Sit-To-Stand Biomechanics Before and After Total Hip Arthroplasty

PubMed Central

Abujaber, Sumayeh B.; Marmon, Adam R.; Pozzi, Federico; Rubano, James J.; Zeni, Joseph A.

2015-01-01

The purpose of this study was to evaluate changes in movement patterns during a sit-to-stand (STS) task before and after total hip arthroplasty (THA), and to compare biomechanical outcomes after THA to a control group. Forty-five subjects who underwent THA and twenty-three healthy control subjects participated in three-dimensional motion analysis. Pre-operatively, subjects exhibited inter-limb movement asymmetries with lower vertical ground reaction force (VGRF) and smaller moments on the operated limb. Although there were significant improvements in movement symmetry 3 months after THA, patients continued to demonstrate lower VGRF and smaller moments on the operated limb compared to non-operated and to control limbs. Future studies should identify the contributions of physical impairments and the influence of surgical approach on STS biomechanics. PMID:26117068

Restoring Segmental Biomechanics Through Nucleus Augmentation: An In Vitro Study.

PubMed

Pelletier, Matthew H; Cohen, Charles S; Ducheyne, Paul; Walsh, William R

2016-12-01

In vitro biomechanical laboratory study. The purpose of this study is to evaluate a mechanical treatment to create a degenerative motion segment and the ability of nucleus augmentation to restore biomechanics. In cases with an intact annulus fibrosus, the replacement or augmentation of the nucleus pulposus alone may provide a less invasive option to restore normal biomechanics and disk height when compared with spinal fusion or total disk replacement. Laboratory testing allows these changes to be fully characterized. However, without preexisting pathology, nucleus augmentation therapies are difficult to evaluate in vitro. The present study evaluated pure moment bending and compressive biomechanics in 3 states (n=6): (1) intact, (2) after creep loading and nucleus disruption to induce degenerative biomechanical changes, and (3) after nucleus augmentation through an injectable polymer (DiscCell). Neutral zone and ROM were increased in all modes of bending after the degenerative treatment. The most sensitive mode of bending was lateral bending, with intact ROM (20.0±2.9 degrees) increased to 22.3±2.6 degrees after degenerative treatment and reduced to 18.4±1.6 degrees after injection of the polymer. All bending ROM and NZ changes induced by the degenerative treatment were reversed by nucleus augmentation. This material was shown to be effective at altering motion segment biomechanics and restoring disk height during time zero tests. This technique may provide a model to examine the time zero performance of a nucleus augmentation device/material.

Biomechanical and Psychological Analysis of High School, Intercollegiate, and Elite Long-Distance Runners

ERIC Educational Resources Information Center

Solorio, Claribel; Hickey, Ann

2015-01-01

It is undeniable that efficiency and mentality are crucial to achieving optimal athletic performance during competition. However, development of psychological skills is often neglected, particularly in lower levels of competition. The purpose of this study was to analyze and compare the biomechanical efficiency and psychological skills use among…

Biomechanical comparison between suture anchor and transtibial pull-out repair for posterior medial meniscus root tears.

PubMed

Feucht, Matthias J; Grande, Eduardo; Brunhuber, Johannes; Rosenstiel, Nikolaus; Burgkart, Rainer; Imhoff, Andreas B; Braun, Sepp

2014-01-01

Posterior medial meniscus root (PMMR) tears have a serious effect on knee joint biomechanics. Currently used techniques for refixation of the PMMR include the transtibial pull-out repair (TP) and suture anchor repair (SA). These techniques have not been compared biomechanically. The SA technique provides superior biomechanical properties compared with the TP technique. Controlled laboratory study. A total of 24 fresh-frozen porcine tibiae with attached intact medial menisci were used. The specimens were randomly assigned to 3 groups (8 specimens each). A standardized PMMR tear was created in 16 specimens. Refixation of the PMMR was performed by either the TP or SA technique. The native PMMR was left intact in 8 specimens. All specimens were subjected to cyclic loading followed by load-to-failure testing. Displacement after 100, 500, and 1000 cycles; maximum load to failure; stiffness; and displacement at failure were recorded. Both repair techniques showed a significantly higher displacement during cyclic loading and a significantly lower maximum load and stiffness during load-to-failure testing compared with the native PMMR (P < .05). The SA technique showed a significantly lower displacement after 100, 500, and 1000 cycles (P < .001) and a significantly higher stiffness (P = .016) compared with the TP technique. Maximum load did not differ significantly between the SA and TP techniques (P = .027, Bonferroni adjustment). No significant difference between the 3 groups was observed for displacement at failure (P > .05). The SA technique provided superior biomechanical properties compared with the TP technique. Both repair techniques did not reach the strength of the native PMMR. The favorable biomechanical properties of the SA technique might be beneficial for healing of the repaired PMMR and restoration of meniscus function. Because of inferior time zero stability compared with the native PMMR, slow rehabilitation is recommended after meniscus root repair.

Canine stifle joint biomechanics associated with tibial plateau leveling osteotomy predicted by use of a computer model.

PubMed

Brown, Nathan P; Bertocci, Gina E; Marcellin-Little, Denis J

2014-07-01

To evaluate effects of tibial plateau leveling osteotomy (TPLO) on canine stifle joint biomechanics in a cranial cruciate ligament (CrCL)-deficient stifle joint by use of a 3-D computer model simulating the stance phase of gait and to compare biomechanics in TPLO-managed, CrCL-intact, and CrCL-deficient stifle joints. Computer simulations of the pelvic limb of a Golden Retriever. A previously developed computer model of the canine pelvic limb was used to simulate TPLO stabilization to achieve a tibial plateau angle (TPA) of 5° (baseline value) in a CrCL-deficient stifle joint. Sensitivity analysis was conducted for tibial fragment rotation of 13° to -3°. Ligament loads, relative tibial translation, and relative tibial rotation were determined and compared with values for CrCL-intact and CrCL-deficient stifle joints. TPLO with a 5° TPA converted cranial tibial translation to caudal tibial translation and increased loads placed on the remaining stifle joint ligaments, compared with results for a CrCL-intact stifle joint. Lateral collateral ligament load was similar, medial collateral ligament load increased, and caudal cruciate ligament load decreased after TPLO, compared with loads for a CrCL-deficient stifle joint. Relative tibial rotation after TPLO was similar to that of a CrCL-deficient stifle joint. Stifle joint biomechanics were affected by TPLO fragment rotation. In the model, stifle joint biomechanics were partially improved after TPLO, compared with CrCL-deficient stifle joint biomechanics, but TPLO did not fully restore CrCL-intact stifle joint biomechanics. Overrotation of the tibial fragment negatively influenced stifle joint biomechanics by increasing caudal tibial translation.

Biomechanics of oral mucosa

PubMed Central

Chen, Junning; Ahmad, Rohana; Li, Wei; Swain, Michael; Li, Qing

2015-01-01

The prevalence of prosthodontic treatment has been well recognized, and the need is continuously increasing with the ageing population. While the oral mucosa plays a critical role in the treatment outcome, the associated biomechanics is not yet fully understood. Using the literature available, this paper provides a critical review on four aspects of mucosal biomechanics, including static, dynamic, volumetric and interactive responses, which are interpreted by its elasticity, viscosity/permeability, apparent Poisson's ratio and friction coefficient, respectively. Both empirical studies and numerical models are analysed and compared to gain anatomical and physiological insights. Furthermore, the clinical applications of such biomechanical knowledge on the mucosa are explored to address some critical concerns, including stimuli for tissue remodelling (interstitial hydrostatic pressure), pressure–pain thresholds, tissue displaceability and residual bone resorption. Through this review, the state of the art in mucosal biomechanics and their clinical implications are discussed for future research interests, including clinical applications, computational modelling, design optimization and prosthetic fabrication. PMID:26224566

The effects of floor incline on lower extremity biomechanics during unilateral landing from a jump in dancers.

PubMed

Pappas, Evangelos; Orishimo, Karl F; Kremenic, Ian; Liederbach, Marijeanne; Hagins, Marshall

2012-05-01

Retrospective studies have suggested that dancers performing on inclined ("raked") stages have increased injury risk. One study suggests that biomechanical differences exist between flat and inclined surfaces during bilateral landings; however, no studies have examined whether such differences exist during unilateral landings. In addition, little is known regarding potential gender differences in landing mechanics of dancers. Professional dancers (N = 41; 14 male, 27 female) performed unilateral drop jumps from a 30 cm platform onto flat and inclined surfaces while extremity joint angles and moments were identified and analyzed. There were significant joint angle and moment effects due to the inclined flooring. Women had significantly decreased peak ankle dorsiflexion and hip adduction moment compared with men. Findings of the current study suggest that unilateral landings on inclined stages create measurable changes in lower extremity biomechanical variables. These findings provide a preliminary biomechanical rationale for differences in injury rates found in observational studies of raked stages.

Total knee arthroplasty with computer-assisted navigation more closely replicates normal knee biomechanics than conventional surgery.

PubMed

McClelland, Jodie A; Webster, Kate E; Ramteke, Alankar A; Feller, Julian A

2017-06-01

Computer-assisted navigation in total knee arthroplasty (TKA) reduces variability and may improve accuracy in the postoperative static alignment. The effect of navigation on alignment and biomechanics during more dynamic movements has not been investigated. This study compared knee biomechanics during level walking of 121 participants: 39 with conventional TKA, 42 with computer-assisted navigation TKA and 40 unimpaired control participants. Standing lower-limb alignment was significantly closer to ideal in participants with navigation TKA. During gait, when differences in walking speed were accounted for, participants with conventional TKA had less knee flexion during stance and swing than controls (P<0.01), but there were no differences between participants with navigation TKA and controls for the same variables. Both groups of participants with TKA had lower knee adduction moments than controls (P<0.01). In summary, there were fewer differences in the biomechanics of computer-assisted navigation TKA patients compared to controls than for patients with conventional TKA. Computer-assisted navigation TKA may restore biomechanics during walking that are closer to normal than conventional TKA. Copyright © 2017 Elsevier B.V. All rights reserved.

Biomechanical performance of baseball pitchers with a history of ulnar collateral ligament reconstruction.

PubMed

Fleisig, Glenn S; Leddon, Charles E; Laughlin, Walter A; Ciccotti, Michael G; Mandelbaum, Bert R; Aune, Kyle T; Escamilla, Rafael F; MacLeod, Toran D; Andrews, James R

2015-05-01

A relatively high number of active professional baseball pitchers have a history of ulnar collateral ligament reconstruction (UCLr) on their throwing elbow. Controversy exists in the literature about whether professional baseball pitchers regain optimal performance after return from UCLr. It has been suggested that pitchers may have different biomechanics after UCLr, but this has not been previously tested. It was hypothesized that, compared with a control group without a history of UCLr, professional pitchers with a history of UCLr would have (1) significantly different throwing elbow and shoulder biomechanics; (2) a shortened stride, insufficient trunk forward tilt, and excessive shoulder horizontal adduction, characteristics associated with "holding back" or being tentative; (3) late shoulder rotation; and (4) improper shoulder abduction and trunk lateral tilt. Controlled laboratory study. A total of 80 active minor league baseball pitchers (and their 8 Major League Baseball organizations) agreed to participate in this study. Participants included 40 pitchers with a history of UCLr and a matched control group of 40 pitchers with no history of elbow or shoulder surgery. Passive ranges of motion were measured for each pitcher's elbows and shoulders, and then 23 reflective markers were attached to his body. The pitcher took as many warm-up pitches as desired and then threw 10 full-effort fastballs for data collection. Ball speed was recorded with a radar gun. The reflective markers were tracked with a 10-camera, 240-Hz automated motion analysis system. Eleven biomechanical parameters were computed for each pitch and then averaged for each participant. Demographic, range of motion, and biomechanical parameters were compared between the UCLr group and the control group by use of Student t tests (significance set at P<.05). All hypotheses were rejected, as there were no differences in pitching biomechanics between the UCLr group and the control group. There were also no differences in passive range of motion between the 2 groups. Compared with a control group, active professional pitchers with a history of UCLr displayed no significant differences in shoulder and elbow passive range of motion and no significant differences in elbow and shoulder biomechanics. Clinical studies have previously shown that 10% to 33% of professional pitchers do not return to their preinjury level; however, the current study showed that those pitchers who successfully return to professional baseball after UCLr pitch with biomechanics similar to that of noninjured professionals. © 2015 The Author(s).

Influence of hyperbaric oxygen on biomechanics and structural bone matrix in type 1 diabetes mellitus rats.

PubMed

Limirio, Pedro Henrique Justino Oliveira; da Rocha Junior, Huberth Alexandre; Morais, Richarlisson Borges de; Hiraki, Karen Renata Nakamura; Balbi, Ana Paula Coelho; Soares, Priscilla Barbosa Ferreira; Dechichi, Paula

2018-01-01

The aim of this study was to evaluate the biomechanics and structural bone matrix in diabetic rats subjected to hyperbaric oxygen therapy (HBO). Twenty-four male rats were divided into the following groups: Control; Control + HBO; Diabetic, and Diabetic + HBO. Diabetes was induced with streptozotocin (STZ) in the diabetic Groups. After 30 days, HBO was performed every 48h in HBO groups and all animals were euthanized 60 days after diabetic induction. The femur was submitted to a biomechanical (maximum strength, energy-to-failure and stiffness) and Attenuated Total Reflectance Fourier transform infrared (ATR-FTIR) analyses (crosslink ratio, crystallinity index, matrix-to-mineral ratio: Amide I + II/Hydroxyapatite (M:MI) and Amide III + Collagen/HA (M:MIII)). In biomechanical analysis, diabetic animals showed lower values of maximum strength, energy and stiffness than non-diabetic animals. However, structural strength and stiffness were increased in groups with HBO compared with non-HBO. ATR-FTIR analysis showed decreased collagen maturity in the ratio of crosslink peaks in diabetic compared with the other groups. The bone from the diabetic groups showed decreased crystallinity compared with non-diabetic groups. M:MI showed no statistical difference between groups. However, M:MIII showed an increased matrix mineral ratio in diabetic+HBO and control+HBO compared with control and diabetic groups. Correlations between mechanical and ATR-FTIR analyses showed significant positive correlation between collagen maturity and stiffness. Diabetes decreased collagen maturation and the mineral deposition process, thus reducing biomechanical properties. Moreover, the study showed that HBO improved crosslink maturation and increased maximum strength and stiffness in the femur of T1DM animals.

Knee movement patterns of injured and uninjured adolescent basketball players when landing from a jump: A case-control study

PubMed Central

Louw, Quinette; Grimmer, Karen; Vaughan, Christopher

2006-01-01

Background A common knee injury mechanism sustained during basketball is landing badly from a jump. Landing is a complex task and requires good coordination, dynamic muscle control and flexibility. For adolescents whose coordination and motor control has not fully matured, landing badly from a jump can present a significant risk for injury. There is currently limited biomechanical information regarding the lower limb kinetics of adolescents when jumping, specifically regarding jump kinematics comparing injured with uninjured adolescents. This study reports on an investigation of biomechanical differences in landing patterns of uninjured and injured adolescent basketball players. Methods A matched case-control study design was employed. Twenty-two basketball players aged 14–16 years participated in the study: eleven previously knee-injured and eleven uninjured players matched with cases for age, gender, weight, height and years of play, and playing for the same club. Six high-speed, three-dimensional Vicon 370 cameras (120 Hz), Vicon biomechanical software and SAS Version 8 software were employed to analyse landing patterns when subjects performed a "jump shot". Linear correlations determined functional relationships between the biomechanical performance of lower limb joints, and paired t-tests determined differences between the normalised peak biomechanical parameters. Results The average peak vertical ground reaction forces between the cases and controls were similar. The average peak ground reaction forces between the cases and controls were moderately correlated (r = -0.47). The control (uninjured) players had significantly greater hip and knee flexion angles and significantly greater eccentric activity on landing than the uninjured cases (p < 0.01). Conclusion The findings of the study indicate that players with a history of knee injuries had biomechanically compromised landing techniques when compared with uninjured players matched for gender, age and club. Descriptions (norms) of expected levels of knee control, proprioceptive acuity and eccentric strength relative to landing from a jump, at different ages and physical developmental stages, would assist clinicians and coaches to identify players with inappropriate knee performance comparable to their age or developmental stage. PMID:16522210

Biomechanical Stability of Dental Implants in Augmented Maxillary Sites: Results of a Randomized Clinical Study with Four Different Biomaterials and PRF and a Biological View on Guided Bone Regeneration

PubMed Central

Angelo, Troedhan; Marcel, Wainwright; Andreas, Kurrek; Izabela, Schlichting

2015-01-01

Introduction. Bone regenerates mainly by periosteal and endosteal humoral and cellular activity, which is given only little concern in surgical techniques and choice of bone grafts for guided bone regeneration. This study investigates on a clinical level the biomechanical stability of augmented sites in maxillary bone when a new class of moldable, self-hardening calcium-phosphate biomaterials (SHB) is used with and without the addition of Platelet Rich Fibrin (aPRF) in the Piezotome-enhanced subperiosteal tunnel-technique (PeSPTT). Material and Methods. 82 patients with horizontal atrophy of anterior maxillary crest were treated with PeSPTT and randomly assigned biphasic (60% HA/40% bTCP) or monophasic (100% bTCP) SHB without or with addition of aPRF. 109 implants were inserted into the augmented sites after 8.3 months and the insertion-torque-value (ITV) measured as clinical expression of the (bio)mechanical stability of the augmented bone and compared to ITVs of a prior study in sinus lifting. Results. Significant better results of (bio)mechanical stability almost by two-fold, expressed by higher ITVs compared to native bone, were achieved with the used biomaterials and more constant results with the addition of aPRF. Conclusion. The use of SHB alone or combined with aPRF seems to be favourable to achieve a superior (bio)mechanical stable restored alveolar bone. PMID:25954758

Effects of Taping and Orthoses on Foot Biomechanics in Adults with Flat-Arched Feet.

PubMed

Bishop, Christopher; Arnold, John B; May, Thomas

2016-04-01

There is a paucity of evidence on the biomechanical effects of foot taping and foot orthoses in realistic conditions. This study aimed to determine the immediate effect and relationships between changes in multisegment foot biomechanics with foot taping and customized foot orthoses in adults with flat-arched feet. Multisegment foot biomechanics were measured in 18 adults with flat-arched feet (age 25.1 ± 2.8 yr; height 1.73 ± .13 m, body mass 70.3 ± 15.7 kg) during walking in four conditions in random order: neutral athletic shoe, neutral shoe with tape (low-Dye method and modified method) and neutral shoe with customized foot orthoses. In-shoe foot biomechanics were compared between conditions using a purpose developed foot model with three-dimensional kinematic analysis and inverse dynamics. Foot orthoses significantly delayed peak eversion compared to the neutral shoe (44% stance vs 39%, P = 0.002). Deformation across the midfoot and medial longitudinal arch was reduced with both the low-Dye taping (2.4°, P < 0.001) and modified taping technique (5.5°, P < 0.001). All interventions increased peak dorsiflexion of the first metatarsophalangeal joint (1.4°-3.2°, P < 0.001-0.023). Biomechanical responses to taping significantly predicted corresponding changes to foot orthoses (R2 = 0.08-0.52, P = 0.006 to <0.001). Foot orthoses more effectively altered timing of hindfoot motion whereas taping was superior in supporting the midfoot and medial longitudinal arch. The biomechanical response to taping was significantly related to the subsequent change observed with the use of foot orthoses.

Twenty-year trends of authorship and sampling in applied biomechanics research.

PubMed

Knudson, Duane

2012-02-01

This study documented the trends in authorship and sampling in applied biomechanics research published in the Journal of Applied Biomechanics and ISBS Proceedings. Original research articles of the 1989, 1994, 1999, 2004, and 2009 volumes of these serials were reviewed, excluding reviews, modeling papers, technical notes, and editorials. Compared to 1989 volumes, the mean number of authors per paper significantly increased (35 and 100%, respectively) in the 2009 volumes, along with increased rates of hyperauthorship, and a decline in rates of single authorship. Sample sizes varied widely across papers and did not appear to change since 1989.

Biomechanical analysis of two fixation methods for proximal chevron osteotomy of the first metatarsal.

PubMed

Schuh, Reinhard; Hofstaetter, Jochen Gerhard; Benca, Emir; Willegger, Madeleine; von Skrbensky, Gobert; Zandieh, Shahin; Wanivenhaus, Axel; Holinka, Johannes; Windhager, Reinhard

2014-05-01

The proximal chevron osteotomy provides high correctional power. However, relatively high rates of dorsiflexion malunion of up to 17 % are reported for this procedure. This leads to insufficient weight bearing of the first ray and therefore to metatarsalgia. Recent biomechanical and clinical studies pointed out the importance of rigid fixation of proximal metatarsal osteotomies. Therefore, the aim of the present study was to compare biomechanical properties of fixation of proximal chevron osteotomies with variable locking plate and cancellous screw respectively. Ten matched pairs of human fresh frozen cadaveric first metatarsals underwent proximal chevron osteotomy with either variable locking plate or cancellous screw fixation after obtaining bone mineral density. Biomechanical testing included repetitive plantar to dorsal loading from 0 to 31 N with the 858 Mini Bionix(®) (MTS(®) Systems Corporation, Eden Prairie, MN, USA). Dorsal angulation of the distal fragment was recorded. The variable locking plate construct reveals statistically superior results in terms of bending stiffness and dorsal angulation compared to the cancellous screw construct. There was a statistically significant correlation between bone mineral density and maximum tolerated load until construct failure occurred for the screw construct (r = 0.640, p = 0.406). The results of the present study indicate that variable locking plate fixation shows superior biomechanical results to cancellous screw fixation for proximal chevron osteotomy. Additionally, screw construct failure was related to levels of low bone mineral density. Based on the results of the present study we recommend variable locking plate fixation for proximal chevron osteotomy, especially in osteoporotic bone.

Knee Biomechanics During Jogging After Arthroscopic Partial Meniscectomy: A Longitudinal Study.

PubMed

Hall, Michelle; Wrigley, Tim V; Metcalf, Ben R; Hinman, Rana S; Cicuttini, Flavia M; Dempsey, Alasdair R; Lloyd, David G; Bennell, Kim L

2017-07-01

Altered knee joint biomechanics is thought to play a role in the pathogenesis of knee osteoarthritis and has been reported in patients after arthroscopic partial meniscectomy (APM) while performing various activities. Longitudinally, understanding knee joint biomechanics during jogging may assist future studies to assess the implications of jogging on knee joint health in this population. To investigate knee joint biomechanics during jogging in patients 3 months after APM and a healthy control group at baseline and 2 years later at follow-up. Controlled laboratory study. Seventy-eight patients who underwent medial APM and 38 healthy controls underwent a 3-dimensional motion analysis during barefoot overground jogging at baseline. Sixty-four patients who underwent APM and 23 controls returned at follow-up. External peak moments (flexion and adduction) and the peak knee flexion angle during stance were evaluated for the APM leg, non-APM leg (nonoperated leg), and control leg. At baseline, the peak knee flexion angle was 1.4° lower in the APM leg compared with the non-APM leg ( P = .03). No differences were found between the moments in the APM leg compared with the control leg (all P > .05). However, the normalized peak knee adduction moment was 35% higher in the non-APM leg compared with the control leg ( P = .008). In the non-APM leg, the normalized peak knee adduction and flexion moments were higher compared with the APM leg by 16% and 10%, respectively, at baseline ( P ≤ .004). Despite the increase in the peak knee flexion moment in the APM leg compared with the non-APM leg ( P < .001), there were no differences in the peak knee flexion moment or any other parameter assessed at 2-year follow-up between the legs ( P > .05). Comparing the APM leg and control leg, no differences in knee joint biomechanics during jogging for the variables assessed were observed. Higher knee moments in the non-APM leg may have clinical implications for the noninvolved leg. Kinematic differences were small (~1.4°) and therefore of questionable clinical relevance. These results may facilitate future clinical research regarding the implications of jogging on knee joint health in middle-aged, overweight patients after APM.

A pilot study of biomechanical assessment before and after an integrative training program for adolescents with juvenile fibromyalgia.

PubMed

Tran, Susan T; Thomas, Staci; DiCesare, Christopher; Pfeiffer, Megan; Sil, Soumitri; Ting, Tracy V; Williams, Sara E; Myer, Gregory D; Kashikar-Zuck, Susmita

2016-07-22

Adolescents with juvenile fibromyalgia (JFM) tend to be very sedentary and avoid participation in physical activity. A prior study suggested that JFM patients show altered biomechanics compared to healthy adolescents which may make them more prone to pain/injury during exercise. A new intervention combining well established cognitive behavioral therapy (CBT) techniques with specialized neuromuscular exercise -Fibromyalgia Integrative Training for Teens (FIT Teens) was developed and shown to be promising in improving functioning in adolescents with JFM. In contrast to traditional exercise programs such as aerobic or resistance training, neuromuscular training is a tailored approach which targets gait, posture, balance and movement mechanics which form the foundation for safe exercise participation with reduced risk for injury or pain (and hence more tolerable by JFM patients). The aim of this pilot feasibility study was to establish whether objective biomechanical assessment including sophisticated 3-D motion analysis would be useful in measuring improvements in strength, balance, gait, and functional performance after participation in the 8-week FIT Teens program. Eleven female participants with JFM (ages 12-18 years) completed pre- and post-treatment assessments of biomechanics, including walking gait analysis, lower extremity strength assessment, functional performance, and dynamic postural stability. Descriptive data indicated that mechanics of walking gait and functional performance appeared to improve after treatment. Hip abduction strength and dynamic postural control also demonstrated improvements bilaterally. Overall, the results of this pilot study offer initial evidence for the utility of biomechanical assessment to objectively demonstrate observable changes in biomechanical performance after an integrated training intervention for youth with JFM. If replicated in larger controlled studies, findings would suggest that through the FIT Teens intervention, adolescents with JFM can progress towards normalized strength and biomechanics, which may enhance their ability to engage in physical exercise.

Development of a Dynamic Biomechanical Model for Load Carriage: Phase 1 Part A: Equipment Upgrades to Accommodate Dynamic Biomechanical Modeling

DTIC Science & Technology

2005-08-01

of a magnetic tracking device to kinesiology studies. J. Biomech. 21(7), 613-620, 1988. Bryant, J.T. Stevenson, J.M., Pelot, R.P., Reid, S.A...kangaroos (Macropus rufus). Comparative Biochemistry and Physiology, Part B 120:41-49, 1998. Kram, R. Are efficiency and the cost of generating force both

Double row equivalent for rotator cuff repair: A biomechanical analysis of a new technique.

PubMed

Robinson, Sean; Krigbaum, Henry; Kramer, Jon; Purviance, Connor; Parrish, Robin; Donahue, Joseph

2018-06-01

There are numerous configurations of double row fixation for rotator cuff tears however, there remains to be a consensus on the best method. In this study, we evaluated three different double-row configurations, including a new method. Our primary question is whether the new anchor and technique compares in biomechanical strength to standard double row techniques. Eighteen prepared fresh frozen bovine infraspinatus tendons were randomized to one of three groups including the New Double Row Equivalent, Arthrex Speedbridge and a transosseous equivalent using standard Stabilynx anchors. Biomechanical testing was performed on humeri sawbones and ultimate load, strain, yield strength, contact area, contact pressure, and a survival plots were evaluated. The new double row equivalent method demonstrated increased survival as well as ultimate strength at 415N compared to the remainder testing groups as well as equivalent contact area and pressure to standard double row techniques. This new anchor system and technique demonstrated higher survival rates and loads to failure than standard double row techniques. This data provides us with a new method of rotator cuff fixation which should be further evaluated in the clinical setting. Basic science biomechanical study.

Biomechanical and organisational stressors and associations with employment withdrawal among pregnant workers: evidence and implications.

PubMed

Guendelman, Sylvia; Gemmill, Alison; MacDonald, Leslie A

2016-12-01

The distribution of exposure to biomechanical and organisational job stressors (BOJS) and associations with employment withdrawal (antenatal leave, unemployment) was examined in a case-control study of 1114 pregnant workers in California. We performed descriptive and multivariate logistic and multinomial regression analyses. At pregnancy onset, 57% were exposed to one or more biomechanical stressors, including frequent bending, heavy lifting and prolonged standing. One-third were simultaneously exposed to BOJS. Exposure to biomechanical stressors declined as pregnancy progressed and cessation often (41%) coincided with employment withdrawal (antenatal leave and unemployment). In multivariate modelling, whether we adjusted for or considered organisational stressors as coincident exposures, results showed that pregnant workers exposed to biomechanical stressors had increased employment withdrawal compared to the unexposed. Work schedule accommodations moderate this association. Paid antenatal leave, available to few US women, was an important strategy for mitigating exposure to BOJS. Implications for science and policy are discussed. Practitioner Summary: This case-control study showed that exposure to biomechanical stressors decline throughout pregnancy. Antenatal leave was an important strategy used for mitigating exposure among sampled California women with access to paid benefits. Employment withdrawal among workers exposed to BJOS may be reduced by proactive administrative and engineering efforts applied early in pregnancy.

Application of a model to analyze shoulder biomechanics in adult patients with spinal cord injury when walking with crutches in two different gait patterns.

PubMed

Perez-Rizo, Enrique; Trincado-Alonso, Fernando; Pérez-Nombela, Soraya; Del Ama-Espinosa, Antonio; Jiménez-Díaz, Fernando; Lozano-Berrio, Vicente; Gil-Agudo, Angel

2017-01-01

Specific biomechanical models have been developed to study gait using crutches. Clinical application of these models is needed in adult spinal cord injury (SCI) population walking with different patterns of gait with crutches to prevent overuse shoulder injuries. To apply a biomechanical model in a clinical environment to analyze shoulder in adult SCI patients walking with two different patterns of gait with crutches: two point reciprocal gait (RG) and swing-through gait (SG). Load cells were fixed to the distal ends and forearm cuffs of a pair of crutches. An active markers system was used for kinematics. Five cycles for each gait pattern were analyzed applying a biomechanical model of the upper limbs. Fifteen subjects with SCI were analyzed. The flexo-extension range of motion was significantly greater when using SG (p < 0.01). Similarly, the superior, posterior and medial forces were significantly stronger for SG in all 3 directions. Flexion, adduction and internal rotation torques were also greater in SG (p < 0.01). A biomechanical model was successfully applied to study shoulder biomechanics in adult patients with SCI walking with crutches in two different gait patterns. Greater loads exerted on the shoulder walking with SG were confirmed compared to RG.

An Anatomic and Biomechanical Comparison of Bankart Repair Configurations.

PubMed

Judson, Christopher H; Voss, Andreas; Obopilwe, Elifho; Dyrna, Felix; Arciero, Robert A; Shea, Kevin P

2017-11-01

Suture anchor repair for anterior shoulder instability can be performed using a number of different repair techniques, but none has been proven superior in terms of anatomic and biomechanical properties. Purpose/Hypothesis: The purpose was to compare the anatomic footprint coverage and biomechanical characteristics of 4 different Bankart repair techniques: (1) single row with simple sutures, (2) single row with horizontal mattress sutures, (3) double row with sutures, and (4) double row with labral tape. The hypotheses were as follows: (1) double-row techniques would improve the footprint coverage and biomechanical properties compared with single-row techniques, (2) horizontal mattress sutures would increase the footprint coverage compared with simple sutures, and (3) repair techniques with labral tape and sutures would not show different biomechanical properties. Controlled laboratory study. Twenty-four fresh-frozen cadaveric specimens were dissected. The native labrum was removed and the footprint marked and measured. Repair for each of the 4 groups was performed, and the uncovered footprint was measured using a 3-dimensional digitizer. The strength of the repair sites was assessed using a servohydraulic testing machine and a digital video system to record load to failure, cyclic displacement, and stiffness. The double-row repair techniques with sutures and labral tape covered 73.4% and 77.0% of the footprint, respectively. These percentages were significantly higher than the footprint coverage achieved by single-row repair techniques using simple sutures (38.1%) and horizontal mattress sutures (32.8%) ( P < .001). The footprint coverage of the simple suture and horizontal mattress suture groups was not significantly different ( P = .44). There were no significant differences in load to failure, cyclic displacement, or stiffness between the single-row and double-row groups or between the simple suture and horizontal mattress suture techniques. Likewise, there was no difference in the biomechanical properties of the double-row repair techniques with sutures versus labral tape. Double-row repair techniques provided better coverage of the native footprint of the labrum but did not provide superior biomechanical properties compared with single-row repair techniques. There was no difference in footprint coverage or biomechanical strength between the simple suture and horizontal mattress suture repair techniques. Although the double-row repair techniques had no difference in initial strength, they may improve healing in high-risk patients by improving the footprint coverage.

Trunk, pelvis and hip biomechanics in individuals with femoroacetabular impingement syndrome: Strategies for step ascent.

PubMed

Diamond, Laura E; Bennell, Kim L; Wrigley, Tim V; Hinman, Rana S; Hall, Michelle; O'Donnell, John; Hodges, Paul W

2018-03-01

Femoroacetabular impingment (FAI) syndrome is common among young active adults and a proposed risk factor for the future development of hip osteoarthritis. Pain is dominant and drives clinical decision-making. Evidence for altered hip joint function in this patient population is inconsistent, making the identification of treatment targets challenging. A broader assessment, considering adjacent body segments (i.e. pelvis, trunk) and individual movement strategies, may better inform treatment programs. This exploratory study aimed to compare trunk, pelvis, and hip biomechanics during step ascent between individuals with and without FAI syndrome. Fifteen participants diagnosed with symptomatic cam-type or combined (cam plus pincer) FAI who were scheduled for arthroscopic surgery, and 11 age-, and sex-comparable pain- and disease-free individuals, underwent three-dimensional motion analysis during a step ascent task. Trunk, pelvis and hip biomechanics were compared between groups. Participants with FAI syndrome exhibited altered ipsilateral trunk lean and pelvic rise towards the symptomatic side during single-leg support compared to controls. Alterations were not uniformly adopted across all individuals with FAI syndrome; those who exhibited more pronounced alterations to frontal plane pelvis control tended to report pain during the task. There were minimal between-group differences for hip biomechanics. Exploratory data suggest biomechanics at the trunk and pelvis during step ascent differ between individuals with and without FAI syndrome. Those with FAI syndrome implement a range of proximal strategies for task completion, some of which may have relevance for rehabilitation. Longitudinal investigations of larger cohorts are required to evaluate hypothesized clinical and structural consequences. Copyright © 2018 Elsevier B.V. All rights reserved.

Changes in Drop-Jump Landing Biomechanics During Prolonged Intermittent Exercise

PubMed Central

Schmitz, Randy J.; Cone, John C.; Tritsch, Amanda J.; Pye, Michele L.; Montgomery, Melissa M.; Henson, Robert A.; Shultz, Sandra J.

2014-01-01

Background: As injury rates rise in the later stages of sporting activities, a better understanding of lower extremity biomechanics in the later phases of gamelike situations may improve training and injury prevention programs. Hypothesis: Lower extremity biomechanics of a drop-jump task (extracted from a principal components analysis) would reveal factors associated with risk of anterior cruciate ligament injury during a 90-minute individualized intermittent exercise protocol (IEP) and for 1 hour following the IEP. Study Design: Controlled laboratory study. Level of Evidence: Level 4. Methods: Fifty-nine athletes (29 women, 30 men) completed 3 sessions. The first session assessed fitness for an IEP designed to simulate the demands of a soccer match. An experimental session assessed drop-jump biomechanics, after a dynamic warm-up, every 15 minutes during the 90-minute IEP, and for 1 hour following the IEP. A control session with no exercise assessed drop-jump performance at the same intervals. Results: Two biomechanical factors early in the first half (hip flexion at initial contact and hip loading; ankle loading and knee shear force) decreased at the end of the IEP and into the 60-minute recovery period, while a third factor (knee loading) decreased only during the recovery period (P ≤ 0.05). Conclusion: The individualized sport-specific IEP may have more subtle effects on landing biomechanics when compared with short-term, exhaustive fatigue protocols. Clinical Relevance: Potentially injurious landing biomechanics may not occur until the later stages of soccer activity. PMID:24587862

THE INFLUENCE OF SEX AND MATURATION ON LANDING BIOMECHANICS: IMPLICATIONS FOR ACL INJURY

PubMed Central

Sigward, S. M.; Pollard, C. D.; Powers, C. M.

2010-01-01

During landing and cutting, females exhibit greater frontal plane moments at the knee (internal knee adductor moments or external knee abduction moments) and favor use of the knee extensors over the hip extensors to attenuate impact forces when compared to males. However, it is not known when this biomechanical profile emerges. The purpose of this study was to compare landing biomechanics between sexes across maturation levels. One hundred and nineteen male and female soccer players (9–22 years) participated. Subjects were grouped based on maturational development. Lower extremity kinematics and kinetics were obtained during a drop-land task. Dependent variables included the average internal knee adductor moment and sagittal plane knee/hip moment and energy absorption ratios during the deceleration phase of landing. When averaged across maturation levels, females demonstrated greater internal knee adductor moments (0.06±0.03 vs. 0.01±0.02 Nm/kg*m; P<0.005), knee/hip extensor moment ratios (2.0±0.1 vs. 1.4±0.1 Nm/kg*m; P<0.001), and knee/hip energy absorption ratios (2.9±0.1 vs. 1.96±0.1 Nm/kg*m; P<0.001) compared to males. Higher knee adductor moments combined with disproportionate use of knee extensors relative to hip extensors observed in females reflects a biomechanical pattern that increases ACL loading. This biomechanical strategy already was established in pre-pubertal female athletes. PMID:21210853

The Biomechanical Support of Eight Selected Sports Bras for Small, Medium and Large Breasted Women while Jogging.

ERIC Educational Resources Information Center

Lorentzen, Deana; Lawson, LaJean

This study compared the biomechanical support offered by eight presently marketed sports bras for small-, medium-, and large-breasted women while jogging. Fifty-nine subjects were filmed while jogging on a treadmill in each of the bras and in the nude condition. The vertical displacement of the breast relative to the body during one average…

Technique for Chestband Contour Shape-Mapping in Lateral Impact

PubMed Central

Hallman, Jason J; Yoganandan, Narayan; Pintar, Frank A

2011-01-01

The chestband transducer permits noninvasive measurement of transverse plane biomechanical response during blunt thorax impact. Although experiments may reveal complex two-dimensional (2D) deformation response to boundary conditions, biomechanical studies have heretofore employed only uniaxial chestband contour quantifying measurements. The present study described and evaluated an algorithm by which source subject-specific contour data may be systematically mapped to a target generalized anthropometry for computational studies of biomechanical response or anthropomorphic test dummy development. Algorithm performance was evaluated using chestband contour datasets from two rigid lateral impact boundary conditions: Flat wall and anterior-oblique wall. Comparing source and target anthropometry contours, peak deflections and deformation-time traces deviated by less than 4%. These results suggest that the algorithm is appropriate for 2D deformation response to lateral impact boundary conditions. PMID:21676399

Smoothing spline analysis of variance models: A new tool for the analysis of cyclic biomechanical data.

