia. From the HR-pQCT images, volumetric bone mineral density (BMD) and cortical and trabecular bone microstructure were evaluated, and bone strength and cortical load fraction (Ct.LF) were estimated using micro-finite element analysis (μFEA). Age was more strongly correlated with bone microstructure than other risk factors. Age had significant positive correlations with cortical porosity at both ultra-distal radius and tibia ( r  = 0.36, p  = 0.001, and r  = 0.47, p  < 0.001, respectively). At the tibia, age was negatively correlated with cortical BMD, whereas it was positively correlated with trabecular BMD. In μFEA, age was negatively correlated with Ct.LF, although not with bone strength. Compared with men with normal aBMD, men with low or osteoporosis-range aBMD had significantly poor trabecular bone microstructure and lower bone strength at the both sites, while there was no significant difference in cortical bone. Cortical bone microstructure was negatively affected by aging, and there was a suggestion that the influence of aging may be particularly important at the weight-bearing sites.

A Flexible Method for Producing F.E.M. Analysis of Bone Using Open-Source Software

NASA Technical Reports Server (NTRS)

Boppana, Abhishektha; Sefcik, Ryan; Myers, Jerry G.; Lewandowski, Beth

2016-01-01

Individuals who experience decreases in load-bearing bone densities can be subject to a higher risk of bone fracture during daily activity. Astronauts may lose up to nine percent of their load-bearing bone density for every month they spend in space [1]. Because of this, specialized countermeasures reduce percent loss in bone density and reduce fracture risk upon returning to Earth. Astronauts will typically not be at risk for fracture during spaceflight, because of the lesser loads experienced in microgravity conditions. However, once back on Earth, astronauts have an increased risk for bone fracture as a result of weakened bone and return to 1G conditions [2]. It is therefore important to understand the significance of any bone density loss in addition to developing exercises in an attempt to limit losses in bone strength. NASA seeks to develop a deeper understanding of fracture risk through the development of a computational bone strength model to assess the bone fracture risk of astronauts pre-flight and post-flight. This study addresses the several key processes needed to develop such strength analyses using medical image processing and finite element modeling.

Effect of surface roughness of hydroxyapatite-coated titanium on the bone-implant interface shear strength.

PubMed

Hayashi, K; Inadome, T; Tsumura, H; Nakashima, Y; Sugioka, Y

1994-11-01

We have investigated the bone-implant interface shear strength of hydroxyapatite (HA)-coated Ti-6Al-4V (HA-coating A) (roughness average, Ra = 3.4 +/- 0.5 microns) and HA-coated Ti-6Al-4V with a rougher surface (HA-coating B) (Ra = 8.4 +/- 1.8 microns). There was no significant difference between HA-coating A and HA-coating B implants with respect to the bone-implant interface shear strength as determined in push-out tests using the transcortical model in adult dogs. The bone-implant interface shear strength of bead-coated porous Ti-6Al-4V was significantly greater than that of both HA-coating A and HA-coating B implants. The failure site, as determined by scanning electron microscopy, was the coating-substrate interface, not the coating-bone interface. This indicates a need to protect the HA coating from the direct shear forces. HA coating enhances early bone growth into the porous surface of the implant. Long-term fixation should depend on bone anchoring to this porous surface. Hydroxyapatite coatings must be developed which do not obstruct the pores of the surface of the implant.

Fat, Sugar, and Bone Health: A Complex Relationship

PubMed Central

Tian, Li; Yu, Xijie

2017-01-01

With people aging, osteoporosis is expected to increase notably. Nutritional status is a relatively easily-modified risk factor, associated with many chronic diseases, and is involved in obesity, diabetes, and coronary heart disease (CHD), along with osteoporosis. Nutrients, such as fats, sugars, and proteins, play a primary function in bone metabolism and maintaining bone health. In Western nations, diets are generally high in saturated fats, however, currently, the nutritional patterns dominating in China continue to be high in carbohydrates from starch, cereals, and sugars. Moreover, high fat or high sugar (fructose, glucose, or sucrose) impart a significant impact on bone structural integrity. Due to diet being modifiable, demonstrating the effects of nutrition on bone health can provide an approach for osteoporosis prevention. Most researchers have reported that a high-fat diet consumption is associated with bone mineral density (BMD) and, as bone strength diminishes, adverse microstructure changes occur in the cancellous bone compartment, which is involved with lipid metabolism modulation disorder and the alteration of the bone marrow environment, along with an increased inflammatory environment. Some studies, however, demonstrated that a high-fat diet contributes to achieving peak bone mass, along with microstructure, at a younger age. Contrary to these results, others have shown that a high-fructose diet consumption leads to stronger bones with a superior microarchitecture than those with the intake of a high-glucose diet and, at the same time, research indicated that a high-fat diet usually deteriorates cancellous bone parameters, and that the incorporation of fructose into a high-fat diet did not aggravate bone mass loss. High-fat/high-sucrose diets have shown both beneficial and detrimental influences on bone metabolism. Combined, these studies showed that nutrition exerts different effects on bone health. Thus, a better understanding of the regulation between dietary nutrition and bone health might provide a basis for the development of strategies to improve bone health by modifying nutritional components. PMID:28513571

Fat, Sugar, and Bone Health: A Complex Relationship.

PubMed

Tian, Li; Yu, Xijie

2017-05-17

With people aging, osteoporosis is expected to increase notably. Nutritional status is a relatively easily-modified risk factor, associated with many chronic diseases, and is involved in obesity, diabetes, and coronary heart disease (CHD), along with osteoporosis. Nutrients, such as fats, sugars, and proteins, play a primary function in bone metabolism and maintaining bone health. In Western nations, diets are generally high in saturated fats, however, currently, the nutritional patterns dominating in China continue to be high in carbohydrates from starch, cereals, and sugars. Moreover, high fat or high sugar (fructose, glucose, or sucrose) impart a significant impact on bone structural integrity. Due to diet being modifiable, demonstrating the effects of nutrition on bone health can provide an approach for osteoporosis prevention. Most researchers have reported that a high-fat diet consumption is associated with bone mineral density (BMD) and, as bone strength diminishes, adverse microstructure changes occur in the cancellous bone compartment, which is involved with lipid metabolism modulation disorder and the alteration of the bone marrow environment, along with an increased inflammatory environment. Some studies, however, demonstrated that a high-fat diet contributes to achieving peak bone mass, along with microstructure, at a younger age. Contrary to these results, others have shown that a high-fructose diet consumption leads to stronger bones with a superior microarchitecture than those with the intake of a high-glucose diet and, at the same time, research indicated that a high-fat diet usually deteriorates cancellous bone parameters, and that the incorporation of fructose into a high-fat diet did not aggravate bone mass loss. High-fat/high-sucrose diets have shown both beneficial and detrimental influences on bone metabolism. Combined, these studies showed that nutrition exerts different effects on bone health. Thus, a better understanding of the regulation between dietary nutrition and bone health might provide a basis for the development of strategies to improve bone health by modifying nutritional components.

Mineralisation and mechanical strength of the glenoid cavity subchondral bone plate.

PubMed

Kraljević, Marko; Zumstein, Valentin; Wirz, Dieter; Hügli, Rolf; Müller-Gerbl, Magdalena

2011-12-01

Failures in total shoulder replacements are often due to aseptic loosening of the glenoid component; the subchondral bone plate is an important factor governing primary fixation of implant materials. Therefore, we investigated characteristic mineralisation patterns of the subchondral bone plate, which demonstrate long-term stress on articular surfaces, age-related changes, postsurgical biomechanical situations and regions of fixation. Using computed tomography osteo-absorptiometry (CT-OAM), these distribution patterns can be demonstrated in vivo. The aim of this study was to investigate the relationship between subchondral bone-plate mineralisation measured with CT-OAM and the mechanical strength measured by indentation. A total of 32 cadaverous glenoid cavities were evaluated by CT-OAM and indentation testing. Linear regression was used to compare mineralisation and strength of the subchondral bone plate. Results showed two patterns of mineralisation distribution. Twenty-eight cavities were related to bicentric distribution pattern and four showed a single maximum. The correlation coefficient between CT-OAM density and subchondral bone-plate strength was determined to be between 0.62 and 0.96 (P < 0.02). Long-term stress affects not only the subchondral but also the underlying cancellous bone. It therefore can be assumed that mineralisation patterns of the subchondral bone plate continue in cancellous bone. Areas of high density could serve as anchoring locations for orthopaedic implants in resurfacing the glenoid cavity.

Differential osteogenic activity of osteoprogenitor cells on HA and TCP/HA scaffold of tissue engineered bone.

PubMed

Ng, Angela M H; Tan, K K; Phang, M Y; Aziyati, O; Tan, G H; Isa, M R; Aminuddin, B S; Naseem, M; Fauziah, O; Ruszymah, B H I

2008-05-01

Biomaterial, an essential component of tissue engineering, serves as a scaffold for cell attachment, proliferation, and differentiation; provides the three dimensional (3D) structure and, in some applications, the mechanical strength required for the engineered tissue. Both synthetic and naturally occurring calcium phosphate based biomaterial have been used as bone fillers or bone extenders in orthopedic and reconstructive surgeries. This study aims to evaluate two popular calcium phosphate based biomaterial i.e., hydroxyapatite (HA) and tricalcium phosphate/hydroxyapatite (TCP/HA) granules as scaffold materials in bone tissue engineering. In our strategy for constructing tissue engineered bone, human osteoprogenitor cells derived from periosteum were incorporated with human plasma-derived fibrin and seeded onto HA or TCP/HA forming 3D tissue constructs and further maintained in osteogenic medium for 4 weeks to induce osteogenic differentiation. Constructs were subsequently implanted intramuscularly in nude mice for 8 weeks after which mice were euthanized and constructs harvested for evaluation. The differential cell response to the biomaterial (HA or TCP/HA) adopted as scaffold was illustrated by the histology of undecalcified constructs and evaluation using SEM and TEM. Both HA and TCP/HA constructs showed evidence of cell proliferation, calcium deposition, and collagen bundle formation albeit lesser in the former. Our findings demonstrated that TCP/HA is superior between the two in early bone formation and hence is the scaffold material of choice in bone tissue engineering. Copyright 2007 Wiley Periodicals, Inc.

Terrestrial applications of bone and muscle research in microgravity

NASA Astrophysics Data System (ADS)

Booth, F. W.

1994-08-01

Major applications to people on Earth are possible from NASA-sponsored research on bone and muscle which is conducted either in microgravity or on Earth using models mimicking microgravity. In microgravity bone and muscle mass are lost. Humans experience a similar loss under certain conditions on Earth. Bone and muscle loss exist on Earth as humans age from adulthood to senescence, during limb immobilization for healing of orthopedic injuries, during wheelchair confinement because of certain diseases, and during chronic bed rest prescribed for curing of diseases. NASA-sponsored research is dedicated to learning both what cause bone and muscle loss as well as finding out how to prevent this loss. The health ramifications of these discoveries will have major impact. Objective 1.6 of Healthy People 2000, a report from the U.S. Department of Health and Human Services, states that the performance of physical activities that improve muscular strength, muscular endurance, and flexibility is particularly important to maintaining functional independence and social integration in older adults /1/. This objective further states that these types of physical activities are important because they may protect against disability, an event which costs the U.S. economy hugh sums of money. Thus NASA research related to bone and muscle loss has potential major impact on the quality of life in the U.S. Relative to its potential health benefits, NASA and Congressional support of bone and muscle research is funded is a very low level.

Terrestrial applications of bone and muscle research in microgravity.

PubMed

Booth, F W

1994-01-01

Major applications to people on Earth are possible from NASA-sponsored research on bone and muscle which is conducted either in microgravity or on Earth using models mimicking microgravity. In microgravity bone and muscle mass are lost. Humans experience a similar loss under certain conditions on Earth. Bone and muscle loss exist on Earth as humans age from adulthood to senescence, during limb immobilization for healing of orthopedic injuries, during wheelchair confinement because of certain diseases, and during chronic bed rest prescribed for curing of diseases. NASA-sponsored research is dedicated to learning both what cause bone and muscle loss as well as finding out how to prevent this loss. The health ramifications of these discoveries will have major impact. Objective 1.6 of Healthy People 2000, a report from the U.S. Department of Health and Human Services, states that the performance of physical activities that improve muscular strength, muscular endurance, and flexibility is particularly important to maintaining functional independence and social integration in older adults. This objective further states that these types of physical activities are important because they may protect against disability, an event which costs the U.S. economy huge sums of money. Thus NASA research related to bone and muscle loss has potential major impact on the quality of life in the U.S. Relative to its potential health benefits, NASA and Congressional support of bone and muscle research is funded at a very low level.

Does maximum torque mean optimal pullout strength of screws?

PubMed

Tankard, Sara E; Mears, Simon C; Marsland, Daniel; Langdale, Evan R; Belkoff, Stephen M

2013-04-01

To determine the relationship between insertion torque and pullout strength of 3.5-mm-diameter cortical screws in cadaveric humeri with different bone mineral densities (BMDs). Five pairs of human humeri from each of 3 BMD groups (normal, osteopenic, and osteoporotic) were used. Holes were drilled in each humerus, and maximum insertion torque (T(max)) was measured by tightening a screw until stripping occurred. In the remaining holes, screws were tightened to 50%, 70%, or 90% of the T(max). A servohydraulic testing machine pulled each screw out at 1 mm/s while resulting force and axial displacement were recorded at 10 Hz. The authors checked for an effect of insertion torque (percent T(max)) on pullout strength using a general linearized and latent mixed model (Stata10), controlling for cortical thickness and BMD (T-score). Pullout strength for normal and osteoporotic bone was greatest for screws inserted to 50% T(max) and was significantly greater than that at T(max) but not significantly different from that at 70% or 90% T(max). For osteopenic bone, pullout strength was greatest at 70% peak torque, but it was not significantly different from the pullout strength at the 50% or 90% T(max) levels. Tightening screws beyond 50% T(max) does not increase pullout strength of the screw and may place bone at risk for damage that might result in loss of fixation. Even after adjusting for bone thickness and density, there is no clear relationship between pullout strength and screw torque.

Discordance between Prevalent Vertebral Fracture and Vertebral Strength Estimated by the Finite Element Method Based on Quantitative Computed Tomography in Patients with Type 2 Diabetes Mellitus

PubMed Central

2015-01-01

Background Bone fragility is increased in patients with type 2 diabetes mellitus (T2DM), but a useful method to estimate bone fragility in T2DM patients is lacking because bone mineral density alone is not sufficient to assess the risk of fracture. This study investigated the association between prevalent vertebral fractures (VFs) and the vertebral strength index estimated by the quantitative computed tomography-based nonlinear finite element method (QCT-based nonlinear FEM) using multi-detector computed tomography (MDCT) for clinical practice use. Research Design and Methods A cross-sectional observational study was conducted on 54 postmenopausal women and 92 men over 50 years of age, all of whom had T2DM. The vertebral strength index was compared in patients with and without VFs confirmed by spinal radiographs. A standard FEM procedure was performed with the application of known parameters for the bone material properties obtained from nondiabetic subjects. Results A total of 20 women (37.0%) and 39 men (42.4%) with VFs were identified. The vertebral strength index was significantly higher in the men than in the women (P<0.01). Multiple regression analysis demonstrated that the vertebral strength index was significantly and positively correlated with the spinal bone mineral density (BMD) and inversely associated with age in both genders. There were no significant differences in the parameters, including the vertebral strength index, between patients with and without VFs. Logistic regression analysis adjusted for age, spine BMD, BMI, HbA1c, and duration of T2DM did not indicate a significant relationship between the vertebral strength index and the presence of VFs. Conclusion The vertebral strength index calculated by QCT-based nonlinear FEM using material property parameters obtained from nondiabetic subjects, whose risk of fracture is lower than that of T2DM patients, was not significantly associated with bone fragility in patients with T2DM. This discordance may indirectly suggest that patients with T2DM have deteriorated bone material compared with nondiabetic subjects, a potential cause of bone fragility in T2DM patients. PMID:26642210

Time course of disassociation of bone formation signals with bone mass and bone strength in sclerostin antibody treated ovariectomized rats.

PubMed

Ma, Yanfei L; Hamang, Matthew; Lucchesi, Jonathan; Bivi, Nicoletta; Zeng, Qianqiang; Adrian, Mary D; Raines, Sarah E; Li, Jiliang; Kuhstoss, Stuart A; Obungu, Victor; Bryant, Henry U; Krishnan, Venkatesh

2017-04-01

Sclerostin antibodies increase bone mass by stimulating bone formation. However, human and animal studies show that bone formation increases transiently and returns to pre-treatment level despite ongoing antibody treatment. To understand its mechanism of action, we studied the time course of bone formation, correlating the rate and extent of accrual of bone mass and strength after sclerostin antibody treatment. Ovariectomized (OVX) rats were treated with a sclerostin-antibody (Scle-ab) at 20mg/kg sc once weekly and sacrificed at baseline and 2, 3, 4, 6, and 8weeks post-treatment. In Scle-ab treated rats, serum PINP and OCN rapidly increased at week 1, peaked around week 3, and returned to OVX control levels by week 6. Transcript analyses from the distal femur revealed an early increase in bone formation followed by a sustained decrease in bone resorption genes. Lumbar vertebral (LV) osteoblast surface increased 88% by week 2, and bone formation rate (BFR/BS) increased 138% by week 4. Both parameters were below OVX control by week 8. Bone formation was primarily a result of modeling based formation. Endocortical and periosteal BFR/BS peaked around week 4 at 313% and 585% of OVX control, respectively. BFR/BS then declined but remained higher than OVX control on both surfaces through week 8. Histomorphometric analyses showed LV-BV/TV did not further increase after week 4, while BMD continued to increase at LV, mid femur (MF), and femoral neck (FN) through week 8. Biomechanical tests showed a similar improvement in bone strength through 8weeks in MF and FN, but bone strength plateaued between weeks 6 and 8 for LV. Our data suggest that bone formation with Scle-ab treatment is rapid and modeling formation dominated in OVX rats. Although transient, the bone formation response persists longer in cortical than trabecular bone. Copyright © 2016 Elsevier Inc. All rights reserved.

Drinking water fluoridation and bone.

PubMed

Allolio, B; Lehmann, R

1999-01-01

Drinking water fluoridation has an established role in the prevention of dental caries, but may also positively or negatively affect bone. In bone fluoride is incorporated into hydroxylapatite to form the less soluble fluoroapatite. In higher concentrations fluoride stimulates osteoblast activity leading to an increase in cancellous bone mass. As optimal drinking water fluoridation (1 mg/l) is widely used, it is of great interest, whether long-term exposition to artificial water fluoridation has any impact on bone strength, bone mass, and -- most importantly -- fracture rate. Animal studies suggest a biphasic pattern of the effect of drinking water fluoridation on bone strength with a peak strength at a bone fluoride content of 1200 ppm followed by a decline at higher concentrations eventually leading to impaired bone quality. These changes are not paralleled by changes in bone mass suggesting that fluoride concentrations remain below the threshold level required for activation of osteoblast activity. Accordingly, in most epidemiological studies in humans bone mass was not altered by optimal drinking water fluoridation. In contrast, studies on the effect on hip fracture rate gave conflicting results ranging from an increased fracture incidence to no effect, and to a decreased fracture rate. As only ecological studies have been performed, they may be biased by unknown confounding factors -- the so-called ecological fallacy. However, the combined results of these studies indicate that any increase or decrease in fracture rate is likely to be small. It has been calculated that appropriately designed cohort studies to solve the problem require a sample size of >400,000 subjects. Such studies will not be performed in the foreseeable future. Future investigations in humans should, therefore, concentrate on the effect of long-term drinking water fluoridation on bone fluoride content and bone strength.

Biodegradable hybrid tissue engineering scaffolds for reconstruction of large bone defects

NASA Astrophysics Data System (ADS)

Barati, Danial

Complex skeletal injuries and large bone fractures are still a significant clinical problem in US. Approximately 1.5 million Americans (veterans, their families, and civilians) every year suffer from bone loss due to traumatic skeletal injuries, infection, and resection of primary tumors that require extensive grafting to bridge the gap. The US bone graft market is over $2.2 billion a year. Due to insufficient mechanical stability, lack of vascularity, and inadequate resorption of the graft, patients with traumatic large skeletal injuries undergo multiple costly operations followed by extensive recovery steps to maintain proper bone alignment and length. Current strategies for repairing damaged or diseased bones include autologous or allograft bone transplantations. However, limited availability of autografts and risk of disease transmission associated with allografts have necessitated the search for the development of new bone graft options and strategies. The overall goal of this project is to develop a much-needed bone-mimetic engineered graft as a substitute for current strategies providing required bone grafts for reconstruction of large bone defects. This project will use the structure of natural cortical bone as a guide to produce an engineered bone graft with balanced strength, osteogenesis, vascularization, and resorption. The outcome of this project will be a biodegradable hybrid scaffold system (similar to natural cortical bone) including a mechanically strong scaffold allowing for mechanical stability of the load-bearing defect site and a soft and highly porous structure such as a hydrogel phase which will allow for efficient cell and growth factor delivery into the defect implantation site, cell niche establishment and promotion of mineralization. Successful completion of this project will transform bone graft technology for regeneration of complex bone defects from a frozen or freeze-dried allograft to a safe, infection-free, mechanically-stable, osteoinductive, and vasculogenic graft that is ultimately displaced by the patient's own tissue.

Relationships of muscle strength and bone mineral density in ambulatory children with cerebral palsy.

PubMed

Chen, C-L; Lin, K-C; Wu, C-Y; Ke, J-Y; Wang, C-J; Chen, C-Y

2012-02-01

This work explores the relationships of muscle strength and areal bone mineral density (aBMD) in ambulatory children with cerebral palsy (CP). The knee extensor strength, but not motor function, was related to aBMD. Thus, muscle strength, especially antigravity muscle strength, was more associated with aBMD in these children than motor function. Muscle strength is related to bone density in normal children. However, no studies have examined these relationships in ambulatory children with CP. This work explores the relationships of muscle strength and aBMD in ambulatory children with CP. Forty-eight ambulatory children with spastic CP, aged 5-15 years, were classified into two groups based on Gross Motor Function Classification System levels: I (n = 28) and II (n = 20). Another 31 normal development (ND) children were recruited as the comparison group for the aBMD. Children with CP underwent assessments of growth, lumbar and distal femur aBMD, Gross Motor Function Measure-66 (GMFM-66), and muscle strength of knee extensor and flexor by isokinetic dynamometer. The distal femur aBMD, but not lumbar aBMD, was lower in children with CP than in ND children (p < 0.05). Children with level I had greater knee flexor strength and GMFM-66 scores than those with level II (p < 0.001). However, the knee extensor strength and distal femur and lumbar aBMD did not differ between two groups. Regression analysis revealed the weight and knee extensor strength, but not GMFM-66 scores, were related positively to the distal femur and lumbar aBMD (adjusted r (2) = 0.56-0.65, p < 0.001). These results suggest the muscle strength, especially antigravity muscle strength, were more associated with the bone density of ambulatory children with CP than motor function. The data may allow clinicians for early identifying the ambulatory CP children of potential low bone density.

Theoretical effects of fully ductile versus fully brittle behaviors of bone tissue on the strength of the human proximal femur and vertebral body.

PubMed

Nawathe, Shashank; Yang, Haisheng; Fields, Aaron J; Bouxsein, Mary L; Keaveny, Tony M

2015-05-01

The influence of the ductility of bone tissue on whole-bone strength represents a fundamental issue of multi-scale biomechanics. To gain insight, we performed a computational study of 16 human proximal femurs and 12 T9 vertebral bodies, comparing the whole-bone strength for the two hypothetical bounding cases of fully brittle versus fully ductile tissue-level failure behaviors, all other factors, including tissue-level elastic modulus and yield stress, held fixed. For each bone, a finite element model was generated (60-82 μm element size; up to 120 million elements) and was virtually loaded in habitual (stance for femur, compression for vertebra) and non-habitual (sideways fall, only for femur) loading modes. Using a geometrically and materially non-linear model, the tissue was assumed to be either fully brittle or fully ductile. We found that, under habitual loading, changing the tissue behavior from fully ductile to fully brittle reduced whole-bone strength by 38.3±2.4% (mean±SD) and 39.4±1.9% for the femur and vertebra, respectively (p=0.39 for site difference). These reductions were remarkably uniform across bones, but (for the femur) were greater for non-habitual (57.1±4.7%) than habitual loading (p<0.001). At overall structural failure, there was 5-10-fold less failed tissue for the fully brittle than fully ductile cases. These theoretical results suggest that the whole-bone strength of the proximal femur and vertebra can vary substantially between fully brittle and fully ductile tissue-level behaviors, an effect that is relatively insensitive to bone morphology but greater for non-habitual loading. Copyright © 2015 Elsevier Ltd. All rights reserved.

Guided bone augmentation using ceramic space-maintaining devices: the impact of chemistry

PubMed Central

Anderud, Jonas; Abrahamsson, Peter; Jimbo, Ryo; Isaksson, Sten; Adolfsson, Erik; Malmström, Johan; Naito, Yoshihito; Wennerberg, Ann

2015-01-01

The purpose of the study was to evaluate histologically, whether vertical bone augmentation can be achieved using a hollow ceramic space maintaining device in a rabbit calvaria model. Furthermore, the chemistry of microporous hydroxyapatite and zirconia were tested to determine which of these two ceramics are most suitable for guided bone generation. 24 hollow domes in two different ceramic materials were placed subperiosteal on rabbit skull bone. The rabbits were sacrificed after 12 weeks and the histology results were analyzed regarding bone-to-material contact and volume of newly formed bone. The results suggest that the effect of the microporous structure of hydroxyapatite seems to facilitate for the bone cells to adhere to the material and that zirconia enhance a slightly larger volume of newly formed bone. In conclusion, the results of the current study demonstrated that ceramic space maintaining devices permits new bone formation and osteoconduction within the dome. PMID:25792855

Alterations of bone microstructure and strength in end-stage renal failure.

PubMed

Trombetti, A; Stoermann, C; Chevalley, T; Van Rietbergen, B; Herrmann, F R; Martin, P-Y; Rizzoli, R

2013-05-01

End-stage renal disease (ESRD) patients have a high risk of fractures. We evaluated bone microstructure and finite-element analysis-estimated strength and stiffness in patients with ESRD by high-resolution peripheral computed tomography. We observed an alteration of cortical and trabecular bone microstructure and of bone strength and stiffness in ESRD patients. Fragility fractures are common in ESRD patients on dialysis. Alterations of bone microstructure contribute to skeletal fragility, independently of areal bone mineral density. We compared microstructure and finite-element analysis estimates of strength and stiffness by high-resolution peripheral quantitative computed tomography (HR-pQCT) in 33 ESRD patients on dialysis (17 females and 16 males; mean age, 47.0 ± 12.6 years) and 33 age-matched healthy controls. Dialyzed women had lower radius and tibia cortical density with higher radius cortical porosity and lower tibia cortical thickness, compared to controls. Radius trabecular number was lower with higher heterogeneity of the trabecular network. Male patients displayed only a lower radius cortical density. Radius and tibia cortical thickness correlated negatively with bone-specific alkaline phosphatase (BALP). Microstructure did not correlate with parathyroid hormone (PTH) levels. Cortical porosity correlated positively with "Kidney Disease: Improving Global Outcomes" working group PTH level categories (r = 0.36, p < 0.04). BMI correlated positively with trabecular number (r = 0.4, p < 0.02) and negatively with trabecular spacing (r = -0.37, p < 0.03) and trabecular network heterogeneity (r = -0.4, p < 0.02). Biomechanics positively correlated with BMI and negatively with BALP. Cortical and trabecular bone microstructure and calculated bone strength are altered in ESRD patients, predominantly in women. Bone microstructure and biomechanical assessment by HR-pQCT may be of major clinical relevance in the evaluation of bone fragility in ESRD patients.

Serum markers of bone turnover are increased by modest weight loss with or without weight-bearing exercise in overweight premenopausal women.

PubMed

Rector, R Scott; Loethen, Joanne; Ruebel, Meghan; Thomas, Tom R; Hinton, Pamela S

2009-10-01

Weight loss improves metabolic fitness and reduces morbidity and mortality; however, weight reduction also reduces bone mineral density (BMD) and increases bone turnover. Weight-bearing aerobic exercise may preserve bone mass and maintain normal bone turnover during weight reduction. We investigated the impact of weight-bearing and nonweight-bearing exercise on serum markers of bone formation and breakdown during short-term, modest weight loss in overweight premenopausal women. Subjects (n = 36) were assigned to 1 of 3 weight-loss interventions designed to produce a 5% reduction in body weight over 6 weeks: (i) energy restriction only (n = 11; DIET); (ii) energy restriction plus nonweight-bearing exercise (n = 12, CYCLE); or (iii) energy restriction plus weight-bearing exercise (n = 13, RUN). Bone turnover markers were measured in serum collected at baseline and after weight loss. All groups achieved a ~5% reduction in body weight (DIET = 5.2%; CYCLE = 5.0%; RUN = 4.7%). Osteocalcin (OC) and C-terminal telopeptide of type I collagen (CTX) increased with weight loss in all 3 groups (p < 0.05), whereas bone alkaline phosphatase was unaltered by the weight-loss interventions. At baseline, OC and CTX were positively correlated (r = 0.36, p = 0.03), but the strength of this association was diminished (r = 0.30, p = 0.06) after weight loss. Modest weight loss, regardless of method, resulted in a significant increase in both OC and CTX. Low-impact, weight-bearing exercise had no effect on serum markers of bone formation or resorption in premenopausal women during weight loss. Future studies that examine the effects of high-impact, weight-bearing activity on bone turnover and BMD during weight loss are warranted.

Lactation-Induced Changes in the Volume of Osteocyte Lacunar-Canalicular Space Alter Mechanical Properties in Cortical Bone Tissue.

PubMed

Kaya, Serra; Basta-Pljakic, Jelena; Seref-Ferlengez, Zeynep; Majeska, Robert J; Cardoso, Luis; Bromage, Timothy G; Zhang, Qihong; Flach, Carol R; Mendelsohn, Richard; Yakar, Shoshana; Fritton, Susannah P; Schaffler, Mitchell B

2017-04-01

Osteocytes can remove and remodel small amounts of their surrounding bone matrix through osteocytic osteolysis, which results in increased volume occupied by lacunar and canalicular space (LCS). It is well established that cortical bone stiffness and strength are strongly and inversely correlated with vascular porosity, but whether changes in LCS volume caused by osteocytic osteolysis are large enough to affect bone mechanical properties is not known. In the current studies we tested the hypotheses that (1) lactation and postlactation recovery in mice alter the elastic modulus of bone tissue, and (2) such local changes in mechanical properties are related predominantly to alterations in lacunar and canalicular volume rather than bone matrix composition. Mechanical testing was performed using microindentation to measure modulus in regions containing solely osteocytes and no vascular porosity. Lactation caused a significant (∼13%) reduction in bone tissue-level elastic modulus (p < 0.001). After 1 week postweaning (recovery), bone modulus levels returned to control levels and did not change further after 4 weeks of recovery. LCS porosity tracked inversely with changes in cortical bone modulus. Lacunar and canalicular void space increased 7% and 15% with lactation, respectively (p < 0.05), then returned to control levels at 1 week after weaning. Neither bone mineralization (assessed by high-resolution backscattered scanning electron microscopy) nor mineral/matrix ratio or crystallinity (assessed by Raman microspectroscopy) changed with lactation. Thus, changes in bone mechanical properties induced by lactation and recovery appear to depend predominantly on changes in osteocyte LCS dimensions. Moreover, this study demonstrates that tissue-level cortical bone mechanical properties are rapidly and reversibly modulated by osteocytes in response to physiological challenge. These data point to a hitherto unappreciated role for osteocytes in modulating and maintaining local bone mechanical properties. © 2016 American Society for Bone and Mineral Research. © 2016 American Society for Bone and Mineral Research.

Impaired rib bone mass and quality in end-stage cystic fibrosis patients.

PubMed

Mailhot, Geneviève; Dion, Natalie; Farlay, Delphine; Rizzo, Sébastien; Bureau, Nathalie J; Jomphe, Valérie; Sankhe, Safiétou; Boivin, Georges; Lands, Larry C; Ferraro, Pasquale; Ste-Marie, Louis-Georges

2017-05-01

Advancements in research and clinical care have considerably extended the life expectancy of cystic fibrosis (CF) patients. However, with this extended survival come comorbidities. One of the leading co-morbidities is CF-related bone disease (CFBD), which progresses with disease severity and places patients at high risk for fractures, particularly of the ribs and vertebrae. Evidence that CF patients with vertebral fractures had higher bone mineral density (BMD) than the nonfracture group led us to postulate that bone quality is impaired in these patients. We therefore examined rib specimens resected at the time of lung transplant in CF patients to measure parameters of bone quantity and quality. In this exploratory study, we analysed 19 end-stage CF and 13 control rib specimens resected from otherwise healthy lung donors. BMD, bone microarchitecture, static parameters of bone formation and resorption and microcrack density of rib specimens were quantified by imaging, histomorphometric and histological methods. Variables reflecting the mineralization of ribs were assessed by digitized microradiography. The degree of bone mineralization (g/cm 3 ) and the heterogeneity index of the mineralization (g/cm 3 ) were calculated for trabecular and cortical bone. Compared to controls, CF ribs exhibited lower areal and trabecular volumetric BMD, decreased trabecular thickness and osteoid parameters, and increased microcrack density, that was particularly pronounced in specimens from patients with CF-related diabetes. Static parameters of bone resorption were similar in both groups. Degree of mineralization of total bone, but not heterogeneity index, was increased in CF specimens. The combination of reduced bone mass, altered microarchitecture, imbalanced bone remodeling (maintained bone resorption but decreased formation), increased microdamage and a small increase of the degree of mineralization, may lead to decreased bone strength, which, when coupled with chronic coughing and chest physical therapy, may provide an explanation for the increased incidence of rib fractures previously reported in this population. Copyright © 2017 Elsevier Inc. All rights reserved.

Strontium ranelate: a novel mode of action leading to renewed bone quality.

PubMed

Ammann, Patrick

2005-01-01

Various bone resorption inhibitors and bone stimulators have been shown to decrease the risk of osteoporotic fractures. However, there is still a need for agents promoting bone formation by inducing positive uncoupling between bone formation and bone resorption. In vitro studies have suggested that strontium ranelate enhances osteoblast cell replication and activity. Simultaneously, strontium ranelate dose-dependently inhibits osteoclast activity. In vivo studies indicate that strontium ranelate stimulates bone formation and inhibits bone resorption and prevents bone loss and/or promotes bone gain. This positive uncoupling between bone formation and bone resorption results in bone gain and improvement in bone geometry and microarchitecture, without affecting the intrinsic bone tissue quality. Thus, all the determinants of bone strength are positively influenced. In conclusion, strontium ranelate, a new treatment of postmenopausal osteoporosis, acts through an innovative mode of action, both stimulating bone formation and inhibiting bone resorption, resulting in the rebalancing of bone turnover in favor of bone formation. Strontium ranelate increases bone mass while preserving the bone mineralization process, resulting in improvement in bone strength and bone quality.

Mechanical strength of ceramic scaffolds reinforced with biopolymers is comparable to that of human bone.

PubMed

Henriksen, S S; Ding, M; Juhl, M Vinther; Theilgaard, N; Overgaard, S

2011-05-01

Eight groups of calcium-phosphate scaffolds for bone implantation were prepared of which seven were reinforced with biopolymers, poly lactic acid (PLA) or hyaluronic acid in different concentrations in order to increase the mechanical strength, without significantly impairing the microarchitecture. Controls were un-reinforced calcium-phosphate scaffolds. Microarchitectural properties were quantified using micro-CT scanning. Mechanical properties were evaluated by destructive compression testing. Results showed that adding 10 or 15% PLA to the scaffold significantly increased the mechanical strength. The increase in mechanical strength was seen as a result of increased scaffold thickness and changes to plate-like structure. However, the porosity was significantly lowered as a consequence of adding 15% PLA, whereas adding 10% PLA had no significant effect on porosity. Hyaluronic acid had no significant effect on mechanical strength. The novel composite scaffold is comparable to that of human bone which may be suitable for transplantation in specific weight-bearing situations, such as long bone repair.

Differential Bone Loss in Mouse Models of Colon Cancer Cachexia

PubMed Central

Bonetto, Andrea; Kays, Joshua K.; Parker, Valorie A.; Matthews, Ryan R.; Barreto, Rafael; Puppa, Melissa J.; Kang, Kyung S.; Carson, James A.; Guise, Theresa A.; Mohammad, Khalid S.; Robling, Alexander G.; Couch, Marion E.; Koniaris, Leonidas G.; Zimmers, Teresa A.

2017-01-01

Cachexia is a distinctive feature of colorectal cancer associated with body weight loss and progressive muscle wasting. Several mechanisms responsible for muscle and fat wasting have been identified, however it is not known whether the physiologic and molecular crosstalk between muscle and bone tissue may also contribute to the cachectic phenotype in cancer patients. The purpose of this study was to clarify whether tumor growth associates with bone loss using several experimental models of colorectal cancer cachexia, namely C26, HT-29, and ApcMin/+. The effects of cachexia on bone structure and strength were evaluated with dual energy X-ray absorptiometry (DXA), micro computed tomography (μCT), and three-point bending test. We found that all models showed tumor growth consistent with severe cachexia. While muscle wasting in C26 hosts was accompanied by moderate bone depletion, no loss of bone strength was observed. However, HT-29 tumor bearing mice showed bone abnormalities including significant reductions in whole-body bone mineral density (BMD), bone mineral content (BMC), femoral trabecular bone volume fraction (BV/TV), trabecular number (Tb.N), and trabecular thickness (Tb.Th), but no declines in strength. Similarly, cachexia in the ApcMin/+ mice was associated with significant decreases in BMD, BMC, BV/TV, Tb.N, and Tb.Th as well as decreased strength. Our data suggest that colorectal cancer is associated with muscle wasting and may be accompanied by bone loss dependent upon tumor type, burden, stage and duration of the disease. It is clear that preserving muscle mass promotes survival in cancer cachexia. Future studies will determine whether strategies aimed at preventing bone loss can also improve outcomes and survival in colorectal cancer cachexia. PMID:28123369

Differential Bone Loss in Mouse Models of Colon Cancer Cachexia.

PubMed

Bonetto, Andrea; Kays, Joshua K; Parker, Valorie A; Matthews, Ryan R; Barreto, Rafael; Puppa, Melissa J; Kang, Kyung S; Carson, James A; Guise, Theresa A; Mohammad, Khalid S; Robling, Alexander G; Couch, Marion E; Koniaris, Leonidas G; Zimmers, Teresa A

2016-01-01

Cachexia is a distinctive feature of colorectal cancer associated with body weight loss and progressive muscle wasting. Several mechanisms responsible for muscle and fat wasting have been identified, however it is not known whether the physiologic and molecular crosstalk between muscle and bone tissue may also contribute to the cachectic phenotype in cancer patients. The purpose of this study was to clarify whether tumor growth associates with bone loss using several experimental models of colorectal cancer cachexia, namely C26, HT-29, and Apc Min/+ . The effects of cachexia on bone structure and strength were evaluated with dual energy X-ray absorptiometry (DXA), micro computed tomography (μCT), and three-point bending test. We found that all models showed tumor growth consistent with severe cachexia. While muscle wasting in C26 hosts was accompanied by moderate bone depletion, no loss of bone strength was observed. However, HT-29 tumor bearing mice showed bone abnormalities including significant reductions in whole-body bone mineral density (BMD), bone mineral content (BMC), femoral trabecular bone volume fraction (BV/TV), trabecular number (Tb.N), and trabecular thickness (Tb.Th), but no declines in strength. Similarly, cachexia in the Apc Min/+ mice was associated with significant decreases in BMD, BMC, BV/TV, Tb.N, and Tb.Th as well as decreased strength. Our data suggest that colorectal cancer is associated with muscle wasting and may be accompanied by bone loss dependent upon tumor type, burden, stage and duration of the disease. It is clear that preserving muscle mass promotes survival in cancer cachexia. Future studies will determine whether strategies aimed at preventing bone loss can also improve outcomes and survival in colorectal cancer cachexia.

Targeting the LRP5 pathway improves bone properties in a mouse model of osteogenesis imperfecta.

PubMed

Jacobsen, Christina M; Barber, Lauren A; Ayturk, Ugur M; Roberts, Heather J; Deal, Lauren E; Schwartz, Marissa A; Weis, MaryAnn; Eyre, David; Zurakowski, David; Robling, Alexander G; Warman, Matthew L

2014-10-01

The cell surface receptor low-density lipoprotein receptor-related protein 5 (LRP5) is a key regulator of bone mass and bone strength. Heterozygous missense mutations in LRP5 cause autosomal dominant high bone mass (HBM) in humans by reducing binding to LRP5 by endogenous inhibitors, such as sclerostin (SOST). Mice heterozygous for a knockin allele (Lrp5(p.A214V) ) that is orthologous to a human HBM-causing mutation have increased bone mass and strength. Osteogenesis imperfecta (OI) is a skeletal fragility disorder predominantly caused by mutations that affect type I collagen. We tested whether the LRP5 pathway can be used to improve bone properties in animal models of OI. First, we mated Lrp5(+/p.A214V) mice to Col1a2(+/p.G610C) mice, which model human type IV OI. We found that Col1a2(+/p.G610C) ;Lrp5(+/p.A214V) offspring had significantly increased bone mass and strength compared to Col1a2(+/p.G610C) ;Lrp5(+/+) littermates. The improved bone properties were not a result of altered mRNA expression of type I collagen or its chaperones, nor were they due to changes in mutant type I collagen secretion. Second, we treated Col1a2(+/p.G610C) mice with a monoclonal antibody that inhibits sclerostin activity (Scl-Ab). We found that antibody-treated mice had significantly increased bone mass and strength compared to vehicle-treated littermates. These findings indicate increasing bone formation, even without altering bone collagen composition, may benefit patients with OI. © 2014 American Society for Bone and Mineral Research.

Contributions of fat mass and fat distribution to hip bone strength in healthy postmenopausal Chinese women.

PubMed

Shao, Hong Da; Li, Guan Wu; Liu, Yong; Qiu, Yu You; Yao, Jian Hua; Tang, Guang Yu

2015-09-01

The fat and bone connection is complicated, and the effect of adipose tissue on hip bone strength remains unclear. The aim of this study was to clarify the relative contribution of body fat accumulation and fat distribution to the determination of proximal femur strength in healthy postmenopausal Chinese women. This cross-sectional study enrolled 528 healthy postmenopausal women without medication history or known diseases. Total lean mass (LM), appendicular LM (ALM), percentage of lean mass (PLM), total fat mass (FM), appendicular FM (AFM), percentage of body fat (PBF), android and gynoid fat amount, android-to-gynoid fat ratio (AOI), bone mineral density (BMD), and proximal femur geometry were measured by dual energy X-ray absorptiometry. Hip structure analysis was used to compute some variables as geometric strength-related parameters by analyzing the images of the hip generated from DXA scans. Correlation analyses among anthropometrics, variables of body composition and bone mass, and geometric indices of hip bone strength were performed with stepwise linear regression analyses as well as Pearson's correlation analysis. In univariate analysis, there were significantly inverse correlations between age, years since menopause (YSM), hip BMD, and hip geometric parameters. Bone data were positively related to height, body weight, LM, ALM, FM, AFM, and PBF but negatively related to AOI and amount of android fat (all P < 0.05). AFM and AOI were significantly related to most anthropometric parameters. AFM was positively associated with height, body weight, and BMI. AFM was negatively associated with age and YSM. AOI was negatively associated with height, body weight, and BMI. AOI positively associated with age and YSM. LM, ALM, and FM had a positive relationship with anthropometric parameters (P < 0.05 for all). PLM had a negative relationship with those parameters. The correlation between LM, ALM, FM, PLM, ALM, age, and YSM was not significant. In multivariate linear regression analysis, the hip bone strength was observed to have a consistent and unchanged positive association with AFM and a negative association with AOI, whereas its association with other variables of body composition was not significant after adjusting for age, years since menopause, height, body weight, and BMI. AFM may be a positively protective effect for hip bone strength while AOI, rather than android fat, shows a strong negative association with hip bone strength after making an adjustment for confounders (age, YSM, height, body weight, and BMI) in healthy postmenopausal Chinese women. Rational weight control and AOI reduction during menopause may have vital clinical significance in decreasing postmenopausal osteoporosis.

The effects of honey (Apis dorsata) supplements on increased bone strength in ovariectomized rat as animal model of osteoporosis

NASA Astrophysics Data System (ADS)

Yudaniayanti, Ira Sari; Primarizky, Hardany; Nangoi, Lianny

2018-04-01

Osteoporosis is a chronic skeletal disease characterized by low bone mass and microarchitectural deterioration with a consequent increase in bone fragility and fracture risk. The aim of the study was to evaluate the effects of honey (Apis dorsata) supplements on increased bone strength in ovariectomized rat as animal models of osteoporosis. Twenty female rats at 3 months of age, weighing 150-200 g were used in the study. The rats were divided into five groups (n=4) : Sham operation group (SH); ovariectomy group no treatment(OVX); ovariectomy with treatment Apis dorsata 1g/Kg BW (AD-1); ovariectomy with treatment Apis dorsata 2g/Kg BW (AD-2); ovariectomy with treatment Apis dorsata 4g/Kg BW (AD-3). The treatment started to be given the next day after ovariectomy operation for 12 weeks. The Rats were sacrified within 12 weeks, and then the right femur were taken bone strength test. Based on the statistical analysis of the bone strength test, the greatest score belongs to the Sham operation group (SH) that have significant difference (p<0.05) with OVX group and AD-1 group, but there was no significant difference with AD-2 and AD-3 (p>0,05). In conclusion, honey (Apis dorsata) supplements has the effect of increasing bone strength in ovariectomized rat as animal models of osteoporosis, so that honey (Apis dorsata) supplements has the potential to be used as an alternative treatment for osteoporosis.

Insights into the effects of tensile and compressive loadings on human femur bone.

PubMed

Havaldar, Raviraj; Pilli, S C; Putti, B B

2014-01-01

Fragile fractures are most likely manifestations of fatigue damage that develop under repetitive loading conditions. Numerous microcracks disperse throughout the bone with the tensile and compressive loads. In this study, tensile and compressive load tests are performed on specimens of both the genders within 19 to 83 years of age and the failure strength is estimated. Fifty five human femur cortical samples are tested. They are divided into various age groups ranging from 19-83 years. Mechanical tests are performed on an Instron 3366 universal testing machine, according to American Society for Testing and Materials International (ASTM) standards. The results show that stress induced in the bone tissue depends on age and gender. It is observed that both tensile and compression strengths reduces as age advances. Compressive strength is more than tensile strength in both the genders. The compression and tensile strength of human femur cortical bone is estimated for both male and female subjecting in the age group of 19-83 years. The fracture toughness increases till 35 years in male and 30 years in female and reduces there after. Mechanical properties of bone are age and gender dependent.

Skeletal assessment with finite element analysis: relevance, pitfalls and interpretation.

PubMed

Campbell, Graeme Michael; Glüer, Claus-C

2017-07-01

Finite element models simulate the mechanical response of bone under load, enabling noninvasive assessment of strength. Models generated from quantitative computed tomography (QCT) incorporate the geometry and spatial distribution of bone mineral density (BMD) to simulate physiological and traumatic loads as well as orthopaedic implant behaviour. The present review discusses the current strengths and weakness of finite element models for application to skeletal biomechanics. In cadaver studies, finite element models provide better estimations of strength compared to BMD. Data from clinical studies are encouraging; however, the superiority of finite element models over BMD measures for fracture prediction has not been shown conclusively, and may be sex and site dependent. Therapeutic effects on bone strength are larger than for BMD; however, model validation has only been performed on untreated bone. High-resolution modalities and novel image processing methods may enhance the structural representation and predictive ability. Despite extensive use of finite element models to study orthopaedic implant stability, accurate simulation of the bone-implant interface and fracture progression remains a significant challenge. Skeletal finite element models provide noninvasive assessments of strength and implant stability. Improved structural representation and implant surface interaction may enable more accurate models of fragility in the future.

Maintaining Restored Bone with Bisphoshonate in the Ovariectomized Rat Skeleton: Dynamic Histomorphometry of Changes in Bone Mass

NASA Technical Reports Server (NTRS)

Jee, W. S. S.; Tang, L.; Ke, H. Z.; Setterberg, R. B.; Kimmel, D. B.

1993-01-01

This experiment contains the crucial data for the Lose, Restore and Maintain (LRM) concept, a practical approach for reversing existing osteoporosis. The LRM concept uses ovariectomy (ox) to lose bone, an anabolic agent to restore bone mass and then switches to an anti-resorptive agent to maintain bone mass. We ox'd or sham-ox'd rats for 150 days (Loss Phase), treated them with 6 mg PGE2/kg/d for 75 days to restore lost cancellous bone mass (Restore Phase) and then stopped PGE2 treatment and began treatment with 1 or 5 micro-g/kg Risedronate, a bisphosphonate twice a week for 60 days (Maintain Phase). During the Loss Phase, cancellous bone volumes of the proximal tibial metaphysis (PTM) in the ox'd rat fell to 19% of initial controls. During the Restore Phase, the PTM bone volume in ox'd rats doubled. However, when PGE2 treatment was stopped, the PGE2-induced cancellous bone disappeared. In contrast, 5 micro-g of Risedronate inhibited the bone loss and maintained it at the PGE2 treatment level. The key dynamic histomorphometry value for the restore (R) and maintenance (M) phases was the ratio of bone formation to resorption rates. The ratio was elevated to 5.8 in the R phase and depressed to 0.4 for no and 1 micro-g Risedronate treated M phase and to a ratio of near unity of 1.1 for the 5 micro-g Risedronate treatment. These findings indicate that we were successful in maintaining the new PTM bone induced by PGE2 after discontinuing PGE2 by administering enough Risedronate, a resorption inhibitor. We concluded that the LRM concept is correct and such an approach should be considered when employing anabolic agents or growth factors in the treatment of osteoporosis. Continued use of an anabolic agent may not be appropriate because of cost, potential adverse side effects and a loss of efficacy.

Maintaining Restored Bone with Bisphosphonate in the Ovariectomized Rat Skeleton: Dynamic Histomorphometry of Changes in Bone Mass

NASA Technical Reports Server (NTRS)

Jee, W. S. S.; Tang, L.; Ke, H. Z.; Setterberg, R. B.; Kimmel, D. B.

1993-01-01

This experiment contains the crucial data for the Lose, Restore and Maintain (LRM) concept, a practical approach for reversing existing osteoporosis. The LRM concept uses ovariectomy (ox) to lose bone, an anabolic agent to restore bone mass and then switches to an antiresorptive agent to maintain bone mass. We ox'd or sham-ox'd rats for 150 days (Loss Phase), treated them with 6 mg PGE(sub 2)kg/d for 75 days to restore lost cancellous bone mass (Restore Phase) and then stopped PGE(sub 2) treatment and began treatment with 1 or 5 micrograms/kg Risedronate, a bisphosphonate twice a week for 60 days (Maintain Phase). During the Loss Phase, cancellous bone volumes of the Proximal Tibial Metaphysis (PTM) in the ox'd rat fell to 19% of initial controls. During the Restore Phase, the PTM bone volume in ox'd rats doubled. However, when PGE(sub 2) treatment was stopped, the PGE(sub 2)-induced cancellous bone disappeared. In contrast, 5 miligrams of Risedronate inhibited the bone loss and maintained it at the PGE(sub 2) treatment level. The key dynamic histomorphometry value for the Restore (R) and Maintenance (M) phases was the ratio of bone formation to resorption rates. The ratio was elevated to 5.8 in the R phase and depressed to 0.4 for no and 1 miligram Risedronate treated M phase and to a ratio of near unity of 1.1 for the 5miligrams Risedronate treatment. These findings indicate that we were successful in maintaining the new PTM bone induced by PGE(sub 2) after discontinuing PGE(sub 2) by administering enough Risedronate, a resorption inhibitor. We concluded that the LRM concept is correct and such an approach should be considered when employing anabolic agents or growth factors in the treatment of osteoporosis. Continued use of an anabolic agent may not be appropriate because of cost, potential adverse side effects and a loss of efficacy.

Bone strength measured by peripheral quantitative computed tomography and the risk of nonvertebral fractures: the osteoporotic fractures in men (MrOS) study.

PubMed

Sheu, Yahtyng; Zmuda, Joseph M; Boudreau, Robert M; Petit, Moira A; Ensrud, Kristine E; Bauer, Douglas C; Gordon, Christopher L; Orwoll, Eric S; Cauley, Jane A

2011-01-01

Many fractures occur in individuals without osteoporosis defined by areal bone mineral density (aBMD). Inclusion of other aspects of skeletal strength may be useful in identifying at-risk subjects. We used surrogate measures of bone strength at the radius and tibia measured by peripheral quantitative computed tomography (pQCT) to evaluate their relationships with nonvertebral fracture risk. Femoral neck (FN) aBMD, measured by dual-energy X-ray absorptiometry (DXA), also was included. The study population consisted of 1143 white men aged 69+ years with pQCT measures at the radius and tibia from the Minneapolis and Pittsburgh centers of the Osteoporotic Fractures in Men (MrOS) study. Principal-components analysis and Cox proportional-hazards modeling were used to identify 21 of 58 pQCT variables with a major contribution to nonvertebral incident fractures. After a mean 2.9 years of follow-up, 39 fractures occurred. Men without incident fractures had significantly greater bone mineral content, cross-sectional area, and indices of bone strength than those with fractures by pQCT. Every SD decrease in the 18 of 21 pQCT parameters was significantly associated with increased fracture risk (hazard ration ranged from 1.4 to 2.2) independent of age, study site, body mass index (BMI), and FN aBMD. Using area under the receiver operation characteristics curve (AUC), the combination of FN aBMD and three radius strength parameters individually increased fracture prediction over FN aBMD alone (AUC increased from 0.73 to 0.80). Peripheral bone strength measures are associated with fracture risk and may improve our ability to identify older men at high risk of fracture. © 2011 American Society for Bone and Mineral Research.

Creation of bioactive glass (13-93) scaffolds for structural bone repair using a combined finite element modeling and rapid prototyping approach.

PubMed

Xiao, Wei; Zaeem, Mohsen Asle; Bal, B Sonny; Rahaman, Mohamed N

2016-11-01

There is a clinical need for synthetic bioactive materials that can reliably repair intercalary skeletal tissue loss in load-bearing bones. Bioactive glasses have been investigated as one such material but their mechanical response has been a concern. Previously, we created bioactive silicate glass (13-93) scaffolds with a uniform grid-like microstructure which showed a compressive strength comparable to human cortical bone but a much lower flexural strength. In the present study, finite element modeling (FEM) was used to re-design the scaffold microstructure to improve its flexural strength without significantly lowering its compressive strength and ability to support bone infiltration in vivo. Then scaffolds with the requisite microstructures were created by a robotic deposition method and tested in four-point bending and compression to validate the FEM simulations. In general, the data validated the predictions of the FEM simulations. Scaffolds with a porosity gradient, composed of a less porous outer region and a more porous inner region, showed a flexural strength (34±5MPa) that was more than twice the value for the uniform grid-like microstructure (15±5MPa) and a higher compressive strength (88±20MPa) than the grid-like microstructure (72±10MPa). Upon implantation of the scaffolds for 12weeks in rat calvarial defects in vivo, the amount of new bone that infiltrated the pore space of the scaffolds with the porosity gradient (37±16%) was similar to that for the grid-like scaffolds (35±6%). These scaffolds with a porosity gradient that better mimics the microstructure of human long bone could provide more reliable implants for structural bone repair. Copyright © 2016 Elsevier B.V. All rights reserved.