PubMed

Helwig, Nathaniel E; Shorter, K Alex; Ma, Ping; Hsiao-Wecksler, Elizabeth T

2016-10-03

Cyclic biomechanical data are commonplace in orthopedic, rehabilitation, and sports research, where the goal is to understand and compare biomechanical differences between experimental conditions and/or subject populations. A common approach to analyzing cyclic biomechanical data involves averaging the biomechanical signals across cycle replications, and then comparing mean differences at specific points of the cycle. This pointwise analysis approach ignores the functional nature of the data, which can hinder one׳s ability to find subtle differences between experimental conditions and/or subject populations. To overcome this limitation, we propose using mixed-effects smoothing spline analysis of variance (SSANOVA) to analyze differences in cyclic biomechanical data. The SSANOVA framework makes it possible to decompose the estimated function into the portion that is common across groups (i.e., the average cycle, AC) and the portion that differs across groups (i.e., the contrast cycle, CC). By partitioning the signal in such a manner, we can obtain estimates of the CC differences (CCDs), which are the functions directly describing group differences in the cyclic biomechanical data. Using both simulated and experimental data, we illustrate the benefits of using SSANOVA models to analyze differences in noisy biomechanical (gait) signals collected from multiple locations (joints) of subjects participating in different experimental conditions. Using Bayesian confidence intervals, the SSANOVA results can be used in clinical and research settings to reliably quantify biomechanical differences between experimental conditions and/or subject populations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparison of landing biomechanics between male and female dancers and athletes, part 1: Influence of sex on risk of anterior cruciate ligament injury.

PubMed

Orishimo, Karl F; Liederbach, Marijeanne; Kremenic, Ian J; Hagins, Marshall; Pappas, Evangelos

2014-05-01

The incidence of anterior cruciate ligament (ACL) injuries among dancers is much lower than among team sport athletes, and no clear disparity between sexes has been reported in the dance population. Although numerous studies have observed differences in landing biomechanics of the lower extremity between male and female team sport athletes, there is currently little research examining the landing biomechanics of male and female dancers and none comparing athletes to dancers. Comparing the landing biomechanics within these populations may help explain the lower overall ACL injury rates and lack of sex disparity. The purpose was to compare the effects of sex and group (dancer vs team sport athlete) on single-legged drop-landing biomechanics. The primary hypothesis was that female dancers would perform a drop-landing task without demonstrating typical sex-related risk factors associated with ACL injuries. A secondary hypothesis was that female team sport athletes would display typical ACL risk factors during the same task. Controlled laboratory study. Kinematics and kinetics were recorded as 40 elite modern and ballet dancers (20 men and 20 women) and 40 team sport athletes (20 men and 20 women) performed single-legged drop landings from a 30-cm platform. Joint kinematics and kinetics were compared between groups and sexes with a group-by-sex multivariate analysis of variance (MANOVA) followed by pairwise t tests. Dancers of both sexes and male team sport athletes landed similarly in terms of frontal-plane knee alignment, whereas female team sport athletes landed with a significantly greater peak knee valgus (P = .007). Female dancers were found to have a lower hip adduction torque than those of the other 3 groups (P = .003). Dancers (male and female) exhibited a lower trunk side flexion (P = .002) and lower trunk forward flexion (P = .032) compared with team sport athletes. In executing a 30-cm drop landing, female team sport athletes displayed a greater knee valgus than did the other 3 groups. Dancers exhibited better trunk stability than did athletes. These biomechanical findings may provide insight into the cause of the epidemiological differences in ACL injuries between dancers and athletes and the lack of a sex disparity within dancers.

Poor relation between biomechanical and clinical studies for the proximal femoral locking compression plate

PubMed Central

Viberg, Bjarke; Rasmussen, Katrine M V; Overgaard, Søren; Rogmark, Cecilia

2017-01-01

Background and purpose The proximal femur locking compression plate (PF-LCP) is a new concept in the treatment of hip fractures. When releasing new implants onto the market, biomechanical studies are conducted to evaluate performance of the implant. We investigated the relation between biomechanical and clinical studies on PF-LCP. Methods A systematic literature search of relevant biomechanical and clinical studies was conducted in PubMed on December 1, 2015. 7 biomechanical studies and 15 clinical studies were included. Results Even though the biomechanical studies showed equivalent or higher failure loads for femoral neck fracture, the clinical results were far worse, with a 37% complication rate. There were no biomechanical studies on pertrochanteric fractures. Biomechanical studies on subtrochanteric fractures showed that PF-LCP had a lower failure load than with proximal femoral nail, but higher than with angled blade plate. 4 clinical studies had complication rates less than 8% and 9 studies had complication rates between 15% and 53%. Interpretation There was no clear relation between biomechanical and clinical studies. Biomechanical studies are generally inherently different from clinical studies, as they examine the best possible theoretical use of the implant without considering the long-term outcome in a clinical setting. Properly designed clinical studies are mandatory when introducing new implants, and they cannot be replaced by biomechanical studies. PMID:28287002

Single-row modified mason-allen versus double-row arthroscopic rotator cuff repair: a biomechanical and surface area comparison.

PubMed

Nelson, Cory O; Sileo, Michael J; Grossman, Mark G; Serra-Hsu, Frederick

2008-08-01

The purpose of this study was to compare the time-zero biomechanical strength and the surface area of repair between a single-row modified Mason-Allen rotator cuff repair and a double-row arthroscopic repair. Six matched pairs of sheep infraspinatus tendons were repaired by both techniques. Pressure-sensitive film was used to measure the surface area of repair for each configuration. Specimens were biomechanically tested with cyclic loading from 20 N to 30 N for 20 cycles and were loaded to failure at a rate of 1 mm/s. Failure was defined at 5 mm of gap formation. Double-row suture anchor fixation restored a mean surface area of 258.23 +/- 69.7 mm(2) versus 148.08 +/- 75.5 mm(2) for single-row fixation, a 74% increase (P = .025). Both repairs had statistically similar time-zero biomechanics. There was no statistical difference in peak-to-peak displacement or elongation during cyclic loading. Single-row fixation showed a higher mean load to failure (110.26 +/- 26.4 N) than double-row fixation (108.93 +/- 21.8 N). This was not statistically significant (P = .932). All specimens failed at the suture-tendon interface. Double-row suture anchor fixation restores a greater percentage of the anatomic footprint when compared with a single-row Mason-Allen technique. The time-zero biomechanical strength was not significantly different between the 2 study groups. This study suggests that the 2 factors are independent of each other. Surface area and biomechanical strength of fixation are 2 independent factors in the outcome of rotator cuff repair. Maximizing both factors may increase the likelihood of complete tendon-bone healing and ultimately improve clinical outcomes. For smaller tears, a single-row modified Mason-Allen suture technique may provide sufficient strength, but for large amenable tears, a double row can provide both strength and increased surface area for healing.

Utilization of ACL Injury Biomechanical and Neuromuscular Risk Profile Analysis to Determine the Effectiveness of Neuromuscular Training.

PubMed

Hewett, Timothy E; Ford, Kevin R; Xu, Yingying Y; Khoury, Jane; Myer, Gregory D

2016-12-01

The widespread use of anterior cruciate ligament (ACL) injury prevention interventions has not been effective in reducing the injury incidence among female athletes who participate in high-risk sports. The purpose of this study was to determine if biomechanical and neuromuscular factors that contribute to the knee abduction moment (KAM), a predictor of future ACL injuries, could be used to characterize athletes by a distinct factor. Specifically, we hypothesized that a priori selected biomechanical and neuromuscular factors would characterize participants into distinct at-risk profiles. Controlled laboratory study. A total of 624 female athletes who participated in jumping, cutting, and pivoting sports underwent testing before their competitive season. During testing, athletes performed drop-jump tasks from which biomechanical measures were captured. Using data from these tasks, latent profile analysis (LPA) was conducted to identify distinct profiles based on preintervention biomechanical and neuromuscular measures. As a validation, we examined whether the profile membership was a significant predictor of the KAM. LPA using 6 preintervention biomechanical measures selected a priori resulted in 3 distinct profiles, including a low (profile 1), moderate (profile 2), and high (profile 3) risk for ACL injuries. Athletes with profiles 2 and 3 had a significantly higher KAM compared with those with profile 1 (P < .05). This is the first study to use LPA of biomechanical landing data to create ACL injury risk profiles. Three distinct risk groups were identified based on differences in the peak KAM. These findings demonstrate the existence of discernable groups of athletes that may benefit from injury prevention interventions. ClinicalTrials.gov NCT identifier: NCT01034527. © 2016 The Author(s).

Biomechanical comparison between bicortical pin and monocortical screw/polymethylmethacrylate constructs in the cadaveric canine cervical vertebral column.

PubMed

Hettlich, Bianca F; Allen, Matthew J; Pascetta, Daniel; Fosgate, Geoffrey T; Litsky, Alan S

2013-08-01

To compare biomechanical stiffness of cadaveric canine cervical spine constructs stabilized with bicortical stainless steel pins and polymethylmethacrylate (PMMA), monocortical stainless steel screws with PMMA, or monocortical titanium screws with PMMA. Biomechanical cadaver study. Eighteen canine cervical vertebral columns (C2-C7) were collected from skeletally mature dogs (weighing 22-32 kg). Specimens were radiographed and examined by dual energy X-ray absorptiometry. Stiffness of the unaltered C4-C5 intervertebral motion unit was measured in extension, flexion and lateral bending using non-destructive 4-point bend testing. Specimens were then stabilized by (1) bicortical stainless steel pins/PMMA, (2) monocortical stainless steel screws/PMMA, or (3) monocortical titanium screws/PMMA. Mechanical testing was repeated and stiffness data from unaltered specimens and the 3 treatment groups were compared. All 3 surgical methods significantly increased stiffness of the C4-C5 motion unit compared with the unaltered specimen (P < .001 for all treatments), but stiffness was not significantly different among the 3 fixation groups (P = .578). In this model, monocortical screw fixation (with stainless steel or titanium screws) was biomechanically equivalent to bicortical fixation. © Copyright 2013 by The American College of Veterinary Surgeons.

Neck muscle biomechanics and neural control.

PubMed

Fice, Jason Bradley; Siegmund, Gunter P; Blouin, Jean-Sebastien

2018-04-18

The mechanics, morphometry, and geometry of our joints, segments and muscles are fundamental biomechanical properties intrinsic to human neural control. The goal of our study was to investigate if the biomechanical actions of individual neck muscles predicts their neural control. Specifically, we compared the moment direction & variability produced by electrical stimulation of a neck muscle (biomechanics) to their preferred activation direction & variability (neural control). Subjects sat upright with their head fixed to a 6-axis load cell and their torso restrained. Indwelling wire electrodes were placed into the sternocleidomastoid (SCM), splenius capitis (SPL), and semispinalis capitis (SSC) muscles. The electrically stimulated direction was defined as the moment direction produced when a current (2-19mA) was passed through each muscle's electrodes. Preferred activation direction was defined as the vector sum of the spatial tuning curve built from RMS EMG when subjects produced isometric moments at 7.5% and 15% of their maximum voluntary contraction (MVC) in 26 3D directions. The spatial tuning curves at 15% MVC were well-defined (unimodal, p<0.05) and their preferred directions were 23, 39, & 21{degree sign} different from their electrically stimulated directions for the SCM, SPL, and SSC respectively (p<0.05). Intra-subject variability was smaller in electrically stimulated moment directions when compared to voluntary preferred directions, and intra-subject variability decreased with increased activation levels. Our findings show that the neural control of neck muscles is not based solely on optimizing individual muscle biomechanics but, as activation increases, biomechanical constraints in part dictate the activation of synergistic neck muscles.

Associations between iliotibial band injury status and running biomechanics in women.

PubMed

Foch, Eric; Reinbolt, Jeffrey A; Zhang, Songning; Fitzhugh, Eugene C; Milner, Clare E

2015-02-01

Iliotibial band syndrome (ITBS) is a common overuse knee injury that is twice as likely to afflict women compared to men. Lower extremity and trunk biomechanics during running, as well as hip abductor strength and iliotibial band flexibility, are factors believed to be associated with ITBS. The purpose of this cross-sectional study was to determine if differences in lower extremity and trunk biomechanics during running exist among runners with current ITBS, previous ITBS, and controls. Additionally, we sought to determine if isometric hip abductor strength and iliotibial band flexibility were different among groups. Twenty-seven female runners participated in the study. Participants were divided into three equal groups: current ITBS, previous ITBS, and controls. Overground running trials, isometric hip abductor strength, and iliotibial band flexibility were recorded for all participants. Discrete joint and segment biomechanics, as well as hip strength and flexibility measures were analyzed using a one-way analysis of variance. Runners with current ITBS exhibited 1.8 (1.5)° greater trunk ipsilateral flexion and 7 (6)° less iliotibial band flexibility compared to runners with previous ITBS and controls. Runners with previous ITBS exhibited 2.2 (2.9) ° less hip adduction compared to runners with current ITBS and controls. Hip abductor strength 3.3 (2.6) %BM×h was less in runners with previous ITBS but not current ITBS compared to controls. Runners with current ITBS may lean their trunk more towards the stance limb which may be associated with decreased iliotibial band flexibility. Copyright © 2015 Elsevier B.V. All rights reserved.

Magnetic Resonance Imaging-Based Assessment of Carotid Atheroma: a Comparative Study of Patients with and without Coronary Artery Disease.

PubMed

Usman, Ammara; Sadat, Umar; Teng, Zhongzhao; Graves, Martin J; Boyle, Jonathan R; Varty, Kevin; Hayes, Paul D; Gillard, Jonathan H

2017-02-01

Functional magnetic resonance (MR) imaging of atheroma using contrast media enables assessment of the systemic severity of atherosclerosis in different arterial beds. Whether black-blood imaging has similar ability remains widely unexplored. In this study, we evaluate whether black-blood imaging can differentiate carotid plaques of patients with and without coronary artery disease (CAD) in terms of morphological and biomechanical features of plaque vulnerability, thereby allowing assessment of the systemic severity nature of atherosclerosis in different arterial beds. Forty-one patients with CAD and 59 patients without CAD underwent carotid black-blood MR imaging. Plaque components were segmented to identify large lipid core (LC), ruptured fibrous cap (FC), and plaque hemorrhage (PH). These segmented contours of plaque components were used to quantify maximum structural biomechanical stress. Patients with CAD and without CAD had comparable demographics and comorbidities. Both groups had comparable prevalence of morphological features of plaque vulnerability (FC rupture, 44% versus 41%, P = .90; PH, 58% versus 47%, P = .78; large LC, 32% versus 47%, P = .17), respectively. The maximum biomechanical stress was not significantly different for both groups (241versus 278 kPa, P = .14) respectively. Black-blood imaging does not appear to have the ability to differentiate between the morphological and biomechanical features of plaque vulnerability when comparing patients with and without symptomatic atherosclerotic disease in a distant arterial territory such as coronary artery. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Effect of total-contact orthosis on medial longitudinal arch and lower extremities in flexible flatfoot subjects during walking.

PubMed

Prachgosin, Tulaya; Leelasamran, Wipawan; Smithmaitrie, Pruittikorn; Chatpun, Surapong

2017-12-01

Total-contact orthosis (TCO) is one kind of foot orthosis (FO) that is used to adjust biomechanics in flexible flatfoot. To determine the effects of a TCO on the MLA moment, MLA deformation angle and lower limb biomechanics. Cross-sectional study. Seven-flatfoot and thirteen-normal foot subjects were recruited by footprint and radiographs. The biomechanics of subjects with normal foot (NF), flatfoot with shoe only (FWOT) and flatfoot with TCO (FWT) were collected in a 3D motion analysis laboratory and force plates. The MLA and lower limb biomechanics in each condition during specific sub-phases of stance were analyzed. The NF had larger MLA eversion moment after shod walking ( p = 0.001). The FWT condition compared with the FWOT condition had a significantly larger peak MLA upward moment ( p = 0.035) during pre-swing, larger peak knee external rotation angle ( p = 0.040) during mid stance, smaller peak knee extension moment during terminal stance ( p = 0.035) and a larger ground reaction force in the anterior-posterior direction during early stance ( p < 0.05). Our study found positive effects from the customized TCOs which included an increased TCO angle that led to a decreased peak MLA moment in the frontal plane in flexible flatfoot subjects during walking. Clinical relevance Lower limb biomechanics is different from normal in subjects with flexible flatfoot. The design of a TCO affects MLA, ankle and knee biomechanics and may be used to clinically correct biomechanical changes in flexible flatfoot.

Tibial Inlay Press-fit Fixation Versus Interference Screw in Posterior Cruciate Ligament Reconstruction.

PubMed

Ettinger, Max; Büermann, Sarah; Calliess, Tilman; Omar, Mohamed; Krettek, Christian; Hurschler, Christof; Jagodzinski, Michael; Petri, Maximilian

2013-01-01

Reconstruction of the posterior cruciate ligament (PCL) by a tibial press-fit fixation of the patellar tendon with an accessory bone plug is a promising approach because no foreign materials are required. Until today, there is no data about the biomechanical properties of such press-fit fixations. The aim of this study was to compare the biomechanical qualities of a bone plug tibial inlay technique with the commonly applied interference screw of patellar tendon PCL grafts. Twenty patellar tendons including a bone block were harvested from ten human cadavers. The grafts were implanted into twenty legs of adult German country pigs. In group P, the grafts were attached in a press-fit technique with accessory bone plug. In group S, the grafts were fixed with an interference screw. Each group consisted of 10 specimens. The constructs were biomechanically analyzed in cyclic loading between 60 and 250 N for 500 cycles recording elongation. Finally, ultimate failure load and failure mode were analyzed. Ultimate failure load was 598.6±36.3 N in group P and 653.7±39.8 N in group S (not significant, P>0.05). Elongation during cyclic loading between the 1(st) and the 20(th) cycle was 3.4±0.9 mm for group P and 3.1±1 mm for group S. Between the 20(th) and the 500(th) cycle, elongation was 4.2±2.3 mm in group P and 2.5±0.9 mm in group S (not significant, P>0.05). This is the first study investigating the biomechanical properties of tibial press-fit fixation of the patellar tendon with accessory bone plug in posterior cruciate ligament reconstruction. The implant-free tibial inlay technique shows equal biomechanical characteristics compared to an interference screw fixation. Further in vivo studies are desirable to compare the biological behavior and clinical relevance of this fixation device.

Changes in drop-jump landing biomechanics during prolonged intermittent exercise.

PubMed

Schmitz, Randy J; Cone, John C; Tritsch, Amanda J; Pye, Michele L; Montgomery, Melissa M; Henson, Robert A; Shultz, Sandra J

2014-03-01

As injury rates rise in the later stages of sporting activities, a better understanding of lower extremity biomechanics in the later phases of gamelike situations may improve training and injury prevention programs. Lower extremity biomechanics of a drop-jump task (extracted from a principal components analysis) would reveal factors associated with risk of anterior cruciate ligament injury during a 90-minute individualized intermittent exercise protocol (IEP) and for 1 hour following the IEP. Controlled laboratory study. Level 4. Fifty-nine athletes (29 women, 30 men) completed 3 sessions. The first session assessed fitness for an IEP designed to simulate the demands of a soccer match. An experimental session assessed drop-jump biomechanics, after a dynamic warm-up, every 15 minutes during the 90-minute IEP, and for 1 hour following the IEP. A control session with no exercise assessed drop-jump performance at the same intervals. Two biomechanical factors early in the first half (hip flexion at initial contact and hip loading; ankle loading and knee shear force) decreased at the end of the IEP and into the 60-minute recovery period, while a third factor (knee loading) decreased only during the recovery period (P ≤ 0.05). The individualized sport-specific IEP may have more subtle effects on landing biomechanics when compared with short-term, exhaustive fatigue protocols. Potentially injurious landing biomechanics may not occur until the later stages of soccer activity.

Micro- and nano-technologies to probe the mechano-biology of the brain.

PubMed

Tay, Andy; Schweizer, Felix E; Di Carlo, Dino

2016-05-24

Biomechanical forces have been demonstrated to influence a plethora of neuronal functions across scales including gene expression, mechano-sensitive ion channels, neurite outgrowth and folding of the cortices in the brain. However, the detailed roles biomechanical forces may play in brain development and disorders has seen limited study, partly due to a lack of effective methods to probe the mechano-biology of the brain. Current techniques to apply biomechanical forces on neurons often suffer from low throughput and poor spatiotemporal resolution. On the other hand, newly developed micro- and nano-technologies can overcome these aforementioned limitations and offer advantages such as lower cost and possibility of non-invasive control of neuronal circuits. This review compares the range of conventional, micro- and nano-technological techniques that have been developed and how they have been or can be used to understand the effect of biomechanical forces on neuronal development and homeostasis.

The influence of sex and maturation on landing biomechanics: implications for anterior cruciate ligament injury.

PubMed

Sigward, S M; Pollard, C D; Powers, C M

2012-08-01

During landing and cutting, females exhibit greater frontal plane moments at the knee (internal knee adductor moments or external knee abduction moments) and favor the use of the knee extensors over the hip extensors to attenuate impact forces when compared with males. However, it is not known when this biomechanical profile emerges. The purpose of this study was to compare landing biomechanics between sexes across maturation levels. One hundred and nineteen male and female soccer players (9-22 years) participated. Subjects were grouped based on maturational development. Lower extremity kinematics and kinetics were obtained during a drop-land task. Dependent variables included the average internal knee adductor moment and sagittal plane knee/hip moment and energy absorption ratios during the deceleration phase of landing. When averaged across maturation levels, females demonstrated greater internal knee adductor moments (0.06±0.03 vs 0.01±0.02 N m/kg m; P<0.005), knee/hip extensor moment ratios (2.0±0.1 vs 1.4±0.1 N m/kg m; P<0.001) and knee/hip energy absorption ratios (2.9±0.1 vs 1.96±0.1 N m/kg m; P<0.001) compared with males. Higher knee adductor moments combined with disproportionate use of knee extensors relative to hip extensors observed in females reflect a biomechanical pattern that increases anterior cruciate ligament loading. This biomechanical strategy already was established in pre-pubertal female athletes. © 2011 John Wiley & Sons A/S.

Dual mobility cups provide biomechanical advantages in situations at risk for dislocation: a finite element analysis.

PubMed

Terrier, Alexandre; Latypova, Adeliya; Guillemin, Maika; Parvex, Valérie; Guyen, Olivier

2017-03-01

Constrained devices, standard implants with large heads, and dual mobility systems have become popular options to manage instability after total hip arthroplasty (THA). Clinical results with these options have shown variable success rates and significant higher rates of aseptic loosening and mechanical failures with constrained implants. Literature suggests potential advantages of dual mobility, however little is known about its biomechanics. We present a comparative biomechanical study of a standard implant, a constrained implant, and a dual mobility system. A finite element analysis was developed to assess and compare these acetabular options with regard to the range of motion (ROM) to impingement, the angle of dislocation, the resistive torque, the volume of polyethylene (PE) with a stress above 80% of the elastic limit, and the interfacial cup/bone stress. Dual mobility implants provided the greatest ROM to impingement and allowed delaying subluxation and dislocation when compared to standard and constrained implants. Dual mobility also demonstrated the lowest resistive torque at subluxation while the constrained implant provided the greatest one. The lowest critical PE volume was observed with the dual mobility implant, and the highest stress at the interfaces was observed with the constrained implant. This study highlights the biomechanical advantages of dual mobility systems over constrained and standard implants, and is supported by the clinical results reported. Therefore, the use of dual mobility systems in situations at risk for instability should be advocated and constrained implants should be restricted to salvage situations.

Functional assessment of the ex vivo vocal folds through biomechanical testing: A review

PubMed Central

Dion, Gregory R.; Jeswani, Seema; Roof, Scott; Fritz, Mark; Coelho, Paulo; Sobieraj, Michael; Amin, Milan R.; Branski, Ryan C.

2016-01-01

The human vocal folds are complex structures made up of distinct layers that vary in cellular and extracellular composition. The mechanical properties of vocal fold tissue are fundamental to the study of both the acoustics and biomechanics of voice production. To date, quantitative methods have been applied to characterize the vocal fold tissue in both normal and pathologic conditions. This review describes, summarizes, and discusses the most commonly employed methods for vocal fold biomechanical testing. Force-elongation, torsional parallel plate rheometry, simple-shear parallel plate rheometry, linear skin rheometry, and indentation are the most frequently employed biomechanical tests for vocal fold tissues and each provide material properties data that can be used to compare native tissue verses diseased for treated tissue. Force-elongation testing is clinically useful, as it allows for functional unit testing, while rheometry provides physiologically relevant shear data, and nanoindentation permits micrometer scale testing across different areas of the vocal fold as well as whole organ testing. Thoughtful selection of the testing technique during experimental design to evaluate a hypothesis is important to optimizing biomechanical testing of vocal fold tissues. PMID:27127075

Anterior Cruciate Ligament Biomechanics During Robotic and Mechanical Simulations of Physiologic and Clinical Motion Tasks: A Systematic Review and Meta-Analysis

PubMed Central

Bates, Nathaniel A.; Myer, Gregory D.; Shearn, Jason T.; Hewett, Timothy E.

2014-01-01

Investigators use in vitro joint simulations to invasively study the biomechanical behaviors of the anterior cruciate ligament. The aims of these simulations are to replicate physiologic conditions, but multiple mechanisms can be used to drive in vitro motions, which may influence biomechanical outcomes. The objective of this review was to examine, summarize, and compare biomechanical evidence related to anterior cruciate ligament function from in vitro simulations of knee motion. A systematic review was conducted (2004 to 2013) in Scopus, PubMed/Medline, and SPORTDiscus to identify peer-reviewed studies that reported kinematic and kinetic outcomes from in vitro simulations of physiologic or clinical tasks at the knee. Inclusion criteria for relevant studies were articles published in English that reported on whole-ligament anterior cruciate ligament mechanics during the in vitro simulation of physiologic or clinical motions on cadaveric knees that were unaltered outside of the anterior-cruciate-ligament-intact, -deficient, and -reconstructed conditions. A meta-analysis was performed to synthesize biomechanical differences between the anterior-cruciate-ligament-intact and reconstructed conditions. 77 studies met our inclusion/exclusion criteria and were reviewed. Combined joint rotations have the greatest impact on anterior cruciate ligament loads, but the magnitude by which individual kinematic degrees of freedom contribute to ligament loading during in vitro simulations is technique-dependent. Biomechanical data collected in prospective, longitudinal studies corresponds better with robotic-manipulator simulations than mechanical-impact simulations. Robotic simulation indicated that the ability to restore intact anterior cruciate ligament mechanics with anterior cruciate ligament reconstructions was dependent on loading condition and degree of freedom examined. PMID:25547070

New approaches for cement-based prophylactic augmentation of the osteoporotic proximal femur provide enhanced reinforcement as predicted by non-linear finite element simulations.

PubMed

Varga, Peter; Inzana, Jason A; Schwiedrzik, Jakob; Zysset, Philippe K; Gueorguiev, Boyko; Blauth, Michael; Windolf, Markus

2017-05-01

High incidence and increased mortality related to secondary, contralateral proximal femoral fractures may justify invasive prophylactic augmentation that reinforces the osteoporotic proximal femur to reduce fracture risk. Bone cement-based approaches (femoroplasty) may deliver the required strengthening effect; however, the significant variation in the results of previous studies calls for a systematic analysis and optimization of this method. Our hypothesis was that efficient generalized augmentation strategies can be identified via computational optimization. This study investigated, by means of finite element analysis, the effect of cement location and volume on the biomechanical properties of fifteen proximal femora in sideways fall. Novel cement cloud locations were developed using the principles of bone remodeling and compared to the "single central" location that was previously reported to be optimal. The new augmentation strategies provided significantly greater biomechanical benefits compared to the "single central" cement location. Augmenting with approximately 12ml of cement in the newly identified location achieved increases of 11% in stiffness, 64% in yield force, 156% in yield energy and 59% in maximum force, on average, compared to the non-augmented state. The weaker bones experienced a greater biomechanical benefit from augmentation than stronger bones. The effect of cement volume on the biomechanical properties was approximately linear. Results of the "single central" model showed good agreement with previous experimental studies. These findings indicate enhanced potential of cement-based prophylactic augmentation using the newly developed cementing strategy. Future studies should determine the required level of strengthening and confirm these numerical results experimentally. Copyright © 2017 Elsevier Ltd. All rights reserved.

Higher anterior knee laxity influences the landing biomechanics displayed by pubescent girls.

PubMed

Wild, Catherine Y; Munro, Bridget J; Steele, Julie R

2017-01-01

Despite an increase in anterior knee laxity (AKL) during the adolescent growth spurt in girls, it is unknown whether landing biomechanics are affected by this change. This study investigated whether pubescent girls with higher AKL displayed differences in their lower limb strength or landing biomechanics when performing a horizontal leap movement compared to girls with lower AKL. Forty-six pubescent girls (10-13 years) were tested at the time of their peak height velocity (PHV). Passive AKL was quantified and used to classify participants into higher (HAKL; peak displacement > 4 mm) and lower (LAKL; peak displacement < 3 mm) AKL groups (n = 15/group). Three-dimensional kinematics, ground reaction forces (GRF) and muscle activation patterns were assessed during a horizontal leap landing. HAKL participants displayed significantly (P < 0.05) reduced hip abduction, increased hip abduction moments, as well as earlier hamstring muscle and later tibialis anterior activation compared to LAKL participants. Girls with HAKL displayed compensatory landing biomechanics, which are suggested to assist the functional stability of their knees during this dynamic task. Further research is warranted, however, to confirm or refute this notion.

Gender differences in gait kinematics in runners with iliotibial band syndrome.

PubMed

Phinyomark, A; Osis, S; Hettinga, B A; Leigh, R; Ferber, R

2015-12-01

Atypical running gait biomechanics are considered a primary factor in the etiology of iliotibial band syndrome (ITBS). However, a general consensus on the underpinning kinematic differences between runners with and without ITBS is yet to be reached. This lack of consensus may be due in part to three issues: gender differences in gait mechanics, the preselection of discrete biomechanical variables, and/or relatively small sample sizes. Therefore, this study was designed to address two purposes: (a) examining differences in gait kinematics for male and female runners experiencing ITBS at the time of testing and (b) assessing differences in gait kinematics between healthy gender- and age-matched runners as compared with their ITBS counterparts using waveform analysis. Ninety-six runners participated in this study: 48 ITBS and 48 healthy runners. The results show that female ITBS runners exhibited significantly greater hip external rotation compared with male ITBS and female healthy runners. On the contrary, male ITBS runners exhibited significantly greater ankle internal rotation compared with healthy males. These results suggest that care should be taken to account for gender when investigating the biomechanical etiology of ITBS. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Effects of a capacitive-resistive electric transfer therapy on physiological and biomechanical parameters in recreational runners: A randomized controlled crossover trial.

PubMed

Duñabeitia, Iratxe; Arrieta, Haritz; Torres-Unda, Jon; Gil, Javier; Santos-Concejero, Jordan; Gil, Susana M; Irazusta, Jon; Bidaurrazaga-Letona, Iraia

2018-05-26

This study compared the effects of a capacitive-resistive electric transfer therapy (Tecar) and passive rest on physiological and biomechanical parameters in recreational runners when performed shortly after an exhausting training session. Randomized controlled crossover trial. University biomechanical research laboratory. Fourteen trained male runners MAIN OUTCOME MEASURES: Physiological (running economy, oxygen uptake, respiratory exchange ratio, ventilation, heart rate, blood lactate concentration) and biomechanical (step length; stride angle, height, frequency, and contact time; swing time; contact phase; support phase; push-off phase) parameters were measured during two incremental treadmill running tests performed two days apart after an exhaustive training session. When running at 14 km/h and 16 km/h, the Tecar treatment group presented greater increases in stride length (p < 0.001), angle (p < 0.05) and height (p < 0.001) between the first and second tests than the control group and, accordingly, greater decreases in stride frequency (p < 0.05). Physiological parameters were similar between groups. The present study suggests that a Tecar therapy intervention enhances biomechanical parameters in recreational runners after an exhaustive training session more than passive rest, generating a more efficient running pattern without affecting selected physiological parameters. Copyright © 2018 Elsevier Ltd. All rights reserved.

Evaluation of corneal biomechanics in patients with keratectasia following LASIK using dynamic Scheimpflug analyzer.

PubMed

Ueki, Ryotaro; Maeda, Naoyuki; Fuchihata, Mutsumi; Asai, Tomoko; Koh, Shizuka; Fujimoto, Hisataka; Uematsu, Masafumi; Nishida, Kohji

2018-04-26

To investigate the corneal biomechanics in eyes with keratectasia following LASIK using a dynamic Scheimpflug analyzer. Case-Control study. The subjects in the study included 12 eyes with keratectasia after LASIK (KE), 24 eyes with keratoconus (KC), 17 eyes without keratectasia after LASIK (LASIK), and 34 eyes with normal corneas (Normal). Corneal biomechanics of the four groups were evaluated using a dynamic Scheimpflug analyzer. Compared with Normal (7.06 ± 0.54), the radius at the highest concavity (radius, mm) of LASIK (5.96 ± 0.76), KE (4.93 ± 0.61) and KC (5.39 ± 1.02) were significantly small. The Deflection Amplitude (HCDLA, mm) of Normal (0.94 ± 0.07) was significantly lower than those of KE (1.11 ± 0.10) and KC (1.06 ± 0.16), and was not significantly different from that of LASIK (0.98 ± 0.07). There were significant differences between LASIK and KE in radius and HCDLA (P < 0.05), whereas KE and KC had no differences in these parameters. Corneal biomechanical features evaluated using the dynamic Scheimpflug analyzer suggest that biomechanical properties in eyes with keratectasia, keratoconus, and LASIK are different from those of normal eyes. Although the biomechanics in eyes with keratectasia differs from that in eyes with LASIK, it is similar to that in eyes with keratoconus.

In vitro method for assessing the biomechanics of the patellofemoral joint following total knee arthroplasty.

PubMed

Coles, L G; Gheduzzi, S; Miles, A W

2014-12-01

The patellofemoral joint is a common site of pain and failure following total knee arthroplasty. A contributory factor may be adverse patellofemoral biomechanics. Cadaveric investigations are commonly used to assess the biomechanics of the joint, but are associated with high inter-specimen variability and often cannot be carried out at physiological levels of loading. This study aimed to evaluate the suitability of a novel knee simulator for investigating patellofemoral joint biomechanics. This simulator specifically facilitated the extended assessment of patellofemoral joint biomechanics under physiological levels of loading. The simulator allowed the knee to move in 6 degrees of freedom under quadriceps actuation and included a simulation of the action of the hamstrings. Prostheses were implanted on synthetic bones and key soft tissues were modelled with a synthetic analogue. In order to evaluate the physiological relevance and repeatability of the simulator, measurements were made of the quadriceps force and the force, contact area and pressure within the patellofemoral joint using load cells, pressure-sensitive film, and a flexible pressure sensor. The results were in agreement with those previously reported in the literature, confirming that the simulator is able to provide a realistic physiological loading situation. Under physiological loading, average standard deviations of force and area measurements were substantially lower and comparable to those reported in previous cadaveric studies, respectively. The simulator replicates the physiological environment and has been demonstrated to allow the initial investigation of factors affecting patellofemoral biomechanics following total knee arthroplasty. © IMechE 2014.

The effect of trochlear dysplasia on patellofemoral biomechanics: a cadaveric study with simulated trochlear deformities.

PubMed

Van Haver, Annemieke; De Roo, Karel; De Beule, Matthieu; Labey, Luc; De Baets, Patrick; Dejour, David; Claessens, Tom; Verdonk, Peter

2015-06-01

Trochlear dysplasia appears in different geometrical variations. The Dejour classification is widely used to grade the severity of trochlear dysplasia and to decide on treatment. To investigate the effect of trochlear dysplasia on patellofemoral biomechanics and to determine if different types of trochlear dysplasia have different effects on patellofemoral biomechanics. Controlled laboratory study. Trochlear dysplasia was simulated in 4 cadaveric knees by replacing the native cadaveric trochlea with different types of custom-made trochlear implants, manufactured with 3-dimensional printing. For each knee, 5 trochlear implants were designed: 1 implant simulated the native trochlea (control condition), and 4 implants simulated 4 types of trochlear dysplasia. The knees were subjected to 3 biomechanical tests: a squat simulation, an open chain extension simulation, and a patellar stability test. The patellofemoral kinematics, contact area, contact pressure, and stability were compared between the control condition (replica implants) and the trochlear dysplastic condition and among the subgroups of trochlear dysplasia. The patellofemoral joint in the trochlear dysplastic group showed increased internal rotation, lateral tilt, and lateral translation; increased contact pressures; decreased contact areas; and decreased stability when compared with the control group. Within the trochlear dysplastic group, the implants graded as Dejour type D showed the largest deviations for the kinematical parameters, and the implants graded as Dejour types B and D showed the largest deviations for the patellofemoral contact areas and pressures. Patellofemoral kinematics, contact area, contact pressure, and stability are significantly affected by trochlear dysplasia. Of all types of trochlear dysplasia, the models characterized with a pronounced trochlear bump showed the largest deviations in patellofemoral biomechanics. Investigating the relationship between the shape of the trochlea and patellofemoral biomechanics can provide insight into the short-term effects (maltracking, increased pressures, and instability) and long-term effects (osteoarthritis) of different types of trochlear dysplasia. Furthermore, this investigation provides an empirical explanation for better treatment outcomes of trochleoplasty for Dejour types B and D dysplasia. © 2015 The Author(s).

Biomechanical Analysis of Lateral Lumbar Interbody Fusion Constructs with Various Fixation Options: Based on a Validated Finite Element Model.

PubMed

Zhang, Zhenjun; Fogel, Guy R; Liao, Zhenhua; Sun, Yitao; Liu, Weiqiang

2018-06-01

Lateral lumbar interbody fusion using cage supplemented with fixation has been used widely in the treatment of lumbar disease. A combined fixation (CF) of lateral plate and spinous process plate may provide multiplanar stability similar to that of bilateral pedicle screws (BPS) and may reduce morbidity. The biomechanical influence of the CF on cage subsidence and facet joint stress has not been well described. The aim of this study was to compare biomechanics of various fixation options and to verify biomechanical effects of the CF. The surgical finite element models with various fixation options were constructed based on computed tomography images. The lateral plate and posterior spinous process plate were applied (CF). The 6 motion modes were simulated. Range of motion (ROM), cage stress, endplate stress, and facet joint stress were compared. For the CF model, ROM, cage stress, and endplate stress were the minimum in almost all motion modes. Compared with BPS, the CF reduced ROM, cage stress, and endplate stress in all motion modes. The ROM was reduced by more than 10% in all motion modes except for flexion; cage stress and endplate stress were reduced more than 10% in all motion modes except for rotation-left. After interbody fusion, facet joint stress was reduced substantially compared with the intact conditions in all motion modes except for flexion. The combined plate fixation may offer an alternative to BPS fixation in lateral lumbar interbody fusion. Copyright © 2018 Elsevier Inc. All rights reserved.

Biomechanical Profiles When Towing a Sled and Wearing a Weighted Vest Once Cleared for Sports Post-ACL Reconstruction.