The effect of bone tunnel dilation versus extraction drilling on the initial fixation strength of press-fit anterior cruciate ligament reconstruction.

PubMed

Dargel, Jens; Schmidt-Wiethoff, Rüdiger; Brüggemann, Gert-Peter; Koebke, Jürgen

2007-11-01

Serial dilation of the bone tunnel has been reported to create a tighter graft-tunnel fit. It was hypothesized that a serial dilation of the femoral bone tunnel would increase the initial fixation strength in press-fit anterior cruciate ligament (ACL) reconstructive surgery. Initial fixation strength of the femoral press-fit fixation technique was investigated in 72 porcine specimens in an ex vivo study by varying the femoral tunnel preparation technique. Extraction-drilling, tunnel dilation by 1 mm and dilation by 2.5 mm were assessed. Initial fixation strength of press-fit fixated patellar tendon-bone grafts was tested within each preparation group conducting a single cycle (and cyclic) load to failure protocol. The resulting tunnel diameter and the porcine femoral bone mineral density were determined using microradiographs and peripheral quantitative CT scans, respectively. Dilating a previously extraction-drilled femoral bone tunnel by 1 mm significantly enhances initial press-fit fixation strength in both single cycle and cyclic load to failure testing when compared to extraction-drilling and tunnel dilation by 2.5 mm. Due to an initial spring-back effect the resulting diameter of the femoral tunnel was underestimated by 3.3% with drilling and 6.7 and 12.2% with dilation by 1 and 2.5 mm, respectively. Volumetric trabecular bone mineral density at the site corresponding to the area of tunnel placement averaged 318 mg/cm(3). Dilating a femoral tunnel that is underdrilled by 1 mm appears to be a reasonable technical procedure in order to enhance initial fixation strength of press-fit ACL graft fixation.

Ductile sliding between mineral crystals followed by rupture of collagen crosslinks: experimentally supported micromechanical explanation of bone strength.

PubMed

Fritsch, Andreas; Hellmich, Christian; Dormieux, Luc

2009-09-21

There is an ongoing discussion on how bone strength could be explained from its internal structure and composition. Reviewing recent experimental and molecular dynamics studies, we here propose a new vision on bone material failure: mutual ductile sliding of hydroxyapatite mineral crystals along layered water films is followed by rupture of collagen crosslinks. In order to cast this vision into a mathematical form, a multiscale continuum micromechanics theory for upscaling of elastoplastic properties is developed, based on the concept of concentration and influence tensors for eigenstressed microheterogeneous materials. The model reflects bone's hierarchical organization, in terms of representative volume elements for cortical bone, for extravascular and extracellular bone material, for mineralized fibrils and the extrafibrillar space, and for wet collagen. In order to get access to the stress states at the interfaces between crystals, the extrafibrillar mineral is resolved into an infinite amount of cylindrical material phases oriented in all directions in space. The multiscale micromechanics model is shown to be able to satisfactorily predict the strength characteristics of different bones from different species, on the basis of their mineral/collagen content, their intercrystalline, intermolecular, lacunar, and vascular porosities, and the elastic and strength properties of hydroxyapatite and (molecular) collagen.

The Soy Isoflavones for Reducing Bone Loss (SIRBL) Study: Three year effects on pQCT bone mineral density and strength measures in postmenopausal women

PubMed Central

SHEDD-WISE, KRISTINE M.; ALEKEL, D. LEE; HOFMANN, HEIKE; HANSON, KATHY B.; SCHIFERL, DAN J.; HANSON, LAURA N.; VAN LOAN, MARTA D.

2011-01-01

Soy isoflavones exert inconsistent bone density-preserving effects, but the bone strength-preserving effects in humans are unknown. Our double-blind randomized controlled trial examined two soy isoflavone doses (80 or 120 mg/d) vs placebo tablets on volumetric bone mineral density (vBMD) and strength (via peripheral quantitative computed tomography) in healthy postmenopausal women (46–63 y). We measured 3 y change in cortical (Ct) BMD, cortical thickness (CtThk), periosteal circumference (PC), endosteal circumference (EC), and strength-strain index (SSI) at 1/3 midshaft femur (N=171) and trabecular (Tb) BMD, PC, and SSI at 4% distal tibia (N=162). We found no treatment effect on femur CtThk, PC, or EC, or tibia TbBMD or PC. Strongest predictors (negative) of tibia TbBMD and SSI and femur CtBMD were timepoint and bone resorption; whole body fat mass was protective of SSI. As time since last menstrual period (TLMP) increased (p=0.012), 120 mg/d was protective of CtBMD. Strongest predictors of femur SSI were timepoint, bone resorption, and TLMP (protective). Isoflavone tablets were negative predictors of SSI, but 80 mg/d became protective as bone turnover increased (p=0.011). Soy isoflavone treatment for 3 y was modestly beneficial for midshaft femur vBMD as TLMP increased, and for midshaft femur SSI as bone turnover increased. PMID:21295742

The effect of CHA-doped Sr addition to the mechanical strength of metakaolin dental implant geopolymer composite

NASA Astrophysics Data System (ADS)

Sunendar, Bambang; Fathina, Afiya; Harmaji, Andrie; Mardhian, Deby Fajar; Asri, Lia; Widodo, Haris Budi

2017-09-01

The prospective material for implant plate required sufficient mechanical properties to maintain fracture fixation and resist physiological stress until bone healing process finished. Various problem implant plate based on metal and polymer materials when used as fixation for bone defect case induced developmental of bioceramic for implant plate materials. Materials that now has been attract a lot of attention is carbonate apatite and strontium as doping which known to have good biocompability along with biointegrity and mechanical charateristics. Other materials that have been known to have good mechanical properties are metakaolin and use of chitosan as coupling agent. Metakaolin and carbonate apatite can be produced by sol-gel methode which simpler, economical and energy-saving procedure furthermore use of chitosan which is widely found in the nature of Indonesia can be used to encourage the utilization of natural resources. The aim fo this paper is to investigated effect of CHA-doped Sr 5 (%) mol addition to the mechanical strength of metakaolin dental implant geoploymer composite. In this paper metakaolin is used as geopolymerization precursors. The test results have shown that addition of filler of apatite carbonate doped 5% mol strontium can be said to increase the value of mechnical properties but high concentration of calcium in the nanocomposite also can complicate the equilibrium of the geopolymerization process and induce alkali aggregate reactivity (AAR). The sample group of nanocomposite of metakaolin and carbonate apatite-doped 5% mol strontium (2: 1% wt) with 2% chitosan as a coupling agent based on geopolymerization for implant plate application has the best mechanical properties among all sample groups but does not qualify as an implant plate on cortical bone but can be used for the application of the implant plate on the trabecular bone specifically and potentially as a bone initiator.

Vertebral and femoral bone mineral density and bone strength in prostate cancer patients assessed in phantomless PET/CT examinations.

PubMed

Schwaiger, Benedikt J; Kopperdahl, David L; Nardo, Lorenzo; Facchetti, Luca; Gersing, Alexandra S; Neumann, Jan; Lee, Kwang J; Keaveny, Tony M; Link, Thomas M

2017-08-01

Bone fracture risk assessed ancillary to positron emission tomography with computed tomography co-registration (PET/CT) could provide substantial clinical value to oncology patients with elevated fracture risk without introducing additional radiation dose. The purpose of our study was to investigate the feasibility of obtaining valid measurements of bone mineral density (BMD) and finite element analysis-derived bone strength of the hip and spine using PET/CT examinations of prostate cancer patients by comparing against values obtained using routine multidetector-row computed tomography (MDCT) scans-as validated in previous studies-as a reference standard. Men with prostate cancer (n=82, 71.6±8.3 years) underwent Fluorine-18 NaF PET/CT and routine MDCT within three months. Femoral neck and total hip areal BMD, vertebral trabecular BMD and femur and vertebral strength based on finite element analysis were assessed in 63 paired PET/CT and MDCT examinations using phantomless calibration and Biomechanical-CT analysis. Men with osteoporosis or fragile bone strength identified at either the hip or spine (vertebral trabecular BMD ≤80mg/cm 3 , femoral neck or total hip T-score ≤-2.5, vertebral strength ≤6500N and femoral strength ≤3500N, respectively) were considered to be at high risk of fracture. PET/CT- versus MDCT-based BMD and strength measurements were compared using paired t-tests, linear regression and by generating Bland-Altman plots. Agreement in fracture-risk classification was assessed in a contingency table. All measurements from PET/CT versus MDCT were strongly correlated (R 2 =0.93-0.97; P<0.0001 for all). Mean differences for total hip areal BMD (0.001g/cm 2 , 1.1%), femoral strength (-60N, 1.3%), vertebral trabecular BMD (2mg/cm 3 , 2.6%) and vertebral strength (150N; 1.7%) measurements were not statistically significant (P>0.05 for all), whereas the mean difference in femoral neck areal BMD measurements was small but significant (-0.018g/cm 2 ; -2.5%; P=0.007). The agreement between PET/CT and MDCT for fracture-risk classification was 97% (0.89 kappa for repeatability). Ancillary analyses of BMD, bone strength, and fracture risk agreed well between PET/CT and MDCT, suggesting that PET/CT can be used opportunistically to comprehensively assess bone integrity. In subjects with high fracture risk such as cancer patients this may serve as an additional clinical tool to guide therapy planning and prevention of fractures. Copyright © 2017 Elsevier Inc. All rights reserved.

Effects of mechanical loading on the degradability and mechanical properties of the nanocalcium-deficient hydroxyapatite–multi(amino acid) copolymer composite membrane tube for guided bone regeneration

PubMed Central

Duan, Hong; Yang, Hongsheng; Xiong, Yan; Zhang, Bin; Ren, Cheng; Min, Li; Zhang, Wenli; Yan, Yonggang; Li, Hong; Pei, Fuxing; Tu, Chongqi

2013-01-01

Background and methods Guided bone regeneration (GBR) is a new treatment for bone defects, and the property of membrane is critical to the success of GBR. This study focuses on a novel membrane tube for GBR, which was prepared by a nanocalcium-deficient hydroxyapatite–multi(amino acid) copolymer (n-CDHA-MAC) composite. The biomechanical strength and degradability of this membrane tube under mechanical loading after immersion in phosphate-buffered solution were investigated to evaluate the effects of mechanical loading on the membrane tube. The membrane-tube group with no mechanical loading and femora bone were used as controls. Results The compressive strength and bending strength of n-CDHA-MAC membrane tubes were 66.4 ± 10.2 MPa and 840.7 ± 12.1 MPa, which were lower than those of the goats’ femoral bones (69.0 ± 5.5 MPa and 900.2 ± 17.3 MPa), but there were no significant (P > 0.05) differences. In the in vitro degradability experiment, all membrane tubes were degradable and showed a surface-erosion degradation model. The PH of solution fluctuated from 7.2 to 7.5. The weight and mechanical strength of loaded tubes decreased more quickly than nonloaded ones, with significant differences (P < 0.05). However, the strength of the loaded group after degradation achieved 20.4 ± 1.2 MPa, which was greater than the maximum mechanical strength of 4.338 MPa based on goat femoral middle stationary state by three-dimensional finite-element analysis. Conclusions n-CDHA-MAC membrane tubes have good biomechanical strength during degradation under mechanical loading. Therefore, this membrane tube is an ideal GBR membrane for critical size defects of long bones in goats for animal experiments. PMID:23946651

X1: A Robotic Exoskeleton for In-Space Countermeasures and Dynamometry

NASA Technical Reports Server (NTRS)

Rea, Rochelle; Beck, Christopher; Rovekamp, Roger; Diftler, Myron; Neuhaus, Peter

2013-01-01

Bone density loss and muscle atrophy are among the National Aeronautics and Space Administration's (NASA) highest concerns for crew health in space. Countless hours are spent maintaining an exercise regimen aboard the International Space Station (ISS) to counteract the effect of zero-gravity. Looking toward the future, NASA researchers are developing new compact and innovative exercise technologies to maintain crew health as missions increase in length and take humans further out into the solar system. The X1 Exoskeleton, initially designed for assisted mobility on Earth, was quickly theorized to have far-reaching potential as both an in-space countermeasures device and a dynamometry device to measure muscle strength. This lower-extremity device has the ability to assist or resist human movement through the use of actuators positioned at the hips and knees. Multiple points of adjustment allow for a wide range of users, all the while maintaining correct joint alignment. This paper discusses how the X1 Exoskeleton may fit NASA's onorbit countermeasures needs.

Injectable biomaterials for minimally invasive orthopedic treatments.

PubMed

Jayabalan, M; Shalumon, K T; Mitha, M K

2009-06-01

Biodegradable and injectable hydroxy terminated-poly propylene fumarate (HT-PPF) bone cement was developed. The injectable formulation consisting HT-PPF and comonomer, n-vinyl pyrrolidone, calcium phosphate filler, free radical catalyst, accelerator and radiopaque agent sets rapidly to hard mass with low exothermic temperature. The candidate bone cement attains mechanical strength more than the required compressive strength of 5 MPa and compressive modulus 50 MPa. The candidate bone cement resin elicits cell adhesion and cytoplasmic spreading of osteoblast cells. The cured bone cement does not induce intracutaneous irritation and skin sensitization. The candidate bone cement is tissue compatible without eliciting any adverse tissue reactions. The candidate bone cement is osteoconductive and inductive and allow osteointegration and bone remodeling. HT-PPF bone cement is candidate bone cement for minimally invasive radiological procedures for the treatment of bone diseases and spinal compression fractures.

Comparison and preparation of multilayered polylactic acid fabric strengthen calcium phosphate-based bone substitutes for orthopedic applications.

PubMed

Chen, Wen-Cheng; Ko, Chia-Ling; Yang, Jia-Kai; Wu, Hui-Yu; Lin, Jia-Horng

2016-03-01

An attempt to maintain the three-dimensional space into restorative sites through the conveniently pack porous fillers are general used strategy. Advancement in the manufacturing protective shells in the scaffolds, which would be filled with brittle ceramic grafts for the development of highly connective pores provides the approach to solve crack problem for generating the tissues. Therefore, multilayered braided and alkalized poly(lactic acid) (PLA) composites with calcium phosphate bone cement (CPC) were synthesized and compared. The PLA/CPC composites were divided into various groups according to a series of heat-treatment temperatures (100-190 °C) and periods (1-3 h) and then characterized. The effects of 24-h immersion on the strength decay resistance of the samples were compared. Results showed that the residual oil capped on the surfaces of alkalized PLA braid was removed, and the structure was unaltered. However, the reduced tensile stress of alkalized PLA braids was due to ester-group formation by hydrolysis. Mechanical test results of PLA/CPC composites showed that the strength significantly increased after heat treatment, except when the heating temperature was higher than the PLA melting point at approximately 160-170 °C. The degree of PLA after recrystallization became higher than that of unheated composites, thereby leading to reduced strength and toughness of the specimen. Braiding fibers of biodegradable PLA reinforced and toughened the structure particularly of the extra-brittle material of thin-sheet CPC after implantation.

Rotary ultrasonic bone drilling: Improved pullout strength and reduced damage.

PubMed

Gupta, Vishal; Pandey, Pulak M; Silberschmidt, Vadim V

2017-03-01

Bone drilling is one of the most common operations used to repair fractured parts of bones. During a bone drilling process, microcracks are generated on the inner surface of the drilled holes that can detrimentally affect osteosynthesis and healing. This study focuses on the investigation of microcracks and pullout strength of cortical-bone screws in drilled holes. It compares conventional surgical bone drilling (CSBD) with rotary ultrasonic bone drilling (RUBD), a novel approach employing ultrasonic vibration with a diamond-coated hollow tool. Both techniques were used to drill holes in porcine bones in an in-vitro study. Scanning electron microscopy was used to observe microcracks and surface morphology. The results obtained showed a significant decrease in the number and dimensions of microcracks generated on the inner surface of drilled holes with the RUBD process in comparison to CSBD. It was also observed that a higher rotational speed and a lower feed rate resulted in lower damage, i.e. fewer microcracks. Biomechanical axial pullout strength of a cortical bone screw inserted into a hole drilled with RUBD was found to be much higher (55-385%) than that for CSBD. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

Vitamin K2 improves femoral bone strength without altering bone mineral density in gastrectomized rats.

PubMed

Iwamoto, Jun; Sato, Yoshihiro; Matsumoto, Hideo

2014-01-01

Gastrectomy (GX) induces osteopenia in rats. The present study examined the skeletal effects of vitamin K2 in GX rats. Thirty male Sprague-Dawley rats (12 wk old) were randomized by the stratified weight method into the following three groups of 10 animals each: sham operation (control) group; GX group; and GX+oral vitamin K2 (menatetrenone, 30 mg/kg, 5 d/wk) group. Treatment was initiated at 1 wk after surgery. After 6 wk of treatment, the bone mineral content (BMC), bone mineral density (BMD), and mechanical strength of the femoral diaphysis and distal metaphysis were determined by peripheral quantitative computed tomography and mechanical strength tests, respectively. GX induced decreases in the BMC, BMD, and ultimate force of the femoral diaphysis and distal metaphysis. Vitamin K2 did not significantly influence the BMC or BMD of the femoral diaphysis or distal metaphysis in GX rats, but attenuated the decrease in the ultimate force and increased the stiffness of the femoral diaphysis. The present study showed that administration of vitamin K2 to GX rats improved the bone strength of the femoral diaphysis without altering the BMC or BMD, suggesting effects of vitamin K2 on the cortical bone quality.

Sex-related differences of bone properties of pelvic limb and bone metabolism indices in 14-month-old ostriches (Struthio camelus).

PubMed

Krupski, W; Tatara, M R; Charuta, A; Brodzki, A; Szpetnar, M; Jóźwik, A; Strzałkowska, N; Poławska, E; Łuszczewska-Sierakowska, I

2018-06-01

1. Sex-related differences of long pelvic limb bones and serum bone metabolism indices were evaluated in 14-month-old female (N = 7) and male (N = 7) ostriches of similar body weights. 2. Densitometric parameters of femur, tibia and tarsometatarsus were determined using quantitative computed tomography (volumetric bone mineral density, calcium hydroxyapatite density and mean volumetric bone mineral density) and dual energy X-ray absorptiometry (bone mineral density and bone mineral content) methods. Geometrical parameters such as cortical bone area, cross-sectional area, second moment of inertia, mean relative wall thickness and cortical index were determined in the midshaft of bones. Mechanical properties of bones (maximum elastic strength and ultimate strength) were evaluated using three-point bending test. Serum concentrations of free amino acids, osteocalcin, N-terminal propeptide of type I procollagen, C-terminal telopeptides of type II collagen and total antioxidative capacity were also determined. 3. Bone weight and relative bone weight of all bones were significantly higher in males than in females. Significantly lower values of trabecular bone mineral density and calcium hydroxyapatite density were found in the trabecular bone of tibia in males. The highest number of the sex-related differences was observed in the tarsometatarsus where bone length, bone mineral content, cortical bone area, cross-sectional area and ultimate strength were higher in males. Serum concentrations of taurine, hydroxyproline, valine and isoleucine were significantly higher in males. 4. Higher loading of the tarsometatarsus in comparison to femur and tibia may be an important factor interacting with sex hormones in regulation of bone formation and mineralisation processes. Sex-related differences of bone properties were associated with increased serum concentration of selected amino acids in males.

Biomechanical monitoring of healing bone based on acoustic emission technology.

PubMed

Hirasawa, Yasusuke; Takai, Shinro; Kim, Wook-Cheol; Takenaka, Nobuyuki; Yoshino, Nobuyuki; Watanabe, Yoshinobu

2002-09-01

Acoustic emission testing is a well-established method for assessment of the mechanical integrity of general construction projects. The purpose of the current study was to investigate the usefulness of acoustic emission technology in monitoring the yield strength of healing callus during external fixation. Thirty-five patients with 39 long bones treated with external fixation were evaluated for fracture healing by monitoring load for the initiation of acoustic emission signal (yield strength) under axial loading. The major criteria for functional bone union based on acoustic emission testing were (1) no acoustic emission signal on full weightbearing, and (2) a higher estimated strength than body weight. The yield strength monitored by acoustic emission testing increased with the time of healing. The external fixator could be removed safely and successfully in 97% of the patients. Thus, the acoustic emission method has good potential as a reliable method for monitoring the mechanical status of healing bone.

Combined treatment with a transforming growth factor beta inhibitor (1D11) and bortezomib improves bone architecture in a mouse model of myeloma-induced bone disease

PubMed Central

Nyman, Jeffry S.; Merkel, Alyssa R.; Uppuganti, Sasidhar; Nayak, Bijaya; Rowland, Barbara; Makowski, Alexander J.; Oyajobi, Babatunde O.; Sterling, Julie A.

2016-01-01

Multiplemyeloma (MM) patients frequently develop tumor-induced bone destruction, yet no therapy completely eliminates the tumor or fully reverses bone loss. Transforming growth factor-β (TGF-β) activity often contributes to tumor-induced bone disease, and pre-clinical studies have indicated that TGF-β inhibition improves bone volume and reduces tumor growth in bone metastatic breast cancer. We hypothesized that inhibition of TGF-β signaling also reduces tumor growth, increases bone volume, and improves vertebral body strength in MM-bearing mice. We treated myeloma tumor-bearing (immunocompetent KaLwRij and immunocompromised Rag2 −/−) mice with a TGF-β inhibitory (1D11) or control (13C4) antibody, with or without the anti-myeloma drug bortezomib, for 4 weeks after inoculation of murine 5TGM1 MM cells. TGF-β inhibition increased trabecular bone volume, improved trabecular architecture, increased tissue mineral density of the trabeculae as assessed by ex vivo micro-computed tomography, and was associated with significantly greater vertebral body strength in biomechanical compression tests. Serum monoclonal paraprotein titers and spleen weights showed that 1D11 monotherapy did not reduce overall MM tumor burden. Combination therapy with 1D11 and bortezomib increased vertebral body strength, reduced tumor burden, and reduced cortical lesions in the femoral metaphysis, although it did not significantly improve cortical bone strength in three-point bending tests of the mid-shaft femur. Overall, our data provides rationale for evaluating inhibition of TGF-β signaling in combination with existing anti-myeloma agents as a potential therapeutic strategy to improve outcomes in patients with myeloma bone disease. PMID:27423464

Combined treatment with a transforming growth factor beta inhibitor (1D11) and bortezomib improves bone architecture in a mouse model of myeloma-induced bone disease.

PubMed

Nyman, Jeffry S; Merkel, Alyssa R; Uppuganti, Sasidhar; Nayak, Bijaya; Rowland, Barbara; Makowski, Alexander J; Oyajobi, Babatunde O; Sterling, Julie A

2016-10-01

Multiple myeloma (MM) patients frequently develop tumor-induced bone destruction, yet no therapy completely eliminates the tumor or fully reverses bone loss. Transforming growth factor-β (TGF-β) activity often contributes to tumor-induced bone disease, and pre-clinical studies have indicated that TGF-β inhibition improves bone volume and reduces tumor growth in bone metastatic breast cancer. We hypothesized that inhibition of TGF-β signaling also reduces tumor growth, increases bone volume, and improves vertebral body strength in MM-bearing mice. We treated myeloma tumor-bearing (immunocompetent KaLwRij and immunocompromised Rag2-/-) mice with a TGF-β inhibitory (1D11) or control (13C4) antibody, with or without the anti-myeloma drug bortezomib, for 4weeks after inoculation of murine 5TGM1 MM cells. TGF-β inhibition increased trabecular bone volume, improved trabecular architecture, increased tissue mineral density of the trabeculae as assessed by ex vivo micro-computed tomography, and was associated with significantly greater vertebral body strength in biomechanical compression tests. Serum monoclonal paraprotein titers and spleen weights showed that 1D11 monotherapy did not reduce overall MM tumor burden. Combination therapy with 1D11 and bortezomib increased vertebral body strength, reduced tumor burden, and reduced cortical lesions in the femoral metaphysis, although it did not significantly improve cortical bone strength in three-point bending tests of the mid-shaft femur. Overall, our data provides rationale for evaluating inhibition of TGF-β signaling in combination with existing anti-myeloma agents as a potential therapeutic strategy to improve outcomes in patients with myeloma bone disease. Published by Elsevier Inc.

Targeting the LRP5 pathway improves bone properties in a mouse model of Osteogenesis Imperfecta

PubMed Central

Jacobsen, Christina M.; Barber, Lauren A.; Ayturk, Ugur M.; Roberts, Heather J.; Deal, Lauren E.; Schwartz, Marissa A.; Weis, MaryAnn; Eyre, David; Zurakowski, David; Robling, Alexander G.; Warman, Matthew L.

2014-01-01

The cell surface receptor low-density lipoprotein receptor-related protein 5 (LRP5) is a key regulator of bone mass and bone strength. Heterozygous missense mutations in LRP5 cause autosomal dominant high bone mass (HBM) in humans by reducing binding to LRP5 by endogenous inhibitors, such as sclerostin (SOST). Mice heterozygous for a knockin allele (Lrp5p.A214V) that is orthologous to a human HBM-causing mutation have increased bone mass and strength. Osteogenesis Imperfecta (OI) is a skeletal fragility disorder predominantly caused by mutations that affect type I collagen. We tested whether the LRP5 pathway can be used to improve bone properties in animal models of OI. First, we mated Lrp5+/p.A214V mice to Col1a2+/p.G610C mice, which model human type IV OI. We found that Col1a2+/p.G610C;Lrp5+/p.A214V offspring had significantly increased bone mass and strength compared to Col1a2+/p.G610C;Lrp5+/+ littermates. The improved bone properties were not due to altered mRNA expression of type I collagen or its chaperones, nor were they due to changes in mutant type I collagen secretion. Second, we treated Col1a2+/p.G610C mice with a monoclonal antibody that inhibits sclerostin activity (Scl-Ab). We found that antibody treated mice had significantly increased bone mass and strength compared to vehicle treated littermates. These findings indicate increasing bone formation, even without altering bone collagen composition, may benefit patients with OI. PMID:24677211

Effect of Age and Caponization on Blood Parameters and Bone Development of Male Native Chickens in Taiwan

PubMed Central

Lin, Cheng-Yung; Hsu, Jenn-Chung; Wan, Tien-Chun

2012-01-01

An experiment was carried out to determine the effect of age and caponization on the development blood and bone characteristics development in male country chickens in Taiwan. A total of two hundred 8-wk-old LRI native chicken cockerels, Taishi meat No.13 from LRI-COA, were used as experimental animals. Cockerels were surgically caponized at 8 wks of age. Twelve birds in each group were bled and dressed from 8 wks to 35 wks of age at 1 to 5 wk intervals. The results indicated that the plasma testosterone concentration was significantly (p<0.05) lower in capons after 12 wks of age (caponized treatment after 4 wks) than that of the intact males. The relative tibia weight, bone breaking strength, cortical thickness, bone ash, bone calcium, bone phosphorus and bone magnesium contents were significantly (p<0.05) higher in intact males, while capons had higher (p<0.05) plasma ionized calcium, inorganic phosphorus and alkaline phosphatase concentration. The plasma testosterone concentration, relative tibia weight, tibia length, breaking strength, cortical thickness, bone ash, calcium, and phosphorus contents of intact males chickens increased significantly (p<0.05) with the advance of age. In addition, the relative tibia weight of capons peaked at 18 wks of age, and declined at 35 wks of age. The bone ash, calcium and phosphorus content increased most after 14 wks of age in male native chickens in Taiwan. Also, tibia length and cortical thickness peaked at 22 wks of age. However, the peak of bone strength was found at 26 wks of age. These findings support the assertion that androgens can directly influence bone composition fluxes in male chickens. Caponization caused a significant increase in bone loss at 4 wks post treatment, which reflected bone cell damage, and demonstrated reductions in the relative tibia weight, breaking strength, cortical thickness, bone ash, calcium, phosphorus and magnesium contents, and increases in plasma ionized calcium, inorganic phosphorus and alkaline phosphatase concentration. PMID:25049655

Modelling dental implant extraction by pullout and torque procedures.

PubMed

Rittel, D; Dorogoy, A; Shemtov-Yona, K

2017-07-01

Dental implants extraction, achieved either by applying torque or pullout force, is used to estimate the bone-implant interfacial strength. A detailed description of the mechanical and physical aspects of the extraction process in the literature is still missing. This paper presents 3D nonlinear dynamic finite element simulations of a commercial implant extraction process from the mandible bone. Emphasis is put on the typical load-displacement and torque-angle relationships for various types of cortical and trabecular bone strengths. The simulations also study of the influence of the osseointegration level on those relationships. This is done by simulating implant extraction right after insertion when interfacial frictional contact exists between the implant and bone, and long after insertion, assuming that the implant is fully bonded to the bone. The model does not include a separate representation and model of the interfacial layer for which available data is limited. The obtained relationships show that the higher the strength of the trabecular bone the higher the peak extraction force, while for application of torque, it is the cortical bone which might dictate the peak torque value. Information on the relative strength contrast of the cortical and trabecular components, as well as the progressive nature of the damage evolution, can be revealed from the obtained relations. It is shown that full osseointegration might multiply the peak and average load values by a factor 3-12 although the calculated work of extraction varies only by a factor of 1.5. From a quantitative point of view, it is suggested that, as an alternative to reporting peak load or torque values, an average value derived from the extraction work be used to better characterize the bone-implant interfacial strength. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparison of two interpolation methods for empirical mode decomposition based evaluation of radiographic femur bone images.

PubMed

Udhayakumar, Ganesan; Sujatha, Chinnaswamy Manoharan; Ramakrishnan, Swaminathan

2013-01-01

Analysis of bone strength in radiographic images is an important component of estimation of bone quality in diseases such as osteoporosis. Conventional radiographic femur bone images are used to analyze its architecture using bi-dimensional empirical mode decomposition method. Surface interpolation of local maxima and minima points of an image is a crucial part of bi-dimensional empirical mode decomposition method and the choice of appropriate interpolation depends on specific structure of the problem. In this work, two interpolation methods of bi-dimensional empirical mode decomposition are analyzed to characterize the trabecular femur bone architecture of radiographic images. The trabecular bone regions of normal and osteoporotic femur bone images (N = 40) recorded under standard condition are used for this study. The compressive and tensile strength regions of the images are delineated using pre-processing procedures. The delineated images are decomposed into their corresponding intrinsic mode functions using interpolation methods such as Radial basis function multiquadratic and hierarchical b-spline techniques. Results show that bi-dimensional empirical mode decomposition analyses using both interpolations are able to represent architectural variations of femur bone radiographic images. As the strength of the bone depends on architectural variation in addition to bone mass, this study seems to be clinically useful.

In vitro evaluation of electrospun chitosan mats crosslinked with genipin as guided tissue regeneration barrier membranes

NASA Astrophysics Data System (ADS)

Norowski, Peter Andrew, Jr.

Guided tissue regeneration (GTR) is a surgical technique commonly used to exclude bacteria and soft tissues from bone graft sites in oral/maxillofacial bone graft sites by using a barrier membrane to maintain the graft contour and space. Current clinical barrier membrane materials based on expanded polytetrafluoroethylene (ePTFE) and bovine type 1 collagen are non-ideal and experience a number of disadvantages including membrane exposure, bacterial colonization/biofilm formation and premature degradation, all of which result in increased surgical intervention and poor bone regeneration. These materials do not actively participate in tissue regeneration, however bioactive materials, such as chitosan, may provide advantages such as the ability to stimulate wound healing and de novo bone formation. Our hypothesis is that electrospun chitosan GTR membranes will support cell attachment and growth but prevent cell infiltration/penetration of membrane, demonstrate in vitro degradation predictive of 4--6 month in vivo functionality, and will deliver antibiotics locally to prevent/inhibit periopathogenic complications. To test this hypothesis a series of chitosan membranes were electrospun, in the presence or absence of genipin, a natural crosslinking agent, at concentrations of 5 and 10 mM. These membranes were characterized by scanning electron microscopy, tensile testing, suture pullout testing, Fourier transform infrared spectroscopy, X-ray diffraction, and gel permeation chromatography, and in vitro biodegradation for diameter/morphology of fibers, membrane strengths, degree of crosslinking, crystallinity, molecular weight, and degradation kinetics, respectively. Cytocompability of membranes was evaluated in osteoblastic, fibroblastic and monocyte cultures. The activity of minocycline loaded and released from the membranes was determined in zone of inhibition tests using P. gingivalis microbe. The results demonstrated that genipin crosslinking extended the in vitro degradation timeframe, extended the release of minocycline, and increased the tensile strength of the resultant membranes while cytocompatibility, swelling, and tear strength were unaffected. In conclusion, electrospun chitosan membranes crosslinked with genipin are a suitable material for guided tissue regeneration and may help reduce bacterial infection and bacteria-induced host inflammatory response.

Estimating the strength of bone using linear response

NASA Astrophysics Data System (ADS)

Gunaratne, Gemunu H.

2002-12-01

Accurate diagnostic tools are required for effective management of osteoporosis; one method to identify additional diagnostics is to search for observable consequences of bone loss. An analysis of a model system is used to show that weakening of a bone is accompanied by a reduction of the fraction of the bone that participates in load transmission. On the basis of this observation, it is argued that the ratio Γ of linear responses of a network to dc and high-frequency ac driving can be used as a surrogate for their strength. Protocols needed to obtain Γ for bone samples are discussed.

Load to Failure and Stiffness

PubMed Central

Esquivel, Amanda O.; Duncan, Douglas D.; Dobrasevic, Nikola; Marsh, Stephanie M.; Lemos, Stephen E.

2015-01-01

Background: Rotator cuff tendinopathy is a frequent cause of shoulder pain that can lead to decreased strength and range of motion. Failures after using the single-row technique of rotator cuff repair have led to the development of the double-row technique, which is said to allow for more anatomical restoration of the footprint. Purpose: To compare 5 different types of suture patterns while maintaining equality in number of anchors. The hypothesis was that the Mason-Allen–crossed cruciform transosseous-equivalent technique is superior to other suture configurations while maintaining equality in suture limbs and anchors. Study Design: Controlled laboratory study. Methods: A total of 25 fresh-frozen cadaveric shoulders were randomized into 5 suture configuration groups: single-row repair with simple stitch technique; single-row repair with modified Mason-Allen technique; double-row Mason-Allen technique; double-row cross-bridge technique; and double-row suture bridge technique. Load and displacement were recorded at 100 Hz until failure. Stiffness and bone mineral density were also measured. Results: There was no significant difference in peak load at failure, stiffness, maximum displacement at failure, or mean bone mineral density among the 5 suture configuration groups (P < .05). Conclusion: According to study results, when choosing a repair technique, other factors such as number of sutures in the repair should be considered to judge the strength of the repair. Clinical Relevance: Previous in vitro studies have shown the double-row rotator cuff repair to be superior to the single-row repair; however, clinical research does not necessarily support this. This study found no difference when comparing 5 different repair methods, supporting research that suggests the number of sutures and not the pattern can affect biomechanical properties. PMID:26665053

Protocol for a randomized controlled trial to compare bone-loading exercises with risedronate for preventing bone loss in osteopenic postmenopausal women.

PubMed

Bilek, Laura D; Waltman, Nancy L; Lappe, Joan M; Kupzyk, Kevin A; Mack, Lynn R; Cullen, Diane M; Berg, Kris; Langel, Meghan; Meisinger, Melissa; Portelli-Trinidad, Ashlee; Lang, Molly

2016-08-30

In the United States, over 34 million American post-menopausal women have low bone mass (osteopenia) which increases their risk of osteoporosis and fractures. Calcium, vitamin D and exercise are recommended for prevention of osteoporosis, and bisphosphonates (BPs) are prescribed in women with osteoporosis. BPs may also be prescribed for women with low bone mass, but are more controversial due to the potential for adverse effects with long-term use. A bone loading exercise program (high-impact weight bearing and resistance training) promotes bone strength by preserving bone mineral density (BMD), improving bone structure, and by promoting bone formation at sites of mechanical stress. The sample for this study will be 309 women with low bone mass who are within 5 years post-menopause. Subjects are stratified by exercise history (≥2 high intensity exercise sessions per week; < 2 sessions per week) and randomized to a control or one of two treatment groups: 1) calcium + vitamin D (CaD) alone (Control); 2) a BP plus CaD (Risedronate); or 3) a bone loading exercise program plus CaD (Exercise). After 12 months of treatment, changes in bone structure, BMD, and bone turnover will be compared in the 3 groups. Primary outcomes for the study are bone structure measures (Bone Strength Index [BSI] at the tibia and Hip Structural Analysis [HSA] scores). Secondary outcomes are BMD at the hip and spine and serum biomarkers of bone formation (alkaline phosphase, AlkphaseB) and resorption (Serum N-terminal telopeptide, NTx). Our central hypothesis is that improvements in bone strength will be greater in subjects randomized to the Exercise group compared to subjects in either Control or Risedronate groups. Our research aims to decrease the risk of osteoporotic fractures by improving bone strength in women with low bone mass (pre-osteoporotic) during their first 5 years' post-menopause, a time of rapid and significant bone loss. Results of this study could be used in developing a clinical management pathway for women with low bone mass at their peak period of bone loss that would involve lifestyle modifications such as exercises prior to medications such as BPs. Clinicaltrials.gov NCT02186600 . Initial registration: 7/7/2014.

Factors affecting the pullout strength of cancellous bone screws.

PubMed

Chapman, J R; Harrington, R M; Lee, K M; Anderson, P A; Tencer, A F; Kowalski, D

1996-08-01

Screws placed into cancellous bone in orthopedic surgical applications, such as fixation of fractures of the femoral neck or the lumbar spine, can be subjected to high loads. Screw pullout is a possibility, especially if low density osteoporotic bone is encountered. The overall goal of this study was to determine how screw thread geometry, tapping, and cannulation affect the holding power of screws in cancellous bone and determine whether current designs achieve maximum purchase strength. Twelve types of commercially available cannulated and noncannulated cancellous bone screws were tested for pullout strength in rigid unicellular polyurethane foams of apparent densities and shear strengths within the range reported for human cancellous bone. The experimentally derived pullout strength was compared to a predicted shear failure force of the internal threads formed in the polyurethane foam. Screws embedded in porous materials pullout by shearing the internal threads in the porous material. Experimental pullout force was highly correlated to the predicted shear failure force (slope = 1.05, R2 = 0.947) demonstrating that it is controlled by the major diameter of the screw, the length of engagement of the thread, the shear strength of the material into which the screw is embedded, and a thread shape factor (TSF) which accounts for screw thread depth and pitch. The average TSF for cannulated screws was 17 percent lower than that of noncannulated cancellous screws, and the pullout force was correspondingly less. Increasing the TSF, a result of decreasing thread pitch or increasing thread depth, increases screw purchase strength in porous materials. Tapping was found to reduce pullout force by an average of 8 percent compared with nontapped holes (p = 0.0001). Tapping in porous materials decreases screw pullout strength because the removal of material by the tap enlarges hole volume by an average of 27 percent, in effect decreasing the depth and shear area of the internal threads in the porous material.

Association of Insulin Resistance with Bone Strength and Bone Turnover in Menopausal Chinese-Singaporean Women without Diabetes.

PubMed

Kalimeri, Maria; Leek, Francesca; Wang, Nan Xin; Koh, Huann Rong; Roy, Nicole C; Cameron-Smith, David; Kruger, Marlena C; Henry, Christiani Jeyakumar; Totman, John J

2018-04-30

Insulin resistance (IR) is accompanied by increased areal or volumetric bone mineral density (aBMD or vBMD), but also higher fracture risk. Meanwhile, imbalances in bone health biomarkers affect insulin production. This study investigates the effect of IR on proximal femur and lumbar spine BMD, femoral neck bending, compressive and impact strength indices (Composite Strength Indices) and circulating levels of parathyroid hormone (PTH), C-telopeptide of Type I collagen (CTx-1) and 25(OH) Vitamin D₃, in a cohort of 97 healthy, non-obese, menopausal Chinese-Singaporean women. Lumbar spine aBMD was inversely associated with IR and dependent on lean body mass (LBM) and age. No such associations were found for vBMD of the third lumbar vertebra, aBMD and vBMD of the proximal femur, or circulating levels of PTH, CTx-1 and 25(OH) Vitamin D₃. Composite Strength Indices were inversely associated with IR and independent of LBM, but after adjusting for fat mass and age, this association remained valid only for the impact strength index. Composite Strength Indices were significantly lower in participants with a high degree of IR. Our findings on IR and Composite Strength Indices relationships were in agreement with previous studies on different cohorts, but those on IR and BMD associations were not.

Dietary 2-oxoglutarate prevents bone loss caused by neonatal treatment with maximal dexamethasone dose

PubMed Central

Tomaszewska, Ewa; Muszyński, Siemowit; Blicharski, Tomasz; Pierzynowski, Stefan G

2017-01-01

Synthetic glucocorticoids (GCs) are widely used in the variety of dosages for treatment of premature infants with chronic lung disease, respiratory distress syndrome, allergies, asthma, and other inflammatory and autoimmune conditions. Yet, adverse effects such as glucocorticoid-induced osteoporosis and growth retardation are recognized. Conversely, 2-oxoglutarate (2-Ox), a precursor of glutamine, glutamate, and collagen amino acids, exerts protective effects on bone development. Our aim was to elucidate the effect of dietary administered 2-Ox on bone loss caused by neonatal treatment with clinically relevant maximal therapeutic dexamethasone (Dex) dose. Long bones of neonatal female piglets receiving Dex, Dex+2-Ox, or untreated were examined through measurements of mechanical properties, density, mineralization, geometry, histomorphometry, and histology. Selected hormones, bone turnover, and growth markers were also analyzed. Neonatal administration of clinically relevant maximal dose of Dex alone led to over 30% decrease in bone mass and the ultimate strength (P < 0.001 for all). The length (13 and 7% for femur and humerus, respectively) and other geometrical parameters (13–45%) decreased compared to the control (P < 0.001 for all). Dex impaired bone growth and caused hormonal imbalance. Dietary 2-Ox prevented Dex influence and vast majority of assessed bone parameters were restored almost to the control level. Piglets receiving 2-Ox had heavier, denser, and stronger bones; higher levels of growth hormone and osteocalcin concentration; and preserved microarchitecture of trabecular bone compared to the Dex group. 2-Ox administered postnatally had a potential to maintain bone structure of animals simultaneously treated with maximal therapeutic doses of Dex, which, in our opinion, may open up a new opportunity in developing combined treatment for children treated with GCs. Impact statement The present study has showed, for the first time, that dietary 2-oxoglutarate (2-Ox) administered postnatally has a potential to improve/maintain bone structure of animals simultaneously treated with maximal therapeutic doses of dexamethasone (Dex). It may open the new direction in searching and developing combined treatment for children treated with glucocorticoids (GCs) since growing group of children is exposed to synthetic GCs and adverse effects such as glucocorticoid-induced osteoporosis and growth retardation are recognized. Currently proposed combined therapies have numerous side effects. Thus, this study proposed a new direction in combined therapies utilizing dietary supplementation with glutamine derivative. Impairment caused by Dex in presented long bones animal model was prevented by dietary supplementation with 2-Ox and vast majority of assessed bone parameters were restored almost to the control level. These results support previous thesis on the regulatory mechanism of nutrient utilization regulated by glutamine derivatives and enrich the nutritional science. PMID:28178857

Influences of physical fitness on bone mass in women with fibromyalgia.

PubMed

Gómez-Cabello, Alba; Vicente-Rodríguez, Germán; Navarro-Vera, Isabel; Martinez-Redondo, Diana; Díez-Sánchez, Carmen; Casajús, José Antonio

2015-04-01

The aim of this study was to provide information about the relationship of bone mineral content (BMC) and density (BMD) with some physical-fitness-related variables in a sample of women with fibromyalgia (FM) and age-matched women without FM. Twenty-eight women clinically diagnosed with FM (age 51.1 ± 8.4 yr, M ± SD) and 22 age-matched controls participated in the study. Whole-body BMC and BMD, lean mass, handgrip strength, quadriceps strength, and cardiovascular fitness were measured in all participants. The association between physical-fitness variables and bone-related variables was tested by linear regression controlling for body weight as a possible confounder. There were no differences in BMC or BMD between groups. Women with FM had lower values of handgrip strength, quadriceps strength, and VO2peak than the control group. Handgrip strength and aerobic capacity were associated with BMC and BMD and quadriceps strength was associated with BMD in women with FM; however, only VO2peak was associated with BMC in the group of women without FM. Bone mass of women with FM may be more susceptible to changes in physical fitness than that of the women without fibromyalgia.

Preparation and characterization of calcium phosphate ceramics and composites as bone substitutes

NASA Astrophysics Data System (ADS)

Zhang, Xing

Marine CaCO3 skeletons have tailored architectures created by nature, which give them structural support and other functions. For example, seashells have dense lamellar structures, while coral, cuttlebone and sea urchin spines have interconnected porous structures. In our experiments, seashells, coral and cuttlebone were hydrothermally converted to hydroxyapatite (HAP), and sea urchin spines were converted to Mg-substituted tricalcium phosphate (beta-TCMP), while maintaining their original structures. Partially converted shell samples have mechanical strength, which is close to that of compact human bone. After implantation of converted shell and spine samples in rat femoral defects for 6 weeks, there was newly formed bone growth up to and around the implants. Some new bone was found to migrate through the pores of converted spine samples and grow inward. These results show good bioactivity and osteoconductivity of the implants, indicating the converted shell and spine samples can be used as bone defect fillers. Calcium phosphate powders were prepared through different synthesis methods. Micro-size HAP rods were synthesized by hydrothermal method through a nucleation-growth mechanism. On the other hand, HAP particles, which have good crystallinity, were prepared by wet precipitation with further hydrothermal treatment. beta-TCP or beta-TCMP powders were prepared by a two-step process: wet precipitation of apatitic tricalcium phosphate ('precursor') and calcination of the precursor at 800°C for 3 hours. beta-TCMP or beta-TCP powders were also prepared by solid-state reactions from CaHPO4 and CaCO 3 with/without MgO. Biphasic calcium phosphate, which is mixture of HAP and beta-TCP, can be prepared though mechanical mixing of HAP and beta-TCP powders synthesized as above. Dense beta-TCP and beta-TCMP ceramics can be produced by pressing green bodies at 100MPa and further sintering above 1100°C for 2 hours. beta-TCMP ceramics ˜99.4% relative dense were prepared by this method. Dense beta-TCP ceramics have average strength up to 540MPa. Macroporous beta-TCMP ceramics were produced with sucrose as the porogen following a two-step pressing method. Porous beta-TCMP ceramics were also prepared by replication of polyurethane sponge. beta-TCMP ceramics with porous structures in the center surrounded by dense structures were created. The outside dense structures give the scaffold mechanical strength, while the central porous structures enable cells migration and vascular infiltration, and finally in-growth of new bone into the scaffold.

A method for vibrational assessment of cortical bone

NASA Astrophysics Data System (ADS)

Song, Yan; Gunaratne, Gemunu H.

2006-09-01

Large bones from many anatomical locations of the human skeleton consist of an outer shaft (cortex) surrounding a highly porous internal region (trabecular bone) whose structure is reminiscent of a disordered cubic network. Age related degradation of cortical and trabecular bone takes different forms. Trabecular bone weakens primarily by loss of connectivity of the porous network, and recent studies have shown that vibrational response can be used to obtain reliable estimates for loss of its strength. In contrast, cortical bone degrades via the accumulation of long fractures and changes in the level of mineralization of the bone tissue. In this paper, we model cortical bone by an initially solid specimen with uniform density to which long fractures are introduced; we find that, as in the case of trabecular bone, vibrational assessment provides more reliable estimates of residual strength in cortical bone than is possible using measurements of density or porosity.

Volumetric bone mineral density (vBMD), bone structure, and structural geometry among rural South Indian, US Caucasian, and Afro-Caribbean older men.

PubMed

Jammy, Guru Rajesh; Boudreau, Robert M; Singh, Tushar; Sharma, Pawan Kumar; Ensrud, Kristine; Zmuda, Joseph M; Reddy, P S; Newman, Anne B; Cauley, Jane A

2018-05-22

Peripheral quantitative computed tomography (pQCT) provides biomechanical estimates of bone strength. Rural South Indian men have reduced biomechanical indices of bone strength compared to US Caucasian and Afro-Caribbean men. This suggests an underlying higher risk of osteoporotic fractures and greater future fracture burden among the rural South Indian men. Geographical and racial comparisons of bone mineral density (BMD) have largely focused on DXA measures of areal BMD. In contrast, peripheral quantitative computed tomography (pQCT) measures volumetric BMD (vBMD), bone structural geometry and provides estimates of biomechanical strength. To further understand potential geographical and racial differences in skeletal health, we compared pQCT measures among US Caucasian, Afro-Caribbean, and rural South Indian men. We studied men aged ≥ 60 years enrolled in the Mobility and Independent Living among Elders Study (MILES) in rural south India (N = 245), Osteoporotic Fractures in Men Study (MrOS) in the US (N = 1148), and the Tobago Bone Health Study (N = 828). The BMI (kg/m 2 ) of rural South Indian men (21.6) was significantly lower compared to the US Caucasians (28) and Afro-Caribbean men (26.9). Adjusting for age, height, body weight, and grip strength; rural South Indian men compared to US Caucasians had significantly lower trabecular vBMD [- 1.3 to - 1.5 standard deviation (SD)], cortical thickness [- 0.8 to - 1.2 SD]; significantly higher endosteal circumference [0.5 to 0.8 SD]; but similar cortical vBMD. Afro-Caribbean men compared to US Caucasians had similar trabecular vBMD but significantly higher cortical vBMD [0.9 to 1.2 SD], SSIp [0.2 to 1.4 SD], and tibial endosteal circumference [1 SD], CONCLUSIONS: In comparison to US Caucasians, rural South Indian men have reduced bone strength (lower trabecular vBMD) and Afro-Caribbean men have greater bone strength (higher cortical vBMD). These results suggest an underlying higher risk of osteoporotic fractures and greater future fracture burden among rural South Indian men.

Bone density and the lightweight skeletons of birds.

PubMed

Dumont, Elizabeth R

2010-07-22

The skeletons of birds are universally described as lightweight as a result of selection for minimizing the energy required for flight. From a functional perspective, the weight (mass) of an animal relative to its lift-generating surfaces is a key determinant of the metabolic cost of flight. The evolution of birds has been characterized by many weight-saving adaptations that are reflected in bone shape, many of which strengthen and stiffen the skeleton. Although largely unstudied in birds, the material properties of bone tissue can also contribute to bone strength and stiffness. In this study, I calculated the density of the cranium, humerus and femur in passerine birds, rodents and bats by measuring bone mass and volume using helium displacement. I found that, on average, these bones are densest in birds, followed closely by bats. As bone density increases, so do bone stiffness and strength. Both of these optimization criteria are used in the design of strong and stiff, but lightweight, manmade airframes. By analogy, increased bone density in birds and bats may reflect adaptations for maximizing bone strength and stiffness while minimizing bone mass and volume. These data suggest that both bone shape and the material properties of bone tissue have played important roles in the evolution of flight. They also reconcile the conundrum of how bird skeletons can appear to be thin and delicate, yet contribute just as much to total body mass as do the skeletons of terrestrial mammals.

Proximal half angle of the screw thread is a critical design variable affecting the pull-out strength of cancellous bone screws.

PubMed

Wang, Yingxu; Mori, Ryuji; Ozoe, Nobuaki; Nakai, Takahisa; Uchio, Yuji

2009-11-01

Screws with strong pull-out strength have been sought for the treatment of cancellous bone. We hypothesized that an obliquely angled screw thread has advantages over conventional vertical thread with a minimal proximal half angle. Metal and bone screws were made of stainless steel and porcine cortical bone. Their proximal half angle was set at 0 degrees , 30 degrees , or 60 degrees . The screws were inserted into porcine cancellous bone. At 0 degrees , the thread faced the recipient bone vertically. Pullout tests at a rate of 30 mm/min (n=40, each screw type) and microcomputed tomography (n=6) were conducted. The pull-out strength of the screws was maximal at 30 degrees ; 348.8 (SD, 44.1)N with metal and 326.6 (39.4)N with bone. It was intermediate at 0 degrees ; 301.9 (35.9)N with metal and 278.2 (30.6)N with bone. It was minimal at 60 degrees; 126.5 (39.0)N with metal and 174.8 (29.7)N with bone. Cancellous bone was damaged between the threads at 30 degrees , while intact cancellous bone was preserved between the threads at 0 degrees. A proximal half angle of around 30 degrees is appropriate because the pullout force is applied to the recipient bone evenly. Commercial cancellous screws can be improved by changing the thread shape to minimize the damage to recipient bone.

Preparation and Characterization of Biomimetic Hydroxyapatite-Resorbable Polymer Composites for Hard Tissue Repair

NASA Astrophysics Data System (ADS)

Hiebner, Kristopher Robert

Autografts are the orthopedic "gold standard" for repairing bone voids. Autografts are osteoconductive and do not elicit an immune response, but they are in short supply and require a second surgery to harvest the bone graft. Allografts are currently the most common materials used for the repair of segmental defects in hard tissue. Unlike autografts, allografts can cause an undesirable immune response and the possibility of disease transmission is a major concern. As an alternative to the above approaches, recent research efforts have focused on the use of composite materials made from hydroxyapatite (HA) and bioresorbable polymers, such as poly-L-lactide (PLLA). Recent results have shown that the surface hydroxides on HA can initiate the ring opening polymerization (ROP) of L-lactide and other lactones creating a composite with superior interfacial strength. This thesis demonstrates that the surface of porous biologically derived HA substrates, such as coralline HA and trabecular bone, can be used to initiate the ROP of L-lactide and other lactones from the vapor phase. This process increases the strength of the porous scaffold through the deposition of a thin, uniform polymer coating, while maintaining the porous structure. The kinetics of the chemical vapor deposition polymerization (CVDP) are described using a quartz crystal microbalance (QCM). The reaction temperature and monomer vapor pressure are found to affect the rate of the polymerization. Also described in this thesis is the preparation of a porous polymer scaffold that mimics the structure of demineralized bone matrix (DBM). This demineralized bone matrix simulant (DBMS) is created using anorganic bovine bone as a template to initiate the polymerization of various lactones, followed by the removal of the HA scaffold. This material retained its shape and exhibits mechanical properties superior to DBM. Finally it is shown that HA can be used to initiate the ROP of a-caprolactam and the biocompatibility of various HA/bioresorbable polymer composites are described through the use of cell cultures run in collaboration with a research group specializing in immunology.

Bone bonding strength of diamond-structured porous titanium-alloy implants manufactured using the electron beam-melting technique.