PubMed

Hartigan, Erin; Lawrence, Michael; Murray, Thomas; Shaw, Bernadette; Collins, Erin; Powers, Kaitlin; Townsend, James

2016-09-01

Though rehabilitation attempts to correct "stiff knee gait" and control for dynamic limb valgus after anterior cruciate ligament reconstruction (ACLR), impaired biomechanics often persist when an individual is cleared to return to sport (RTS). Reduced knee extension moments (KEMs) and knee flexion angles (KFAs) often continue. While at the hip, increased hip adduction angles (HADDAs) and hip internal rotation angles (HIRAs) often persist in spite of dynamic hip stabilization exercises. Sled towing and weighted vest tasks increase KEM and hip extension moments (HEMs) in healthy individuals, yet biomechanical profiles during these tasks after ACLR are unknown. Weighted gait will increase KEM, HEM, hip abduction moments (HABDMs), and hip external rotation moments (HERMs) and will not increase unwanted biomechanics (limb asymmetries, HIRA, HADDA) compared with normal gait. Controlled laboratory study. Level 4. Fourteen men and 24 women who were 5 to 12 months after ACLR, had no concomitant ligament injuries, and were cleared to RTS were recruited. Sexes were evaluated independently given the sex-specific incidence to ACL injury, reinjury, and gait responses to certain interventions. Joint moment impulses and peak angles over the first 25% of stance were compared between limbs and across tasks (eg, unweighted gait, sled 50% body weight [BW], and vest 50% BW). Men showed that weighted gait increased KEM, HEM, HERM, HADBM (vest only), HADDA, HIRA (sled only), and KFA. Asymmetrical KEM and KFA existed across tasks. Women showed that weighted gait increased KEM, HEM, HERM, HADBM (vest only), HFA (sled only), HADDA, and KFA. Asymmetrical KEM, HEM, HIRA, and KFA (sled only) existed across tasks. Weighted gait generally increased joint moments. Unwanted biomechanics were unique for each weighted gait task. Though joint moments increased, both tasks created unwanted biomechanics after ACLR. Persistent hip (women only) and KEM asymmetries across tasks when cleared to RTS are concerning given the relationship among these biomechanics and decreased functional performance. © 2016 The Author(s).

Role of Aquaporin 0 in lens biomechanics.

PubMed

Sindhu Kumari, S; Gupta, Neha; Shiels, Alan; FitzGerald, Paul G; Menon, Anil G; Mathias, Richard T; Varadaraj, Kulandaiappan

2015-07-10

Maintenance of proper biomechanics of the eye lens is important for its structural integrity and for the process of accommodation to focus near and far objects. Several studies have shown that specialized cytoskeletal systems such as the beaded filament (BF) and spectrin-actin networks contribute to mammalian lens biomechanics; mutations or deletion in these proteins alters lens biomechanics. Aquaporin 0 (AQP0), which constitutes ∼45% of the total membrane proteins of lens fiber cells, has been shown to function as a water channel and a structural cell-to-cell adhesion (CTCA) protein. Our recent ex vivo study on AQP0 knockout (AQP0 KO) mouse lenses showed the CTCA function of AQP0 could be crucial for establishing the refractive index gradient. However, biomechanical studies on the role of AQP0 are lacking. The present investigation used wild type (WT), AQP5 KO (AQP5(-/-)), AQP0 KO (heterozygous KO: AQP0(+/-); homozygous KO: AQP0(-/-); all in C57BL/6J) and WT-FVB/N mouse lenses to learn more about the role of fiber cell AQPs in lens biomechanics. Electron microscopic images exhibited decreases in lens fiber cell compaction and increases in extracellular space due to deletion of even one allele of AQP0. Biomechanical assay revealed that loss of one or both alleles of AQP0 caused a significant reduction in the compressive load-bearing capacity of the lenses compared to WT lenses. Conversely, loss of AQP5 did not alter the lens load-bearing ability. Compressive load-bearing at the suture area of AQP0(+/-) lenses showed easy separation while WT lens suture remained intact. These data from KO mouse lenses in conjunction with previous studies on lens-specific BF proteins (CP49 and filensin) suggest that AQP0 and BF proteins could act co-operatively in establishing normal lens biomechanics. We hypothesize that AQP0, with its prolific expression at the fiber cell membrane, could provide anchorage for cytoskeletal structures like BFs and together they help to confer fiber cell shape, architecture and integrity. To our knowledge, this is the first report identifying the involvement of an aquaporin in lens biomechanics. Since accommodation is required in human lenses for proper focusing, alteration in the adhesion and/or water channel functions of AQP0 could contribute to presbyopia. Copyright © 2015 Elsevier Inc. All rights reserved.

Biomechanical Comparisons Among Fastball, Slider, Curveball, and Changeup Pitch Types and Between Balls and Strikes in Professional Baseball Pitchers.

PubMed

Escamilla, Rafael F; Fleisig, Glenn S; Groeschner, Dave; Akizuki, Ken

2017-12-01

In professional baseball pitchers, pitching biomechanics have not been examined for the slider, and the only known study for the curveball and changeup examined limited kinetics. Moreover, no known studies have investigated pitching biomechanics between strikes and balls. Purpose/Hypothesis: The purpose was to compare pitching biomechanics in professional baseball pitchers among the fastball, slider, curveball, and changeup and between balls and strikes. It was hypothesized that pitching kinematics and kinetics would be similar among the slider, fastball, and curveball; shoulder and elbow forces and torques would be significantly lower in the changeup; and pitching biomechanics would be similar between balls and strikes. Controlled laboratory study. Among 18 professional baseball pitchers, 38 reflective markers were positioned on the body and each player threw 32 to 40 maximum effort pitches-consisting of the fastball, curveball, slider, and changeup pitch types-from a regulation mound to a catcher. The markers were tracked by 18 high-speed 180-Hz cameras, and data were processed and run through a computer program to calculate 25 kinematic parameters, 7 kinetic parameters, and 4 temporal parameters for each pitch type and for both strikes and balls. A 2-way repeated-measures analysis of variance ( P < .01) was used to assess pitching biomechanical differences among pitch type and pitch result (balls vs strikes). During arm cocking, elbow varus torque was 8% to 9% greater in the fastball and slider compared with the changeup, shoulder horizontal adduction torque was 17% to 20% greater in the slider and curveball compared with the changeup, and shoulder anterior force was 13% greater in the curveball compared with the changeup. During arm deceleration, elbow flexor torque was 9% to 14% greater in the fastball compared with the curveball and changeup, and elbow and shoulder proximal forces were 10% to 14% greater in the fastball, slider, and curveball compared with the changeup. At ball release, forward trunk tilt was 16% to 19% greater in the fastball and curveball compared with the changeup, contralateral trunk tilt was 26% to 41% greater in the curveball compared with the slider and changeup, knee flexion was 18% greater in the changeup compared with the fastball, and the knee extended 7° more from lead foot contact to ball release in the fastball compared with the changeup. During arm cocking, pelvis angular velocity was 7% to 8% greater in the fastball compared with the curveball and changeup, and upper trunk angular velocity was 5% greater in the fastball compared with the changeup. During arm acceleration, shoulder internal rotation angular velocity was 6% to 7% greater in the fastball, slider, and curveball compared with the changeup, and ball velocity at ball release was 11% to 18% greater in the fastball compared with the slider, changeup, and curveball and 6% greater in the slider compared with the curveball. For all the kinematic, kinetic, and temporal parameters, analysis showed no significant differences between balls and strikes and no significant interactions between pitch type and pitch result. Nearly all kinetic differences among pitch types occurred between the changeup and the remaining 3 pitch types. Shoulder and elbow forces and torques and injury risk were greater among the fastball, slider, and curveball compared with the changeup but were similar among the fastball, slider, and curveball. Body segment and joint positions were similar among all pitch types at lead foot contact and at maximum shoulder external rotation; however, at ball release, throwing a fastball and curveball resulted in greater knee extension and more forward and contralateral trunk tilt compared with throwing a changeup and slider. Movement speeds for the pelvis, upper trunk, and shoulder were greatest in the fastball and least in the changeup and were generally similar among the fastball, slider, and curveball. The timing of when pelvis, upper trunk, elbow, and shoulder velocities occurred among the fastball, slider, curveball, and changeup was similar, and no kinematic or kinetic differences were noted between throwing balls and strikes. The results from the current study will help clinicians understand differences in pitching biomechanics in professional baseball pitchers among the fastball, slider, curveball, and changeup; the study provides limited insight into shoulder and elbow injury risk associated with different types of pitches.

The short-term effects of running on the deformation of knee articular cartilage and its relationship to biomechanical loads at the knee.

PubMed

Boocock, M; McNair, P; Cicuttini, F; Stuart, A; Sinclair, T

2009-07-01

To investigate the short-term effects of recreational running on the deformation of knee articular cartilage and to examine the relationship between changes in knee cartilage volume and biomechanical modulators of knee joint load. Twenty healthy volunteers participated in a two phase cross-sectional study. Session 1 involved Magnetic Resonance Imaging (MRI) of femoral and tibial cartilage volumes prior to and following a 30 min period of relaxed sitting, which was directly followed by a recreational run of 5000 steps. Subsequently, all participants undertook a laboratory study of their running gait to compare biomechanical derived measures of knee joint loading with changes in cartilage volume. Estimates of knee joint load were determined using a rigid-link segment, dynamic biomechanical model of the lower limbs and a simplified muscle model. Running resulted in significant deformation of the medial (5.3%, P<0.01) and lateral femoral cartilage (4.0%, P<0.05) and lateral aspect of the tibial cartilage (5.7%, P<0.01), with no significant differences between genders. Maximum compression stress was significantly correlated with percentage changes in lateral femoral cartilage volume (r(2)=0.456, P<0.05). No other biomechanical variables correlated with volume changes. Limited evidence was found linking biomechanical measures of knee joint loading and observed short-term deformation of knee articular cartilage volume following running. Further enhancement of knee muscle modelling and analysis of stress distribution across cartilage are needed if we are to fully understand the contribution of biomechanical factors to knee joint loading and the pathogenesis of knee osteoarthritis (OA).

The effect of foot landing position on biomechanical risk factors associated with anterior cruciate ligament injury.

PubMed

Tran, Andrew A; Gatewood, Corey; Harris, Alex H S; Thompson, Julie A; Dragoo, Jason L

2016-12-01

Identification of biomechanical risk factors associated with anterior cruciate ligament (ACL) injury can facilitate injury prevention. The purpose of this study is to investigate the effects of three foot landing positions, "toe-in", "toe-out" and "neutral", on biomechanical risk factors for ACL injury in males and females. The authors hypothesize that 1) relative to neutral, the toe-in position increases the biomechanical risk factors for ACL injury, 2) the toe-out position decreases these biomechanical risk factors, and 3) compared to males, females demonstrate greater changes in lower extremity biomechanics with changes in foot landing position. Motion capture data on ten male and ten female volunteers aged 20-30 years (26.4 ± 2.50) were collected during double-leg jump landing activities. Subjects were asked to land on force plates and target one of three pre-templated foot landing positions: 0° ("neutral"), 30° internal rotation ("toe-in"), and 30° external rotation ("toe-out") along the axis of the anatomical sagittal plane. A mixed-effects ANOVA and pairwise Tukey post-hoc comparison were used to detect differences in kinematic and kinetic variables associated with biomechanical risk factors of ACL injury between the three foot landing positions. Relative to neutral, landing in the toe-in position increased peak hip adduction, knee internal rotation angles and moments (p < 0.01), and peak knee abduction angle (p < 0.001). Landing in the toe-in position also decreased peak hip flexion angle (p < 0.001) and knee flexion angle (p = 0.023). Landing in the toe-out position decreased peak hip adduction, knee abduction, and knee internal rotation angles (all p < 0.001). Male sex was associated with a smaller increase in hip adduction moment (p = 0.043) and knee internal rotation moment (p = 0.032) with toe-in landing position compared with female sex. Toe-in landing position exacerbates biomechanical risk factors associated with ACL injury, while toe-out landing position decreases these factors.

Assessment of a novel biomechanical fracture model for distal radius fractures

PubMed Central

2012-01-01

Background Distal radius fractures (DRF) are one of the most common fractures and often need surgical treatment, which has been validated through biomechanical tests. Currently a number of different fracture models are used, none of which resemble the in vivo fracture location. The aim of the study was to develop a new standardized fracture model for DRF (AO-23.A3) and compare its biomechanical behavior to the current gold standard. Methods Variable angle locking volar plates (ADAPTIVE, Medartis) were mounted on 10 pairs of fresh-frozen radii. The osteotomy location was alternated within each pair (New: 10 mm wedge 8 mm / 12 mm proximal to the dorsal / volar apex of the articular surface; Gold standard: 10 mm wedge 20 mm proximal to the articular surface). Each specimen was tested in cyclic axial compression (increasing load by 100 N per cycle) until failure or −3 mm displacement. Parameters assessed were stiffness, displacement and dissipated work calculated for each cycle and ultimate load. Significance was tested using a linear mixed model and Wald test as well as t-tests. Results 7 female and 3 male pairs of radii aged 74 ± 9 years were tested. In most cases (7/10), the two groups showed similar mechanical behavior at low loads with increasing differences at increasing loads. Overall the novel fracture model showed a significant different biomechanical behavior than the gold standard model (p < 0,001). The average final loads resisted were significantly lower in the novel model (860 N ± 232 N vs. 1250 N ± 341 N; p = 0.001). Conclusion The novel biomechanical fracture model for DRF more closely mimics the in vivo fracture site and shows a significantly different biomechanical behavior with increasing loads when compared to the current gold standard. PMID:23244634

A biomechanical comparison of the Rogers interspinous and the Lovely-Carl tension band wiring techniques for fixation of the cervical spine.

PubMed

Brasil, A V; Coehlo, D G; Filho, T E; Braga, F M

2000-07-01

The authors conducted a biomechanical study in which they compared the uses of the Rogers interspinous and the Lovely-Carl tension band wiring techniques for internal fixation of the cervical spine. An extensive biomechanical evaluation (stiffness in positive and negative rotations around the x, y, and z axes; range of motion in flexion-extension, bilateral axial rotation, and bilateral bending; and neutral zone in flexion-extension, bilateral axial rotation, and lateral bending to the right and to the left) was performed in two groups of intact calf cervical spines. After these initial tests, all specimens were subjected to a distractive flexion Stage 3 ligamentous lesion. Group 1 specimens then underwent surgical fixation by the Rogers technique, and Group 2 specimens underwent surgery by using the Lovely-Carl technique. After fixation, specimens were again submitted to the same biomechanical evaluation. The percentage increase or decrease between the pre- and postoperative parameters was calculated. These values were considered quantitative indicators of the efficacy of the techniques, and the efficacy of the two techniques was compared. Analysis of the findings demonstrated that in the spines treated with the Lovely-Carl technique less restriction of movement was produced without affecting stiffness, compared with those treated with the Rogers technique, thus making the Lovely-Carl technique clinically less useful.

Partial articular-sided rotator cuff tears: in situ repair versus tear completion prior to repair.

PubMed

Sethi, Paul M; Rajaram, Arun; Obopilwe, Elifho; Mazzocca, Augustus D

2013-06-01

Uncertainty exists over the ideal surgical treatment method for partial articular-sided rotator cuff tears, with options ranging from debridement to in situ repair to tear completion prior to repair. The purpose of this study was to determine whether in situ repair was a viable biomechanical treatment option compared with tear completion prior to repair of partial articular-sided rotator cuff tears. Fourteen fresh-frozen cadaveric shoulders were dissected. Partial articular-sided tears were created and repaired using in situ repair or tear completion prior to the repair. Strain and displacement were measured at 45°, 60°, and 90° of glenohumeral abduction. Testing was performed with a load of 100 N applied for 30 cycles. Data from the biomechanical testing displayed 4 conditions that showed improved characteristics of in situ repair over completion and repair: bursal-sided strain anteriorly at 45°, bursal-sided strain anteriorly at 90°, bursal-sided displacement anteriorly at 45°, and bursal-sided displacement anteriorly at 90°. The data indicate that in situ repair is a viable biomechanical treatment option compared with tear completion prior to repair of partial articular-sided rotator cuff tears. When clinically appropriate, the in situ repair may offer some biomechanical advantages, with lower strain and displacement observed on the bursal side compared with tear completion prior to repair. Copyright 2013, SLACK Incorporated.

Comparative biomechanical effectiveness of over-the-counter devices for individuals with a flexible flatfoot secondary to forefoot varus.

PubMed

Hurd, Wendy J; Kavros, Steven J; Kaufman, Kenton R

2010-11-01

Evaluate effects of a new off-the-shelf insert on frontal plane foot biomechanics and compare effectiveness of the new and an existing off-the-shelf insert and a motion-control shoe in neutralizing frontal plane foot biomechanics. Descriptive. Biomechanics laboratory. Fifteen uninjured subjects with a flexible flatfoot secondary to forefoot varus. Three-dimensional kinematic and kinetic data were collected as subjects walked and jogged at their self-selected speed while wearing a motion-control running shoe, the shoe with a new off-the-shelf insert, and the shoe with an existing off-the-shelf insert. Frontal plane kinematics and rearfoot kinetics were evaluated during stance. Statistical analysis was performed using a repeated measures analysis of variance and Student-Newman-Keuls post hoc tests (α ≤ 0.05). The new insert and motion-control shoe placed the forefoot in a less-everted position than the existing off-the-shelf insert during walking. There were no differences in forefoot kinematics during jogging, nor were there differences in rearfoot motion during walking or jogging. The rearfoot eversion moment was significantly lower with the new off-the-shelf insert compared with the motion-control shoe and the existing insert during walking and jogging. A new off-the-shelf device is available that promotes more neutral frontal plane biomechanics, thus providing a theoretical rationale for using this device for injury prevention and treatment. The comparative biomechanical effectiveness of a motion-control shoe and the orthotic inserts may assist health care professionals in selecting a device to correct the flatfoot structure.

Finite Element Study of a Lumbar Intervertebral Disc Nucleus Replacement Device.

PubMed

Coogan, Jessica S; Francis, W Loren; Eliason, Travis D; Bredbenner, Todd L; Stemper, Brian D; Yoganandan, Narayan; Pintar, Frank A; Nicolella, Daniel P

2016-01-01

Nucleus replacement technologies are a minimally invasive alternative to spinal fusion and total disc replacement that have the potential to reduce pain and restore motion for patients with degenerative disc disease. Finite element modeling can be used to determine the biomechanics associated with nucleus replacement technologies. The current study focuses on a new nucleus replacement device designed as a conforming silicone implant with an internal void. A validated finite element model of the human lumbar L3-L4 motion segment was developed and used to investigate the influence of the nucleus replacement device on spine biomechanics. In addition, the effect of device design changes on biomechanics was determined. A 3D, L3-L4 finite element model was constructed from medical imaging data. Models were created with the normal intact nucleus, the nucleus replacement device, and a solid silicone implant. Probabilistic analysis was performed on the normal model to provide quantitative validation metrics. Sensitivity analysis was performed on the silicone Shore A durometer of the device. Models were loaded under axial compression followed by flexion/extension, lateral bending, or axial rotation. Compressive displacement, endplate stresses, reaction moment, and annulus stresses were determined and compared between the different models. The novel nucleus replacement device resulted in similar compressive displacement, endplate stress, and annulus stress and slightly higher reaction moment compared with the normal nucleus. The solid implant resulted in decreased displacement, increased endplate stress, decreased annulus stress, and decreased reaction moment compared with the novel device. With increasing silicone durometer, compressive displacement decreased, endplate stress increased, reaction moment increased, and annulus stress decreased. Finite element analysis was used to show that the novel nucleus replacement device results in similar biomechanics compared with the normal intact nucleus.

Finite Element Study of a Lumbar Intervertebral Disc Nucleus Replacement Device

PubMed Central

Coogan, Jessica S.; Francis, W. Loren; Eliason, Travis D.; Bredbenner, Todd L.; Stemper, Brian D.; Yoganandan, Narayan; Pintar, Frank A.; Nicolella, Daniel P.

2016-01-01

Nucleus replacement technologies are a minimally invasive alternative to spinal fusion and total disc replacement that have the potential to reduce pain and restore motion for patients with degenerative disc disease. Finite element modeling can be used to determine the biomechanics associated with nucleus replacement technologies. The current study focuses on a new nucleus replacement device designed as a conforming silicone implant with an internal void. A validated finite element model of the human lumbar L3–L4 motion segment was developed and used to investigate the influence of the nucleus replacement device on spine biomechanics. In addition, the effect of device design changes on biomechanics was determined. A 3D, L3–L4 finite element model was constructed from medical imaging data. Models were created with the normal intact nucleus, the nucleus replacement device, and a solid silicone implant. Probabilistic analysis was performed on the normal model to provide quantitative validation metrics. Sensitivity analysis was performed on the silicone Shore A durometer of the device. Models were loaded under axial compression followed by flexion/extension, lateral bending, or axial rotation. Compressive displacement, endplate stresses, reaction moment, and annulus stresses were determined and compared between the different models. The novel nucleus replacement device resulted in similar compressive displacement, endplate stress, and annulus stress and slightly higher reaction moment compared with the normal nucleus. The solid implant resulted in decreased displacement, increased endplate stress, decreased annulus stress, and decreased reaction moment compared with the novel device. With increasing silicone durometer, compressive displacement decreased, endplate stress increased, reaction moment increased, and annulus stress decreased. Finite element analysis was used to show that the novel nucleus replacement device results in similar biomechanics compared with the normal intact nucleus. PMID:27990418

Identification of biomechanical properties of the cornea: the ocular response analyzer.

PubMed

Terai, Naim; Raiskup, Frederik; Haustein, Michael; Pillunat, Lutz E; Spoerl, Eberhard

2012-07-01

Several methods have been devised for measuring geometric parameters of the cornea but, until now, the biomechanics of the cornea have been largely ignored. The relatively new Ocular Response Analyzer (ORA) provides such biomechanical information. In order to correctly interpret the underlying biomechanics of ORA data, we review reported ORA measurements and provide a compendium of factors influencing these measurements, with discussion of possible explanations for ORA measurement results. This review comprised a literature search using "ocular response analyzer" and "ocular response analyser" as keywords. We reviewed and compared reported results from recent ORA studies so obtained, with an eye to understanding corneal biomechanics. Several ORA biomechanical parameters of the cornea - corneal hysteresis (CH) and corneal resistant factor (CRF) - characterize the viscoelastic properties of the cornea, especially those of the ground substance. The impact on CH and CRF values of various independent factors, e.g. intraocular pressure (IOP), age, central corneal thickness (CCT), and corneal swelling, are discussed. The impact on CH and CRF of treatment-related structural changes of the cornea, i.e. those occurring after refractive surgical procedures, placement of intracorneal rings, and collagen crosslinking (CXL), as well as pathological changes of the cornea, e.g. those resulting from keratoconus, edema, and glaucoma, are discussed. Changes in CRF and CH may be reflective of structural changes in the ground substance of the cornea. Thus, ORA provides invaluable information for delineating biomechanical conditions pertaining to the cornea, with special regard to ocular diseases, e.g. keratoconus and glaucoma.

Biomechanical analysis of four different fixations for the posterolateral shearing tibial plateau fracture.

PubMed

Zhang, Wei; Luo, Cong-Feng; Putnis, Sven; Sun, Hui; Zeng, Zhi-Min; Zeng, Bing-Fang

2012-03-01

The posterolateral shearing tibial plateau fracture is uncommon in the literature, however with the increased usage of computer tomography (CT), the incidence of these fractures is no longer as low as previously thought. Few studies have concentrated on this fracture, least of all using a biomechanical model. The purpose of this study was to compare and analyse the biomechanical characteristics of four different types of internal fixation to stabilise the posterolateral shearing tibial plateau fracture. Forty synthetic tibiae (Synbone, right) simulated the posterolateral shearing fracture models and these were randomly assigned into four groups; Group A was fixed with two anterolateral lag screws, Group B with an anteromedial Limited Contact Dynamic Compression Plate (LC-DCP), Group C with a lateral locking plate, and Group D with a posterolateral buttress plate. Vertical displacement of the posterolateral fragment was measured using three different strengths of axial loading force, and finally loaded until fixation failure. It was concluded that the posterolateral buttress plate is biomechanically the strongest fixation method for the posterolateral shearing tibial plateau fracture. Copyright © 2011 Elsevier B.V. All rights reserved.

The Relationship between MR Parameters and Biomechanical Quantities of Loaded Human Articular Cartilage in Osteoarthritis: An In-Vitro Study

NASA Astrophysics Data System (ADS)

Juráš, V.; Szomolányi, P.; Gäbler, S.; Frollo, I.; Trattnig, S.

2009-01-01

The aim of this study was to assess the changes in MRI parameters during applied load directly in MR scanner and correlate these changes with biomechanical parameters of human articular cartilage. Cartilage explants from patients who underwent total knee replacement were examined in the micro-imaging system in 3T scanner. Respective MRI parameters (T1 without- and T1 with contrast agent as a marker of proteoglycan content, T2 as a marker of collagen network anisotropy and ADC as a measure of diffusivity) were calculated in pre- and during compression state. Subsequently, these parameters were compared to the biomechanical properties of articular cartilage, instantaneous modulus (I), equilibrium modulus (Eq) and time of tissue relaxation (τ). Significant load-induced changes of T2 and ADC were recorded. High correlation between T1Gd and I (r = 0.6324), and between ADC and Eq (r = -0.4884) was found. Multi-parametric MRI may have great potential in analyzing static and dynamic biomechanical behavior of articular cartilage in early stages of osteoarthritis (OA).

Shoe drop reduction influences the lower limb biomechanics of children tennis players during an open stance forehand: A longitudinal study.

PubMed

Herbaut, Alexis; Simoneau-Buessinger, Emilie; Barbier, Franck; Gillet, Christophe; Roux, Maxime; Guéguen, Nils; Chavet, Pascale

2017-11-01

Compared to traditional tennis shoes, using 0-drop shoes was shown to induce an immediate switch from rear- to forefoot strike pattern to perform an open stance tennis forehand for 30% of children tennis players. The purpose of the study was to examine the long-term effects of a gradual reduction in the shoe drop on the biomechanics of children tennis players performing open stance forehands. Thirty children tennis players participated in 2 laboratory biomechanical test sessions (intermediate: +4 months and final: +8 months) after an inclusion visit where they were randomly assigned to control (CON) or experimental (EXP) group. CON received 12-mm-drop shoes twice, whereas EXP received 8 mm then 4-mm-drop shoes. Strike index indicated that all CON were rearfoot strikers in intermediate and final test sessions. All EXP were rearfoot strikers in intermediate test session, but half the group switched towards a forefoot strike pattern in final test session. This switch resulted in a decreased loading rate of the ground reaction force (-73%, p = .005) but increased peak ankle plantarflexors moment (+47%, p = .050) and peak ankle power absorption (+107%, p = .005) for these participants compared with CON. Biomechanical changes associated with the long-term use of partial minimalist shoes suggest a reduction in heel compressive forces but an increase in Achilles tendon tensile forces.

Finite Element Analysis of the Cingulata Jaw: An Ecomorphological Approach to Armadillo’s Diets

PubMed Central

Serrano-Fochs, Sílvia; De Esteban-Trivigno, Soledad; Marcé-Nogué, Jordi; Fortuny, Josep; Fariña, Richard A.

2015-01-01

Finite element analyses (FEA) were applied to assess the lower jaw biomechanics of cingulate xenarthrans: 14 species of armadillos as well as one Pleistocene pampathere (11 extant taxa and the extinct forms Vassallia, Eutatus and Macroeuphractus). The principal goal of this work is to comparatively assess the biomechanical capabilities of the mandible based on FEA and to relate the obtained stress patterns with diet preferences and variability, in extant and extinct species through an ecomorphology approach. The results of FEA showed that omnivorous species have stronger mandibles than insectivorous species. Moreover, this latter group of species showed high variability, including some similar biomechanical features of the insectivorous Tolypeutes matacus and Chlamyphorus truncatus to those of omnivorous species, in agreement with reported diets that include items other than insects. It remains unclear the reasons behind the stronger than expected lower jaw of Dasypus kappleri. On the other hand, the very strong mandible of the fossil taxon Vassallia maxima agrees well with the proposed herbivorous diet. Moreover, Eutatus seguini yielded a stress pattern similar to Vassalia in the posterior part of the lower jaw, but resembling that of the stoutly built Macroeuphractus outesi in the anterior part. The results highlight the need for more detailed studies on the natural history of extant armadillos. FEA proved a powerful tool for biomechanical studies in a comparative framework. PMID:25919313

Mechanical Characterisation and Biomechanical and Biological Behaviours of Ti-Zr Binary-Alloy Dental Implants

PubMed Central

Jiménez-Garrudo, Antonio; Gil-Mur, Francisco Javier; Manero, José María; Punset-Fuste, Miquel; Chávarri-Prado, David; Diéguez-Pereira, Markel; Monticelli, Francesca

2017-01-01

The objective of the study is to characterise the mechanical properties of Ti-15Zr binary alloy dental implants and to describe their biomechanical behaviour as well as their osseointegration capacity compared with the conventional Ti-6Al-4V (TAV) alloy implants. The mechanical properties of Ti-15Zr binary alloy were characterised using Roxolid© implants (Straumann, Basel, Switzerland) via ultrasound. Their biomechanical behaviour was described via finite element analysis. Their osseointegration capacity was compared via an in vivo study performed on 12 adult rabbits. Young's modulus of the Roxolid© implant was around 103 GPa, and the Poisson coefficient was around 0.33. There were no significant differences in terms of Von Mises stress values at the implant and bone level between both alloys. Regarding deformation, the highest value was observed for Ti-15Zr implant, and the lowest value was observed for the cortical bone surrounding TAV implant, with no deformation differences at the bone level between both alloys. Histological analysis of the implants inserted in rabbits demonstrated higher BIC percentage for Ti-15Zr implants at 3 and 6 weeks. Ti-15Zr alloy showed elastic properties and biomechanical behaviours similar to TAV alloy, although Ti-15Zr implant had a greater BIC percentage after 3 and 6 weeks of osseointegration. PMID:29318142

Patellar Tendon Repair Augmentation With a Knotless Suture Anchor Internal Brace: A Biomechanical Cadaveric Study.

PubMed

Rothfeld, Alex; Pawlak, Amanda; Liebler, Stephenie A H; Morris, Michael; Paci, James M

2018-04-01

Patellar tendon repair with braided polyethylene suture alone is subject to knot slippage and failure. Several techniques to augment the primary repair have been described. Purpose/Hypothesis: The purpose was to evaluate a novel patellar tendon repair technique augmented with a knotless suture anchor internal brace with suture tape (SAIB). The hypothesis was that this technique would be biomechanically superior to a nonaugmented repair and equivalent to a standard augmentation with an 18-gauge steel wire. Controlled laboratory study. Midsubstance patellar tendon tears were created in 32 human cadaveric knees. Two comparison groups were created. Group 1 compared #2 supersuture repair without augmentation to #2 supersuture repair with SAIB augmentation. Group 2 compared #2 supersuture repair with an 18-gauge stainless steel cerclage wire augmentation to #2 supersuture repair with SAIB augmentation. The specimens were potted and biomechanically loaded on a materials testing machine. Yield load, maximum load, mode of failure, plastic displacement, elastic displacement, and total displacement were calculated for each sample. Standard statistical analysis was performed. There was a statistically significant increase in the mean ± SD yield load and maximum load in the SAIB augmentation group compared with supersuture alone (mean yield load: 646 ± 202 N vs 229 ± 60 N; mean maximum load: 868 ± 162 N vs 365 ± 54 N; P < .001). Group 2 showed no statistically significant differences between the augmented repairs (mean yield load: 495 ± 213 N vs 566 ± 172 N; P = .476; mean maximum load: 737 ± 210 N vs 697 ± 130 N; P = .721). Patellar tendon repair augmented with SAIB is biomechanically superior to repair without augmentation and is equivalent to repair with augmentation with an 18-gauge stainless steel cerclage wire. This novel patellar tendon repair augmentation is equivalent to standard 18-gauge wire augmentation at time zero. It does not require a second surgery for removal, and it is biomechanically superior to primary repair alone.

BMP-2-regenerated calvarial bone: a biomechanical appraisal in a large animal model.

PubMed

Cray, James; Henderson, Sarah E; Smith, Darren M; Kinsella, Christopher R; Bykowski, Michael; Cooper, Gregory M; Almarza, Alejandro J; Losee, Joseph E

2014-11-01

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is gaining popularity in craniofacial applications. Calvarial defects are, under normal circumstances, subjected to only minimal levels of the biomechanical stresses known to play an important role in osteogenesis, yet regenerated calvarial bone must be capable of withstanding traumatic forces such that the underlying neurocapsule is protected. The aim of this study is to, for the first time, assess the biomechanical properties of calvarial bone regenerated with derivations of a commercially available rhBMP-2-based system. Standardized calvarial defects were created in 23 adult male canines. These defects were treated with rhBMP-2 on one of several carriers. After 24 weeks, the biomechanical properties of the rhBMP-2-generated bone were compared to those of controls with a modified punch-out test (Bluehill 2; Instron, Norwood, Mass) and compared using a paired nonparametric analyses (SPSS, 17.0, Chicago, Ill). In a previously published report, defects across all the rhBMP-2 therapy groups were observed to have a mean rate of 99.5% radio-opacity at 24 weeks indicating nearly full bony coverage of the calvarial defect (compared to 32.7% in surgical controls). For ultimate load, ultimate energy, and first peak energy, there were significant differences (P<0.05) with the control native bone having more robust biomechanical properties than the rhBMP-2-generated bone. We conclude from these findings that rhBMP-2-generated calvarial bone is significantly less protective against trauma than native bone at 6 months. Further investigation is required to assess the efficacy of rhBMP-2 in healing calvarial defects in the longer term.

Biomechanical Properties of a Novel Biodegradable Magnesium-Based Interference Screw

PubMed Central

Ezechieli, Marco; Meyer, Hanna; Lucas, Arne; Helmecke, Patrick; Becher, Christoph; Calliess, Tilman; Windhagen, Henning; Ettinger, Max

2016-01-01

Magnesium-based interference screws may be an alternative in anterior/posterior cruciate ligament reconstruction. The well-known osteoconductive effects of biodegradable magnesium alloys may be useful. It was the purpose of this study to evaluate the biomechanical properties of a magnesium based interference screw and compare it to a standard implant. A MgYREZr-alloy interference screw and a standard implant (Milagro®; De Puy Mitek, Raynham, MA, USA) were used for graft fixation. Specimens were placed into a tensile loading fixation of a servohydraulic testing machine. Biomechanical analysis included pretensioning of the constructs at 20 N for 1 min following cyclic pretensioning of 20 cycles between 20 and 60 N. Biomechanical elongation was evaluated with cyclic loading of 1000 cycles between 50 and 200 N at 0.5 Hz. Maximum load to failure was 511.3±66.5 N for the Milagro® screw and 529.0±63.3 N for magnesium-based screw (ns, P=0.57). Elongations after preload, during cyclical loading and during failure load were not different between the groups (ns, P>0.05). Stiffness was 121.1±13.8 N/mm for the magnesium-based screw and 144.1±18.4 for the Milagro® screw (ns, P=0.32). MgYREZr alloy interference screws show comparable results in biomechanical testing to standard implants and may be an alternative for anterior cruciate reconstruction in the future. PMID:27433303

Tangential Bicortical Locked Fixation Improves Stability in Vancouver B1 Periprosthetic Femur Fractures: A Biomechanical Study.

PubMed

Lewis, Gregory S; Caroom, Cyrus T; Wee, Hwabok; Jurgensmeier, Darin; Rothermel, Shane D; Bramer, Michelle A; Reid, John Spence

2015-10-01

The biomechanical difficulty in fixation of a Vancouver B1 periprosthetic fracture is purchase of the proximal femoral segment in the presence of the hip stem. Several newer technologies provide the ability to place bicortical locking screws tangential to the hip stem with much longer lengths of screw purchase compared with unicortical screws. This biomechanical study compares the stability of 2 of these newer constructs to previous methods. Thirty composite synthetic femurs were prepared with cemented hip stems. The distal femur segment was osteotomized, and plates were fixed proximally with either (1) cerclage cables, (2) locked unicortical screws, (3) a composite of locked screws and cables, or tangentially directed bicortical locking screws using either (4) a stainless steel locking compression plate system with a Locking Attachment Plate (Synthes) or (5) a titanium alloy Non-Contact Bridging system (Zimmer). Specimens were tested to failure in either axial or torsional quasistatic loading modes (n = 3) after 20 moderate load preconditioning cycles. Stiffness, maximum force, and failure mechanism were determined. Bicortical constructs resisted higher (by an average of at least 27%) maximum forces than the other 3 constructs in torsional loading (P < 0.05). Cables constructs exhibited lower maximum force than all other constructs, in both axial and torsional loading. The bicortical titanium construct was stiffer than the bicortical stainless steel construct in axial loading. Proximal fixation stability is likely improved with the use of bicortical locking screws as compared with traditional unicortical screws and cable techniques. In this study with a limited sample size, we found the addition of cerclage cables to unicortical screws may not offer much improvement in biomechanical stability of unstable B1 fractures.

Tangential Bicortical Locked Fixation Improves Stability in Vancouver B1 Periprosthetic Femur Fractures: A Biomechanical Study

PubMed Central

Lewis, Gregory S.; Caroom, Cyrus T.; Wee, Hwabok; Jurgensmeier, Darin; Rothermel, Shane D.; Bramer, Michelle A.; Reid, J. Spence

2015-01-01

Objectives The biomechanical difficulty in fixation of a Vancouver B1 periprosthetic fracture is purchase of the proximal femoral segment in the presence of the hip stem. Several newer technologies provide the ability to place bicortical locking screws tangential to the hip stem with much longer lengths of screw purchase compared to unicortical screws. This biomechanical study compares the stability of two of these newer constructs to previous methods. Methods Thirty composite synthetic femurs were prepared with cemented hip stems. The distal femur segment was osteotomized, and plates were fixed proximally with either: (1) cerclage cables; (2) locked unicortical screws; (3) a composite of locked screws and cables; or tangentially directed bicortical locking screws using either (4) a stainless steel LCP system with a Locking Attachment Plate (Synthes), or (5) a titanium alloy NCB system (Zimmer). Specimens were tested to failure in either axial or torsional quasi-static loading modes (n = 3) after 20 moderate load pre-conditioning cycles. Stiffness, maximum force, and failure mechanism were determined. Results Bicortical constructs resisted higher (by an average of at least 27%) maximum forces than the other three constructs in torsional loading (p<0.05). Cables constructs exhibited lower maximum force than all other constructs, in both axial and torsional loading. The bicortical titanium construct was stiffer than the bicortical stainless steel construct in axial loading. Conclusions Proximal fixation stability is likely improved with the use of bicortical locking screws as compared to traditional unicortical screws and cable techniques. In this study with a limited sample size, we found the addition of cerclage cables to unicortical screws may not offer much improvement in biomechanical stability of unstable B1 fractures. PMID:26053467

A biomechanical comparison in the lower limb and lumbar spine between a hit and drag flick in field hockey.

PubMed

Ng, Leo; Rosalie, Simon M; Sherry, Dorianne; Loh, Wei Bing; Sjurseth, Andreas M; Iyengar, Shrikant; Wild, Catherine Y

2018-03-01

Research has revealed that field hockey drag flickers have greater odds of hip and lumbar injuries compared to non-drag flickers (DF). This study aimed to compare the biomechanics of a field hockey hit and a specialised field hockey drag flick. Eighteen male and seven female specialised hockey DF performed a hit and a drag flick in a motion analysis laboratory with an 18-camera three-dimensional motion analysis system and a calibrated multichannel force platform to examine differences in lower limb and lumbar kinematics and kinetics. Results revealed that drag flicks were performed with more of a forward lunge on the left lower limb resulting in significantly greater left ankle dorsiflexion, knee, hip and lumbar flexion (Ps<0.001) compared to a hit. Drag flicks were also performed with significantly greater lateral flexion (P < 0.002) and rotation of the lumbar spine (P < 0.006) compared to a hit. Differences in kinematics lead to greater shear, compression and tensile forces in multiple left lower limb and lumbar joints in the drag flick compared to the hit (P < 0.05). The biomechanical differences in drag flicks compared to a hit may have ramifications with respect to injury in field hockey drag flickers.