PubMed

Hara, Daisuke; Nakashima, Yasuharu; Sato, Taishi; Hirata, Masanobu; Kanazawa, Masayuki; Kohno, Yusuke; Yoshimoto, Kensei; Yoshihara, Yusuke; Nakamura, Akihiro; Nakao, Yumiko; Iwamoto, Yukihide

2016-02-01

The present study examined the bone bonding strength of diamond-structured porous titanium-alloy (Porous-Ti-alloy) manufactured using the electron beam-melting technique in comparison with fiber mesh-coated or rough-surfaced implants. Cylindrical implants with four different pore sizes (500, 640, 800, and 1000μm) of Porous-Ti-alloy, titanium fiber mesh (FM), and surfaces roughened by titanium arc spray (Ti-spray) were implanted into the distal femur of rabbits. Bone bonding strength and histological bone ingrowth were evaluated at 4 and 12weeks after implantation. The bone bonding strength of Porous-Ti-alloy implants (640μm pore size) increased over time from 541.4N at 4weeks to 704.6N at 12weeks and was comparable to that of FM and Ti-spray implants at both weeks. No breakage of the porous structure after mechanical testing was found with Porous-Ti-alloy implants. Histological bone ingrowth that increased with implantation time occurred along the inner structure of Porous-Ti-alloy implants. There was no difference in bone ingrowth in Porous-Ti-alloy implants with pore sizes among 500, 640, and 800μm; however, less bone ingrowth was observed with the 1000μm pore size. These results indicated Porous-Ti-alloy implants with pore size under 800μm provided biologically active and mechanically stable surface for implant fixation to bone, and had potential advantages for weight bearing orthopedic implants such as acetabular cups. Copyright © 2015 Elsevier B.V. All rights reserved.

The soy isoflavones for reducing bone loss study: 3-yr effects on pQCT bone mineral density and strength measures in postmenopausal women.

PubMed

Shedd-Wise, Kristine M; Alekel, D Lee; Hofmann, Heike; Hanson, Kathy B; Schiferl, Dan J; Hanson, Laura N; Van Loan, Marta D

2011-01-01

Soy isoflavones exert inconsistent bone density-preserving effects, but the bone strength-preserving effects in humans are unknown. Our double-blind randomized controlled trial examined 2 soy isoflavone doses (80 or 120mg/d) vs placebo tablets on volumetric bone mineral density (vBMD) and strength (by means of peripheral quantitative computed tomography) in healthy postmenopausal women (46-63yr). We measured 3-yr changes in cortical BMD (CtBMD), cortical thickness (CtThk), periosteal circumference (PC), endosteal circumference (EC), and strength-strain index (SSI) at 1/3 midshaft femur (N=171), and trabecular BMD (TbBMD), PC, and SSI at 4% distal tibia (N=162). We found no treatment effect on femur CtThk, PC, or EC, or tibia TbBMD or PC. The strongest predictors (negative) of tibia TbBMD and SSI and femur CtBMD were timepoint and bone resorption; whole-body fat mass was protective of SSI. As time since last menstrual period (TLMP) increased (p=0.012), 120-mg/d dose was protective of CtBMD. The strongest predictors of femur SSI were timepoint, bone resorption, and TLMP (protective). Isoflavone tablets were negative predictors of SSI, but 80-mg/d dose became protective as bone turnover increased (p=0.011). Soy isoflavone treatment for 3yr was modestly beneficial for midshaft femur vBMD as TLMP increased and for midshaft femur SSI as bone turnover increased. Copyright © 2011 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.

Prediction of trabecular bone qualitative properties using scanning quantitative ultrasound

NASA Astrophysics Data System (ADS)

Qin, Yi-Xian; Lin, Wei; Mittra, Erik; Xia, Yi; Cheng, Jiqi; Judex, Stefan; Rubin, Clint; Müller, Ralph

2013-11-01

Microgravity induced bone loss represents a critical health problem in astronauts, particularly occurred in weight-supporting skeleton, which leads to osteopenia and increase of fracture risk. Lack of suitable evaluation modality makes it difficult for monitoring skeletal status in long term space mission and increases potential risk of complication. Such disuse osteopenia and osteoporosis compromise trabecular bone density, and architectural and mechanical properties. While X-ray based imaging would not be practical in space, quantitative ultrasound may provide advantages to characterize bone density and strength through wave propagation in complex trabecular structure. This study used a scanning confocal acoustic diagnostic and navigation system (SCAN) to evaluate trabecular bone quality in 60 cubic trabecular samples harvested from adult sheep. Ultrasound image based SCAN measurements in structural and strength properties were validated by μCT and compressive mechanical testing. This result indicated a moderately strong negative correlations observed between broadband ultrasonic attenuation (BUA) and μCT-determined bone volume fraction (BV/TV, R2=0.53). Strong correlations were observed between ultrasound velocity (UV) and bone's mechanical strength and structural parameters, i.e., bulk Young's modulus (R2=0.67) and BV/TV (R2=0.85). The predictions for bone density and mechanical strength were significantly improved by using a linear combination of both BUA and UV, yielding R2=0.92 for BV/TV and R2=0.71 for bulk Young's modulus. These results imply that quantitative ultrasound can characterize trabecular structural and mechanical properties through measurements of particular ultrasound parameters, and potentially provide an excellent estimation for bone's structural integrity.

Bone mineral density, serum albumin and serum magnesium.

PubMed

Saito, Noboru; Tabata, Naoto; Saito, Saburou; Andou, Yoshihisa; Onaga, Yukiko; Iwamitsu, Akihiro; Sakamoto, Morihide; Hori, Tuyoshi; Sayama, Harumi; Kawakita, Toshiko

2004-12-01

This study explores clinical and laboratory abnormalities that contribute to the prevalence of bone fractures in frail and control elderly patients, to ascertain factors that relate to bone strength and fragility. Patients were selected as free from renal failure and not taking supplements or medications that affect their magnesium status, and categorized according to their underlying diseases, sex and age, and evaluated by tests of bone strength. Findings, differentiating elderly patients on the basis of their magnesium, calcium, serum albumin, body mass, bone mineral density and their fracture occurrence were tabulated. Evidence is presented of low magnesium and albumin serum levels, especially in women with low bone density, as well as of low calcium and trace minerals.

Calcaneal bone mineral density and mechanical strength of the metatarsals.

PubMed

Lidtke, R H; Patel, D; Muehleman, C

2000-10-01

The primary aim of this study was to determine the predictive value of the bone mineral density of the calcaneus for fracture of the metatarsals. The authors report a strong positive correlation between the bone mineral density of the calcaneus and the four-point bending strength of each of the five metatarsals (r2 = 0.76, 0.64, 0.70, 0.68, and 0.78 for metatarsals 1 through 5, respectively). In addition, the relative strengths of the metatarsals and the correlation with their in vivo loads during gait as previously reported in the literature are discussed.

Influence of cement compressive strength and porosity on augmentation performance in a model of orthopedic screw pull-out.

PubMed

Pujari-Palmer, Michael; Robo, Celine; Persson, Cecilia; Procter, Philip; Engqvist, Håkan

2018-01-01

Disease and injuries that affect the skeletal system may require surgical intervention and internal fixation, i.e. orthopedic plate and screw insertion, to stabilize the injury and facilitate tissue repair. If the surrounding bone quality is poor the screws may migrate, or the bone may fail, resulting in fixation failure. While numerous studies have shown that cement augmentation of the interface between bone and implant can increase screw pull-out force, the physical properties of cement that influence pull-out force have not been investigated. The present study sought to determine how the physical properties of high strength calcium phosphate cements (hsCPCs, specifically dicalcium phosphate) affected the corresponding orthopedic screw pull-out force in urethane foam models of "healthy" and "osteoporotic" synthetic bone (Sawbones). In the simplest model, where only the bond strength between screw thread and cement (without Sawbone) was tested, the correlation between pull-out force and cement compressive strength (R 2 = 0.79) was weaker than correlation with total cement porosity (R 2 = 0.89). In open pore Sawbone that mimics "healthy" cancellous bone density the stronger cements produced higher pull-out force (50-60% increase). High strength, low porosity cements also produced higher pull-out forces (50-190% increase) in "healthy" Sawbones with cortical fixation if the failure strength of the cortical material was similar to, or greater than (a metal shell), actual cortical bone. This result is of particular clinical relevance where fixation with a metal plate implant is indicated, as the nearby metal can simulate a thicker cortical shell, thereby increasing the pull-out force of screws augmented with stronger cements. The improvement in pull-out force was apparent even at low augmentation volumes of 0.5mL (50% increase), which suggest that in clinical situations where augmentation volume is limited the stronger, lower porosity calcium phosphate cement (CPC) may still produce a significant improvement in screw pull-out force. When the correlation strength of all the tested models were compared both cement porosity and compressive strength accurately predicted pull-out force (R 2 =1.00, R 2 =0.808), though prediction accuracy depended upon the strength of the material surrounding the Sawbone. The correlations strength was low for bone with no, or weak, cortical fixation (R 2 =0.56, 0.36). Higher strength and lower porosity CPCs also produced greater pull-out force (1-1.5kN) than commercial CPC (0.2-0.5kN), but lower pull-out force than PMMA (2-3kN). The results of this study suggest that the likelihood of screw fixation failure may be reduced by selecting calcium phosphate cements with lower porosity and higher compressive strength, in patients with healthy bone mineral density and/or sufficient cortical thickness. This is of particular clinical relevance when fixation with metal plates is indicated, or where the augmentation volume is limited. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bone geometry in young male and female football players: a peripheral quantitative computed tomography (pQCT) study.

PubMed

Lozano-Berges, Gabriel; Matute-Llorente, Ángel; Gómez-Bruton, Alejandro; González-Agüero, Alex; Vicente-Rodríguez, Germán; Casajús, José A

2018-05-08

The present study shows that football practice during growth may improve bone geometry in male and female football players. However, only females had better bone strength in comparison with controls. The aim of this study was to compare bone geometry in adolescent football players and controls. A total of 107 football players (71 males/36 females; mean age 12.7 ± 0.6/12.7 ± 0.6 years) and 42 controls (20 males/22 females; mean age 13.1 ± 1.4/12.7 ± 1.3 years) participated in this study. Total and trabecular volumetric bone mineral content (Tt.BMC/Tb.BMC), cross-sectional area (Tt.Ar/Tb.Ar), and bone strength index (BSI) were measured at 4% site of the non-dominant tibia by peripheral quantitative computed tomography (pQCT). Moreover, Tt.BMC, cortical BMC (Ct.BMC), Tt.Ar, cortical Ar (Ct.Ar), cortical thickness (Ct.Th), periosteal circumference (PC), endosteal circumference (EC), fracture load in X-axis, and polar strength strain index (SSIp) were measured at 38% site of the tibia. Multivariate analyses of covariance were used to compare bone pQCT variables between football players and controls using the tibia length and maturity offset as covariates. Female football players demonstrated 13.8-16.4% higher BSI, Ct.Th, fracture load in X-axis, and SSIp than controls (p < .0036). Males showed no significant differences in bone strength when compared to controls (p > .0036). In relation to bone mineral content and area, male football players showed 8.8% higher Tt.Ar and Tb.Ar at the 4% site of the tibia when compared to controls; whereas 13.8-15.8% higher Tt.BMC, Ct.BMC, and Ct.Ar at the 38% site of the tibia were found in female football players than controls (p < .0036). In this study, female adolescent football players presented better bone geometry and strength values than controls. In contrast, only bone geometry was higher in male football players than controls.

Direct Lentiviral-Cyclooxygenase 2 Application to the Tendon-Bone Interface Promotes Osteointegration and Enhances Return of the Pull-Out Tensile Strength of the Tendon Graft in a Rat Model of Biceps Tenodesis

PubMed Central

Wergedal, Jon E.; Stiffel, Virginia; Lau, Kin-Hing William

2014-01-01

This study sought to determine if direct application of the lentiviral (LV)-cyclooxygenase 2 (COX2) vector to the tendon-bone interface would promote osteointegration of the tendon graft in a rat model of biceps tenodesis. The LV-COX2 gene transfer strategy was chosen for investigation because a similar COX2 gene transfer strategy promoted bony bridging of the fracture gap during bone repair, which involves similar histologic transitions that occur in osteointegration. Briefly, a 1.14-mm diameter tunnel was drilled in the mid-groove of the humerus of adult Fischer 344 rats. The LV-COX2 or βgal control vector was applied directly into the bone tunnel and onto the end of the tendon graft, which was then pulled into the bone tunnel. A poly-L-lactide pin was press-fitted into the tunnel as interference fixation. Animals were sacrificed at 3, 5, or 8 weeks for histology analysis of osteointegration. The LV-COX2 gene transfer strategy enhanced neo-chondrogenesis at the tendon-bone interface but with only marginal effect on de novo bone formation. The tendon-bone interface of the LV-COX2-treated tenodesis showed the well-defined tendon-to-fibrocartilage-to-bone histologic transitions that are indicative of osteointegration of the tendon graft. The LV-COX2 in vivo gene transfer strategy also significantly enhanced angiogenesis at the tendon-bone interface. To determine if the increased osteointegration was translated into an improved pull-out mechanical strength property, the pull-out tensile strength of the LV-COX2-treated tendon grafts was determined with a pull-out mechanical testing assay. The LV-COX2 strategy yielded a significant improvement in the return of the pull-out strength of the tendon graft after 8 weeks. In conclusion, the COX2-based in vivo gene transfer strategy enhanced angiogenesis, osteointegration and improved return of the pull-out strength of the tendon graft. Thus, this strategy has great potential to be developed into an effective therapy to promote tendon-to-bone healing after tenodesis or related surgeries. PMID:24848992

Astronaut Bone Medical Standards Derived from Finite Element (FE) Models of QCT Scans from Population Studies

NASA Technical Reports Server (NTRS)

Sibonga, J. D.; Feiveson, A. H.

2014-01-01

This work was accomplished in support of the Finite Element [FE] Strength Task Group, NASA Johnson Space Center [JSC], Houston, TX. This group was charged with the task of developing rules for using finite-element [FE] bone-strength measures to construct operating bands for bone health that are relevant to astronauts following exposure to spaceflight. FE modeling is a computational tool used by engineers to estimate the failure loads of complex structures. Recently, some engineers have used this tool to characterize the failure loads of the hip in population studies that also monitored fracture outcomes. A Directed Research Task was authorized in July, 2012 to investigate FE data from these population studies to derive these proposed standards of bone health as a function of age and gender. The proposed standards make use of an FE-based index that integrates multiple contributors to bone strength, an expanded evaluation that is critical after an astronaut is exposed to spaceflight. The current index of bone health used by NASA is the measurement of areal BMD. There was a concern voiced by a research and clinical advisory panel that the sole use of areal BMD would be insufficient to fully evaluate the effects of spaceflight on the hip. Hence, NASA may not have a full understanding of fracture risk, both during and after a mission, and may be poorly estimating in-flight countermeasure efficacy. The FE Strength Task Group - composed of principal investigators of the aforementioned population studies and of FE modelers -donated some of its population QCT data to estimate of hip bone strength by FE modeling for this specific purpose. Consequently, Human Health Countermeasures [HHC] has compiled a dataset of FE hip strengths, generated by a single FE modeling approach, from human subjects (approx.1060) with ages covering the age range of the astronauts. The dataset has been analyzed to generate a set of FE strength cutoffs for the following scenarios: a) Qualify an applicant for astronaut candidacy, b) Qualify an astronaut for a long-duration (LD) mission, c) Qualify a veteran LD astronaut for a second LD mission, and d) Establish a non-permissible, minimum hip strength following a given mission architecture. This abstract will present the FE-based standards accepted by the FE Strength Task Group for its recommendation to HHC in January 2015.

Which is the preferred revision technique for loosened iliac screw? A novel technique of boring cement injection from the outer cortical shell.

PubMed

Yu, Bin-Sheng; Yang, Zhan-Kun; Li, Ze-Min; Zeng, Li-Wen; Wang, Li-Bing; Lu, William Weijia

2011-08-01

An in vitro biomechanical cadaver study. To evaluate the pull-out strength after 5000 cyclic loading among 4 revision techniques for the loosened iliac screw using corticocancellous bone, longer screw, traditional cement augmentation, and boring cement augmentation. Iliac screw loosening is still a clinical problem for lumbo-iliac fusion. Although many revision techniques using corticocancellous bone, larger screw, and polymethylmethacrylate (PMMA) augmentation were applied in repairing pedicle screw loosening, their biomechanical effects on the loosened iliac screw remain undetermined. Eight fresh human cadaver pelvises with the bone mineral density values ranging from 0.83 to 0.97 g/cm were adopted in this study. After testing the primary screw of 7.5 mm diameter and 70 mm length, 4 revision techniques were sequentially established and tested on the same pelvis as follows: corticocancellous bone, longer screw with 100 mm length, traditional PMMA augmentation, and boring PMMA augmentation. The difference of the boring technique from traditional PMMA augmentation is that PMMA was injected into the screw tract through 3 boring holes of outer cortical shell without removing the screw. On an MTS machine, after 5000 cyclic compressive loading of -200∼-500 N to the screw head, axial maximum pull-out strengths of the 5 screws were measured and analyzed. The pull-out strengths of the primary screw and 4 revised screws with corticocancellous bone, longer screw and traditional and boring PMMA augmentation were 1167 N, 361 N, 854 N, 1954 N, and 1820 N, respectively. Although longer screw method obtained significantly higher pull-out strength than corticocancellous bone (P<0.05), the revised screws using these 2 techniques exhibited notably lower pull-out strength than the primary screw and 2 PMMA-augmented screws (P<0.05). Either traditional or boring PMMA screw showed obviously higher pull-out strength than the primary screw (P<0.05); however, no significant difference of pull-out strength was detected between the 2 PMMA screws (P>0.05). Wadding corticocancellous bone and increasing screw length failed to provide sufficient anchoring strength for a loosened iliac screw; however, both traditional and boring PMMA-augmented techniques could effectively increase the fixation strength. On the basis of the viewpoint of minimal invasion, the boring PMMA augmentation may serve as a suitable salvage technique for iliac screw loosening.

The biological effects of tocotrienol on bone: a review on evidence from rodent models.

PubMed

Chin, Kok-Yong; Ima-Nirwana, Soelaiman

2015-01-01

Osteoporosis causes significant health care and economic burden to society, leading to a relentless search for effective preventive agents. Tocotrienol, a member of the vitamin E family, has demonstrated promising potential as an osteoporosis-preventing agent. This review summarizes evidence on the effects of tocotrienol on bone in animal models. Techniques used to examine the effects of tocotrienol on bone in animals included bone histomorphometry, X-ray microtomography, dual-energy X-ray absorptiometry, bone turnover markers, bone calcium content, and biomechanical strength. Tocotrienol was shown to improve osteoblast number, bone formation, mineral deposition, and bone microarchitecture in osteopenic rats. It also decreased osteoclast number and bone erosion in the rats. Tocotrienol supplementation resulted in an improvement in bone mineral density, although biomechanical strength was not significantly altered in the rats. The beneficial effects of tocotrienol on bone can be attributed to its role as an antioxidant, anti-inflammatory agent, suppressor of the mevalonate pathway, and modulator of genes favorable to bone formation.

The biological effects of tocotrienol on bone: a review on evidence from rodent models

PubMed Central

Chin, Kok-Yong; Ima-Nirwana, Soelaiman

2015-01-01

Osteoporosis causes significant health care and economic burden to society, leading to a relentless search for effective preventive agents. Tocotrienol, a member of the vitamin E family, has demonstrated promising potential as an osteoporosis-preventing agent. This review summarizes evidence on the effects of tocotrienol on bone in animal models. Techniques used to examine the effects of tocotrienol on bone in animals included bone histomorphometry, X-ray microtomography, dual-energy X-ray absorptiometry, bone turnover markers, bone calcium content, and biomechanical strength. Tocotrienol was shown to improve osteoblast number, bone formation, mineral deposition, and bone microarchitecture in osteopenic rats. It also decreased osteoclast number and bone erosion in the rats. Tocotrienol supplementation resulted in an improvement in bone mineral density, although biomechanical strength was not significantly altered in the rats. The beneficial effects of tocotrienol on bone can be attributed to its role as an antioxidant, anti-inflammatory agent, suppressor of the mevalonate pathway, and modulator of genes favorable to bone formation. PMID:25897211

Bone volume fraction and structural parameters for estimation of mechanical stiffness and failure load of human cancellous bone samples; in-vitro comparison of ultrasound transit time spectroscopy and X-ray μCT.

PubMed

Alomari, Ali Hamed; Wille, Marie-Luise; Langton, Christian M

2018-02-01

Conventional mechanical testing is the 'gold standard' for assessing the stiffness (N mm -1 ) and strength (MPa) of bone, although it is not applicable in-vivo since it is inherently invasive and destructive. The mechanical integrity of a bone is determined by its quantity and quality; being related primarily to bone density and structure respectively. Several non-destructive, non-invasive, in-vivo techniques have been developed and clinically implemented to estimate bone density, both areal (dual-energy X-ray absorptiometry (DXA)) and volumetric (quantitative computed tomography (QCT)). Quantitative ultrasound (QUS) parameters of velocity and attenuation are dependent upon both bone quantity and bone quality, although it has not been possible to date to transpose one particular QUS parameter into separate estimates of quantity and quality. It has recently been shown that ultrasound transit time spectroscopy (UTTS) may provide an accurate estimate of bone density and hence quantity. We hypothesised that UTTS also has the potential to provide an estimate of bone structure and hence quality. In this in-vitro study, 16 human femoral bone samples were tested utilising three techniques; UTTS, micro computed tomography (μCT), and mechanical testing. UTTS was utilised to estimate bone volume fraction (BV/TV) and two novel structural parameters, inter-quartile range of the derived transit time (UTTS-IQR) and the transit time of maximum proportion of sonic-rays (TTMP). μCT was utilised to derive BV/TV along with several bone structure parameters. A destructive mechanical test was utilised to measure the stiffness and strength (failure load) of the bone samples. BV/TV was calculated from the derived transit time spectrum (TTS); the correlation coefficient (R 2 ) with μCT-BV/TV was 0.885. For predicting mechanical stiffness and strength, BV/TV derived by both μCT and UTTS provided the strongest correlation with mechanical stiffness (R 2 =0.567 and 0.618 respectively) and mechanical strength (R 2 =0.747 and 0.736 respectively). When respective structural parameters were incorporated to BV/TV, multiple regression analysis indicated that none of the μCT histomorphometric parameters could improve the prediction of mechanical stiffness and strength, while for UTTS, adding TTMP to BV/TV increased the prediction of mechanical stiffness to R 2 =0.711 and strength to R 2 =0.827. It is therefore envisaged that UTTS may have the ability to estimate BV/TV along with providing an improved prediction of osteoporotic fracture risk, within routine clinical practice in the future. Copyright © 2017 Elsevier Inc. All rights reserved.

Evaluating the relationship between muscle and bone modeling response in older adults.

PubMed

Reider, Lisa; Beck, Thomas; Alley, Dawn; Miller, Ram; Shardell, Michelle; Schumacher, John; Magaziner, Jay; Cawthon, Peggy M; Barbour, Kamil E; Cauley, Jane A; Harris, Tamara

2016-09-01

Bone modeling, the process that continually adjusts bone strength in response to prevalent muscle-loading forces throughout an individual's lifespan, may play an important role in bone fragility with age. Femoral stress, an index of bone modeling response, can be estimated using measurements of DXA derived bone geometry and loading information incorporated into an engineering model. Assuming that individuals have adapted to habitual muscle loading forces, greater stresses indicate a diminished response and a weaker bone. The purpose of this paper was to evaluate the associations of lean mass and muscle strength with the femoral stress measure generated from the engineering model and to examine the extent to which lean mass and muscle strength account for variation in femoral stress among 2539 healthy older adults participating in the Health ABC study using linear regression. Mean femoral stress was higher in women (9.51, SD=1.85Mpa) than in men (8.02, SD=1.43Mpa). Percent lean mass explained more of the variation in femoral stress than did knee strength adjusted for body size (R(2)=0.187 vs. 0.055 in men; R(2)=0.237 vs. 0.095 in women). In models adjusted for potential confounders, for every percent increase in lean mass, mean femoral stress was 0.121Mpa lower (95% CI: -0.138, -0.104; p<0.001) in men and 0.139Mpa lower (95% CI: -0.158, -0.121; p<0.001) in women. The inverse association of femoral stress with lean mass and with knee strength did not differ by category of BMI. Results from this study provide insight into bone modeling differences as measured by femoral stress among older men and women and indicate that lean mass may capture elements of bone's response to load. Copyright © 2016 Elsevier Inc. All rights reserved.

Sensitivity Analysis of the Bone Fracture Risk Model

NASA Technical Reports Server (NTRS)

Lewandowski, Beth; Myers, Jerry; Sibonga, Jean Diane

2017-01-01

Introduction: The probability of bone fracture during and after spaceflight is quantified to aid in mission planning, to determine required astronaut fitness standards and training requirements and to inform countermeasure research and design. Probability is quantified with a probabilistic modeling approach where distributions of model parameter values, instead of single deterministic values, capture the parameter variability within the astronaut population and fracture predictions are probability distributions with a mean value and an associated uncertainty. Because of this uncertainty, the model in its current state cannot discern an effect of countermeasures on fracture probability, for example between use and non-use of bisphosphonates or between spaceflight exercise performed with the Advanced Resistive Exercise Device (ARED) or on devices prior to installation of ARED on the International Space Station. This is thought to be due to the inability to measure key contributors to bone strength, for example, geometry and volumetric distributions of bone mass, with areal bone mineral density (BMD) measurement techniques. To further the applicability of model, we performed a parameter sensitivity study aimed at identifying those parameter uncertainties that most effect the model forecasts in order to determine what areas of the model needed enhancements for reducing uncertainty. Methods: The bone fracture risk model (BFxRM), originally published in (Nelson et al) is a probabilistic model that can assess the risk of astronaut bone fracture. This is accomplished by utilizing biomechanical models to assess the applied loads; utilizing models of spaceflight BMD loss in at-risk skeletal locations; quantifying bone strength through a relationship between areal BMD and bone failure load; and relating fracture risk index (FRI), the ratio of applied load to bone strength, to fracture probability. There are many factors associated with these calculations including environmental factors, factors associated with the fall event, mass and anthropometric values of the astronaut, BMD characteristics, characteristics of the relationship between BMD and bone strength and bone fracture characteristics. The uncertainty in these factors is captured through the use of parameter distributions and the fracture predictions are probability distributions with a mean value and an associated uncertainty. To determine parameter sensitivity, a correlation coefficient is found between the sample set of each model parameter and the calculated fracture probabilities. Each parameters contribution to the variance is found by squaring the correlation coefficients, dividing by the sum of the squared correlation coefficients, and multiplying by 100. Results: Sensitivity analyses of BFxRM simulations of preflight, 0 days post-flight and 365 days post-flight falls onto the hip revealed a subset of the twelve factors within the model which cause the most variation in the fracture predictions. These factors include the spring constant used in the hip biomechanical model, the midpoint FRI parameter within the equation used to convert FRI to fracture probability and preflight BMD values. Future work: Plans are underway to update the BFxRM by incorporating bone strength information from finite element models (FEM) into the bone strength portion of the BFxRM. Also, FEM bone strength information along with fracture outcome data will be incorporated into the FRI to fracture probability.

Understanding the Structure of Bones

MedlinePlus

... bend. The same organization is true of bone. Collagen rods in bone are similar to the steel ... These minerals give the bones strength while the collagen rods provide resiliency. Diseases that interfere with the ...

Loss of bone strength in HLA-B27 transgenic rats is characterized by a high bone turnover and is mainly osteoclast-driven.

PubMed

Rauner, Martina; Thiele, Sylvia; Fert, Ingrid; Araujo, Luiza M; Layh-Schmitt, Gerlinde; Colbert, Robert A; Hofbauer, Christine; Bernhardt, Ricardo; Bürki, Alexander; Schwiedrzik, Jakob; Zysset, Philippe K; Pietschmann, Peter; Taurog, Joel D; Breban, Maxime; Hofbauer, Lorenz C

2015-06-01

Although osteopenia is frequent in spondyloarthritis (SpA), the underlying cellular mechanisms and association with other symptoms are poorly understood. This study aimed to characterize bone loss during disease progression, determine cellular alterations, and assess the contribution of inflammatory bowel disease (IBD) to bone loss in HLA-B27 transgenic rats. Bones of 2-, 6-, and 12-month-old non-transgenic, disease-free HLA-B7 and disease-associated HLA-B27 transgenic rats were examined using peripheral quantitative computed tomography, μCT, and nanoindentation. Cellular characteristics were determined by histomorphometry and ex vivo cultures. The impact of IBD was determined using [21-3 x 283-2]F1 rats, which develop arthritis and spondylitis, but not IBD. HLA-B27 transgenic rats continuously lost bone mass with increasing age and had impaired bone material properties, leading to a 3-fold decrease in bone strength at 12 months of age. Bone turnover was increased in HLA-B27 transgenic rats, as evidenced by a 3-fold increase in bone formation and a 6-fold increase in bone resorption parameters. Enhanced osteoclastic markers were associated with a larger number of precursors in the bone marrow and a stronger osteoclastogenic response to RANKL or TNFα. Further, IBD-free [21-3 x 283-2]F1 rats also displayed decreased total and trabecular bone density. HLA-B27 transgenic rats lose an increasing amount of bone density and strength with progressing age, which is primarily mediated via increased bone remodeling in favor of bone resorption. Moreover, IBD and bone loss seem to be independent features of SpA in HLA-B27 transgenic rats. Copyright © 2015 Elsevier Inc. All rights reserved.

Quantification of bone strength by intraoperative torque measurement: a technical note.

PubMed

Suhm, Norbert; Haenni, Markus; Schwyn, Ronald; Hirschmann, Michael; Müller, Andreas Marc

2008-06-01

Bone strength describes the resistance of bone against mechanical failure. Bone strength depends on both the amount of bone and the bone's quality, and the bone strength may be looked upon as a relevant parameter to judge an osteosynthesis' stability. Information about bone strength was barely available intraoperatively in the past. The previous work of our group reported on development and laboratory evaluation of mechanical torque measurement as a method for the intraoperative quantification of bone strength. With the clinical series presented here we intend to verify that the im gesamten Text DensiProbe instrumentation for intraoperative torque measurement and the related measurement method are eligible for intraoperative use based on the following criteria: application of the method may not create complications, the measurement can be performed by the surgeon himself and may only cause a limited increase in the procedure time. From December 2006 until May 2007 ten patients with a pertrochanteric femoral fracture or a lateral femoral neck fracture eligible for stabilization with DHS were included in the study after having received informed consent. Any medication and comorbidity that might have influenced bone quality or bone mineral density (BMD) in these patients was documented. Bone strength was intraoperatively measured with DensiProbe. Complications that were obviously related with torque measurement were documented as well as any deviation from the suggested procedure; 6 and 12 weeks postoperative follow-up included clinical and radiological examination. The time required for torque measurement, the overall operating time and the number of persons present in the operating room were protocolled. BMD values of the contralateral femoral neck were postoperatively assessed by dual energy X-ray absorptiometry (DEXA) and compared to intraoperative peak torque values measured by DensiProbe. No major complication was observed during intraoperative application of DensiProbe by trained surgeons. The unintended extraction of the guide wire together with the torque measurement probe was reported only once and is looked upon as a minor complication. Fracture healing was uneventful in all patients. The mean time for torque measurement was 2.35 +/- 0.9 min accounting for 2.2 +/- 1.1% of total surgery time. The presence of an additional person was not required to perform torque measurement but to protocol the data. There was a tendency towards correlation between BMD values of the femoral neck and intraoperative peak torque values. The data presented clearly indicate that the DensiProbe instrumentation and measurement principle are eligible for routine intraoperative use by trained surgeons. Interpretation of possible correlations between BMD values measured by means of DEXA and the Peak Torque values assessed by DensiProbe has to be considered very carefully, because BMD and Peak Torque analyse bone at a different scale. Only within the framework of a multicenter study it will be possible to include a sufficient number of patients for calculation of the methods' predictive value towards implant failure and to verify acceptance of the method by the surgeons.

Influence of lactation and pregnancy + lactation on mechanical properties and mineral content of the rat femur.

PubMed

Peng, T C; Kusy, R P; Garner, S C; Hirsch, P F; De Blanco, M C

1987-06-01

The quality of bone was assessed from femurs of rats both during lactation and after pregnancy + lactation. Mechanical properties of stiffness, strength, toughness, and ductility were measured, along with standard measurements of dry weight, ash weight, and total bone mineral. No changes occurred during the first week of lactation. During the second and third weeks of lactation all bone parameters except ductility decreased significantly. These data are consistent with bone losing mineral in order to supplement the dietary calcium intake necessary for milk production. In other experiments, femurs were collected from nulliparous rats and from rats that had previously undergone 1-3 pregnancy + lactations. The largest changes in bone mineral and mechanical properties occurred after a single pregnancy + lactation period, although significant further decreases in stiffness and strength occurred after the second pregnancy + lactation. No additional losses occurred following the third pregnancy + lactation. Even 5 months after only one pregnancy + lactation period, the bone quality was still impaired as all bone properties were lower than in nulliparous controls. Because the changes, especially stiffness and strength, were relatively larger than the changes in dry and ash weights of bone, measurements of these mechanical properties provide a more sensitive method to evaluate the quality of bone.

Effect of educational intervention using the Internet on quantitative ultrasound parameters in prevention of osteoporosis: a randomized controlled trial in young Japanese women.

PubMed

Asakawa, Kazumi; Koyama, Katsuhiro; Yamagata, Zentaro

2011-01-01

The objective of this study was to determine whether or not educational intervention using the Internet, to prevent osteoporosis, is able to increase bone strength in young women. Subjects were 253 healthy female university and junior college students aged 18-25 years. After initial measurements of bone stiffness index, a bone formation marker, and a bone absorption marker, the minimization method was used to allocate the subjects to an intervention group (n = 126) or a control group (n = 127) according to whether the measurements were above or below average. Subjects in the intervention group were instructed to perform osteoporosis prevention activities, ie, jump on the spot as high as possible ten times per day and increase calcium intake by 300 mg per day to a total of 800 mg or more per day on average. In addition, they were instructed to report the implementation status of the recommended measures via email. The researcher sent out information on osteoporosis and preventive behaviors to the subjects five times via email. A total of 182 subjects, comprising 87 (69.0%) in the intervention group and 95 (74.8%) in the control group, underwent remeasurement 6 months later. Of the subjects in the intervention group, 54 (42.9%) reported their daily additional calcium intake amount and number of jumps via email. The mean amount of additional calcium taken was 216.3 ± 85.9 mg per day, and mean number of jumps performed was 6.4 ± 4.2 per day. Subjects in the intervention group were further divided into an implementation group (n = 54), consisting of subjects who sent in reports and a nonimplementation group (n = 72) who did not. No significant difference was found among the groups for rate of change in bone stiffness index and speed of sound, but there was a significant difference for broadband ultrasound attenuation (BUA) (P = 0.017). Sheffe's multiple comparison test was performed using baseline body weight and BUA values as covariates, and revealed that the rate of decrease in bone strength in the control group was larger than that in the implementation group (P = 0.049). Health education for preventing osteoporosis via Internet email was performed over 6 months for women aged 18 to 25 and a comparison was performed between the intervention group and control group. The intervention consisted of high jumps on the spot (ten times a day), which reduced the drop in BUA, and thus indicates robustness of the trabecular structure. This suggests that a longer intervention period may maintain or improve bone strength.

Validity and test–retest reliability of a novel simple back extensor muscle strength test

PubMed Central

Harding, Amy T; Weeks, Benjamin Kurt; Horan, Sean A; Little, Andrew; Watson, Steven L; Beck, Belinda Ruth

2017-01-01

Objectives: To develop and determine convergent validity and reliability of a simple and inexpensive clinical test to quantify back extensor muscle strength. Methods: Two testing sessions were conducted, 7 days apart. Each session involved three trials of standing maximal isometric back extensor muscle strength using both the novel test and isokinetic dynamometry. Lumbar spine bone mineral density was examined by dual-energy X-ray absorptiometry. Validation was examined with Pearson correlations (r). Test–retest reliability was examined with intraclass correlation coefficients and limits of agreement. Pearson correlations and intraclass correlation coefficients are presented with corresponding 95% confidence intervals. Linear regression was used to examine the ability of peak back extensor muscle strength to predict indices of lumbar spine bone mineral density and strength. Results: A total of 52 healthy adults (26 men, 26 women) aged 46.4 ± 20.4 years were recruited from the community. A strong positive relationship was observed between peak back extensor strength from hand-held and isokinetic dynamometry (r = 0.824, p < 0.001). For the novel back extensor strength test, short- and long-term reliability was excellent (intraclass correlation coefficient = 0.983 (95% confidence interval, 0.971–0.990), p < 0.001 and intraclass correlation coefficient = 0.901 (95% confidence interval, 0.833–0.943), p < 0.001, respectively). Limits of agreement for short-term repeated back extensor strength measures with the novel back extensor strength protocol were −6.63 to 7.70 kg, with a mean bias of +0.71 kg. Back extensor strength predicted 11% of variance in lumbar spine bone mineral density (p < 0.05) and 9% of lumbar spine index of bone structural strength (p < 0.05). Conclusion: Our novel hand-held dynamometer method to determine back extensor muscle strength is quick, relatively inexpensive, and reliable; demonstrates initial convergent validity in a healthy population; and is associated with bone mass at a clinically important site. PMID:28255442

A novel use of 3D printing model demonstrates the effects of deteriorated trabecular bone structure on bone stiffness and strength.

PubMed

Barak, Meir Max; Black, Margaret Arielle

2018-02-01

Trabecular bone structure is crucial to normal mechanical behavior of bones. Studies have shown that osteoporosis negatively affects trabecular bone structure, mainly by reducing bone volume fraction (BV/TV) and thus increasing fracture risk. One major limitation in assessing and quantifying the effect of this structural deterioration is that no two trabecular structures are identical. Thus, when we compare a group of healthy bones against a different group of bones that experienced resorption (i.e. decreased BV/TV) we only discover an "average" mechanical effect. It is impossible to quantify the mechanical effect of individual structural deterioration for each sample, simply because we never have the same sample in both states (intact and deteriorated structure). 3D printing is a new technology that can assist in overcoming this issue. Here we report a preliminary study that compares a healthy 3D printed trabecular bone model with the same model after bone resorption was simulated. Since the deteriorated structural bone model is derived from the healthy one, it is possible to directly estimate (percentage wise) the decrease of tissue stiffness and strength as a result of bone resorption for this specific structure. Our results demonstrate that a relatively small decrease in BV/TV (about 8%) leads to a dramatic decrease in structural strength (24%) and structural stiffness (17%), (P < 0.01). Structural strength decreased from an average of 9.14 ± 2.85MPa to 6.97 ± 2.44MPa, while structural stiffness decreased from an average of 282.5 ± 63.4N/mm to 233.8 ± 51.2N/mm. This study demonstrates that 3D printing is a novel and valuable tool for quantifying the effect of structural deterioration on the mechanical properties of trabecular bone. In the future, this approach may help us attain better personal fracture risk assessments by CT scanning, 3D printing and mechanically testing individual bone replicas from patients suffering excessive bone resorption. Copyright © 2017 Elsevier Ltd. All rights reserved.

Age-related changes in bone strength from HR-pQCT derived microarchitectural parameters with an emphasis on the role of cortical porosity.

PubMed

Vilayphiou, Nicolas; Boutroy, Stephanie; Sornay-Rendu, Elisabeth; Van Rietbergen, Bert; Chapurlat, Roland

2016-02-01

The high resolution peripheral computed tomography (HR-pQCT) technique has seen recent developments with regard to the assessment of cortical porosity. In this study, we investigated the role of cortical porosity on bone strength in a large cohort of women. The distal radius and distal tibia were scanned by HR-pQCT. We assessed bone strength by estimating the failure load by microfinite element analysis (μFEA), with isotropic and homogeneous material properties. We built a multivariate model to predict it, using a few microarchitecture variables including cortical porosity. Among 857 Caucasian women analyzed with μFEA, we found that cortical and trabecular properties, along with the failure load, impaired slightly with advancing age in premenopausal women, the correlations with age being modest, with |rage| ranging from 0.14 to 0.38. After the onset of the menopause, those relationships with age were stronger for most parameters at both sites, with |rage| ranging from 0.10 to 0.64, notably for cortical porosity and failure load, which were markedly deteriorated with increasing age. Our multivariate model using microarchitecture parameters revealed that cortical porosity played a significant role in bone strength prediction, with semipartial r(2)=0.22 only at the tibia in postmenopausal women. In conclusion, in our large cohort of women, we observed a small decline of bone strength at the tibia before the onset of menopause. We also found an age-related increase of cortical porosity at both scanned sites in premenopausal women. In postmenopausal women, the relatively high increase of cortical porosity accounted for the decline in bone strength only at the tibia. Copyright © 2015 Elsevier Inc. All rights reserved.

Impact of stress-induced diabetes on outcomes in severely burned children.

PubMed

Finnerty, Celeste C; Ali, Arham; McLean, Josef; Benjamin, Nicole; Clayton, Robert P; Andersen, Clark R; Mlcak, Ronald P; Suman, Oscar E; Meyer, Walter; Herndon, David N

2014-04-01

Post-burn hyperglycemia leads to graft failure, multiple organ failure, and death. A hyperinsulinemic-euglycemic clamp is used to keep serum glucose between 60 and 110 mg/dL. Because of frequent hypoglycemic episodes, a less-stringent sliding scale insulin protocol is used to maintain serum glucose levels between 80 and 160 mg/dL after elevations >180 mg/dL. We randomized pediatric patients with massive burns into 2 groups, patients receiving sliding scale insulin to lower blood glucose levels (n = 145) and those receiving no insulin (n = 98), to determine the differences in morbidity and mortality. Patients 0 to 18 years old with burns covering ≥ 30% of the total body surface area and not randomized to receive anabolic agents were included in this study. End points included glucose levels, infections, resting energy expenditure, lean body mass, bone mineral content, fat mass, muscle strength, and serum inflammatory cytokines, hormones, and liver enzymes. Maximal glucose levels occurred within 6 days of burn injury. Blood glucose levels were age dependent, with older children requiring more insulin (p < 0.05). Daily maximum and daily minimum, but not 6 am, glucose levels were significantly different based on treatment group (p < 0.05). Insulin significantly increased resting energy expenditure and improved bone mineral content (p < 0.05). Each additional wound infection increased incidence of hyperglycemia (p = 0.004). There was no mortality in patients not receiving insulin, only in patients who received insulin (p < 0.004). Muscle strength was increased in patients receiving insulin (p < 0.05). Burn-induced hyperglycemia develops in a subset of severely burned children. Length of stay was reduced in the no insulin group, and there were no deaths in this group. Administration of insulin positively impacted bone mineral content and muscle strength, but increased resting energy expenditure, hypoglycemic episodes, and mortality. New glucose-lowering strategies might be needed. Copyright © 2014 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Women with previous stress fractures show reduced bone material strength

PubMed Central

Duarte Sosa, Daysi; Fink Eriksen, Erik

2016-01-01

Background and purpose — Bone fragility is determined by bone mass, bone architecture, and the material properties of bone. Microindentation has been introduced as a measurement method that reflects bone material properties. The pathogenesis of underlying stress fractures, in particular the role of impaired bone material properties, is still poorly understood. Based on the hypothesis that impaired bone material strength might play a role in the development of stress fractures, we used microindentation in patients with stress fractures and in controls. Patients and methods — We measured bone material strength index (BMSi) by microindentation in 30 women with previous stress fractures and in 30 normal controls. Bone mineral density by DXA and levels of the bone markers C-terminal cross-linking telopeptide of type-1 collagen (CTX) and N-terminal propeptide of type-1 procollagen (P1NP) were also determined. Results — Mean BMSi in stress fracture patients was significantly lower than in the controls (SD 72 (8.7) vs. 77 (7.2); p = 0.02). The fracture subjects also had a significantly lower mean bone mineral density (BMD) than the controls (0.9 (0.02) vs. 1.0 (0.06); p = 0.03). Bone turnover—as reflected in serum levels of the bone marker CTX—was similar in both groups, while P1NP levels were significantly higher in the women with stress fractures (55 μg/L vs. 42 μg/L; p = 0.03). There was no correlation between BMSi and BMD or bone turnover. Interpretation — BMSi was inferior in patients with previous stress fracture, but was unrelated to BMD and bone turnover. The lower values of BMSi in patients with previous stress fracture combined with a lower BMD may contribute to the increased propensity to develop stress fractures in these patients. PMID:27321443

The Biomechanical Testing for the Assessment of Bone Quality in an Experimental Model of Chronic Kidney Disease.

PubMed

Oksztulska-Kolanek, Ewa; Znorko, Beata; Michałowska, Małgorzata; Pawlak, Krystyna

2016-01-01

Mineral metabolism disturbances are common in chronic kidney disease (CKD) and have been classified as a new clinical entity, also known as CKD-mineral and bone disorders (CKD-MBD). A decrease in the bone strength, whose clinical manifestation is a tendency for fracture, has been recognized as an important component of CKD-MBD. Because of ethical issues, measurements of the bone strength in the human body are usually limited to noninvasive techniques, such as radiography, dual-energy X-ray absorptiometry and the assays of bone turnover biomarkers. However, it has been postulated recently that the evidence concerning bone strength based solely on the determination of the bone quantity may be insufficient and that bone quality should also be examined. In this regard, an animal model of CKD can represent an experimental tool to test the effectiveness of new therapeutic strategies. Despite the many available methods that are used to diagnose metabolic bone disorders and predict fracture risk especially in small rodents with CKD, it turns out that the most appropriate are biomechanical tests, which can provide information about the structural and material properties of bone. The present review summarizes and discusses the principles for carrying out selected biomechanical tests (3-point bending test and compression test) and their application in clinical practice. © 2015 S. Karger AG, Basel.

The Skeletal Biology of Hibernating Woodchucks (Marmota monax)

NASA Astrophysics Data System (ADS)

Doherty, Alison H.

Long periods of inactivity in most mammals lead to significant bone loss that may not be completely recovered during an individual's lifetime regardless of future activity. Extended bouts of inactivity are the norm for hibernating mammals. It remains largely unknown, however, how these animals avoid adversely affecting bone, their quality, and ultimately survival given the challenges posed to their skeletons by inactivity and nutritional deprivation during hibernation. The primary goal of this project was to identify the physiological mechanisms regulating bone density, area and strength during extended periods of annual inactivity in hibernating woodchucks (Marmota monax). The overall hypothesis that bone integrity is unaffected by several months of inactivity during hibernation in woodchucks was tested across multiple levels of biological function. To gain a holistic assessment of seasonal bone integrity, the locomotor behavior and estimated stresses acting on woodchuck bones were investigated in conjunction with computed tomography scans and three-point bending tests to determine bone density, geometry, and mechanical properties of the long bones throughout the year. In addition, serum protein expression was examined to ascertain bone resorption and formation processes indicative of overall annual skeletal health. It was determined that woodchucks avoid significant changes in gait preference, but experience a decrease in bending stresses acting on distal limb bones following hibernation. Computed tomography scans indicated that bone mass, distribution, and trabecular structure are maintained in these animals throughout the year. Surprisingly, cortical density increased significantly posthibernation. Furthermore, three-point bending tests revealed that although less stiff, woodchuck femora were just as tough during the hibernation season, unlike brittle bones associated with osteoporosis. Finally, bone serum markers suggested a net maintenance of bone resorption and formation processes throughout the year. Taken together, these findings strongly suggest that woodchucks do not lose bone to the extent that would be expected from a non-hibernating animal during four months of inactivity. It is concluded that bone integrity is not adversely affected by hibernation in woodchucks. The results of this work have several broader implications toward skeletal biology research, the evolution of skeletal plasticity, and biomedical applications to osteoporosis prevention and treatment.

Association of Insulin Resistance with Bone Strength and Bone Turnover in Menopausal Chinese-Singaporean Women without Diabetes

PubMed Central

Kalimeri, Maria; Leek, Francesca; Wang, Nan Xin; Koh, Huann Rong; Totman, John J.

2018-01-01

Insulin resistance (IR) is accompanied by increased areal or volumetric bone mineral density (aBMD or vBMD), but also higher fracture risk. Meanwhile, imbalances in bone health biomarkers affect insulin production. This study investigates the effect of IR on proximal femur and lumbar spine BMD, femoral neck bending, compressive and impact strength indices (Composite Strength Indices) and circulating levels of parathyroid hormone (PTH), C-telopeptide of Type I collagen (CTx-1) and 25(OH) Vitamin D3, in a cohort of 97 healthy, non-obese, menopausal Chinese-Singaporean women. Lumbar spine aBMD was inversely associated with IR and dependent on lean body mass (LBM) and age. No such associations were found for vBMD of the third lumbar vertebra, aBMD and vBMD of the proximal femur, or circulating levels of PTH, CTx-1 and 25(OH) Vitamin D3. Composite Strength Indices were inversely associated with IR and independent of LBM, but after adjusting for fat mass and age, this association remained valid only for the impact strength index. Composite Strength Indices were significantly lower in participants with a high degree of IR. Our findings on IR and Composite Strength Indices relationships were in agreement with previous studies on different cohorts, but those on IR and BMD associations were not. PMID:29710852

Musculoskeletal strength, balance performance, and self-efficacy in elderly ving tsun chinese martial art practitioners: implications for fall prevention.

PubMed

Fong, Shirley S M; Ng, Shamay S M; Liu, Karen P Y; Pang, Marco Y C; Lee, H W; Chung, Joanne W Y; Lam, Priscillia L; Guo, X

2014-01-01

Objectives. To (1) compare the bone strength, lower limb muscular strength, functional balance performance, and balance self-efficacy between Ving Tsun (VT) martial art practitioners and nonpractitioners and (2) identify the associations between lower limb muscular strength, functional balance performance, and balance self-efficacy among the VT-trained participants. Methods. Thirty-five VT practitioners (mean age ± SD = 62.7 ± 13.3 years) and 49 nonpractitioners (mean age ± SD = 65.9 ± 10.5 years) participated in the study. The bone strength of the distal radius, lower limb muscular strength, functional balance performance, and balance self-efficacy were assessed using an ultrasound bone sonometer, the five times sit-to-stand test (FTSTS), the Berg balance scale (BBS), and the Chinese version of the activities-specific balance confidence scale, respectively. A multivariate analysis of covariance was performed to compare all the outcome variables between the two groups. Results. Elderly VT practitioners had higher radial bone strength on the dominant side (P < 0.05), greater lower limb muscular strength (P = 0.001), better functional balance performance (P = 0.003), and greater balance confidence (P < 0.001) than the nonpractitioners. Additionally, only the FTSTS time revealed a significant association with the BBS score (r = -0.575,  P = 0.013). Conclusions. VT may be a suitable health-maintenance exercise for the elderly. Our findings may inspire the development of VT fall-prevention exercises for the community-dwelling healthy elderly.

Musculoskeletal Strength, Balance Performance, and Self-Efficacy in Elderly Ving Tsun Chinese Martial Art Practitioners: Implications for Fall Prevention

PubMed Central

Fong, Shirley S. M.; Ng, Shamay S. M.; Liu, Karen P. Y.; Pang, Marco Y. C.; Lee, H. W.; Chung, Joanne W. Y.; Lam, Priscillia L.; Guo, X.

2014-01-01

Objectives. To (1) compare the bone strength, lower limb muscular strength, functional balance performance, and balance self-efficacy between Ving Tsun (VT) martial art practitioners and nonpractitioners and (2) identify the associations between lower limb muscular strength, functional balance performance, and balance self-efficacy among the VT-trained participants. Methods. Thirty-five VT practitioners (mean age ± SD = 62.7 ± 13.3 years) and 49 nonpractitioners (mean age ± SD = 65.9 ± 10.5 years) participated in the study. The bone strength of the distal radius, lower limb muscular strength, functional balance performance, and balance self-efficacy were assessed using an ultrasound bone sonometer, the five times sit-to-stand test (FTSTS), the Berg balance scale (BBS), and the Chinese version of the activities-specific balance confidence scale, respectively. A multivariate analysis of covariance was performed to compare all the outcome variables between the two groups. Results. Elderly VT practitioners had higher radial bone strength on the dominant side (P < 0.05), greater lower limb muscular strength (P = 0.001), better functional balance performance (P = 0.003), and greater balance confidence (P < 0.001) than the nonpractitioners. Additionally, only the FTSTS time revealed a significant association with the BBS score (r = −0.575,  P = 0.013). Conclusions. VT may be a suitable health-maintenance exercise for the elderly. Our findings may inspire the development of VT fall-prevention exercises for the community-dwelling healthy elderly. PMID:25530782

Female Mice Lacking Estrogen Receptor-α in Hypothalamic Proopiomelanocortin (POMC) Neurons Display Enhanced Estrogenic Response on Cortical Bone Mass.

PubMed

Farman, H H; Windahl, S H; Westberg, L; Isaksson, H; Egecioglu, E; Schele, E; Ryberg, H; Jansson, J O; Tuukkanen, J; Koskela, A; Xie, S K; Hahner, L; Zehr, J; Clegg, D J; Lagerquist, M K; Ohlsson, C

2016-08-01

Estrogens are important regulators of bone mass and their effects are mainly mediated via estrogen receptor (ER)α. Central ERα exerts an inhibitory role on bone mass. ERα is highly expressed in the arcuate (ARC) and the ventromedial (VMN) nuclei in the hypothalamus. To test whether ERα in proopiomelanocortin (POMC) neurons, located in ARC, is involved in the regulation of bone mass, we used mice lacking ERα expression specifically in POMC neurons (POMC-ERα(-/-)). Female POMC-ERα(-/-) and control mice were ovariectomized (OVX) and treated with vehicle or estradiol (0.5 μg/d) for 6 weeks. As expected, estradiol treatment increased the cortical bone thickness in femur, the cortical bone mechanical strength in tibia and the trabecular bone volume fraction in both femur and vertebrae in OVX control mice. Importantly, the estrogenic responses were substantially increased in OVX POMC-ERα(-/-) mice compared with the estrogenic responses in OVX control mice for cortical bone thickness (+126 ± 34%, P < .01) and mechanical strength (+193 ± 38%, P < .01). To test whether ERα in VMN is involved in the regulation of bone mass, ERα was silenced using an adeno-associated viral vector. Silencing of ERα in hypothalamic VMN resulted in unchanged bone mass. In conclusion, mice lacking ERα in POMC neurons display enhanced estrogenic response on cortical bone mass and mechanical strength. We propose that the balance between inhibitory effects of central ERα activity in hypothalamic POMC neurons in ARC and stimulatory peripheral ERα-mediated effects in bone determines cortical bone mass in female mice.

Theoretical prediction of pullout strengths for dental and orthopaedic screws with conical profile and buttress threads.

PubMed

Shih, Kao-Shang; Hou, Sheng-Mou; Lin, Shang-Chih

2017-12-01

The pullout strength of a screw is an indicator of how secure bone fragments are being held in place. Such bone-purchasing ability is sensitive to bone quality, thread design, and the pilot hole, and is often evaluated by experimental and numerical methods. Historically, there are some mathematical formulae to simulate the screw withdrawal from the synthetic bone. There are great variations in screw specifications. However, extensive investigation of the correlation between experimental and analytical results has not been reported in literature. Referring to the literature formulae, this study aims to evaluate the differences in the calculated pullout strengths. The pullout tests of the surgical screws are measured and the sawbone is used as the testing block. The absolute errors and correlation coefficients of the experimental and analytical results are calculated as the comparison baselines of the formulae. The absolute error of the dental, traumatic, and spinal groups are 21.7%, 95.5%, and 37.0%, respectively. For the screws with a conical profile and/or tiny threads, the calculated and measured results are not well correlated. The formulae are not accurate indicators of the pullout strengths of the screws where the design parameters are slightly varied. However, the experimental and numerical results are highly correlated for the cylindrical screws. The pullout strength of a conical screw is higher than that of its counterpart, but all formulae consistently predict the opposite results. In general, the bony purchase of the buttress threads is securer than that of the symmetric thread. An absolute error of up to 51.4% indicates the theoretical results cannot predict the actual value of the pullout strength. Only thread diameter, pitch, and depth are considered in the investigated formulae. The thread profile and shape should be formulated to modify the slippage mechanism at the bone-screw interfaces and simulate the strength change in the squeezed bones, especially for the conical screw. Copyright © 2017. Published by Elsevier B.V.