Quadriceps Strength Asymmetry Following ACL Reconstruction Alters Knee Joint Biomechanics and Functional Performance at Time of Return to Activity

PubMed Central

Palmieri-Smith, RM; Lepley, LK

2016-01-01

Background Quadriceps strength deficits are observed clinically following anterior cruciate injury and reconstruction and are often not overcome despite rehabilitation. Given that quadriceps strength may be important for achieving symmetrical joint biomechanics and promoting long-term joint health, determining the magnitude of strength deficits that lead to altered mechanics is critical. Purpose To determine if the magnitude of quadriceps strength asymmetry alters knee and hip biomechanical symmetry, as well as functional performance and self-reported function. Study Design Cross-Sectional study. Methods Seventy-three patients were tested at the time they were cleared for return to activity following ACL reconstruction. Quadriceps strength and activation, scores on the International Knee Documentation Committee form, the hop for distance test, and sagittal plane lower extremity biomechanics were recorded while patients completed a single-legged hop. Results Patients with high and moderate quadriceps strength symmetry had larger central activation ratios as well as greater limb symmetry indices on the hop for distance compared to patients with low quadriceps strength symmetry (P<0.05). Similarly, knee flexion angle and external moment symmetry was higher in the patients with high and moderate quadriceps symmetry compared to those with low symmetry (P<0.05). Quadriceps strength was found to be associated with sagittal plane knee angle and moment symmetry (P<0.05). Conclusion Patients with low quadriceps strength displayed greater movement asymmetries at the knee in the sagittal plane. Quadriceps strength was related to movement asymmetries and functional performance. Rehabilitation following ACL reconstruction needs to focus on maximizing quadriceps strength, which likely will lead to more symmetrical knee biomechanics. PMID:25883169

Biomechanical properties of the forefoot plantar soft tissue as measured by an optical coherence tomography-based air-jet indentation system and tissue ultrasound palpation system.

PubMed

Chao, Clare Y L; Zheng, Yong-Ping; Huang, Yan-Ping; Cheing, Gladys L Y

2010-07-01

The forefoot medial plantar area withstand high plantar pressure during locomotion, and is a common site that develops foot lesion problems among elderly people. The aims of the present study were to (1) determine the correlation between the biomechanical properties of forefoot medial plantar soft tissue measured by a newly developed optical coherence tomography-based air-jet indentation system and by tissue ultrasound palpation system, and (2) to compare the biomechanical properties of plantar soft tissues of medial forefoot between a young and old adult group. Thirty healthy subjects were classified as the young or older group. The biomechanical properties of plantar soft tissues measured at the forefoot by the air-jet indentation system and tissue ultrasound palpation system were performed, and the correlation of the findings obtained in the two systems were compared. A strong positive correlation was obtained from the findings in the two systems (r=0.88, P<0.001). The forefoot plantar soft tissue of the older group was significantly stiffer at the second metatarsal head and thinner at both metatarsal heads than that of the young group (all P<0.05). The stiffness coefficient at the second metatarsal head was 28% greater than that at the first metatarsal head in both study groups. Older subjects showed a loss of elasticity and reduced thickness in their forefoot plantar soft tissue, with the second metatarsal head displaying stiffer and thicker plantar tissue than the first metatarsal head. The air-jet indentation system is a useful instrument for characterizing the biomechanical properties of soft tissue. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Analysis of Biomechanical Effects of Different Sites and Modes of Orthodontic Loading On Arch Expansion in a Preadolescent Mandible: An FEA Study.

PubMed

Haresh, Ajmera Deepal; Pradeep, Singh; Song, Jinlin; Wang, Chao; Fan, Yubo

2018-05-11

The aim of commencing treatment in younger age is to rectify the developing dento-alveolar, skeletal and muscular imbalances. With growing dependence on arch development and expansion, the pendulum is oscillating more towards the non-extraction treatment lately, in resolving constriction and crowding issues. Since, a limited number of attempts have been made for mandibular expansion, this study aimes to evaluate the effect of different modes and sites of loading on the expansion of preadolescent mandible using biomechanics. To address the research purpose, a total of 9 Finite Element models were simulated. Biomechanical response of the mandibular bone and dentition was analyzed under different loading conditions including site and mode, using the simulated FE models. The values of displacement envisaged by the FE models, predict hybrid mode to offer substantial expansion of the mandibular bone as compared to tooth borne and bone borne. In addition, biomechanical effect of site II on mandibular expansion in terms of displacement on X-axis, was significant. In conclusion, the results of our study suggest hybrid mode at site II to be better option for true bony expansion in preadolescent mandible.

Occupant responses in conventional and ABTS seats in high-speed rear sled tests.

PubMed

Viano, David C; Parenteau, Chantal S; Burnett, Roger; Prasad, Priya

2018-01-02

This study compared biomechanical responses of a normally seated Hybrid III dummy on conventional and all belts to seat (ABTS) seats in 40.2 km/h (25 mph) rear sled tests. It determined the difference in performance with modern (≥2000 MY) seats compared to older (<2000 MY) seats and ABTS seats. The seats were fixed in a sled buck subjected to a 40.2 km/h (25 mph) rear sled test. The pulse was a 15 g double-peak acceleration with 150 ms duration. The 50th percentile Hybrid III was lap-shoulder belted in the FMVSS 208 design position. The testing included 11 <2000 MY, 8 ≥2000 MY, and 7 ABTS seats. The dummy was fully instrumented, including head accelerations, upper and lower neck 6-axis load cells, chest acceleration, thoracic and lumbar spine load cells, and pelvis accelerations. The peak responses were normalized by injury assessment reference values (IARVs) to assess injury risks. Statistical analysis was conducted using Student's t test. High-speed video documented occupant kinematics. Biomechanical responses were lower with modern (≥2000 MY) seats than older (<2000 MY) designs. The lower neck extension moment was 32.5 ± 9.7% of IARV in modern seats compared to 62.8 ± 31.6% in older seats (P =.01). Overall, there was a 34% reduction in the comparable biomechanical responses with modern seats. Biomechanical responses were lower with modern seats than ABTS seats. The lower neck extension moment was 41.4 ± 7.8% with all MY ABTS seats compared to 32.5 ± 9.7% in modern seats (P =.07). Overall, the ABTS seats had 13% higher biomechanical responses than the modern seats. Modern (≥2000 MY) design seats have lower biomechanical responses in 40.2 km/h rear sled tests than older (<2000 MY) designs and ABTS designs. The improved performance is consistent with an increase in seat strength combined with improved occupant kinematics through pocketing of the occupant into the seatback, higher and more forward head restraint, and other design changes. The methods and data presented here provide a basis for standardized testing of seats. However, a complete understanding of seat safety requires consideration of out-of-position (OOP) occupants in high-speed impacts and consideration of the much more common, low-speed rear impacts.

Lower limb biomechanics in femoroacetabular impingement syndrome: a systematic review and meta-analysis.

PubMed

King, Matthew G; Lawrenson, Peter R; Semciw, Adam I; Middleton, Kane J; Crossley, Kay M

2018-05-01

(1) Identify differences in hip and pelvic biomechanics in patients with femoroacetabular impingement syndrome (FAIS) compared with controls during everyday activities (eg, walking, squatting); and (2) evaluate the effects of interventions on hip and pelvic biomechanics during everyday activities. Systematic review. Medline, CINAHL, EMBASE, Scopus and SPORTDiscus until February 2017. Primary aim: studies that investigated hip or pelvic kinematics and/or joint torques of everyday activities in patients with FAIS compared with the asymptomatic contralateral limb or a control group. Secondary aim: studies that evaluated effects of conservative or surgical interventions on patients with FAIS using pre-post or controlled clinical trial designs. Biomechanical data must have been collected using three-dimensional motion capture devices. Reporting quality was assessed using the Epidemiological Appraisal Instrument and data were pooled (standardised mean difference (SMD), 95% CI) where populations and primary outcomes were similar. Fourteen studies were included (11 cross-sectional and three pre/post intervention), varying between low and moderate reporting quality. Patients with FAIS walked with a lower: peak hip extension angle (SMD -0.40, 95% CI -0.71 to -0.09), peak internal rotation angle (-0.67, 95% CI -1.19 to -0.16) and external rotation joint torque (-0.71, 95% CI -1.07 to -0.35), and squatted to a lesser depth with no difference in hip flexion range. Pre/post intervention data were limited in number and quality, and to surgical cohorts. This review suggests that patients with FAIS may demonstrate hip biomechanical impairments during walking and squatting, with minimal literature available to comment on other tasks. The information presented in the review provides insight into the biomechanical differences associated with FAIS; however, the between-group differences were small to moderate. This information may aid in the development of management strategies for people with the condition. CRD42016038677. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Sex Differences During an Overhead Squat Assessment.

PubMed

Mauntel, Timothy C; Post, Eric G; Padua, Darin A; Bell, David R

2015-08-01

A disparity exists between the rates of male and female lower extremity injuries. One factor that may contribute to this disparity is high-risk biomechanical patterns that are commonly displayed by females. It is unknown what biomechanical differences exist between males and females during an overhead squat. This study compared lower extremity biomechanics during an overhead squat and ranges of motion between males and females. An electromagnetic motion tracking system interfaced with a force platform was used to quantify peak lower extremity kinematics and kinetics during the descent phase of each squat. Range of motion measurements were assessed with a standard goniometer. Differences between male and female kinematics, kinetics, and ranges of motion were identified with t tests. Males displayed greater peak knee valgus angle, peak hip flexion angle, peak vertical ground reaction forces, and peak hip extension moments. Males also displayed less active ankle dorsiflexion with the knee extended and hip internal and external rotation than females. No other differences were observed. The biomechanical differences between males and females during the overhead squat may result from differences in lower extremity ranges of motion. Therefore, sex-specific injury prevention programs should be developed to improve biomechanics and ranges of motion.

The relationship between corneal biomechanics and anterior segment parameters in the early stage of orthokeratology: A pilot study.

PubMed

Chen, Renai; Mao, Xinjie; Jiang, Jun; Shen, Meixiao; Lian, Yan; Zhang, Bin; Lu, Fan

2017-05-01

To investigate the relationship between corneal biomechanics and anterior segment parameters in the early stage of overnight orthokeratology.Twenty-three eyes from 23 subjects were involved in the study. Corneal biomechanics, including corneal hysteresis (CH) and corneal resistance factor (CRF), and parameters of the anterior segment, including corneal curvature, central corneal thickness (CCT), and corneal sublayers' thickness, were measured at baseline and day 1 and 7 after wearing orthokeratology lens. One-way analysis of variance with repeated measures was used to compare the longitudinal changes and partial least squares linear regression was used to explore the relationship between corneal biomechanics and anterior segment parameters.At baseline, CH and CRF were positively correlated with CCT (r = 0.244, P = .008 for CH; r = 0.249, P < .001 for CRF), central stroma thickness (CST) (r = 0.241, P = .008 for CH; r = 0.244, P = .002 for CRF) and central Bowman layer thickness (CBT) (r = 0.138, P = .039 for CH; r = 0.171, P = .006 for CRF). Both CH and CRF significantly decreased from day 1 after orthokeratology. The corneal curvature and the epithelium thickness also significantly decreased, while the stromal layer thickened significantly from day 1 after orthokeratology. There was no correlation between the changes of corneal biomechanics and anterior segment parameters at day 1 and 7 after orthokeratology.While corneal biomechanics were positively correlated with CCT, CST, and CBT, the changes of CH and CRF were not correlated with the changes of corneal curvature, CCT, and corneal sublayers' thickness in the early stage of orthokeratology in our study.

Determination of torque-limits for human and cat lumbar spine specimens during displacement-controlled physiological motions.

PubMed

Ianuzzi, Allyson; Pickar, Joel G; Khalsa, Partap S

2009-01-01

Quadruped animal models have been validated and used as biomechanical models for the lumbar spine. The biomechanics of the cat lumbar spine has not been well characterized, even though it is a common model used in neuromechanical studies. Compare the physiological ranges of motion and determine torque-limits for cat and human lumbar spine specimens during physiological motions. Biomechanics study. Cat and human lumbar spine specimens. Intervertebral angle (IVA), joint moment, yield point, torque-limit, and correlation coefficients. Cat (L2-sacrum) and human (T12-sacrum) lumbar spine specimens were mechanically tested to failure during displacement-controlled extension (E), lateral bending (LB), and axial rotation (AR). Single trials consisted of 10 cycles (10mm/s or 5 degrees /s) to a target displacement where the magnitude of the target displacement was increased for subsequent trials until failure occurred. Whole-lumbar stiffness, torque at yield point, and joint stiffness were determined. Scaling relationships were established using equations analogous to those that describe the load response of elliptically shaped beams. IVA magnitudes for cat and human lumbar spines were similar during physiological motions. Human whole-lumbar and joint stiffness magnitudes were significantly greater than those for cat spine specimens (p<.05). Torque-limits were also greater for humans compared with cats. Scaling relationships with high correlation (R(2) greater than 0.77) were established during later LB and AR. The current study defined "physiological ranges of movement" for human and cat lumbar spine specimens during displacement-controlled testing, and should be observed in future biomechanical studies conducted under displacement control.

Gait kinematics and kinetics are affected more by peripheral arterial disease than age

PubMed Central

Myers, Sara A.; Applequist, Bryon C.; Huisinga, Jessie M.; Pipinos, Iraklis I.; Johanning, Jason M.

2016-01-01

Peripheral arterial disease (PAD) produces abnormal gait and disproportionately affects older individuals. The current study investigated PAD gait biomechanics in young and older subjects. Sixty-one (31 < 65 years, age: 57.4 ± 5.3 years and 30 ≥ 65 years; age: 72.2 ± 5.4 years) patients with PAD and 52 healthy age matched controls were included. Patients with PAD were tested during pain free walking and compared to matched healthy controls. Joint kinematics and kinetics (torques) were compared using a 2 × 2 ANOVA (Groups: PAD vs. Control, Age: Younger vs. Older). Patients with PAD had significantly increased ankle and decreased hip range of motion during the stance phase as well as decreased ankle dorsiflexor torque compared to controls. Gait changes in older individuals are largely constrained to time-distance parameters. Joint kinematics and kinetics are significantly altered in patients with PAD during pain free ambulation. Symptomatic PAD produces a consistent ambulatory deficit across ages definable by advanced biomechanical analysis. The most important finding of the current study is that gait, in the absence of PAD and other ambulatory comorbidities, does not decline significantly with age based on advanced biomechanical analysis. Therefore, previous studies must be examined in the context of potential PAD patients being present in the population and future ambulatory studies must include PAD as a confounding factor when assessing the gait function of elderly individuals. PMID:27149635

The effect of ankle bracing on lower extremity biomechanics during landing: A systematic review.

PubMed

Mason-Mackay, A R; Whatman, C; Reid, D

2016-07-01

To examine the evidence for effect of ankle bracing on lower-extremity landing biomechanics. Literature review. Systematic search of the literature on EBSCO health databases. Articles critiqued by two reviewers. Ten studies were identified which investigated the effect of ankle bracing on landing biomechanics. Overall results suggest that landing biomechanics are altered with some brace types but studies disagree as to the particular variables affected. There is evidence that ankle bracing may alter lower-extremity landing biomechanics in a manner which predisposes athletes to injury. The focus of studies on specific biomechanical variables rather than biomechanical patterns, analysis of pooled data means in the presence of differing landing styles between participants, variation in landing-tasks investigated in different studies, and lack of studies investigating goal-directed sport-specific landing tasks creates difficulty in interpreting results. These areas require further research. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

In vivo ocular biomechanical compliance in thyroid eye disease.

PubMed

Vellara, Hans R; Hart, Richard; Gokul, Akilesh; McGhee, Charles N J; Patel, Dipika V

2017-08-01

To compare the ocular biomechanical properties in patients with thyroid eye disease (TED) and healthy participants using a non-contact Scheimpflug-based tonometer (CorVis ST). All eyes were examined by slit lamp biomicroscopy, corneal tomography and the CorVis ST (CST). Patients with TED were examined by a fellowship trained oculoplastics specialist to determine status and assess severity. The outputs from CST and additionally derived parameters, including maximum orbital deformation (MOD), were compared between healthy participants and patients with TED using Student's t-test. Furthermore, a multiple linear regression analysis was used to control for various factors known to influence ocular biomechanical responses to an air pulse. This study included 20 patients with TED and compared them with a cohort of 152 healthy participants. The mean age of patients with TED was 46.7±19.0 years and the mean age of healthy participants was 35.9±13.8 years (p=0.03). There were no statistically significant differences in gender distributions between both groups (p>0.05). Several CST parameters were significantly different between groups (p<0.05). Of note, however, MOD was significantly lower in patients with TED (0.16±0.04 mm) compared with the healthy participants (0.25±0.05 mm, p<0.001). This dissimilarity remained even after controlling for the various cofactors. Receiver-operating characteristic analysis revealed an area under the curve of 0.91±0.04 (95% CI 0.84 to 0.98, p<0.001) for MOD. The in vivo ocular biomechanics as measured by the CST reflects a reduced orbital compliance. This method of ocular biomechanical assessment may aid in the categorisation of TED severity and assist in monitoring and/or diagnosing TED. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Biomechanical analysis of the effect of congruence, depth and radius on the stability ratio of a simplistic 'ball-and-socket' joint model.

PubMed

Ernstbrunner, L; Werthel, J-D; Hatta, T; Thoreson, A R; Resch, H; An, K-N; Moroder, P

2016-10-01

The bony shoulder stability ratio (BSSR) allows for quantification of the bony stabilisers in vivo. We aimed to biomechanically validate the BSSR, determine whether joint incongruence affects the stability ratio (SR) of a shoulder model, and determine the correct parameters (glenoid concavity versus humeral head radius) for calculation of the BSSR in vivo. Four polyethylene balls (radii: 19.1 mm to 38.1 mm) were used to mould four fitting sockets in four different depths (3.2 mm to 19.1mm). The SR was measured in biomechanical congruent and incongruent experimental series. The experimental SR of a congruent system was compared with the calculated SR based on the BSSR approach. Differences in SR between congruent and incongruent experimental conditions were quantified. Finally, the experimental SR was compared with either calculated SR based on the socket concavity or plastic ball radius. The experimental SR is comparable with the calculated SR (mean difference 10%, sd 8%; relative values). The experimental incongruence study observed almost no differences (2%, sd 2%). The calculated SR on the basis of the socket concavity radius is superior in predicting the experimental SR (mean difference 10%, sd 9%) compared with the calculated SR based on the plastic ball radius (mean difference 42%, sd 55%). The present biomechanical investigation confirmed the validity of the BSSR. Incongruence has no significant effect on the SR of a shoulder model. In the event of an incongruent system, the calculation of the BSSR on the basis of the glenoid concavity radius is recommended.Cite this article: L. Ernstbrunner, J-D. Werthel, T. Hatta, A. R. Thoreson, H. Resch, K-N. An, P. Moroder. Biomechanical analysis of the effect of congruence, depth and radius on the stability ratio of a simplistic 'ball-and-socket' joint model. Bone Joint Res 2016;5:453-460. DOI: 10.1302/2046-3758.510.BJR-2016-0078.R1. © 2016 Ernstbrunner et al.

Comparing Running Specific and Traditional Prostheses During Running: Assessing Performance and Risk

DTIC Science & Technology

2016-09-01

extremity amputation (ILEA) running is limited with respect to biomechanical performance and injury risks. ILEA are able to run with both running...TERMS Kinetics, biomechanics , amputation, prosthesis, transtibial 16. SECURITY CLASSIFICATION OF: U 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES...with lower extremity amputation (ILEA) running is limited with respect to biomechanical performance and injury risks. ILEA are able to run with both

Intraarticular arthrofibrosis of the knee alters patellofemoral contact biomechanics.

PubMed

Mikula, Jacob D; Slette, Erik L; Dahl, Kimi D; Montgomery, Scott R; Dornan, Grant J; O'Brien, Luke; Turnbull, Travis Lee; Hackett, Thomas R

2017-12-19

Arthrofibrosis in the suprapatellar pouch and anterior interval can develop after knee injury or surgery, resulting in anterior knee pain. These adhesions have not been biomechanically characterized. The biomechanical effects of adhesions in the suprapatellar pouch and anterior interval during simulated quadriceps muscle contraction from 0 to 90° of knee flexion were assessed. Adhesions of the suprapatellar pouch and anterior interval were hypothesized to alter the patellofemoral contact biomechanics and increase the patellofemoral contact force compared to no adhesions. Across all flexion angles, suprapatellar adhesions increased the patellofemoral contact force compared to no adhesions by a mean of 80 N. Similarly, anterior interval adhesions increased the contact force by a mean of 36 N. Combined suprapatellar and anterior interval adhesions increased the mean patellofemoral contact force by 120 N. Suprapatellar adhesions resulted in a proximally translated patella from 0 to 60°, and anterior interval adhesions resulted in a distally translated patella at all flexion angles other than 15° (p < 0.05). The most important finding in this study was that patellofemoral contact forces were significantly increased by simulated adhesions in the suprapatellar pouch and anterior interval. Anterior knee pain and osteoarthritis may result from an increase in patellofemoral contact force due to patellar and quadriceps tendon adhesions. For these patients, arthroscopic lysis of adhesions may be beneficial.

Biomechanical and Histopathologic Effects of Pulsed-Light Accelerated Epithelium-On/-Off Corneal Collagen Cross-Linking.

PubMed

Zhang, Xiaoyu; Sun, Ling; Shen, Yang; Tian, Mi; Zhao, Jing; Zhao, Yu; Li, Meiyan; Zhou, Xingtao

2017-07-01

This study aimed to compare the biomechanical and histopathologic effects of transepithelial and accelerated epithelium-off pulsed-light accelerated corneal collagen cross-linking (CXL). A total of 24 New Zealand rabbits were analyzed after sham operation (control) or transepithelial or epithelium-off operation (45 mW/cm for both). The transepithelial group was treated with pulsed-light ultraviolet A for 5 minutes 20 seconds, and the epithelium-off group was treated for 90 seconds. Biomechanical testing, including ultimate stress, Young modulus, and the physiological modulus, was analyzed. Histological changes were evaluated by light microscopy and transmission electron microscopy. The stress-strain curve was nonlinear in both accelerated transepithelial and epithelium-off CXL groups. The stress and elastic moduli were all significantly higher in both experimental groups compared with the control group (P < 0.05), whereas there were no significant differences between the 2 treatment groups (P > 0.05). Six months after the operation, hematoxylin and eosin staining and transmission electron microscopy showed that the subcutaneous collagen fibers were arranged in a regular pattern, and the fiber density was higher in the experimental groups. Both transepithelial and accelerated epithelium-off CXL produced biomechanical and histopathologic improvements, which were not significantly different between the 2 pulsed-light accelerated CXL treatments.

Gender differences in the restoration of knee joint biomechanics during gait after anterior cruciate ligament reconstruction.

PubMed

Asaeda, Makoto; Deie, Masataka; Fujita, Naoto; Kono, Yoshifumi; Terai, Chiaki; Kuwahara, Wataru; Watanabe, Hodaka; Kimura, Hiroaki; Adachi, Nobuo; Sunagawa, Toru; Ochi, Mitsuo

2017-03-01

The aim of our study was to evaluate the effects of gender on recovery of knee joint biomechanics over the stance phase of gait after reconstruction of the anterior cruciate ligament (ACL). Gait parameters and knee joint kinematics and kinetics were compared in 32 patients (16 male and 16 female) who underwent ACL reconstruction for a unilateral ACL deficiency, with comparison to an age-, height-, and weight-matched Control group. Knee flexion, adduction and tibial rotation angles were measured and knee extension and abduction moment was calculated by inverse dynamics methods. Females exhibited more tibial external rotation, in both the Control and ACL groups (P<0.05), which was not changed after ACL reconstruction. Prior to reconstruction, sagittal plane biomechanics were changed, in both males and females, compared to the Control groups (P<0.05). These abnormal sagittal plane mechanics were recovered at 12months, but not six months post-reconstruction. We identified gender-based differences in tibial rotation that influenced the kinematics and kinetics of the knee over the stance phase of gait, both pre-operatively and post-ACL reconstruction. Evaluation of biomechanical effects of ACL injury, before and after reconstruction, should be separately evaluated for females and males. Copyright © 2017 Elsevier B.V. All rights reserved.

From conventional sensors to fibre optic sensors for strain and force measurements in biomechanics applications: a review.

PubMed

Roriz, Paulo; Carvalho, Lídia; Frazão, Orlando; Santos, José Luís; Simões, José António

2014-04-11

In vivo measurement, not only in animals but also in humans, is a demanding task and is the ultimate goal in experimental biomechanics. For that purpose, measurements in vivo must be performed, under physiological conditions, to obtain a database and contribute for the development of analytical models, used to describe human biomechanics. The knowledge and control of the mechanisms involved in biomechanics will allow the optimization of the performance in different topics like in clinical procedures and rehabilitation, medical devices and sports, among others. Strain gages were first applied to bone in a live animal in 40's and in 80's for the first time were applied fibre optic sensors to perform in vivo measurements of Achilles tendon forces in man. Fibre optic sensors proven to have advantages compare to conventional sensors and a great potential for biomechanical and biomedical applications. Compared to them, they are smaller, easier to implement, minimally invasive, with lower risk of infection, highly accurate, well correlated, inexpensive and multiplexable. The aim of this review article is to give an overview about the evolution of the experimental techniques applied in biomechanics, from conventional to fibre optic sensors. In the next sections the most relevant contributions of these sensors, for strain and force in biomechanical applications, will be presented. Emphasis was given to report of in vivo experiments and clinical applications. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biomechanical differences between unilateral and bilateral landings from a jump: gender differences.

PubMed

Pappas, Evangelos; Hagins, Marshall; Sheikhzadeh, Ali; Nordin, Margareta; Rose, Donald

2007-07-01

To determine the effect of landing type (unilateral vs. bilateral) and gender on the biomechanics of drop landings in recreational athletes. This study used a repeated measures design to compare bilateral and unilateral landings in male and female athletes. A repeated measures multivariate analysis of variance (type of landing*gender) was performed on select variables. Biomechanics laboratory. Sixteen female and 16 male recreational athletes. Kinetic, kinematic, and electromyographic (EMG) data were collected on participants while performing bilateral and unilateral landings from a 40-cm platform. Compared to bilateral landings, subjects performed unilateral landings with increased knee valgus, decreased knee flexion at initial contact, decreased peak knee flexion, decreased relative hip adduction, and increased normalized EMG of the rectus femoris, medial hamstrings, lateral hamstrings, and medial gastrocnemius (P < 0.005). During both types of landing, females landed with increased knee valgus and normalized vertical ground reaction force (VGRF) compared to males (P < 0.009), however, the interaction of landing type*gender was not significant (P = 0.29). Compared to bilateral landings, male and female recreational athletes performed unilateral landings with significant differences in knee kinematic and EMG variables. Female athletes landed with increased knee valgus and VGRF compared to males during both types of landing.

The role of isolated posterior cruciate ligament reconstruction in knees with combined posterior cruciate ligament and posterolateral complex injury.

PubMed

Lee, Dong-Yeong; Park, Young-Jin; Kim, Dong-Hee; Kim, Hyun-Jung; Nam, Dae-Cheol; Park, Jin-Sung; Hwang, Sun-Chul

2017-08-14

This is a meta-analysis comparing biomechanical outcomes to determine whether an isolated posterior cruciate ligament (PCL) reconstruction can restore normal knee kinematics in a combined PCL/posterolateral complex (PLC) injury and whether double-bundle (DB) PCL reconstruction is superior in controlling posterior and rotational laxity compared with single-bundle (SB) PCL reconstruction in a PCL/PLC-deficient knee. A number of electronic databases were searched for relevant articles published through August 2016 that compared biomechanical outcomes of PCL reconstruction in patients who underwent reconstruction for combined PCL/PLC deficiencies. Data were searched, extracted, analysed, and assessed for quality according to Cochrane Collaboration guidelines, and biomechanical outcomes were evaluated using various outcome values. The results are presented as relative ratios for binary outcomes and standard mean differences for continuous outcomes with 95% confidence intervals. Five biomechanical studies were included in this meta-analysis. There were significant differences in laxities such as posterior tibial translation (PTT), external rotation, varus rotation, and PTT coupled with external rotation in the isolated PCL reconstruction group compared with the native PCL group. Furthermore, there were no significant differences in laxities such as PTT, external rotation, or varus rotation between the SB and DB PCL reconstruction groups. Isolated PCL reconstruction, whether SB or DB, could not restore normal knee kinematics in the PCL/PLC-deficient knee. In such cases, residual laxity after isolated PCL reconstruction can be controlled successfully with PLC reconstruction. Therefore, simultaneous PCL and PLC reconstruction is recommended for patients with combined PCL/PLC injury.

The comparative biomechanics of the reinforced interdental crossover and the Stout loop composite splints for mandibular fracture repair in dogs.

PubMed

Kitshoff, A M; de Rooster, H; Ferreira, S M; Burger, D; Steenkamp, G

2013-01-01

To describe a new technique, the reinforced interdental crossover composite splint (RIC), for transverse mandibular fracture repair in dogs. This technique was compared biomechanically with the established reinforced interdental Stout loop composite splint (RIS) technique. Six pairs of mandibles from young adult small breed dogs were used for the study. Osteotomies were created in a standardized fashion and fixed with either RIC or RIS. All composite splint constructs were tested biomechanically with a cantilever bending force, using a single column testing machine at a rate of 2 mm/min. The time of application, amount of composite used, ultimate force, stiffness, total displacement, and total energy absorbed during displacement of the rostral mandibular segment were calculated and compared between the two groups. No significant difference was found when comparing the time of application of the RIC and the RIS techniques. All implants failed by either composite resin fracture over the region of the osteotomy or by fracture between the first and second molar followed by detachment of the resin from the lingual enamel surface of the first molar. Differences between the RIC and RIS in force (80.5 N ± 40.3 and 51.8 N ± 27.4. respectively) and stiffness (16.2 N/mm ± 4.4 and 10.1 N/mm ± 4.1 respectively) were significant (p = 0.03). However differences between the two techniques in displacement and total energy absorbed were not significant. In experimentally fractured mandibles of young adult dogs there is evidence that RIC is biomechanically similar to RIS.

ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION USING THE DOUBLE-BUNDLE TECHNIQUE - EVALUATION IN THE BIOMECHANICS LABORATORY.

PubMed

D'Elia, Caio Oliveira; Bitar, Alexandre Carneiro; Castropil, Wagner; Garofo, Antônio Guilherme Padovani; Cantuária, Anita Lopes; Orselli, Maria Isabel Veras; Luques, Isabela Ugo; Duarte, Marcos

2011-01-01

The objective of this study was to describe the methodology of knee rotation analysis using biomechanics laboratory instruments and to present the preliminary results from a comparative study on patients who underwent anterior cruciate ligament (ACL) reconstruction using the double-bundle technique. The protocol currently used in our laboratory was described. Three-dimensional kinematic analysis was performed and knee rotation amplitude was measured on eight normal patients (control group) and 12 patients who were operated using the double-bundle technique, by means of three tasks in the biomechanics laboratory. No significant differences between operated and non-operated sides were shown in relation to the mean amplitudes of gait, gait with change in direction or gait with change in direction when going down stairs (p > 0.13). The preliminary results did not show any difference in the double-bundle ACL reconstruction technique in relation to the contralateral side and the control group.

Ocular biomechanical measurements on post-keratoplasty corneas using a Scheimpflug-based noncontact device

PubMed Central

Modis, Laszlo; Hassan, Ziad; Szalai, Eszter; Flaskó, Zsuzsanna; Berta, Andras; Nemeth, Gabor

2016-01-01

AIM To analyse ocular biomechanical properties, central corneal thickness (CCT) and intraocular pressure (IOP) in post-keratoplasty eyes, as compared to normal subjects, with a new Scheimpflug-based technology. Moreover, biomechanical data were correlated with the size and age of the donor and recipient corneas. METHODS Measurements were conducted on 46 eyes of 46 healthy patients without any corneal pathology (age: 53.83±20.8y) and 30 eyes of 28 patients after penetrating keratoplasty (age: 49.43±21.34y). Ten biomechanical parameters, the CCT and IOP were recorded by corneal visualization scheimpflug technology (CorVis ST) using high-speed Scheimpflug imaging. Keratometry values were also recorded using Pentacam HR system. Scheimpflug measurements were performed after 43.41±40.17mo (range: 11-128mo) after the keratoplasty and after 7.64±2.34mo (range: 5-14mo) of suture removal. RESULTS Regarding the device-specific biomechanical parameters, the highest concavity time and radius values showed a significant decrease between these two groups (P=0.01 and P<0.001). None of other biomechanical parameters disclosed a significant difference. The CCT showed a significant difference between post-keratoplasty eyes as compared to normal subjects (P=0.003) using the CorVis ST device. The IOP was within the normal range in both groups (P=0.84). There were no significant relationships between the keratometric data, the size of the donor and recipient, age of the donor and recipient and biomechanical properties obtained by CorVis ST. CONCLUSION The ocular biomechanics remain stable after penetrating keratoplasty according to the CorVis ST measurements. Only two from the ten device-specific parameters have importance in the follow-up period after penetrating keratoplasty. PMID:26949641

Tape Versus Suture in Arthroscopic Rotator Cuff Repair: Biomechanical Analysis and Assessment of Failure Rates at 6 Months

PubMed Central

Liu, Rui Wen; Lam, Patrick Hong; Shepherd, Henry M.; Murrell, George A. C.

2017-01-01

Background: Rotator cuff retears after surgical repair are associated with poorer subjective and objectives clinical outcomes than intact repairs. Purpose: The aims of this study were to (1) examine the biomechanical differences between rotator cuff repair using No. 2 suture and tape in an ovine model and (2) compare early clinical outcomes between patients who had rotator cuff repair with tape and patients who had repair with No. 2 suture. Study Design: Controlled laboratory study and cohort study; Level of evidence, 3. Methods: Biomechanical testing of footprint contact pressure and load to failure were conducted with 16 ovine shoulders using a tension band repair technique with 2 different types of sutures (No. 2 suture [FiberWire; Arthrex] and tape [FiberTape; Arthrex]) with the same knotless anchor system. A retrospective study of 150 consecutive patients (tape, n = 50; suture, n = 100) who underwent arthroscopic rotator cuff repair by a single surgeon with tear size larger than 1.5 × 1 cm was conducted. Ultrasound was used to evaluate the repair integrity at 6 months postsurgery. Results: Rotator cuff repair using tape had greater footprint contact pressure (mean ± standard error of the mean, 0.33 ± 0.03 vs 0.11 ± 0.3 MPa; P < .0001) compared with repair using No. 2 sutures at 0° abduction with a 30-N load applied across the repaired tendon. The ultimate failure load of the tape repair was greater than that for suture repair (217 ± 28 vs 144 ± 14 N; P < .05). The retear rate was similar between the tape (16%; 8/50) and suture groups (17%; 17/100). Conclusion: Rotator cuff repair with the wider tape compared with No. 2 suture did not affect the retear rate at 6 months postsurgery, despite having superior biomechanical properties. PMID:28451619

Comparative anatomy and biomechanical properties of atlantoaxial ligaments in equine, bovine, and canine cadaveric specimens.

PubMed

Forterre, Franck; Stoffel, Michael H; Koch, Christoph; Precht, Christina; Waschk, Maja; Bürki, Alexander

2017-05-22

Atlantoaxial instability has been reported in humans, dogs, equids and ruminants. The functional role of the atlantoaxial ligaments has only been described rudimentarily in equids and ruminants. The goal of the present cadaveric study was to compare the anatomy between the different species and to comparatively assess the role of the stabilizing ligaments of the atlantoaxial joint under sagittal shear loading in canine, equine, and bovine cervical spines. Three equine, bovine, and canine cadaveric specimens were investigated. Biomechanical testing was performed using a purpose built shear-testing device driven by a uniaxial servo-hydraulic testing machine. Three cycles in a dorsoventral direction with a constant quasi-static velocity of 0.2 mm/s up to a limiting force of 50 N (canine) or 250 N (bovine, equine), respectively, were performed for each specimen tested. Load and linear displacement were measured by the displacement sensor and load cell of the testing system at a sampling rate of 20 Hz. Tests were performed and the range of motion determined with both intact and transected atlantoaxial ligaments. The range of motion was significantly increased after transection of the ligaments only in the canine specimens. The bovine atlantoaxial joint was biomechanically more stable than in equids. Species-specific anatomical and biomechanical differences of the atlantoaxial ligaments in canines, equids, and bovines were detected. The significance of these differences and their impact on the pathogenesis of atlantoaxial subluxations and subsequent treatment remain open questions.

Finite Element Analysis of Influence of Axial Position of Center of Rotation of a Cervical Total Disc Replacement on Biomechanical Parameters: Simulated 2-Level Replacement Based on a Validated Model.

PubMed

Li, Yang; Zhang, Zhenjun; Liao, Zhenhua; Mo, Zhongjun; Liu, Weiqiang

2017-10-01

Finite element models have been widely used to predict biomechanical parameters of the cervical spine. Previous studies investigated the influence of position of rotational centers of prostheses on cervical biomechanical parameters after 1-level total disc replacement. The purpose of this study was to explore the effects of axial position of rotational centers of prostheses on cervical biomechanics after 2-level total disc replacement. A validated finite element model of C3-C7 segments and 2 prostheses, including the rotational center located at the superior endplate (SE) and inferior endplate (IE), was developed. Four total disc replacement models were used: 1) IE inserted at C4-C5 disc space and IE inserted at C5-C6 disc space (IE-IE), 2) IE-SE, 3) SE-IE, and 4) SE-SE. All models were subjected to displacement control combined with a 50 N follower load to simulate flexion and extension motions in the sagittal plane. For each case, biomechanical parameters, including predicted moments, range of rotation at each level, facet joint stress, and von Mises stress on the ultra-high-molecular-weight polyethylene core of the prostheses, were calculated. The SE-IE model resulted in significantly lower stress at the cartilage level during extension and at the ultra-high-molecular-weight polyethylene cores when compared with the SE-SE construct and did not generate hypermotion at the C4-C5 level compared with the IE-SE and IE-IE constructs. Based on the present analysis, the SE-IE construct is recommended for treating cervical disease at the C4-C6 level. This study may provide a useful model to inform clinical operations. Copyright © 2017 Elsevier Inc. All rights reserved.

Role of Aquaporin 0 in lens biomechanics

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

Sindhu Kumari, S.; Gupta, Neha; Shiels, Alan

Maintenance of proper biomechanics of the eye lens is important for its structural integrity and for the process of accommodation to focus near and far objects. Several studies have shown that specialized cytoskeletal systems such as the beaded filament (BF) and spectrin-actin networks contribute to mammalian lens biomechanics; mutations or deletion in these proteins alters lens biomechanics. Aquaporin 0 (AQP0), which constitutes ∼45% of the total membrane proteins of lens fiber cells, has been shown to function as a water channel and a structural cell-to-cell adhesion (CTCA) protein. Our recent ex vivo study on AQP0 knockout (AQP0 KO) mouse lenses showedmore » the CTCA function of AQP0 could be crucial for establishing the refractive index gradient. However, biomechanical studies on the role of AQP0 are lacking. The present investigation used wild type (WT), AQP5 KO (AQP5{sup −/−}), AQP0 KO (heterozygous KO: AQP0{sup +/−}; homozygous KO: AQP0{sup −/−}; all in C57BL/6J) and WT-FVB/N mouse lenses to learn more about the role of fiber cell AQPs in lens biomechanics. Electron microscopic images exhibited decreases in lens fiber cell compaction and increases in extracellular space due to deletion of even one allele of AQP0. Biomechanical assay revealed that loss of one or both alleles of AQP0 caused a significant reduction in the compressive load-bearing capacity of the lenses compared to WT lenses. Conversely, loss of AQP5 did not alter the lens load-bearing ability. Compressive load-bearing at the suture area of AQP0{sup +/−} lenses showed easy separation while WT lens suture remained intact. These data from KO mouse lenses in conjunction with previous studies on lens-specific BF proteins (CP49 and filensin) suggest that AQP0 and BF proteins could act co-operatively in establishing normal lens biomechanics. We hypothesize that AQP0, with its prolific expression at the fiber cell membrane, could provide anchorage for cytoskeletal structures like BFs and together they help to confer fiber cell shape, architecture and integrity. To our knowledge, this is the first report identifying the involvement of an aquaporin in lens biomechanics. Since accommodation is required in human lenses for proper focusing, alteration in the adhesion and/or water channel functions of AQP0 could contribute to presbyopia. - Highlights: • AQP0 aids in lens biomechanics. • AQP0 provides lens stiffness. • AQP0 is critical for lens transparency. • AQP0 could play a significant role in lens accommodation in human. • Alteration in the function(s) of lens AQP0 could lead to presbyopia.« less

The effect of a daily quiz (TOPday) on self-confidence, enthusiasm, and test results for biomechanics.