Excercise Within LBNP as an Artificial Gravity Countermeasure

NASA Technical Reports Server (NTRS)

Hargens, A. R.; Watenpaugh, D. E.; Lee, S. M. C.; Meyer, R. S.; Macias, B.; Tanaka, K.; Kimura, S.; Steinbach, G.; Groppo, E.; Khalili, N.;

Effect of long-term impact-loading on mass, size, and estimated strength of humerus and radius of female racquet-sports players: a peripheral quantitative computed tomography study between young and old starters and controls.

PubMed

Kontulainen, Saija; Sievänen, Harri; Kannus, Pekka; Pasanen, Matti; Vuori, Ilkka

2002-12-01

Bone characteristics of the humeral shaft and distal radius were measured from 64 female tennis and squash players and their 27 age-, height-, and weight-matched controls with peripheral quantitative tomography (pQCT) and DXA. The players were divided into two groups according to the starting age of their tennis or squash training (either before or after menarche) to examine the possible differences in the loading-induced changes in bone structure and volumetric density. The used pQCT variables were bone mineral content (BMC), total cross-sectional area (TotA) of bone, cross-sectional area of the marrow cavity (CavA) and that of the cortical bone (CoA), cortical wall thickness (CWT), volumetric density of the cortical bone (CoD) and trabecular bone (TrD), and torsional bone strength index (BSIt) for the shaft, and compressional bone strength index (BSIc) for the bone end. These bone strength indices were compared with the DXA-derived areal bone mineral density (aBMD) to assess how well the latter represents the effect of mechanical loading on apparent bone strength. At the humeral shaft, the loaded arm's greater BMC (an average 19% side-to-side difference in young starters and 9% in old starters) was caused by an enlarged cortex (CoA; side-to-side differences 20% and 9%, respectively). The loaded humerus seemed to have grown periosteally (the CavA did not differ between the sites) leading to 26% and 11% side-to-side BSIt difference in the young and old starters, respectively. CoD was equal between the arms (-1% difference in both player groups). The side-to-side differences in the young starters' BMC, CoA, TotA, CWT, and BSIt were 8-22% higher than those of the controls and 8-14% higher than those of the old starters. Old starters' BMC, CoA, and BSIt side-to-side differences were 6-7% greater than those in the controls. The DXA-derived side-to-side aBMD difference was 7% greater in young starters compared with that of the old starters and 14% compared with that in controls, whereas the difference between old starters and controls was 6%, in favor of the former. All these between-group differences were statistically significant. At the distal radius, the player groups differed significantly from controls in the side-to-side BMC, TrD, and aBMD differences only; the young starters' BMC difference was 9% greater, TrD and aBMD differences were 5% greater than those in the controls, and the old starters' TrD and aBMD differences were both 7% greater than those in the controls. In summary, in both of the female player groups the structural adaptation of the humeral shaft to long-term loading seemed to be achievedthrough periosteal enlargement of the bone cortex although this adaptation was clearly better in the young starters. Exercise-induced cortical enlargement was not so clear at the distal radius (a trabecular bone site), and the study suggested that at long bone ends also the TrD could be a modifiable factor to build a stronger bone structure. The conventional DXA-based aBMD measurement detected the intergroup differences in the exercise-induced bone gains, although, measuring two dimensions of bone only, it seemed to underestimate the effect of exercise on the apparent bone strength, especially if the playing had been started during the growing years.

Effect of whole-body vibration on bone properties in aging mice.

PubMed

Wenger, Karl H; Freeman, James D; Fulzele, Sadanand; Immel, David M; Powell, Brian D; Molitor, Patrick; Chao, Yuh J; Gao, Hong-Sheng; Elsalanty, Mohammed; Hamrick, Mark W; Isales, Carlos M; Yu, Jack C

2010-10-01

Recent studies suggest that whole-body vibration (WBV) can improve measures of bone health for certain clinical conditions and ages. In the elderly, there also is particular interest in assessing the ability of physical interventions such as WBV to improve coordination, strength, and movement speed, which help prevent falls and fractures and maintain ambulation for independent living. The current study evaluated the efficacy of WBV in an aging mouse model. Two levels of vibration--0.5 and 1.5g--were applied at 32Hz to CB57BL/6 male mice (n=9 each) beginning at age 18 months and continuing for 12 weeks, 30 min/day, in a novel pivoting vibration device. Previous reports indicate that bone parameters in these mice begin to decrease substantially at 18 months, equivalent to mid-fifties for humans. Micro-computed tomography (micro-CT) and biomechanical assessments were made in the femur, radius, and lumbar vertebra to determine the effect of these WBV magnitudes and durations in the aging model. Sera also were collected for analysis of bone formation and breakdown markers. Mineralizing surface and cell counts were determined histologically. Bone volume in four regions of the femur did not change significantly, but there was a consistent shift toward higher mean density in the bone density spectrum (BDS), with the two vibration levels producing similar results. This new parameter represents an integral of the conventional density histogram. The amount of high density bone statistically improved in the head, neck, and diaphysis. Biomechanically, there was a trend toward greater stiffness in the 1.5 g group (p=0.139 vs. controls in the radius), and no change in strength. In the lumbar spine, no differences were seen due to vibration. Both vibration groups significantly reduced pyridinoline crosslinks, a collagen breakdown marker. They also significantly increased dynamic mineralization, MS/BS. Furthermore, osteoclasts were most numerous in the 1.5 g group (p≤ 0.05). These findings suggest that some benefits of WBV found in previous studies of young and mature rodent models may extend to an aging population. Density parameters indicated 0.5 g was more effective than 1.5 g. Serological markers, by contrast, favored 1.5 g, while biomechanically and histologically the results were mixed. Although the purported anabolic effect of WBV on bone homeostasis may depend on location and the parameter of interest, this emerging therapy at a minimum does not appear to compromise bone health by the measures studied here. Copyright © 2010 Elsevier Inc. All rights reserved.

Dramatic Improvement of the Mechanical Strength of Silane-Modified Hydroxyapatite–Gelatin Composites via Processing with Cosolvent

PubMed Central

2018-01-01

Bone tissue engineering (BTE) requires a sturdy biomaterial for scaffolds for restoration of large bone defects. Ideally, the scaffold should have a mechanical strength comparable to the natural bone in the implanted site. We show that adding cosolvent during the processing of our previously developed composite of hydroxyapatite–gelatin with a silane cross-linker can significantly affect its mechanical strength. When processed with tetrahydrofuran (THF) as the cosolvent, the new hydroxyapatite–gelatin composite can demonstrate almost twice the compressive strength (97 vs 195 MPa) and biaxial flexural strength (222 vs 431 MPa) of the previously developed hydroxyapatite–gelatin composite (i.e., processed without THF), respectively. We further confirm that this mechanical strength improvement is due to the improved morphology of both the enTMOS network and the composite. Furthermore, the addition of cosolvents does not appear to negatively impact the cell viability. Finally, the porous scaffold can be easily fabricated, and its compressive strength is around 11 MPa under dry conditions. All these results indicate that this new hydroxyapatite–gelatin composite is a promising material for BTE application. PMID:29623305

Proximal Femur Mechanical Adaptation to Weight Gain in Late Adolescence: A Six-Year Longitudinal Study

PubMed Central

Petit, Moira A; Beck, Thomas J; Hughes, Julie M; Lin, Hung-Mo; Bentley, Christy; Lloyd, Tom

2008-01-01

The effect of weight gain in late adolescence on bone is not clear. Young women who consistently gained weight (n = 23) from 17 to 22 yr of age had increased BMD but a lack of subperiosteal expansion compared with stable weight peers (n = 48). Bone strength increased appropriately for lean mass in both groups but decreased relative to body weight in weight gainers, suggesting increased bone fragility in weight gainers. Introduction Weight gain leading to obesity often starts in adolescence, yet little is known about its effects on bone. We used longitudinal data to examine the effects of weight gain in late adolescence (from 17 to 22 yr of age) on proximal femur BMD, geometry, and estimates of bending strength. Materials and Methods Participants were classified as either weight gainers (WG, n = 23) or stable weight (SW, n = 48) using a random coefficients model. Weight gainers had positive increases in weight (p < 0.05) at each clinic visit from age 17 onward. Proximal femur DXA scans (Hologic QDR 2000) taken annually from 17 to 22 yr of age were analyzed for areal BMD (g/cm2), subperiosteal width (cm), and bone cross-sectional area (CSA) at the proximal femoral shaft. Cortical thickness was measured, and section modulus (Z, cm3) was calculated as a measure of bone bending strength. Total body lean (g) and fat (g) mass were measured from DXA total body scans. Results Over ages 17–22, height remained stable in both groups. Weight remained static in the SW group but increased 14% on average in the WG group (p < 0.05). After controlling for age 17 baseline values, WG had higher BMD (+2.6%), thicker cortices (+3.6%), and greater bone CSA (+2.3%). Increased BMD did not translate to greater increases in bone bending strength (Z). The SW group achieved similar gains in Z by greater subperiosteal expansion. Bone strength index (SI = Z/height) normalized for body weight remained constant in the SW group but decreased significantly in the WG group. In contrast, SI normalized to lean mass did not change over time in either group. Other variables including physical activity, nutrition, and hormone levels (estradiol, testosterone, cortisol) did not differ significantly between groups. Conclusions These data suggest that weight gain in late adolescence may inhibit the periosteal expansion known to normally occur throughout life in long bones, resulting in decreased bone strength relative to body weight. PMID:17937533

Treatment with soluble activin type IIB-receptor improves bone mass and strength in a mouse model of Duchenne muscular dystrophy.

PubMed

Puolakkainen, Tero; Ma, Hongqian; Kainulainen, Heikki; Pasternack, Arja; Rantalainen, Timo; Ritvos, Olli; Heikinheimo, Kristiina; Hulmi, Juha J; Kiviranta, Riku

2017-01-19

Inhibition of activin/myostatin pathway has emerged as a novel approach to increase muscle mass and bone strength. Duchenne muscular dystrophy (DMD) is a neuromuscular disorder that leads to progressive muscle degeneration and also high incidence of fractures. The aim of our study was to test whether inhibition of activin receptor IIB ligands with or without exercise could improve bone strength in the mdx mouse model for DMD. Thirty-two mdx mice were divided to running and non-running groups and to receive either PBS control or soluble activin type IIB-receptor (ActRIIB-Fc) once weekly for 7 weeks. Treatment of mdx mice with ActRIIB-Fc resulted in significantly increased body and muscle weights in both sedentary and exercising mice. Femoral μCT analysis showed increased bone volume and trabecular number (BV/TV +80%, Tb.N +70%, P < 0.05) in both ActRIIB-Fc treated groups. Running also resulted in increased bone volume and trabecular number in PBS-treated mice. However, there was no significant difference in trabecular bone structure or volumetric bone mineral density between the ActRIIB-Fc and ActRIIB-Fc-R indicating that running did not further improve bone structure in ActRIIB-Fc-treated mice. ActRIIB-Fc increased bone mass also in vertebrae (BV/TV +20%, Tb.N +30%, P < 0.05) but the effects were more modest. The number of osteoclasts was decreased in histological analysis and the expression of several osteoblast marker genes was increased in ActRIIB-Fc treated mice suggesting decreased bone resorption and increased bone formation in these mice. Increased bone mass in femurs translated into enhanced bone strength in biomechanical testing as the maximum force and stiffness were significantly elevated in ActRIIB-Fc-treated mice. Our results indicate that treatment of mdx mice with the soluble ActRIIB-Fc results in a robust increase in bone mass, without any additive effect by voluntary running. Thus ActRIIB-Fc could be an attractive option in the treatment of musculoskeletal disorders.

Virtual estimates of fastening strength for pedicle screw implantation procedures

NASA Astrophysics Data System (ADS)

Linte, Cristian A.; Camp, Jon J.; Augustine, Kurt E.; Huddleston, Paul M.; Robb, Richard A.; Holmes, David R.

2014-03-01

Traditional 2D images provide limited use for accurate planning of spine interventions, mainly due to the complex 3D anatomy of the spine and close proximity of nerve bundles and vascular structures that must be avoided during the procedure. Our previously developed clinician-friendly platform for spine surgery planning takes advantage of 3D pre-operative images, to enable oblique reformatting and 3D rendering of individual or multiple vertebrae, interactive templating, and placement of virtual pedicle implants. Here we extend the capabilities of the planning platform and demonstrate how the virtual templating approach not only assists with the selection of the optimal implant size and trajectory, but can also be augmented to provide surrogate estimates of the fastening strength of the implanted pedicle screws based on implant dimension and bone mineral density of the displaced bone substrate. According to the failure theories, each screw withstands a maximum holding power that is directly proportional to the screw diameter (D), the length of the in-bone segm,ent of the screw (L), and the density (i.e., bone mineral density) of the pedicle body. In this application, voxel intensity is used as a surrogate measure of the bone mineral density (BMD) of the pedicle body segment displaced by the screw. We conducted an initial assessment of the developed platform using retrospective pre- and post-operative clinical 3D CT data from four patients who underwent spine surgery, consisting of a total of 26 pedicle screws implanted in the lumbar spine. The Fastening Strength of the planned implants was directly assessed by estimating the intensity - area product across the pedicle volume displaced by the virtually implanted screw. For post-operative assessment, each vertebra was registered to its homologous counterpart in the pre-operative image using an intensity-based rigid registration followed by manual adjustment. Following registration, the Fastening Strength was computed for each displaced bone segment. According to our preliminary clinical study, a comparison between Fastening Strength, displaced bone volume and mean voxel intensity showed similar results (p < 0.1) between the virtually templated plans and the post-operative outcome following the traditional clinical approach. This study has demonstrated the feasibility of the platform in providing estimates the pedicle screw fastening strength via virtual implantation, given the intrinsic vertebral geometry and bone mineral density, enabling the selection of the optimal implant dimension adn trajectory for improved strength.

Surface pretreatments for medical application of adhesion

PubMed Central

Erli, Hans J; Marx, Rudolf; Paar, Othmar; Niethard, Fritz U; Weber, Michael; Wirtz, Dieter C

2003-01-01

Medical implants and prostheses (artificial hips, tendono- and ligament plasties) usually are multi-component systems that may be machined from one of three material classes: metals, plastics and ceramics. Typically, the body-sided bonding element is bone. The purpose of this contribution is to describe developments carried out to optimize the techniques , connecting prosthesis to bone, to be joined by an adhesive bone cement at their interface. Although bonding of organic polymers to inorganic or organic surfaces and to bone has a long history, there remains a serious obstacle in realizing long-term high-bonding strengths in the in vivo body environment of ever present high humidity. Therefore, different pretreatments, individually adapted to the actual combination of materials, are needed to assure long term adhesive strength and stability against hydrolysis. This pretreatment for metal alloys may be silica layering; for PE-plastics, a specific plasma activation; and for bone, amphiphilic layering systems such that the hydrophilic properties of bone become better adapted to the hydrophobic properties of the bone cement. Amphiphilic layering systems are related to those developed in dentistry for dentine bonding. Specific pretreatment can significantly increase bond strengths, particularly after long term immersion in water under conditions similar to those in the human body. The bond strength between bone and plastic for example can be increased by a factor approaching 50 (pealing work increasing from 30 N/m to 1500 N/m). This review article summarizes the multi-disciplined subject of adhesion and adhesives, considering the technology involved in the formation and mechanical performance of adhesives joints inside the human body. PMID:14561228

How bone forms in large cancellous defects: critical analysis based on experimental work and literature.

PubMed

Draenert, K; Draenert, M; Erler, M; Draenert, A; Draenert, Y

2011-09-01

The behaviour of physiological biomaterials, β-tricalciumphosphate and hydroxyapatite, is analysed based on current literature and our own experimental work. The properties of graft substitutes based on ceramic materials are clearly defined according to their scientific efficiency. The strength of the materials and their biodegradability are still not fully evaluated. Strength and degradability have a direct proportional relationship and are considered the most efficient way to be adapted by their properties to the needs for the treatment of bone defects. New technologies for the manufacturing process are presented that increase those properties and thus open up new indications and easier application of the ceramic materials. The implantation process as well is carefully validated by animal experiments to avoid failures. Based on the experiments, a completely new approach is defined as to how primary bone formation with osteoconductive ceramics can be achieved. The milestones in that approach comprise a synthetically manufactured replica of the bone marrow spaces as osteoconductive ladder, whereas the bead is defined as bone-forming element. As a result, materials are available with high strength if the ceramic is solid or highly porous and possesses a micro-structure. The injection moulding process allows for the combination of high strength of the material with high porosity. Based on the strong capillary forces, micro-chambered beads fulfil most expectations for primary bone formation in cancellous bone defects, including drug delivery, mechanical strengthening if necessary, and stable implantation in situ by coagulation of the blood and bone marrow suctioned in. Copyright © 2011 Elsevier Ltd. All rights reserved.

Influence of muscle strength, physical activity and weight on bone mass in a population-based sample of 1004 elderly women.

PubMed

Gerdhem, P; Ringsberg, K A M; Akesson, K; Obrant, K J

2003-09-01

High physical activity level has been associated with high bone mass and low fracture risk and is therefore recommended to reduce fractures in old age. The aim of this study was to estimate the effect of potentially modifiable variables, such as physical activity, muscle strength, muscle mass and weight, on bone mass in elderly women. The influence of isometric thigh muscle strength, self-estimated activity level, body composition and weight on bone mineral density (dual energy X-ray absorptiometry; DXA) in total body, hip and spine was investigated. Subjects were 1004 women, all 75 years old, taking part in the Malmö Osteoporosis Prospective Risk Assessment (OPRA) study. Physical activity and muscle strength accounted for 1-6% of the variability in bone mass, whereas weight, and its closely associated variables lean mass and fat mass, to a much greater extent explained the bone mass variability. We found current body weight to be the variable with the most substantial influence on the total variability in bone mass (15-32% depending on skeletal site) in a forward stepwise regression model. Our findings suggest that in elderly women, the major fracture-preventive effect of physical activity is unlikely to be mediated through increased bone mass. Retaining or even increasing body weight is likely to be beneficial to the skeleton, but an excess body weight increase may have negative effects on health. Nevertheless, training in elderly women may have advantages by improving balance, co-ordination and mobility and therefore decreasing the risk of fractures.

Evaluation of Bone Strength During Aflatoxicosis and Ochratoxicosis †

PubMed Central

Huff, William E.; Doerr, John A.; Hamilton, Pat B.; Hamann, Donald D.; Peterson, Robert E.; Ciegler, Alex

1980-01-01

Young chickens were fed graded levels of aflatoxin (0, 0.625, 1.25, 2.5, 5.0, and 10.0 μg/g of diet) or ochratoxin (0, 0.5, 1.0, 2.0, 4.0, and 8.0 μg/g of diet), and the breaking strength, displacement before failure, and diameter of their tibias were determined. Breaking strength was decreased at growth inhibitory levels of aflatoxin (2.5 μg/g) and ochratoxin (2 μg/g), whereas a reduction in diameter required higher levels (5.0 and 4.0 μg/g, respectively). Bones from birds with ochratoxicosis selected to have diameters equal to control bones had lower breaking strength. In an attempt to negate mathematically the effect of decreased diameter and bias in any selection process, stress at time of failure of the bones was calculated and found to be decreased by feeding aflatoxin but not ochratoxin. Total displacement of bones before breaking was increased significantly (P < 0.05) by both toxins at the highest levels administered, but this increase was primarily the result of an increase in displacement from the start of failure to complete failure. Increased displacement associated with both toxicoses was equal in bones selected to be of equal diameter or in bones from the same treatment but of different diameters. However, calculation of modulus of elasticity which is corrected for diameter revealed aflatoxin had no effect whereas ochratoxin tripled the effect. These data indicate that the material properties of bones can be altered during mycotoxicoses and suggest yet another way in which mycotoxins are detrimental to animal health. PMID:7406489

Sex Differences in Tibial Bone Strength

NASA Technical Reports Server (NTRS)

Arnaud, Sara B.; Hutchinson, T. M.; Torikoshi, S.; Hutchinson, K. J.; Hargens, Alan R.; Steele, C. R.

1995-01-01

We have used an instrument (MRTA or Mechanical Response Tissue Analyzer) that measures bending stiffness (EI) non-Invasively to evaluate the strength of the tibia, a long bone in the weightbearing skeleton highly vulnerable to mineral loss during space flight. In healthy men, we found asymmetry in EI consistent with the bone's support function (L greater than R). In this study, we analyzed EI in women and compared the results to those in men.

Contributions of Severe Burn and Disuse to Bone Structure and Strength in Rats

PubMed Central

Baer, L.A.; Wu, X.; Tou, J. C.; Johnson, E.; Wolf, S.E.; Wade, C.E.

2012-01-01

Burn and disuse results in metabolic and bone changes associated with substantial and sustained bone loss. Such loss can lead to an increased fracture incidence and osteopenia. We studied the independent effects of burn and disuse on bone morphology, composition and strength, and microstructure of the bone alterations 14 days after injury. Sprague-Dawley rats were randomized into four groups: Sham/Ambulatory (SA), Burn/Ambulatory (BA), Sham/Hindlimb Unloaded (SH) and Burn/Hindlimb Unloaded (BH). Burn groups received a 40% total body surface area full-thickness scald burn. Disuse by hindlimb unloading was initiated immediately following injury. Bone turnover was determined in plasma and urine. Femur biomechanical parameters were measured by three-point bending tests and bone microarchitecture was determined by microcomputed tomography (uCT). On day 14, a significant reduction in body mass was observed as a result of burn, disuse and a combination of both. In terms of bone health, disuse alone and in combination affected femur weight, length and bone mineral content. Bending failure energy, an index of femur strength, was significantly reduced in all groups and maximum bending stress was lower when burn and disuse were combined. Osteocalcin was reduced in BA compared to the other groups, indicating influence of burn. The reductions observed in femur weight, BMC, biomechanical parameters and indices of bone formation are primarily responses to the combination of burn and disuse. These results offer insight into bone degradation following severe injury and disuse. PMID:23142361

The effect of feeding different sugar-sweetened beverages to growing female Sprague-Dawley rats on bone mass and strength.

PubMed

Tsanzi, Embedzayi; Light, Heather R; Tou, Janet C

2008-05-01

Consumption of sugar beverages has increased among adolescents. Additionally, the replacement of sucrose with high fructose corn syrup (HFCS) as the predominant sweetener has resulted in higher fructose intake. Few studies have investigated the effect of drinking different sugar-sweetened beverages on bone, despite suggestions that sugar consumption negatively impacts mineral balance. The objective of this study was to determine the effect of drinking different sugar-sweetened beverages on bone mass and strength. Adolescent (age 35d) female Sprague-Dawley rats were randomly assigned (n=8-9/group) to consume deionized distilled water (ddH2O, control) or ddH2O containing 13% w/v glucose, sucrose, fructose or high fructose corn syrup (HFCS-55) for 8weeks. Tibia and femur measurements included bone morphometry, bone turnover markers, determination of bone mineral density (BMD) and bone mineral content (BMC) by dual energy X-ray absorptiometry (DXA) and bone strength by three-point bending test. The effect of sugar-sweetened beverage consumption on mineral balance, urinary and fecal calcium (Ca) and phosphorus (P) was measured by inductively coupled plasma optical emission spectrometry. The results showed no difference in the bone mass or strength of rats drinking the glucose-sweetened beverage despite their having the lowest food intake, but the highest beverage and caloric consumption. Only in comparisons among the rats provided sugar-sweetened beverage were femur and tibia BMD lower in rats drinking the glucose-sweetened beverage. Differences in bone and mineral measurements appeared most pronounced between rats drinking glucose versus fructose-sweetened beverages. Rats provided the glucose-sweetened beverage had reduced femur and tibia total P, reduced P and Ca intake and increased urinary Ca excretion compared to the rats provided the fructose-sweetened beverage. The results suggested that glucose rather than fructose exerted more deleterious effects on mineral balance and bone.

Is a school-based physical activity intervention effective for increasing tibial bone strength in boys and girls?

PubMed

Macdonald, Heather M; Kontulainen, Saija A; Khan, Karim M; McKay, Heather A

2007-03-01

This 16-month randomized, controlled school-based study compared change in tibial bone strength between 281 boys and girls participating in a daily program of physical activity (Action Schools! BC) and 129 same-sex controls. The simple, pragmatic intervention increased distal tibia bone strength in prepubertal boys; it had no effect in early pubertal boys or pre or early pubertal girls. Numerous school-based exercise interventions have proven effective for enhancing BMC, but none have used pQCT to evaluate the effects of increased loading on bone strength during growth. Thus, our aim was to determine whether a daily program of physical activity, Action Schools! BC (AS! BC) would improve tibial bone strength in boys and girls who were pre- (Tanner stage 1) or early pubertal (Tanner stage 2 or 3) at baseline. Ten schools were randomized to intervention (INT, 7 schools) or control (CON, 3 schools). The bone-loading component of AS! BC included a daily jumping program (Bounce at the Bell) plus 15 minutes/day of classroom physical activity in addition to regular physical education. We used pQCT to compare 16-month change in bone strength index (BSI, mg2/mm4) at the distal tibia (8% site) and polar strength strain index (SSIp, mm3) at the tibial midshaft (50% site) in 281 boys and girls participating in AS! BC and 129 same-sex controls. We used a linear mixed effects model to analyze our data. Children were 10.2+/-0.6 years at baseline. Intervention boys tended to have a greater increase in BSI (+774.6 mg2/mm4; 95% CI: 672.7, 876.4) than CON boys (+650.9 mg2/mm4; 95% CI: 496.4, 805.4), but the difference was only significant in prepubertal boys (p=0.03 for group x maturity interaction). Intervention boys also tended to have a greater increase in SSIp (+198.6 mm3; 95% CI: 182.9, 214.3) than CON boys (+177.1 mm3; 95% CI: 153.5, 200.7). Change in BSI and SSIp was similar between CON and INT girls. Our findings suggest that a simple, pragmatic program of daily activity enhances bone strength at the distal tibia in prepubertal boys. The precise exercise prescription needed to elicit a similar response in more mature boys or in girls might be best addressed in a dose-response trial.

Mouse shoulder morphology responds to locomotor activity and the kinematic differences of climbing and running.

PubMed

Green, David J; Richmond, Brian G; Miran, Sara L

2012-12-01

Mechanical loads play a significant role in determining long bone shape and strength, but less work has explored how these loads influence flat bones like the scapula, which has been shown to vary with locomotor preference among primate taxa. Here, we tested the effects of voluntary running and climbing exercise in mice to examine how the mechanical loads borne from different locomotor patterns influence shoulder morphological development. Ninety-nine female wild-type mice were distributed equally among sedentary control, activity-wheel running, and vertical climbing experimental conditions. Running mice had the lowest body masses, larger intrinsic shoulder muscles, and the most pronounced differences in scapular size and shape relative to the other groups. Climbing mouse scapular morphology also differed significantly from the control individuals, but these differences were not as marked as those between the running and control mice. This might be attributable in part to greater levels of activity in the wheel-runners relative to the climbers. Additionally, climbing mice held their bodies closer to the substrate and maintained more flexed limbs and posterior hand positions compared with the kinematics of running. As a result, climbers differed significantly from both the running and control mice in developing a relatively broader infraspinous region, which is likely related to preferential recruitment of the infraspinatus and teres minor muscles to maintain flexed shoulder postures. The results of this study demonstrate that variation in activity level and type of locomotor regime over a significant portion of the life history influences muscle and bone development in the shoulder. Copyright © 2012 Wiley Periodicals, Inc.

Influence of Nano-HA Coated Bone Collagen to Acrylic (Polymethylmethacrylate) Bone Cement on Mechanical Properties and Bioactivity

PubMed Central

Li, Tao; Weng, Xisheng; Bian, Yanyan; Zhou, Lei; Cui, Fuzhai; Qiu, Zhiye

2015-01-01

Objective This research investigated the mechanical properties and bioactivity of polymethylmethacrylate (PMMA) bone cement after addition of the nano-hydroxyapatite(HA) coated bone collagen (mineralized collagen, MC). Materials & Methods The MC in different proportions were added to the PMMA bone cement to detect the compressive strength, compression modulus, coagulation properties and biosafety. The MC-PMMA was embedded into rabbits and co-cultured with MG 63 cells to exam bone tissue compatibility and gene expression of osteogenesis. Results 15.0%(wt) impregnated MC-PMMA significantly lowered compressive modulus while little affected compressive strength and solidification. MC-PMMA bone cement was biologically safe and indicated excellent bone tissue compatibility. The bone-cement interface crosslinking was significantly higher in MC-PMMA than control after 6 months implantation in the femur of rabbits. The genes of osteogenesis exhibited significantly higher expression level in MC-PMMA. Conclusions MC-PMMA presented perfect mechanical properties, good biosafety and excellent biocompatibility with bone tissues, which has profoundly clinical values. PMID:26039750

Influence of Nano-HA Coated Bone Collagen to Acrylic (Polymethylmethacrylate) Bone Cement on Mechanical Properties and Bioactivity.

PubMed

Li, Tao; Weng, Xisheng; Bian, Yanyan; Zhou, Lei; Cui, Fuzhai; Qiu, Zhiye

2015-01-01

This research investigated the mechanical properties and bioactivity of polymethylmethacrylate (PMMA) bone cement after addition of the nano-hydroxyapatite(HA) coated bone collagen (mineralized collagen, MC). The MC in different proportions were added to the PMMA bone cement to detect the compressive strength, compression modulus, coagulation properties and biosafety. The MC-PMMA was embedded into rabbits and co-cultured with MG 63 cells to exam bone tissue compatibility and gene expression of osteogenesis. 15.0%(wt) impregnated MC-PMMA significantly lowered compressive modulus while little affected compressive strength and solidification. MC-PMMA bone cement was biologically safe and indicated excellent bone tissue compatibility. The bone-cement interface crosslinking was significantly higher in MC-PMMA than control after 6 months implantation in the femur of rabbits. The genes of osteogenesis exhibited significantly higher expression level in MC-PMMA. MC-PMMA presented perfect mechanical properties, good biosafety and excellent biocompatibility with bone tissues, which has profoundly clinical values.

Positive effects of bisphosphonates on bone and muscle in a mouse model of Duchenne muscular dystrophy.

PubMed

Yoon, Sung-Hee; Sugamori, Kim S; Grynpas, Marc D; Mitchell, Jane

2016-01-01

Patients with Duchenne muscular dystrophy are at increased risk of decreased bone mineral density and bone fracture as a result of inactivity. To determine if antiresorptive bisphosphonates could improve bone quality and their effects on muscle we studied the Mdx mouse, treated with pamidronate during peak bone growth at 5 and 6 weeks of age, and examined the outcome at 13 weeks of age. Pamidronate increased cortical bone architecture and strength in femurs with increased resistance to fracture. While overall long bone growth was not affected by pamidronate, there was significant inhibition of remodeling in metaphyseal trabecular bone with evidence of residual calcified cartilage. Pamidronate treatment had positive effects on skeletal muscle in the Mdx mice with decreased serum and muscle creatine kinase and evidence of improved muscle histology and grip strength. Copyright © 2015 Elsevier B.V. All rights reserved.

In healthy elderly postmenopausal women variations in BMD and BMC at various skeletal sites are associated with differences in weight and lean body mass rather than by variations in habitual physical activity, strength or VO2max.

PubMed

Schöffl, I; Kemmler, W; Kladny, B; Vonstengel, S; Kalender, W A; Engelke, K

2008-01-01

The objective of this study was an integrated cross-sectional investigation for answering the question whether differences in bone mineral density in elderly postmenopausal women are associated with differences in habitual physical activity and unspecific exercise levels. Two hundred and ninety nine elderly women (69-/+3 years), without diseases or medication affecting bone metabolism were investigated. The influence of weight, body composition and physical activity on BMD was measured at multiple sites using different techniques (DXA, QCT, and QUS). Physical activity and exercise level were assessed by questionnaire, maximum strength of the legs and aerobic capacity. Variations in physical activity or habitual exercise had no effect on bone. The only significant univariate relation between strength/VO(2)max and BMD/BMC that remained after adjusting for confounding variables was between arm BMD (DXA) and hand-grip strength. The most important variable for explaining BMD was weight and for cortical BMC of the femur (QCT) lean body mass. Weight and lean body mass emerge as predominant predictors of BMD in normal elderly women, whereas the isolated effect of habitual physical activity, unspecific exercise participation, and muscle strength on bone parameters is negligible. Thus, an increase in the amount of habitual physical activity will probably have no beneficial impact on bone.

Chronic administration of anticonvulsants but not antidepressants impairs bone strength: clinical implications.

PubMed

Gold, P W; Pavlatou, M G; Michelson, D; Mouro, C M; Kling, M A; Wong, M-L; Licinio, J; Goldstein, S A

2015-06-02

Major depression and bipolar disorder are associated with decreased bone mineral density (BMD). Antidepressants such as imipramine (IMIP) and specific serotonin reuptake inhibitors (SSRIs) have been implicated in reduced BMD and/or fracture in older depressed patients. Moreover, anticonvulsants such as valproate (VAL) and carbamazepine (CBZ) are also known to increase fracture rates. Although BMD is a predictor of susceptibility to fracture, bone strength is a more sensitive predictor. We measured mechanical and geometrical properties of bone in 68 male Sprague Dawley rats on IMIP, fluoxetine (FLX), VAL, CBZ, CBZ vehicle and saline (SAL), given intraperitoneally daily for 8 weeks. Distinct regions were tested to failure by four-point bending, whereas load displacement was used to determine stiffness. The left femurs were scanned in a MicroCT system to calculate mid-diaphyseal moments of inertia. None of these parameters were affected by antidepressants. However, VAL resulted in a significant decrease in stiffness and a reduction in yield, and CBZ induced a decrease in stiffness. Only CBZ induced alterations in mechanical properties that were accompanied by significant geometrical changes. These data reveal that chronic antidepressant treatment does not reduce bone strength, in contrast to chronic anticonvulsant treatment. Thus, decreased BMD and increased fracture rates in older patients on antidepressants are more likely to represent factors intrinsic to depression that weaken bone rather than antidepressants per se. Patients with affective illness on anticonvulsants may be at particularly high risk for fracture, especially as they grow older, as bone strength falls progressively with age.

Systematic strength training as a model of therapeutic intervention. A controlled trial in postmenopausal women with osteopenia.

PubMed

Hartard, M; Haber, P; Ilieva, D; Preisinger, E; Seidl, G; Huber, J

1996-01-01

Physical exercise is often recommended as a therapeutic tool to combat pre- and postmenopausal loss of bone density. However, the relationship between training dosage (intensity, duration, frequency) and the effect on bone density still is undergoing discussion. Furthermore, the exercise quantification programs are often described so inadequately that they are neither quantitatively nor qualitatively reproducible. The aim of this investigation was to determine whether a clearly defined training of muscle strength, under defined safety aspects, performed only twice weekly, can counteract bone density loss in women with postmenopausal osteopenia. Data from 16 women in the training group (age, 63.6 +/- 6.2 yr) and 15 women in the control group (age, 67.4 +/-9.7 yr), of comparable height and weight, were evaluated. Strength training was performed for 6 mo as continually adapted strength training, providing an intensity of about 70% of each test person's one repetition maximum. Bone mineral density of lumbar vertebrae 2 to 4 and the femoral neck was measured by dual-energy x-ray absorptiometry. Maximum performance in watts and parameters of hemodynamics were controlled with a bicycle ergometer test to maximal effort. In addition, metabolic data were assessed. In the lumbar spine and femoral neck, the training group showed no significant changes, whereas the control group demonstrated a significant loss of bone mineral density, especially in the femoral neck (P<0.05). The strength increase was highly significant in all exercised muscle groups, rising to about 70% above the pretraining status (P<0.001). Heart rate and blood pressure data indicated a slight economization, metabolism was not significantly influenced. Based on these findings, we conclude that continually adapted strength training is an effective, safe, reproducible, and adaptable method of therapeutic strength training, following only two exercise sessions per week.

Effects of suspension-induced osteopenia on the mechanical behaviour of mouse long bones

NASA Technical Reports Server (NTRS)

Simske, S. J.; Greenberg, A. R.; Luttges, M. W.; Spooner, B. S. (Principal Investigator)

1991-01-01

Whereas most studies of tail-suspension induced osteopenia have utilized rat femora, the present study investigated the effects of a 14 day tail-suspension on the mechanical behaviour of mice femora, tibiae and humeri. Force-deflection properties were obtained via three-point bending for long bones from suspended and control mice. Whole bone behaviour was characterized by converting the force-deflection values to stiffness, strength, ductility and energy parameters which were not normalized for specimen geometry. The effects of a systematic variation in the deflection rate over the range 0.1-10 mm min-1 were also evaluated. Statistical analysis indicated that the primary effect of the tail-suspension period was lowered bone mass which was manifested mechanically through lower values of the bone strength parameters. These effects were similar in the bones of both the fore and hind limbs. The results also demonstrated that the stiffness, ductility and energy characteristics were much less influenced by the tail-suspension. Whereas a significant dependence of the bone strength values upon deflection rate was observed for the femora and humeri, the other mechanical parameters were less sensitive. Based upon the nature of the physical and mechanical changes observed in the long bones following tail-suspension, the mouse appears to be a suitable animal model for the study of osteopenia.

The Effects of Combined Treatment with Naringin and Treadmill Exercise on Osteoporosis in Ovariectomized Rats

PubMed Central

SUN, Xiaolei; Fengbo, LI; Xinlong, MA; Jianxiong, MA; ZHAO, Bin; ZHANG, Yang; Yanjun, LI; Jianwei, LV; MENG, Xinmin

2015-01-01

Osteoporosis is a disease characterized by low bone mass and progressive destruction of bone microstructure, resulting in increased the risk of fracture. Previous studies have demonstrated the effect of naringin (NG) or treadmill exercise (EX) on osteoporosis, however, reports about effects of NG plus EX on osteoporosis are limited. This study was designed to investigate the impact of combined treatment with naringin and treadmill exercise on osteoporosis in ovariectomized (OVX) rats. Three months after bilateral ovariectomy, Seventy-five rats were randomly assigned to the following treatment groups: OVX, sham-operated (SHAM), NG, EX, or NG plus EX treatment. Treatments were administered for 60 days. Bone metabolism, bone mineral density, trabecular bone parameters, immunohistochemistry, and the bone strength were evaluated. Compared to the OVX groups, all treatments increased bone volume (BV/TV), trabecula number (Tb.N), trabecula thickness (Tb.Th), bone mineral density (BMD), and mechanical strength. NG + EX showed the strongest effects on BV/TV, Tb.Th, and biomechanical strength. Additionally, decreased C-terminal telopeptides of type I collagen (CTX-1) and enhanced osteocalcin (OCN) expression were observed in the NG + EX group. The present study demonstrates that the NG + EX may have a therapeutic advantage over each monotherapy for the treatment of osteoporosis. PMID:26260240

Biocompatibility and Biocorrosion of Hydroxyapatite-Coated Magnesium Plate: Animal Experiment.

PubMed

Lim, Ho-Kyung; Byun, Soo-Hwan; Woo, Jae-Man; Kim, Sae-Mi; Lee, Sung-Mi; Kim, Bong-Ju; Kim, Hyoun-Ee; Lee, Jung-Woo; Kim, Soung-Min; Lee, Jong-Ho

2017-09-30

Magnesium (Mg) has the advantage of being resorbed in vivo, but its resorption rate is difficult to control. With uncontrolled resorption, Magnesium as a bone fixation material has minimal clinical value. During resorption not only is the strength rapidly weakened, but rapid formation of metabolite also occurs. In order to overcome these disadvantages, hydroxyapatite (HA) surface coating of pure magnesium plate was attempted in this study. Magnesium plates were inserted above the frontal bone of Sprague-Dawley rats in both the control group (Bare-Mg group) and the experimental group (HA-Mg group). The presence of inflammation, infection, hydrogen gas formation, wound dehiscence, and/or plate exposure was observed, blood tests were performed, and the resorption rate and tensile strength of the retrieved metal plates were measured. The HA-Mg group showed no gas formation or plate exposure until week 12. However, the Bare-Mg group showed consistent gas formation and plate exposure beginning in week 2. WBC (White Blood Cell), BUN (Blood Urea Nitrogen), Creatinine, and serum magnesium concentration levels were within normal range in both groups. AST (Aspartate Aminotransferase) and ALT (Alanine Aminotransferase) values, however, were above normal range in some animals of both groups. The HA-Mg group showed statistically significant advantage in resistance to degradation compared to the Bare-Mg group in weeks 2, 4, 6, 8, and 12. Degradation of HA-Mg plates proceeded after week 12. Coating magnesium plates with hydroxyapatite may be a viable method to maintain their strength long enough to allow bony healing and to control the resorption rate during the initial period.

Doped tricalcium phosphate bone tissue engineering scaffolds using sucrose as template and microwave sintering: enhancement of mechanical and biological properties.

PubMed

Ke, Dongxu; Bose, Susmita

2017-09-01

β-tricalcium phosphate (β-TCP) is a widely used biocompatible ceramic in orthopedic and dental applications. However, its osteoinductivity and mechanical properties still require improvements. In this study, porous β-TCP and MgO/ZnO-TCP scaffolds were prepared by the thermal decomposition of sucrose. Crack-free cylindrical scaffolds could only be prepared with the addition of MgO and ZnO due to their stabilization effects. Porous MgO/ZnO-TCP scaffolds with a density of 61.39±0.66%, an estimated pore size of 200μm and a compressive strength of 24.96±3.07MPa were prepared by using 25wt% sucrose after conventional sintering at 1250°C. Microwave sintering further increased the compressive strength to 37.94±6.70MPa, but it decreased the open interconnected porosity to 8.74±1.38%. In addition, the incorporation of polycaprolactone (PCL) increased 22.36±3.22% of toughness while maintaining its compressive strength at 25.45±2.21MPa. Human osteoblast cell line was seeded on scaffolds to evaluate the effects of MgO/ZnO and PCL on the biological property of β-TCP in vitro. Both MgO/ZnO and PCL improved osteoinductivity of β-TCP. PCL also decreased osteoblastic apoptosis due to its particular surface chemistry. This novel porous MgO/ZnO-TCP scaffold with PCL shows improved mechanical and biological properties, which has great potential in bone tissue engineering applications. Copyright © 2017. Published by Elsevier B.V.

Biocompatibility and Biocorrosion of Hydroxyapatite-Coated Magnesium Plate: Animal Experiment

PubMed Central

Woo, Jae-Man; Kim, Sae-Mi; Lee, Sung-Mi; Kim, Hyoun-Ee; Lee, Jung-Woo; Lee, Jong-Ho

2017-01-01

Magnesium (Mg) has the advantage of being resorbed in vivo, but its resorption rate is difficult to control. With uncontrolled resorption, Magnesium as a bone fixation material has minimal clinical value. During resorption not only is the strength rapidly weakened, but rapid formation of metabolite also occurs. In order to overcome these disadvantages, hydroxyapatite (HA) surface coating of pure magnesium plate was attempted in this study. Magnesium plates were inserted above the frontal bone of Sprague-Dawley rats in both the control group (Bare-Mg group) and the experimental group (HA-Mg group). The presence of inflammation, infection, hydrogen gas formation, wound dehiscence, and/or plate exposure was observed, blood tests were performed, and the resorption rate and tensile strength of the retrieved metal plates were measured. The HA-Mg group showed no gas formation or plate exposure until week 12. However, the Bare-Mg group showed consistent gas formation and plate exposure beginning in week 2. WBC (White Blood Cell), BUN (Blood Urea Nitrogen), Creatinine, and serum magnesium concentration levels were within normal range in both groups. AST (Aspartate Aminotransferase) and ALT (Alanine Aminotransferase) values, however, were above normal range in some animals of both groups. The HA-Mg group showed statistically significant advantage in resistance to degradation compared to the Bare-Mg group in weeks 2, 4, 6, 8, and 12. Degradation of HA-Mg plates proceeded after week 12. Coating magnesium plates with hydroxyapatite may be a viable method to maintain their strength long enough to allow bony healing and to control the resorption rate during the initial period. PMID:28973984

Mechanical Strength of the Proximal Femur After Arthroscopic Osteochondroplasty for Femoroacetabular Impingement: Finite Element Analysis and 3-Dimensional Image Analysis.

PubMed

Oba, Masatoshi; Kobayashi, Naomi; Inaba, Yutaka; Choe, Hyonmin; Ike, Hiroyuki; Kubota, So; Saito, Tomoyuki

2018-06-21

To examine the influence of femoral neck resection on the mechanical strength of the proximal femur in actual surgery. Eighteen subjects who received arthroscopic cam resection for cam-type femoroacetabular impingement (FAI) were included. Finite element analyses (FEAs) were performed to calculate changes in simulative fracture load between pre- and postoperative femur models. The finite element femur models were constructed from computed tomographic images; thus, the models represented the shape of the original femur, including the bone resection site. Three-dimensional image analysis of the bone resection site was performed to identify morphometric factors that affect strength in the postoperative femur model. Four oblique sagittal planes running perpendicular to the femoral neck axis were used as reference planes to measure the bone resection site. At the transcervical reference plane, both the bone resection depth and the cross-sectional area at the resection site correlated strongly with postoperative changes in the simulated fracture load (R 2  = 0.6, P = .0001). However, only resection depth was significantly correlated with the simulated fracture load at the reference plane for the head-neck junction. The resected bone volume did not correlate with the postoperative changes in the simulated fracture load. The results of our FEA suggest that the bone resection depth measured at the head-neck junction and transcervical reference plane correlates with fracture risk after osteochondroplasty. By contrast, bone resection at more proximal areas did not have a significant effect on the postoperative femur model strength in our FEA. The total volume of resected bone was also not significantly correlated with postoperative changes in femur model strength. This biomechanical study using FEA suggest that there is a risk of femoral neck fracture after arthroscopic cam resection, particularly when the resected lesion is located distally. Copyright © 2018 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Improving Bone-Health Monitoring in Astronauts: Recommended Use of Quantitative Computed Tomography [QCT] for Clinical and Operational Decisions by NASA

NASA Technical Reports Server (NTRS)

Sibonga, J. D.; Truszkowski, P.

2010-01-01

DXA measurement of areal bone mineral density [aBMD,g/cm2] is required by NASA for assessing skeletal integrity in astronauts. Due to the abundance of population-based data that correlate hip and spine BMDs to fragility fractures, BMD is widely applied as a predictor of fractures in the general aging population. In contrast, QCT is primarily a research technology that measures three-dimensional , volumetric BMD (vBMD,mg/cm3) of bone and is therefore capable of differentiating between cortical and trabecular components. Additionally, when combined with Finite Element Modeling [FEM], a computational tool, QCT data can be used to estimate the whole bone strength of the hip [FE strength] for a specific load vector. A recent report demonstrated that aBMD failed to correlate with incurred changes in FE strength (for fall and stance loading) by astronauts over typical 180-day ISS (International Space Station) missions. While there are no current guidelines for using QCT data in clinical practice, QCT increases the understanding of how bone structure and mineral content are affected by spaceflight and recovery on Earth. In order to understand/promote/consider the use of QCT, NASA convened a panel of clinicians specializing in osteoporosis. After reviewing the available, albeit limited, medical and research information from long-duration astronauts (e.g., data from DXA, QCT, FEM, biochemistry analyses, medical records and in-flight exercise performance) the panelists were charged with recommending how current and future research data and analyses could inform clinical and operational decisions. The Panel recommended that clinical bone tests on astronauts should include QCT (hip and lumbar spine) for occupational risk surveillance and for the estimation of whole hip bone strength as derived by FEM. FE strength will provide an improved index that NASA could use to select astronauts of optimal bone health for extended duration missions, for repeat missions or for specific mission operations.

An approximate model for cancellous bone screw fixation.

PubMed

Brown, C J; Sinclair, R A; Day, A; Hess, B; Procter, P

2013-04-01

This paper presents a finite element (FE) model to identify parameters that affect the performance of an improved cancellous bone screw fixation technique, and hence potentially improve fracture treatment. In cancellous bone of low apparent density, it can be difficult to achieve adequate screw fixation and hence provide stable fracture fixation that enables bone healing. Data from predictive FE models indicate that cements can have a significant potential to improve screw holding power in cancellous bone. These FE models are used to demonstrate the key parameters that determine pull-out strength in a variety of screw, bone and cement set-ups, and to compare the effectiveness of different configurations. The paper concludes that significant advantages, up to an order of magnitude, in screw pull-out strength in cancellous bone might be gained by the appropriate use of a currently approved calcium phosphate cement.

Sclerostin Blockade and Zoledronic Acid Improve Bone Mass and Strength in Male Mice With Exogenous Hyperthyroidism.

PubMed

Tsourdi, Elena; Lademann, Franziska; Ominsky, Michael S; Rijntjes, Eddy; Köhrle, Josef; Misof, Barbara M; Roschger, Paul; Klaushofer, Klaus; Hofbauer, Lorenz C; Rauner, Martina

2017-11-01

Hyperthyroidism in mice is associated with low bone mass, high bone turnover, and high concentrations of sclerostin, a potent Wnt inhibitor. Here, we explored the effects of either increasing bone formation with sclerostin antibodies (Scl-Ab) or reducing bone turnover with bisphosphonates on bone mass and strength in hyperthyroid mice. Twelve-week-old C57BL/6 male mice were rendered hyperthyroid using l-thyroxine (T4; 1.2 µg/mL added to the drinking water) and treated with 20 mg/kg Scl-Ab twice weekly or 100 µg/kg zoledronic acid (ZOL) once weekly or phosphate-buffered saline for 4 weeks. Hyperthyroid mice displayed a lower trabecular bone volume at the spine (-42%, P < 0.05) and the distal femur (-55%, P < 0.05) compared with euthyroid controls. Scl-Ab and ZOL treatment of hyperthyroid mice increased trabecular bone volume at the spine by threefold and twofold, respectively. Serum bone formation and resorption markers were increased in hyperthyroid mice and suppressed by treatment with ZOL but not Scl-Ab. Trabecular bone stiffness at the lumbar vertebra was 63% lower in hyperthyroid mice (P < 0.05) and was increased fourfold by Sci-Ab (P < 0.001) and threefold by ZOL treatment (P < 0.01). Bone strength based on ultimate load, which was 10% lower in hyperthyroidism, was increased by Scl-Ab by 71% and ZOL by 22% (both P < 0.001). Increased proportion of low mineralized bone seen in hyperthyroid mice was restored by treatment with Scl-Ab and ZOL. Thus, bone-forming and antiresorptive drugs prevent bone loss in hyperthyroid mice via different mechanisms. Copyright © 2017 Endocrine Society.

Intraoperative mechanical bone strength determination in tibiotalocalcaneal fusion: a biomechanical investigation.

PubMed

Klos, Kajetan; Windolf, Markus; Schwieger, Karsten; Kuhn, Philipp; Hänni, Markus; Gueorguiev, Boyko; Hofmann, Gunther O; Mückley, Thomas

2009-12-01

Bone strength is currently measured with indirect techniques. We investigated the use of an intraoperative mechanical measurement for local bone strength determination and prediction of intramedullary-nail fusion failure. We investigated whether intraoperative local bone strength determination may be useful to the surgeon in predicting intramedullary nail hindfoot fusion performance. In seven human specimens, bone mineral density (BMD) was determined with qCT. A device (DensiProbe) specially devised for nailed tibiotalocalcaneal arthrodesis (TTCA) was inserted at the intended calcaneal screw sites of an intramedullary nail, and the cancellous break-away torque was measured. The constructs were then cyclically loaded to failure in dorsiflexion-plantarfexion. The BMD range was wide (42.8 to 185.9 mg HA/cm(3)). The proximal-screw site peak torque was 0.47 to 1.61 Nm; distal-screw site peak torque was 0.24 to 1.06 Nm. The number of cycles to failure correlated with peak torque both proximally (p = 0.021; r(2) = 0.69) and distally (p = 0.001; r(2) = 0.92). Proximally, peak torque did not correlate with BMD (p = 0.060; r(2) = 0.54); distally, it correlated significantly (p = 0.003; r(2) = 0.86). DensiProbe measurements can be used in the hindfoot to assess bone strength. In this study, specimens that failed early could be identified. However, in clinical practice fusion failure is multifactorial in origin, and failure prediction cannot be based upon peak torque measurements alone. The technique described here may be of use to give an intraoperative decision aid to predict intramedullary nail hindfoot fusion performance.

Pullout strength of cement-augmented and wide-suture transosseous fixation in the greater tuberosity.

PubMed

Shi, Brendan Y; Diaz, Miguel; Belkoff, Stephen M; Srikumaran, Uma

2017-12-01

Obtaining strong fixation in low-density bone is increasingly critical in surgical repair of rotator cuff tears because of the aging population. To evaluate two new methods of improving pullout strength of transosseous rotator cuff repair in low-density bone, we analyzed the effects of 1) using 2-mm suture tape instead of no. 2 suture and 2) augmenting the lateral tunnel with cement. Eleven pairs of osteopenic or osteoporotic cadaveric humeri were identified by dual-energy x-ray absorptiometry. One bone tunnel and one suture were placed in the heads of 22 specimens. Five randomly selected pairs were repaired with no. 2 suture; the other six pairs were repaired with 2-mm suture tape. One side of each pair received lateral tunnel cement augmentation. Specimens were tested to suture pullout. Data were fitted to multivariate models that accounted for bone mineral density and other specimen characteristics. Two specimens were excluded because of knot-slipping during testing. Use of suture tape versus no. 2 suture conferred a 75-N increase (95% CI: 37, 113) in pullout strength (P<0.001). Cement augmentation conferred a 42-N improvement (95% CI: 10, 75; P=0.011). Other significant predictors of pullout strength were age, sex, and bone mineral density. We show two methods of improving the fixation strength of transosseous rotator cuff repairs in low-density bone: using 2-mm suture tape instead of no. 2 suture and augmenting the lateral tunnel with cement. These methods may improve the feasibility of transosseous repairs in an aging patient population. Copyright © 2017 Elsevier Ltd. All rights reserved.

Combination sclerostin antibody and zoledronic acid treatment outperforms either treatment alone in a mouse model of osteogenesis imperfecta.

PubMed

Little, David G; Peacock, Lauren; Mikulec, Kathy; Kneissel, Michaela; Kramer, Ina; Cheng, Tegan L; Schindeler, Aaron; Munns, Craig

2017-08-01

In this study, we examined the therapeutic potential of anti-Sclerostin Antibody (Scl-Ab) and bisphosphonate treatments for the bone fragility disorder Osteogenesis Imperfecta (OI). Mice with the Amish OI mutation (Col1a2 G610C mice) and control wild type littermates (WT) were treated from week 5 to week 9 of life with (1) saline (control), (2) zoledronic acid given 0.025mg/kg s.c. weekly (ZA), (3) Scl-Ab given 50mg/kg IV weekly (Scl-Ab), or (4) a combination of both (Scl-Ab/ZA). Functional outcomes were prioritized and included bone mineral density (BMD), bone microarchitecture, long bone bending strength, and vertebral compression strength. By dual-energy absorptiometry, Scl-Ab treatment alone had no effect on tibial BMD, while ZA and Scl-Ab/ZA significantly enhanced BMD by week 4 (+16% and +27% respectively, P<0.05). Scl-Ab/ZA treatment also led to increases in cortical thickness and tissue mineral density, and restored the tibial 4-point bending strength to that of control WT mice. In the spine, all treatments increased compression strength over controls, but only the combined group reached the strength of WT controls. Scl-Ab showed greater anabolic effects in the trabecular bone than in cortical bone. In summary, the Scl-Ab/ZA intervention was superior to either treatment alone in this OI mouse model, however further studies are required to establish its efficacy in other preclinical and clinical scenarios. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

Effect of long-term impact-loading on mass, size, and estimated strength of humerus and radius of female racquet-sports players: a peripheral quantitative computed tomography study between young and old starters and controls.

PubMed

Kontulainen, Saija; Sievänen, Harri; Kannus, Pekka; Pasanen, Matti; Vuori, Ilkka

2003-02-01

Bone characteristics of the humeral shaft and distal radius were measured from 64 female tennis and squash players and their 27 age-, height-, and weight-matched controls with peripheral quantitative tomography (pQCT) and dual energy X-ray absorptiometry (DXA). The players were divided into two groups according to the starting age of their tennis or squash training (either before or after menarche) to examine the possible differences in the loading-induced changes in bone structure and volumetric density. The following pQCT variables were used: bone mineral content, total cross-sectional area of bone (TotA), cross-sectional area of the marrow cavity (CavA) and that of the cortical bone (CoA), cortical wall thickness (CWT), volumetric density of the cortical bone (CoD) and trabecular bone (TrD), and torsional bone strength index for the shaft (BSIt) and compressional bone strength index for the bone end (BSIc). These bone strength indices were compared with the DXA-derived areal bone mineral density (aBMD) to assess how well the latter represents the effect of mechanical loading on apparent bone strength. At the humeral shaft, the loaded arm's greater bone mineral content (an average 19% side-to-side difference in young starters and 9% in old starters), was caused by an enlarged cortex (CoA; side-to-side differences 20% and 9%, respectively). The loaded humerus seemed to have grown periosteally (the CavA did not differ between the sites), leading to 26% and 11% side-to-side BSIt differences in the young and old starters, respectively. CoD was equal between the arms (-1% difference in both player groups). The side-to-side differences in the young starters' bone mineral content, CoA, TotA, CWT, and BSIt were 8-22% higher than those of the controls and 8-14% higher than those of the old starters. Old starters' bone mineral content, CoA, and BSIt side-to-side differences were 6-7% greater than those in the controls. The DXA-derived side-to-side aBMD difference was 7% greater in young starters compared with that of the old starters and 14% compared with that in controls, whereas the difference between old starters and controls was 6%, in favor of the former. All these between-group differences were statistically significant. At the distal radius, the player groups differed significantly from controls in the side-to-side bone mineral content, TrD, and aBMD differences only: the young starters' bone mineral content difference was 9% greater, TrD and aBMD differences were 5% greater than those in the controls, and the old starters' TrD and aBMD differences were both 7% greater than those in the controls. In summary, in both of the female player groups, the structural adaptation of the humeral shaft to long-term loading seemed to be achieved through periosteal enlargement of the bone cortex, although this adaptation was clearly better in the young starters. Exercise-induced cortical enlargement was not so clear at the distal radius (a trabecular bone site), and the study suggested that at long bone ends, the trabecular density could be a modifiable factor to built a stronger bone structure. Conventional DXA-based aBMD measurement detected the intergroup differences in the exercise-induced bone gains, although, because it measured two dimensions of bone only, it seemed to underestimate the effect of exercise on the apparent bone strength, especially if the playing had been started during the growing years.

Reactive oxygen species on bone mineral density and mechanics in Cu,Zn superoxide dismutase (Sod1) knockout mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smietana, Michael J.; Arruda, Ellen M.; Mechanical Engineering, University of Michigan, 2250 GG Brown, 2350 Hayward, Ann Arbor, MI 48109

Research highlights: {yields} Reactive oxygen species (ROS) are considered to be a factor in the onset of a number of age-associated conditions, including loss of BMD. {yields} Cu,Zn-superoxide dismutase (Sod1) deficient mice have increased ROS, reduced bone mineral density, decreased bending stiffness, and decreased strength compared to WT controls. {yields} Increased ROS caused by the deficiency of Sod1, may be responsible for the changes in BMD and bone mechanics and therefore represent an appropriate model for studying mechanisms of age-associated bone loss. -- Abstract: Reactive oxygen species (ROS) play a role in a number of degenerative conditions including osteoporosis. Micemore » deficient in Cu,Zn-superoxide dismutase (Sod1) (Sod1{sup -/-} mice) have elevated oxidative stress and decreased muscle mass and strength compared to wild-type mice (WT) and appear to have an accelerated muscular aging phenotype. Thus, Sod1{sup -/-} mice may be a good model for evaluating the effects of free radical generation on diseases associated with aging. In this experiment, we tested the hypothesis that the structural integrity of bone as measured by bending stiffness (EI; N/mm{sup 2}) and strength (MPa) is diminished in Sod1{sup -/-} compared to WT mice. Femurs were obtained from male and female WT and Sod1{sup -/-} mice at 8 months of age and three-point bending tests were used to determine bending stiffness and strength. Bones were also analyzed for bone mineral density (BMD; mg/cc) using micro-computed tomography. Femurs were approximately equal in length across all groups, and there were no significant differences in BMD or EI with respect to gender in either genotype. Although male and female mice demonstrated similar properties within each genotype, Sod1{sup -/-} mice exhibited lower BMD and EI of femurs from both males and females compared with gender matched WT mice. Strength of femurs was also lower in Sod1{sup -/-} mice compared to WT as well as between genders. These data indicate that increased oxidative stress, due to the deficiency of Sod1 is associated with decreased bone stiffness and strength and Sod1{sup -/-} mice may represent an appropriate model for studying disease processes in aging bone.« less

Early life vitamin D depletion alters the postnatal response to skeletal loading in growing and mature bone

PubMed Central

Buckley, Harriet; Owen, Robert; Marin, Ana Campos; Lu, Yongtau; Eyles, Darryl; Lacroix, Damien; Reilly, Gwendolen C.; Skerry, Tim M.; Bishop, Nick J.

2018-01-01

There is increasing evidence of persistent effects of early life vitamin D exposure on later skeletal health; linking low levels in early life to smaller bone size in childhood as well as increased fracture risk later in adulthood, independently of later vitamin D status. A major determinant of bone mass acquisition across all ages is mechanical loading. We tested the hypothesis in an animal model system that early life vitamin D depletion results in abrogation of the response to mechanical loading, with consequent reduction in bone size, mass and strength during both childhood and adulthood. A murine model was created in which pregnant dams were either vitamin D deficient or replete, and their offspring moved to a vitamin D replete diet at weaning. Tibias of the offspring were mechanically loaded and bone structure, extrinsic strength and growth measured both during growth and after skeletal maturity. Offspring of vitamin D deplete mice demonstrated lower bone mass in the non loaded limb and reduced bone mass accrual in response to loading in both the growing skeleton and after skeletal maturity. Early life vitamin D depletion led to reduced bone strength and altered bone biomechanical properties. These findings suggest early life vitamin D status may, in part, determine the propensity to osteoporosis and fracture that blights later life in many individuals. PMID:29370213

Massage therapy during early postnatal life promotes greater lean mass and bone growth, mineralization, and strength in juvenile and young adult rats.

PubMed

Chen, H; Miller, S; Shaw, J; Moyer-Mileur, L

2009-01-01

The objects of this study were to investigate the effects of massage therapy during early life on postnatal growth, body composition, and skeletal development in juvenile and young adult rats. Massage therapy was performed for 10 minutes daily from D6 to D10 of postnatal life in rat pups (MT, n=24). Body composition, bone area, mineral content, and bone mineral density were measured by dual energy X-ray absorptiometry (DXA); bone strength and intrinsic stiffness on femur shaft were tested by three-point bending; cortical and cancellous bone histomorphometric measurements were performed at D21 and D60. Results were compared to age- and gender-matched controls (C, n=24). D21 body weight, body length, lean mass, and bone area were significantly greater in the MT cohort. Greater bone mineral content was found in male MT rats; bone strength and intrinsic stiffness were greater in D60 MT groups. At D60 MT treatment promoted bone mineralization by increasing trabecular mineral apposition rate in male and endosteal mineral surface in females, and also improved micro-architecture by greater trabeculae width in males and decreasing trabecular separation in females. In summary, massage therapy during early life elicited immediate and prolonged anabolic effects on postnatal growth, lean mass and skeletal developmental in a gender-specific manner in juvenile and young adult rats.

Did saber-tooth kittens grow up musclebound? A study of postnatal limb bone allometry in felids from the Pleistocene of Rancho La Brea.

PubMed

Long, Katherine; Prothero, Donald; Madan, Meena; Syverson, Valerie J P

2017-01-01

Previous studies have demonstrated that the Pleistocene saber-toothed cat Smilodon fatalis had many forelimb adaptations for increased strength, presumably to grapple with and subdue prey. The Rancho La Brea tar pits yield large samples of juvenile limb bones forming a growth series that allow us to examine how Smilodon kittens grew up. Almost all available juvenile limb bones were measured, and reduced major axis fits were calculated to determine the allometric growth trends. Contrary to expectations based on their robust limbs, Smilodon kittens show the typical pattern of growth found in other large felids (such as the Ice Age lion, Panthera atrox, as well as living tigers, cougars, servals, and wildcats) where the limb grows longer and more slender faster than they grow thick. This adaptation is thought to give felids greater running speed. Smilodon kittens do not grow increasingly more robust with age. Instead, they start out robust and follow the ancestral felid growth pattern, while maintaining their robustness compared to other felids. Apparently, the growth of felid forelimbs is highly canalized and their ontogeny is tightly constrained.

A longitudinal study of bone area, content, density, and strength development at the radius and tibia in children 4-12 years of age exposed to recreational gymnastics.

PubMed

Jackowski, S A; Baxter-Jones, A D G; Gruodyte-Raciene, R; Kontulainen, S A; Erlandson, M C

2015-06-01

This study investigated the long-term relationship between the exposure to childhood recreational gymnastics and bone measures and bone strength parameters at the radius and tibia. It was observed that individuals exposed to recreational gymnastics had significantly greater total bone content and area at the distal radius. No differences were observed at the tibia. This study investigated the relationship between exposure to early childhood recreational gymnastics with bone measures and bone strength development at the radius and tibia. One hundred twenty seven children (59 male, 68 female) involved in either recreational gymnastics (gymnasts) or other recreational sports (non-gymnasts) between 4 and 6 years of age were recruited. Peripheral quantitative computed tomography (pQCT) scans of their distal and shaft sites of the forearm and leg were obtained over 3 years, covering the ages of 4-12 years at study completion. Multilevel random effects models were constructed to assess differences in the development of bone measures and bone strength measures between those exposed and not exposed to gymnastics while controlling for age, limb length, weight, physical activity, muscle area, sex, and hours of training. Once age, limb length, weight, muscle area, physical activity, sex, and hours of training effects were controlled, it was observed that individuals exposed to recreational gymnastics had significantly greater total bone area (18.0 ± 7.5 mm(2)) and total bone content (6.0 ± 3.0 mg/mm) at the distal radius (p < 0.05). This represents an 8-21 % benefit in ToA and 8-15 % benefit to ToC from 4 to 12 years of age. Exposure to recreational gymnastics had no significant effect on bone measures at the radius shaft or at the tibia (p > 0.05). Exposure to early life recreational gymnastics provides skeletal benefits to distal radius bone content and area. Thus, childhood recreational gymnastics exposure may be advantageous to bone development at the wrist.

Relationships among diet, physical activity, and dual plane dual-energy X-ray absorptiometry bone outcomes in pre-pubertalgirls.

PubMed

Ren, Jie; Brann, Lynn S; Bruening, Kay S; Scerpella, Tamara A; Dowthwaite, Jodi N

2017-12-01

In pre-pubertal girls, nutrient intakes and non-aquatic organized activity were evaluated as factors in vertebral body bone mass, structure, and strength. Activity, vitamin B 12 , and dietary fiber predicted bone outcomes most consistently. Exercise and vitamin B 12 appear beneficial, whereas high fiber intake appears to be adverse for vertebral body development. Childhood development sets the baseline for adult fracture risk. Most studies evaluate development using postero-anterior (PA) dual-energy X-ray absorptiometry (DXA) areal bone mineral density, bone mineral content, and bone mineral apparent density. In a prior analysis, we demonstrated that PA DXA reflects posterior element properties, rather than vertebral body fracture sites, such that loading is associated with subtle differences in vertebral body geometry, not 3D density. The current analysis is restricted to pre-pubertal girls, for a focused exploration of key nutrient intakes and physical activity as factors in dual plane indices of vertebral body geometry, density, and strength. This cross-sectional analysis used paired PA and supine lateral (LAT) lumbar spine DXA scans to assess "3D" vertebral body bone mineral apparent density (PALATBMAD), "3D" index of structural strength in axial compression (PALATIBS), and fracture risk index (PALATFRI). Diet data were collected using the Youth/Adolescent Questionnaire (YAQ, 1995); organized physical activity was recorded via calendar-based form. Pearson correlations and backward stepwise multiple linear regression analyzed associations among key nutrients, physical activity, and bone outcomes. After accounting for activity and key covariates, fiber, unsupplemented vitamin B 12 , zinc, carbohydrate, vitamin C, unsupplemented magnesium, and unsupplemented calcium intake explained significant variance for one or more bone outcomes (p < 0.05). After adjustment for influential key nutrients and covariates, activity exposure was associated with postero-anterior (PA) areal bone mineral density, PA bone mineral content, PA width, lateral (LAT) BMC, "3D" bone cross-sectional area (coronal plane), "3D" PALATIBS, and PALATFRI benefits (p < 0.05). Physical activity, fiber intake, and unsupplemented B 12 intake appear to influence vertebral body bone mass, density, geometry, and strength in well-nourished pre-pubertal girls; high fiber intakes may adversely affect childhood vertebral body growth.

Cortical bone deficit and fat infiltration of bone marrow and skeletal muscle in ambulatory children with mild spastic cerebral palsy.

PubMed

Whitney, Daniel G; Singh, Harshvardhan; Miller, Freeman; Barbe, Mary F; Slade, Jill M; Pohlig, Ryan T; Modlesky, Christopher M

2017-01-01

Nonambulatory children with severe cerebral palsy (CP) have underdeveloped bone architecture, low bone strength and a high degree of fat infiltration in the lower extremity musculature. The present study aims to determine if such a profile exists in ambulatory children with mild CP and if excess fat infiltration extends into the bone marrow. Ambulatory children with mild spastic CP and typically developing children (4 to 11years; 12/group) were compared. Magnetic resonance imaging was used to estimate cortical bone, bone marrow and total bone volume and width, bone strength [i.e., section modulus (Z) and polar moment of inertia (J)], and bone marrow fat concentration in the midtibia, and muscle volume, intermuscular, subfascial, and subcutaneous adipose tissue (AT) volume and intramuscular fat concentration in the midleg. Accelerometer-based activity monitors worn on the ankle were used to assess physical activity. There were no group differences in age, height, body mass, body mass percentile, BMI, BMI percentile or tibia length, but children with CP had lower height percentile (19th vs. 50th percentile) and total physical activity counts (44%) than controls (both p<0.05). Children with CP also had lower cortical bone volume (30%), cortical bone width in the posterior (16%) and medial (32%) portions of the shaft, total bone width in the medial-lateral direction (15%), Z in the medial-lateral direction (34%), J (39%) and muscle volume (39%), and higher bone marrow fat concentration (82.1±1.8% vs. 80.5±1.9%), subfascial AT volume (3.3 fold) and intramuscular fat concentration (25.0±8.0% vs. 16.1±3.3%) than controls (all p<0.05). When tibia length was statistically controlled, all group differences in bone architecture, bone strength, muscle volume and fat infiltration estimates, except posterior cortical bone width, were still present (all p<0.05). Furthermore, a higher intermuscular AT volume in children with CP compared to controls emerged (p<0.05). Ambulatory children with mild spastic CP exhibit an underdeveloped bone architecture and low bone strength in the midtibia and a greater infiltration of fat in the bone marrow and surrounding musculature compared to typically developing children. Whether the deficit in the musculoskeletal system of children with CP is associated with higher chronic disease risk and whether the deficit can be mitigated requires further investigation. Copyright © 2016 Elsevier Inc. All rights reserved.

The effect of operative fit and hydroxyapatite coating on the mechanical and biological response to porous implants.

PubMed

Dalton, J E; Cook, S D; Thomas, K A; Kay, J F

1995-01-01

Femoral intramedullary implants were constructed by threading 4.0-millimeter-thick disks with a titanium-alloy (Ti-6Al-4V) porous bead coating onto a two-millimeter-diameter threaded rod. Each porous-coated disk, which was 6.0, 8.0, 9.0, or 10.0 millimeters in diameter, was separated by a two-millimeter-thick acrylic disk with a diameter of ten millimeters. Implants with and without a hydroxyapatite coating of twenty-five micrometers were inserted into fifteen skeletally mature adult mongrel dogs. The femoral canal was sequentially reamed bilaterally to a ten-millimeter diameter, resulting in uniform initial implant-bone interface gaps of 0.0, 0.5, 1.0, and 2.0 millimeters. Each animal received paired hydroxyapatite-coated and uncoated implants. Three animals each were killed at four, eight, twelve, twenty-four, and fifty-two weeks after the implantation. The harvested femora were sectioned through the acrylic spacers, transverse to the long axis, to produce individual push-out test specimens for mechanical testing. Characteristics of interface attachment were determined with test fixtures that supported the surrounding bone to within 150 micrometers of the interface. Histological sections were prepared, and the amount of bone within the porous structure and the amount of the original gap that was filled with new bone were quantified with a computerized video image-analysis system. Mechanical attachment strength and bone ingrowth were found to increase with the time after implantation and with a decrease in the size of the gap. Placement of the implant in proximal (cancellous) compared with distal (cortical) locations had no significant effect on the strength of attachment, bone ingrowth, or gap-filling. However, implants with a large initial gap (1.0 or 2.0 millimeters) demonstrated greater attachment strength in cancellous bone than in cortical bone. With a few exceptions, hydroxyapatite-coated implants with an initial gap of 1.0 millimeter or less demonstrated significantly increased mechanical attachment strength and bone ingrowth at all time-periods. Interface attachment strengths were positively correlated with bone ingrowth, the time after implantation, the use of a hydroxyapatite coating, and decreasing initial gap size. Initial implant-bone apposition is thought to be a prerequisite for good biological fixation. This apposition is often not achieved because of the design of the implant or instruments and the operative technique. Poor initial fit during the operation may decrease the longevity of the implant. The results of the present study indicate that attachment strength and bone ingrowth are significantly affected by gaps in the interface, particularly those of more than 1.0 millimeter.(ABSTRACT TRUNCATED AT 400 WORDS)

Exercise countermeasures for bed-rest deconditioning

NASA Technical Reports Server (NTRS)

Greenleaf, John (Editor)

1993-01-01

The purpose for this 30-day bed rest study was to investigate the effects of short-term, high intensity isotonic and isokinetic exercise training on maintenance of working capacity (peak oxygen uptake), muscular strength and endurance, and on orthostatic tolerance, posture and gait. Other data were collected on muscle atrophy, bone mineralization and density, endocrine analyses concerning vasoactivity and fluid-electrolyte balance, muscle intermediary metabolism, and on performance and mood of the subjects. It was concluded that: The subjects maintained a relatively stable mood, high morale, and high esprit de corps throughout the study. Performance improved in nearly all tests in almost all the subjects. Isotonic training, as opposed to isokinetic exercise training, was associated more with decreasing levels of psychological tension, concentration, and motivation; and improvement in the quality of sleep. Working capacity (peak oxygen uptake) was maintained during bed rest with isotonic exercise training; it was not maintained with isokinetic or no exercise training. In general, there was no significant decrease in strength or endurance of arm or leg muscles during bed rest, in spite of some reduction in muscle size (atrophy) of some leg muscles. There was no effect of isotonic exercise training on orthostasis, since tilt-table tolerance was reduced similarly in all three groups following bed rest. Bed rest resulted in significant decreases of postural stability and self-selected step length, stride length, and walking velocity, which were not influenced by either exercise training regimen. Most pre-bed rest responses were restored by the fourth day of recovery.

A Randomized Trial on the Effect of Bone Tissue on Vibration-induced Muscle Strength Gain and Vibration-induced Reflex Muscle Activity

PubMed Central

Cidem, Muharrem; Karacan, İlhan; Diraçoğlu, Demirhan; Yıldız, Aysel; Küçük, Suat Hayri; Uludağ, Murat; Gün, Kerem; Özkaya, Murat; Karamehmetoğlu, Şafak Sahir

2014-01-01

Background: Whole-body vibration (WBV) induces reflex muscle activity and leads to increased muscle strength. However, little is known about the physiological mechanisms underlying the effects of whole-body vibration on muscular performance. Tonic vibration reflex is the most commonly cited mechanism to explain the effects of whole-body vibration on muscular performance, although there is no conclusive evidence that tonic vibration reflex occurs. The bone myoregulation reflex is another neurological mechanism used to explain the effects of vibration on muscular performance. Bone myoregulation reflex is defined as a reflex mechanism in which osteocytes exposed to cyclic mechanical loading induce muscle activity. Aims: The aim of this study was to assess whether bone tissue affected vibration-induced reflex muscle activity and vibration-induced muscle strength gain. Study Design: A prospective, randomised, controlled, double-blind, parallel-group clinical trial. Methods: Thirty-four participants were randomised into two groups. High-magnitude whole-body vibration was applied in the exercise group, whereas low-magnitude whole-body vibration exercises were applied in the control group throughout 20 sessions. Hip bone mineral density, isokinetic muscle strength, and plasma sclerostin levels were measured. The surface electromyography data were processed to obtain the Root Mean Squares, which were normalised by maximal voluntarily contraction. Results: In the exercise group, muscle strength increased in the right and left knee flexors (23.9%, p=0.004 and 27.5%, p<0.0001, respectively). However, no significant change was observed in the knee extensor muscle strength. There was no significant change in the knee muscle strength in the control group. The vibration-induced corrected Root Mean Squares of the semitendinosus muscle was decreased by 2.8 times (p=0.005) in the exercise group, whereas there was no change in the control group. Sclerostin index was decreased by 15.2% (p=0.031) in the exercise group and increased by 20.8% (p=0.028) in the control group. A change in the sclerostin index was an important predictor of a change in the vibration-induced normalised Root Mean Square of the semitendinosus muscle (R2=0.7, p=0.0001). Femoral neck bone mineral density was an important predictor of muscle strength gain (R2=0.26, p=0.035). Conclusion: This study indicates that bone tissue may have an effect on vibration-induced muscle strength gain and vibration-induced reflex muscle activity. Trial registration: ClinicalTrials.gov: NCT01310348. PMID:25207162

A Randomized Trial on the Effect of Bone Tissue on Vibration-induced Muscle Strength Gain and Vibration-induced Reflex Muscle Activity.

PubMed

Cidem, Muharrem; Karacan, Ilhan; Diraçoğlu, Demirhan; Yıldız, Aysel; Küçük, Suat Hayri; Uludağ, Murat; Gün, Kerem; Ozkaya, Murat; Karamehmetoğlu, Safak Sahir

2014-03-01

Whole-body vibration (WBV) induces reflex muscle activity and leads to increased muscle strength. However, little is known about the physiological mechanisms underlying the effects of whole-body vibration on muscular performance. Tonic vibration reflex is the most commonly cited mechanism to explain the effects of whole-body vibration on muscular performance, although there is no conclusive evidence that tonic vibration reflex occurs. The bone myoregulation reflex is another neurological mechanism used to explain the effects of vibration on muscular performance. Bone myoregulation reflex is defined as a reflex mechanism in which osteocytes exposed to cyclic mechanical loading induce muscle activity. The aim of this study was to assess whether bone tissue affected vibration-induced reflex muscle activity and vibration-induced muscle strength gain. A prospective, randomised, controlled, double-blind, parallel-group clinical trial. Thirty-four participants were randomised into two groups. High-magnitude whole-body vibration was applied in the exercise group, whereas low-magnitude whole-body vibration exercises were applied in the control group throughout 20 sessions. Hip bone mineral density, isokinetic muscle strength, and plasma sclerostin levels were measured. The surface electromyography data were processed to obtain the Root Mean Squares, which were normalised by maximal voluntarily contraction. In the exercise group, muscle strength increased in the right and left knee flexors (23.9%, p=0.004 and 27.5%, p<0.0001, respectively). However, no significant change was observed in the knee extensor muscle strength. There was no significant change in the knee muscle strength in the control group. The vibration-induced corrected Root Mean Squares of the semitendinosus muscle was decreased by 2.8 times (p=0.005) in the exercise group, whereas there was no change in the control group. Sclerostin index was decreased by 15.2% (p=0.031) in the exercise group and increased by 20.8% (p=0.028) in the control group. A change in the sclerostin index was an important predictor of a change in the vibration-induced normalised Root Mean Square of the semitendinosus muscle (R2=0.7, p=0.0001). Femoral neck bone mineral density was an important predictor of muscle strength gain (R2=0.26, p=0.035). This study indicates that bone tissue may have an effect on vibration-induced muscle strength gain and vibration-induced reflex muscle activity. ClinicalTrials.gov: NCT01310348.

Bone health measured using quantitative ultrasonography in adult males with muscular dystrophy

PubMed Central

Morse, C.I.; Smith, J.; Denny, A.; Tweedale, J.; Searle, N.D.; Winwood, K.; Onambele-Pearson, G.L.

2016-01-01

Objectives: To compare muscle and bone health markers in adult males (aged 20-59 yrs) with and without muscular dystrophy (MD). Methods: Participants included 11 Fascioscapulohumeral (FSH), 11 Becker’s (Be), 9 limb girdle (LG), 11 Duchenne (DMD), and 14 non-dystrophic controls (CTRL). Physical activity was assessed using Bone (BPAQ) and disability specific (PASIPD) questionnaires. Bone QUS provided T- and Z scores from the Distal Radius (DR) and Mid-shaft tibia (MST). Tibialis anterior cross sectional area (TAACSA) was measured using B-mode ultrasound. Grip strength was measured in all but DMD. Results: Physical activity was lower in DMD, FSH and BeMD than CTRL (P<0.05), and lower in DMD than other MDs (P<0.01). T and Z scores were lower in DMD and Be than CTRL (DR, P<0.05); and lower in DMD than CTRL, LG, and FSH (MST, P<0.01). TAACSA and grip strength was 35-59% and 50-58% smaller in MD than CTRL, respectively (P<0.01). Within MD, BPAQ correlated with bone QUS measures (r=0.42-0.38, P<0.01). PASIPD correlated with grip strength (r=0.65, P<0.01) and TAACSA (r=0.46, P<0.01). Conclusion: Muscle size, strength, and bone health was lower in adult males with MD compared to adult males without MD, the extent of this is partially determined by physical activity. PMID:27973386

Bone health measured using quantitative ultrasonography in adult males with muscular dystrophy.

PubMed

Morse, C I; Smith, J; Denny, A; Tweedale, J; Searle, N D; Winwood, K; Onambele-Pearson, G L

2016-12-14

To compare muscle and bone health markers in adult males (aged 20-59 yrs) with and without muscular dystrophy (MD). Participants included 11 Fascioscapulohumeral (FSH), 11 Becker's (Be), 9 limb girdle (LG), 11 Duchenne (DMD), and 14 non-dystrophic controls (CTRL). Physical activity was assessed using Bone (BPAQ) and disability specific (PASIPD) questionnaires. Bone QUS provided T- and Z scores from the Distal Radius (DR) and Mid-shaft tibia (MST). Tibialis anterior cross sectional area (TA ACSA ) was measured using B-mode ultrasound. Grip strength was measured in all but DMD. Physical activity was lower in DMD, FSH and BeMD than CTRL (P<0.05), and lower in DMD than other MDs (P<0.01). T and Z scores were lower in DMD and Be than CTRL (DR, P<0.05); and lower in DMD than CTRL, LG, and FSH (MST, P<0.01). TA ACSA and grip strength was 35-59% and 50-58% smaller in MD than CTRL, respectively (P<0.01). Within MD, BPAQ correlated with bone QUS measures (r=0.42-0.38, P<0.01). PASIPD correlated with grip strength (r=0.65, P<0.01) and TA ACSA (r=0.46, P<0.01). Muscle size, strength, and bone health was lower in adult males with MD compared to adult males without MD, the extent of this is partially determined by physical activity.

Core Research Program, Year 5

NASA Technical Reports Server (NTRS)

2002-01-01

Dramatic losses of bone mineral density (BMD) and muscle strength are two of the best documented changes observed in humans after prolonged exposure to microgravity. Recovery of muscle upon return to a 1-G environment is well studied, however, far less is known about the rate and completeness of BMD recovery to pre-flight values. Using the mature tail-suspended adult rat model, this proposal will focus on the temporal course of recovery in tibial bone following a 28-d period of skeletal unloading. Through the study of bone density and muscle strength in the same animal, time-points during recovery from simulated microgravity will be identified when bone is at an elevated risk for fracture. These will occur due to the rapid recovery of muscle strength coupled with a slower recovery of bone, producing a significant mismatch in functional strength of these two tissues. Once the time-point of maximal mismatch is defined, various mechanical and pharmacological interventions will be tested at and around this time-point in attempt to minimize the functional difference of bone and muscle. The outcomes of this research will have high relevance for optimizing the rehabilitation of astronauts upon return to Earth, as well as upon landing on the Martian surface before assuming arduous physical tasks. Further. it will impact significantly on rehabilitation issues common to patients experiencing long periods of limb immobilization or bed rest.

Gradual decline in mobility with the adoption of food production in Europe

PubMed Central

Ruff, Christopher B.; Holt, Brigitte; Niskanen, Markku; Sladek, Vladimir; Berner, Margit; Garofalo, Evan; Garvin, Heather M.; Hora, Martin; Junno, Juho-Antti; Schuplerova, Eliska; Vilkama, Rosa; Whittey, Erin

2015-01-01

Increased sedentism during the Holocene has been proposed as a major cause of decreased skeletal robusticity (bone strength relative to body size) in modern humans. When and why declining mobility occurred has profound implications for reconstructing past population history and health, but it has proven difficult to characterize archaeologically. In this study we evaluate temporal trends in relative strength of the upper and lower limb bones in a sample of 1,842 individuals from across Europe extending from the Upper Paleolithic [11,000–33,000 calibrated years (Cal y) B.P.] through the 20th century. A large decline in anteroposterior bending strength of the femur and tibia occurs beginning in the Neolithic (∼4,000–7,000 Cal y B.P.) and continues through the Iron/Roman period (∼2,000 Cal y B.P.), with no subsequent directional change. Declines in mediolateral bending strength of the lower limb bones and strength of the humerus are much smaller and less consistent. Together these results strongly implicate declining mobility as the specific behavioral factor underlying these changes. Mobility levels first declined at the onset of food production, but the transition to a more sedentary lifestyle was gradual, extending through later agricultural intensification. This finding only partially supports models that tie increased sedentism to a relatively abrupt Neolithic Demographic Transition in Europe. The lack of subsequent change in relative bone strength indicates that increasing mechanization and urbanization had only relatively small effects on skeletal robusticity, suggesting that moderate changes in activity level are not sufficient stimuli for bone deposition or resorption. PMID:26060299

Bone Health Monitoring in Astronauts: Recommended Use of Quantitative Computed Tomography [QCT] for Clinical and Operational Decisions

NASA Technical Reports Server (NTRS)

Sibonga, J. D.; Truskowski, P.

2010-01-01

This slide presentation reviews the concerns that astronauts in long duration flights might have a greater risk of bone fracture as they age than the general population. A panel of experts was convened to review the information and recommend mechanisms to monitor the health of bones in astronauts. The use of Quantitative Computed Tomography (QCT) scans for risk surveillance to detect the clinical trigger and to inform countermeasure evaluation is reviewed. An added benefit of QCT is that it facilitates an individualized estimation of bone strength by Finite Element Modeling (FEM), that can inform approaches for bone rehabilitation. The use of FEM is reviewed as a process that arrives at a composite number to estimate bone strength, because it integrates multiple factors.

Follistatin-like 3 is a mediator of exercise-driven bone formation and strengthening

PubMed Central

Nam, J; Perera, P; Gordon, R; Jeong, Y; Blazek, AD; Kim, DG; Tee, BC; Sun, Z; Eubank, TD; Zhao, Y; Lablebecioglu, B; Liu, S; Litsky, A; Weisleder, NL; Lee, BS; Butterfield, T; Schneyer, AL; Agarwal, S

2015-01-01

Exercise is vital for maintaining bone strength and architecture. Follistatin like 3 (FSTL3), a member of Follistatin family, is a mechanosensitive protein upregulated in response to exercise and is involved in regulating musculoskeletal health, we investigated the potential role of FSTL3 in exercise-driven bone remodeling. Exercise-dependent regulation of bone structure and functions was compared in mice with global Fstl3 gene deletion (Fstl3−/−) and their age-matched Fstl3+/+ littermates. Mice were exercised by low-intensity treadmill walking. The mechanical properties and mineralization were determined by μCT, three-point bending test and sequential incorporation of calcein and alizarin complexone. ELISA, Western-blot analysis and qRT-PCR were used to analyze the regulation of FSTL3 and associated molecules in the serum specimens and tissues. Daily exercise significantly increased circulating FSTL3 levels in mice, rats and humans. Compared to age-matched littermates, Fstl3−/− mice exhibited significantly lower fracture tolerance, having greater stiffness, but lower strain at fracture and yield energy. Furthermore, increased levels of circulating FSTL3 in young mice paralleled greater strain at fracture compared to the lower levels of FSTL3 in older mice. More significantly, Fstl3−/− mice exhibited loss of mechanosensitivity and irresponsiveness to exercise-dependent bone formation as compared to their Fstl3+/+ littermates. In addition, FSTL3 gene deletion resulted in loss of exercise-dependent sclerostin regulation in osteocytes and osteoblasts, as compared to Fstl3+/+ osteocytes and osteoblasts, in vivo and in vitro. The data identifies FSTL3 as a critical mediator of exercise-dependent bone formation and strengthening and point to its potential role in bone health and in musculoskeletal diseases. PMID:25937185

Gut microbiota-bone axis.

PubMed

Villa, Christopher R; Ward, Wendy E; Comelli, Elena M

2017-05-24

The gut microbiota (GM) is an important regulator of body homeostasis, including intestinal and extra-intestinal effects. This review focuses on the GM-bone axis, which we define as the effect of the gut-associated microbial community or the molecules they synthesize, on bone health. While research in this field is limited, findings from preclinical studies support that gut microbes positively impact bone mineral density and strength parameters. Moreover, administration of beneficial bacteria (probiotics) in preclinical models has demonstrated higher bone mineralization and greater bone strength. The preferential bacterial genus that has shown these beneficial effects in bone is Lactobacillus and thus lactobacilli are among the best candidates for future clinical intervention trials. However, their effectiveness is dependent on stage of development, as early life constitutes an important time for impacting bone health, perhaps via modulation of the GM. In addition, sex-specific difference also impacts the efficacy of the probiotics. Although auspicious, many questions regarding the GM-bone axis require consideration of potential mechanisms; sex-specific efficacy; effective dose of probiotics; and timing and duration of treatment.

Lycopene treatment against loss of bone mass, microarchitecture and strength in relation to regulatory mechanisms in a postmenopausal osteoporosis model.

PubMed

Ardawi, Mohammed-Salleh M; Badawoud, Mohammed H; Hassan, Sherif M; Rouzi, Abdulrahim A; Ardawi, Jumanah M S; AlNosani, Nouf M; Qari, Mohammed H; Mousa, Shaker A

2016-02-01

Lycopene supplementation decreases oxidative stress and exhibits beneficial effects on bone health, but the mechanisms through which it alters bone metabolism in vivo remain unclear. The present study aims to evaluate the effects of lycopene treatment on postmenopausal osteoporosis. Six-month-old female Wistar rats (n=264) were sham-operated (SHAM) or ovariectomized (OVX). The SHAM group received oral vehicle only and the OVX rats were randomized into five groups receiving oral daily lycopene treatment (mg/kg body weight per day): 0 OVX (control), 15 OVX, 30 OVX, and 45 OVX, and one group receiving alendronate (ALN) (2μg/kg body weight per day), for 12weeks. Bone densitometry measurements, bone turnover markers, biomechanical testing, and histomorphometric analysis were conducted. Micro computed tomography was also used to evaluate changes in microarchitecture. Lycopene treatment suppressed the OVX-induced increase in bone turnover, as indicated by changes in biomarkers of bone metabolism: serum osteocalcin (s-OC), serum N-terminal propeptide of type 1 collagen (s-PINP), serum crosslinked carboxyterminal telopeptides (s-CTX-1), and urinary deoxypyridinoline (u-DPD). Significant improvement in OVX-induced loss of bone mass, bone strength, and microarchitectural deterioration was observed in lycopene-treated OVX animals. These effects were observed mainly at sites rich in trabecular bone, with less effect in cortical bone. Lycopene treatment down-regulated osteoclast differentiation concurrent with up-regulating osteoblast together with glutathione peroxidase (GPx) catalase (CAT) and superoxide dismutase (SOD) activities. These findings demonstrate that lycopene treatment in OVX rats primarily suppressed bone turnover to restore bone strength and microarchitecture. Copyright © 2015. Published by Elsevier Inc.

Development of implants composed of bioactive materials for bone repair

NASA Astrophysics Data System (ADS)

Xiao, Wei

The purpose of this Ph.D. research was to address the clinical need for synthetic bioactive materials to heal defects in non-loaded and loaded bone. Hollow hydroxyapatite (HA) microspheres created in a previous study were evaluated as a carrier for controlled release of bone morphogenetic protein-2 (BMP2) in bone regeneration. New bone formation in rat calvarial defects implanted with BMP2-loaded microspheres (43%) was significantly higher than microspheres without BMP2 (17%) at 6 weeks postimplantation. Then hollow HA microspheres with a carbonate-substituted composition were prepared to improve their resorption rate. Hollow HA microspheres with 12 wt. % of carbonate showed significantly higher new bone formation (73 +/- 8%) and lower residual HA (7 +/- 2%) than stoichiometric HA microspheres (59 +/- 2% new bone formation; 21 +/- 3% residual HA). The combination of carbonate-substituted hollow HA microspheres and clinically-safe doses of BMP2 could provide promising implants for healing non-loaded bone defects. Strong porous scaffolds of bioactive silicate (13-93) glass were designed with the aid of finite-element modeling, created by robocasting and evaluated for loaded bone repair. Scaffolds with a porosity gradient to mimic human cortical bone showed a compressive strength of 88 +/- 20 MPa, a flexural strength of 34 +/- 5 MPa and the ability to support bone infiltration in vivo. The addition of a biodegradable polylactic acid (PLA) layer to the external surface of these scaffolds increased their load-bearing capacity in four-point bending by 50% and dramatically enhanced their work of fracture, resulting in a "ductile" mechanical response. These bioactive glass-PLA composites, combining bioactivity, high strength, high work of fracture and an internal architecture conducive to bone infiltration, could provide optimal implants for structural bone repair.

Bone geometry, volumetric bone mineral density, microarchitecture and estimated bone strength in Caucasian females with systemic lupus erythematosus. A cross-sectional study using HR-pQCT.

PubMed

Hansen, Stinus; Gudex, Claire; Åhrberg, Fabian; Brixen, Kim; Voss, Anne

2014-12-01

Patients with systemic lupus erythematosus (SLE) have an increased risk of fracture. We used high resolution peripheral quantitative computed tomography (HR-pQCT) to measure bone geometry, volumetric bone mineral density (vBMD), cortical and trabecular microarchitecture and estimated bone strength by finite element analysis (FEA) at the distal radius and tibia to assess bone characteristics beyond BMD that may contribute to the increased risk of fracture. Thirty-three Caucasian women with SLE (median age 48, range 21-64 years) and 99 controls (median age 45, range 21-64 years) were studied. Groups were comparable in radius regarding geometry and vBMD, but SLE patients had lower trabecular number (-7%, p < 0.05), higher trabecular separation (13%, p < 0.05) and lower FEA-estimated failure load compared to controls (-10%, p < 0.05). In tibia, SLE patients had lower total vBMD (-11%, p < 0.01), cortical area (-14%, p < 0.001) and cortical thickness (-16%, p < 0.001) and higher trabecular area (8%, p < 0.05). In subgroup analyses of the premenopausal participants (SLE n = 21, controls n = 63), SLE patients had significantly lower trabecular bone volume fraction [(BV/TV); -17%, p < 0.01], trabecular number (-9%, p < 0.01), trabecular thickness (-9%, p < 0.05) and higher trabecular separation (13%, p < 0.01) and trabecular network inhomogeneity (14%, p < 0.05) in radius along with lower BV/TV (-15%, p < 0.01) and higher trabecular separation (11%, p < 0.05) in tibia. FEA-estimated bone strength was lower in both radius (-11%, p < 0.01) and tibia (-10%, p < 0.05). In conclusion, Caucasian women with SLE compared to controls had fewer and more widely separated trabeculae and lower estimated bone strength in radius and lower total vBMD, cortical area and thickness in tibia.

Ethnic differences in bone geometry between White, Black and South Asian men in the UK.

PubMed

Zengin, A; Pye, S R; Cook, M J; Adams, J E; Wu, F C W; O'Neill, T W; Ward, K A

2016-10-01

Relatively little is known about the bone health of ethnic groups within the UK and data are largely restricted to women. The aim of this study was to investigate ethnic differences in areal bone mineral density (aBMD), volumetric bone mineral density (vBMD), bone geometry and strength in UK men. White European, Black Afro-Caribbean and South Asian men aged over 40years were recruited from Greater Manchester, UK. aBMD at the spine, hip, femoral neck and whole body were measured by DXA. Bone geometry, strength and vBMD were measured at the radius and tibia using pQCT at the metaphysis (4%) and diaphysis (50% radius; 38% tibia) sites. Adjustments were made for age, weight and height. Black men had higher aBMD at the whole body, total hip and femoral neck compared to White and South Asian men independent of body size adjustments, with no differences between the latter two groups. White men had longer hip axis lengths than both Black and South Asian men. There were fewer differences in vBMD but White men had significantly lower cortical vBMD at the tibial diaphysis than Black and South Asian men (p<0.001). At the tibia and radius diaphysis, Black men had larger bones with thicker cortices and greater bending strength than the other groups. There were fewer differences between White and South Asian men. At the metaphysis, South Asian men had smaller bones (p=0.02) and lower trabecular vBMD at the tibia (p=0.003). At the diaphysis, after size-correction, South Asian men had similar sized bones but thinner cortices than White men; measures of strength were not broadly reduced in the South Asian men. Combining pQCT and DXA measurements has given insight into differences in bone phenotype in men from different ethnic backgrounds. Understanding such differences is important in understanding the aetiology of male osteoporosis. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

The peak bone mass concept: is it still relevant?

PubMed

Schönau, Eckhard

2004-08-01

The peak bone mass concept implies that optimal skeletal development during childhood and adolescence will prevent fractures in late adulthood. This concept is based on the observation that areal bone density increases with growth during childhood, is highest around 20 years of age and declines thereafter. However, it is now clear that strong bones in the youngster do not necessarily lead to a fracture-free old age. In the recent bone densitometric literature, the terms bone mass and bone density are typically used synonymously. In physics, density has been defined as the mass of a body divided by its volume. In clinical practice and science, "bone density" usually has a different meaning-the degree to which a radiation beam is attenuated by a bone, as judged from a two-dimensional projection image (areal bone density). The attenuation of a radiation beam does not only depend on physical density, but also on bone size. A small bone therefore has a lower areal bone density than a larger bone, even if the physical density is the same. Consequently, a low areal bone density value can simply reflect the small size of an otherwise normal bone. At present, bone mass analysis is very useful for epidemiological studies on factors that may have an impact on bone development. There is an ongoing discussion about whether the World Health Organization (WHO) definition of osteoporosis is over-simplistic and requires upgrading to include indices representing the distribution of bone and mineral (bone strength indices). The following suggestions and recommendations outline a new concept: bone mass should not be related to age. There is now more and more evidence that bone mass should be related to bone size or muscle function. Thus analyzed, there is no such entity as a "peak bone mass". Many studies are currently under way to evaluate whether these novel approaches increase sensitivity and specificity of fracture prediction in an individual. Furthermore, the focus of many bone researchers is shifting away from bone mass to bone geometry or bone strength. Bone mass is one surrogate marker of bone strength. Widely available techniques for measurement of bone mass, such as dual-energy X-ray absorptiometry, radiogrammetry, and computed tomography, can also be used to measure variables of bone geometry such as cortical thickness, cortical area, and moment of inertia.

Quantifying leisure physical activity and its relation to bone density and strength.

PubMed

Shedd, Kristine M; Hanson, Kathy B; Alekel, D Lee; Schiferl, Daniel J; Hanson, Laura N; Van Loan, Marta D

2007-12-01

Compare three published methods of quantifying physical activity (total activity, peak strain, and bone-loading exposure (BLE) scores) and identify their associations with areal bone mineral density (aBMD), volumetric BMD (vBMD), and bone strength. Postmenopausal women (N = 239; mean age: 53.8 yr) from Iowa (ISU) and California (UCD) completed the Paffenbarger Physical Activity Questionnaire, which was scored with each method. Dual energy x-ray absorptiometry assessed aBMD at the spine, hip, and femoral neck, and peripheral quantitative computed tomography (pQCT) measured vBMD and bone strength properties at the distal tibia and midshaft femur. UCD women had higher total activity scores and hours per week of leisure activity. All scoring methods were correlated with each other. No method was associated with aBMD. Peak strain score was negatively associated with polar moment of inertia and strength-strain index at the tibia, and total activity score was positively associated with cortical area and thickness at the femur. Separating by geographic site, the peak strain and hip BLE scores were negatively associated with pQCT measures at the tibia and femur among ISU subjects. Among UCD women, no method was significantly associated with any tibia measure, but total activity score was positively associated with measures at the femur (P < 0.05 for all associations). Given the significantly greater hours per week of leisure activity done by UCD subjects, duration may be an important determinant of the effect physical activity has on bone. The positive association between leisure physical activity (assessed by the total activity score) and cortical bone measures in postmenopausal women may indicate a lifestyle factor that can help offset age-related bone loss.

Analysis of the independent power of age-related, anthropometric and mechanical factors as determinants of the structure of radius and tibia in normal adults. A pQCT study.

PubMed

Reina, P; Cointry, G R; Nocciolino, L; Feldman, S; Ferretti, J L; Rittweger, J; Capozza, R F

2015-03-01

To compare the independent influence of mechanical and non-mechanical factors on bone features, multiple regression analyses were performed between pQCT indicators of radius and tibia bone mass, mineralization, design and strength as determined variables, and age or time since menopause (TMP), body mass, bone length and regional muscles' areas as selected determinant factors, in Caucasian, physically active, untrained healthy men and pre- and post-menopausal women. In men and pre-menopausal women, the strongest influences were exerted by muscle area on radial features and by both muscle area and bone length on the tibia. Only for women, was body mass a significant factor for tibia traits. In men and pre-menopausal women, mass/design/strength indicators depended more strongly on the selected determinants than the cortical vBMD did (p<0.01-0.001 vs n.s.), regardless of age. However, TMP was an additional factor for both bones (p<0.01-0.001). The selected mechanical factors (muscle size, bone lengths) were more relevant than age/TMP or body weight to the development of allometrically-related bone properties (mass/design/strength), yet not to bone tissue 'quality' (cortical vBMD), suggesting a determinant, rather than determined role for cortical stiffness. While the mechanical impacts of muscles and bone levers on bone structure were comparable in men and pre-menopausal women, TMP exerted a stronger impact than allometric or mechanical factors on bone properties, including cortical vBMD.

Bed Rest and Immobilization: Risk Factors for Bone Loss

MedlinePlus

... Loss Bed Rest and Immobilization: Risk Factors for Bone Loss Like muscle, bone is living tissue that ... bones adjust to the state of weightlessness. Maintaining Bone Health In general, healthy people who undergo prolonged ...

Brillouin light scattering spectroscopy for tissue engineering application

NASA Astrophysics Data System (ADS)

Akilbekova, Dana; Yakupov, Talgat; Ogay, Vyacheslav; Umbayev, Bauyrzhan; Yakovlev, Vladislav V.; Utegulov, Zhandos N.

2018-02-01

Biomechanical properties of mammalian bones, such as strength, toughness and plasticity, are essential for understanding how microscopic scale mechanical features can link to macroscale bones' strength and fracture resistance. We employ Brillouin light scattering (BLS) micro-spectroscopy for local assessment of elastic properties of bones under compression and the efficacy of the tissue engineering approach based on heparin-conjugated fibrin (HCF) hydrogels, bone morphogenic proteins (BMPs) and osteogenic stem cells in the regeneration of the bone tissues. BLS is noninvasive and label-free imaging modality for probing mechanical properties of hard tissues that can give information on structure-function properties of normal and pathological tissues. Results showed that HCF gels containing combination of all factors had the best effect with complete defect regeneration at week 9 and that the bones with fully consolidated fractures have higher values of elastic moduli compared to the bones with defects.

Sex- and Age-Related Differences in Bone Microarchitecture in Men Relative to Women Assessed by High-Resolution Peripheral Quantitative Computed Tomography

PubMed Central

Amin, Shreyasee; Khosla, Sundeep

2012-01-01

The trabecular and cortical compartments of bone each contributes to bone strength. Until recently, assessment of trabecular and cortical microstructure has required a bone biopsy. Now, trabecular and cortical microstructure of peripheral bone sites can be determined noninvasively using high-resolution peripheral quantitative computed tomography (HR-pQCT). Studies that have used HR-pQCT to evaluate cohorts of both men and women have provided novel insights into the changes in bone microarchitecture that occur with age between the sexes, which may help to explain the lower fracture incidence in older men relative to women. This review will highlight observations from these studies on both the sex- and age-related differences in trabecular and cortical microstructure that may underlie the differences in bone strength, and thereby fracture risk, between men and women. PMID:22496983

Genetic selection to increase bone strength affects prevalence of keel bone damage and egg parameters in commercially housed laying hens.

PubMed

Stratmann, A; Fröhlich, E K F; Gebhardt-Henrich, S G; Harlander-Matauschek, A; Würbel, H; Toscano, M J

2016-05-01

The prevalence of keel bone damage as well as external egg parameters of 2 pure lines divergently selected for high (H) and low (L) bone strength were investigated in 2 aviary systems under commercial conditions. A standard LSL hybrid was used as a reference group. Birds were kept mixed per genetic line (77 hens of the H and L line and 201 or 206 hens of the LSL line, respectively, per pen) in 8 pens of 2 aviary systems differing in design. Keel bone status and body mass of 20 focal hens per line and pen were assessed at 17, 18, 23, 30, 36, 43, 52, and 63 wk of age. External egg parameters (i.e., egg mass, eggshell breaking strength, thickness, and mass) were measured using 10 eggs per line at both 38 and 57 wk of age. Body parameters (i.e. tarsus and third primary wing feather length to calculate index of wing loading) were recorded at 38 wk of age and mortality per genetic line throughout the laying cycle. Bone mineral density (BMD) of 15 keel bones per genetic line was measured after slaughter to confirm assignment of the experimental lines. We found a greater BMD in the H compared with the L and LSL lines. Fewer keel bone fractures and deviations, a poorer external egg quality, as well as a lower index of wing loading were found in the H compared with the L line. Mortality was lower and production parameters (e.g., laying performance) were higher in the LSL line compared with the 2 experimental lines. Aviary design affected prevalence of keel bone damage, body mass, and mortality. We conclude that selection of specific bone traits associated with bone strength as well as the related differences in body morphology (i.e., lower index of wing loading) have potential to reduce keel bone damage in commercial settings. Also, the housing environment (i.e., aviary design) may have additive effects. © 2016 Poultry Science Association Inc.

[Effect of high impact movements on body composition, strength and bone mineral density on women over 60 years].

PubMed

Ramírez-Villada, Jhon F; León-Ariza, Henry H; Argüello-Gutiérrez, Yenny P; Porras-Ramírez, Keyla A

2016-01-01

Osteoporosis is characterised by loss of bone mass and deterioration of bone tissue microarchitecture that leads to fragility related to the risk of fractures. The aim of the study is to analyse the effects of a training program based on explosive movements and impact, assessed in a swimming pool, on body composition, explosive strength and bone mineral density in women over 60 years old. A total of 35 healthy physically active women (60±4.19 years) were divided into a training pool group using multi jumps (JG) and a control group (CG). JG trained for 24 weeks, 3 times a week, an hour and a half per session. Body composition testing, explosive strength, and bone mineral density were assessed before and after the program. There were differences in the explosive force (JG vs CG=P<.05 to .001) and the estimated power (JG vs CG=P<.05 to .002) between JG vs CG, with significant increases in JG. There were no significant differences in the percentage of fat and lean mass, bone mineral density lumbar and femoral between groups, although slightly significant increases in bone mineral density lumbar and femoral could be seen in JG after program implementation (JG pre-test vs JG post- test=P<.05). The training program with impact and explosive movements assessed in a pool induces gains in muscle strength and power with slight adaptations in body mass index in women over 60 years. Copyright © 2015 SEGG. Published by Elsevier Espana. All rights reserved.

Prediction of trabecular bone qualitative properties using scanning quantitative ultrasound

PubMed Central

Qin, Yi-Xian; Lin, Wei; Mittra, Erik; Xia, Yi; Cheng, Jiqi; Judex, Stefan; Rubin, Clint; Müller, Ralph

2012-01-01

Microgravity induced bone loss represents a critical health problem in astronauts, particularly occurred in weight-supporting skeleton, which leads to osteopenia and increase of fracture risk. Lack of suitable evaluation modality makes it difficult for monitoring skeletal status in long term space mission and increases potential risk of complication. Such disuse osteopenia and osteoporosis compromise trabecular bone density, and architectural and mechanical properties. While X-ray based imaging would not be practical in space, quantitative ultrasound may provide advantages to characterize bone density and strength through wave propagation in complex trabecular structure. This study used a scanning confocal acoustic diagnostic and navigation system (SCAN) to evaluate trabecular bone quality in 60 cubic trabecular samples harvested from adult sheep. Ultrasound image based SCAN measurements in structural and strength properties were validated by μCT and compressive mechanical testing. This result indicated a moderately strong negative correlations observed between broadband ultrasonic attenuation (BUA) and μCT-determined bone volume fraction (BV/TV, R2=0.53). Strong correlations were observed between ultrasound velocity (UV) and bone’s mechanical strength and structural parameters, i.e., bulk Young’s modulus (R2=0.67) and BV/TV (R2=0.85). The predictions for bone density and mechanical strength were significantly improved by using a linear combination of both BUA and UV, yielding R2=0.92 for BV/TV and R2=0.71 for bulk Young’s modulus. These results imply that quantitative ultrasound can characterize trabecular structural and mechanical properties through measurements of particular ultrasound parameters, and potentially provide an excellent estimation for bone’s structural integrity. PMID:23976803

Laterality and grip strength influence hand bone micro-architecture in modern humans, an HRpQCT study.