PubMed

Tanck, Esther; Maessen, Martijn F H; Hannink, Gerjon; van Kuppeveld, Sascha M H F; Bolhuis, Sanneke; Kooloos, Jan G M

2014-01-01

Many students in Biomedical Sciences have difficulty understanding biomechanics. In a second-year course, biomechanics is taught in the first week and examined at the end of the fourth week. Knowledge is retained longer if the subject material is repeated. However, how does one encourage students to repeat the subject matter? For this study, we developed 'two opportunities to practice per day (TOPday)', consisting of multiple-choice questions on biomechanics with immediate feedback, which were sent via e-mail. We investigated the effect of TOPday on self-confidence, enthusiasm, and test results for biomechanics. All second-year students (n = 95) received a TOPday of biomechanics on every regular course day with increasing difficulty during the course. At the end of the course, a non-anonymous questionnaire was conducted. The students were asked how many TOPday questions they completed (0-6 questions [group A]; 7-18 questions [group B]; 19-24 questions [group C]). Other questions included the appreciation for TOPday, and increase (no/yes) in self-confidence and enthusiasm for biomechanics. Seventy-eight students participated in the examination and completed the questionnaire. The appreciation for TOPday in group A (n = 14), B (n = 23) and C (n = 41) was 7.0 (95 % CI 6.5-7.5), 7.4 (95 % CI 7.0-7.8), and 7.9 (95 % CI 7.6-8.1), respectively (p < 0.01 between A and C). Of the students who actively participated (B and C), 91 and 80 % reported an increase in their self-confidence and enthusiasm, respectively, for biomechanics due to TOPday. In addition, they had a higher test result for biomechanics (p < 0.01) compared with those who did not actively participate (A). In conclusion, the teaching method 'TOPday' seems an effective way to encourage students to repeat the subject material, with the extra advantage that students are stimulated to keep on practising for the examination. The appreciation was high and there was a positive association between active participation, on the one hand, and self-confidence, enthusiasm, and test results for biomechanics on the other.

Biomechanical interpretation of a free-breathing lung motion model

NASA Astrophysics Data System (ADS)

Zhao, Tianyu; White, Benjamin; Moore, Kevin L.; Lamb, James; Yang, Deshan; Lu, Wei; Mutic, Sasa; Low, Daniel A.

2011-12-01

The purpose of this paper is to develop a biomechanical model for free-breathing motion and compare it to a published heuristic five-dimensional (5D) free-breathing lung motion model. An ab initio biomechanical model was developed to describe the motion of lung tissue during free breathing by analyzing the stress-strain relationship inside lung tissue. The first-order approximation of the biomechanical model was equivalent to a heuristic 5D free-breathing lung motion model proposed by Low et al in 2005 (Int. J. Radiat. Oncol. Biol. Phys. 63 921-9), in which the motion was broken down to a linear expansion component and a hysteresis component. To test the biomechanical model, parameters that characterize expansion, hysteresis and angles between the two motion components were reported independently and compared between two models. The biomechanical model agreed well with the heuristic model within 5.5% in the left lungs and 1.5% in the right lungs for patients without lung cancer. The biomechanical model predicted that a histogram of angles between the two motion components should have two peaks at 39.8° and 140.2° in the left lungs and 37.1° and 142.9° in the right lungs. The data from the 5D model verified the existence of those peaks at 41.2° and 148.2° in the left lungs and 40.1° and 140° in the right lungs for patients without lung cancer. Similar results were also observed for the patients with lung cancer, but with greater discrepancies. The maximum-likelihood estimation of hysteresis magnitude was reported to be 2.6 mm for the lung cancer patients. The first-order approximation of the biomechanical model fit the heuristic 5D model very well. The biomechanical model provided new insights into breathing motion with specific focus on motion trajectory hysteresis.

Control conditions for footwear insole and orthotic research.

PubMed

Lewinson, Ryan T; Worobets, Jay T; Stefanyshyn, Darren J

2016-07-01

Footwear insoles/orthotics alter variables associated with musculoskeletal injury; however, their clinical effectiveness is inconclusive. One explanation for this is the possibility that control conditions may actually produce biomechanical changes that induce clinical responses. The purpose of this study was to compare insole/orthotic control conditions to identify if variables at the ground, ankle and knee that are associated with injury are altered relative to what participants would normally experience in their own shoes. Gait analysis was performed on 15 participants during walking and running while wearing (1) their own shoes, (2) #1 with a 3mm flat insole, (3) a standardized shoe, and (4) #3 with a 3mm flat insole, where external knee adduction moments, external knee adduction angular impulses, internal ankle inversion moments, and vertical ground reaction force loading rates were determined. Conditions 2-4 were expressed as percent changes relative to condition 1, and tests of proportions assessed if there were a significant number of individuals experiencing a biomechanically relevant change for each variable. Repeated-measures ANOVAs were used to identify group differences between conditions. The majority of movement-footwear-variable combinations contained a proportion of individuals experiencing biomechanically relevant changes compared to condition 1 that was significantly greater than the expected proportion of 20%. No systematic differences were found between conditions. This suggests that conditions 2-4 may alter biomechanics relative to baseline for many participants, but not in a consistent way across participants. It is recommended that participant's own footwear be used as control conditions in future trials where biomechanics are primary variables of interest. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of transtibial amputee and non-amputee biomechanics during a common turning task.

PubMed

Segal, Ava D; Orendurff, Michael S; Czerniecki, Joseph M; Schoen, Jason; Klute, Glenn K

2011-01-01

The biomechanics of amputee turning gait has been minimally studied, in spite of its integral relationship with the more complex gait required for household or community ambulation. This study compares the biomechanics of unilateral transtibial amputees and non-amputees completing a common turning task. Full body gait analysis was completed for subjects walking at comparable self-selected speeds around a 1m radius circular path. Peak internal and external rotation moments of the hip, knee and ankle, mediolateral ground reaction impulse (ML GRI), peak effective limb length, and stride length were compared across conditions (non-amputee, amputee prosthetic limb, amputee sound limb). Amputees showed decreased internal rotation moments at the prosthetic limb hip and knee compared to non-amputees, perhaps as a protective mechanism to minimize stress on the residual limb. There was also an increase in amputee sound limb hip external rotation moment in early stance compared to non-amputees, which may be a compensation for the decrease in prosthetic limb internal rotation moment during late stance of the prior step. ML GRI was decreased for the amputee inside limb compared to non-amputee, possibly to minimize the body's acceleration in the direction of the turn. Amputees also exhibited a shorter inside limb stride length compared to non-amputees. Both decreased ML GRI and stride length indicate a COM that is more centered over the base of support, which may minimize the risk of falling. Finally, a longer effective limb length was found for the amputee inside limb turning, possibly due to excessive trunk shift. Published by Elsevier B.V.

Combining epidemiology and biomechanics in sports injury prevention research: a new approach for selecting suitable controls.

PubMed

Finch, Caroline F; Ullah, Shahid; McIntosh, Andrew S

2011-01-01

Several important methodological issues need to be considered when designing sports injury case-control studies. Major design goals for case-control studies include the accounting for prior injury risk exposure, and optimal definitions of both cases and suitable controls are needed to ensure this. This article reviews methodological aspects of published sports injury case-control studies, particularly with regard to the selection of controls. It argues for a new approach towards selecting controls for case-control studies that draws on an interface between epidemiological and biomechanical concepts. A review was conducted to identify sport injury case-control studies published in the peer-review literature during 1985-2008. Overall, 32 articles were identified, of which the majority related to upper or lower extremity injuries. Matching considerations were used for control selection in 16 studies. Specific mention of application of biomechanical principles in the selection of appropriate controls was absent from all studies, including those purporting to evaluate the benefits of personal protective equipment to protect against impact injury. This is a problem because it could lead to biased conclusions, as cases and controls are not fully comparable in terms of similar biomechanical impact profiles relating to the injury incident, such as site of the impact on the body. The strength of the conclusions drawn from case-control studies, and the extent to which results can be generalized, is directly influenced by the definition and recruitment of cases and appropriate controls. Future studies should consider the interface between epidemiological and biomechanical concepts when choosing appropriate controls to ensure that proper adjustment of prior exposure to injury risk is made. To provide necessary guidance for the optimal selection of controls in case-control studies of interventions to prevent sports-related impact injury, this review outlines a new case-control selection strategy that reflects the importance of biomechanical considerations, which ensures that controls are selected based on the presence of the same global injury mechanism as the cases. To summarize, the general biomechanical principles that should apply to the selection of controls in future case-control studies are as follows: (i) each control must have been exposed to the same global injury mechanism as the case, (e.g. head impact, fall onto outstretched arm); and (ii) intrinsic (individual) factors (e.g. age, sex, skill level) that might modify the person's response to the relevant biomechanical loads are adjusted when either selecting the controls or are in the analysis phase. The same considerations for control selection apply to other study designs such as matched cohort studies or case-crossover studies.

Confidence crisis of results in biomechanics research.

PubMed

Knudson, Duane

2017-11-01

Many biomechanics studies have small sample sizes and incorrect statistical analyses, so reporting of inaccurate inferences and inflated magnitude of effects are common in the field. This review examines these issues in biomechanics research and summarises potential solutions from research in other fields to increase the confidence in the experimental effects reported in biomechanics. Authors, reviewers and editors of biomechanics research reports are encouraged to improve sample sizes and the resulting statistical power, improve reporting transparency, improve the rigour of statistical analyses used, and increase the acceptance of replication studies to improve the validity of inferences from data in biomechanics research. The application of sports biomechanics research results would also improve if a larger percentage of unbiased effects and their uncertainty were reported in the literature.

Gender differences in joint biomechanics during walking: normative study in young adults.

PubMed

Kerrigan, D C; Todd, M K; Della Croce, U

1998-01-01

The effect of gender on specific joint biomechanics during gait has been largely unexplored. Given the perceived, subjective, and temporal differences in walking between genders, we hypothesized that quantitative analysis would reveal specific gender differences in joint biomechanics as well. Sagittal kinematic (joint motion) and kinetic (joint torque and power) data from the lower limbs during walking were collected and analyzed in 99 young adult subjects (49 females), aged 20 to 40 years, using an optoelectronic motion analysis and force platform system. Kinetic data were normalized for both height and weight. Female and male data were compared graphically and statistically to assess differences in all major peak joint kinematic and kinetic values. Females had significantly greater hip flexion and less knee extension before initial contact, greater knee flexion moment in pre-swing, and greater peak mechanical joint power absorption at the knee in pre-swing (P < 0.0019 for each parameter). Other differences were noted (P < 0.05) that were not statistically significant when accounting for multiple comparisons. These gender differences may provide new insights into walking dynamics and may be important for both clinical and research studies in motivating the development of separate biomechanical reference databases for males and females.

Evaluation of lumbar segmental instability in degenerative diseases by using a new intraoperative measurement system.

PubMed

Hasegawa, Kazuhiro; Kitahara, Ko; Hara, Toshiaki; Takano, Ko; Shimoda, Haruka; Homma, Takao

2008-03-01

In vivo quantitative measurement of lumbar segmental stability has not been established. The authors developed a new measurement system to determine intraoperative lumbar stability. The objective of this study was to clarify the biomechanical properties of degenerative lumbar segments by using the new method. Twenty-two patients with a degenerative symptomatic segment were studied and their measurements compared with those obtained in normal or asymptomatic degenerative segments (Normal group). The measurement system produces cyclic flexion-extension through spinous process holders by using a computer-controlled motion generator with all ligamentous structures intact. The following biomechanical parameters were determined: stiffness, absorption energy (AE), and neutral zone (NZ). Discs with degeneration were divided into 2 groups based on magnetic resonance imaging grading: degeneration without collapse (Collapse[-]) and degeneration with collapse (Collapse[+]). Biomechanical parameters were compared among the groups. Relationships among the biomechanical parameters and age, diagnosis, or radiographic parameters were analyzed. The mean stiffness value in the Normal group was significantly greater than that in Collapse(-) or Collapse(+) group. There was no significant difference in the average AE value among the Normal, Collapse(-), and Collapse(+) groups. The NZ in the Collapse(-) was significantly higher than in the Normal or Collapse(+) groups. Stiffness was negatively and NZ was positively correlated with age. Stiffness demonstrated a significant negative and NZ a significant positive relationship with disc height, however. There were no significant differences in stiffness between spines in the Collapse(-) and Collapse(+) groups. The values of a more sensitive parameter, NZ, were higher in Collapse(-) than in Collapse(+) groups, demonstrating that degenerative segments with preserved disc height have a latent instability compared to segments with collapsed discs.

Biomechanical Properties of the Skin in Patients with Breast Cancer-Related Lymphedema Compared to Healthy Individuals.

PubMed

Killaars, R C; Penha, T R Lopez; Heuts, E M; van der Hulst, R R J W; Piatkowski, A A

2015-09-01

Biomechanical skin changes in breast cancer-related lymphedema (BRCL) have barely been described and objectively tested. This study aims to compare the skin of upper limb lymphedema with skin of the healthy contralateral arm, in order to demonstrate changes of elasticity, viscoelasticity, and level of hydration of the skin in BCRL. The secondary aim is to investigate the correlation between biomechanical skin changes and measurements that are currently used in clinical practice, such as volume measurement and lymph-ICF score. Eighteen patients with BCRL and 18 healthy individuals were included in the study. A Cutometer® was used for measurements for skin elasticity and viscoelasticity on both arms of each subject. A Corneometer® was used for measurements of skin hydration. Measurements of both test groups were compared. In BCRL patients, there was a significant difference (p = < 0.028) between the elasticity of the skin of the lymphedema arm compared to the healthy contralateral arm. There were no significant differences for level of skin hydration or viscoelasticity in lymphedema patients between the measurements on the skin of the lymphedematous and healthy arm. In healthy individuals, there were no significant differences for all measurements between skin of both arms. Spearman's correlation was significant (p = < 0.01) for difference in volume and difference in elasticity in BCRL patients. This study shows an impaired elasticity for the skin of the lower arm in patients with lymphedema compared to the contralateral healthy arm. Promising evidence is suggested for the use of the Cutometer device in the diagnostic evaluation of BCRL.

[Retention and biomechanics of retentive complexes. 3. The Kratochvil school and current retentive complexes].

PubMed

Enrique Fernández, M; Jacques Grimonster, L

1989-04-01

The authors analyse the biomechanical bases of the Kratochvil "retentive complex" and show how they have induced the nowadays north-american propositions (RPI & RPA). They compare them to the european ones (Nally-Martinet).

[RESEARCH PROGRESS OF BIOMECHANICS OF PROXIMAL ROW CARPAL INSTABILITY].

PubMed

Guo, Jinhai; Huang, Fuguo

2015-01-01

To review the research progress of the biomechanics of proximal row carpal instability (IPRC). The related literature concerning IPRC was extensively reviewed. The biomechanical mechanism of the surrounding soft tissue in maintaining the stability of the proximal row carpal (PRC) was analyzed, and the methods to repair or reconstruct the stability and function of the PRC were summarized from two aspects including basic biomechanics and clinical biomechanics. The muscles and ligaments of the PRC are critical to its stability. Most scholars have reached a consensus about biomechanical mechanism of the PRC, but there are still controversial conclusions on the biomechanics mechanism of the surrounding soft tissue to stability of distal radioulnar joint when the triangular fibrocartilage complex are damaged and the biomechanics mechanism of the scapholunate ligament. At present, there is no unified standard about the methods to repair or reconstruct the stability and function of the PRC. So, it is difficult for clinical practice. Some strides have been made in the basic biomechanical study on muscle and ligament and clinical biomechanical study on the methods to repair or reconstruct the stability and function of PRC, but it will be needed to further study the morphology of carpal articular surface and the adjacent articular surface, the pressure of distal carpals to proximal carpal and so on.

Structure-function relationships of human meniscus.

PubMed

Danso, Elvis K; Oinas, Joonas M T; Saarakkala, Simo; Mikkonen, Santtu; Töyräs, Juha; Korhonen, Rami K

2017-03-01

Biomechanical properties of human meniscus have been shown to be site-specific. However, it is not known which meniscus constituents at different depths and locations contribute to biomechanical properties obtained from indentation testing. Therefore, we investigated the composition and structure of human meniscus in a site- and depth-dependent manner and their relationships with tissue site-specific biomechanical properties. Elastic and poroelastic properties were analyzed from experimental stress-relaxation and sinusoidal indentation measurements with fibril reinforced poroelastic finite element modeling. Proteoglycan (PG) and collagen contents, as well as the collagen orientation angle, were determined as a function of tissue depth using microscopic and spectroscopic methods, and they were compared with biomechanical properties. For all the measurement sites (anterior, middle and posterior) of lateral and medial menisci (n=26), PG content and collagen orientation angle increased as a function of tissue depth while the collagen content had an initial sharp increase followed by a decrease across tissue depth. The highest values (p<0.05) of elastic parameters (equilibrium and instantaneous moduli) and strain-dependent biomechanical parameters (strain-dependent fibril network modulus and permeability) were observed in the anterior horn of the medial meniscus. This location had also higher (p<0.05) PG content in the deep meniscus, higher (p<0.05) collagen content in the entire tissue depth, and lower (p<0.05) collagen orientation angle at the superficial tissue, as compared to many other locations. On the other hand, in certain comparisons (such as anterior vs. middle sites of the medial meniscus) significantly higher (p<0.05) collagen content and lower orientation angle, without any difference in the PG content, were consistent with increased meniscus modulus and/or nonlinear permeability. This study suggests that nonlinear biomechanical properties of meniscus, caused by the collagen network and fluid, may be strongly influenced by tissue osmotic swelling from the deep meniscus caused by the increased PG content, leading to increased collagen fibril tension. These nonlinear biomechanical properties are suggested to be further amplified by higher collagen content at all tissue depths and superficial collagen fibril orientation. However, these structure-function relationships are suggested to be highly site-specific. Copyright © 2016 Elsevier Ltd. All rights reserved.

The association of external knee adduction moment with biomechanical variables in osteoarthritis: a systematic review.

PubMed

Foroughi, Nasim; Smith, Richard; Vanwanseele, Benedicte

2009-10-01

Osteoarthritis (OA) is a musculoskeletal disorder primarily affecting the older population and resulting in chronic pain and disability. Biomechanical variables, associated with OA severity such as external knee adduction moment (KAM) and joint malalignment, may affect the disease process by altering the bone-on-bone forces during gait. To investigate the association between biomechanical variables and KAM in knee OA. A systematic search for published studies' titles and abstracts was performed on Ovid Medline, Cumulative index to Nursing and Allied Health, PREMEDLINE, EBM reviews and SPORTDiscus. Fourteen studies met the inclusion criteria and were considered for the review. The magnitude and time course of KAM during gait appeared to be consistent across laboratories and computational methods. Only two of the included studies that compared patients with OA to a control group reported a higher peak KAM for the OA group. Knee adduction moment increased with OA severity and was directly proportional to varus malalignment. Classifying the patients on the basis of disease severity decreased the group variability, permitting the differences to be more detectable. Biomechanical variables such as varus malalignment are associated with KAM and therefore may affect the disease process. These variables should be taken into considerations when developing therapeutic interventions for individuals suffering from knee OA.

Improved knee biomechanics among patients reporting a good outcome in knee-related quality of life one year after total knee arthroplasty.

PubMed

Naili, Josefine E; Wretenberg, Per; Lindgren, Viktor; Iversen, Maura D; Hedström, Margareta; Broström, Eva W

2017-03-21

It is not well understood why one in five patients report poor outcomes following knee arthroplasty. This study evaluated changes in knee biomechanics, and perceived pain among patients reporting either a good or a poor outcome in knee-related quality of life after total knee arthroplasty. Twenty-eight patients (mean age 66 (SD 7) years) were included in this prospective study. Within one month of knee arthroplasty and one year after surgery, patients underwent three-dimensional (3D) gait analysis, completed the Knee Injury and Osteoarthritis Outcome Score (KOOS), and rated perceived pain using a visual analogue scale. A "good outcome" was defined as a change greater than the minimally detectable change in the KOOS knee-related quality of life, and a "poor outcome" was defined as change below the minimally detectable change. Nineteen patients (68%) were classified as having a good outcome. Groups were analyzed separately and knee biomechanics were compared using a two-way repeated measures ANOVA. Differences in pain between groups were evaluated using Mann Whitney U test. Patients classified as having a good outcome improved significantly in most knee gait biomechanical outcomes including increased knee flexion-extension range, reduced peak varus angle, increased peak flexion moment, and reduced peak valgus moment. The good outcome group also displayed a significant increase in walking speed, a reduction (normalization) of stance phase duration (% of gait cycle) and increased passive knee extension. Whereas, the only change in knee biomechanics, one year after surgery, for patients classified as having a poor outcome was a significant reduction in peak varus angle. No differences in pain postoperatively were found between groups. Patients reporting a good outcome in knee-related quality of life improved in knee biomechanics during gait, while patients reporting a poor outcome, despite similar reduction in pain, remained unchanged in knee biomechanics one year after total knee arthroplasty. With regards to surgeon-controlled biomechanical factors, surgery may most successfully address frontal plane knee alignment. However, achieving a good outcome in patient-reported knee-related quality of life may be related to dynamic improvements in the sagittal plane.

[Structural Damage to the Hamstring Graft due to Interaction with Fixation Material and its Effect on Biomechanical Properties of ACL Reconstruction].

PubMed

Kautzner, J; Držík, M; Handl, M; Povýšil, C; Kos, P; Trč, T; Havlas, V

2017-01-01

PURPOSE OF THE STUDY Hamstring grafts are commonly used for ACL reconstruction. The purpose of our study is to determine the effects of the suspension fixation compared to graft cross-pinning transfixation, and the effect(s) of structural damage during the preparation of the graft on biomechanical properties of the graft. MATERIAL AND METHODS The design of the study is a cadaveric biomechanical laboratory study. 38 fresh-frozen human hamstring specimens from 19 cadaveric donors were used. The grafts were tested for their loading properties. One half of each specimen was suspended over a 3.3mm pin, the other half was cross-pinned by a 3.3mm pin to simulate the graft cross-pinning technique. Single impact testing was performed and the failure force, elongation and acceleration/deceleration of each graft was recorded and the loading force vs. elongation of the graft specimens was calculated. Results for suspended and cross-pinned grafts were analysed using ANOVA method, comparing the grafts from each donor. RESULTS The ultimate strength of a double-strand gracilis graft was 1287 ± 134 N when suspended over a pin, the strength of a cross-pinned graft was 833 ± 111 N. For double-strand semitendinosus grafts the strengths were 1883 ± 198 and 997 ± 234 N, respectively. Thus, the failure load for the cross-pinning method is only 64.7% or 52.9% for the suspension method. DISCUSSION Structural damage to the graft significantly reduces the graft strength. Also, extensive suturing during preparation of the graft reduces its strength. CONCLUSIONS Fixation methods that do not interfere with the graft's structure should be used to reduce the risk of graft failure. Key words: ACL reconstruction, hamstring graft, biomechanical testing.

Biomechanical Changes in the Sclera of Monkey Eyes Exposed to Chronic IOP Elevations

PubMed Central

Girard, Michaël J. A.; Suh, J.-K. Francis; Bottlang, Michael; Burgoyne, Claude F.

2011-01-01

Purpose. To characterize scleral biomechanics in both eyes of eight monkeys in which chronic intraocular pressure (IOP) elevation was induced in one eye. Methods. Each posterior sclera was mounted on a pressurization apparatus, IOP was elevated from 5 to 45 mm Hg while the 3D displacements of the scleral surface were measured by speckle interferometry. Finite element (FE) models of each scleral shell were constructed that incorporated stretch-induced stiffening and multidirectionality of the collagen fibers. FE model predictions were then iteratively matched to experimental displacements to extract unique sets of scleral biomechanical properties. Results. For all eyes, the posterior sclera exhibited inhomogeneous, anisotropic, nonlinear biomechanical behavior. Biomechanical changes caused by chronic IOP elevation were complex and specific to each subject. Specifically: (1) Glaucomatous eyes in which the contralateral normal eyes displayed large modulus or thickness were less prone to biomechanical changes; (2) glaucomatous scleral modulus associated with an IOP of 10 mm Hg decreased (when compared with that of the contralateral normal) after minimal chronic IOP elevation; (3) glaucomatous scleral modulus associated with IOPs of 30 and 45 mm Hg increased (when compared with that of the contralateral normal) after moderate IOP elevation; and (4) FE-based estimates of collagen fiber orientation demonstrated no change in the glaucomatous eyes. Conclusions. Significant stiffening of the sclera follows exposure to moderate IOP elevations in most eyes. Scleral hypercompliance may precede stiffening or be a unique response to minimal chronic IOP elevation in some eyes. These biomechanical changes are likely to be the result of scleral extracellular matrix remodeling. PMID:21519033

Biomechanical comparison of single-row, double-row, and transosseous-equivalent repair techniques after healing in an animal rotator cuff tear model.

PubMed

Quigley, Ryan J; Gupta, Akash; Oh, Joo-Han; Chung, Kyung-Chil; McGarry, Michelle H; Gupta, Ranjan; Tibone, James E; Lee, Thay Q

2013-08-01

The transosseous-equivalent (TOE) rotator cuff repair technique increases failure loads and contact pressure and area between tendon and bone compared to single-row (SR) and double-row (DR) repairs, but no study has investigated if this translates into improved healing in vivo. We hypothesized that a TOE repair in a rabbit chronic rotator cuff tear model would demonstrate a better biomechanical profile than SR and DR repairs after 12 weeks of healing. A two-stage surgical procedure was performed on 21 New Zealand White Rabbits. The right subscapularis tendon was transected and allowed to retract for 6 weeks to simulate a chronic tear. Repair was done with the SR, DR, or TOE technique and allowed to heal for 12 weeks. Cyclic loading and load to failure biomechanical testing was then performed. The TOE repair showed greater biomechanical characteristics than DR, which in turn were greater than SR. These included yield load (p < 0.05), energy absorbed to yield (p < 0.05), and ultimate load (p < 0.05). For repair of a chronic, retracted rotator cuff tear, the TOE technique was the strongest biomechanical construct after healing followed by DR with SR being the weakest. Copyright © 2013 Orthopaedic Research Society.

Does knowledge of seat design and whiplash injury mechanisms translate to understanding outcomes?

PubMed

Ivancic, Paul C

2011-12-01

Review of whiplash injury mechanisms and effects of anti-whiplash systems including active head restraint (AHR) and Whiplash Protection System (WHIPS). This article provides an overview of previous biomechanical and epidemiological studies of AHR and WHIPS and investigates whether seat design and biomechanical knowledge of proposed whiplash injury mechanisms translates to understanding outcomes of rear crash occupants. In attempt to reduce whiplash injuries, some newer automobiles incorporate anti-whiplash systems such as AHR or WHIPS. During a rear crash, mechanically based systems activate by occupant momentum pressing into the seatback whereas electronically based systems activate using crash sensors and an electronic control unit linked to the head restraint. To investigate the effects of AHR and WHIPS on occupant responses including head and neck loads and motions, biomechanical studies of simulated rear crashes have been performed using human volunteers, mathematical models, crash dummies, whole cadavers, and hybrid cadaveric/surrogate models. Epidemiological studies have evaluated the effects of AHR and WHIPS on reducing whiplash injury claims and lessening subjective complaints of neck pain after rear crashes. RESULTS.: Biomechanical studies indicate that AHR and WHIPS reduced the potential for some whiplash injuries but did not completely eliminate the injury risk. Epidemiological outcomes indicate reduced whiplash injury claims or subjective complaints of crash-related neck pain between 43 and 75% due to AHR and between 21% and 49% due to WHIPS as compared to conventional seats and head restraints. Yielding energy-absorbing seats aim to reduce occupant loads and accelerations whereas AHRs aim to provide early head support to minimize head and neck motions. Continued objective biomechanical and epidemiological studies of anti-whiplash systems together with industry, governmental, and clinical initiatives will ultimately lead to reduced whiplash injuries through improved prevention strategies.

Soreness-related changes in three-dimensional running biomechanics following eccentric knee extensor exercise.

PubMed

Paquette, Max R; Peel, Shelby A; Schilling, Brian K; Melcher, Dan A; Bloomer, Richard J

2017-06-01

Runners often experience delayed onset muscle soreness (DOMS), especially of the knee extensors, following prolonged running. Sagittal knee joint biomechanics are altered in the presence of knee extensor DOMS but it is unclear how muscle soreness affects lower limb biomechanics in other planes of motion. The purpose of this study was to assess the effects of knee extensor DOMS on three-dimensional (3D) lower limb biomechanics during running. Thirty-three healthy men (25.8 ± 6.8 years; 84.1 ± 9.2 kg; 1.77 ± 0.07 m) completed an isolated eccentric knee extensor damaging protocol to elicit DOMS. Biomechanics of over-ground running at a set speed of 3.35 m s -1 ±5% were measured before eccentric exercise (baseline) and, 24 h and 48 h following exercise in the presence of knee extensor DOMS. Knee flexion ROM was reduced at 48 h (P = 0.01; d = 0.26), and peak knee extensor moment was reduced at 24 h (P = 0.001; d = 0.49) and 48 h (P < 0.001; d = 0.68) compared to baseline. Frontal and transverse plane biomechanics were unaffected by the presence of DOMS (P > 0.05). Peak positive ankle and knee joint powers and, peak negative knee joint power were all reduced from baseline to 24 h and 48 h (P < 0.05). These findings suggest that knee extensor DOMS greatly influences sagittal knee joint angular kinetics and, reduces sagittal power production at the ankle joint. However, knee extensor DOMS does not affect frontal and transverse plane lower limb joint biomechanics during running.

Hip joint biomechanics in those with and without post-traumatic knee osteoarthritis after anterior cruciate ligament injury.

PubMed

Wellsandt, E; Zeni, J A; Axe, M J; Snyder-Mackler, L

2017-12-01

Anterior cruciate ligament injury results in altered kinematics and kinetics in the knee and hip joints that persist despite surgical reconstruction and rehabilitation. Abnormal movement patterns and a history of osteoarthritis are risk factors for articular cartilage degeneration in additional joints. The purpose of this study was to determine if hip joint biomechanics early after anterior cruciate ligament injury and reconstruction differ between patients with and without post-traumatic knee osteoarthritis 5years after reconstruction. The study's rationale was that individuals who develop knee osteoarthritis after anterior cruciate ligament injury may also demonstrate large alterations in hip joint biomechanics. Nineteen athletes with anterior cruciate ligament injury completed standard gait analysis before (baseline) and after (post-training) extended pre-operative rehabilitation and at 6months, 1year, and 2years after reconstruction. Weightbearing knee radiographs were completed 5years after reconstruction to identify medial compartment osteoarthritis. Five of 19 patients had knee osteoarthritis at 5years after anterior cruciate ligament reconstruction. Patients with knee osteoarthritis at 5years walked with smaller sagittal plane hip angles (P: 0.043) and lower sagittal (P: 0.021) and frontal plane (P: 0.042) external hip moments in the injured limb before and after reconstruction compared to those without knee osteoarthritis. The current findings suggest hip joint biomechanics may be altered in patients who develop post-traumatic knee osteoarthritis. Further study is needed to confirm whether the risk of non-traumatic hip pathology is increased after anterior cruciate ligament injury and if hip joint biomechanics influence its development. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biomechanical comparison of the human cadaveric pelvis with a fourth generation composite model.

PubMed

Girardi, Brandon L; Attia, Tarik; Backstein, David; Safir, Oleg; Willett, Thomas L; Kuzyk, Paul R T

2016-02-29

The use of cadavers for orthopaedic biomechanics research is well established, but presents difficulties to researchers in terms of cost, biosafety, availability, and ease of use. High fidelity composite models of human bone have been developed for use in biomechanical studies. While several studies have utilized composite models of the human pelvis for testing orthopaedic reconstruction techniques, few biomechanical comparisons of the properties of cadaveric and composite pelves exist. The aim of this study was to compare the mechanical properties of cadaveric pelves to those of the 4th generation composite model. An Instron ElectroPuls E10000 mechanical testing machine was used to load specimens with orientation, boundary conditions and degrees of freedom that approximated those occurring during the single legged phase of walking, including hip abductor force. Each specimen was instrumented with strain gauge rosettes. Overall specimen stiffness and principal strains were calculated from the test data. Composite specimens showed significantly higher overall stiffness and slightly less overall variability between specimens (composite K=1448±54N/m, cadaver K=832±62N/m; p<0.0001). Strains measured at specific sites in the composite models and cadavers were similar (but did differ) only when the applied load was scaled to overall construct stiffness. This finding regarding strain distribution and the difference in overall stiffness must be accounted for when using these composite models for biomechanics research. Altering the cortical wall thickness or tuning the elastic moduli of the composite material may improve future generations of the composite model. Copyright © 2016 Elsevier Ltd. All rights reserved.

Biomechanical Strength of Retrograde Fixation in Proximal Third Scaphoid Fractures.

PubMed

Daly, Charles A; Boden, Allison L; Hutton, William C; Gottschalk, Michael B

2018-04-01

Current techniques for fixation of proximal pole scaphoid fractures utilize antegrade fixation via a dorsal approach endangering the delicate vascular supply of the dorsal scaphoid. Volar and dorsal approaches demonstrate equivalent clinical outcomes in scaphoid wrist fractures, but no study has evaluated the biomechanical strength for fractures of the proximal pole. This study compares biomechanical strength of antegrade and retrograde fixation for fractures of the proximal pole of the scaphoid. A simulated proximal pole scaphoid fracture was produced in 22 matched cadaveric scaphoids, which were then assigned randomly to either antegrade or retrograde fixation with a cannulated headless compression screw. Cyclic loading and load to failure testing were performed and screw length, number of cycles, and maximum load sustained were recorded. There were no significant differences in average screw length (25.5 mm vs 25.6 mm, P = .934), average number of cyclic loading cycles (3738 vs 3847, P = .552), average load to failure (348 N vs 371 N, P = .357), and number of catastrophic failures observed between the antegrade and retrograde fixation groups (3 in each). Practical equivalence between the 2 groups was calculated and the 2 groups were demonstrated to be practically equivalent (upper threshold P = .010). For this model of proximal pole scaphoid wrist fractures, antegrade and retrograde screw configuration have been proven to be equivalent in terms of biomechanical strength. With further clinical study, we hope surgeons will be able to make their decision for fixation technique based on approaches to bone grafting, concern for tenuous blood supply, and surgeon preference without fear of poor biomechanical properties.

The Preventing Australian Football Injuries with Exercise (PAFIX) Study: a group randomised controlled trial

PubMed Central

Finch, C; Lloyd, D; Elliott, B

2009-01-01

Background: Knee injuries are a major injury concern for Australian Football players and participants of many other sports worldwide. There is increasing evidence from laboratory and biomechanically focused studies about the likely benefit of targeted exercise programmes to prevent knee injuries. However, there have been few international studies that have evaluated the effectiveness of such programmes in the real-world context of community sport that have combined epidemiological, behavioural and biomechanical approaches. Objective: To implement a fully piloted and tested exercise training intervention to reduce the number of football-related knee injuries. In so doing, to evaluate the intervention’s effectiveness in the real-world context of community football and to determine if the underlying neural and biomechanical training adaptations are associated with decreased risk of injury. Setting: Adult players from community-level Australian Football clubs in two Australian states over the 2007–08 playing seasons. Methods: A group-clustered randomised controlled trial with teams of players randomly allocated to either a coach-delivered targeted exercise programme or usual behaviour (control). Epidemiological component: field-based injury surveillance and monitoring of training/game exposures. Behavioural component: evaluation of player and coach attitudes, knowledge, behaviours and compliance, both before and after the intervention is implemented. Biomechanical component: biomechanical, game mobility and neuromuscular parameters assessed to determine the fundamental effect of training on these factors and injury risk. Outcome measures: The rate and severity of injury in the intervention group compared with the control group. Changes, if any, in behavioural components. Process evaluation: coach delivery factors and likely sustainability. PMID:19494090

Biomechanical investigation of different surgical strategies for the treatment of rib fractures using a three-dimensional human respiratory model.

PubMed

Shih, Kao-Shang; Truong, Thanh An; Hsu, Ching-Chi; Hou, Sheng-Mou

2017-11-02

Rib fracture is a common injury and can result in pain during respiration. Conservative treatment of rib fracture is applied via mechanical ventilation. However, ventilator-associated complications frequently occur. Surgical fixation is another approach to treat rib fractures. Unfortunately, this surgical treatment is still not completely defined. Past studies have evaluated the biomechanics of the rib cage during respiration using a finite element method, but only intact conditions were modelled. Thus, the purpose of this study was to develop a realistic numerical model of the human rib cage and to analyse the biomechanical performance of intact, injured and treated rib cages. Three-dimensional finite element models of the human rib cage were developed. Respiratory movement of the human rib cage was simulated to evaluate the strengths and limitations of different scenarios. The results show that a realistic human respiratory movement can be simulated and the predicted results were closely related to previous study (correlation coefficient>0.92). Fixation of two fractured ribs significantly decreased the fixation index (191%) compared to the injured model. This fixation may provide adequate fixation stability as well as reveal lower bone stress and implant stress compared with the fixation of three or more fractured ribs.

The biomechanical stability of a novel spacer with integrated plate in contiguous two-level and three-level ACDF models: an in vitro cadaveric study.

PubMed

Clavenna, Andrew L; Beutler, William J; Gudipally, Manasa; Moldavsky, Mark; Khalil, Saif

2012-02-01

Anterior cervical plating increases stability and hence improves fusion rates to treat cervical spine pathologies, which are often symptomatic at multiple levels. However, plating is not without complications, such as dysphagia, injury to neural elements, and plate breakage. The biomechanics of a spacer with integrated plate system combined with posterior instrumentation (PI), in two-level and three-level surgical models, has not yet been investigated. The purpose of the study was to biomechanically evaluate the multidirectional rigidity of spacer with integrated plate (SIP) at multiple levels as comparable to traditional spacers and plating. An in vitro cervical cadaveric model. Eight fresh human cervical (C2-C7) cadaver spines were tested under pure moments of ±1.5 Nm on spine simulator test frame. Each spine was tested in intact condition, with only anterior fixation and with both anterior and PI. Range of motion (ROM) was measured using Optotrak Certus (NDI, Inc., Waterloo, Ontario, Canada) motion analysis system in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) at the instrumented levels (C3-C6). Repeated-measures analysis of variance was used for statistical analysis. All the surgical constructs showed significant reduction in motion compared with intact condition. In two-level fusion, SIP (C4-C6) construct significantly reduced ROM by 66.5%, 65.4%, and 60.3% when compared with intact in FE, LB, and AR, respectively. In three-level fusion, SIP (C3-C6) construct significantly reduced ROM by 65.8%, 66%, and 49.6% when compared with intact in FE, LB, and AR, respectively. Posterior instrumentation showed significant stability only in three-level fusion when compared with their respective anterior constructs. In both two-level and three-level fusion, SIP showed comparable stability to traditional spacer and plate constructs in all loading modes. The anatomically profiled spacer with integrated plate allows treatment of cervical disorders with fewer steps and less impact to cervical structures. In this biomechanical study, spacer with integrated plate construct showed comparable stability to traditional spacer and plate for two-level and three-level fusion. Posterior instrumentation showed significant effect only in three-level fusion. Clinical data are required for further validation of using spacer with integrated plate at multiple levels. Copyright © 2012 Elsevier Inc. All rights reserved.

Comparison of corneal biomechanics in Sjögren's syndrome and non-Sjögren's syndrome dry eyes by Scheimpflug based device.

PubMed

Long, Qin; Wang, Jing-Yi; Xu, Dong; Li, Ying

2017-01-01

To compare the corneal biomechanics of Sjögren's syndrome (SS) and non-SS dry eyes with Corneal Visualization Scheimpflug Technology (CorVis ST). Corneal biomechanics and tear film parameters, namely the Schirmer I test value, tear film break-up time (TBUT) and corneal staining score (CSS) were detected in 34 eyes of 34 dry eye patients with SS (SSDE group) and 34 dry eye subjects without SS (NSSDE group) using CorVis ST. The differences of the above parameters between the two groups were examined, and the relationship between corneal biomechanics and tear film parameters were observed. The differences in age, sex, intraocular pressure (IOP) and central corneal thickness (CCT) were not significant between the two groups ( P >0.05). The tear film parameters had significant differences between the SSDE group and NSSDE group (all P <0.05). Patients in the SSDE group had significantly lower A1-time and HC-time, but higher DA ( P =0.01, 0.02, and 0.02, respectively) compared with the NSSDE group. In the SSDE group, DA was negatively correlated with TBUT ( rho =-0.38, P =0.03); HC-time was negatively correlated with CSS ( rho =-0.43, P =0.02). In the NSSDE group, HC-time was again negatively correlated with CSS ( rho =-0.39, P =0.02). There are differences in corneal biomechanical properties between SSDE and NSSDE. The cornea of SSDE tends to show less "stiffness", as seen by a significantly shorter A1-time and HC-time, but larger DA, compared with the cornea of NSSDE. Biomechanical parameters can be influenced by different tear film parameters in both groups.

Biomechanics of an orthosis-managed cranial cruciate ligament-deficient canine stifle joint predicted by use of a computer model.

PubMed

Bertocci, Gina E; Brown, Nathan P; Mich, Patrice M

2017-01-01

OBJECTIVE To evaluate effects of an orthosis on biomechanics of a cranial cruciate ligament (CrCL)-deficient canine stifle joint by use of a 3-D quasistatic rigid-body pelvic limb computer model simulating the stance phase of gait and to investigate influences of orthosis hinge stiffness (durometer). SAMPLE A previously developed computer simulation model for a healthy 33-kg 5-year-old neutered Golden Retriever. PROCEDURES A custom stifle joint orthosis was implemented in the CrCL-deficient pelvic limb computer simulation model. Ligament loads, relative tibial translation, and relative tibial rotation in the orthosis-stabilized stifle joint (baseline scenario; high-durometer hinge]) were determined and compared with values for CrCL-intact and CrCL-deficient stifle joints. Sensitivity analysis was conducted to evaluate the influence of orthosis hinge stiffness on model outcome measures. RESULTS The orthosis decreased loads placed on the caudal cruciate and lateral collateral ligaments and increased load placed on the medial collateral ligament, compared with loads for the CrCL-intact stifle joint. Ligament loads were decreased in the orthosis-managed CrCL-deficient stifle joint, compared with loads for the CrCL-deficient stifle joint. Relative tibial translation and rotation decreased but were not eliminated after orthosis management. Increased orthosis hinge stiffness reduced tibial translation and rotation, whereas decreased hinge stiffness increased internal tibial rotation, compared with values for the baseline scenario. CONCLUSIONS AND CLINICAL RELEVANCE Stifle joint biomechanics were improved following orthosis implementation, compared with biomechanics of the CrCL-deficient stifle joint. Orthosis hinge stiffness influenced stifle joint biomechanics. An orthosis may be a viable option to stabilize a CrCL-deficient canine stifle joint.

The biomechanical differences between barefoot and shod distance running: a systematic review and preliminary meta-analysis.

PubMed

Hall, Jonathan P L; Barton, Christian; Jones, Paul Remy; Morrissey, Dylan

2013-12-01

Distance running continues to experience increased participation in the Western world, although it is associated with high injury rates. Barefoot running has been increasingly proposed as a means to prevent overuse injury due to various biomechanical differences, including reduced joint loading rates and altered kinematics and muscle activity patterns compared to shod running. The aim of this review was to systematically evaluate biomechanical differences between running barefoot and shod, including the quality of available evidence, in order to provide guidance on the phenomenon of barefoot running to the running and sports medicine communities. A comprehensive search of MEDLINE, Web of Knowledge and EMBASE from inception to January 2013 was performed. Trials evaluating injury-free recreational or competitive adults who participate in long-distance running (≥5 km), where a comparison of barefoot and shod running lower-limb kinetics, kinematics and/or electromyography were included. Studies examining sprinting and studies of single-subject design were excluded. Following initial searching, two reviewers identified a shortlist of relevant studies based on title and abstract, with the full text of these studies being tested against the inclusion criteria. References of included studies were examined and citation tracking was performed in Web of Knowledge. Two independent reviewers evaluated the methodological quality of each included study using a modified version of the Downs and Black quality index. Results of the quality assessment were used to identify high- and low-quality studies, data pooling was completed where possible and levels of evidence were determined based on the van Tulder criteria. Eighteen studies were identified, all of low methodological quality. Effect size (ES) calculation was possible for 12 studies. Pooled results indicate moderate evidence that barefoot running is associated with reduced peak ground reaction force (GRF), increased foot and ankle plantarflexion and increased knee flexion at ground contact compared with running in a neutral shoe. Limited evidence indicates barefoot running is associated with reduced impact GRF, reduced peak knee flexion and varus joint moments, and a higher stride frequency compared to a neutral shoe. Very limited to limited evidence also indicates power absorption at the knee is decreased while being increased at the ankle whilst barefoot running. Additionally, the effects of barefoot running on loading rate appear dependent on strike pattern adopted, with a forefoot strike pattern found to reduce loading rate, whilst a rearfoot strike pattern increases loading rate when running barefoot compared to shod. Key methodological weaknesses that must be addressed in future research were identified. Of particular note were absence of investigator blinding, infrequent intervention randomisation, small sample sizes and lack of evaluation following habituation. Two studies could not be retrieved because of publication in a non-English-language journal. Of particular note is that the validity of the body of work is compromised by the lack of evaluation after habituation, or re-training, of previously shod rearfoot-striking runners to barefoot forefoot-striking running styles. There has been a great deal of publicity for barefoot running, and many claims made about its effects and risks. Despite a large amount of biomechanical data available for meta-analysis, clear guidance for clinical practice is limited because of the low methodological quality of the associated studies. Preliminary biomechanical differences identified suggest barefoot running may be associated with positive biomechanical changes in regards to injury prevention, although this may be dependent on strike pattern adopted. Further research employing more robust methodology, which addresses weaknesses highlighted in this review, is needed to confirm current preliminary evidence. Additionally, prospective research would have higher validity were the biomechanical effects of habituating to barefoot running fully examined alongside an evaluation of prevention of repetitive use injury.

Characterization of Ocular Biomechanics in Pellucid Marginal Degeneration.

PubMed

Lenk, Janine; Haustein, Michael; Terai, Naim; Spoerl, Eberhard; Raiskup, Frederik

2016-04-01

This study sought to investigate the diagnostic capacity of corneal biomechanical response parameters in a group of patients with pellucid marginal degeneration (PMD) using the Ocular Response Analyzer (ORA) and Corvis ST devices. In this prospective clinical study, we used the Corvis ST and ORA devices to investigate the ocular biomechanics of patients with PMD. Eighty-one eyes were included, and 2 study groups were formed: the PMD group (the study group, n = 29) and the control group (n = 52). We focused on 13 biomechanical parameters. Statistical analysis was performed using SPSS. Biomechanical parameters for the 2 groups were compared using analysis of covariance. The ORA results demonstrated that the Keratoconus Match Index was significantly lower in the PMD group than in the control group (0.031 ± 0.37 vs. 0.79 ± 0.33; P = 0.001). The 2 groups did not significantly differ with respect to intraocular pressure- and central corneal thickness-adjusted values for corneal hysteresis or corneal resistance factor. Regarding the Corvis parameters, differences between the control and PMD groups were detected for CorWmax amp (control 1.01 ± 0.01, PMD 1.06 ± 0.01; P = 0.020) and CorA2 t (control 21.78 ± 0.03, PMD 21.66 ± 0.04; P = 0.0003). We identified 2 Corvis parameters that could be used to characterize PMD and differentiate PMD corneas from normal corneas. These parameters support the hypothesis that there is significantly less deformation of the central cornea in PMD corneas than in healthy corneas. However, because useful "first-line" diagnostic devices for diagnosing PMD (such as Pentacam and the ORA) exist, the Corvis ST serves as an additional diagnostic tool that can also be used for long-term monitoring after diagnosis confirmation.

Single- and double-row repair for rotator cuff tears - biology and mechanics.

PubMed

Papalia, Rocco; Franceschi, Francesco; Vasta, Sebastiano; Zampogna, Biagio; Maffulli, Nicola; Denaro, Vincenzo

2012-01-01

We critically review the existing studies comparing the features of single- and double-row repair, and discuss suggestions about the surgical indications for the two repair techniques. All currently available studies comparing the biomechanical, clinical and the biological features of single and double row. Biomechanically, the double-row repair has greater performances in terms of higher initial fixation strength, greater footprint coverage, improved contact area and pressure, decreased gap formation, and higher load to failure. Results of clinical studies demonstrate no significantly better outcomes for double-row compared to single-row repair. Better results are achieved by double-row repair for larger lesions (tear size 2.5-3.5 cm). Considering the lack of statistically significant differences between the two techniques and that the double row is a high cost and a high surgical skill-dependent technique, we suggest using the double-row technique only in strictly selected patients. Copyright © 2012 S. Karger AG, Basel.

A biomechanical cadaveric study comparing superior capsule reconstruction using fascia lata allograft with human dermal allograft for irreparable rotator cuff tear.

PubMed

Mihata, Teruhisa; Bui, Christopher N H; Akeda, Masaki; Cavagnaro, Matthew A; Kuenzler, Michael; Peterson, Alexander B; McGarry, Michelle H; Itami, Yasuo; Limpisvasti, Orr; Neo, Masashi; Lee, Thay Q

2017-12-01

Biomechanical and clinical success of the superior capsule reconstruction (SCR) using fascia lata (FL) grafts has been reported. In the United States, human dermal (HD) allograft has been used successfully for SCRs; however, the biomechanical characteristics have not been reported. Eight cadaveric shoulders were tested in 5 conditions: (1) intact; (2) irreparable supraspinatus tear; (3) SCR using FL allograft with anterior and posterior suturing; (4) SCR using HD allograft with anterior and posterior suturing; and (5) SCR using HD allograft with posterior suturing. Rotational range of motion, superior translation, glenohumeral joint force, and subacromial contact were measured at 0°, 30°, and 60° of glenohumeral abduction in the scapular plane. Graft dimensions before and after testing were also recorded. Biomechanical parameters were compared using a repeated-measures analysis of variance with Tukey post hoc test, and graft dimensions were compared using a Student t-test (P < .05). Irreparable supraspinatus tear significantly increased superior translation, superior glenohumeral joint force, and subacromial contact pressure, which were completely restored with the SCR FL allografts. Both SCR HD allograft repairs partially restored superior translation and completely restored subacromial contact and superior glenohumeral joint force. The HD allografts significantly elongated by 15% during testing, whereas the FL allograft lengths were unchanged. Single-layered HD SCR allografts partially restored superior glenohumeral stability, whereas FL allograft SCR completely restored the superior glenohumeral stability. This may be due to the greater flexibility of the HD allograft, and the SCR procedure used was developed on the basis of FL grafts. Published by Elsevier Inc.

Quadriceps Strength Asymmetry After Anterior Cruciate Ligament Reconstruction Alters Knee Joint Biomechanics and Functional Performance at Time of Return to Activity.

PubMed

Palmieri-Smith, Riann M; Lepley, Lindsey K

2015-07-01

Quadriceps strength deficits are observed clinically after anterior cruciate ligament (ACL) injury and reconstruction and are often not overcome despite rehabilitation. Given that quadriceps strength may be important for achieving symmetrical joint biomechanics and promoting long-term joint health, determining the magnitude of strength deficits that lead to altered mechanics is critical. To determine if the magnitude of quadriceps strength asymmetry alters knee and hip biomechanical symmetry as well as functional performance and self-reported function. Cross-sectional study; Level of evidence, 3. A total of 73 patients were tested at the time they were cleared for return to activity after ACL reconstruction. Quadriceps strength and activation, scores on the International Knee Documentation Committee form, the hop for distance test, and sagittal plane lower extremity biomechanics were recorded while patients completed a single-legged hop. Patients with high and moderate quadriceps strength symmetry had larger central activation ratios as well as greater limb symmetry indices on the hop for distance compared with patients with low quadriceps strength symmetry (P < .05). Similarly, knee flexion angle and external moment symmetry were higher in the patients with high and moderate quadriceps symmetry compared with those with low symmetry (P < .05). Quadriceps strength was found to be associated with sagittal plane knee angle and moment symmetry (P < .05). Patients with low quadriceps strength displayed greater movement asymmetries at the knee in the sagittal plane. Quadriceps strength was related to movement asymmetries and functional performance. Rehabilitation after ACL reconstruction needs to focus on maximizing quadriceps strength, which likely will lead to more symmetrical knee biomechanics. © 2015 The Author(s).

The Effect of Pterygium and Pterygium Surgery on Corneal Biomechanics.

PubMed

Koç, Mustafa; Yavrum, Fuat; Uzel, Mehmet Murat; Aydemir, Emre; Özülken, Kemal; Yılmazbaş, Pelin

2018-01-01

To evaluate the effect of pterygium and pterygium surgery on corneal biomechanics by ocular response analyzer (ORA, Reichert, USA). This study considered 68 eyes (from 34 patients with a mean age of 21.2±7.1 years) with unilateral nasal, primary pterygium (horizontal length <4 mm), and having undergone pterygium excision and conjunctival autografting. Pterygium length and area were measured from a photograph of the anterior segment using Image J program. ORA measurements were obtained before surgery and after the first month of the surgery. The measurements of the eyes with pterygium and healthy eyes were compared to evaluate the effect of pterygium. Similarly, measurements obtained before and after surgery were compared to evaluate the effect of pterygium surgery on corneal biomechanics. The correlation of the ORA measurements with the pterygium area was evaluated. Mean pterygium horizontal length and area were 3.31±1.43 mm and 6.82±2.17 mm 2 , respectively. There was no statistically significant difference between the eyes with and without pterygium in corneal hysteresis (CH, p=0.442), corneal resistance factor (CRF, p=0.554), corneal-compensated intraocular pressure (IOP cc , p=0.906), and Goldmann-correlated IOP (IOP g , p=0.836). All preoperative parameters decreased after surgery; however, none of them were statistically significant (CH, p=0.688; CRF, p=0.197; IOP cc , p=0.503; IOP g , p=0.231). There were no correlations between pterygium area and ORA measurements (p>0.05). Pterygium <4 mm and its surgical excision did not affect corneal biomechanics. These results may be taken into account when cornea biomechanics, mainly intraocular pressure measurements, are important.

Biomechanical and morphological peculiarities of the rectum in patients with obstructed defecation syndrome.

PubMed

Brunenieks, Ints; Pekarska, Katrina; Kasyanov, Vladimir; Groma, Valerija

2017-01-01

The morphological and biomechanical peculiarities of the rectum observed in obstructed defecation syndrome (ODS) are not completely understood. The biomechanical properties and morphological features of the rectum in patients with ODS in correlation with the status of the enteric nervous system (ENS) were evaluated. Uniaxial tensile tests on the rectum samples of patients with ODS and controls were performed; collagenous constituents were assessed by Reticulin and Masson's trichrome stainings; the expressions of α-smooth muscle actin (α-SMA), S100 and CD117 labeling of interstitial cells of Cajal (ICCs) were investigated by immunohistochemistry. In both groups, the ultimate stress in the posterior rectal wall was statistically significantly higher compared to the anterior one. The ultimate strain was higher in ODS compared to controls. The tangential modulus of elasticity was significantly higher in the control group than in the ODS one, both in the anterior and posterior walls. A significantly higher density of collagen demonstrated throughout the wall was evidenced in controls compared to ODS. The mucosal muscular compartment was significantly thicker but more disorganized in the patients group. The enteric S100-positive glial cells were significantly reduced in number in the anterior wall, but elevated in the posterior wall of the rectum in ODS simultaneously demonstrating the higher numbers of ICCs within the entire muscular layer and myenteric. The biomechanical and morphological results show that the rectal wall in patients with ODS is more deformable and less rigid compared to controls. The results of biomechanical properties and morphological changes in the human rectum are essential when choosing the method of ODS treatment.

A Comparative Biomechanical Analysis of 2 Double-Row, Distal Triceps Tendon Repairs

PubMed Central

Dorweiler, Matthew A.; Van Dyke, Rufus O.; Siska, Robert C.; Boin, Michael A.; DiPaola, Mathew J.

2017-01-01

Background: Triceps tendon ruptures are rare orthopaedic injuries that almost always require surgical repair. This study tests the biomechanical properties of an original anchorless double-row triceps repair against a previously reported knotless double-row repair. Hypothesis: The anchorless double-row triceps repair technique will yield similar biomechanical properties when compared with the knotless double-row repair technique. Study Design: Controlled laboratory study. Methods: Eighteen cadaver arms were randomized into 2 groups. One group received the anchorless repair and the other received the knotless anchor repair. A materials testing system (MTS) machine was used to cycle the repaired arms from 0° to 90° with a 2.5-pound weight for 1500 cycles at 0.25 Hz. Real-time displacement of the tendon was measured during cycling using a probe. Load to failure was performed after completion of cyclic loading. Results: The mean displacement with the anchorless technique was 0.77 mm (SD, 0.25 mm) at 0° (full elbow extension) and 0.76 mm (SD, 0.38 mm) at 90° (elbow flexion). The mean displacement with the anchored technique was 0.83 mm (SD, 0.57 mm) at 0° and 1.01 mm (SD, 0.62 mm) at 90°. There was no statistically significant difference for tendon displacement at 0º (P = .75) or 90º (P = .31). The mean load to failure with the anchorless technique was 618.9 N (SD, 185.6 N), while it was 560.5 N (SD, 154.1 N) with the anchored technique, again with no statistically significant difference (P = .28). Conclusion: Our anchorless double-row triceps repair technique yields comparable biomechanical properties to previously described double-row triceps tendon repair techniques, with the added benefit of avoiding the cost of suture anchors. Clinical Relevance: This anchorless double-row triceps tendon repair can be considered as an acceptable alternative to a knotless anchor repair for triceps tendon ruptures. PMID:28607942

Positive outcomes following gait therapy intervention for hip osteoarthritis: A longitudinal study.

PubMed

Solomonow-Avnon, Deborah; Herman, Amir; Levin, Daniel; Rozen, Nimrod; Peled, Eli; Wolf, Alon

2017-10-01

Footwear-generated biomechanical manipulation of lower-limb joints was shown to beneficially impact gait and quality of life in knee osteoarthritis patients, but has not been tested in hip osteoarthritis patients. We examined a customized gait treatment program using a biomechanical device shown in previous investigations to be capable of manipulating hip biomechanics via foot center of pressure (COP) modulation. The objective of this study was to assess the treatment program for hip osteoarthritis patients, enrolled in a 1-year prospective investigation, by means of objective gait and spatiotemporal parameters, and subjective quality of life measures. Gait analysis and completion of questionnaires were performed at the start of the treatment (baseline), and after 3, 6, and 12 months. Outcome parameters were evaluated over time using linear mixed effects models, and association between improvement in quality of life measures and change in objective outcomes was tested using mixed effect linear regression models. Quality of life measures improved compared to baseline, accompanied by increased gait speed and cadence. Sagittal-plane hip joint kinetics, kinematics, and spatiotemporal parameters changed throughout the study compared to baseline, in a manner suggesting improvement of gait. The most substantial improvement occurred within 3 months after treatment initiation, after which improvement approximately plateaued, but was sustained at 12 months. Speed and cadence, as well as several sagittal-plane gait parameters, were significant predictors of improvement in quality of life. Evidence suggests that a biomechanical gait therapy program improves subjective and objective outcomes measures and is a valid treatment option for hip osteoarthritis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2222-2232, 2017. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Sterilization with electron beam irradiation influences the biomechanical properties and the early remodeling of tendon allografts for reconstruction of the anterior cruciate ligament (ACL).

PubMed

Schmidt, Tanja; Hoburg, Arnd; Broziat, Christine; Smith, Mark D; Gohs, Uwe; Pruss, Axel; Scheffler, Sven

2012-08-01

Although allografts for anterior cruciate ligament (ACL) replacement have shown advantages compared to autografts, their use is limited due to the risk of disease transmission and the limitations of available sterilization methods. Gamma sterilization has shown detrimental effects on graft properties at the high doses required for sufficient pathogen inactivation. In our previous in vitro study on human patellar tendon allografts, Electron beam (Ebeam) irradiation showed less detrimental effects compared to gamma sterilization (Hoburg et al. in Am J Sports Med 38(6):1134-1140, 2010). To investigate the biological healing and restoration of the mechanical properties of a 34 kGy Ebeam treated tendon allograft twenty-four sheep underwent ACL replacement with either a 34 kGy Ebeam treated allograft or a non-sterilized fresh frozen allograft. Biomechanical testing of stiffness, ultimate failure load and AP-laxity as well as histological analysis to investigate cell, vessel and myofibroblast-density were performed after 6 and 12 weeks. Native sheep ACL and hamstring tendons (HAT, each n = 9) served as controls. The results of a previous study analyzing the remodeling of fresh frozen allografts (n = 12) and autografts (Auto, n = 18) with the same study design were also included in the analysis. Statistics were performed using Mann-Whitney U test followed by Bonferroni-Holm correction. Results showed significantly decreased biomechanical properties during the early remodeling period in Ebeam treated grafts and this was accompanied with an increased remodeling activity. There was no recovery of biomechanical function from 6 to 12 weeks in this group in contrast to the results observed in fresh frozen allografts and autografts. Therefore, high dose Ebeam irradiation investigated in this paper cannot be recommended for soft tissue allograft sterilization.

Biomechanical study of four kinds of percutaneous screw fixation in two types of unilateral sacroiliac joint dislocation: a finite element analysis.

PubMed

Zhang, Lihai; Peng, Ye; Du, Chengfei; Tang, Peifu

2014-12-01

To compare the biomechanical stability of four different kinds of percutaneous screw fixation in two types of unilateral sacroiliac joint dislocation. Finite element models of unstable Tile type B and type C pelvic ring injuries were created in this study. Modelling was based on fixation with a single S1 screw (S1-1), single S2 screw (S2-1), two S1 screws (S1-2) and a combination of a single S1 and a single S2 screw (S1–S2). The biomechanical test of two types of pelvic instability (rotational or vertical) with four types of percutaneous fixation were compared. Displacement, flexion and lateral bend (in bilateral stance) were recorded and analyzed. Maximal inferior translation (displacement) was found in the S2-1 group in type B and C dislocations which were 1.58 mm and 1.90 mm, respectively. Maximal flexion was found in the S2-1 group in type B and C dislocations which were 1.55° and 1.95°, respectively. The results show that the flexion from most significant angulation to least is S2-1, S1-1, S1-2, and S1–S2 in type B and C dislocations. All the fixations have minimal lateral bend. Our findings suggest single screw S1 fixation should be adequate fixation for a type B dislocation. For type C dislocations, one might consider a two screw construct (S1–S2) to give added biomechanical stability if clinically indicated.

Musculoskeletal disorder symptoms in correction officers: why do they increase rapidly with job tenure?

PubMed

Warren, Nicholas; Dussetschleger, Jeffrey; Punnett, Laura; Cherniack, Martin G

2015-03-01

In this study, we sought to explain the rapid musculoskeletal symptomatology increase in correction officers (COs). COs are exposed to levels of biomechanical and psychosocial stressors that have strong associations with musculoskeletal disorders (MSDs) in other occupations, possibly contributing to their rapid health deterioration. Baseline survey data from a longitudinal study of COs and manufacturing line workers were used to model musculoskeletal symptom prevalence and intensity in the upper (UE) and lower (LE) extremity. Outcomes were regressed on demographics and biomechanical and psychosocial exposures. COs reported significantly higher prevalence and intensity of LE symptoms compared to the industrial workers. In regression models, job tenure was a primary driver of CO musculoskeletal outcomes. In CO models, a single biomechanical exposure, head and arms in awkward positions, explained variance in both UE and LE prevalence (β of 0.338 and 0.357, respectively), and low decision latitude was associated with increased LE prevalence and intensity (β of 0.229 and 0.233, respectively). Manufacturing models were less explanatory. Examining demographic associations with exposure intensity, we found none to be significant in manufacturing, but in CO models, important psychosocial exposure levels increased with job tenure. Symptom prevalence and intensity increased more rapidly with job tenure in corrections, compared to manufacturing, and were related to both biomechanical and psychosocial exposures. Tenure-related increases in psychosocial exposure levels may help explain the CO symptom increase. Although exposure assessment improvements are proposed, findings suggest focusing on improving the psychosocial work environment to reduce MSD prevalence and intensity in corrections. © 2014, Human Factors and Ergonomics Society.

Preliminary evidence of altered biomechanics in adolescents with Juvenile Fibromyalgia

PubMed Central

Sil, Soumitri; Thomas, Staci; DiCesare, Christopher; Strotman, Daniel; Ting, Tracy V; Myer, Gregory; Kashikar-Zuck, Susmita

2014-01-01

Objective Juvenile Fibromyalgia (JFM) is characterized by chronic musculoskeletal pain and marked reduction in physical activity. Despite recommendations for exercise to manage JFM pain, exercise adherence is poor. Due to pain and activity avoidance, adolescents with JFM are at risk for altered joint mechanics that may make them susceptible to increased pain and reduced tolerance for exercise. The primary aim of this study was to assess functional deficits in patients with JFM compared to healthy controls using objective biomechanical assessment. Methods Female adolescent patients with JFM (n=17) and healthy controls (n=14) completed biomechanical assessments including gait analysis and tests of lower extremity strength (isokinetic knee extension/flexion, hip abduction) and functional performance (Drop Vertical Jump) along with self-report measures of disability (Functional Disability Inventory), pain intensity, depressive symptoms (Children’s Depression Inventory), and fear of movement (Tampa Scale of Kinesiophobia). Results Patients with JFM demonstrated mild deficiencies in walking gait and functional performance (p’s <. 05), significantly lower left knee extension and flexion strength (19–26% deficit) and bilateral hip abduction strength (33–37%) compared to healthy controls (p’s < .008). Patients with JFM reported significantly higher functional disability, pain intensity, depressive symptoms, and fear of movement relative to controls (p’s < 0.01). Conclusions This study showed that adolescents with JFM exhibited objective alterations in biomechanics, and self-reported fear of movement which may reinforce their activity avoidance. Interventions for JFM should include a focus on correcting functional deficits and instilling greater confidence in adolescents with JFM to engage in exercise to improve functional outcomes. PMID:25156509

Varus knee osteoarthritis: Elevated synovial CD15 counts correlate with inferior biomechanical properties of lateral-compartment cartilage.

PubMed

Koller, Ulrich; Waldstein, Wenzel; Krenn, Veit; Windhager, Reinhard; Boettner, Friedrich

2018-03-01

The study analyzed the influence of synovitis on the histological and biomechanical properties of lateral-compartment cartilage. In a prospective cohort study, 84 patients (100 knees) with varus deformity of the knee were included. Osteochondral samples from the distal lateral femur underwent biomechanical and histologic analysis. Synovial tissue was sampled for histological (chronic synovitis score) and immunohistochemical evaluation of the degree of synovitis. CD15 (neutrophils), Ki-67 (dividing cells), and CD68 (macrophages) were tested in all synovial samples. While the histological synovitis score did not correlate with the degree of cartilage degeneration (histological OARSI grades), both CD15 (r s  = 0.297, p = 0.006) and Ki-67 (r s  = 0.249, p = 0.023) correlated with histological OARSI grades. There was a weak negative correlation of CD15 with biomechanical properties of cartilage of the distal lateral femur (aggregate modulus (Ha): r s  = -0.125; p = 0.257; dynamic modulus (DM): r s  = -0.216; p = 0.048). No correlations were observed for Ki-67 and CD68. In addition, biomechanical properties were inferior in knees with a CD15 of >8/high power field compared to knees with a CD15 of ≤8/high power field (Ha: p = 0.031, d = 0.46; DM: p = 0.005, d = 0.68). The study demonstrates an association of increased inflammatory activity with advanced cartilage degeneration. Lateral-compartment cartilage in knees with elevated synovial CD15 counts has a reduced ability to withstand compressive loads. CD15 might serve as an indicator for inferior biomechanical cartilage properties. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:841-846, 2018. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION USING THE DOUBLE-BUNDLE TECHNIQUE – EVALUATION IN THE BIOMECHANICS LABORATORY

PubMed Central

D'Elia, Caio Oliveira; Bitar, Alexandre Carneiro; Castropil, Wagner; Garofo, Antônio Guilherme Padovani; Cantuária, Anita Lopes; Orselli, Maria Isabel Veras; Luques, Isabela Ugo; Duarte, Marcos

2015-01-01

Objective: The objective of this study was to describe the methodology of knee rotation analysis using biomechanics laboratory instruments and to present the preliminary results from a comparative study on patients who underwent anterior cruciate ligament (ACL) reconstruction using the double-bundle technique. Methods: The protocol currently used in our laboratory was described. Three-dimensional kinematic analysis was performed and knee rotation amplitude was measured on eight normal patients (control group) and 12 patients who were operated using the double-bundle technique, by means of three tasks in the biomechanics laboratory. Results: No significant differences between operated and non-operated sides were shown in relation to the mean amplitudes of gait, gait with change in direction or gait with change in direction when going down stairs (p > 0.13). Conclusion: The preliminary results did not show any difference in the double-bundle ACL reconstruction technique in relation to the contralateral side and the control group. PMID:27027003

Biomechanical properties of the atlantoaxial joint with naturally-occurring instability in a toy breed dog. A comparative descriptive cadaveric study.

PubMed

Forterre, F; Precht, C; Riedinger, B; Bürki, A

2015-01-01

The biomechanical properties of the atlanto-axial joint in a young Yorkshire Terrier dog with spontaneous atlantoaxial instability were compared to those of another young toy breed dog with a healthy atlantoaxial joint. The range-of-motion was increased in flexion and lateral bending in the unstable joint. In addition, lateral bending led to torsion and dorsal dislocation of the axis within the atlas. On gross examination, the dens ligaments were absent and a longitudinal tear of the tectorial membrane was observed. These findings suggest that both ventral and lateral flexion may lead to severe spinal cord compression, and that the tectorial membrane may play a protective role in some cases of atlantoaxial instability.

Comminuted supracondylar femoral fractures: a biomechanical analysis comparing the stability of medial versus lateral plating in axial loading.

PubMed

Briffa, Nikolai; Karthickeyan, Raju; Jacob, Joshua; Khaleel, Arshad

2016-11-01

The aim of this study was to compare the biomechanical properties of medial and lateral plating of a medially comminuted supracondylar femoral fracture. A supracondylar femoral fracture model comparing two fixation methods was tested cyclically in axial loading. One-centimetre supracondylar gap osteotomies were created in six synthetic femurs approximately 6 cm proximal to the knee joint. There were two constructs investigated: group 1 and group 2 were stabilized with an 8-hole LC-DCP, medially and laterally, respectively. Both construct groups were axially loaded. Global displacement (total length), wedge displacement, bending moment and strain were measured. Medial plating showed a significantly decreased displacement, bending moment and strain at the fracture site in axial loading. Medial plating of a comminuted supracondylar femur fracture is more stable than lateral plating.

Important learning factors in high- and low-achieving students in undergraduate biomechanics.

PubMed

Hsieh, ChengTu; Knudson, Duane

2017-07-21

The purpose of the present study was to document crucial factors associated with students' learning of biomechanical concepts, particularly between high- and-low achieving students. Students (N = 113) from three introductory biomechanics classes at two public universities volunteered for the study. Two measures of students' learning were obtained, final course grade and improvement on the Biomechanics Concept Inventory version 3 administered before and after the course. Participants also completed a 15-item questionnaire documenting student learning characteristics, effort, and confidence. Partial correlations controlling for all other variables in the study, confirmed previous studies that students' grade point average (p < 0.01), interest in biomechanics, (p < 0.05), and physics credits passed (p < 0.05) are factors uniquely associated with learning biomechanics concepts. Students' confidence when encountering difficult biomechanics concepts was also significantly (p < 0.05) associated with final grade. There were significant differences between top 15% and bottom 15% achievers on these variables (p < 0.05), as well as on readings completed, work to pay for college per week, and learning epistemology. Consequently, instructors should consider strategies to promote students' interest in biomechanics and confidence in solving relevant professional problems in order to improve learning for both low- and high-ability students.

Biomechanical analysis of posteromedial tibial plateau split fracture fixation.

PubMed

Zeng, Zhi-Min; Luo, Cong-Feng; Putnis, Sven; Zeng, Bing-Fang

2011-01-01

The purpose of this study was to compare the biomechanical strength of four different fixation methods for a posteromedial tibial plateau split fracture. Twenty-eight tibial plateau fractures were simulated using right-sided synthetic tibiae models. Each fracture model was randomly instrumented with one of the four following constructs, anteroposterior lag-screws, an anteromedial limited contact dynamic compression plate (LC-DCP), a lateral locking plate, or a posterior T-shaped buttress plate. Vertical subsidence of the posteromedial fragment was measured from 500 N to 1500 N during biomechanical testing, the maximum load to failure was also determined. It was found that the posterior T-shaped buttress plate allowed the least subsidence of the posteromedial fragment and produced the highest mean failure load than each of the other three constructs (P=0.00). There was no statistical significant difference between using lag screws or an anteromedial LC-DCP construct for the vertical subsidence at a 1500 N load and the load to failure (P>0.05). This study showed that a posterior-based buttress technique is biomechanically the most stable in-vitro fixation method for posteromedial split tibial plateau fractures, with AP screws and anteromedial-based LC-DCP are not as stable for this type of fracture. Copyright © 2010 Elsevier B.V. All rights reserved.

Morphology and biomechanics of human heart

NASA Astrophysics Data System (ADS)

Chelnokova, Natalia O.; Golyadkina, Anastasiya A.; Kirillova, Irina V.; Polienko, Asel V.; Ivanov, Dmitry V.

2016-03-01

Object of study: A study of the biomechanical characteristics of the human heart ventricles was performed. 80 hearts were extracted during autopsy of 80 corpses of adults (40 women and 40 men) aged 31-70 years. The samples were investigated in compliance with the recommendations of the ethics committee. Methods: Tension and compression tests were performed with help of the uniaxial testing machine Instron 5944. Cardiometry was also performed. Results: In this work, techniques for human heart ventricle wall biomechanical properties estimation were developed. Regularities of age and gender variability in deformative and strength properties of the right and left ventricle walls were found. These properties were characterized by a smooth growth of myocardial tissue stiffness and resistivity at a relatively low strain against reduction in their strength and elasticity from 31-40 to 61-70 years. It was found that tissue of the left ventricle at 61-70 years had a lower stretchability and strength compared with tissues of the right ventricle and septum. These data expands understanding of the morphological organization of the heart ventricles, which is very important for the development of personalized medicine. Taking into account individual, age and gender differences of the heart ventricle tissue biomechanical characteristics allows to rationally choosing the type of patching materials during reconstructive operations on heart.

Maxillary incisors changes during space closure with conventional and skeletal anchorage methods: a systematic review.

PubMed

Jayaratne, Yasas Shri Nalaka; Uribe, Flavio; Janakiraman, Nandakumar

2017-01-01

The objective of this systematic review was to compare the antero-posterior, vertical and angular changes of maxillary incisors with conventional anchorage control techniques and mini-implant based space closure methods. The electronic databases Pubmed, Scopus, ISI Web of knowledge, Cochrane Library and Open Grey were searched for potentially eligible studies using a set of predetermined keywords. Full texts meeting the inclusion criteria as well as their references were manually searched. The primary outcome data (linear, angular, and vertical maxillary incisor changes) and secondary outcome data (overbite changes, soft tissue changes, biomechanical factors, root resorption and treatment duration) were extracted from the selected articles and entered into spreadsheets based on the type of anchorage used. The methodological quality of each study was assessed. Six studies met the inclusion criteria. The amount of incisor retraction was greater with buccally placed mini-implants than conventional anchorage techniques. The incisor retraction with indirect anchorage from palatal mini-implants was less when compared with buccally placed mini-implants. Incisor intrusion occurred with buccal mini-implants, whereas extrusion was seen with conventional anchorage. Limited data on the biomechanical variables or adverse effects such as root resorption were reported in these studies. More RCT's that take in to account relevant biomechanical variables and employ three-dimensional quantification of tooth movements are required to provide information on incisor changes during space closure.

Biomechanical study of tarsometatarsal joint fusion using finite element analysis.

PubMed

Wang, Yan; Li, Zengyong; Zhang, Ming

2014-11-01

Complications of surgeries in foot and ankle bring patients with severe sufferings. Sufficient understanding of the internal biomechanical information such as stress distribution, contact pressure, and deformation is critical to estimate the effectiveness of surgical treatments and avoid complications. Foot and ankle is an intricate and synergetic system, and localized intervention may alter the functions to the adjacent components. The aim of this study was to estimate biomechanical effects of the TMT joint fusion using comprehensive finite element (FE) analysis. A foot and ankle model consists of 28 bones, 72 ligaments, and plantar fascia with soft tissues embracing all the segments. Kinematic information and ground reaction force during gait were obtained from motion analysis. Three gait instants namely the first peak, second peak and mid-stance were simulated in a normal foot and a foot with TMT joint fusion. It was found that contact pressure on plantar foot increased by 0.42%, 19% and 37%, respectively after TMT fusion compared with normal foot walking. Navico-cuneiform and fifth meta-cuboid joints sustained 27% and 40% increase in contact pressure at second peak, implying potential risk of joint problems such as arthritis. Von Mises stress in the second metatarsal bone increased by 22% at midstance, making it susceptible to stress fracture. This study provides biomechanical information for understanding the possible consequences of TMT joint fusion. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

The Effect of Dehydration and Fasting on Corneal Biomechanical Properties and Intraocular Pressure.