PubMed

Reina, Nicolas; Cavaignac, Etienne; Trousdale, William H; Laffosse, Jean-Michel; Braga, José

2017-06-01

It is widely hypothesized that mechanical loading, specifically repetitive low-intensity tasks, influences the inner structure of cancellous bone. As such, there is likely a relationship between handedness and bone morphology. The aim of this study is to determine patterns in trabecular bone between dominant and non-dominant hands in modern humans. Seventeen healthy patients between 22 and 32 years old were included in the study. Radial carpal bones (lunate, capitate, scaphoid, trapezium, trapezoid, 1st, 2nd and 3rd metacarpals) were analyzed with high-resolution micro-computed tomography. Additionally, crush and pinch grip were recorded. Factorial analysis indicated that bone volume ratio, trabeculae number (Tb.N), bone surface to volume ratio (BS.BV), body weight, stature and crush grip were all positively correlated with principal components 1 and 2 explaining 78.7% of the variance. Volumetric and trabecular endostructural parameters (BV/TV, BS/BV or Tb.Th, Tb.N) explain the observed inter-individual variability better than anthropometric or clinical parameters. Factors analysis regressions showed correlations between these parameters and the dominant side for crush strength for the lunate (r 2 = 0.640, P < 0.0001), trapezium (r 2 = 0.836, P < 0.0001) and third metacarpal (r 2 = 0.763). However, despite a significant lateralization in grip strength for all patients, the endostructural variability between dominant and non-dominant sides was limited in perspective to inter-individual differences. In conclusion, handedness is unlikely to generate trabecular patterns of asymmetry. It appears, however, that crush strength can be considered for endostructural analysis in the modern human wrist. © 2017 Anatomical Society.

Chronic administration of anticonvulsants but not antidepressants impairs bone strength: clinical implications

PubMed Central

Gold, P W; Pavlatou, M G; Michelson, D; Mouro, C M; Kling, M A; Wong, M-L; Licinio, J; Goldstein, S A

2015-01-01

Major depression and bipolar disorder are associated with decreased bone mineral density (BMD). Antidepressants such as imipramine (IMIP) and specific serotonin reuptake inhibitors (SSRIs) have been implicated in reduced BMD and/or fracture in older depressed patients. Moreover, anticonvulsants such as valproate (VAL) and carbamazepine (CBZ) are also known to increase fracture rates. Although BMD is a predictor of susceptibility to fracture, bone strength is a more sensitive predictor. We measured mechanical and geometrical properties of bone in 68 male Sprague Dawley rats on IMIP, fluoxetine (FLX), VAL, CBZ, CBZ vehicle and saline (SAL), given intraperitoneally daily for 8 weeks. Distinct regions were tested to failure by four-point bending, whereas load displacement was used to determine stiffness. The left femurs were scanned in a MicroCT system to calculate mid-diaphyseal moments of inertia. None of these parameters were affected by antidepressants. However, VAL resulted in a significant decrease in stiffness and a reduction in yield, and CBZ induced a decrease in stiffness. Only CBZ induced alterations in mechanical properties that were accompanied by significant geometrical changes. These data reveal that chronic antidepressant treatment does not reduce bone strength, in contrast to chronic anticonvulsant treatment. Thus, decreased BMD and increased fracture rates in older patients on antidepressants are more likely to represent factors intrinsic to depression that weaken bone rather than antidepressants per se. Patients with affective illness on anticonvulsants may be at particularly high risk for fracture, especially as they grow older, as bone strength falls progressively with age. PMID:26035060

Evaluation of novel resorbable membranes for bone augmentation in a rat model.

PubMed

Zeng, Ni; van Leeuwen, Anne; Yuan, Huipin; Bos, Ruud R M; Grijpma, Dirk W; Kuijer, Roel

2016-02-01

Our study compared two novel, biodegradable poly(trimethylene carbonate) (PTMC) barrier membranes to clinically applied barrier membranes in maintaining volume of block autologous bone grafts in a rat mandible model. Two hundred and forty rats were included in this study. Block autologous bone grafts of 5 mm in diameter were harvested from the mandibular angles and transplanted onto the contralateral side. The bone grafts were either covered with a membrane or left uncovered. The applied membranes included pure PTMC membranes, biphasic calcium phosphate (BCP) incorporated PTMC composite membranes, expanded poly(tetrafluoroethylene) (e-PTFE) membranes (Tex) and collagen membranes (Geistlich Bio-Gide). After 2, 4 and 12 weeks, the rat mandibles were retrieved and analysed by histological evaluation and μCT quantification. The histological evaluation revealed that in time the block autologous bone graft was well integrated to the recipient bone via gradually maturing newly formed bone and did not show signs of resorption, independent of membrane coverage or types of membrane. μCT quantification showed the volume of the bone graft and recipient bone together was maintained by new bone formation and recipient bone resorption. Our study showed that the use of PTMC membranes and PTMC-BCP composite membranes resulted in similar bone remodelling to the collagen membranes and e-PTFE membranes and that the use of barrier membranes did not interfere with bone remodelling of the bone grafts and recipient bones. However, the used barrier membranes seemed not to contribute in maintaining the volume of block autologous bone grafts. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Reduced energy availability: implications for bone health in physically active populations.

PubMed

Papageorgiou, Maria; Dolan, Eimear; Elliott-Sale, Kirsty J; Sale, Craig

2018-04-01

The present review critically evaluates existing literature on the effects of short- and long-term low energy availability (EA) on bone metabolism and health in physically active individuals. We reviewed the literature on the short-term effects of low EA on markers of bone metabolism and the long-term effects of low EA on outcomes relating to bone health (bone mass, microarchitecture and strength, bone metabolic markers and stress fracture injury risk) in physically active individuals. Available evidence indicates that short-term low EA may increase markers of bone resorption and decrease markers of bone formation in physically active women. Bone metabolic marker responses to low EA are less well known in physically active men. Cross-sectional studies investigating the effects of long-term low EA suggest that physically active individuals who have low EA present with lower bone mass, altered bone metabolism (favouring bone resorption), reduced bone strength and increased risk for stress fracture injuries. Reduced EA has a negative influence on bone in both the short- and long-term, and every effort should be made to reduce its occurrence in physically active individuals. Future interventions are needed to explore the effects of long-term reduced EA on bone health outcomes, while short-term low EA studies are also required to give insight into the pathophysiology of bone alterations.

Finding the right fit: studying the biomechanics of under-tapping with varying thread depths and pitches.

PubMed

Jazini, Ehsan; Petraglia, Carmen; Moldavsky, Mark; Tannous, Oliver; Weir, Tristan; Saifi, Comron; Elkassabany, Omar; Cai, Yiwei; Bucklen, Brandon; O'Brien, Joseph; Ludwig, Steven C

2017-04-01

Compromise of pedicle screw purchase is a concern in maintaining rigid spinal fixation, especially with osteoporosis. Little consistency exists among various tapping techniques. Pedicle screws are often prepared with taps of a smaller diameter, which can further exacerbate inconsistency. The objective of this study was to determine whether a mismatch between tap thread depth (D) and thread pitch (P) and screw D and P affects fixation when under-tapping in osteoporotic bone. This study is a polyurethane foam block biomechanical analysis. A foam block osteoporotic bone model was used to compare pullout strength of pedicle screws with a 5.3 nominal diameter tap of varying D's and P's. Blocks were sorted into seven groups: (1) probe only; (2) 0.5-mm D, 1.5-mm P tap; (3) 0.5-mm D, 2.0-mm P tap; (4) 0.75-mm D, 2.0-mm P tap; (5) 0.75-mm D, 2.5-mm P tap; (6) 0.75-mm D, 3.0-mm P tap; and (7) 1.0-mm D, 2.5-mm P tap. A pedicle screw, 6.5 mm in diameter and 40 mm in length, was inserted to a depth of 40 mm. Axial pullout testing was performed at a rate of 5 mm/min on 10 blocks from each group. No significant difference was noted between groups under axial pullout testing. The mode of failure in the probe-only group was block fracture, occurring in 50% of cases. Among the other six groups, only one screw failed because of block fracture. The other 59 failed because of screw pullout. In an osteoporotic bone model, changing the D or P of the tap has no statistically significant effect on axial pullout. Osteoporotic bone might render tap features marginal. Our findings indicate that changing the characteristics of the tap D and P does not help with pullout strength in an osteoporotic model. The high rate of fracture in the probe-only group might imply the potential benefit of tapping to prevent catastrophic failure of bone. Copyright © 2016 Elsevier Inc. All rights reserved.

The Effects of a Transition to Minimalist Shoe Running on Intrinsic Foot Muscle Size.

PubMed

Johnson, A W; Myrer, J W; Mitchell, U H; Hunter, I; Ridge, S T

2016-02-01

A proposed benefit of minimalist shoe running is an increase in intrinsic foot muscle strength. This study examined change in intrinsic foot muscle size in runners transitioning to Vibram FiveFingers™ minimalist shoes compared to a control group running in traditional running shoes. We compare pre-transition size between runners who developed bone marrow edema to those who did not. 37 runners were randomly assigned to the Vibram FiveFingers™ group (n=18) or control group (n=19). Runners' bone marrow edema and intrinsic foot muscle size were measured at baseline and after 10 weeks. Total running volume was maintained by all runners. A significant increase in abductor hallucis cross-sectional area of 10.6% occurred in the Vibram FiveFingers™ group compared to the control group (p=0.01). There was no significant change in any of the other muscles examined (p>0.05). 8 of the Vibram FiveFingers™ runners, and 1 control runner developed bone marrow edema. Those who developed bone marrow edema, primarily women, had significantly smaller size in all assessed muscles (p≤0.05). Size of intrinsic foot muscles appears to be important in safely transitioning to minimalist shoe running. Perhaps intrinsic foot muscle strengthening may benefit runners wanting to transition to minimalist shoes. © Georg Thieme Verlag KG Stuttgart · New York.

Modeling of Stiffness and Strength of Bone at Nanoscale.

PubMed

Abueidda, Diab W; Sabet, Fereshteh A; Jasiuk, Iwona M

2017-05-01

Two distinct geometrical models of bone at the nanoscale (collagen fibril and mineral platelets) are analyzed computationally. In the first model (model I), minerals are periodically distributed in a staggered manner in a collagen matrix while in the second model (model II), minerals form continuous layers outside the collagen fibril. Elastic modulus and strength of bone at the nanoscale, represented by these two models under longitudinal tensile loading, are studied using a finite element (FE) software abaqus. The analysis employs a traction-separation law (cohesive surface modeling) at various interfaces in the models to account for interfacial delaminations. Plane stress, plane strain, and axisymmetric versions of the two models are considered. Model II is found to have a higher stiffness than model I for all cases. For strength, the two models alternate the superiority of performance depending on the inputs and assumptions used. For model II, the axisymmetric case gives higher results than the plane stress and plane strain cases while an opposite trend is observed for model I. For axisymmetric case, model II shows greater strength and stiffness compared to model I. The collagen-mineral arrangement of bone at nanoscale forms a basic building block of bone. Thus, knowledge of its mechanical properties is of high scientific and clinical interests.

Increased Antibiotic Release from a Bone Cement Containing Bacterial Cellulose

PubMed Central

Nakai, Takahisa; Enomoto, Koichi; Uchio, Yuji; Yoshino, Katsumi

2010-01-01

Background Major disadvantages of antibiotic bone cements include limited drug release and reduced strength resulting from the addition of high doses of antibiotics. Bacterial cellulose, a three-dimensional hydrophilic mesh, may retain antibiotics and release them gradually. We hypothesized that the addition of cellulose to antibiotic bone cement would improve mechanical strength and antibiotic release. Questions/purposes We therefore examined the mechanical strength and antibiotic release of cellulose antibiotic cement. Methods A high dose of antibiotics (5 g per 40 g cement powder) was incorporated into bacterial cellulose and then mixed with bone cement. We compared the compression strength, fracture toughness, fatigue life, and elution kinetics of this formulation with those of plain cement and a traditional antibiotic cement. Results The average values for compression strength, fracture toughness, and fatigue life of the cellulose antibiotic cement were 97%, 97%, and 78% of the values obtained for plain cement, respectively. The corresponding values for the traditional antibiotic cement were 79%, 82%, and 17%, respectively. The cumulative elution over 35 days was 129% greater from the cellulose antibiotic cement than from the traditional antibiotic cement. Conclusions With a high dose of antibiotics, incorporating cellulose into the bone cement prevented compression and fracture fragility, improved fatigue life, and increased antibiotic elution. Clinical Relevance Antibiotic cements containing cellulose may have applications in clinical situations that require high levels of antibiotic release and preservation of the mechanical properties of the cement. PMID:20945120

Computational assessment of press-fit acetabular implant fixation: the effect of implant design, interference fit, bone quality, and frictional properties.

PubMed

Janssen, D; Zwartelé, R E; Doets, H C; Verdonschot, N

2010-01-01

Patients suffering from rheumatoid arthritis typically have a poor subchondral bone quality, endangering implant fixation. Using finite element analysis (FEA) an investigation was made to find whether a press-fit acetabular implant with a polar clearance would reduce interfacial micromotions and improve fixation compared with a standard hemispherical design. In addition, the effects of interference fit, friction, and implant material were analysed. Cups were introduced into an FEA model of a human pelvis with simulated subchondral bone plasticity. The models were loaded with a loading configuration simulating two cycles of normal walking, during which contact stresses and interfacial micromotions were monitored. Subsequently, a lever-out simulation was performed to assess the fixation strength of the various cases. A flattened cup with good bone quality produced the lowest interfacial micromotions. Poor bone decreased the fixation strength regardless of the geometry of the cup. Increasing the interference fit of the flattened cup compensated for the loss of fixation strength caused by poor bone quality. In conclusion, a flattened cup did not significantly improve implant fixation over a hemispherical cup in the case of poor bone quality. However, implant fixation can be optimized by increasing interference fit and avoiding inferior frictional properties and low-stiffness implants.

Lightweight Open-Cell Scaffolds from Sea Urchin Spines with Superior Material Properties for Bone Defect Repair.

PubMed

Cao, Lei; Li, Xiaokang; Zhou, Xiaoshu; Li, Yong; Vecchio, Kenneth S; Yang, Lina; Cui, Wei; Yang, Rui; Zhu, Yue; Guo, Zheng; Zhang, Xing

2017-03-22

Sea urchin spines (Heterocentrotus mammillatus), with a hierarchical open-cell structure similar to that of human trabecular bone and superior mechanical property (compressive strength ∼43.4 MPa) suitable for machining to shape, were explored for potential applications of bone defect repair. Finite element analyses reveal that the compressive stress concentrates along the dense growth rings and dissipates through strut structures of the stereoms, indicating that the exquisite mesostructures play an important role in high strength-to-weight ratios. The fracture strength of magnesium-substituted tricalcium phosphate (β-TCMP) scaffolds produced by hydrothermal conversion of urchin spines is about 9.3 MPa, comparable to that of human trabecular bone. New bone forms along outer surfaces of β-TCMP scaffolds after implantation in rabbit femoral defects for one month and grows into the majority of the inner open-cell spaces postoperation in three months, showing tight interface between the scaffold and regenerative bone tissue. Fusion of beagle lumbar facet joints using a Ti-6Al-4V cage and β-TCMP scaffold can be completed within seven months with obvious biodegradation of the β-TCMP scaffold, which is nearly completely degraded and replaced by newly formed bone ten months after implantation. Thus, sea urchin spines suitable for machining to shape have advantages for production of biodegradable artificial grafts for bone defect repair.

Enhanced osteogenesis of β-tricalcium phosphate reinforced silk fibroin scaffold for bone tissue biofabrication.

PubMed

Lee, Dae Hoon; Tripathy, Nirmalya; Shin, Jae Hun; Song, Jeong Eun; Cha, Jae Geun; Min, Kyung Dan; Park, Chan Hum; Khang, Gilson

2017-02-01

Scaffolds, used for tissue regeneration are important to preserve their function and morphology during tissue healing. Especially, scaffolds for bone tissue engineering should have high mechanical properties to endure load of bone. Silk fibroin (SF) from Bombyx mori silk cocoon has potency as a type of biomaterials in the tissue engineering. β-tricalcium phosphate (β-TCP) as a type of bioceramics is also critical as biomaterials for bone regeneration because of its biocompatibility, osteoconductivity, and mechanical strength. The aim of this study was to fabricate three-dimensional SF/β-TCP scaffolds and access its availability for bone grafts through in vitro and in vivo test. The scaffolds were fabricated in each different ratios of SF and β-TCP (100:0, 75:25, 50:50, 25:75). The characterizations of scaffolds were conducted by FT-IR, compressive strength, porosity, and SEM. The in vitro and in vivo tests were carried out by MTT, ALP, RT-PCR, SEM, μ-CT, and histological staining. We found that the SF/β-TCP scaffolds have high mechanical strength and appropriate porosity for bone tissue engineering. The study showed that SF/β-TCP (75:25) scaffold exhibited the highest osteogenesis compared with other scaffolds. The results suggested that SF/β-TCP (75:25) scaffold can be applied as one of potential bone grafts for bone tissue engineering. Copyright © 2016. Published by Elsevier B.V.

Decreasing maternal myostatin programs adult offspring bone strength in a mouse model of osteogenesis imperfecta

PubMed Central

Oestreich, Arin K.; Kamp, William M.; McCray, Marcus G.; Carleton, Stephanie M.; Karasseva, Natalia; Lenz, Kristin L.; Jeong, Youngjae; Daghlas, Salah A.; Yao, Xiaomei; Wang, Yong; Pfeiffer, Ferris M.; Ellersieck, Mark R.; Schulz, Laura C.; Phillips, Charlotte L.

2016-01-01

During fetal development, the uterine environment can have effects on offspring bone architecture and integrity that persist into adulthood; however, the biochemical and molecular mechanisms remain unknown. Myostatin is a negative regulator of muscle mass. Parental myostatin deficiency (Mstntm1Sjl/+) increases muscle mass in wild-type offspring, suggesting an intrauterine programming effect. Here, we hypothesized that Mstntm1Sjl/+ dams would also confer increased bone strength. In wild-type offspring, maternal myostatin deficiency altered fetal growth and calvarial collagen content of newborn mice and conferred a lasting impact on bone geometry and biomechanical integrity of offspring at 4 mo of age, the age of peak bone mass. Second, we sought to apply maternal myostatin deficiency to a mouse model with osteogenesis imperfecta (Col1a2oim), a heritable connective tissue disorder caused by abnormalities in the structure and/or synthesis of type I collagen. Femora of male Col1a2oim/+ offspring from natural mating of Mstntm1Sjl/+ dams to Col1a2oim/+sires had a 15% increase in torsional ultimate strength, a 29% increase in tensile strength, and a 24% increase in energy to failure compared with age, sex, and genotype-matched offspring from natural mating of Col1a2oim/+ dams to Col1a2oim/+ sires. Finally, increased bone biomechanical strength of Col1a2oim/+ offspring that had been transferred into Mstntm1Sjl/+ dams as blastocysts demonstrated that the effects of maternal myostatin deficiency were conferred by the postimplantation environment. Thus, targeting the gestational environment, and specifically prenatal myostatin pathways, provides a potential therapeutic window and an approach for treating osteogenesis imperfecta. PMID:27821779

Decreasing maternal myostatin programs adult offspring bone strength in a mouse model of osteogenesis imperfecta.

PubMed

Oestreich, Arin K; Kamp, William M; McCray, Marcus G; Carleton, Stephanie M; Karasseva, Natalia; Lenz, Kristin L; Jeong, Youngjae; Daghlas, Salah A; Yao, Xiaomei; Wang, Yong; Pfeiffer, Ferris M; Ellersieck, Mark R; Schulz, Laura C; Phillips, Charlotte L

2016-11-22

During fetal development, the uterine environment can have effects on offspring bone architecture and integrity that persist into adulthood; however, the biochemical and molecular mechanisms remain unknown. Myostatin is a negative regulator of muscle mass. Parental myostatin deficiency (Mstn tm1Sjl/+ ) increases muscle mass in wild-type offspring, suggesting an intrauterine programming effect. Here, we hypothesized that Mstn tm1Sjl/+ dams would also confer increased bone strength. In wild-type offspring, maternal myostatin deficiency altered fetal growth and calvarial collagen content of newborn mice and conferred a lasting impact on bone geometry and biomechanical integrity of offspring at 4 mo of age, the age of peak bone mass. Second, we sought to apply maternal myostatin deficiency to a mouse model with osteogenesis imperfecta (Col1a2 oim ), a heritable connective tissue disorder caused by abnormalities in the structure and/or synthesis of type I collagen. Femora of male Col1a2 oim/+ offspring from natural mating of Mstn tm1Sjl/+ dams to Col1a2 oim/+ sires had a 15% increase in torsional ultimate strength, a 29% increase in tensile strength, and a 24% increase in energy to failure compared with age, sex, and genotype-matched offspring from natural mating of Col1a2 oim/+ dams to Col1a2 oim/+ sires. Finally, increased bone biomechanical strength of Col1a2 oim/+ offspring that had been transferred into Mstn tm1Sjl/+ dams as blastocysts demonstrated that the effects of maternal myostatin deficiency were conferred by the postimplantation environment. Thus, targeting the gestational environment, and specifically prenatal myostatin pathways, provides a potential therapeutic window and an approach for treating osteogenesis imperfecta.

Effect of strain of layer and age at photostimulation on egg production, egg quality, and bone strength.

PubMed

Silversides, F G; Korver, D R; Budgell, K L

2006-07-01

Bone strength in layers is a concern for economic reasons and animal welfare concerns. Bone characteristics were investigated in 3 strains of hens: Babcock B-300, a small-bodied commercial white-egg layer; ISA-Brown, a commercial brown-egg layer; and an unselected Brown Leghorn line (BL). After being reared together in a single pen with 8 h of light per day, hens were caged with 14 h of light per day. Half of the hens were caged at 18 wk of age and the other half at 20 wk of age, resulting in a 2-wk difference in the age at photostimulation. Body weights, egg production, feed efficiency, and egg quality were measured throughout production. At 15, 25, 50, and 74 wk of age, hens were euthanized for sampling of the radius and the humerus. Breaking strength of the radius and humerus was measured, and the area and density of trabecular (largely medullary bone) and cortical bone were measured using quantitative computed tomography. Egg production and feed conversion of ISA-Brown hens was as good as or better than that of Babcock B-300 hens, and both commercial strains had higher production than the BL. Photostimulation late delayed sexual maturity and improved albumen and shell characteristics but had only minor effects on egg production and did not affect the yolk weight. The delayed photostimulation resulting from caging 2 wk later affected the radius by increasing the area of the trabecular space at 50 wk of age and the density of the bone in the trabecular space at 74 wk of age. Breaking strength of the humerus at 25 wk of age was greater for the birds that were photostimulated late but was not different later in the trial. The humerus, but not the radius, of the BL had a greater breaking strength than that of the commercial strains, suggesting that selection has decreased humeral breaking strength.

The effect of whole-body vibration therapy on bone metabolism, motor function, and anthropometric parameters in women with postmenopausal osteoporosis.

PubMed

Luo, Xiaotian; Zhang, Jifeng; Zhang, Chi; He, Chengqi; Wang, Pu

2017-11-01

To review the research literature on the effectiveness of whole-body vibration (WBV) therapy in women with postmenopausal osteoporosis. A systematic review was conducted by two independent reviewers. Mean differences (MDs), standardized mean differences (SMDs), and 95% confidence intervals (CIs) were calculated, and heterogeneity was assessed with the I 2 test. The Cochrane risk of bias tool was used to assess the methodological quality of the selected studies. Nine randomized controlled trials involving 625 patients met the inclusion criteria. No significant improvement was found in bone mineral density (BMD) (SMD = -0.06, 95%CI= -0.22-0.11, p = 0.50); bone turnover markers (MD = -0.25, 95%CI= -0.54-0.03, p = 0.08); anthropometric parameters, including muscle mass, fat mass, body mass index (BMI), and weight (SMD = 0.02, 95%CI= -0.16-0.21, p = 0.81); or maximal isotonic knee extensor strength (SMD = 0.16, 95%CI= -0.63-0.95, p = 0.69). However, maximal isometric knee extensor strength improved (SMD = 0.71, 95%CI = 0.34-1.08, p = 0.0002). WBV is beneficial for enhancing maximal isometric knee extensor strength, but it has no overall treatment effect on BMD, bone turnover markers, anthropometric parameters, or maximal isotonic knee extensor strength in women with postmenopausal osteoporosis. Implication of rehabilitation Osteoporosis is the leading underlying cause of fractures in postmenopausal women, whole body vibration (WBV) has received much attention as a potential intervention for the management of osteoporosis in recent years. Whole body vibration is beneficial for enhancing maximal isometric knee extensor strength in women with postmenopausal osteoporosis. Whole body vibration has no overall treatment effect on bone mineral density, bone turnover markers, anthropometric parameters and maximal isotonic knee extensor strength in women with postmenopausal osteoporosis.

Mechanical torque measurement predicts load to implant cut-out: a biomechanical study investigating DHS anchorage in femoral heads.

PubMed

Suhm, Norbert; Hengg, Clemens; Schwyn, Ronald; Windolf, Markus; Quarz, Volker; Hänni, Markus

2007-08-01

Bone strength plays an important role in implant anchorage. Bone mineral density (BMD) is used as surrogate parameter to quantify bone strength and to predict implant anchorage. BMD can be measured by means of quantitative computer tomography (QCT) or dual energy X-ray absorptiometry (DXA). These noninvasive methods for BMD measurement are not available pre- or intra-operatively. Instead, the surgeon could determine bone strength by direct mechanical measurement. We have evaluated mechanical torque measurement for (A) its capability to quantify local bone strength and (B) its predictive value towards load at implant cut-out. Our experimental study was performed using sixteen paired human cadaver proximal femurs. BMD was determined for all specimens by QCT. The torque to breakaway of the cancellous bone structure (peak torque) was measured by means of a mechanical probe at the exact position of subsequent DHS placement. The fixation strength of the DHS achieved was assessed by cyclic loading in a stepwise protocol beginning with 1,500 N increasing 500 N every 5,000 cycles until 4,000 N. A highly significant correlation of peak torque with BMD (QCT) was found (r = 0.902, r (2) = 0.814, P < 0.001). Peak torque correlated highly significant with the load at implant cut-out (r = 0.795, P < 0.001). All specimens with a measured peak torque below 6.79 Nm failed at the first load level of 1,500 N. The specimens with a peak torque above 8.63 Nm survived until the last load level of 4,000 N. Mechanical peak torque measurement is able to quantify bone strength. In an experimental setup, peak torque identifies those specimens that are likely to fail at low load. In clinical routine, implant migration and cut-out depend on several parameters, which are difficult to control, such as fracture type, fracture reduction achieved, and implant position. The predictive value of peak torque towards cut-out in a clinical set-up therefore has to be carefully validated.

Rural versus nonrural differences in BMC, volumetric BMD, and bone size: a population-based cross-sectional study.

PubMed

Specker, Bonny; Binkley, Teresa; Fahrenwald, Nancy

2004-12-01

Despite reports of lower fracture risk among rural versus urban populations, few studies have investigated rural versus urban differences in bone mineral content (BMC) and bone mineral density (BMD). Population differences in cross-sectional bone geometry and understanding lifestyle factors responsible for these differences may reveal insights into the reason for differences in fracture risk. We hypothesized that if lifestyle differences in bone mass, size, and geometry are a result of muscle strength, activity, or dietary differences, Hutterite and rural populations should have greater bone mass compared to nonrural populations. The study population consisted of 1189 individuals: 504 rural Hutterites (188 men), 349 rural individuals (>75% life farming, 184 men), and 336 nonrural individuals (never lived on farm, 134 men) aged 20 to 66 years. BMC, bone area, and areal BMD (aBMD) of the total body (TB), hip, femoral neck (FN), and spine by DXA; volumetric BMD (vBMD) and bone geometry at the 4% and 20% radius; polar stress strain index (pSSI), a measure of bone strength, at the 20% pQCT site; and strength, 7-day activity recall, and 24-h diet recall were collected and compared among groups. Hutterite women and men had greater grip strength compared to rural and nonrural populations (both, P <0.001). Rural women had greater activity versus Hutterite and nonrural (P <0.001), while both Hutterite and rural men had greater activity than nonrural (P <0.001). Hutterite and rural populations tended to have greater BMC and areal size than the nonrural population, while Hutterites had greater BMC and areal size than rural population at some (TB, FN for females only), but not all (proximal hip), sites. Cortical vBMD was inversely associated with periosteal circumference at the 20% radius in women (r=-0.25, P <0.001) and men (r=-0.28, P <0.001) and was higher in nonrural versus Hutterite and rural men. Hutterite and rural women and men had greater pSSI at the 20% radius compared to nonrural; inclusion of strength measurements explained population differences among women, but not men. Lifestyle differences did not explain population differences in BMC, aBMD, vBMD, or bone size.

Three Dimensional Cancellous Bone Structure in Hypoparathyroidism

PubMed Central

Rubin, Mishaela R.; Dempster, David W.; Kohler, Thomas; Stauber, Martin; Zhou, Hua; Shane, Elizabeth; Nickolas, Thomas; Stein, Emily; Sliney, James; Silverberg, Shonni J.; Bilezikian, John P.; Müller, Ralph

2009-01-01

By conventional 2-dimensional histomorphometric analysis, we have shown that cancellous bone architecture is markedly altered in hypoparathyroidism. We have now extended these observations to a 3-dimensional analysis using microcomputed tomography. Percutaneous iliac crest bone biopsies were analyzed by high-resolution microcomputed tomography from the following 25 subjects with hypoparathyroidism: 5 postmenopausal women, 13 premenopausal women and 7 men. Thirteen living premenopausal healthy controls and 12 cadaver subjects without bone disease served as matched controls. Hypoparathyroid subjects had significantly greater bone surface density (BS/TV: 5.74 ± 4.7 vs. 3.73 ± 1.01 mm2/mm3 [mean ± SD]; p=0.04), trabecular thickness (Tb.Th: 0.25 ± 0.19 vs. 0.17 ± 0.04 mm; p=0.04), trabecular number (Tb.N: 2.99 ± 3.4 vs. 1.62 ± 0.39 mm−1; p=0.05) and connectivity density (Conn.D: 16.63 ± 18.7 vs. 8.39 ± 5.8 mm3; p=0.04) in comparison to matched controls. When an additional 8 hypoparathyorid (total n= 33) and 24 cadaver (total cadaver n= 36) subjects were added to the groups for an unmatched analysis, hypoparathyroid subjects had significantly greater cancellous bone volume (BV/TV: 26.98 ± 10 vs. 15.39 ± 4%; p< 0.001), , while trabecular separation (Tb.Sp: 0.642 ± 0.10 vs. 0.781 ± 0.13 mm; p<0.001) and estimation of the plate-rod characteristic (SMI: −0.457 ± 1.52 vs. 0.742 ± 0.51; p<0.001) were significantly lower, the latter observation implying a more plate-like trabecular structure. Variables of cancellous bone structure in the hypoparathyroid subjects, as assessed by microcomputed tomography, were highly correlated with those assessed by conventional histomorphometry. We conclude that cancellous bone in hypoparathyroidism is abnormal, suggesting that parathyroid hormone is required to maintain normal trabecular structure. The effect of these structural changes on bone strength remains to be determined. PMID:19782782

The effects of strength training and raloxifene on bone health in aging ovariectomized rats.

PubMed

Stringhetta-Garcia, Camila Tami; Singulani, Monique Patrício; Santos, Leandro Figueiredo; Louzada, Mário Jefferson Quirino; Nakamune, Ana Cláudia Stevanato; Chaves-Neto, Antonio Hernandes; Rossi, Ana Cláudia; Ervolino, Edilson; Dornelles, Rita Cássia Menegati

2016-04-01

The aim of this study was to investigate the effects of strength training (ST) and raloxifene (Ral), alone or in combination, on the prevention of bone loss in an aging estrogen-deficient rat model. Aging Wistar female rats were ovariectomized at 14months and allocated to four groups: (1) non-trained and treated with vehicle, NT-Veh; (2) strength training and treated with vehicle, ST-Veh; (3) non-trained and treated with raloxifene, NT-Ral; and (4) strength training and treated with raloxifene, ST-Ral. ST was performed on a ladder three times per week and Ral was administered daily by gavage (1mg/kg/day), both for 120days. Areal bone mineral density (aBMD), strength, microarchitecture, and biomarkers (osteocalcin, OCN; osteoprotegerin, OPG; and tartrate-resistant acid phosphatase, TRAP) were assessed. Immunohistochemistry was performed for runt-related transcription factor 2 (RUNX2), osterix (OSX), OCN, OPG, TRAP, and receptor activator of nuclear factor kappa-B ligand (RANKL). The rats that performed ST (ST-Veh) or were treated with Ral (NT-Ral) showed significant improvements in aBMD (p=0.001 and 0.004), bone strength (p=0.001), and bone microarchitecture, such as BV/TV (%) (p=0.001), BS/TV (mm(2)/mm(3)) (p=0.023 and 0.002), Conn.Dn (1/mm(3)) (p=0.001), Tb.N (1/mm) (p=0.012 and 0.011), Tb.Th (1/mm) (p=0.001), SMI (p=0.001 and 0.002), Tb.Sp (p=0.001), and DA (p=0.002 and 0.007); there was also a significant decrease in plasma levels of OCN (p=0.001 and 0.002) and OPG (p=0.003 and 0.014), compared with animals in the NT-Veh group. Ral, with or without ST, promoted an increased immunolabeling pattern for RUNX2 (p=0.0105 and p=0.0006) and OSX (p=0.0105), but a reduced immunolabeling pattern for TRAP (p=0.0056) and RANKL (p=0.033 and 0.004). ST increased the immunolabeling pattern for RUNX2 (p=0.0105), and association with Ral resulted in an increased immunolabeling pattern for OPG (p=0.0034) and OCN (p=0.0024). In summary, ST and Ral administration in aged, estrogen-deficient Wistar female rats is associated with a decrease in bone turnover marker plasma levels, increased activity of cells that promote osteoblastogenesis, and decreased activity of cells that promote osteoclastogenesis; these are correlated with higher aBMD, bone strength, and bone microarchitecture at the femoral neck. The results indicate that strength training and Ral are potential tools to reduce the risk of fractures at clinically relevant sites. Copyright © 2016 Elsevier Inc. All rights reserved.

Autogenous bone particle/titanium fiber composites for bone regeneration in a rabbit radius critical-size defect model.

PubMed

Xie, Huanxin; Ji, Ye; Tian, Qi; Wang, Xintao; Zhang, Nan; Zhang, Yicai; Xu, Jun; Wang, Nanxiang; Yan, Jinglong

2017-11-01

To explore the effects of autogenous bone particle/titanium fiber composites on repairing segmental bone defects in rabbits. A model of bilateral radial bone defect was established in 36 New Zealand white rabbits which were randomly divided into 3 groups according to filling materials used for bilaterally defect treatment: in group C, 9 animal bone defect areas were prepared into simple bilateral radius bone defect (empty sham) as the control group; 27 rabbits were used in groups ABP and ABP-Ti. In group ABP, left defects were simply implanted with autogenous bone particles; meanwhile, group ABP-Ti animals had right defects implanted with autogenous bone particle/titanium fiber composites. Animals were sacrificed at 4, 8, and 12 weeks, respectively, after operation. Micro-CT showed that group C could not complete bone regeneration. Bone volume to tissue volume values in group ABP-Ti were better than group ABP. From histology and histomorphometry Groups ABP and ABP-Ti achieved bone repair, the bone formation of group ABP-Ti was better. The mechanical strength of group ABP-Ti was superior to that of other groups. These results confirmed the effectiveness of autologous bone particle/titanium fiber composites for promoting bone regeneration and mechanical strength.

Symposium Introduction: Studies of women and men in bed and in space

NASA Astrophysics Data System (ADS)

Hargens, Alan

INTRODUCTION: Some gender differences in response to microgravity have been noted previously. Furthermore current exercise systems for space flight do not provide loads equal to those on Earth. We hypothesized that supine LBNP treadmill exercise combined with flywheel resistive exercise maintains upright physiologic responses and tissue mass following 30-days and 60-days of head-down tilt (HDT) bed rest (BR). METHODS: For WISE-2005, 16 healthy women (age 25-40 years) underwent a 20-day baseline period, followed by 60-days continuous HDT (-6 degrees) BR and then by recovery for an additional 20-days. Women were assigned to either a control group (CON, n=8) who performed no exercise or to an exercise group (EX, n=8). EX subjects performed a 40-min, variable intensity (40-80 RESULTS: For WISE-2005, post-BR orthostatic tolerance (time to pre-syncope) was signifi- cantly better in the EX group than that in the CON group (p¡ 0.05). On BR day 50, heart rate (HR) was elevated at supine rest for the CON, but not for EX. Moreover, during a supine LBNP stress test at 30 mmHg, the HR increase from Pre-BR to BR day 50 for the EX group was less than that for CON. Heart mass decreased significantly in CON, but increased signifi- cantly in EX. Post-BR upright VO2pk, muscle strength, and endurance decreased significantly in CON, but were preserved in EX. Post-BR bone resorption was greater than pre-BR in both groups. Helical peptide and N-telopeptide excretions increased in both CON and EX. However, bone-specific alkaline phosphatase, a bone formation marker, tended to be higher in EX than in CON. DISCUSSION AND CONCLUSIONS: Previously we found that orthostatic tolerance is lower in women than that in men. For WISE-2005, supine treadmill exercise protocol within LBNP along with flywheel resistive exercise maintains orthostatic responses, upright exercise capacity, heart mass, muscle strength and endurance during 60-days HDT BR. By comparison with previous studies, cardiac atrophy occurs similarly in women and men during HDT BR. Importantly, upright VO2pk is maintained for at least 5 days following the last LBNP exercise session, despite reduced session frequency (3-4 sessions/week compared to 6 sessions/week in earlier 30-day BR studies of identical twins). However, bone is less well-protected in WISE-2005 compared to our twins' protocol with LBNP exercise alone 6 days/week (without Flywheel resistive exercise). Overall these results help us understand gender differences with HDT BR and the efficacy of the combined-exercise countermeasure protocol during microgravity as simulated by 30- and 60-days of HDT BR. Supported by NASA, ESA, CSA, CNES; and by NASA Grants NAG9-1425 and NNJ04HF71G. We thank the UCSD-twin and WISE volunteers, UCSD GCRC staff, P Jost and MEDES staff.

[A study on alpha-tricalcium phosphate bone cement carbon fiber-reinforced].

PubMed

Wu, Wenjin; Yang, Weizhong; Zhou, Dali; Ma, Jiang; Xiao, Bin

2006-06-01

In order to improve the mechanical properties of alpha-tricalcium phosphate (alpha-TCP), we prepared surface-modified carbon fibers (CF) reinforced alpha-TCP composite bone cement. Bone cement was soaked in Ringer's body solution to test its capacity of fast formation of hydroxyapatite crystals and self-solidification. Scan electronic microscope (SEM) observation and compressive strength measurement were taken to analyze the mechanical properties and the micro- morphological structure of CF reinforced alpha-TCP bone cement. The results showed that the bone cement was transferred into hydroxyapatite plates after being soaked in Ringer's simulated body fluid for 5 days. Suitable amount of carbon fibers could well spread in and bond with the matrix of the bone cement. The mechanical properties of the bone cement have been improved by CF reinforcing; the compressive strength reaches 46.7 MPa when the amount of carbon fibers is 0.5% in weight percent, which is 22% higher than that of the non-reinforced alpha-TCP bone cement.

Appropriate Mechanochemical Conditions for Corrosion-Fatigue Testing of Magnesium Alloys for Temporary Bioimplant Applications

NASA Astrophysics Data System (ADS)

Harandi, Shervin Eslami; Singh Raman, R. K.

2015-05-01

Magnesium (Mg) alloys possess great potential as bioimplants. A temporary implant employed as support for the repair of a fractured bone must possess sufficient strength to maintain their mechanical integrity for the required duration of healing. However, Mg alloys are susceptible to sudden cracking or fracture under the simultaneous action of cyclic loading and the corrosive physiological environment, i.e., corrosion fatigue (CF). Investigations of such fracture should be performed under appropriate mechanochemical conditions that appropriately simulate the actual human body conditions. This article reviews the existing knowledge on CF of Mg alloys in simulated body fluid and describes a relatively more accurate testing procedure developed in the authors' laboratory.

Distinct characteristics of mandibular bone collagen relative to long bone collagen: relevance to clinical dentistry.

PubMed

Matsuura, Takashi; Tokutomi, Kentaro; Sasaki, Michiko; Katafuchi, Michitsuna; Mizumachi, Emiri; Sato, Hironobu

2014-01-01

Bone undergoes constant remodeling throughout life. The cellular and biochemical mechanisms of bone remodeling vary in a region-specific manner. There are a number of notable differences between the mandible and long bones, including developmental origin, osteogenic potential of mesenchymal stem cells, and the rate of bone turnover. Collagen, the most abundant matrix protein in bone, is responsible for determining the relative strength of particular bones. Posttranslational modifications of collagen, such as intermolecular crosslinking and lysine hydroxylation, are the most essential determinants of bone strength, although the amount of collagen is also important. In comparison to long bones, the mandible has greater collagen content, a lower amount of mature crosslinks, and a lower extent of lysine hydroxylation. The great abundance of immature crosslinks in mandibular collagen suggests that there is a lower rate of cross-link maturation. This means that mandibular collagen is relatively immature and thus more readily undergoes degradation and turnover. The greater rate of remodeling in mandibular collagen likely renders more flexibility to the bone and leaves it more suited to constant exercise. As reviewed here, it is important in clinical dentistry to understand the distinctive features of the bones of the jaw.

Distinct Characteristics of Mandibular Bone Collagen Relative to Long Bone Collagen: Relevance to Clinical Dentistry

PubMed Central

Tokutomi, Kentaro; Sasaki, Michiko; Katafuchi, Michitsuna; Mizumachi, Emiri; Sato, Hironobu

2014-01-01

Bone undergoes constant remodeling throughout life. The cellular and biochemical mechanisms of bone remodeling vary in a region-specific manner. There are a number of notable differences between the mandible and long bones, including developmental origin, osteogenic potential of mesenchymal stem cells, and the rate of bone turnover. Collagen, the most abundant matrix protein in bone, is responsible for determining the relative strength of particular bones. Posttranslational modifications of collagen, such as intermolecular crosslinking and lysine hydroxylation, are the most essential determinants of bone strength, although the amount of collagen is also important. In comparison to long bones, the mandible has greater collagen content, a lower amount of mature crosslinks, and a lower extent of lysine hydroxylation. The great abundance of immature crosslinks in mandibular collagen suggests that there is a lower rate of cross-link maturation. This means that mandibular collagen is relatively immature and thus more readily undergoes degradation and turnover. The greater rate of remodeling in mandibular collagen likely renders more flexibility to the bone and leaves it more suited to constant exercise. As reviewed here, it is important in clinical dentistry to understand the distinctive features of the bones of the jaw. PMID:24818151

Improvement of the compressive strength of a cuttlefish bone-derived porous hydroxyapatite scaffold via polycaprolactone coating.

PubMed

Kim, Beom-Su; Kang, Hyo Jin; Lee, Jun

2013-10-01

Cuttlefish bones (CBs) have emerged as attractive biomaterials because of their porous structure and components that can be converted into hydroxyapatite (HAp) via a hydrothermal reaction. However, their brittleness and low strength restrict their application in bone tissue engineering. Therefore, to improve the compressive strength of the scaffold following hydrothermal conversion to a HAp form of CB (CB-HAp), the scaffold was coated using a polycaprolactone (PCL) polymer at various concentrations. In this study, raw CB was successfully converted into HAp via a hydrothermal reaction. We then evaluated their surface properties and composition by scanning electron microscopy and X-ray diffraction analysis. The CB-HAp coated with PCL showed improved compressive performance and retained a microporous structure. The compressive strength was significantly increased upon coating with 5 and 10% PCL, by 2.09- and 3.30-fold, respectively, as compared with uncoated CB-HAp. However, coating with 10% PCL resulted in a reduction in porosity. Furthermore, an in vitro biological evaluation demonstrated that MG-63 cells adhered well, proliferated and were able to be differentiated on the PCL-coated CB-HAp scaffold, which was noncytotoxic. These results suggest that a simple coating method is useful to improve the compressive strength of CB-HAp for bone tissue engineering applications. Copyright © 2013 Wiley Periodicals, Inc.

Elevated Levels of Peripheral Kynurenine Decrease Bone Strength in Rats with Chronic Kidney Disease

PubMed Central

Kalaska, Bartlomiej; Pawlak, Krystyna; Domaniewski, Tomasz; Oksztulska-Kolanek, Ewa; Znorko, Beata; Roszczenko, Alicja; Rogalska, Joanna; Brzoska, Malgorzata M.; Lipowicz, Pawel; Doroszko, Michal; Pryczynicz, Anna; Pawlak, Dariusz

2017-01-01

The diagnosis and treatment of bone disorders in patients with chronic kidney disease (CKD) represent a clinical challenge. CKD leads to mineral and bone complications starting early in the course of renal failure. Recently, we have observed the positive relationship between intensified central kynurenine turnover and bone strength in rats with subtotal 5/6 nephrectomy (5/6 Nx)-induced CKD. The aim of the present study was to determine the association between peripheral kynurenine pathway metabolites and bone strength in rats with 5/6 Nx-induced CKD. The animals were sacrificed 1 and 3 months after 5/6 Nx or sham operation. Nephrectomized rats presented higher concentrations of serum creatinine, urea nitrogen, and parathyroid hormone both 1 and 3 months after nephrectomy. These animals revealed higher concentrations of kynurenine and 3-hydroxykynurenine in the serum and higher gene expression of aryl hydrocarbon receptor (AhR) as a physiological receptor for kynurenine and AhR-dependent cytochrome in the bone tissue. Furthermore, nephrectomy significantly increased the number of osteoclasts in the bone without affecting their resorptive activity measured in serum. These changes were particularly evident in rats 1 month after 5/6 Nx. The main bone biomechanical parameters of the tibia were unchanged between nephrectomized and sham-operated rats but were significantly increased in older compared to younger animals. A similar trend was observed for geometrical parameters measured with calipers, bone mineral density based on Archimedes' method and image of bone microarchitecture obtained from micro-computed tomography analyses of tibial cortical bone. In nephrectomized animals, peripheral kynurenine levels correlated negatively with the main parameters of bone biomechanics, bone geometry, and bone mineral density values. In conclusion, our data suggest that CKD-induced elevated levels of peripheral kynurenine cause pathological changes in bone structure via AhR pathway. This finding opens new opportunities for the treatment/prevention of osteoporosis in CKD. PMID:29163188

High Resolution Peripheral Quantitative Computed Tomography for Assessment of Bone Quality

NASA Astrophysics Data System (ADS)

Kazakia, Galateia

2014-03-01

The study of bone quality is motivated by the high morbidity, mortality, and societal cost of skeletal fractures. Over 10 million people are diagnosed with osteoporosis in the US alone, suffering 1.5 million osteoporotic fractures and costing the health care system over 17 billion annually. Accurate assessment of fracture risk is necessary to ensure that pharmacological and other interventions are appropriately administered. Currently, areal bone mineral density (aBMD) based on 2D dual-energy X-ray absorptiometry (DXA) is used to determine osteoporotic status and predict fracture risk. Though aBMD is a significant predictor of fracture risk, it does not completely explain bone strength or fracture incidence. The major limitation of aBMD is the lack of 3D information, which is necessary to distinguish between cortical and trabecular bone and to quantify bone geometry and microarchitecture. High resolution peripheral quantitative computed tomography (HR-pQCT) enables in vivo assessment of volumetric BMD within specific bone compartments as well as quantification of geometric and microarchitectural measures of bone quality. HR-pQCT studies have documented that trabecular bone microstructure alterations are associated with fracture risk independent of aBMD.... Cortical bone microstructure - specifically porosity - is a major determinant of strength, stiffness, and fracture toughness of cortical tissue and may further explain the aBMD-independent effect of age on bone fragility and fracture risk. The application of finite element analysis (FEA) to HR-pQCT data permits estimation of patient-specific bone strength, shown to be associated with fracture incidence independent of aBMD. This talk will describe the HR-pQCT scanner, established metrics of bone quality derived from HR-pQCT data, and novel analyses of bone quality currently in development. Cross-sectional and longitudinal HR-pQCT studies investigating the impact of aging, disease, injury, gender, race, and therapeutics on bone quality will be discussed.

The effect of topiramate and lamotrigine on rat bone mass, structure and metabolism.

PubMed

Simko, Julius; Fekete, Sona; Gradosova, Iveta; Malakova, Jana; Zivna, Helena; Valis, Martin; Palicka, Vladimir; Zivny, Pavel

2014-05-15

There is only limited data concerning the effect of the newer antiepileptic drugs on bone. The objective of this study was to determine the effect of topiramate (TPM) and lamotrigine (LTG) monotherapy on bone mineral density (BMD), mineral content (BMC), bone markers, body composition and bone mechanical strength in the orchidectomized (ORX) rat model. 24 orchidectomized Wistar rats were divided into control and test groups, 8 rats in each group. The control rats received standard laboratory diet (SLD) while rats in the test group were fed with SLD enriched with LTG or TPM for 12 weeks. Dual energy X-ray absorptiometry was used to measure bone mineral density. The concentrations of bone metabolism markers were assayed in bone homogenate. In addition, both femurs were measured and used for biomechanical testing. Compared to the control group, both test groups had significantly lower weight, fat mass, whole body and femur BMD, BMC and reduced mechanical strength of bone. All of these changes were more pronounced in rats exposed to LTG. In conclusion, both LTG and TPM significantly reduce BMD and body weight and impair mechanical strength of bone. A question arises as to the degree of dependence of the effect on the dose. Further studies are warranted to establish whether LTG and TPM may have a clinically significant effect on BMD exclusively in the model of gonadectomized rats, or whether the effect applies also in the model of gonadally intact animals, and in the respective human models. Copyright © 2014 Elsevier B.V. All rights reserved.

Enhanced Wnt signaling improves bone mass and strength, but not brittleness, in the Col1a1(+/mov13) mouse model of type I Osteogenesis Imperfecta.

PubMed

Jacobsen, Christina M; Schwartz, Marissa A; Roberts, Heather J; Lim, Kyung-Eun; Spevak, Lyudmila; Boskey, Adele L; Zurakowski, David; Robling, Alexander G; Warman, Matthew L

2016-09-01

Osteogenesis Imperfecta (OI) comprises a group of genetic skeletal fragility disorders. The mildest form of OI, Osteogenesis Imperfecta type I, is frequently caused by haploinsufficiency mutations in COL1A1, the gene encoding the α1(I) chain of type 1 collagen. Children with OI type I have a 95-fold higher fracture rate compared to unaffected children. Therapies for OI type I in the pediatric population are limited to anti-catabolic agents. In adults with osteoporosis, anabolic therapies that enhance Wnt signaling in bone improve bone mass, and ongoing clinical trials are determining if these therapies also reduce fracture risk. We performed a proof-of-principle experiment in mice to determine whether enhancing Wnt signaling in bone could benefit children with OI type I. We crossed a mouse model of OI type I (Col1a1(+/Mov13)) with a high bone mass (HBM) mouse (Lrp5(+/p.A214V)) that has increased bone strength from enhanced Wnt signaling. Offspring that inherited the OI and HBM alleles had higher bone mass and strength than mice that inherited the OI allele alone. However, OI+HBM and OI mice still had bones with lower ductility compared to wild-type mice. We conclude that enhancing Wnt signaling does not make OI bone normal, but does improve bone properties that could reduce fracture risk. Therefore, agents that enhance Wnt signaling are likely to benefit children and adults with OI type 1. Copyright © 2016 Elsevier Inc. All rights reserved.

Osteoporosis and body composition.

PubMed

Crepaldi, G; Romanato, G; Tonin, P; Maggi, S

2007-01-01

The Epidemiologic Study on the Prevalence of Osteoporosis in Italy showed that the prevalence of osteoporosis among women and men aged 60 yr and over is 22.8% and 14.5%, respectively, giving rise to about 80,000 new fractures a yr. Sarcopenia is considered to be one of the main features of the aging process. It is characterized by a reduction in muscle mass and muscle strength, and affects women more than men. It is associated with a increased risk of fractures consequent upon a greater predisposition to falls, but also to the lack of bone remodeling due to reduced muscle mechanical strength. Muscle strength determines quality bone modifications such as density, strength, and microarchitecture. Variations in the ratios of cortical and muscle areas give rise to various types of osteoporosis, with different risks of fracture. Bone mineral density increases with body fat mass, and obesity has a protective effect against osteoporosis. This protective effect is explained by a combination of hormonal (peripheral aromatization of androgens to estrogens in adipose tissue) and mechanical factors (on weight-bearing bone sites), but the hormone leptin also probably mediates fat and bone mass. Serum leptin levels are closely related to body fat mass, and some findings suggest the peripheral effect of leptin, which exerts estrogenic effects, enhancing osteoblastic differentiation and inhibiting late adipocytic differentiation. The overall effect of leptin on bone results from a balance between negative central effects and positive direct peripheral effects, according to serum leptin levels.

Longitudinal relationships between whole body and central adiposity on weight-bearing bone geometry, density, and bone strength: a pQCT study in young girls

PubMed Central

Farr, Joshua N.; Laudermilk, Monica J.; Lee, Vinson R.; Blew, Robert M.; Stump, Craig; Houtkooper, Linda; Lohman, Timothy G.; Going, Scott B.

2015-01-01

Summary Longitudinal relationships between adiposity (total body and central) and bone development were assessed in young girls. Total body and android fat masses were positively associated with bone strength and density parameters of the femur and tibia. These results suggest adiposity may have site-specific stimulating effects on the developing bone. Introduction Childhood obesity may impair bone development, but the relationships between adiposity and bone remain unclear. Failure to account for fat pattern may explain the conflicting results. Purpose Longitudinal associations of total body fat mass (TBFM) and android fat mass (AFM) with 2-year changes in weight-bearing bone parameters were examined in 260 girls aged 8–13 years at baseline. Peripheral quantitative computed tomography was used to measure bone strength index (BSI, square milligrams per quartic millimeter), strength–strain index (SSI, cubic millimeters), and volumetric bone mineral density (vBMD, milligrams per cubic centimeter) at distal metaphyseal and diaphyseal regions of the femur and tibia. TBFM and AFM were assessed by dual-energy x-ray absorptiometry. Results Baseline TBFM and AFM were positively associated with the change in femur BSI (r =0.20, r =0.17, respectively) and femur trabecular vBMD (r =0.19, r =0.19, respectively). Similarly, positive associations were found between TBFM and change in tibia BSI and SSI (r =0.16, r =0.15, respectively), and femur total and trabecular vBMD (r =0.12, r =0.14, respectively). Analysis of covariance showed that girls in the middle thirds of AFM had significantly lower femur trabecular vBMD and significantly higher tibia cortical vBMD than girls in the highest thirds of AFM. All results were significant at p <0.05. Conclusions Whereas baseline levels of TBFM and AFM are positive predictors of bone strength and density at the femur and tibia, higher levels of AFM above a certain level may impair cortical vBMD growth at weight-bearing sites. Future studies in obese children will be needed to test this possibility. NIH/NICHD #HD-050775. PMID:24113839

Associations of muscle force, power, cross-sectional muscle area and bone geometry in older UK men.