PubMed

Oltulu, Refik; Satirtav, Gunhal; Ersan, Ismail; Soylu, Erkan; Okka, Mehmet; Zengin, Nazmi

2016-11-01

To evaluate the changes in corneal biomechanical properties and intraocular pressure (IOP) during fasting period in healthy subjects. Seventy-two eyes of 72 fasting subjects (study group), and 62 eyes of 62 nonfasting subjects (control group) were enrolled in this prospective study undertaken at a single university hospital. All subjects underwent complete ophthalmologic examination including ocular biomechanical evaluation with ocular response analyzer. Ocular response analyzer measurement was performed on the right eyes of the subjects between 5.00 and 6.00 PM after approximately 14 hr of fasting for the study group and after a nonfasting period for the control group. The corneal hysteresis, corneal resistance factor, mean corneal compensated IOP (IOPcc), and Goldmann-correlated IOP (IOPg) values were measured with a patented dynamic bidirectional applanation process. Goldmann-correlated IOP and IOPcc measurements in the study group and the control group were found as 13.8±2.8 mm Hg, 14.6±2.6 mm Hg and 16.3±2.2 mm Hg, 15.7±2.4 mm Hg, respectively. There was statistically significant difference within the two groups in IOPg and IOPcc (P<0.001). In addition, corneal hysteresis and corneal resistance factor significantly decreased in study group compared with control group (P<0.001, P=0.012, respectively). Prolonged fasting causes a significant decrease in IOPg, IOPcc, corneal hysteresis, and corneal resistance factor in healthy subjects, altering the biomechanical properties of the cornea.

Editorial Commentary: All-Suture Anchors, Foam Blocks, and Biomechanical Testing.

PubMed

Brand, Jefferson C

2017-06-01

Barber's biomechanical work is well known to Arthroscopy's readers as thorough, comprehensive, and inclusive of new designs as they become available. In "All-Suture Anchors: Biomechanical Analysis of Pullout Strength, Displacement, and Failure Mode," the latest iteration, Barber and Herbert test all-suture anchors in both porcine femurs and biphasic foam. While we await in vivo clinical trials that compare all-suture anchors to currently used anchors, Barber and Herbert have provided data to inform anchor choice, and using their biomechanical data at time zero from all-suture anchor trials in an animal model, we can determine the anchors' feasibility for human clinical investigations. Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Tissue engineering human small-caliber autologous vessels using a xenogenous decellularized connective tissue matrix approach: preclinical comparative biomechanical studies.

PubMed

Heine, Jörg; Schmiedl, Andreas; Cebotari, Serghei; Karck, Matthias; Mertsching, Heike; Haverich, Axel; Kallenbach, Klaus

2011-10-01

Suggesting that bioartificial vascular scaffolds cannot but tissue-engineered vessels can withstand biomechanical stress, we developed in vitro methods for preclinical biological material testings. The aim of the study was to evaluate the influence of revitalization of xenogenous scaffolds on biomechanical stability of tissue-engineered vessels. For measurement of radial distensibility, a salt-solution inflation method was used. The longitudinal tensile strength test (DIN 50145) was applied on bone-shaped specimen: tensile/tear strength (SigmaB/R), elongation at maximum yield stress/rupture (DeltaB/R), and modulus of elasticity were determined of native (NAs; n = 6), decellularized (DAs; n = 6), and decellularized carotid arteries reseeded with human vascular smooth muscle cells and human vascular endothelial cells (RAs; n = 7). Radial distensibility of DAs was significantly lower (113%) than for NAs (135%) (P < 0.001) or RAs (127%) (P = 0.018). At levels of 120 mm Hg and more, decellularized matrices burst (120, 160 [n = 2] and 200 mm Hg). Although RAs withstood levels up to 300 mm Hg, ANOVA revealed a significant difference from NA (P = 0.018). Compared with native vessels (NAs), SigmaB/R values were lower in DAs (44%; 57%) (P = 0.014 and P = 0.002, respectively) and were significantly higher in RAs (71%; 83%) (both P < 0.001). Similarly, DeltaB/R values were much higher in DAs compared with NAs (94%; 88%) (P < 0.001) and RAs (87%; 103%) (P < 0.001), but equivalent in NAs and RAs. Modulus of elasticity (2.6/1.1/3.7 to 16.6 N/mm(2)) of NAs, DAs, RAs was comparable (P = 0.088). Using newly developed in vitro methods for small-caliber vascular graft testing, this study proved that revitalization of decellularized connective tissue scaffolds led to vascular graft stability able to withstand biomechanical stress mimicking the human circulation. This tissue engineering approach provides a sufficiently stable autologized graft. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Physical modelling in biomechanics.

PubMed Central

Koehl, M A R

2003-01-01

Physical models, like mathematical models, are useful tools in biomechanical research. Physical models enable investigators to explore parameter space in a way that is not possible using a comparative approach with living organisms: parameters can be varied one at a time to measure the performance consequences of each, while values and combinations not found in nature can be tested. Experiments using physical models in the laboratory or field can circumvent problems posed by uncooperative or endangered organisms. Physical models also permit some aspects of the biomechanical performance of extinct organisms to be measured. Use of properly scaled physical models allows detailed physical measurements to be made for organisms that are too small or fast to be easily studied directly. The process of physical modelling and the advantages and limitations of this approach are illustrated using examples from our research on hydrodynamic forces on sessile organisms, mechanics of hydraulic skeletons, food capture by zooplankton and odour interception by olfactory antennules. PMID:14561350

[Nasolabial muscle finite-element study and clinical application].

PubMed

Yin, Ningbei; Wu, Jiajun; Chen, Bo; Wang, Yongqian; Song, Tao; Ma, Hengyuan

2015-05-01

To investigate the nasolabial muscle anatomy and biomechanical characteristics. Micro-computed tomography scan was performed in 8 cases of spontaneous abortion fetus lip nasal specimens to construct a three-dimensional model. The nasolabial muscle structure was analyzed using Mimics software. The three-dimensional configuration model of nasolabial muscle was established based on local anatomy and tissue section, and compared with tissue section. Three dimensional finite element analysis was performed on lip nasal muscle related biomechanics and surface deformation in Application verification was carried out in 263 cases of microform cleft lip surgery. There was close relationship between nasolabial muscle. The nasolabial muscle tension system was constituted, based on which a new cleft lip repair surgery was designed and satisfied results were achieved. There is close relationship among nasolabial muscle in anatomy, histology and biomechanics. To obtain better effect, cleft lip repair should be performed on the basis of recovering muscle tension system.

Biomechanical Effects of Posterior Condylar Offset and Posterior Tibial Slope on Quadriceps Force and Joint Contact Forces in Posterior-Stabilized Total Knee Arthroplasty.

PubMed

Kang, Kyoung-Tak; Koh, Yong-Gon; Son, Juhyun; Kwon, Oh-Ryong; Lee, Jun-Sang; Kwon, Sae Kwang

2017-01-01

This study aimed to determine the biomechanical effect of the posterior condylar offset (PCO) and posterior tibial slope (PTS) in posterior-stabilized (PS) fixed-bearing total knee arthroplasty (TKA). We developed ±1, ±2, and ±3 mm PCO models in the posterior direction and -3°, 0°, 3°, and 6° PTS models using a previously validated FE model. The influence of changes in the PCO and PTS on the biomechanical effects under deep-knee-bend loading was investigated. The contact stress on the PE insert increased by 14% and decreased by 7% on average as the PCO increased and decreased, respectively, compared to the neutral position. In addition, the contact stress on post in PE insert increased by 18% on average as PTS increased from -3° to 6°. However, the contact stress on the patellar button decreased by 11% on average as PTS increased from -3° to 6° in all different PCO cases. The quadriceps force decreased by 14% as PTS increased from -3° to 6° in all PCO models. The same trend was found in patellar tendon force. Changes in PCO had adverse biomechanical effects whereas PTS increase had positive biomechanical effects. However, excessive PTS should be avoided to prevent knee instability and subsequent failure.

Lower Extremity Energy Absorption and Biomechanics During Landing, Part I: Sagittal-Plane Energy Absorption Analyses

PubMed Central

Norcross, Marc F.; Lewek, Michael D.; Padua, Darin A.; Shultz, Sandra J.; Weinhold, Paul S.; Blackburn, J. Troy

2013-01-01

Context: Eccentric muscle actions of the lower extremity absorb kinetic energy during landing. Greater total sagittal-plane energy absorption (EA) during the initial impact phase (INI) of landing has been associated with landing biomechanics considered high risk for anterior cruciate ligament (ACL) injury. We do not know whether groups with different INI EA magnitudes exhibit meaningful differences in ACL-related landing biomechanics and whether INI EA might be useful to identify ACL injury-risk potential. Objective: To compare biomechanical factors associated with noncontact ACL injury among sagittal-plane INI EA groups and to determine whether an association exists between sex and sagittal-plane INI EA group assignment to evaluate the face validity of using sagittal-plane INI EA to identify ACL injury risk. Design: Descriptive laboratory study. Setting: Research laboratory. Patients or Other Participants: A total of 82 (41 men, 41 women; age = 21.0 ± 2.4 years, height = 1.74 ± 0.10 m, mass = 70.3 ± 16.1 kg) healthy, physically active individuals volunteered. Intervention(s): We assessed landing biomechanics using an electromagnetic motion-capture system and force plate during a double-legged jump-landing task. Main Outcome Measure(s): Total INI EA was used to group participants into high, moderate, and low tertiles. Sagittal- and frontal-plane knee kinematics; peak vertical and posterior ground reaction forces (GRFs); anterior tibial shear force; and internal hip extension, knee extension, and knee varus moments were identified and compared across groups using 1-way analyses of variance. We used a χ2 analysis to compare male and female representation in the high and low groups. Results: The high group exhibited greater knee-extension moment and posterior GRFs than both the moderate (P < .05) and low (P < .05) groups and greater anterior tibial shear force than the low group (P < .05). No other group differences were noted. Women were not represented more than men in the high group (χ2 = 1.20, P = .27). Conclusions: Greater sagittal-plane INI EA likely indicates greater ACL loading, but it does not appear to influence frontal-plane biomechanics related to ACL injury. Women were not more likely than men to demonstrate greater INI EA, suggesting that quantification of sagittal-plane INI EA alone is not sufficient to infer ACL injury-risk potential. PMID:23944382

Lower extremity energy absorption and biomechanics during landing, part I: sagittal-plane energy absorption analyses.

PubMed

Norcross, Marc F; Lewek, Michael D; Padua, Darin A; Shultz, Sandra J; Weinhold, Paul S; Blackburn, J Troy

2013-01-01

Eccentric muscle actions of the lower extremity absorb kinetic energy during landing. Greater total sagittal-plane energy absorption (EA) during the initial impact phase (INI) of landing has been associated with landing biomechanics considered high risk for anterior cruciate ligament (ACL) injury. We do not know whether groups with different INI EA magnitudes exhibit meaningful differences in ACL-related landing biomechanics and whether INI EA might be useful to identify ACL injury-risk potential. To compare biomechanical factors associated with noncontact ACL injury among sagittal-plane INI EA groups and to determine whether an association exists between sex and sagittal-plane INI EA group assignment to evaluate the face validity of using sagittal-plane INI EA to identify ACL injury risk. Descriptive laboratory study. Research laboratory. A total of 82 (41 men, 41 women; age = 21.0 ± 2.4 years, height = 1.74 ± 0.10 m, mass = 70.3 ± 16.1 kg) healthy, physically active individuals volunteered. We assessed landing biomechanics using an electromagnetic motion-capture system and force plate during a double-legged jump-landing task. Total INI EA was used to group participants into high, moderate, and low tertiles. Sagittal- and frontal-plane knee kinematics; peak vertical and posterior ground reaction forces (GRFs); anterior tibial shear force; and internal hip extension, knee extension, and knee varus moments were identified and compared across groups using 1-way analyses of variance. We used a χ (2) analysis to compare male and female representation in the high and low groups. The high group exhibited greater knee-extension moment and posterior GRFs than both the moderate (P < .05) and low (P < .05) groups and greater anterior tibial shear force than the low group (P < .05). No other group differences were noted. Women were not represented more than men in the high group (χ(2) = 1.20, P = .27). Greater sagittal-plane INI EA likely indicates greater ACL loading, but it does not appear to influence frontal-plane biomechanics related to ACL injury. Women were not more likely than men to demonstrate greater INI EA, suggesting that quantification of sagittal-plane INI EA alone is not sufficient to infer ACL injury-risk potential.

Biomechanical pulping : a mill-scale evaluation

Treesearch

Masood Akhtar; Gary M. Scott; Ross E. Swaney; Mike J. Lentz; Eric G. Horn; Marguerite S. Sykes; Gary C. Myers

1999-01-01

Mechanical pulping process is electrical energy intensive and results in low paper strength. Biomechanical pulping, defined as the fungal treatment of lignocellulosic materials prior to mechanical pulping, has shown at least 30% savings in electrical energy consumption, and significant improvements in paper strength properties compared to the control at a laboratory...

Mechanical characterization of benign and malignant urothelial cells from voided urine

NASA Astrophysics Data System (ADS)

Shojaei-Baghini, Ehsan; Zheng, Yi; Jewett, Michael A. S.; Geddie, William B.; Sun, Yu

2013-03-01

This study investigates whether mechanical differences exist between benign and malignant urothelial cells in voided urine. The Young's modulus of individual cells was measured using the micropipette aspiration technique. Malignant urothelial cells showed significantly lower Young's modulus values compared to benign urothelial cells. The results indicate that Young's modulus as a biomechanical marker could possibly provide additional information to conventional urinary cytology. We hope that these preliminary results could evoke attention to mechanical characterization of urine cells and spark interest in the development of biomechanical approaches to enhance non-invasive urothelial carcinoma detection.

The effect of gender and fatigue on the biomechanics of bilateral landings from a jump: peak values.

PubMed

Pappas, Evangelos; Sheikhzadeh, Ali; Hagins, Marshall; Nordin, Margareta

2007-01-01

Female athletes are substantially more susceptible than males to suffer acute non-contact anterior cruciate ligament injury. A limited number of studies have identified possible biomechanical risk factors that differ between genders. The effect of fatigue on the biomechanics of landing has also been inadequately investigated. The objective of the study was to examine the effect of gender and fatigue on peak values of biomechanical variables during landing from a jump. Thirty-two recreational athletes performed bilateral drop jump landings from a 40 cm platform. Kinetic, kinematic and electromyographic data were collected before and after a functional fatigue protocol. Females landed with 9° greater peak knee valgus (p = 0.001) and 140% greater maximum vertical ground reaction forces (p = 0.003) normalized to body weight compared to males. Fatigue increased peak foot abduction by 1.7° (p = 0.042), peak rectus femoris activity by 27% (p = 0.018), and peak vertical ground reaction force (p = 0.038) by 20%. The results of the study suggest that landing with increased peak knee valgus and vertical ground reaction force may contribute to increased risk for knee injury in females. Fatigue caused significant but small changes on some biomechanical variables. Anterior cruciate ligament injury prevention programs should focus on implementing strategies to effectively teach females to control knee valgus and ground reaction force. Key pointsFemale athletes landed with increased knee valgus and VGRF which may predispose them to ACL injury.Fatigue elicited a similar response in male and female athletes.The effectiveness of sports injury prevention programs may improve by focusing on teaching females to land softer and with less knee valgus.

The effects of once-weekly teriparatide on hip structure and biomechanical properties assessed by CT.

PubMed

Ito, M; Oishi, R; Fukunaga, M; Sone, T; Sugimoto, T; Shiraki, M; Nishizawa, Y; Nakamura, T

2014-03-01

Once-weekly administration of 56.5 μg teriparatide improved cortical bone parameters and biomechanical parameters at the proximal femur by CT geometry analysis. The aim of this study was to evaluate the effects of weekly administration of teriparatide [human PTH (1-34)] on bone geometry, volumetric bone mineral density (vBMD), and parameters of bone strength at the proximal femur which were longitudinally investigated using computed tomography (CT). The subjects were a subgroup of a recent, randomly assigned, double-blind study (578 subjects) comparing the anti-fracture efficacy of a once-weekly subcutaneous injection of 56.5 μg teriparatide with placebo (TOWER trial). Sixty-six ambulatory postmenopausal women with osteoporosis were enrolled at 15 study sites having multi-detector row CT, and included women injected with teriparatide (n = 29, 74.2 ± 5.1 years) or with placebo (n = 37, 74.8 ± 5.3 years). CT data were obtained at baseline and follow-up scans were performed at 48 and 72 weeks. The data were analyzed to obtain cross-sectional densitometric, geometric, and biomechanical parameters including the section modulus (SM) and buckling ratio (BR) of the femoral neck, inter-trochanter, and femoral shaft. We found that once-weekly teriparatide increased cortical thickness/cross-sectional area (CSA) and total area, and improved biomechanical properties (i.e., decreasing BR) at the femoral neck and shaft. Teriparatide did not change the cortical perimeter. Our longitudinal analysis of proximal femur geometry by CT revealed that once-weekly administration of 56.5 μg teriparatide improved cortical bone parameters at the femoral neck and shaft and also improved biomechanical parameters.

The Effect of Gender and Fatigue on the Biomechanics of Bilateral Landings from a Jump: Peak Values

PubMed Central

Pappas, Evangelos; Sheikhzadeh, Ali; Hagins, Marshall; Nordin, Margareta

2007-01-01

Female athletes are substantially more susceptible than males to suffer acute non-contact anterior cruciate ligament injury. A limited number of studies have identified possible biomechanical risk factors that differ between genders. The effect of fatigue on the biomechanics of landing has also been inadequately investigated. The objective of the study was to examine the effect of gender and fatigue on peak values of biomechanical variables during landing from a jump. Thirty-two recreational athletes performed bilateral drop jump landings from a 40 cm platform. Kinetic, kinematic and electromyographic data were collected before and after a functional fatigue protocol. Females landed with 9° greater peak knee valgus (p = 0.001) and 140% greater maximum vertical ground reaction forces (p = 0.003) normalized to body weight compared to males. Fatigue increased peak foot abduction by 1.7° (p = 0.042), peak rectus femoris activity by 27% (p = 0.018), and peak vertical ground reaction force (p = 0.038) by 20%. The results of the study suggest that landing with increased peak knee valgus and vertical ground reaction force may contribute to increased risk for knee injury in females. Fatigue caused significant but small changes on some biomechanical variables. Anterior cruciate ligament injury prevention programs should focus on implementing strategies to effectively teach females to control knee valgus and ground reaction force. Key pointsFemale athletes landed with increased knee valgus and VGRF which may predispose them to ACL injury.Fatigue elicited a similar response in male and female athletes.The effectiveness of sports injury prevention programs may improve by focusing on teaching females to land softer and with less knee valgus. PMID:24149228

Comparative Biomechanical Behavior and Healing Profile of a Novel Thinned Wall Ultrahigh Molecular Weight Amorphous Poly-l-Lactic Acid Sirolimus-Eluting Bioresorbable Coronary Scaffold.

PubMed

Cheng, Yanping; Gasior, Pawel; Xia, Jing-Gang; Ramzipoor, Kamal; Lee, Chang; Estrada, Edward A; Dokko, Daniell; McGregor, Jenn C; Conditt, Gerard B; McAndrew, Thomas; Kaluza, Greg L; Granada, Juan F

2017-07-01

Mechanical strength of bioresorbable scaffolds (BRS) is highly dependent on strut dimensions and polymer features. To date, the successful development of thin-walled BRS has been challenging. We compared the biomechanical behavior and vascular healing profile of a novel thin-walled (115 µm) sirolimus-eluting ultrahigh molecular weight amorphous poly-l-lactic acid-based BRS (APTITUDE, Amaranth Medical [AMA]) to Absorb (bioresorbable vascular scaffold [BVS]) using different experimental models. In vitro biomechanical testing showed no fractures in the AMA-BRS when overexpanded 1.3 mm above nominal dilatation values (≈48%) and lower number of fractures on accelerated cycle testing over time (at 21 K cycles=20.0 [19.5-20.5] in BVS versus 4.0 [3.0-4.3] in AMA-BRS). In the healing response study, 35 AMA-BRS and 23 BVS were implanted in 58 coronary arteries of 23 swine and followed-up to 180 days. Scaffold strut healing was evaluated in vivo using weekly optical coherence tomography analysis. At 14 days, the AMA-BRS demonstrated a higher percentage of embedded struts (71.0% [47.6, 89.1] compared with BVS 40.3% [20.5, 63.2]; P =0.01). At 21 days, uncovered struts were still present in the BVS group (3.8% [2.1, 10.2]). Histopathology revealed lower area stenosis (AMA-BRS, 21.0±6.1% versus BVS 31.0±4.5%; P =0.002) in the AMA-BRS at 28 days. Neointimal thickness and inflammatory scores were comparable between both devices at 180 days. A new generation thinned wall BRS displayed a more favorable biomechanical behavior and strut healing profile compared with BVS in normal porcine coronary arteries. This novel BRS concept has the potential to improve the clinical outcomes of current generation BRS. © 2017 American Heart Association, Inc.

Biomechanical Analysis of the Efficacy of Locking Plates during Cyclic Loading in Metacarpal Fractures

PubMed Central

Meffert, Rainer H.; Raschke, Michael J.; Blunk, Torsten; Ochman, Sabine

2014-01-01

Purpose. To analyse the biomechanical characteristics of locking plates under cyclic loading compared to a nonlocking plate in a diaphyseal metacarpal fracture. Methods. Oblique diaphyseal shaft fractures in porcine metacarpal bones were created in a biomechanical fracture model. An anatomical reduction and stabilization with a nonlocking and a comparable locking plate in mono- or bicortical screw fixation followed. Under cyclic loading, the displacement, and in subsequent load-to-failure tests, the maximum load and stiffness were measured. Results. For the monocortical screw fixation of the locking plate, a similar displacement, maximum load, and stiffness could be demonstrated compared to the bicortical screw fixation of the nonlocking plate. Conclusions. Locking plates in monocortical configuration may function as a useful alternative to the currently common treatment with bicortical fixations. Thereby, irritation of the flexor tendons would be avoided without compromising the stability, thus enabling the necessary early functional rehabilitation. PMID:24757429

Convergence and stress analysis of the homogeneous structure of human femur bone during standing up condition

NASA Astrophysics Data System (ADS)

Izzawati, B.; Daud, R.; Afendi, M.; Majid, M. S. Abdul; Zain, N. A. M.

2017-09-01

Finite element models have been widely used to quantify the stress analysis and to predict the bone fractures of the human body. The present study highlights on the stress analysis of the homogeneous structure of human femur bone during standing up condition. The main objective of this study is to evaluate and understand the biomechanics for human femur bone and to prepare orthotropic homogeneous material models used for FE analysis of the global proximal femur. Thus, it is necessary to investigate critical stress on the human femur bone for future study on implantation of internal fixator and external fixator. The implication possibility to create a valid FE model by simply comparing the FE results with the actual biomechanics structures. Thus, a convergence test was performed by FE model of the femur and the stress analysis based on the actual biomechanics of the human femur bone. An increment of critical stress shows in the femur shaft as the increasing of load on the femoral head and decreasing the pulling force at greater trochanter.

Strength of suture anchor versus transosseous tunnel in anatomic reconstruction of the ankle lateral ligaments: a biomechanical study.

PubMed

Li, Hong-Yun; Hua, Ying-Hui; Wu, Zi-Ying; Chen, Bo; Chen, Shi-Yi

2013-11-01

The purpose of this study was to compare the biomechanical characteristics of fixation with 2-suture anchors versus transosseous tunnel fixation in anatomic reconstruction of the ankle lateral ligaments. Six matched pairs of human cadaveric ankles underwent anatomic lateral ankle reconstruction, and fixation of the graft on the talus was achieved with 2 suture anchors or a transosseous tunnel. Ankles for the transosseous tunnel group were chosen at random, with the paired contralateral ankles used for the 2-suture anchor group. Half of the peroneus brevis tendon was harvested as a graft. For each technique, one end of the tendon was secured to the original insertion point of the anterior talofibular ligament (ATFL) at the talus, whereas the other end was armed with 2 No. 5 nonabsorbable sutures (Ethicon, Somerville, NJ) and passed through the bone tunnel in the fibula. Biomechanical testing was performed by applying the force in line with the graft. Load to failure was determined at a displacement rate of 50 mm/min. The load-displacement curve, maximum load at failure (N), and stiffness (N/mm) were recorded and compared between the 2 techniques. There was no difference between constructs in the 2-suture anchor group and the transosseous tunnel group in terms of the ultimate load and stiffness (161.8 ± 47.6 N v 171.9 ± 76.0 N; P = .92; 4.59 ± 1.85 N/mm v 5.77 ± 1.98 N/mm; P = .35). Most constructs failed because of anchor pullout in the 2-suture anchor group (5 of 6) and fracture of the bony bridge in the transosseous tunnel group (6 of 6). The strength of fixation with suture anchors in anatomic reconstruction of the ankle lateral ligaments was equivalent to transosseous tunnel fixation as determined with biomechanical testing. However, this study did not prove that one is advantageous over the other. Both techniques showed excellent biomechanical results. Therefore, the 2-suture anchor fixation approach can be safely used in anatomic reconstruction of the ankle lateral ligaments. Copyright © 2013 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Medial malleolar fractures: a biomechanical study of fixation techniques.

PubMed

Fowler, T Ty; Pugh, Kevin J; Litsky, Alan S; Taylor, Benjamin C; French, Bruce G

2011-08-08

Fracture fixation of the medial malleolus in rotationally unstable ankle fractures typically results in healing with current fixation methods. However, when failure occurs, pullout of the screws from tension, compression, and rotational forces is predictable. We sought to biomechanically test a relatively new technique of bicortical screw fixation for medial malleoli fractures. Also, the AO group recommends tension-band fixation of small avulsion type fractures of the medial malleolus that are unacceptable for screw fixation. A well-documented complication of this technique is prominent symptomatic implants and secondary surgery for implant removal. Replacing stainless steel 18-gauge wire with FiberWire suture could theoretically decrease symptomatic implants. Therefore, a second goal was to biomechanically compare these 2 tension-band constructs. Using a tibial Sawbones model, 2 bicortical screws were compared with 2 unicortical cancellous screws on a servohydraulic test frame in offset axial, transverse, and tension loading. Second, tension-band fixation using stainless steel wire was compared with FiberWire under tensile loads. Bicortical screw fixation was statistically the stiffest construct under tension loading conditions compared to unicortical screw fixation and tension-band techniques with FiberWire or stainless steel wire. In fact, unicortical screw fixation had only 10% of the stiffness as demonstrated in the bicortical technique. In a direct comparison, tension-band fixation using stainless steel wire was statistically stiffer than the FiberWire construct. Copyright 2011, SLACK Incorporated.

Biomechanical adaptations of mice cortical bone submitted to three different exercise modalities

PubMed Central

Frajacomo, Fernando Tadeu Trevisan; Falcai, Maurício José; Fernandes, Cleverson Rodrigues; Shimano, Antonio Carlos; Garcia, Sérgio Britto

2013-01-01

Objective To compare the adaptive effects of three non-weight bearing exercise on bone mechanical properties. Methods 24 male Balb/c mice (22-25g), were randomly divided into four groups (n=6): sedentary group (S); swimming group (N) which performed sessions five times per week for 60 min progressively; resistance group (R), which performed climbing exercise with progressive load, three times per week; and combined group (C), which performed the same protocols aforementioned being three times a week according to N protocol and two times a week the R protocol during eight weeks. Biomechanical tests, load until failure and stiffness evaluation of shinbone was performed after animals have been sacrificed. Results Stiffness values were statistically higher only in the isolated modalities groups (N and R, 41.68 ± 10.43 and 41.21 ± 11.38 N/mm, respectively) compared with the S group (28.48 ± 7.34 N/mm). However, taking into consideration the final body mass, relative values, there was no difference in the biomechanical tests among the groups. Conclusion Data from the present investigation demonstrated a favorable influence of muscle contraction in lower impact isolated exercise modalities on absolute stiffness values, i.e.groups N and R, whereas the combined group (C) did not present any statistical significant difference compared to sedentary group. Level of Evidence II, Prospective Comparative Study. PMID:24453691

Conceptual finite element study for comparison among superior, anterior, and spiral clavicle plate fixations for midshaft clavicle fracture.

PubMed

Huang, Teng-Le; Chen, Wen-Chuan; Lin, Kun-Jhih; Tsai, Cheng-Lun; Lin, Kang-Ping; Wei, Hung-Wen

2016-10-01

Open reduction internal fixation technique has been generally accepted for treatment of midshaft clavicle fractures. Both superior and anterior clavicle plates have been reported in clinical or biomechanical researches, while presently the spiral clavicle plate design has been introduced improved biomechanical behavior over conventional designs. In order to objectively realize the multi-directional biomechanical performances among the three geometries for clavicle plate designs, a current conceptual finite element study has been conducted with identical cross-sectional features for clavicle plates. The conceptual superior, anterior, and spiral clavicle plate models were constructed for virtual reduction and fixation to an OTA 15-B1.3 midshaft transverse fracture of clavicle. Mechanical load cases including cantilever bending, axial compression, inferior bending, and axial torsion have been applied for confirming the multi-directional structural stability and implant safety in biomechanical perspective. Results revealed that the anterior clavicle plate model represented lowest plate stress under all loading cases. The superior clavicle plate model showed greater axial compressive stiffness, while the anterior clavicle plate model performed greater rigidity under cantilever bending load. Three model represented similar structural stiffness under axial torsion. Played as a transition structure between superior and anterior clavicle plate, the spiral clavicle plate model revealed comparable results with acceptable multi-directional biomechanical behavior. The concept of spiral clavicle plate design is worth considering in practical application in clinics. Implant safety should be further investigated by evidences in future mechanical tests and clinical observations. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

The effect of pharmacological treatment on gait biomechanics in peripheral arterial disease patients

PubMed Central

2010-01-01

Background Pharmacological treatment has been advocated as a first line therapy for Peripheral Arterial Disease (PAD) patients suffering from intermittent claudication. Previous studies document the ability of pharmacological treatment to increase walking distances. However, the effect of pharmacological treatment on gait biomechanics in PAD patients has not been objectively evaluated as is common with other gait abnormalities. Methods Sixteen patients were prescribed an FDA approved drug (Pentoxifylline or Cilostazol) for the treatment of symptomatic PAD. Patients underwent baseline gait testing prior to medication use which consisted of acquisition of ground reaction forces and kinematics while walking in a pain free state. After three months of treatment, patients underwent repeat gait testing. Results Patients with symptomatic PAD had significant gait abnormalities at baseline during pain free walking as compared to healthy controls. However, pharmacological treatment did not produce any identifiable alterations on the biomechanics of gait of the PAD patients as revealed by the statistical comparisons performed between pre and post-treatment and between post-treatment and the healthy controls. Conclusions Pharmacological treatment did not result in statistically significant improvements in the gait biomechanics of patients with symptomatic PAD. Future studies will need to further explore different cohorts of patients that have shown to improve significantly their claudication distances and/or their muscle fiber morphology with the use of pharmacological treatment and determine if this is associated with an improvement in gait biomechanics. Using these methods we may distinguish the patients who benefit from pharmacotherapy and those who do not. PMID:20529284

Biomechanical consequences of subtalar joint arthroereisis in treating posterior tibial tendon dysfunction: a theoretical analysis using finite element analysis.

PubMed

Wong, Duo Wai-Chi; Wang, Yan; Chen, Tony Lin-Wei; Leung, Aaron Kam-Lun; Zhang, Ming

2017-11-01

Subtalar joint arthroereisis (SJA) has been introduced to control the hyperpronation in cases of flatfoot. The objective of this study is to evaluate the biomechanical consequence of SJA to restore the internal stress and load transfer to the intact state from the attenuated biomechanical condition induced by posterior tibial tendon dysfunction (PTTD). A three-dimensional finite element model of the foot and ankle complex was constructed based on clinical images of a healthy female (age 28 years, height 165 cm, body mass 54 kg). The boundary and loading condition during walking was acquired from the gait experiment of the model subject. Five sets of simulations (conditions) were completed: intact condition, mild PTTD, severe PTTD, mild PTTD with SJA, severe PTTD with SJA. The maximum von Mises stress of the metatarsal shafts and the load transfer along the midfoot during stance were analyzed. Generally, SJA deteriorated the joint force of the medial cuneonavicular and calcaneocuboid joints during late stance, while that of the metatarsocuneiform joints during early stance were over-corrected. Only the calcaneocuboid joint force at 45% stance demonstrated a trend of improvement. Besides, SJA exaggerated the increased stress of the metatarsals compared to the PTTD conditions, except that of the first metatarsal. Our study did not support the hypothesis that SJA can restore the internal load transfer and midfoot stress. SJA cannot compensate the salvage of midfoot stability attributed by PTTD and could be biomechanically insufficient to restore the biomechanical environment. Additional procedures such as orthotic intervention may be necessary.

Lower extremity energy absorption and biomechanics during landing, part II: frontal-plane energy analyses and interplanar relationships.

PubMed

Norcross, Marc F; Lewek, Michael D; Padua, Darin A; Shultz, Sandra J; Weinhold, Paul S; Blackburn, J Troy

2013-01-01

Greater sagittal-plane energy absorption (EA) during the initial impact phase (INI) of landing is consistent with sagittal-plane biomechanics that likely increase anterior cruciate ligament (ACL) loading, but it does not appear to influence frontal-plane biomechanics. We do not know whether frontal-plane INI EA is related to high-risk frontal-plane biomechanics. To compare biomechanics among INI EA groups, determine if women are represented more in the high group, and evaluate interplanar INI EA relationships. Descriptive laboratory study. Research laboratory. Participants included 82 (41 men, 41 women; age = 21.0 ± 2.4 years, height = 1.74 ± 0.10 m, mass = 70.3 ± 16.1 kg) healthy, physically active volunteers. We assessed landing biomechanics with an electromagnetic motion-capture system and force plate. We calculated frontal- and sagittal-plane total, hip, knee, and ankle INI EA. Total frontal-plane INI EA was used to create high, moderate, and low tertiles. Frontal-plane knee and hip kinematics, peak vertical and posterior ground reaction forces, and peak internal knee-varus moment (pKVM) were identified and compared across groups using 1-way analyses of variance. We used a χ (2) analysis to evaluate male and female allocation to INI EA groups. We used simple, bivariate Pearson product moment correlations to assess interplanar INI EA relationships. The high-INI EA group exhibited greater knee valgus at ground contact, hip adduction at pKVM, and peak hip adduction than the low-INI EA group (P < .05) and greater peak knee valgus, pKVM, and knee valgus at pKVM than the moderate- (P < .05) and low- (P < .05) INI EA groups. Women were more likely than men to be in the high-INI EA group (χ(2) = 4.909, P = .03). Sagittal-plane knee and frontal-plane hip INI EA (r = 0.301, P = .006) and sagittal-plane and frontal-plane ankle INI EA were associated (r = 0.224, P = .04). No other interplanar INI EA relationships were found (P > .05). Greater frontal-plane INI EA was associated with less favorable frontal-plane biomechanics that likely result in greater ACL loading. Women were more likely than men to use greater frontal-plane INI EA. The magnitudes of sagittal- and frontal-plane INI EA were largely independent.

A literature review of the effects of computer input device design on biomechanical loading and musculoskeletal outcomes during computer work.

PubMed

Bruno Garza, J L; Young, J G

2015-01-01

Extended use of conventional computer input devices is associated with negative musculoskeletal outcomes. While many alternative designs have been proposed, it is unclear whether these devices reduce biomechanical loading and musculoskeletal outcomes. To review studies describing and evaluating the biomechanical loading and musculoskeletal outcomes associated with conventional and alternative input devices. Included studies evaluated biomechanical loading and/or musculoskeletal outcomes of users' distal or proximal upper extremity regions associated with the operation of alternative input devices (pointing devices, mice, other devices) that could be used in a desktop personal computing environment during typical office work. Some alternative pointing device designs (e.g. rollerbar) were consistently associated with decreased biomechanical loading while other designs had inconsistent results across studies. Most alternative keyboards evaluated in the literature reduce biomechanical loading and musculoskeletal outcomes. Studies of other input devices (e.g. touchscreen and gestural controls) were rare, however, those reported to date indicate that these devices are currently unsuitable as replacements for traditional devices. Alternative input devices that reduce biomechanical loading may make better choices for preventing or alleviating musculoskeletal outcomes during computer use, however, it is unclear whether many existing designs are effective.

Biomechanics, Exercise Physiology, and the 75th Anniversary of RQES

ERIC Educational Resources Information Center

Hamill, Joseph; Haymes, Emily M.

2005-01-01

The purpose of this paper is to review the biomechanics and exercise physiology studies published in the Research Quarterly for Exercise and Sport (RQES) over the past 75 years. Studies in biomechanics, a relatively new subdiscipline that evolved from kinesiology, first appeared in the journal about 40 years ago. Exercise physiology studies have…

Speciation through the lens of biomechanics: locomotion, prey capture and reproductive isolation.

PubMed

Higham, Timothy E; Rogers, Sean M; Langerhans, R Brian; Jamniczky, Heather A; Lauder, George V; Stewart, William J; Martin, Christopher H; Reznick, David N

2016-09-14

Speciation is a multifaceted process that involves numerous aspects of the biological sciences and occurs for multiple reasons. Ecology plays a major role, including both abiotic and biotic factors. Whether populations experience similar or divergent ecological environments, they often adapt to local conditions through divergence in biomechanical traits. We investigate the role of biomechanics in speciation using fish predator-prey interactions, a primary driver of fitness for both predators and prey. We highlight specific groups of fishes, or specific species, that have been particularly valuable for understanding these dynamic interactions and offer the best opportunities for future studies that link genetic architecture to biomechanics and reproductive isolation (RI). In addition to emphasizing the key biomechanical techniques that will be instrumental, we also propose that the movement towards linking biomechanics and speciation will include (i) establishing the genetic basis of biomechanical traits, (ii) testing whether similar and divergent selection lead to biomechanical divergence, and (iii) testing whether/how biomechanical traits affect RI. Future investigations that examine speciation through the lens of biomechanics will propel our understanding of this key process. © 2016 The Author(s).

Speciation through the lens of biomechanics: locomotion, prey capture and reproductive isolation

PubMed Central

Rogers, Sean M.; Langerhans, R. Brian; Jamniczky, Heather A.; Lauder, George V.; Stewart, William J.; Martin, Christopher H.; Reznick, David N.

2016-01-01

Speciation is a multifaceted process that involves numerous aspects of the biological sciences and occurs for multiple reasons. Ecology plays a major role, including both abiotic and biotic factors. Whether populations experience similar or divergent ecological environments, they often adapt to local conditions through divergence in biomechanical traits. We investigate the role of biomechanics in speciation using fish predator–prey interactions, a primary driver of fitness for both predators and prey. We highlight specific groups of fishes, or specific species, that have been particularly valuable for understanding these dynamic interactions and offer the best opportunities for future studies that link genetic architecture to biomechanics and reproductive isolation (RI). In addition to emphasizing the key biomechanical techniques that will be instrumental, we also propose that the movement towards linking biomechanics and speciation will include (i) establishing the genetic basis of biomechanical traits, (ii) testing whether similar and divergent selection lead to biomechanical divergence, and (iii) testing whether/how biomechanical traits affect RI. Future investigations that examine speciation through the lens of biomechanics will propel our understanding of this key process. PMID:27629033

What is the definition of sports-related concussion: a systematic review.