PubMed

Zengin, Ayse; Pye, Stephen R; Cook, Michael J; Adams, Judith E; Rawer, Rainer; Wu, Frederick C W; O'Neill, Terence W; Ward, Kate A

2017-08-01

Ageing is associated with sarcopenia, osteoporosis, and increased fall risk, all of which contribute to increased fracture risk. Mechanically, bone strength adapts in response to forces created by muscle contractions. Adaptations can be through changes in bone size, geometry, and bending strength. Muscle mass is often used as a surrogate for muscle force; however, force can be increased without changes in muscle mass. Increased fall risk with ageing has been associated with a decline in muscle power-which is a measure of mobility. The aims of this study were as follows: (i) to investigate the relationship between muscle parameters in the upper and lower limbs with age in UK men and the influence of ethnicity on these relationships; (ii) to examine the relationships between jump force/grip strength/cross-sectional muscle area (CSMA) with bone outcomes at the radius and tibia. White European, Black Afro-Caribbean, and South Asian men aged 40-79 years were recruited from Manchester, UK. Cortical bone mineral content, cross-sectional area, cortical area, cross-sectional moment of inertia, and CSMA were measured at the diaphysis of the radius and tibia using peripheral quantitative computed tomography. Lower limb jump force and power were measured from a single two-legged jump performed on a ground-reaction force platform. Grip strength was measured using a dynamometer. Associations between muscle and bone outcomes was determined using linear regression with adjustments for age, height, weight, and ethnicity. Three hundred and one men were recruited. Jump force was negatively associated with age; for every 10 year increase in age, there was a 4% reduction in jump force (P < 0.0001). There was a significant age-ethnicity interaction for jump power (P = 0.039); after adjustments, this was attenuated (P = 0.088). For every 10 year increase in age, grip strength decreased by 11%. Jump force was positively associated with tibial bone outcomes: a 1 standard deviation greater jump force was associated with significantly higher cortical bone mineral content 3.1%, cross-sectional area 4.2%, cortical area 3.4%, and cross-sectional moment of inertia 6.8% (all P < 0.001). Cross-sectional muscle area of the lower leg was not associated with tibial bone outcomes. Both grip strength and CSMA of the arm were positively associated, to a similar extent, with radius diaphyseal bone outcomes. Jump force and power are negatively associated with age in UK men. In the lower limb, the measurement of jump force is more strongly related to bone outcomes than CSMA. It is important to consider jump force and power when understanding the aetiology of bone loss and mobility in ageing men. © 2017 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of the Society on Sarcopenia, Cachexia and Wasting Disorders.

Graphite-reinforced bone cement

NASA Technical Reports Server (NTRS)

Knoell, A. C.

1976-01-01

Chopped graphite fibers added to surgical bone cement form bonding agent with mechanical properties closely matched to those of bone. Curing reaction produces less heat, resulting in reduced traumatization of body tissues. Stiffness is increased without affecting flexural strength.

Limited Associations between Keel Bone Damage and Bone Properties Measured with Computer Tomography, Three-Point Bending Test, and Analysis of Minerals in Swiss Laying Hens

PubMed Central

Gebhardt-Henrich, Sabine G.; Pfulg, Andreas; Fröhlich, Ernst K. F.; Käppeli, Susanna; Guggisberg, Dominik; Liesegang, Annette; Stoffel, Michael H.

2017-01-01

Keel bone damage is a wide-spread welfare problem in laying hens. It is unclear so far whether bone quality relates to keel bone damage. The goal of the present study was to detect possible associations between keel bone damage and bone properties of intact and damaged keel bones and of tibias in end-of-lay hens raised in loose housing systems. Bones were palpated and examined by peripheral quantitative computer tomography (PQCT), a three-point bending test, and analyses of bone ash. Contrary to our expectations, PQCT revealed higher cortical and trabecular contents in fractured than in intact keel bones. This might be due to structural bone repair after fractures. Density measurements of cortical and trabecular tissues of keel bones did not differ between individuals with and without fractures. In the three-point bending test of the tibias, ultimate shear strength was significantly higher in birds with intact vs. fractured keel bones. Likewise, birds with intact or slightly deviated keel bones had higher mineral and calcium contents of the keel bone than birds with fractured keel bones. Calcium content in keel bones was correlated with calcium content in tibias. Although there were some associations between bone traits related to bone strength and keel bone damage, other factors such as stochastic events related to housing such as falls and collisions seem to be at least as important for the prevalence of keel bone damage. PMID:28848740

A new adhesive technique for internal fixation in midfacial surgery

PubMed Central

Endres, Kira; Marx, Rudolf; Tinschert, Joachim; Wirtz, Dieter Christian; Stoll, Christian; Riediger, Dieter; Smeets, Ralf

2008-01-01

Background The current surgical therapy of midfacial fractures involves internal fixation in which bone fragments are fixed in their anatomical positions with osteosynthesis plates and corresponding screws until bone healing is complete. This often causes new fractures to fragile bones while drilling pilot holes or trying to insert screws. The adhesive fixation of osteosynthesis plates using PMMA bone cement could offer a viable alternative for fixing the plates without screws. In order to achieve the adhesive bonding of bone cement to cortical bone in the viscerocranium, an amphiphilic bone bonding agent was created, analogous to the dentin bonding agents currently on the market. Methods The adhesive bonding strengths were measured using tension tests. For this, metal plates with 2.0 mm diameter screw holes were cemented with PMMA bone cement to cortical bovine bone samples from the femur diaphysis. The bone was conditioned with an amphiphilic bone bonding agent prior to cementing. The samples were stored for 1 to 42 days at 37 degrees C, either moist or completely submerged in an isotonic NaCl-solution, and then subjected to the tension tests. Results Without the bone bonding agent, the bonding strength was close to zero (0.2 MPa). Primary stability with bone bonding agent is considered to be at ca. 8 MPa. Moist storage over 42 days resulted in decreased adhesion forces of ca. 6 MPa. Wet storage resulted in relatively constant bonding strengths of ca. 8 MPa. Conclusion A new amphiphilic bone bonding agent was developed, which builds an optimizied interlayer between the hydrophilic bone surface and the hydrophobic PMMA bone cement and thus leads to adhesive bonding between them. Our in vitro investigations demonstrated the adhesive bonding of PMMA bone cement to cortical bone, which was also stable against hydrolysis. The newly developed adhesive fixing technique could be applied clinically when the fixation of osteosynthesis plates with screws is impossible. With the detected adhesion forces of ca. 6 to 8 MPa, it is assumed that the adhesive fixation system is able to secure bone fragments from the non-load bearing midfacial regions in their orthotopic positions until fracture consolidation is complete. PMID:18489785

Skeletal Geometry and Indices of Bone Strength in Artistic Gymnasts

PubMed Central

Dowthwaite, Jodi N.; Scerpella, Tamara A.

2010-01-01

This review addresses bone geometry and indices of skeletal strength associated with exposure to gymnastic loading during growth. A brief background characterizes artistic gymnastics as a mechanical loading model and outlines densitometric techniques, skeletal outcomes and challenges in assessment of skeletal adaptation. The literature on bone geometric adaptation to gymnastic loading is sparse and consists of results for disparate skeletal sites, maturity phases, gender compositions and assessment methods, complicating synthesis of an overriding view. Furthermore, most studies assess only females, with little information on males and adults. Nonetheless, gymnastic loading during growth appears to yield significant enlargement of total and cortical bone geometry (+10 to 30%) and elevation of trabecular density (+20%) in the forearm, yielding elevated indices of skeletal strength (+20 to +50%). Other sites exhibit more moderate geometric and densitometric adaptations (5 to 15%). Mode of adaptation appears to be site-specific; some sites demonstrate marked periosteal and endosteal expansion, whereas other sites exhibit negligible or moderate periosteal expansion coupled with endocortical contraction. Further research is necessary to address sex-, maturity- and bone tissue-specific adaptation, as well as maintenance of benefits beyond loading cessation. PMID:19949278

Fiber-enriched double-setting calcium phosphate bone cement.

PubMed

dos Santos, Luís Alberto; Carrodéguas, Raúl Garcia; Boschi, Anselmo Ortega; Fonseca de Arruda, Antônio Celso

2003-05-01

Calcium phosphate bone cements are useful in orthopedics and traumatology, their main advantages being their biocompatibility and bioactivity, which render bone tissue osteoconductive, providing in situ hardening and easy handling. However, their low mechanical strength, which, in the best of cases, is equal to the trabecular bone, and their very low toughness are disadvantages. Calcium phosphate cement compositions with mechanical properties more closely resembling those of human bone would broaden the range of applications, which is currently limited to sites subjected to low loads. This study investigated the influence of added polypropylene, nylon, and carbon fibers on the mechanical properties of double setting alpha-tricalcium phosphate-based cement, using calcium phosphate cement added to an in situ polymerizable acrylamide-based system recently developed by the authors. Although the addition of fibers was found to reduce the compression strength of the double-setting calcium phosphate cement because of increased porosity, it strongly increased the cement's toughness (J(IC)) and tensile strength. The composites developed in this work, therefore, have a potential application in shapes subjected to flexure. Copyright 2003 Wiley Periodicals, Inc.

Endogenous hormones, muscle strength, and risk of fall-related fractures in older women.

PubMed

Sipilä, Sarianna; Heikkinen, Eino; Cheng, Sulin; Suominen, Harri; Saari, Päivi; Kovanen, Vuokko; Alén, Markku; Rantanen, Taina

2006-01-01

Among older people, fracture-causing fall often leads to health deterioration. The role of endogenous hormone status and muscle strength on fall-related fracture risk is unclear. This study investigates if, after adjustment for bone density, endogenous hormones and muscle strength would predict fall-related limb fracture incidence in older community-dwelling women followed-up over 10 years. As a part of a prospective population-based study, 187 75-year-old women were investigated. Serum estradiol, testosterone, sex hormone binding globulin, and dehydroepiandrosterone sulfate concentrations were analyzed, and isometric muscle strength and bone mineral density were assessed. Fall-related limb fractures were gathered from patient records. Serum estradiol concentration was a significant predictor of fall-related limb fractures. Women with serum estradiol concentrations less than 0.022 nmol/L had a 3-fold risk (relative risk 3.05; 95% confidence interval, 1.26-7.36), and women with estradiol concentrations between 0.022 and 0.066 nmol/L doubled the risk (relative risk 2.24; 95% confidence interval, 0.97-5.19) of fall-related limb fracture compared to the women with estradiol concentrations ()above 0.066 nmol/L. Adjustment for muscle strength and bone mineral density did not materially change the risk estimates. High muscle strength was associated with a low incidence of fall-related limb fractures. This study showed that in 75-year-old women higher serum estradiol concentration and greater muscle strength were independently associated with a low incidence of fall-related limb fractures even after adjustment for bone density. Our results suggest that hormonal status and muscle strength have their own separate mechanisms protecting from fall-related fractures. This finding is of importance in developing preventive strategies, but calls for further study.

Factors associated with appendicular bone mass in older women. The Study of Osteoporotic Fractures Research Group.

PubMed

Bauer, D C; Browner, W S; Cauley, J A; Orwoll, E S; Scott, J C; Black, D M; Tao, J L; Cummings, S R

1993-05-01

To determine the factors associated with appendicular bone mass in older women. Cross-sectional analysis of baseline data collected for a multicenter, prospective study of osteoporotic fractures. Four clinical centers in Baltimore, Maryland; Minneapolis, Minnesota; Portland, Oregon; and the Monongahela valley, Pennsylvania. A total of 9704 ambulatory, nonblack women, ages 65 years or older, recruited from population-based listings. Demographic and historical information and anthropometric measurements were obtained from a baseline questionnaire, interview, and examination. Single-photon absorptiometry scans were obtained at three sites: the distal radius, midradius, and calcaneus. Multivariate associations with bone mass were first examined in a randomly selected half of the cohort (training group) and were then tested on the other half of the cohort (validation group). In order of decreasing strength of association, estrogen use, non-insulin-dependent diabetes, thiazide use, increased weight, greater muscle strength, later age at menopause, and greater height were independently associated with higher bone mass. Gastric surgery, age, history of maternal fracture, smoking, and caffeine intake were associated with lower bone mass (all P < 0.05). For example, we found that 2 or more years of estrogen use was associated with a 7.2% increase in distal radius bone mass, whereas gastrectomy was associated with an 8.2% decrease in bone mass. The associations between bone mass and dietary calcium intake and rheumatoid arthritis were inconsistent. Alcohol use, physical activity, use of calcium supplements, pregnancy, breast-feeding, parental nationality, and hair color were among the many variables not associated with bone mass. Multivariate models accounted for 20% to 35% of the total variance of bone mass. A large number of factors influence the bone mass of elderly women; however, age, weight, muscle strength, and estrogen use are the most important factors.

Pullout strength of cancellous screws in human femoral heads depends on applied insertion torque, trabecular bone microarchitecture and areal bone mineral density.

PubMed

Ab-Lazid, Rosidah; Perilli, Egon; Ryan, Melissa K; Costi, John J; Reynolds, Karen J

2014-12-01

For cancellous bone screws, the respective roles of the applied insertion torque (TInsert) and of the quality of the host bone (microarchitecture, areal bone mineral density (aBMD)), in contributing to the mechanical holding strength of the bone-screw construct (FPullout), are still unclear. During orthopaedic surgery screws are tightened, typically manually, until adequate compression is attained, depending on surgeons' manual feel. This corresponds to a subjective insertion torque control, and can lead to variable levels of tightening, including screw stripping. The aim of this study, performed on cancellous screws inserted in human femoral heads, was to investigate which, among the measurements of aBMD, bone microarchitecture, and the applied TInsert, has the strongest correlation with FPullout. Forty six femoral heads were obtained, over which microarchitecture and aBMD were evaluated using micro-computed tomography and dual X-ray absorptiometry. Using an automated micro-mechanical test device, a cancellous screw was inserted in the femoral heads at TInsert set to 55% to 99% of the predicted stripping torque beyond screw head contact, after which FPullout was measured. FPullout exhibited strongest correlations with TInsert (R=0.88, p<0.001), followed by structure model index (SMI, R=-0.81, p<0.001), bone volume fraction (BV/TV, R=0.73, p<0.001) and aBMD (R=0.66, p<0.01). Combinations of TInsert with microarchitectural parameters and/or aBMD did not improve the prediction of FPullout. These results indicate that, for cancellous screws, FPullout depends most strongly on the applied TInsert, followed by microarchitecture and aBMD of the host bone. In trabecular bone, screw tightening increases the holding strength of the screw-bone construct. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of deletion of ER-alpha in osteoblast-lineage cells on bone mass and adaptation to mechanical loading differs in female and male mice

PubMed Central

Melville, Katherine M.; Kelly, Natalie H.; Surita, Gina; Buchalter, Daniel B.; Schimenti, John C.; Main, Russell P.; Ross, F. Patrick; van der Meulen, Marjolein C. H.

2015-01-01

Estrogen receptor alpha (ERα) has been implicated in bone’s response to mechanical loading in both males and females. ERα in osteoblast lineage cells is important for determining bone mass, but results depend on animal sex and the cellular stage at which ERα is deleted. We demonstrated previously that when ERα is deleted from mature osteoblasts and osteocytes in mixed background female mice, bone mass and strength are decreased. However, few studies exist examining the skeletal response to loading in bone cell-specific ERαKO mice. Therefore, we crossed ERα floxed (ERαfl/fl) and osteocalcin-Cre (OC-Cre) mice to generate animals lacking ERα in mature osteoblasts and osteocytes (pOC-ERαKO) and littermate controls (LC). At 10 weeks of age the left tibia was loaded in vivo for two weeks. We analyzed bone mass through microCT, bone formation rate by dynamic histomorphometry, bone strength from mechanical testing, and osteoblast and osteoclast activity by serum chemistry and immunohistochemistry. ERα in mature osteoblasts differentially regulated bone mass in males and females. Compared to LC, female pOC-ERαKO mice had decreased cortical and cancellous bone mass, while male pOC-ERαKO mice had equal or greater bone mass than LC. Bone mass results correlated with decreased compressive strength in pOC-ERαKO female L5 vertebrae, and with increased maximum moment in pOC-ERαKO male femora. Female pOC-ERαKO mice responded more to mechanical loading, while the response of pOC-ERαKO male animals was similar to their littermate controls. PMID:25707500

[Comparative studies on the material performances of natural bone-like apatite from different bone sources].

PubMed

Fan, Xiaoxia; Ren, Haohao; Chen, Shutian; Wang, Guangni; Deng, Tianyu; Chen, Xingtao; Yan, Yonggang

2014-04-01

The compressive strength of the original bone tissue was tested, based on the raw human thigh bone, bovine bone, pig bone and goat bone. The four different bone-like apatites were prepared by calcining the raw bones at 800 degrees C for 8 hours to remove organic components. The comparison of composition and structure of bone-like apatite from different bone sources was carried out with a composition and structure test. The results indicated that the compressive strength of goat bone was similar to that of human thigh bone, reached (135.00 +/- 7.84) MPa; Infrared spectrum (IR), X-ray diffraction (XRD) analysis results showed that the bone-like apatite from goat bone was much closer to the structure and phase composition of bone-like apatite of human bones. Inductively Coupled Plasma (ICP) test results showed that the content of trace elements of bone-like apatite from goat bone was closer to that of apatite of human bone. Energy Dispersive Spectrometer (EDS) results showed that the Ca/P value of bone-like apatite from goat bone was also close to that of human bone, ranged to 1.73 +/- 0.033. Scanning electron microscopy (SEM) patterns indicated that the macrographs of the apatite from human bone and that of goat bone were much similar to each other. Considering all the results above, it could be concluded that the goat bone-like apatite is much similar to that of human bone. It can be used as a potential natural bioceramic material in terms of material properties.

Site-specific, adult bone benefits attributed to loading during youth: A preliminary longitudinal analysis.

PubMed

Scerpella, Tamara A; Bernardoni, Brittney; Wang, Sijian; Rathouz, Paul J; Li, Quefeng; Dowthwaite, Jodi N

2016-04-01

We examined site-specific bone development in relation to childhood and adolescent artistic gymnastics exposure, comparing up to 10years of prospectively acquired longitudinal data in 44 subjects, including 31 non-gymnasts (NON) and 13 gymnasts (GYM) who participated in gymnastics from pre-menarche to ≥1.9years post-menarche. Subjects underwent annual regional and whole-body DXA scans; indices of bone geometry and strength were calculated. Anthropometrics, physical activity, and maturity were assessed annually, coincident with DXA scans. Non-linear mixed effect models centered growth in bone outcomes at menarche and adjusted for menarcheal age, height, and non-bone fat-free mass to evaluate GYM-NON differences. A POST-QUIT variable assessed the withdrawal effect of quitting gymnastics. Curves for bone area, mass (BMC), and strength indices were higher in GYM than NON at both distal radius metaphysis and diaphysis (p<0.0001). At the femoral neck, greater GYM BMC (p<0.01), narrower GYM endosteal diameter (p<0.02), and similar periosteal width (p=0.09) yielded GYM advantages in narrow neck cortical thickness and buckling ratio (both p<0.001; lower BR indicates lower fracture risk). Lumbar spine and sub-head BMC were greater in GYM than NON (p<0.036). Following gymnastics cessation, GYM slopes increased for distal radius diaphysis parameters (p≤0.01) and for narrow neck BR (p=0.02). At the distal radius metaphysis, GYM BMC and compressive strength slopes decreased, as did slopes for lumbar spine BMC, femoral neck BMC, and narrow neck cortical thickness (p<0.02). In conclusion, advantages in bone mass, geometry, and strength at multiple skeletal sites were noted across growth and into young adulthood in girls who participated in gymnastics loading to at least 1.9years post-menarche. Following gymnastics cessation, advantages at cortical bone sites improved or stabilized, while advantages at corticocancellous sites stabilized or diminished. Additional longitudinal observation is necessary to determine whether residual loading benefits enhance lifelong skeletal strength. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of losartan treatment on the physicochemical properties of diabetic rat bone.

PubMed

Donmez, Baris Ozgur; Unal, Mustafa; Ozdemir, Semir; Ozturk, Nihal; Oguz, Nurettin; Akkus, Ozan

2017-03-01

Inhibitors of the renin-angiotensin system used to treat several diseases have also been shown to be effective on bone tissue, suggesting that angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may reduce fracture risk. The present study investigated the effects of losartan on the physicochemical and biomechanical properties of diabetic rat bone. Losartan (5 mg/kg/day) was administered via oral gavage for 12 weeks. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry. Whole femurs were tested under tension to evaluate the biomechanical properties of bone. The physicochemical properties of bone were analyzed by Fourier transform infrared spectroscopy. Although losartan did not recover decreases in the BMD of diabetic bone, it recovered the physicochemical (mineral and collagen matrix) properties of diabetic rat bone. Furthermore, losartan also recovered ultimate tensile strength of diabetic rat femurs. Losartan, an angiotensin II type 1 receptor blocker, has a therapeutic effect on the physicochemical properties of diabetic bone resulting in improvement of bone strength at the material level. Therefore, specific inhibition of this pathway at the receptor level shows potential as a therapeutic target for diabetic patients suffering from bone diseases such as osteopenia.

Prepubescent Strength Training. Some Considerations.

ERIC Educational Resources Information Center

Priest, Joe W.; Holshouser, Richard S.

1987-01-01

Under the careful supervision of a trained fitness professional, the benefits of prepubescent strength training (improved strength, power, muscular endurance, bone density) outweigh the risks (acute and chronic musculoskeletal injuries). (CB)

[Clinical usefulness of bone turnover markers in the management of osteoporosis].

PubMed

Yano, Shozo

2013-09-01

Osteoporosis is a state of elevated risk for bone fracture due to depressed bone strength, which is considered to be the sum of bone mineral density and bone quality. Since a measure of bone quality has not been established, bone mineral density and bone turnover markers are the only way to evaluate bone strength. Bone turnover markers are classified into bone formation marker and resorption marker, which are correlated with the bone formation rate and resorption rate, respectively, and bone matrix-related marker. Bone is always metabolized; old tissue is resorbed by acids and proteases derived from osteoclasts, whereas new bone is produced by osteoblasts. Bone formation and resorption rates should be balanced (also called coupled). When the bone resorption rate exceeds the formation rate(uncoupled state), bone volume will be reduced. Thus, we can comprehend bone metabolism by measuring both formation and resorption markers at the same time. Increased fracture risk is recognized by elevated bone resorption markers and undercarboxylated osteocalcin, which reflects vitamin K insufficiency and bone turnover. These values and the time course give us helpful information to choose medicine suitable for the patients and to judge the responsiveness. If the value is extraordinarily high without renal failure, metabolic bone disorder or bone metastatic tumor should be considered. Bone quality may be assessed by measuring bone matrix-related markers such as homocystein and pentosidine. Since recent studies indicate that the bone is a hormone-producing organ, it is possible that glucose metabolism or an unknown mechanism could be assessed in the future.

Miniature X-Ray Bone Densitometer

NASA Technical Reports Server (NTRS)

Charles, Harry K., Jr.

1999-01-01

The purpose of the Dual Energy X-ray Absorptiometry (DEXA) project is to design, build, and test an advanced X-ray absorptiometry scanner capable of being used to monitor the deleterious effects of weightlessness on the human musculoskeletal system during prolonged spaceflight. The instrument is based on the principles of dual energy x-ray absorptiometry and is designed not only to measure bone, muscle, and fat masses but also to generate structural information about these tissues so that the effects on mechanical integrity may be assessed using biomechanical principles. A skeletal strength assessment could be particularly important for an astronaut embarking on a remote planet where the consequences of a fragility fracture may be catastrophic. The scanner will employ multiple projection images about the long axis of the scanned subject to provide geometric properties in three dimensions, suitable for a three-dimensional structural analysis of the scanned region. The instrument will employ advanced fabrication techniques to minimize volume and mass (100 kg current target with a long-term goal of 60 kg) of the scanner as appropriate for the space environment, while maintaining the required mechanical stability for high precision measurement. The unit will have the precision required to detect changes in bone mass and geometry as small as 1% and changes in muscle mass as small as 5%. As the system evolves, advanced electronic fabrication technologies such as chip-on-board and multichip modules will be combined with commercial (off-the-shelf) parts to produce a reliable, integrated system which not only minimizes size and weight, but, because of its simplicity, is also cost effective to build and maintain. Additionally, the system is being designed to minimize power consumption. Methods of heat dissipation and mechanical stowage (for the unit when not in use) are being optimized for the space environment.

N-acetylcysteine supplementation decreases osteoclast differentiation and increases bone mass in mice fed a high-fat diet

USDA-ARS?s Scientific Manuscript database

Studies have demonstrated that obesity induced by high-fat diets increases bone resorption, decreases trabecular bone mass, and reduces bone strength in various animal models. This study investigated whether N-acetylcysteine (NAC), an antioxidant and a glutathione precursor, alters glutathione statu...

Physical activity and 5-year changes in physical performance tests and bone mineral density in postmenopausal women: the Yokogoshi Study.

PubMed

Kitamura, Kaori; Nakamura, Kazutoshi; Kobayashi, Ryosaku; Oshiki, Rieko; Saito, Toshiko; Oyama, Mari; Takahashi, Shunsuke; Nishiwaki, Tomoko; Iwasaki, Masanori; Yoshihara, Akihiro

2011-09-01

The effect of physical activity on musculoskeletal health in older adults is not completely understood. The aim of this study was to determine the relationship between physical activity and 5-year changes in physical performance tests and bone mineral density (BMD) in postmenopausal women. The design was a 5-year cohort study. Subjects were 507 women (55-74 years old) living in a rural community in Japan. Physical activity assessed included housework, farm work, and moderate leisure-time physical activity within the previous week. Measurements at baseline included handgrip strength, walking time (timed "Up & Go" test) and BMD of the femoral neck and vertebrae. Five-year changes in these measures (outcome variables) were compared among groups with different levels of physical activity by analysis of covariance. Women who did not do housework performed worse in changes in handgrip strength (difference=2.22 kg, P=0.0201) and worse in changes in the walking time (difference=0.54 s, P=0.0072) than those who did housework alone. Women who spent at least 9h per week (median=24) doing farm work performed better in changes in handgrip strength (difference=0.28 kg, P=0.0334), but worse in changes in the walking time (difference=0.66 s, P<0.0001) than those who did not do farm work. However, leisure-time activity was not associated with changes in any outcome variable, and none of the physical activities predicted BMD changes. Engaging in housework and farm work are determinants of physical function in postmenopausal women, which may help them maintain independence in daily living. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Influence of recreational activity and muscle strength on ulnar bending stiffness in men

NASA Technical Reports Server (NTRS)

Myburgh, K. H.; Charette, S.; Zhou, L.; Steele, C. R.; Arnaud, S.; Marcus, R.

1993-01-01

Bone bending stiffness (modulus of elasticity [E] x moment of inertia [I]), a measure of bone strength, is related to its mineral content (BMC) and geometry and may be influenced by exercise. We evaluated the relationship of habitual recreational exercise and muscle strength to ulnar EI, width, and BMC in 51 healthy men, 28-61 yr of age. BMC and width were measured by single photon absorptiometry and EI by mechanical resistance tissue analysis. Maximum biceps strength was determined dynamically (1-RM) and grip strength isometrically. Subjects were classified as sedentary (S) (N = 13), moderately (M) (N = 18), or highly active (H) (N = 20) and exercised 0.2 +/- 0.2; 2.2 +/- 1.3; and 6.8 +/- 2.3 h.wk-1 (P < 0.001). H had greater biceps (P < 0.0005) and grip strength (P < 0.05), ulnar BMC (P < 0.05), and ulnar EI (P = 0.01) than M or S, who were similar. Amount of activity correlated with grip and biceps strength (r = 0.47 and 0.49; P < 0.001), but not with bone measurements, whereas muscle strength correlated with both EI and BMC (r = 0.40-0.52, P < 0.005). EI also correlated significantly with both BMC and ulnar width (P < 0.0001). Ulnar width and biceps strength were the only independent predictors of EI (r2 = 0.67, P < 0.0001). We conclude that levels of physical activity sufficient to increase arm strength influence ulnar bending stiffness.

Ethnic Differences in Bone Health

PubMed Central

Zengin, Ayse; Prentice, Ann; Ward, Kate Anna

2015-01-01

There are differences in bone health between ethnic groups in both men and in women. Variations in body size and composition are likely to contribute to reported differences. Most studies report ethnic differences in areal bone mineral density (aBMD), which do not consistently parallel ethnic patterns in fracture rates. This suggests that other parameters beside aBMD should be considered when determining fracture risk between and within populations, including other aspects of bone strength: bone structure and microarchitecture, as well as muscle strength (mass, force generation, anatomy) and fat mass. We review what is known about differences in bone-densitometry-derived outcomes between ethnic groups and the extent to which they account for the differences in fracture risk. Studies are included that were published primarily between 1994 and 2014. A “one size fits all approach” should definitely not be used to understand better ethnic differences in fracture risk. PMID:25852642

Accuracy of specimen-specific nonlinear finite element analysis for evaluation of radial diaphysis strength in cadaver material.

PubMed

Matsuura, Yusuke; Kuniyoshi, Kazuki; Suzuki, Takane; Ogawa, Yasufumi; Sukegawa, Koji; Rokkaku, Tomoyuki; Thoreson, Andrew Ryan; An, Kai-Nan; Takahashi, Kazuhisa

2015-01-01

The feasibility of a user-specific finite element model for predicting the in situ strength of the radius after implantation of bone plates for open fracture reduction was established. The effect of metal artifact in CT imaging was characterized. The results were verified against biomechanical test data. Fourteen cadaveric radii were divided into two groups: (1) intact radii for evaluating the accuracy of radial diaphysis strength predictions with finite element analysis and (2) radii with a locking plate affixed for evaluating metal artifact. All bones were imaged with CT. In the plated group, radii were first imaged with the plates affixed (for simulating digital plate removal). They were then subsequently imaged with the locking plates and screws removed (actual plate removal). Fracture strength of the radius diaphysis under axial compression was predicted with a three-dimensional, specimen-specific, nonlinear finite element analysis for both the intact and plated bones (bones with and without the plate captured in the scan). Specimens were then loaded to failure using a universal testing machine to verify the actual fracture load. In the intact group, the physical and predicted fracture loads were strongly correlated. For radii with plates affixed, the physical and predicted (simulated plate removal and actual plate removal) fracture loads were strongly correlated. This study demonstrates that our specimen-specific finite element analysis can accurately predict the strength of the radial diaphysis. The metal artifact from CT imaging was shown to produce an overestimate of strength.

Cortical bone deficit and fat infiltration of bone marrow and skeletal muscle in ambulatory children with mild spastic cerebral palsy

PubMed Central

Whitney, Daniel G.; Singh, Harshvardhan; Miller, Freeman; Barbe, Mary F.; Slade, Jill M.; Pohlig, Ryan T.; Modlesky, Christopher M.

2016-01-01

Introduction Nonambulatory children with severe cerebral palsy (CP) have an underdeveloped bone architecture, low bone strength and a high degree of fat infiltration in the lower extremity musculature. The present study aims to determine if such a profile exists in ambulatory children with mild CP and if excess fat infiltration extends into the bone marrow. Materials and methods Ambulatory children with mild spastic CP and typically developing children (4 to 11 years; 12/group) were tested. Magnetic resonance imaging was used to estimate cortical, medullary and total bone volume and width, bone strength [i.e., section modulus (Z) and polar moment of inertia (J)], and bone marrow fat concentration in the midtibia, and muscle volume, intermuscular, subfascial, and subcutaneous adipose tissue (AT) volume and intramuscular fat concentration in the midleg. Physical activity monitors worn on the ankle were used to assess physical activity. Results There were no group differences in age, height, body mass, body mass percentile, BMI, BMI percentile or tibia length, but children with CP had lower height percentile (19th vs. 50th percentile) and total physical activity counts (44 %) than controls (both p < 0.05). Children with CP also had lower cortical volume (30 %), cortical width in the posterior (16 %) and medial (32 %) portion of the shaft, total bone width in the medial-lateral direction (15 %), Z in the medial-lateral direction (34 %), J (39 %) and muscle volume (39 %), and higher bone marrow fat concentration (82.1 ± 1.8 % vs. 80.5 ± 1.9 %), subfascial AT volume (3.3 fold) and intramuscular fat concentration (25.0 ± 8.0 % vs. 16.1 ± 3.3 %) than controls (all p < 0.05). When tibia length was statistically controlled, all group differences in bone architecture, bone strength, muscle volume and fat infiltration estimates, except posterior cortical width, were still present (all p < 0.05). Furthermore, a higher intermuscular AT volume in children with CP compared to controls emerged (p < 0.05). Conclusions Ambulatory children with mild CP exhibit an underdeveloped bone architecture and low bone strength in the midtibia and a greater infiltration of fat in the bone marrow and surrounding musculature compared to typically developing children. Whether the deficit in the musculoskeletal system of children with CP is associated with higher chronic disease risk and whether the deficit can be mitigated requires further investigation. PMID:27732905

In vivo evaluation of CaO-SiO2-P2O5-B2O3 glass-ceramics coating on Steinman pins.

PubMed

Lee, Jae Hyup; Hong, Kug Sun; Baek, Hae-Ri; Seo, Jun-Hyuk; Lee, Kyung Mee; Ryu, Hyun-Seung; Lee, Hyun-Kyung

2013-07-01

Surface coating using ceramics improves the bone bonding strength of an implant. We questioned whether a new type of glass-ceramics (BGS-7) coating (CaO-SiO2 -P2 O5 -B2 O3 ) would improve the osseointegration of Steinman pins (S-pins) both biomechanically and histomorphometrically. An in vivo study was performed using rabbits by inserting three S-pins into each iliac bone. The pins were 2.2-mm S-pins with a coating of 30-μm-thick BGS-7 and 550-nm-thick hydroxyapatite (HA), as opposed to an S-pin without coating. A tensile strength test and histomorphometrical evaluation was performed. In the 2-week group, the BGS-7 implant showed a significantly higher tensile strength than the S-pin. In the 4- and 8-week groups, the BGS-7 implants had significantly higher tensile strengths than the S-pins and HA implants. The histomorphometrical study revealed that the BGS-7 implant had a significantly higher contact ratio than the S-pin and HA implants in the 4-week group. The biomechanical and histomorphometrical tests showed that the BGS-7 coating had superior bone bonding properties than the groups without the coating from the initial stage of insertion. The BGS-7 coating of an S-pin will enhance the bone bonding strength, and there might also be an advantage in human bone bonding. © 2013, Copyright the Authors. Artificial Organs © 2013, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Mechanical characterization of structurally porous biomaterials built via additive manufacturing: experiments, predictive models, and design maps for load-bearing bone replacement implants.

PubMed

Melancon, D; Bagheri, Z S; Johnston, R B; Liu, L; Tanzer, M; Pasini, D

2017-11-01

Porous biomaterials can be additively manufactured with micro-architecture tailored to satisfy the stringent mechano-biological requirements imposed by bone replacement implants. In a previous investigation, we introduced structurally porous biomaterials, featuring strength five times stronger than commercially available porous materials, and confirmed their bone ingrowth capability in an in vivo canine model. While encouraging, the manufactured biomaterials showed geometric mismatches between their internal porous architecture and that of its as-designed counterpart, as well as discrepancies between predicted and tested mechanical properties, issues not fully elucidated. In this work, we propose a systematic approach integrating computed tomography, mechanical testing, and statistical analysis of geometric imperfections to generate statistical based numerical models of high-strength additively manufactured porous biomaterials. The method is used to develop morphology and mechanical maps that illustrate the role played by pore size, porosity, strut thickness, and topology on the relations governing their elastic modulus and compressive yield strength. Overall, there are mismatches between the mechanical properties of ideal-geometry models and as-manufactured porous biomaterials with average errors of 49% and 41% respectively for compressive elastic modulus and yield strength. The proposed methodology gives more accurate predictions for the compressive stiffness and the compressive strength properties with a reduction of the average error to 11% and 7.6%. The implications of the results and the methodology here introduced are discussed in the relevant biomechanical and clinical context, with insight that highlights promises and limitations of additively manufactured porous biomaterials for load-bearing bone replacement implants. In this work, we perform mechanical characterization of load-bearing porous biomaterials for bone replacement over their entire design space. Results capture the shift in geometry and mechanical properties between as-designed and as-manufactured biomaterials induced by additive manufacturing. Characterization of this shift is crucial to ensure appropriate manufacturing of bone replacement implants that enable biological fixation through bone ingrowth as well as mechanical property harmonization with the native bone tissue. In addition, we propose a method to include manufacturing imperfections in the numerical models that can reduce the discrepancy between predicted and tested properties. The results give insight into the use of structurally porous biomaterials for the design and additive fabrication of load-bearing implants for bone replacement. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effects of the combination of vitamin K and teriparatide on the bone metabolism in ovariectomized rats.

PubMed

Nagura, Nana; Komatsu, Jun; Iwase, Hideaki; Hosoda, Hiroshi; Ohbayashi, Osamu; Nagaoka, Isao; Kaneko, Kazuo

2015-05-01

The purpose of the present study was to evaluate the combined effects of vitamin K (VK) and teriparatide (TPTD) on bone mineral density (BMD), mechanical strength and other parameters for bone metabolism using a rat ovariectomized osteoporosis model. Ovariectomized female Sprague-Dawley rats were administered with VK (an oral dose of 30 mg/kg/day), TPTD (a subcutaneous dose of 30 µg/kg, three times a week) or a combination for 8 weeks. Thereafter, serum levels of γ-carboxylated osteocalcin (Gla-OC) were quantitated by ELISA; BMD and mechanical strength were measured by computed tomography and biomechanical testing, respectively at the femoral metaphysis. Additionally, histomorphometry was performed using the toluidine blue-stained coronal sections of distal femur. The combination of VK and TPTD clearly increased the serum levels of Gla-OC (a specific marker for bone formation) and osteoblast surface (the number of osteoblasts attaching with the surface of cancellous bone), compared to VK or TPTD alone. In addition, the combination of the two agents improved the BMD and bone strength of the femur in the ovariectomized rats, compared to VK or TPTD alone. Taken together, these findings suggest that the treatment with VK and TPTD may have a therapeutic advantage over VK or TPTD monotherapy for postmenopausal osteoporosis, possibly by enhancing the bone formation through the actions on OC and osteoblasts.

Effects of the combination of vitamin K and teriparatide on the bone metabolism in ovariectomized rats

PubMed Central

NAGURA, NANA; KOMATSU, JUN; IWASE, HIDEAKI; HOSODA, HIROSHI; OHBAYASHI, OSAMU; NAGAOKA, ISAO; KANEKO, KAZUO

2015-01-01

The purpose of the present study was to evaluate the combined effects of vitamin K (VK) and teriparatide (TPTD) on bone mineral density (BMD), mechanical strength and other parameters for bone metabolism using a rat ovariectomized osteoporosis model. Ovariectomized female Sprague-Dawley rats were administered with VK (an oral dose of 30 mg/kg/day), TPTD (a subcutaneous dose of 30 µg/kg, three times a week) or a combination for 8 weeks. Thereafter, serum levels of γ-carboxylated osteocalcin (Gla-OC) were quantitated by ELISA; BMD and mechanical strength were measured by computed tomography and biomechanical testing, respectively at the femoral metaphysis. Additionally, histomorphometry was performed using the toluidine blue-stained coronal sections of distal femur. The combination of VK and TPTD clearly increased the serum levels of Gla-OC (a specific marker for bone formation) and osteoblast surface (the number of osteoblasts attaching with the surface of cancellous bone), compared to VK or TPTD alone. In addition, the combination of the two agents improved the BMD and bone strength of the femur in the ovariectomized rats, compared to VK or TPTD alone. Taken together, these findings suggest that the treatment with VK and TPTD may have a therapeutic advantage over VK or TPTD monotherapy for postmenopausal osteoporosis, possibly by enhancing the bone formation through the actions on OC and osteoblasts. PMID:26137225

Effect of whole body vibration training on quadriceps strength, bone mineral density, and functional capacity in children with hemophilia: a randomized clinical trial.

PubMed

El-Shamy, S

2017-06-01

The objective was to evaluate the effects of whole body vibration training on quadriceps strength, bone mineral density, and functional capacity in children with hemophilia. Thirty children with hemophilia with age ranging from 9 to 13 years were selected and randomly assigned to either the study group that received whole body vibration training (30-40 Hz, 2-4 mm of peak-to-peak vertical plate displacement for 15 minutes/day, 3 days/week/ 12 weeks) plus the conventional physical therapy program or the control group that performed a conventional physical therapy program only. Outcomes included quadriceps strength, bone mineral density, and the functional capacity. Children in the study group showed a significant improvement in all outcomes compared with the control group. The quadriceps peak torque after treatment was 70.26 and 56.46 Nm for the study and control group, respectively (p⟨0.001). The lumbar spine bone mineral density after treatment was 0.85 and 0.72 g/cm 2 for the study and control group, respectively (p⟨0.001). The functional capacity after treatment was 325 and 290 m for the study and control group, respectively (p=0.006). Whole body vibration training is an effective modality in increasing quadriceps strength, bone mineral density, and functional capacity in children with hemophilia.

Effect of whole body vibration training on quadriceps strength, bone mineral density, and functional capacity in children with hemophilia: a randomized clinical trial

PubMed Central

El-Shamy, S.

2017-01-01

Objectives: The objective was to evaluate the effects of whole body vibration training on quadriceps strength, bone mineral density, and functional capacity in children with hemophilia. Methods: Thirty children with hemophilia with age ranging from 9 to 13 years were selected and randomly assigned to either the study group that received whole body vibration training (30-40 Hz, 2-4 mm of peak-to-peak vertical plate displacement for 15 minutes/day, 3 days/week/ 12 weeks) plus the conventional physical therapy program or the control group that performed a conventional physical therapy program only. Outcomes included quadriceps strength, bone mineral density, and the functional capacity. Results: Children in the study group showed a significant improvement in all outcomes compared with the control group. The quadriceps peak torque after treatment was 70.26 and 56.46 Nm for the study and control group, respectively (p<0.001). The lumbar spine bone mineral density after treatment was 0.85 and 0.72 g/cm2 for the study and control group, respectively (p<0.001). The functional capacity after treatment was 325 and 290 m for the study and control group, respectively (p=0.006). Conclusions: Whole body vibration training is an effective modality in increasing quadriceps strength, bone mineral density, and functional capacity in children with hemophilia. PMID:28574408

Administration of growth hormone in selectively protein-deprived rats decreases BMD and bone strength.

PubMed

Ammann, Patrick; Brennan, Tara C; Mekraldi, Samia; Aubert, Michel L; Rizzoli, René

2010-06-01

Isocaloric protein undernutrition is associated with decreased bone mass and decreased bone strength, together with lower IGF-I levels. It remains unclear whether administration of growth hormone (GH) corrects these alterations in bone metabolism. Six-month-old female rats were fed isocaloric diets containing either 2.5% or 15% casein for 2 weeks. Bovine growth hormone (bGH, 0.5 or 2.5mg/kg of body weight) or vehicle was then administered as subcutaneous injections, twice daily, to rats on either diet for 4 weeks. At the proximal tibia, analysis of bone mineral density (BMD), maximal load and histomorphometry were performed. In addition, urinary deoxypyridinoline, plasma osteocalcin and IGF-I concentrations were measured. Weight was monitored weekly. bGH caused a dose-dependent increase in plasma IGF-I regardless of the dietary protein content. However, bGH dose-dependently decreased BMD and bone strength in rats fed the low-protein diet. There was no significant effect of bGH on BMD in rats fed the normal protein diet within this short-term treatment period, however bone formation as detected by histomorphometry was improved in this group but not the low-protein group. Osteoclast surface was increased in the low-protein bGH-treated animals only. Changes in bone turnover markers were detectable under both normal and low-protein diets. These results emphasize the major importance of dietary protein intake in the bone response to short-term GH administration, and highlight the need for further investigation into the effects of GH treatment in patients with reduced protein intake. Copyright 2010 Elsevier Inc. All rights reserved.

Comparative Efficacies of Collagen-Based 3D Printed PCL/PLGA/β-TCP Composite Block Bone Grafts and Biphasic Calcium Phosphate Bone Substitute for Bone Regeneration.

PubMed

Hwang, Kyoung-Sub; Choi, Jae-Won; Kim, Jae-Hun; Chung, Ho Yun; Jin, Songwan; Shim, Jin-Hyung; Yun, Won-Soo; Jeong, Chang-Mo; Huh, Jung-Bo

2017-04-17

The purpose of this study was to compare bone regeneration and space maintaining ability of three-dimensional (3D) printed bone grafts with conventional biphasic calcium phosphate (BCP). After mixing polycaprolactone (PCL), poly (lactic-co-glycolic acid) (PLGA), and β-tricalcium phosphate (β-TCP) in a 4:4:2 ratio, PCL/PLGA/β-TCP particulate bone grafts were fabricated using 3D printing technology. Fabricated particulate bone grafts were mixed with atelocollagen to produce collagen-based PCL/PLGA/β-TCP composite block bone grafts. After formation of calvarial defects 8 mm in diameter, PCL/PLGA/β-TCP composite block bone grafts and BCP were implanted into bone defects of 32 rats. Although PCL/PLGA/β-TCP composite block bone grafts were not superior in bone regeneration ability compared to BCP, the results showed relatively similar performance. Furthermore, PCL/PLGA/β-TCP composite block bone grafts showed better ability to maintain bone defects and to support barrier membranes than BCP. Therefore, within the limitations of this study, PCL/PLGA/β-TCP composite block bone grafts could be considered as an alternative to synthetic bone grafts available for clinical use.

Clinical Imaging of Bone Microarchitecture with HR-pQCT

PubMed Central

Nishiyama, Kyle K.; Shane, Elizabeth

2014-01-01

Osteoporosis, a disease characterized by loss of bone mass and structural deterioration, is currently diagnosed by dual-energy x-ray absorptiometry (DXA). However, DXA does not provide information about bone microstructure, which is a key determinant of bone strength. Recent advances in imaging permit the assessment of bone microstructure in vivo using high-resolution peripheral quantitative computed tomography (HR-pQCT). From these data, novel image processing techniques can be applied to characterize bone quality and strength. To date, most HR-pQCT studies are cross-sectional comparing subjects with and without fracture. These studies have shown that HR-pQCT is capable of discriminating fracture status independent of DXA. Recent longitudinal studies present new challenges in terms of analyzing the same region of interest and multisite calibrations. Careful application of analysis techniques and educated clinical interpretation of HR-pQCT results have improved our understanding of various bone-related diseases and will no doubt continue to do so in the future. PMID:23504496

Loading of Hip Measured by Hip Contact Forces at Different Speeds of Walking and Running.

PubMed

Giarmatzis, Georgios; Jonkers, Ilse; Wesseling, Mariska; Van Rossom, Sam; Verschueren, Sabine

2015-08-01

Exercise plays a pivotal role in maximizing peak bone mass in adulthood and maintaining it through aging, by imposing mechanical loading on the bone that can trigger bone mineralization and growth. The optimal type and intensity of exercise that best enhances bone strength remains, however, poorly characterized, partly because the exact peak loading of the bone produced by the diverse types of exercises is not known. By means of integrated motion capture as an input to dynamic simulations, contact forces acting on the hip of 20 young healthy adults were calculated during walking and running at different speeds. During walking, hip contact forces (HCFs) have a two-peak profile whereby the first peak increases from 4.22 body weight (BW) to 5.41 BW and the second from 4.37 BW to 5.74 BW, by increasing speed from 3 to 6 km/h. During running, there is only one peak HCF that increases from 7.49 BW to 10.01 BW, by increasing speed from 6 to 12 km/h. Speed related profiles of peak HCFs and ground reaction forces (GRFs) reveal a different progression of the two peaks during walking. Speed has a stronger impact on peak HCFs rather than on peak GRFs during walking and running, suggesting an increasing influence of muscle activity on peak HCF with increased speed. Moreover, results show that the first peak of HCF during walking can be predicted best by hip adduction moment, and the second peak of HCF by hip extension moment. During running, peak HCF can be best predicted by hip adduction moment. The present study contributes hereby to a better understanding of musculoskeletal loading during walking and running in a wide range of speeds, offering valuable information to clinicians and scientists exploring bone loading as a possible nonpharmacological osteogenic stimulus. © 2015 American Society for Bone and Mineral Research. © 2015 American Society for Bone and Mineral Research.

Preliminary evaluation of a load-bearing BMP-2 carrier for segmental defect regeneration.

PubMed

Chu, Tien-Min G; Sargent, Peter; Warden, Stuart J; Turner, Charles H; Stewart, Rena L

2006-01-01

Large segmental defects in bones can result from tumor removal, massive trauma, congenital malformation, or non-union fractures. Such defects often are difficult to manage and require multiple-phase surgery to achieve adequate union and function. In this study, we propose a novel design of bone morphogenetic protein 2 (BMP-2) carrier for tissue engineering of segmental defect regeneration. The tube-shaped BMP-2 carrier was fabrication from a poly(propylene fumarate)/tricalcium phosphate (PPF/TCP) composite via casting technique developed in our laboratory. An in vitro evaluation showed that the compressive strength of the carrier decreased about 48% in 12 weeks while maintained a pH in the 6.8-7.4 range. In vivo study was conducted by implanting carriers loaded with 10 microg of BMP-2 in 5 mm rat femur gap model for 15 weeks. X-ray evidence of bridging was first found in the BMP group at 3 weeks. Bridging in all animals (N = 4) in the BMP group was found at 9 weeks. No x-ray evidence of bridging was found in the No BMP group (N = 3). pQCT analysis indicated that the bone mineral density of the callus in the BMP group has reached the level of native femur at 15 weeks after implantation, while the callus in the No BMP group has a bone mineral density at a lower level of 84% to the native femur. Histology analysis shows that a normal fatty bone marrow was restored and mineralized callus formed and bridged the segmental defect.

INCREASING DURATION OF TYPE 1 DIABETES PERTURBS THE STRENGTH-STRUCTURE RELATIONSHIP AND INCREASES BRITTLENESS OF BONE

PubMed Central

Nyman, Jeffry S.; Even, Jesse L.; Jo, Chan-Hee; Herbert, Erik G.; Murry, Matthew R.; Cockrell, Gael E.; Wahl, Elizabeth C.; Bunn, R. Clay; Lumpkin, Charles K.; Fowlkes, John L.; Thrailkill, Kathryn M.

2011-01-01

Type 1 diabetes (T1DM) increases the likelihood of a fracture. Despite serious complications in the healing of fractures among those with diabetes, the underlying causes are not delineated for the effect of diabetes on the fracture resistance of bone. Therefore, in a mouse model of T1DM, we have investigated the possibility that a prolonged state of diabetes perturbs the relationship between bone strength and structure (i.e., affects tissue properties). At 10, 15, and 18 weeks following injection of streptozotocin to induce diabetes, diabetic male mice and age-matched controls were examined for measures of skeletal integrity. We assessed 1) the moment of inertia (IMIN) of the cortical bone within diaphysis, trabecular bone architecture of the metaphysis, and mineralization density of the tissue (TMD) for each compartment of the femur by microcomputed tomography and 2) biomechanical properties by three point bending test (femur) and nanoindentation (tibia). In the metaphysis, a significant decrease in trabecular bone volume fraction and trabecular TMD was apparent after 10 weeks of diabetes. For cortical bone, type 1 diabetes was associated with decreased cortical TMD, IMIN, rigidity, and peak moment as well as a lack of normal age-related increases in the biomechanical properties. However, there were only modest differences in material properties between diabetic and normal mice at both whole bone and tissue-levels. As the duration of diabetes increased, bone toughness decreased relative to control. If the sole effect of diabetes on bone strength was due to a reduction in bone size, then IMIN would be the only significant variable explaining the variance in the maximum moment. However, general linear modeling found that the relationship between peak moment and IMIN depended on whether the bone was from a diabetic mouse and the duration of diabetes. Thus, these findings suggest that the elevated fracture risk among diabetics is impacted by complex changes in tissue properties that ultimately reduce the fracture resistance of bone. PMID:21185416

A comparison of screw insertion torque and pullout strength.

PubMed

Ricci, William M; Tornetta, Paul; Petteys, Timothy; Gerlach, Darin; Cartner, Jacob; Walker, Zakiyyah; Russell, Thomas A

2010-06-01

Pullout strength of screws is a parameter used to evaluate plate screw fixation strength. However, screw fixation strength may be more closely related to its ability to generate sufficient insertion because stable nonlocked plate-screw fracture fixation requires sufficient compression between plate and bone such that no motion occurs between the plate and bone under physiological loads. Compression is generated by tightening of screws. In osteoporotic cancellous bone, sufficient screw insertion torque may not be generated before screw stripping. The effect of screw thread pitch on generation of maximum insertion torque (MIT) and pullout strength (POS) was investigated in an osteoporotic cancellous bone model and the relationship between MIT and POS was analyzed. Stainless steel screws with constant major (5.0 mm) and minor (2.7 mm) diameters but with varying thread pitches (1, 1.2, 1.5, 1.6, and 1.75 mm) were tested for MIT and POS in a validated osteoporotic surrogate for cancellous bone (density of 160 kg/m(3) [10 lbs/ft(3)]). MIT was measured with a torque-measuring hex driver for screws inserted through a one-third tubular plate. POS was measured after insertion of screws to a depth of 20 mm based on the Standard Specification and Test Methods for Metallic Medical Bone Screws (ASTM F 543-07). Five screws were tested for each failure mode and screw design. The relationship between MIT and compressive force between the plate and bone surrogate was evaluated using pressure-sensitive film. There was a significant difference in mean MIT based on screw pitch (P < 0.0001), whereas POS did not show statistically significant differences among the different screw pitches (P = 0.052). Small screw pitches (1.0 mm and 1.2 mm) had lower MIT and were distinguished from large pitches (1.5 mm, 1.6 mm, and the 1.75 mm) with higher MIT. For POS, only the 1-mm and 1.6-mm pitch screws were found to be different from each other. Linear regression analysis of MIT revealed a moderate correlation to the screw pitch (R(2) = 0.67, P < 0.0001), whereas the analysis of POS suggested no correlation to the screw pitch (R(2) = 0.28, P = 0.006). Pearson correlation analysis indicated no correlation between MIT and POS (P = 0.069, r = -0.37). A linear relationship of increased compression between the plate and bone surrogate was found for increasing screw torque (R(2) = 0.97). These results indicate that the ability of different screw designs to generate high screw insertion torque in a model of osteoporotic cancellous bone is unrelated to their pullout strength. Therefore, extrapolation of results for POS to identify optimal screw design for osteoporotic bone may not be valid. Screw designs that optimize MIT should be sought for fixation in osteoporotic bone.

High-fat Diet Decreases Cancellous Bone Mass But Has No Effect on Cortical Bone Mass in the Tibia in Mice

USDA-ARS?s Scientific Manuscript database

Introduction: Body mass has a positive effect on bone mineral density and the strength. Whether mass derived from an obesity condition is beneficial to bone has not been established; neither have the mechanism by which obesity affects bone metabolism. The aim of this study was to examine the effects...

Tactile/kinesthetic stimulation (TKS) increases tibial speed of sound and urinary osteocalcin (U-MidOC and unOC) in premature infants (29-32weeks PMA).

PubMed

Haley, S; Beachy, J; Ivaska, K K; Slater, H; Smith, S; Moyer-Mileur, L J

2012-10-01

Preterm delivery (<37 weeks post-menstrual age) is associated with suboptimal bone mass. We hypothesized that tactile/kinesthetic stimulation (TKS), a form of infant massage that incorporates kinesthetic movement, would increase bone strength and markers of bone accretion in preterm infants. Preterm, AGA infants (29-32 weeks) were randomly assigned to TKS (N=20) or Control (N=20). Twice daily TKS was provided 6 days per week for 2 weeks. Control infants received the same care without TKS treatment. Treatment was masked to parents, health care providers, and study personnel. Baseline and week two measures were collected for tibial speed of sound (tSOS, m/sec), a surrogate for bone strength, by quantitative ultrasound (Sunlight8000) and urine markers of bone metabolism, pyridinium crosslinks and osteocalcin (U-MidOC and unOC). Infant characteristics at birth and study entry as well as energy/nutrient intake were similar between TKS and Control. TKS intervention attenuated the decrease in tSOS observed in Control infants (p<0.05). Urinary pyridinium crosslinks decreased over time in both TKS and CTL (p<0.005). TKS infants experienced greater increases in urinary osteocalcin (U-MidOC, p<0.001 and unOC, p<0.05). We conclude that TKS improves bone strength in premature infants by attenuating the decrease that normally follows preterm birth. Further, biomarkers of bone metabolism suggest a modification in bone turnover in TKS infants in favor of bone accretion. Taken together, we speculate that TKS improves bone mineralization. Copyright © 2012 Elsevier Inc. All rights reserved.

In-vitro biocompatibility, bioactivity, and mechanical strength of PMMA-PCL polymer containing fluorapatite and graphene oxide bone cements.

PubMed

Pahlevanzadeh, F; Bakhsheshi-Rad, H R; Hamzah, E

2018-06-01

In this study, a bone cement consisting of poly methyl methacrylate (PMMA)-poly caprolactone (PCL)-fluorapatite (FA)-graphene oxide (GO) was synthesized as bone filler for application in orthopedic surgeries. The FA and GO particulates were homogenously distributed in the PMMA-PCL polymer matrix and no defects and agglomeration were found in the PMMA-PCL/FA/GO bone cement. The in-vitro bioactivity result exhibited that addition of FA and GO to the polymer cement (PMMA-PCL) improved the apatite formation ability on the surface of polymer. The results also showed that addition of FA to the polymer bone cement escalated the compressive strength and elastic modulus while reducing elongation to 8 ± 2%. However, after addition of GO into the PMMA-PCL/FA bone cement, both compressive strength and elongation considerably increased to 101 ± 5 MPa and 35 ± 6%, respectively. Furthermore, tensile tests exhibited that inclusion of GO was favorable in improving the tensile modulus, UTS and elongation of the PMMA-PCL/FA bone cement. The cytotoxicity test pointed out that MG63 osteoblast cells viability increased to 279 ± 15% after addition of FA and GO to the PMMA-PCL polymer bone cement. The DAPI (4',6-diamidino-2-phenylindole) staining demonstrated better spreading and attachment of MG63 cells on PMMA-PCL/FA/GO surface compared to the PMMA-PCL bone cements. These results confirm the suitable mechanical properties and favorable bioactivity along with high cells viability of PMMA-PCL/FA/GO bone cement, indicating its potentials for orthopedic applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

Boron supplementation improves bone health of non-obese diabetic mice.

PubMed

Dessordi, Renata; Spirlandeli, Adriano Levi; Zamarioli, Ariane; Volpon, José Batista; Navarro, Anderson Marliere

2017-01-01

Diabetes Mellitus is a condition that predisposes a higher risk for the development of osteoporosis. The objective of this study was to investigate the influence of boron supplementation on bone microstructure and strength in control and non-obese diabetic mice for 30days. The animals were supplemented with 40μg/0,5ml of boron solution and controls received 0,5ml of distilled water daily. We evaluated the biochemical parameters: total calcium, phosphorus, magnesium and boron; bone analysis: bone computed microtomography, and biomechanical assay with a three point test on the femur. This study consisted of 28 animals divided into four groups: Group water control - Ctrl (n=10), Group boron control - Ctrl±B (n=8), Group diabetic water - Diab (n=5) and Group diabetic boron - Diab±B (n=5). The results showed that cortical bone volume and the trabecular bone volume fraction were higher for Diab±B and Ctrl±B compared to the Diab and Ctrl groups (p≤0,05). The trabecular specific bone surface was greater for the Diab±B group, and the trabecular thickness and structure model index had the worst values for the Diab group. The boron serum concentrations were higher for the Diab±B group compared to non-supplemented groups. The magnesium concentration was lower for Diab and Diab±B compared with controls. The biomechanical test on the femur revealed maintenance of parameters of the bone strength in animals Diab±B compared to the Diab group and controls. The results suggest that boron supplementation improves parameters related to bone strength and microstructure of cortical and trabecular bone in diabetic animals and the controls that were supplemented. Copyright © 2016 Elsevier GmbH. All rights reserved.

Classification of micro-CT images using 3D characterization of bone canal patterns in human osteogenesis imperfecta

NASA Astrophysics Data System (ADS)

Abidin, Anas Z.; Jameson, John; Molthen, Robert; Wismüller, Axel

2017-03-01

Few studies have analyzed the microstructural properties of bone in cases of Osteogenenis Imperfecta (OI), or `brittle bone disease'. Current approaches mainly focus on bone mineral density measurements as an indirect indicator of bone strength and quality. It has been shown that bone strength would depend not only on composition but also structural organization. This study aims to characterize 3D structure of the cortical bone in high-resolution micro CT images. A total of 40 bone fragments from 28 subjects (13 with OI and 15 healthy controls) were imaged using micro tomography using a synchrotron light source (SRµCT). Minkowski functionals - volume, surface, curvature, and Euler characteristics - describing the topological organization of the bone were computed from the images. The features were used in a machine learning task to classify between healthy and OI bone. The best classification performance (mean AUC - 0.96) was achieved with a combined 4-dimensional feature of all Minkowski functionals. Individually, the best feature performance was seen using curvature (mean AUC - 0.85), which characterizes the edges within a binary object. These results show that quantitative analysis of cortical bone microstructure, in a computer-aided diagnostics framework, can be used to distinguish between healthy and OI bone with high accuracy.

3D Powder Printed Bioglass and β-Tricalcium Phosphate Bone Scaffolds.

PubMed

Seidenstuecker, Michael; Kerr, Laura; Bernstein, Anke; Mayr, Hermann O; Suedkamp, Norbert P; Gadow, Rainer; Krieg, Peter; Hernandez Latorre, Sergio; Thomann, Ralf; Syrowatka, Frank; Esslinger, Steffen

2017-12-22

The use of both bioglass (BG) and β tricalcium phosphate (β-TCP) for bone replacement applications has been studied extensively due to the materials' high biocompatibility and ability to resorb when implanted in the body. 3D printing has been explored as a fast and versatile technique for the fabrication of porous bone scaffolds. This project investigates the effects of using different combinations of a composite BG and β-TCP powder for 3D printing of porous bone scaffolds. Porous 3D powder printed bone scaffolds of BG, β-TCP, 50/50 BG/β-TCP and 70/30 BG/β-TCP compositions were subject to a variety of characterization and biocompatibility tests. The porosity characteristics, surface roughness, mechanical strength, viability for cell proliferation, material cytotoxicity and in vitro bioactivity were assessed. The results show that the scaffolds can support osteoblast-like MG-63 cells growth both on the surface of and within the scaffold material and do not show alarming cytotoxicity; the porosity and surface characteristics of the scaffolds are appropriate. Of the two tested composite materials, the 70/30 BG/β-TCP scaffold proved to be superior in terms of biocompatibility and mechanical strength. The mechanical strength of the scaffolds makes them unsuitable for load bearing applications. However, they can be useful for other applications such as bone fillers.

Exercise during long term exposure to space: Value of exercise during space exploration

NASA Technical Reports Server (NTRS)

1990-01-01

There appear to be two general physiological reasons why exercise will be beneficial to space travelers who will experience a weightless and isolated environment for many months or a few years: (1) to alleviate or prevent tissue atrophy (principally bone and muscle), to maintain cardiovascular function, and to prevent deleterious changes in extracellular and cellular fluid volumes and plasma constituents, especially electrolytes; and (2) to maintain whole organism functional physical and physiological status with special reference to neuromuscular coordination (physical skill) and physical fitness (muscle strength and power, flexibility, and aerobic endurance). The latter reason also relates well to the ability of the crew members to resist both general and local fatigue and thus ensure consistent physical performance. Various forms of exercise, performed regularly, could help alleviate boredom and assist the travelers in coping with stress, anxiety, and depression. The type, frequency, duration and intensity of exercise and ways of ensuring that crew members engage in it are discussed.

Analysis of Vertebral Bone Strength, Fracture Pattern, and Fracture Location: A Validation Study Using a Computed Tomography-Based Nonlinear Finite Element Analysis

PubMed Central

Imai, Kazuhiro

2015-01-01

Finite element analysis (FEA) is an advanced computer technique of structural stress analysis developed in engineering mechanics. Because the compressive behavior of vertebral bone shows nonlinear behavior, a nonlinear FEA should be utilized to analyze the clinical vertebral fracture. In this article, a computed tomography-based nonlinear FEA (CT/FEA) to analyze the vertebral bone strength, fracture pattern, and fracture location is introduced. The accuracy of the CT/FEA was validated by performing experimental mechanical testing with human cadaveric specimens. Vertebral bone strength and the minimum principal strain at the vertebral surface were accurately analyzed using the CT/FEA. The experimental fracture pattern and fracture location were also accurately simulated. Optimization of the element size was performed by assessing the accuracy of the CT/FEA, and the optimum element size was assumed to be 2 mm. It is expected that the CT/FEA will be valuable in analyzing vertebral fracture risk and assessing therapeutic effects on osteoporosis. PMID:26029476

Bond strength of an alkylene bis(dilactoyl)-methacrylate bone adhesive: a biomechanical evaluation in sheep.

PubMed

Heiss, Christian; Schettler, Nicky; Wenisch, Sabine; Cords, Sven; Schilke, Frank; Lips, Katrin Susanne; Alt, Volker; Schnettler, Reinhard

2010-01-01

The purpose of this study is to assess the mechanical efficacy of an alkylene bis(dilactoyl)-methacrylate-based degradable bone adhesive in 36 sheep. Bone segmentation with osteotomies of the metaphyseal ulna was performed and adhesive was applied into the osteotomy gaps in 18 sheep. The remaining 18 animals served as controls. The segment was subsequently stabilized without any osteosynthesis in all sheep. Six animals of the adhesive group and 6 controls were killed after 21, 42 and 84 days, respectively. Bond strength of the adhesive and quality of fracture healing was studied using biomechanical, histological and radiological methods. There were no significant differences in biomechanical analysis between both groups at any time. However, an increase of in vivo bond strength with the highest stiffness of 102.83 N/mm(2) was observed in the adhesive group after 84 days. In vitro analysis showed non-significant differences in bond strength during polymerization time. Histomorphometric investigations revealed significant differences in osteotomy cross-section area after 84 days, with higher areas of callus in the control. After 84 days the X-ray examinations showed completely bridged gaps in four of six animals in the adhesive and in five animals in the control group. This bone adhesive exhibited good in vivo and in vitro bond strength and mechanical efficiency in both the short and long term without impairment of physiological fracture healing.

Adhesive strength of total knee endoprostheses to bone cement - analysis of metallic and ceramic femoral components under worst-case conditions.

PubMed

Bergschmidt, Philipp; Dammer, Rebecca; Zietz, Carmen; Finze, Susanne; Mittelmeier, Wolfram; Bader, Rainer

2016-06-01

Evaluation of the adhesive strength of femoral components to the bone cement is a relevant parameter for predicting implant safety. In the present experimental study, three types of cemented femoral components (metallic, ceramic and silica/silane-layered ceramic) of the bicondylar Multigen Plus knee system, implanted on composite femora were analysed. A pull-off test with the femoral components was performed after different load and several cementing conditions (four groups and n=3 components of each metallic, ceramic and silica/silane-layered ceramic in each group). Pull-off forces were comparable for the metallic and the silica/silane-layered ceramic femoral components (mean 4769 N and 4298 N) under standard test condition, whereas uncoated ceramic femoral components showed reduced pull-off forces (mean 2322 N). Loading under worst-case conditions led to decreased adhesive strength by loosening of the interface implant and bone cement using uncoated metallic and ceramic femoral components, respectively. Silica/silane-coated ceramic components were stably fixed even under worst-case conditions. Loading under high flexion angles can induce interfacial tensile stress, which could promote early implant loosening. In conclusion, a silica/silane-coating layer on the femoral component increased their adhesive strength to bone cement. Thicker cement mantles (>2 mm) reduce adhesive strength of the femoral component and can increase the risk of cement break-off.

Associations of Age, BMI, and Years of Menstruation with Proximal Femur Strength in Chinese Postmenopausal Women: A Cross-Sectional Study.

PubMed

Kang, Huili; Chen, Yu-Ming; Han, Guiyuan; Huang, Hua; Chen, Wei-Qing; Wang, Xidan; Zhu, Ying-Ying; Xiao, Su-Mei

2016-01-23

This study aimed to elucidate the associations of age, BMI, and years of menstruation with proximal femur strength in Chinese postmenopausal women, which may improve the prediction of hip fracture risk. A cross-sectional study was conducted in 1322 Chinese postmenopausal women recruited from communities. DXA images were used to generate bone mineral density (BMD) and geometric parameters, including cross-sectional area (CSA), outer diameter (OD), cortical thickness (CT), section modulus (SM), buckling ratio (BR) at the narrow neck (NN), intertrochanter (IT), and femoral shaft (FS). Relationships of age, BMI, and years of menstruation with bone phenotypes were analyzed with the adjustment of height, age at menarche, total daily physical activity, education, smoking status, calcium tablet intake, etc. Age was associated with lower BMD, CSA, CT, SM, and higher BR (p < 0.05), which indicated a weaker bone strength at the proximal femur. BMI and years of menstruation had the positive relationships with proximal femur strength (p < 0.05). Further analyses showed that the ranges of absolute value of change slope per year, per BMI or per year of menstruation were 0.14%-1.34%, 0.20%-2.70%, and 0.16%-0.98%, respectively. These results supported that bone strength deteriorated with aging and enhanced with higher BMI and longer time of years of menstruation in Chinese postmenopausal women.

Associations of Age, BMI, and Years of Menstruation with Proximal Femur Strength in Chinese Postmenopausal Women: A Cross-Sectional Study

PubMed Central

Kang, Huili; Chen, Yu-Ming; Han, Guiyuan; Huang, Hua; Chen, Wei-Qing; Wang, Xidan; Zhu, Ying-Ying; Xiao, Su-Mei

2016-01-01

This study aimed to elucidate the associations of age, BMI, and years of menstruation with proximal femur strength in Chinese postmenopausal women, which may improve the prediction of hip fracture risk. A cross-sectional study was conducted in 1322 Chinese postmenopausal women recruited from communities. DXA images were used to generate bone mineral density (BMD) and geometric parameters, including cross-sectional area (CSA), outer diameter (OD), cortical thickness (CT), section modulus (SM), buckling ratio (BR) at the narrow neck (NN), intertrochanter (IT), and femoral shaft (FS). Relationships of age, BMI, and years of menstruation with bone phenotypes were analyzed with the adjustment of height, age at menarche, total daily physical activity, education, smoking status, calcium tablet intake, etc. Age was associated with lower BMD, CSA, CT, SM, and higher BR (p < 0.05), which indicated a weaker bone strength at the proximal femur. BMI and years of menstruation had the positive relationships with proximal femur strength (p < 0.05). Further analyses showed that the ranges of absolute value of change slope per year, per BMI or per year of menstruation were 0.14%–1.34%, 0.20%–2.70%, and 0.16%–0.98%, respectively. These results supported that bone strength deteriorated with aging and enhanced with higher BMI and longer time of years of menstruation in Chinese postmenopausal women. PMID:26805871

Regulation of bone remodeling by vitamin K2.

PubMed

Myneni, V D; Mezey, E

2017-11-01

All living tissues require essential nutrients such as amino acids, fatty acids, carbohydrates, minerals, vitamins, and water. The skeleton requires nutrients for development, maintaining bone mass and density. If the skeletal nutritional requirements are not met, the consequences can be quite severe. In recent years, there has been growing interest in promotion of bone health and inhibition of vascular calcification by vitamin K2. This vitamin regulates bone remodeling, an important process necessary to maintain adult bone. Bone remodeling involves removal of old or damaged bone by osteoclasts and its replacement by new bone formed by osteoblasts. The remodeling process is tightly regulated, when the balance between bone resorption and bone formation shifts to a net bone loss results in the development of osteoporosis in both men and women. In this review, we focus on our current understanding of the effects of vitamin K2 on bone cells and its role in prevention and treatment of osteoporosis. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Joint dysfunction and functional decline in middle age myostatin null mice.

PubMed

Guo, Wen; Miller, Andrew D; Pencina, Karol; Wong, Siu; Lee, Amanda; Yee, Michael; Toraldo, Gianluca; Jasuja, Ravi; Bhasin, Shalender

2016-02-01

Since its discovery as a potent inhibitor for muscle development, myostatin has been actively pursued as a drug target for age- and disease-related muscle loss. However, potential adverse effects of long-term myostatin deficiency have not been thoroughly investigated. We report herein that male myostatin null mice (mstn(-/-)), in spite of their greater muscle mass compared to wild-type (wt) mice, displayed more significant functional decline from young (3-6months) to middle age (12-15months) than age-matched wt mice, measured as gripping strength and treadmill endurance. Mstn(-/-) mice displayed markedly restricted ankle mobility and degenerative changes of the ankle joints, including disorganization of bone, tendon and peri-articular connective tissue, as well as synovial thickening with inflammatory cell infiltration. Messenger RNA expression of several pro-osteogenic genes was higher in the Achilles tendon-bone insertion in mstn(-/-) mice than wt mice, even at the neonatal age. At middle age, higher plasma concentrations of growth factors characteristic of excessive bone remodeling were found in mstn(-/-) mice than wt controls. These data collectively indicate that myostatin may play an important role in maintaining ankle and wrist joint health, possibly through negative regulation of the pro-osteogenic WNT/BMP pathway. Copyright © 2015 Elsevier Inc. All rights reserved.

Low-Temperature Additive Manufacturing of Biomimic Three-Dimensional Hydroxyapatite/Collagen Scaffolds for Bone Regeneration.

PubMed

Lin, Kai-Feng; He, Shu; Song, Yue; Wang, Chun-Mei; Gao, Yi; Li, Jun-Qin; Tang, Peng; Wang, Zheng; Bi, Long; Pei, Guo-Xian

2016-03-23

Low-temperature additive manufacturing (AM) holds promise for fabrication of three-dimensional (3D) scaffolds containing bioactive molecules and/or drugs. Due to the strict technical limitations of current approaches, few materials are suitable for printing at low temperature. Here, a low-temperature robocasting method was employed to print biomimic 3D scaffolds for bone regeneration using a routine collagen-hydroxyapatite (CHA) composite material, which is too viscous to be printed via normal 3D printing methods at low temperature. The CHA scaffolds had excellent 3D structure and maintained most raw material properties after printing. Compared to nonprinted scaffolds, printed scaffolds promoted bone marrow stromal cell proliferation and improved osteogenic outcome in vitro. In a rabbit femoral condyle defect model, the interconnecting pores within the printed scaffolds facilitated cell penetration and mineralization before the scaffolds degraded and enhanced repair, compared to nonprinted CHA scaffolds. Additionally, the optimal printing parameters for 3D CHA scaffolds were investigated; 600-μm-diameter rods were optimal in terms of moderate mechanical strength and better repair outcome in vivo. This low-temperature robocasting method could enable a variety of bioactive molecules to be incorporated into printed CHA materials and provides a method of bioprinting biomaterials without compromising their natural properties.

Compact, Controlled Resistance Exercise Device

NASA Technical Reports Server (NTRS)

Paulus, David C.; DeWitt, John K.; Reich, Alton J.; Shaw, James E.; Deaconu, Stelu S.

2011-01-01

Spaceflight leads to muscle and bone atrophy. Isoinertial (free-weight) exercises provide a sufficient stimulus to elicit increases in both muscle strength and bone mineral density in Earth-based studies. While exercise equipment is in use on the International Space Station for crewmember health maintenance, current devices are too large to place in a transport vehicle or small spacecraft. Therefore, a portable computer controlled resistance exercise device is being developed that is able to simulate the inertial loading experienced when lifting a mass on Earth. This portable device weighs less than 50 lb and can simulate the resistance of lifting and lowering up to 600 lb of free-weights. The objective is to allow crewmembers to perform resistance exercise with loads capable of maintaining muscle and bone health. The device is reconfigurable and allows for the performance of typical Earth-based free-weight exercises. Forces exerted, volume of work, range of motion, time-under-tension, and speed/ acceleration of movement are recorded and can be remotely monitored to track progress and modify individual protocols based on exercise session data. A performance evaluation will be completed and data will be presented that include ground-reaction force comparisons between the device and free-weight dead-lifts over a spectrum of resistance levels. Movement biomechanics will also be presented.

Cemented total knee replacement in 24 dogs: surgical technique, clinical results, and complications.

PubMed

Allen, Matthew J; Leone, Kendall A; Lamonte, Kimberly; Townsend, Katy L; Mann, Kenneth A

2009-07-01

To characterize the performance of cemented total knee replacement (TKR) in dogs. Preclinical research study. Skeletally mature, male Hounds (25-30 kg; n=24) with no preexisting joint pathology. Dogs had unilateral cemented TKR and were evaluated at 6, 12, 26, or 52 weeks (6 dogs/time point) by radiography, bone density analysis, visual gait assessment, and direct measurement of thigh circumference and stifle joint range of motion as indicators of functional recovery. At study end, the stability of the cemented tibial component was determined by destructive mechanical testing. Joint stability was excellent in 16 dogs (67%) and good in 8 dogs. None of the tibial components had evidence of migration or periprosthetic osteolysis whereas 1 femoral component was loose at 52 weeks. There was an early and significant decrease in tibial bone density, likely because of disuse of the operated limb. Dogs returned to full activity by 12 weeks. The tibial cement-bone interface maintained its strength over 52 weeks. Cement provides stable fixation of the tibial component in canine TKR. Cemented TKR yields adequate clinical function and stifle joint excursion in the dog. Clinical studies are needed to determine the long-term fate of cemented TKR implants, to assess the influence of implant design on implant fixation and wear, and to obtain objective functional data.

In vivo tibial stiffness is maintained by whole bone morphology and cross-sectional geometry in growing female mice

PubMed Central

Main, Russell P.; Lynch, Maureen E.; van der Meulen, Marjolein C.H.

2010-01-01

Whole bone morphology, cortical geometry, and tissue material properties modulate skeletal stresses and strains that in turn influence skeletal physiology and remodeling. Understanding how bone stiffness, the relationship between applied load and tissue strain, is regulated by developmental changes in bone structure and tissue material properties is important in implementing biophysical strategies for promoting healthy bone growth and preventing bone loss. The goal of this study was to relate developmental patterns of in vivo whole bone stiffness to whole bone morphology, cross-sectional geometry, and tissue properties using a mouse axial loading model. We measured in vivo tibial stiffness in three age groups (6wks, 10wks, 16wks old) of female C57Bl/6 mice during cyclic tibial compression. Tibial stiffness was then related to cortical geometry, longitudinal bone curvature, and tissue mineral density using microcomputed tomography (microCT). Tibial stiffness and the stresses induced by axial compression were generally maintained from 6 to 16wks of age. Growth-related increases in cortical cross-sectional geometry and longitudinal bone curvature had counteracting effects on induced bone stresses and, therefore, maintained tibial stiffness similarly with growth. Tissue mineral density increased slightly from 6 to 16wks of age, and although the effects of this increase on tibial stiffness were not directly measured, its role in the modulation of whole bone stiffness was likely minor over the age range examined. Thus, whole bone morphology, as characterized by longitudinal curvature, along with cortical geometry, plays an important role in modulating bone stiffness during development and should be considered when evaluating and designing in vivo loading studies and biophysical skeletal therapies. PMID:20673665

Pilot study of bone mineral density in breast cancer patients treated with adjuvant chemotherapy

NASA Technical Reports Server (NTRS)

Headley, J. A.; Theriault, R. L.; LeBlanc, A. D.; Vassilopoulou-Sellin, R.; Hortobagyi, G. N.

1998-01-01

The objective of this cross-sectional study was to determine lumbar spine bone mineral density (BMD) in breast cancer patients previously treated with adjuvant chemotherapy. Sixteen of 27 patients who received adjuvant chemotherapy became permanently amenorrheic as a result of chemotherapy. BMD was measured at the lumbar spine using dual energy X-ray absorptiometry (DEXA). Chemotherapy drugs and dosages along with a history of risk factors for reduced bone density including activity level, tobacco and/or alcohol use, metabolic bone disease, family history, and hormone exposure were identified. Results showed that women who became permanently amenorrheic as a result of chemotherapy had BMD 14% lower than women who maintained menses after chemotherapy. Chemotherapy-treated women who maintained ovarian function had normal BMD. This study suggests that women who have premature menopause as a result of chemotherapy for breast cancer are at increased risk of bone loss and may be at risk for early development of osteoporosis. Women who maintain menses do not appear to be at risk for accelerated trabecular bone loss.

[Preparation of nano-nacre artificial bone].

PubMed

Chen, Jian-ting; Tang, Yong-zhi; Zhang, Jian-gang; Wang, Jian-jun; Xiao, Ying

2008-12-01

To assess the improvements in the properties of nano-nacre artificial bone prepared on the basis of nacre/polylactide acid composite artificial bone and its potential for clinical use. The compound of nano-scale nacre powder and poly-D, L-lactide acid (PDLLA) was used to prepare the cylindrical hollow artificial bone, whose properties including raw material powder scale, pore size, porosity and biomechanical characteristics were compared with another artificial bone made of micron-scale nacre powder and PDLLA. Scanning electron microscope showed that the average particle size of the nano-nacre powder was 50.4-/+12.4 nm, and the average pore size of the artificial bone prepared using nano-nacre powder was 215.7-/+77.5 microm, as compared with the particle size of the micron-scale nacre powder of 5.0-/+3.0 microm and the pore size of the resultant artificial bone of 205.1-/+72.0 microm. The porosities of nano-nacre artificial bone and the micron-nacre artificial bone were (65.4-/+2.9)% and (53.4-/+2.2)%, respectively, and the two artificial bones had comparable compressive strength and Young's modulus, but the flexural strength of the nano-nacre artificial bone was lower than that of the micro-nacre artificial bone. The nano-nacre artificial bone allows better biodegradability and possesses appropriate pore size, porosity and biomechanical properties for use as a promising material in bone tissue engineering.

Freeze-Dried Platelet-Rich Plasma Accelerates Bone Union with Adequate Rigidity in Posterolateral Lumbar Fusion Surgery Model in Rats

NASA Astrophysics Data System (ADS)

Shiga, Yasuhiro; Orita, Sumihisa; Kubota, Go; Kamoda, Hiroto; Yamashita, Masaomi; Matsuura, Yusuke; Yamauchi, Kazuyo; Eguchi, Yawara; Suzuki, Miyako; Inage, Kazuhide; Sainoh, Takeshi; Sato, Jun; Fujimoto, Kazuki; Abe, Koki; Kanamoto, Hirohito; Inoue, Masahiro; Kinoshita, Hideyuki; Aoki, Yasuchika; Toyone, Tomoaki; Furuya, Takeo; Koda, Masao; Takahashi, Kazuhisa; Ohtori, Seiji

2016-11-01

Fresh platelet-rich plasma (PRP) accelerates bone union in rat model. However, fresh PRP has a short half-life. We suggested freeze-dried PRP (FD-PRP) prepared in advance and investigated its efficacy in vivo. Spinal posterolateral fusion was performed on 8-week-old male Sprague-Dawley rats divided into six groups based on the graft materials (n = 10 per group): sham control, artificial bone (A hydroxyapatite-collagen composite) -alone, autologous bone, artificial bone + fresh-PRP, artificial bone + FD-PRP preserved 8 weeks, and artificial bone + human recombinant bone morphogenetic protein 2 (BMP) as a positive control. At 4 and 8 weeks after the surgery, we investigated their bone union-related characteristics including amount of bone formation, histological characteristics of trabecular bone at remodeling site, and biomechanical strength on 3-point bending. Comparable radiological bone union was confirmed at 4 weeks after surgery in 80% of the FD-PRP groups, which was earlier than in other groups (p < 0.05). Histologically, the trabecular bone had thinner and more branches in the FD-PRP. Moreover, the biomechanical strength was comparable to that of autologous bone. FD-PRP accelerated bone union at a rate comparable to that of fresh PRP and BMP by remodeling the bone with thinner, more tangled, and rigid trabecular bone.

Freeze-Dried Platelet-Rich Plasma Accelerates Bone Union with Adequate Rigidity in Posterolateral Lumbar Fusion Surgery Model in Rats

PubMed Central

Shiga, Yasuhiro; Orita, Sumihisa; Kubota, Go; Kamoda, Hiroto; Yamashita, Masaomi; Matsuura, Yusuke; Yamauchi, Kazuyo; Eguchi, Yawara; Suzuki, Miyako; Inage, Kazuhide; Sainoh, Takeshi; Sato, Jun; Fujimoto, Kazuki; Abe, Koki; Kanamoto, Hirohito; Inoue, Masahiro; Kinoshita, Hideyuki; Aoki, Yasuchika; Toyone, Tomoaki; Furuya, Takeo; Koda, Masao; Takahashi, Kazuhisa; Ohtori, Seiji

2016-01-01

Fresh platelet-rich plasma (PRP) accelerates bone union in rat model. However, fresh PRP has a short half-life. We suggested freeze-dried PRP (FD-PRP) prepared in advance and investigated its efficacy in vivo. Spinal posterolateral fusion was performed on 8-week-old male Sprague-Dawley rats divided into six groups based on the graft materials (n = 10 per group): sham control, artificial bone (A hydroxyapatite–collagen composite) –alone, autologous bone, artificial bone + fresh-PRP, artificial bone + FD-PRP preserved 8 weeks, and artificial bone + human recombinant bone morphogenetic protein 2 (BMP) as a positive control. At 4 and 8 weeks after the surgery, we investigated their bone union–related characteristics including amount of bone formation, histological characteristics of trabecular bone at remodeling site, and biomechanical strength on 3-point bending. Comparable radiological bone union was confirmed at 4 weeks after surgery in 80% of the FD-PRP groups, which was earlier than in other groups (p < 0.05). Histologically, the trabecular bone had thinner and more branches in the FD-PRP. Moreover, the biomechanical strength was comparable to that of autologous bone. FD-PRP accelerated bone union at a rate comparable to that of fresh PRP and BMP by remodeling the bone with thinner, more tangled, and rigid trabecular bone. PMID:27833116

Biomechanical Comparisons of Pull Out Strengths After Pedicle Screw Augmentation with Hydroxyapatite, Calcium Phosphate, or Polymethylmethacrylate in the Cadaveric Spine.

PubMed

Yi, Seong; Rim, Dae-Cheol; Park, Seoung Woo; Murovic, Judith A; Lim, Jesse; Park, Jon

2015-06-01

In vertebrae with low bone mineral densities pull out strength is often poor, thus various substances have been used to fill screw holes before screw placement for corrective spine surgery. We performed biomechanical cadaveric studies to compare nonaugmented pedicle screws versus hydroxyapatite, calcium phosphate, or polymethylmethacrylate augmented pedicle screws for screw tightening torques and pull out strengths in spine procedures requiring bone screw insertion. Seven human cadaveric T10-L1 spines with 28 vertebral bodies were examined by x-ray to exclude bony abnormalities. Dual-energy x-ray absorptiometry scans evaluated bone mineral densities. Twenty of 28 vertebrae underwent ipsilateral fluoroscopic placement of 6-mm holes augmented with hydroxyapatite, calcium phosphate, or polymethylmethacrylate, followed by transpedicular screw placements. Controls were pedicle screw placements in the contralateral hemivertebrae without augmentation. All groups were evaluated for axial pull out strength using a biomechanical loading frame. Mean pedicle screw axial pull out strength compared with controls increased by 12.5% in hydroxyapatite augmented hemivertebrae (P = 0.600) and by 14.9% in calcium phosphate augmented hemivertebrae (P = 0.234), but the increase was not significant for either method. Pull out strength of polymethylmethacrylate versus hydroxyapatite augmented pedicle screws was 60.8% higher (P = 0.028). Hydroxyapatite and calcium phosphate augmentation in osteoporotic vertebrae showed a trend toward increased pedicle screw pull out strength versus controls. Pedicle screw pull out force of polymethylmethacrylate in the insertion stage was higher than that of hydroxyapatite. However, hydroxyapatite is likely a better clinical alternative to polymethylmethacrylate, as hydroxyapatite augmentation, unlike polymethylmethacrylate augmentation, stimulates bone growth and can be revised. Copyright © 2015 Elsevier Inc. All rights reserved.

Compression and flexural strength of bone cement mixed with blood.

PubMed

Tan, J H; Koh, B Th; Ramruttun, A K; Wang, W

2016-08-01

To assess the compression and flexural strength of bone cement mixed with 0 ml, 1 ml, or 2 ml of blood. High viscosity polymethyl methacrylate (PMMA) loaded with or without gentamicin was used. Blood was collected from total knee arthroplasty patients. In the same operating room, one pack of cement each was mixed with 0 ml (control), 1 ml, or 2 ml of blood for 1 minute during the dough phase. The dough was extruded into cylindrical and rectangular moulds for 20 minutes of setting, and then cured in phosphate buffered saline at 37±1ºC for 7 days. The samples were visually inspected for fractures and areas of weakness, and then scanned using microcomputed tomography. 48 gentamicin-loaded and 59 non-gentamicin-loaded samples mixed with 0 ml (control), 1 ml, or 2 ml of blood were randomised for flexural and compression strength testing; each group had at least 6 samples. In samples loaded with or without gentamicin, the flexural and compressive strength was highest in controls, followed by samples mixed with 1 ml or 2 ml of blood. In samples mixed with 2 ml of blood, the flexural strength fell below the standard of 50 MPa. In samples mixed with 2 ml of blood and all gentamicin-loaded samples, the compressive strength fell below the standard of 70 MPa. Microcomputed tomography revealed areas of voids and pores indicating the presence of laminations and partitions within. The biomechanical strength of PMMA contaminated with blood may decrease. Precautions such as saline lavage, pack drying the bone, change of gloves, and prompt insertion of the implant should be taken to prevent blood from contaminating bone cement.

Cortical and Trabecular Bone Microstructure Did Not Recover at Weight-Bearing Skeletal Sites and Progressively Deteriorated at Non-Weight-Bearing Sites During the Year Following International Space Station Missions.

PubMed

Vico, Laurence; van Rietbergen, Bert; Vilayphiou, Nicolas; Linossier, Marie-Thérèse; Locrelle, Hervé; Normand, Myriam; Zouch, Mohamed; Gerbaix, Maude; Bonnet, Nicolas; Novikov, Valery; Thomas, Thierry; Vassilieva, Galina

2017-10-01

Risk for premature osteoporosis is a major health concern in astronauts and cosmonauts; the reversibility of the bone lost at the weight-bearing bone sites is not established, although it is suspected to take longer than the mission length. The bone three-dimensional structure and strength that could be uniquely affected by weightlessness is currently unknown. Our objective is to evaluate bone mass, microarchitecture, and strength of weight-bearing and non-weight-bearing bone in 13 cosmonauts before and for 12 months after a 4-month to 6-month sojourn in the International Space Station (ISS). Standard and advanced evaluations of trabecular and cortical parameters were performed using high-resolution peripheral quantitative computed tomography. In particular, cortical analyses involved determination of the largest common volume of each successive individual scan to improve the precision of cortical porosity and density measurements. Bone resorption and formation serum markers, and markers reflecting osteocyte activity or periosteal metabolism (sclerostin, periostin) were evaluated. At the tibia, in addition to decreased bone mineral densities at cortical and trabecular compartments, a 4% decrease in cortical thickness and a 15% increase in cortical porosity were observed at landing. Cortical size and density subsequently recovered and serum periostin changes were associated with cortical recovery during the year after landing. However, tibial cortical porosity or trabecular bone failed to recover, resulting in compromised strength. The radius, preserved at landing, unexpectedly developed postflight fragility, from 3 months post-landing onward, particularly in its cortical structure. Remodeling markers, uncoupled in favor of bone resorption at landing, returned to preflight values within 6 months, then declined farther to lower than preflight values. Our findings highlight the need for specific protective measures not only during, but also after spaceflight, because of continuing uncertainties regarding skeletal recovery long after landing. © 2017 American Society for Bone and Mineral Research. © 2017 American Society for Bone and Mineral Research.

Femur-bending properties as influenced by gravity. V - Strength vs. calcium and gravity in rats exposed for 2 weeks

NASA Technical Reports Server (NTRS)

Wunder, Charles C.; Cook, Kenneth M.; Watkins, Stanley R.; Moressi, William J.

1987-01-01

The dependence of gravitationally related changes in femur bone strength on the comparable changes in calcium content was investigated in rats exposed to chronic simulations of altered gravity from the 28th to 42nd day of age. Zero G was simulated by harness suspension and 3 G by centrifugation. Bone strength (S) was determined by bending (using modified quasi-static cantilever bending methods and equipment described by Wunder et al., 1977 and 1979) and Ca content (C, by mass pct) determined by atomic absorption spectrometry; results were compared with data obtained on both normal and harnessed control animals at 1 G. Multiple regression showed significant dependence of S upon earth's gravity, independent from C, for which there was no significant coefficient of partial regression. It is suggested that the lack of S/C correlation might have been due to the fact that considerable fraction of the calcium in these young, developing bones has not yet crystallized into the hydroxyapatite which provides strength.

Detachment strength of human osteoblasts cultured on hydroxyapatite with various surface roughness. Contribution of integrin subunits.

PubMed

Kokkinos, Petros A; Koutsoukos, Petros G; Deligianni, Despina D

2012-06-01

Hydroxyapatite (HA) has been widely used as a bone substitute in dental, maxillofacial and orthopaedic surgery and as osteoconductive bone substitute or precoating of pedicle screws and cages in spine surgery. The aim of the present study was to investigate the osteoblastic adhesion strength on HA substrata with different surface topography and biochemistry (pre-adsorption of fibronectin) after blocking of specific integrin subunits with monoclonal antibodies. Stoichiometric HA was prepared by precipitation followed by ageing and characterized by SEM, EDX, powder XRD, Raman spectroscopy, TGA, and specific surface area analysis. Human bone marrow derived osteoblasts were cultured on HA disc-shaped substrata which were sintered and polished resulting in two surface roughness grades. For attachment evaluation, cells were incubated with monoclonal antibodies and seeded for 2 h on the substrata. Cell detachment strength was determined using a rotating disc device. Cell detachment strength was surface roughness, fibronectin preadsorption and intergin subunit sensitive.

Bone Mineral Density and Respiratory Muscle Strength in Male Individuals with Mental Retardation (with and without Down Syndrome)

ERIC Educational Resources Information Center

da Silva, Vinicius Zacarias Maldaner; Barros, Jonatas de Franca; de Azevedo, Monique; de Godoy, Jose Roberto Pimenta; Arena, Ross; Cipriano, Gerson, Jr.

2010-01-01

The purpose of this study was to assess the respiratory muscle strength (RMS) in individuals with mental retardation (MR), with or without Down Syndrome (DS), and its association with bone mineral density (BMD). Forty-five male individuals (15 with DS, 15 with mental retardation (MR) and 15 apparently healthy controls), aged 20-35, participated in…

Effect of green tea and Tai Chi on bone health in postmenopausal osteopenic women: a 6-month randomized placebo-controlled trial.

PubMed

Shen, C-L; Chyu, M-C; Yeh, J K; Zhang, Y; Pence, B C; Felton, C K; Brismée, J-M; Arjmandi, B H; Doctolero, S; Wang, J-S

2012-05-01

Postmenopausal women with osteopenia received green tea polyphenols (GTP) supplement and/or Tai Chi exercise for 6 months. Bone turnover biomarkers, calcium metabolism, and muscle strength were measured. This study showed that GTP supplementation and Tai Chi exercise increased bone formation biomarkers and improved bone turnover rate. Tai Chi exercise increased serum parathyroid hormone. GTP supplementation, Tai Chi exercise, and the combination of the two all improved muscle strength in postmenopausal women with osteopenia. This study evaluated the effect of GTP supplementation and Tai Chi (TC) exercise on serum markers of bone turnover (bone-specific alkaline phosphatase, BAP, and tartrate-resistant acid phosphatase, TRAP), calcium metabolism, and muscle strength in postmenopausal osteopenic women. One hundred and seventy-one postmenopausal osteopenic women were randomly assigned to four groups: (1) placebo (500 mg starch/day), (2) GTP (500 mg GTP/day), (3) placebo + TC (placebo plus TC training at 60 min/session, three sessions/week), and (4) GTP + TC (GTP plus TC training). Overnight fasting blood and urine samples were collected at baseline, 1, 3, and 6 months for biomarker analyses. Muscle strength was evaluated at baseline, 3, and 6 months. One hundred and fifty subjects completed the 6-month study. Significant increases in BAP level due to GTP intake (at 1 month) and TC (at 3 months) were observed. Significant increases in the change of BAP/TRAP ratio due to GTP (at 3 months) and TC (at 6 months) were also observed. Significant main effect of TC on the elevation in serum parathyroid hormone level was observed at 1 and 3 months. At 6 months, muscle strength significantly improved due to GTP, TC, and GTP + TC interventions. Neither GTP nor TC affected serum TRAP, serum and urinary calcium, and inorganic phosphate. In summary, GTP supplementation and TC exercise increased BAP and improved BAP/TRAP ratio. TC exercise increased serum parathyroid hormone. GTP supplementation, TC exercise, and the combination of the two all improved muscle strength in postmenopausal women with osteopenia.

Polarization in Raman spectroscopy helps explain bone brittleness in genetic mouse models

NASA Astrophysics Data System (ADS)

Makowski, Alexander J.; Pence, Isaac J.; Uppuganti, Sasidhar; Zein-Sabatto, Ahbid; Huszagh, Meredith C.; Mahadevan-Jansen, Anita; Nyman, Jeffry S.

2014-11-01

Raman spectroscopy (RS) has been extensively used to characterize bone composition. However, the link between bone biomechanics and RS measures is not well established. Here, we leveraged the sensitivity of RS polarization to organization, thereby assessing whether RS can explain differences in bone toughness in genetic mouse models for which traditional RS peak ratios are not informative. In the selected mutant mice-activating transcription factor 4 (ATF4) or matrix metalloproteinase 9 (MMP9) knock-outs-toughness is reduced but differences in bone strength do not exist between knock-out and corresponding wild-type controls. To incorporate differences in the RS of bone occurring at peak shoulders, a multivariate approach was used. Full spectrum principal components analysis of two paired, orthogonal bone orientations (relative to laser polarization) improved genotype classification and correlation to bone toughness when compared to traditional peak ratios. When applied to femurs from wild-type mice at 8 and 20 weeks of age, the principal components of orthogonal bone orientations improved age classification but not the explanation of the maturation-related increase in strength. Overall, increasing polarization information by collecting spectra from two bone orientations improves the ability of multivariate RS to explain variance in bone toughness, likely due to polarization sensitivity to organizational changes in both mineral and collagen.

Sprint Interval Training Induces A Sexual Dimorphism but does not Improve Peak Bone Mass in Young and Healthy Mice

PubMed Central

Koenen, Kathrin; Knepper, Isabell; Klodt, Madlen; Osterberg, Anja; Stratos, Ioannis; Mittlmeier, Thomas; Histing, Tina; Menger, Michael D.; Vollmar, Brigitte; Bruhn, Sven; Müller-Hilke, Brigitte

2017-01-01

Elevated peak bone mass in early adulthood reduces the risk for osteoporotic fractures at old age. As sports participation has been correlated with elevated peak bone masses, we aimed to establish a training program that would efficiently stimulate bone accrual in healthy young mice. We combined voluntary treadmill running with sprint interval training modalities that were tailored to the individual performance limits and were of either high or intermediate intensity. Adolescent male and female STR/ort mice underwent 8 weeks of training before the hind legs were analyzed for cortical and trabecular bone parameters and biomechanical strength. Sprint interval training led to increased running speeds, confirming an efficient training. However, males and females responded differently. The males improved their running speeds in response to intermediate intensities only and accrued cortical bone at the expense of mechanical strength. High training intensities induced a significant loss of trabecular bone. The female bones showed neither adverse nor beneficial effects in response to either training intensities. Speculations about the failure to improve geometric alongside mechanical bone properties include the possibility that our training lacked sufficient axial loading, that high cardio-vascular strains adversely affect bone growth and that there are physiological limits to bone accrual. PMID:28303909

Alcohol and bone: review of dose effects and mechanisms.

PubMed

Maurel, D B; Boisseau, N; Benhamou, C L; Jaffre, C

2012-01-01

Alcohol is widely consumed across the world. It is consumed in both social and cultural settings. Until recently, two types of alcohol consumption were recognized: heavy chronic alcohol consumption or light consumption. Today, there is a new pattern of consumption among teenagers and young adults namely: binge drinking. Heavy alcohol consumption is detrimental to many organs and tissues, including bones, and is known to induce secondary osteoporosis. Some studies, however, have reported benefits from light alcohol consumption on bone parameters. To date, little is known regarding the effects of binge drinking on bone health. Here, we review the effects of three different means of alcohol consumption: light, heavy, and binge drinking. We also review the detailed literature on the different mechanisms by which alcohol intake may decrease bone mass and strength. The effects of alcohol on bone are thought to be both direct and indirect. The decrease in bone mass and strength following alcohol consumption is mainly due to a bone remodeling imbalance, with a predominant decrease in bone formation. Recent studies, however, have reported new mechanisms by which alcohol may act on bone remodeling, including osteocyte apoptosis, oxidative stress, and Wnt signalling pathway modulation. The roles of reduced total fat mass, increased lipid content in bone marrow, and a hypoleptinemia are also discussed.

Vibration therapy: clinical applications in bone

PubMed Central

Thompson, William R.; Yen, Sherwin S.; Rubin, Janet

2015-01-01

Purpose of review The musculoskeletal system is largely regulated through dynamic physical activity and is compromised by cessation of physical loading. There is a need to recreate the anabolic effects of loading on the musculoskeletal system, especially in frail individuals who cannot exercise. Vibration therapy is designed to be a nonpharmacological analogue of physical activity, with an intention to promote bone and muscle strength. Recent findings Animal and human studies suggest that high-frequency, low-magnitude vibration therapy improves bone strength by increasing bone formation and decreasing bone resorption. There is also evidence that vibration therapy is useful in treating sarcopenia, which confounds skeletal fragility and fall risk in aging. Enhancement of skeletal and muscle strength involves regulating the differentiation of mesenchymal stem cells to build these tissues; mesenchymal stem cell lineage allocation is positively promoted by vibration signals. Summary Vibration therapy may be useful as a primary treatment as well as an adjunct to both physical and pharmacological treatments, but future studies must pay close attention to compliance and dosing patterns, and importantly, the vibration signal, be it low-intensity vibration (<1g) appropriate for treatment of frail individuals or high-intensity vibration (>1g) marketed as a training exercise. PMID:25354044

Impact of physical activity, sedentary behaviour and muscle strength on bone stiffness in 2-10-year-old children-cross-sectional results from the IDEFICS study.

PubMed

Herrmann, Diana; Buck, Christoph; Sioen, Isabelle; Kouride, Yiannis; Marild, Staffan; Molnár, Dénes; Mouratidou, Theodora; Pitsiladis, Yannis; Russo, Paola; Veidebaum, Toomas; Ahrens, Wolfgang

2015-09-17

Physical activity (PA), weight-bearing exercises (WBE) and muscle strength contribute to skeletal development, while sedentary behaviour (SB) adversely affects bone health. Previous studies examined the isolated effect of PA, SB or muscle strength on bone health, which was usually assessed by x-ray methods, in children. Little is known about the combined effects of these factors on bone stiffness (SI) assessed by quantitative ultrasound. We investigated the joint association of PA, SB and muscle strength on SI in children. In 1512 preschool (2- < 6 years) and 2953 school children (6-10 years), data on calcaneal SI as well as on accelerometer-based sedentary time (SED), light (LPA), moderate (MPA) and vigorous PA (VPA) were available. Parents reported sports (WBE versus no WBE), leisure time PA and screen time of their children. Jumping distance and handgrip strength served as indicators for muscle strength. The association of PA, SB and muscle strength with SI was estimated by multivariate linear regression, stratified by age group. Models were adjusted for age, sex, country, fat-free mass, daylight duration, consumption of dairy products and PA, or respectively SB. Mean SI was similar in preschool (79.5 ± 15.0) and school children (81.3 ± 12.1). In both age groups, an additional 10 min/day in MPA or VPA increased the SI on average by 1 or 2%, respectively (p ≤ .05). The negative association of SED with SI decreased after controlling for MVPA. LPA was not associated with SI. Furthermore, participation in WBE led to a 3 and 2% higher SI in preschool (p = 0.003) and school children (p < .001), respectively. Although muscle strength significantly contributed to SI, it did not affect the associations of PA with SI. In contrast to objectively assessed PA, reported leisure time PA and screen time showed no remarkable association with SI. This study suggests that already an additional 10 min/day of MPA or VPA or the participation in WBE may result in a relevant increase in SI in children, taking muscle strength and SB into account. Our results support the importance of assessing accelerometer-based PA in large-scale studies. This may be important when deriving dose-response relationships between PA and bone health in children.

The effects of a 6-month resistance training and dried plum consumption intervention on strength, body composition, blood markers of bone turnover, and inflammation in breast cancer survivors.

PubMed

Simonavice, Emily; Liu, Pei-Yang; Ilich, Jasminka Z; Kim, Jeong-Su; Arjmandi, Bahram; Panton, Lynn B

2014-06-01

The purpose of this study was to examine the effects of resistance training (RT) and dried plum (DP) consumption on strength, body composition, blood markers of bone, and inflammation in breast cancer survivors (BCS). Twenty-three BCS (RT, n = 12; RT+DP, n = 11), aged 64 ± 7 years, were evaluated at baseline and after 6 months of intervention on the following: muscular strength (chest press and leg extension) via 1-repetition maximums (1RMs); body composition, specifically bone mineral density (BMD) by dual energy X-ray absorptiometry; biochemical markers of bone turnover (bone-specific alkaline phosphatase (BAP), tartrate resistant acid phosphatase (TRAP-5b)); and inflammation (C-reactive protein (CRP)). Target RT prescription was 2 days/week of 10 exercises, including 2 sets of 8-12 repetitions at ∼60%-80% of 1RM. RT+DP also consumed 90 g of DP daily. There were no baseline differences between groups or any group-by-time interactions for any of the variables. BCS increased upper (p < 0.05) (RT: 64 ± 14 to 80 ± 17 kg; RT+DP: 72 ± 23 to 91 ± 20 kg) and lower (p < 0.05) (RT: 69 ± 20 to 87 ± 28 kg; RT+DP: 78 ± 19 to 100 ± 21 kg) body strength. Body composition and BMD improvements were not observed. TRAP-5b decreased in the RT group (p < 0.05) (4.55 ± 1.57 to 4.04 ± 1.63 U/L) and the RT+DP group (p = 0.07) (5.10 ± 2.75 to 4.27 ± 2.03 U/L). Changes in BAP and CRP were not observed. RT was effective for improving biochemical markers of bone turnover and muscular strength in BCS. A longer and higher intensity intervention may be needed to reveal the true effects of RT and DP on body composition and biochemical markers of inflammation.

Dietary boron does not affect tooth strength, micro-hardness, and density, but affects tooth mineral composition and alveolar bone mineral density in rabbits fed a high-energy diet.

PubMed

Hakki, Sema S; SiddikMalkoc; Dundar, Niyazi; Kayis, Seyit Ali; Hakki, Erdogan E; Hamurcu, Mehmet; Baspinar, Nuri; Basoglu, Abdullah; Nielsen, Forrest H; Götz, Werner

2015-01-01

The objective of this study was to determine whether dietary boron (B) affects the strength, density and mineral composition of teeth and mineral density of alveolar bone in rabbits with apparent obesity induced by a high-energy diet. Sixty female, 8-month-old, New Zealand rabbits were randomly assigned for 7 months into five groups as follows: (1) control 1, fed alfalfa hay only (5.91 MJ/kg and 57.5 mg B/kg); (2) control 2, high energy diet (11.76 MJ and 3.88 mg B/kg); (3) B10, high energy diet + 10 mg B gavage/kg body weight/96 h; (4) B30, high energy diet + 30 mg B gavage/kg body weight/96 h; (5) B50, high energy diet + 50 mg B gavage/kg body weight/96 h. Maxillary incisor teeth of the rabbits were evaluated for compression strength, mineral composition, and micro-hardness. Enamel, dentin, cementum and pulp tissue were examined histologically. Mineral densities of the incisor teeth and surrounding alveolar bone were determined by using micro-CT. When compared to controls, the different boron treatments did not significantly affect compression strength, and micro-hardness of the teeth, although the B content of teeth increased in a dose-dependent manner. Compared to control 1, B50 teeth had decreased phosphorus (P) concentrations. Histological examination revealed that teeth structure (shape and thickness of the enamel, dentin, cementum and pulp) was similar in the B-treated and control rabbits. Micro CT evaluation revealed greater alveolar bone mineral density in B10 and B30 groups than in controls. Alveolar bone density of the B50 group was not different than the controls. Although the B treatments did not affect teeth structure, strength, mineral density and micro-hardness, increasing B intake altered the mineral composition of teeth, and, in moderate amounts, had beneficial effects on surrounding alveolar bone.

Geometric indices of bone strength are associated with physical activity and dietary calcium intake in healthy older women.

PubMed

Nurzenski, Michelle K; Briffa, N Kathryn; Price, Roger I; Khoo, Benjamin C C; Devine, Amanda; Beck, Thomas J; Prince, Richard L

2007-03-01

A population-based study on 1008 postmenopausal women identified that the 24% of women achieving high levels of PA and CI had 3.4-4.4% higher femoral bone strength in axial compression and 1.7-5.2% in bending than those achieving low levels, indicating that lifestyle factors influence bone strength in the proximal femur. Extensive research has shown that increased physical activity (PA) and calcium intake (CI) decrease the rate of bone loss; however, there is little research on how these lifestyle variables affect bone geometry. This study was designed to investigate the effects of modifiable lifestyle variables, habitual PA and dietary CI, on femoral geometry in older women. Femoral geometry, habitual PA, and dietary CI were measured in a population-based sample of 1008 women (median age+/-interquartile range, 75+/-4years) enrolled in a randomized controlled trial (RCT) of calcium supplementation. Baseline PA and CI were assessed by validated questionnaires, and 1-year DXA scans (Hologic 4500A) were analyzed using the hip structural analysis technique. Section modulus (Z), an index of bending strength, cross-sectional area (CSA), an index of axial compression strength, subperiosteal width (SPW), and centroid position, the position of the center of mass, were measured at the femoral neck (NN), intertrochanter (IT), and femoral shaft (FS) sites. These data were divided into tertiles of PA and CI, and the results were compared using analysis of covariance (ANCOVA), with corrections for age, height, weight, and treatment (calcium/placebo). PA showed a significant dose-response effect on CSA all hip sites (p<0.03) and Z at the narrow neck and intertrochanter sites (p<0.02). For CI, there was a dose-response effect for centroid position at the intertrochanter (p=0.03). These effects were additive, such that the women (n=240) with PA in excess of 65.5 kcal/day and CI in excess of 1039 mg/day had significantly greater CSA (NN, 4.4%; IT, 4.3%; FS, 3.4%) and Z (NN, 3.9%; IT, 5.2%). These data show a favorable association between PA and aspects of bone structural geometry consistent with better bone strength. Association between CI and bone structure was only evident in 1 of 15 variables tested. However, there was evidence that there may be additive effects, whereby women with high levels of PA and CI in excess of 1039 mg/day had significantly greater CSA (NN, 0.4%; FS, 2.1%) and Z (IT, 3.0%) than women with high PA but low CI. These data show that current public health guidelines for PA and dietary CI are not inappropriate where bone structure is the health component of interest.