PubMed

McCrory, Paul; Feddermann-Demont, Nina; Dvořák, Jiří; Cassidy, J David; McIntosh, Andrew; Vos, Pieter E; Echemendia, Ruben J; Meeuwisse, Willem; Tarnutzer, Alexander A

2017-06-01

Various definitions for concussion have been proposed, each having its strengths and weaknesses. We reviewed and compared current definitions and identified criteria necessary for an operational definition of sports-related concussion (SRC) in preparation of the 5th Concussion Consensus Conference (Berlin, Germany). We also assessed the role of biomechanical studies in informing an operational definition of SRC. This is a systematic literature review. Data sources include MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature, Cochrane Central Register of Clinical Trials and SPORT Discus (accessed 14 September 2016). Eligibility criteria were studies reporting (clinical) criteria for diagnosing SRC and studies containing SRC impact data. Out of 1601 articles screened, 36 studies were included (2.2%), 14 reported on criteria for SRC definitions and 22 on biomechanical aspects of concussions. Six different operational definitions focusing on clinical findings and their dynamics were identified. Biomechanical studies were obtained almost exclusively on American football players. Angular and linear head accelerations linked to clinically confirmed concussions demonstrated considerable individual variation. SRC is a traumatic brain injury that is defined as a complex pathophysiological process affecting the brain, induced by biomechanical forces with several common features that help define its nature. Limitations identified include that the current criteria for diagnosing SRC are clinically oriented and that there is no gold/standard to assess their diagnostic properties. A future, more valid definition of SRC would better identify concussed players by demonstrating high predictive positive/negative values. Currently, the use of helmet-based systems to study the biomechanics of SRC is limited to few collision sports. New approaches need to be developed to provide objective markers for SRC. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Biomechanics of penetrating trauma.

PubMed

Yoganandan, N; Pintar, F A

1997-01-01

It is well known that injuries and deaths due to penetrating projectiles have become a national and an international epidemic in Western society. The application of biomedical engineering to solve day-to-day problems has produced considerable advances in safety and mitigation/prevention of trauma. The study of penetrating trauma has been largely in the military domain where war-time specific applications were advanced with the use of high-velocity weapons. With the velocity and weapon caliber in the civilian population at half or less compared with the military counterpart, wound ballistics is a largely different problem in today's trauma centers. The principal goal of the study of penetrating injuries in the civilian population is secondary prevention and optimized emergency care after occurrence. A thorough understanding of the dynamic biomechanics of penetrating injuries quantifies missile type, caliber, and velocity to hard and soft tissue damage. Such information leads to a comprehensive assessment of the acute and long-term treatment of patients with penetrating injuries. A review of the relevant military research applied to the civilian domain and presentation of new technology in the biomechanical study of these injuries offer foundation to this field. Relevant issues addressed in this review article include introduction of the military literature, the need for secondary prevention, environmental factors including projectile velocity and design, experimental studies with biological tissues and physical models, and mathematical simulations and analyses. Areas of advancement are identified that enables the pursuit of biomechanics research in order to arrive at better secondary prevention strategies.

Artificial Intelligence in Sports Biomechanics: New Dawn or False Hope?

PubMed Central

Bartlett, Roger

2006-01-01

This article reviews developments in the use of Artificial Intelligence (AI) in sports biomechanics over the last decade. It outlines possible uses of Expert Systems as diagnostic tools for evaluating faults in sports movements (‘techniques’) and presents some example knowledge rules for such an expert system. It then compares the analysis of sports techniques, in which Expert Systems have found little place to date, with gait analysis, in which they are routinely used. Consideration is then given to the use of Artificial Neural Networks (ANNs) in sports biomechanics, focusing on Kohonen self-organizing maps, which have been the most widely used in technique analysis, and multi-layer networks, which have been far more widely used in biomechanics in general. Examples of the use of ANNs in sports biomechanics are presented for javelin and discus throwing, shot putting and football kicking. I also present an example of the use of Evolutionary Computation in movement optimization in the soccer throw in, which predicted an optimal technique close to that in the coaching literature. After briefly overviewing the use of AI in both sports science and biomechanics in general, the article concludes with some speculations about future uses of AI in sports biomechanics. Key Points Expert Systems remain almost unused in sports biomechanics, unlike in the similar discipline of gait analysis. Artificial Neural Networks, particularly Kohonen Maps, have been used, although their full value remains unclear. Other AI applications, including Evolutionary Computation, have received little attention. PMID:24357939

Artificial intelligence in sports biomechanics: new dawn or false hope?

PubMed

Bartlett, Roger

2006-12-15

This article reviews developments in the use of Artificial Intelligence (AI) in sports biomechanics over the last decade. It outlines possible uses of Expert Systems as diagnostic tools for evaluating faults in sports movements ('techniques') and presents some example knowledge rules for such an expert system. It then compares the analysis of sports techniques, in which Expert Systems have found little place to date, with gait analysis, in which they are routinely used. Consideration is then given to the use of Artificial Neural Networks (ANNs) in sports biomechanics, focusing on Kohonen self-organizing maps, which have been the most widely used in technique analysis, and multi-layer networks, which have been far more widely used in biomechanics in general. Examples of the use of ANNs in sports biomechanics are presented for javelin and discus throwing, shot putting and football kicking. I also present an example of the use of Evolutionary Computation in movement optimization in the soccer throw in, which predicted an optimal technique close to that in the coaching literature. After briefly overviewing the use of AI in both sports science and biomechanics in general, the article concludes with some speculations about future uses of AI in sports biomechanics. Key PointsExpert Systems remain almost unused in sports biomechanics, unlike in the similar discipline of gait analysis.Artificial Neural Networks, particularly Kohonen Maps, have been used, although their full value remains unclear.Other AI applications, including Evolutionary Computation, have received little attention.

A novel fixation system for sacroiliac dislocation fracture: internal fixation system design and biomechanics analysis.

PubMed

Dawei, Tian; Na, Liu; Jun, Lei; Wei, Jin; Lin, Cai

2013-02-01

Although there were many different types of fixation techniques for sacroiliac dislocation fracture, the treat remained challenging in posterior pelvic ring injury. The purpose of this study was to evaluate the biomechanical effects of a novel fixation system we designed. 12 human cadavers (L3-pelvic-femora) were used to compare biomechanical stability after reconstruction on the same specimens in four conditions: (1) intact, (2) cable system, (3) plate-pedicle screw system, and (4) cable system and plate-pedicle screw combination system (combination system). Biomechanical testing was performed on a material testing machine for evaluating the stiffness of the pelvic fixation construct in compression and torsion. The cable system and plate-pedicle screw system alone may be insufficient to resist vertical shearing and rotational loads; however the combination system for unstable sacroiliac dislocation fractures provided significantly greater stability than single plate-pedicle or cable fixation system. The novel fixation system for unstable sacroiliac dislocation fractures produced sufficient stability in axial compression and axial rotation test in type C pelvic ring injuries. It may also offer a better solution for sacroiliac dislocation fractures. Copyright © 2012 Elsevier Ltd. All rights reserved.

Cross-Linking Biomechanical Effect in Human Corneas by Same Energy, Different UV-A Fluence: An Enzymatic Digestion Comparative Evaluation.

PubMed

Kanellopoulos, Anastasios J; Loukas, Yannis L; Asimellis, George

2016-04-01

To evaluate ex vivo the possible difference in corneal cross-linking (CXL) biomechanical effect of different ultraviolet-A (UV-A) irradiances. The study involved 25 human donor corneas, randomly allocated to 5 groups (n = 5 each). CXL was applied with UV-A irradiances of 3, 9, 18, 30, and 45 mW/cm2, maintaining equal cumulative energy dose of 5.4 J/cm2. UV-A was delivered on half of the cornea. The nonirradiated halves served as controls. Specimens were subjected to collagenase-A enzymatic digestion. The time to complete dissolution in each specimen was recorded. Time to dissolution in group-A (3 mW/cm2 for 30 minutes) was 321 ± 13.4 minutes (range: 300-330) compared with 171 ± 8.2 (range: 165-180) for their control. In group-B (9 mW/cm2 for 10 minutes), it was 282 ± 19.6 minutes (range: 270-315) compared with 177 ± 6.7 (165-180) for their control. In group-C (18 mW/cm2 for 5 minutes), it was 267 ± 19.6 minutes (range: 240-285) compared with 177 ± 7.7 (range: 165-180) for their control. In group-D (30 mW/cm2 for 3 minutes), it was 252 ± 12.5 minutes (range: 240-270) compared with 180 ± 10.6 minutes (range: 165-195) for their control. In group-E (45 mW/cm2 for 2 minutes), it was 204 ± 17.1 minutes (range: 180-225) compared with 186 ± 8.2 minutes (range: 180-195) for their control. The data in this ex vivo human corneal study indicate that the biomechanical effect of CXL studied by resistance to enzymatic digestion in human corneas is comparable between irradiances of 9, 18 and 30 mW/cm and seems to be reduced at a fluence of 45 mW/cm2.

A modified and enhanced test setup for biomechanical investigations of the hindfoot, for example in tibiotalocalcaneal arthrodesis.

PubMed

Evers, Julia; Schulze, Martin; Gehweiler, Dominic; Lakemeier, Martin; Raschke, Michael J; Wähnert, Dirk; Ochman, Sabine

2016-07-29

Tibiotalocalcaneal arthrodesis (TTCA) using intramedullary nails is a salvage procedure for many diseases in the ankle and subtalar joint. Despite "newly described intramedullary nails" with specific anatomical shapes there still remain major complications regarding this procedure. The following study presents a modified biomechanical test setup for investigations of the hindfoot. Nine fresh-frozen specimens from below the human knee were anaysed using the Hindfoot Arthrodesis Nail (Synthes) instrument. Quasi-static biomechanical testing was performed for internal/external rotation, varus/valgus and dorsal/plantar flexion using a modified established setup (physiological load entrance point, sledge at lever arm to apply pure moments). Additionally, a 3D optical measurement system was added to allow determination of interbony movements. The mean torsional range of motion (ROM) calculated from the actuator data of a material testing machine was 10.12° (SD 0.6) compared to 10° (SD 2.83) as measured with the Optotrak® system (between tibia and calcaneus). The Optotrak showed 40 % more rotation in the talocrural joint. Mean varus/valgus ROM from the material testing flexion machine was seen to be 5.65° (SD 1.84) in comparison to 2.82° (SD 0.46) measured with the Optotrak. The subtalar joint showed a 70 % higher movement when compared to the talocrural joint. Mean ROM in the flexion test was 5.3° (SD 1.45) for the material testing machine and 2.1° (SD 0.39) for the Optotrak. The movement in the talocrural joint was 3 times higher compared to the subtalar joint. The modified test setup presented here for the hindfoot allows a physiological biomechanical loading. Moreover, a detailed characterisation of the bone-implant constructs is possible.

Shoulder Kinematics and Spatial Pattern of Trapezius Electromyographic Activity in Real and Virtual Environments

PubMed Central

Samani, Afshin; Pontonnier, Charles; Dumont, Georges; Madeleine, Pascal

2015-01-01

The design of an industrial workstation tends to include ergonomic assessment steps based on a digital mock-up and a virtual reality setup. Lack of interaction and system fidelity is often reported as a main issue in such virtual reality applications. This limitation is a crucial issue as thorough ergonomic analysis is required for an investigation of the biomechanics. In the current study, we investigated the biomechanical responses of the shoulder joint in a simulated assembly task for comparison with the biomechanical responses in virtual environments. Sixteen male healthy novice subjects performed the task on three different platforms: real (RE), virtual (VE), and virtual environment with force feedback (VEF) with low and high precision demands. The subjects repeated the task 12 times (i.e., 12 cycles). High density electromyography from the upper trapezius and rotation angles of the shoulder joint were recorded and split into the cycles. The angular trajectories and velocity profiles of the shoulder joint angles over a cycle were computed in 3D. The inter-subject similarity in terms of normalized mutual information on kinematics and electromyography was investigated. Compared with RE the task in VE and VEF was characterized by lower kinematic maxima. The inter-subject similarity in RE compared with intra-subject similarity across the platforms was lower in terms of movement trajectories and greater in terms of trapezius muscle activation. The precision demand resulted in lower inter- and intra-subject similarity across platforms. The proposed approach identifies biomechanical differences in the shoulder joint in both VE and VEF compared with the RE platform, but these differences are less marked in VE mostly due to technical limitations of co-localizing the force feedback system in the VEF platform. PMID:25768123

Effects of menarcheal age on the anterior cruciate ligament injury risk factors during single-legged drop landing in female artistic elite gymnasts.

PubMed

Kim, Kew-Wan; Lim, Bee-Oh

2014-11-01

Although numerous studies have demonstrated the relationship between maturation and lower extremity biomechanics during landing in team sport athletes, we are presently uninformed of any research that examined the single-legged drop landing biomechanics of gymnasts. The purpose of this study is to investigate the effects of the menarcheal age on the lower extremity biomechanics during a single-legged drop landing in female artistic elite gymnasts. Twenty-two female artistic elite gymnasts, between 9 and 36 years of age, participated in this study. The participants were divided into two groups pre- (n = 11) and post- (n = 11) menarche and asked to perform a single-legged drop landing on top of a 30 cm platform and land on a force plate. The statistical analysis consisted of the multivariate analysis with the level of significance set at p < 0.05. The post-menarche group showed a decrease in their maximum knee flexion angle and increase in their maximum knee abduction angle, maximum internal tibial rotation angle, maximum knee abduction moment, and hamstring-quadriceps muscle activity ratio compared with the pre-menarche group during the single-legged drop landing. The post-menarche group showed an increased noncontact anterior cruciate ligament injury risk, due to their greater knee loads, compared with the pre-menarche group.

Biomechanical properties of jaw periosteum-derived mineralized culture on different titanium topography.

PubMed

Att, Wael; Kubo, Katsutoshi; Yamada, Masahiro; Maeda, Hatsuhiko; Ogawa, Takahiro

2009-01-01

This study evaluated the biomechanical properties of periosteum-derived mineralized culture on different surface topographies of titanium. Titanium surfaces modified by machining or by acid etching were analyzed using scanning electron microscopy (SEM). Rat mandibular periosteum-derived cells were cultured on either of the titanium surfaces. Cell proliferation was evaluated by cell counts, and gene expression was analyzed using a reverse-transcriptase polymerase chain reaction. Alkaline phosphatase (ALP) stain assay was employed to evaluate osteoblastic activity. Matrix mineralization was examined via von Kossa stain assay, total calcium deposition, and SEM. The hardness and elastic modulus of mineralized cultures were measured using a nano-indenter. The machined surface demonstrated a flat topographic configuration, while the acid-etched surface revealed a uniform micron-scale roughness. Both cell density and ALP activity were significantly higher on the machined surface than on the acid-etched surface. The expression of bone-related genes was up-regulated or enhanced on the acid-etched surface compared to the machined surface. Von Kossa stain showed significantly greater positive areas for the machined surface compared to the acid-etched surface, while total calcium deposition was statistically similar. Mineralized culture on the acid-etched surface was characterized by denser calcium deposition, more mature collagen deposition on the superficial layer, and larger and denser globular matrices inside the matrix than the culture on the machined surface. The mineralized matrix on the acid-etched surface was two times harder than on the machined surface, whereas the elastic modulus was comparable between the two surfaces. The design of this study can be used as a model to evaluate the effect of implant surface topography on the biomechanical properties of periosteum-derived mineralized culture. The results suggest that mandibular periosteal cells respond to different titanium surface topographies differently enough to produce mineralized matrices with different biomechanical qualities.

A Comparative Biomechanical Analysis of 2 Double-Row, Distal Triceps Tendon Repairs.

PubMed

Dorweiler, Matthew A; Van Dyke, Rufus O; Siska, Robert C; Boin, Michael A; DiPaola, Mathew J

2017-05-01

Triceps tendon ruptures are rare orthopaedic injuries that almost always require surgical repair. This study tests the biomechanical properties of an original anchorless double-row triceps repair against a previously reported knotless double-row repair. The anchorless double-row triceps repair technique will yield similar biomechanical properties when compared with the knotless double-row repair technique. Controlled laboratory study. Eighteen cadaver arms were randomized into 2 groups. One group received the anchorless repair and the other received the knotless anchor repair. A materials testing system (MTS) machine was used to cycle the repaired arms from 0° to 90° with a 2.5-pound weight for 1500 cycles at 0.25 Hz. Real-time displacement of the tendon was measured during cycling using a probe. Load to failure was performed after completion of cyclic loading. The mean displacement with the anchorless technique was 0.77 mm (SD, 0.25 mm) at 0° (full elbow extension) and 0.76 mm (SD, 0.38 mm) at 90° (elbow flexion). The mean displacement with the anchored technique was 0.83 mm (SD, 0.57 mm) at 0° and 1.01 mm (SD, 0.62 mm) at 90°. There was no statistically significant difference for tendon displacement at 0º ( P = .75) or 90º ( P = .31). The mean load to failure with the anchorless technique was 618.9 N (SD, 185.6 N), while it was 560.5 N (SD, 154.1 N) with the anchored technique, again with no statistically significant difference ( P = .28). Our anchorless double-row triceps repair technique yields comparable biomechanical properties to previously described double-row triceps tendon repair techniques, with the added benefit of avoiding the cost of suture anchors. This anchorless double-row triceps tendon repair can be considered as an acceptable alternative to a knotless anchor repair for triceps tendon ruptures.

Bone regeneration performance of surface-treated porous titanium.

PubMed

Amin Yavari, Saber; van der Stok, Johan; Chai, Yoke Chin; Wauthle, Ruben; Tahmasebi Birgani, Zeinab; Habibovic, Pamela; Mulier, Michiel; Schrooten, Jan; Weinans, Harrie; Zadpoor, Amir Abbas

2014-08-01

The large surface area of highly porous titanium structures produced by additive manufacturing can be modified using biofunctionalizing surface treatments to improve the bone regeneration performance of these otherwise bioinert biomaterials. In this longitudinal study, we applied and compared three types of biofunctionalizing surface treatments, namely acid-alkali (AcAl), alkali-acid-heat treatment (AlAcH), and anodizing-heat treatment (AnH). The effects of treatments on apatite forming ability, cell attachment, cell proliferation, osteogenic gene expression, bone regeneration, biomechanical stability, and bone-biomaterial contact were evaluated using apatite forming ability test, cell culture assays, and animal experiments. It was found that AcAl and AnH work through completely different routes. While AcAl improved the apatite forming ability of as-manufactured (AsM) specimens, it did not have any positive effect on cell attachment, cell proliferation, and osteogenic gene expression. In contrast, AnH did not improve the apatite forming ability of AsM specimens but showed significantly better cell attachment, cell proliferation, and expression of osteogenic markers. The performance of AlAcH in terms of apatite forming ability and cell response was in between both extremes of AnH and AsM. AcAl resulted in significantly larger volumes of newly formed bone within the pores of the scaffold as compared to AnH. Interestingly, larger volumes of regenerated bone did not translate into improved biomechanical stability as AnH exhibited significantly better biomechanical stability as compared to AcAl suggesting that the beneficial effects of cell-nanotopography modulations somehow surpassed the benefits of improved apatite forming ability. In conclusion, the applied surface treatments have considerable effects on apatite forming ability, cell attachment, cell proliferation, and bone ingrowth of the studied biomaterials. The relationship between these properties and the bone-implant biomechanics is, however, not trivial. Copyright © 2014 Elsevier Ltd. All rights reserved.

Cement augmentation of implants--no general cure in osteoporotic fracture treatment. A biomechanical study on non-displaced femoral neck fractures.

PubMed

Hofmann-Fliri, Ladina; Nicolino, Tomas I; Barla, Jorge; Gueorguiev, Boyko; Richards, R Geoff; Blauth, Michael; Windolf, Markus

2016-02-01

Femoral neck fractures in the elderly are a common problem in orthopedics. Augmentation of screw fixation with bone cement can provide better stability of implants and lower the risk of secondary displacement. This study aimed to investigate whether cement augmentation of three cannulated screws in non-displaced femoral neck fractures could increase implant fixation. A femoral neck fracture was simulated in six paired human cadaveric femora and stabilized with three 7.3 mm cannulated screws. Pairs were divided into two groups: conventional instrumentation versus additional cement augmentation of screw tips with 2 ml TraumacemV+ each. Biomechanical testing was performed by applying cyclic axial load until failure. Failure cycles, axial head displacement, screw angle changes, telescoping and screw cut-out were evaluated. Failure (15 mm actuator displacement) occurred in the augmented group at 12,500 cycles (± 2,480) compared to 15,625 cycles (± 4,215) in the non-augmented group (p = 0.041). When comparing 3 mm vertical displacement of the head no significant difference (p = 0.72) was detected between the survival curves of the two groups. At 8,500 load-cycles (early onset failure) the augmented group demonstrated a change in screw angle of 2.85° (± 0.84) compared to 1.15° (± 0.93) in the non-augmented group (p = 0.013). The results showed no biomechanical advantage with respect to secondary displacement following augmentation of three cannulated screws in a non-displaced femoral neck fracture. Consequently, the indication for cement augmentation to enhance implant anchorage in osteoporotic bone has to be considered carefully taking into account fracture type, implant selection and biomechanical surrounding. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Biomechanical Differences of Foot-Strike Patterns During Running: A Systematic Review With Meta-analysis.

PubMed

Almeida, Matheus O; Davis, Irene S; Lopes, Alexandre D

2015-10-01

Systematic review with meta-analysis. To determine the biomechanical differences between foot-strike patterns used when running. Strike patterns during running have received attention in the recent literature due to their potential mechanical differences and associated injury risks. Electronic databases (MEDLINE, Embase, LILACS, SciELO, and SPORTDiscus) were searched through July 2014. Studies (cross-sectional, case-control, prospective, and retrospective) comparing the biomechanical characteristics of foot-strike patterns during running in distance runners at least 18 years of age were included in this review. Two independent reviewers evaluated the risk of bias. A meta-analysis with a random-effects model was used to combine the data from the included studies. Sixteen studies were included in the final analysis. In the meta-analyses of kinematic variables, significant differences between forefoot and rearfoot strikers were found for foot and knee angle at initial contact and knee flexion range of motion. A forefoot-strike pattern resulted in a plantar-flexed ankle position and a more flexed knee position, compared to a dorsiflexed ankle position and a more extended knee position for the rearfoot strikers, at initial contact with the ground. In the comparison of rearfoot and midfoot strikers, midfoot strikers demonstrated greater ankle dorsiflexion range of motion and decreased knee flexion range of motion compared to rearfoot strikers. For kinetic variables, the meta-analysis revealed that rearfoot strikers had higher vertical loading rates compared to forefoot strikers. There are differences in kinematic and kinetic characteristics between foot-strike patterns when running. Clinicians should be aware of these characteristics to help in the management of running injuries and advice on training.

A novel strategy to translate the biomechanical rupture risk of abdominal aortic aneurysms to their equivalent diameter risk: method and retrospective validation.

PubMed

Gasser, T C; Nchimi, A; Swedenborg, J; Roy, J; Sakalihasan, N; Böckler, D; Hyhlik-Dürr, A

2014-03-01

To translate the individual abdominal aortic aneurysm (AAA) patient's biomechanical rupture risk profile to risk-equivalent diameters, and to retrospectively test their predictability in ruptured and non-ruptured aneurysms. Biomechanical parameters of ruptured and non-ruptured AAAs were retrospectively evaluated in a multicenter study. General patient data and high resolution computer tomography angiography (CTA) images from 203 non-ruptured and 40 ruptured aneurysmal infrarenal aortas. Three-dimensional AAA geometries were semi-automatically derived from CTA images. Finite element (FE) models were used to predict peak wall stress (PWS) and peak wall rupture index (PWRI) according to the individual anatomy, gender, blood pressure, intra-luminal thrombus (ILT) morphology, and relative aneurysm expansion. Average PWS diameter and PWRI diameter responses were evaluated, which allowed for the PWS equivalent and PWRI equivalent diameters for any individual aneurysm to be defined. PWS increased linearly and PWRI exponentially with respect to maximum AAA diameter. A size-adjusted analysis showed that PWS equivalent and PWRI equivalent diameters were increased by 7.5 mm (p = .013) and 14.0 mm (p < .001) in ruptured cases when compared to non-ruptured controls, respectively. In non-ruptured cases the PWRI equivalent diameters were increased by 13.2 mm (p < .001) in females when compared with males. Biomechanical parameters like PWS and PWRI allow for a highly individualized analysis by integrating factors that influence the risk of AAA rupture like geometry (degree of asymmetry, ILT morphology, etc.) and patient characteristics (gender, family history, blood pressure, etc.). PWRI and the reported annual risk of rupture increase similarly with the diameter. PWRI equivalent diameter expresses the PWRI through the diameter of the average AAA that has the same PWRI, i.e. is at the same biomechanical risk of rupture. Consequently, PWRI equivalent diameter facilitates a straightforward interpretation of biomechanical analysis and connects to diameter-based guidelines for AAA repair indication. PWRI equivalent diameter reflects an additional diagnostic parameter that may provide more accurate clinical data for AAA repair indication. Copyright © 2013 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Preliminary evidence of altered biomechanics in adolescents with juvenile fibromyalgia.

PubMed

Sil, Soumitri; Thomas, Staci; DiCesare, Christopher; Strotman, Daniel; Ting, Tracy V; Myer, Gregory; Kashikar-Zuck, Susmita

2015-01-01

Juvenile fibromyalgia (FM) is characterized by chronic musculoskeletal pain and marked reduction in physical activity. Despite recommendations for exercise to manage juvenile FM pain, exercise adherence is poor. Because of pain and activity avoidance, adolescents with juvenile FM are at risk for altered joint mechanics that may make them susceptible to increased pain and reduced tolerance for exercise. The primary aim of this study was to assess functional deficits in patients with juvenile FM compared to healthy controls using objective biomechanical assessment. Female adolescent patients with juvenile FM (n = 17) and healthy controls (n = 14) completed biomechanical assessments, including gait analysis and tests of lower extremity strength (isokinetic knee extension/flexion and hip abduction) and functional performance (drop vertical jump test) along with self-reported measures of disability (Functional Disability Inventory), pain intensity, depressive symptoms (Children's Depression Inventory), and fear of movement (Tampa Scale of Kinesiophobia). Patients with juvenile FM demonstrated mild deficiencies in walking gait and functional performance (P < 0.05 for both) and significantly lower left knee extension and flexion strength (18-22% deficit) and bilateral hip abduction strength (34-38%) compared with healthy controls (P < 0.008 for all). Patients with juvenile FM reported significantly higher functional disability, pain intensity, depressive symptoms, and fear of movement relative to controls (P < 0.01 for all). This study showed that adolescents with juvenile FM exhibited objective alterations in biomechanics and self-reported fear of movement that may have reinforced their activity avoidance. Interventions for juvenile FM should include a focus on correcting functional deficits and instilling greater confidence in adolescents with juvenile FM to engage in exercise to improve functional outcomes. Copyright © 2015 by the American College of Rheumatology.

Biomechanical risk factors for proximal junctional kyphosis: a detailed numerical analysis of surgical instrumentation variables.

PubMed

Cammarata, Marco; Aubin, Carl-Éric; Wang, Xiaoyu; Mac-Thiong, Jean-Marc

2014-04-15

Biomechanical analysis of proximal junctional kyphosis (PJK) through computer simulations and sensitivity analysis. To gain biomechanical knowledge on the risk of PJK and find surgical solutions to reduce the risks. PJK is a pathological kyphotic deformity adjacent to the instrumentation. Clinical studies have documented its risk factors, but still little is known on how it is correlated with various individual instrumentation variables. Biomechanical spine models of 6 patients with adult scoliosis were developed, validated, and then used to perform 576 simulations, varying the proximal dissection procedure, the implant type at the upper instrumented vertebra, the sagittal rod curvature, and the proximal diameter of the proximal transition rods. Four biomechanical indices--the proximal junctional kyphotic angle, thoracic kyphosis, proximal flexion force, and proximal flexion moment--were assessed. The bilateral complete facetectomy, the posterior ligaments resection, and the combination of both increased the proximal junctional kyphotic angle (respectively, by 10%, 28% and 53%) and the proximal flexion force (4%, 12%, and 22%) and moment (16%, 44%, and 83%). Compared with pedicle screws at upper instrumented vertebra, proximal transverse process hooks reduced the 3 biomechanical indices by approximately 26%. The use of proximal transition rods with reduced proximal diameter from 5.5 mm to 4 mm decreased the proximal junctional kyphotic angle (by 6%) and the proximal flexion force (4%) and moment (8%). The increase of the sagittal rod curvature from 10° to 20°, 30°, and 40° increased the proximal junctional kyphotic angle (by 6%, 13%, and 19%) and the proximal flexion force (3%, 7%, and 10%) and moment (9%, 18%, and 27%). Preserving more posterior proximal intervertebral elements, the use of transition rods and transverse process hooks at upper instrumented vertebra, and reducing the global sagittal rod curvature each decreased the 4 biomechanical indices that may be involved in PJK. N/A.

Comparison of two tension-band fixation materials and techniques in transverse patella fractures: a biomechanical study.

PubMed

Rabalais, R David; Burger, Evalina; Lu, Yun; Mansour, Alfred; Baratta, Richard V

2008-02-01

This study compared the biomechanical properties of 2 tension-band techniques with stainless steel wire and ultra high molecular weight polyethylene (UHMWPE) cable in a patella fracture model. Transverse patella fractures were simulated in 8 cadaver knees and fixated with figure-of-8 and parallel wire configurations in combination with Kirschner wires. Identical configurations were tested with UHMWPE cable. Specimens were mounted to a testing apparatus and the quadriceps was used to extend the knees from 90 degrees to 0 degrees; 4 knees were tested under monotonic loading, and 4 knees were tested under cyclic loading. Under monotonic loading, average fracture gap was 0.50 and 0.57 mm for steel wire and UHMWPE cable, respectively, in the figure-of-8 construct compared with 0.16 and 0.04 mm, respectively, in the parallel wire construct. Under cyclic loading, average fracture gap was 1.45 and 1.66 mm for steel wire and UHMWPE cable, respectively, in the figure-of-8 construct compared with 0.45 and 0.60 mm, respectively, in the parallel wire construct. A statistically significant effect of technique was found, with the parallel wire construct performing better than the figure-of-8 construct in both loading models. There was no effect of material or interaction. In this biomechanical model, parallel wires performed better than the figure-of-8 configuration in both loading regimens, and UHMWPE cable performed similarly to 18-gauge steel wire.

Biomechanics of Submaximal Recumbent Cycling in Adolescents With and Without Cerebral Palsy

PubMed Central

Johnston, Therese E; Barr, Ann E; Lee, Samuel CK

2011-01-01

Background and Purpose The purpose of this study was to compare the biomechanics of recumbent cycling between adolescents with cerebral palsy (CP) classified at Gross Motor Function Classification System (GMFCS) levels III and IV and adolescents with typical development (TD). Subjects Twenty subjects, ages (X̄±SD) 15.2±1.6 years (10 with TD, 10 with CP), participated. Methods Lower-extremity kinematics and muscle activity were measured at 30 and 60 rpm while subjects pedaled on a recumbent cycle. Energy expenditure and perceived exertion were measured during a 5-minute test, and efficiency was calculated. Noncircular data were analyzed with analyses of variance. Circular data were analyzed using circular t tests. Results Differences were found between groups for joint kinematics for all motions. Subjects with CP displayed earlier onsets and later offsets of muscle activity, increased co-contraction of agonist and antagonist muscles, and decreased efficiency compared with subjects with TD. There were no differences in perceived exertion. Discussion and Conclusion Differences in cycling biomechanics between children with CP and children with TD may be due to decreased strength and motor control in the children with CP. PMID:17405804

Matrix Metalloproteinase 9 (MMP-9) Regulates Vein Wall Biomechanics in Murine Thrombus Resolution

PubMed Central

Nguyen, Khanh P.; McGilvray, Kirk C.; Puttlitz, Christian M.; Mukhopadhyay, Subhradip; Chabasse, Christine; Sarkar, Rajabrata

2015-01-01

Objective Deep venous thrombosis is a common vascular problem with long-term complications including post-thrombotic syndrome. Post-thrombotic syndrome consists of leg pain, swelling and ulceration that is related to incomplete or maladaptive resolution of the venous thrombus as well as loss of compliance of the vein wall. We examine the role of metalloproteinase-9 (MMP-9), a gene important in extracellular remodeling in other vascular diseases, in mediating thrombus resolution and biomechanical changes of the vein wall. Methods and Results The effects of targeted deletion of MMP-9 were studied in an in vivo murine model of thrombus resolution using the FVB strain of mice. MMP-9 expression and activity significantly increased on day 3 after DVT. The lack of MMP-9 impaired thrombus resolution by 27% and this phenotype was rescued by the transplantation of wildtype bone marrow cells. Using novel biomechanical techniques, we demonstrated that the lack of MMP-9 significantly decreased thrombus-induced loss of vein wall compliance. Biomechanical analysis of the contribution of individual structural components showed that MMP-9 affected the elasticity of the extracellular matrix and collagen-elastin fibers. Biochemical and histological analyses correlated with these biomechanical effects as thrombi of mice lacking MMP-9 had significantly fewer macrophages and collagen as compared to those of wildtype mice. Conclusions MMP-9 mediates thrombus-induced loss of vein wall compliance by increasing stiffness of the extracellular matrix and collagen-elastin fibers during thrombus resolution. MMP-9 also mediates macrophage and collagen content of the resolving thrombus and bone-marrow derived MMP-9 plays a role in resolution of thrombus mass. These disparate effects of MMP-9 on various aspects of thrombus illustrate the complexity of individual protease function on biomechanical and morphometric aspects of thrombus resolution. PMID:26406902

Biomechanical Indices for Rupture Risk Estimation in Abdominal Aortic Aneurysms.

PubMed

Leemans, Eva L; Willems, Tineke P; van der Laan, Maarten J; Slump, Cornelis H; Zeebregts, Clark J

2017-04-01

To review the use of biomechanical indices for the estimation of abdominal aortic aneurysm (AAA) rupture risk, emphasizing their potential use in a clinical setting. A search of the PubMed, Embase, Scopus, and Compendex databases was made up to June 2015 to identify articles involving biomechanical analysis of AAA rupture risk. Outcome variables [aneurysm diameter, peak wall stress (PWS), peak wall shear stress (PWSS), wall strain, peak wall rupture index (PWRI), and wall stiffness] were compared for asymptomatic intact AAAs vs symptomatic or ruptured AAAs. For quantitative analysis of the pooled data, a random effects model was used to calculate the standard mean differences (SMDs) with the 95% confidence interval (CI) for the biomechanical indices. The initial database searches yielded 1894 independent articles of which 19 were included in the analysis. The PWS was significantly higher in the symptomatic/ruptured group, with a SMD of 1.11 (95% CI 0.93 to 1.26, p<0.001). Likewise, the PWRI was significantly higher in the ruptured or symptomatic group, with a SMD of 1.15 (95% CI 0.30 to 2.01, p=0.008). After adjustment for the aneurysm diameter, the PWS remained higher in the ruptured or symptomatic group, with a SMD of 0.85 (95% CI 0.46 to 1.23, p<0.001). Less is known of the wall shear stress and wall strain indices, as too few studies were available for analysis. Biomechanical indices are a promising tool in the assessment of AAA rupture risk as they incorporate several factors, including geometry, tissue properties, and patient-specific risk factors. However, clinical implementation of biomechanical AAA assessment remains a challenge owing to a lack of standardization.

Trunk and lower limb biomechanics during stair climbing in people with and without symptomatic femoroacetabular impingement.

PubMed

Hammond, Connor A; Hatfield, Gillian L; Gilbart, Michael K; Garland, S Jayne; Hunt, Michael A

2017-02-01

Femoroacetabular impingement is a pathomechanical hip condition leading to pain and impaired physical function. It has been shown that those with femoroacetabular impingement exhibit altered gait characteristics during level walking and stair climbing, and decreased muscle force production during isometric muscle contractions. However, no studies to-date have looked at trunk kinematics or muscle activation during dynamic movements such as stair climbing in this patient population. The purpose of this study was to compare biomechanical outcomes (trunk and lower limb kinematics as well as lower limb kinetics and muscle activation) during stair climbing in those with and without symptomatic femoroacetabular impingement. Trunk, hip, knee and ankle kinematics, as well as hip, knee and ankle kinetics and muscle activity of nine lower limb muscles were collected during stair climbing for 20 people with clinical and radiographic femoroacetabular impingement and compared to 20 age- and sex-matched pain-free individuals. Those with femoroacetabular impingement ascended the stairs slower (effect size=0.82), had significantly increased peak trunk forward flexion angles (effect size=0.99) and external hip flexion moments (effect size=0.94) and had decreased peak external knee flexion moments (effect size=0.90) compared to the control group. Findings from this study indicate that while those with and without femoroacetabular impingement exhibit many biomechanical similarities when ascending stairs, differences in trunk forward flexion and joint kinetics indicate some important differences. Further longitudinal research is required to elucidate the cause of these differences as well as the clinical relevance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rotator cuff healing after continuous subacromial bupivacaine infusion: an in vivo rabbit study

PubMed Central

FRIEL, NICOLE A.; WANG, VINCENT M.; SLABAUGH, MARK A.; WANG, FANCHIA; CHUBINSKAYA, SUSAN; COLE, BRIAN J.

2013-01-01

Background The objective of this study was to evaluate the effects of continuous subacromial bupivacaine infusion on supraspinatus muscle and rotator cuff tendon healing via gross, biomechanical, and histologic analyses. Methods Thirty-three New Zealand White rabbits underwent unilateral supraspinatus transection and rotator cuff repair (RCR). Rabbits were assigned to 1 of 3 groups: (1)RCR only, (2)RCR with continuous saline infusion for 48 hours, or (3)RCR with continuous 0.25% bupivacaine with epinephrine (1:200,000) infusion for 48 hours. Rabbits were sacrificed at either 2 (for histologic assessment) or 8 weeks post-operatively (for biomechanical and histologic assessment). Results Tensile testing showed significantly higher load to failure in intact tendons compared to repaired tendons (p<0.01); however, no statistical differences were detected among RCR only, RCR Saline, and RCR Bupivacaine groups. Histologically, the enthesis of repaired tendons showed increased cellularity and disorganized collagen fibers compared to intact tendons, with no differences between treatment groups. Muscle histology demonstrated scattered degenerative muscle fibers at 2 weeks in both RCR Saline and RCR Bupivacaine, but no degeneration was noted at 8 weeks. Conclusions The healing supraspinatus tendons exposed to bupivacaine infusion showed similar histologic and biomechanical characteristics compared to untreated and saline infused RCR groups. Muscle histology showed fiber damage at 2 weeks for both the saline and bupivacaine treated groups, with no apparent disruption at 8 weeks, suggesting a recovery process. Therefore, subacromial bupivacaine infusion in this rabbit rotator cuff model does not appear to impair muscle or tendon following acute injury and repair. Level Of Evidence Basic science study PMID:22818894

Linear and Nonlinear Viscoelastic Modeling of Aorta and Carotid Pressure-Area Dynamics under in vivo and ex vivo Conditions

PubMed Central

Valdez-Jasso, Daniela; Bia, Daniel; Zócalo, Yanina; Armentano, Ricardo L.; Haider, Mansoor A.; Olufsen, Mette S.

2013-01-01

A better understanding of the biomechanical properties of the arterial wall provides important insight into arterial vascular biology under normal (healthy) and pathological conditions. This insight has potential to improve tracking of disease progression and to aid in vascular graft design and implementation. In this study, we use linear and nonlinear viscoelastic models to predict biomechanical properties of the thoracic descending aorta and the carotid artery under ex vivo and in vivo conditions in ovine and human arteries. Models analyzed include a four-parameter (linear) Kelvin viscoelastic model and two five-parameter nonlinear viscoelastic models (an arctangent and a sigmoid model) that relate changes in arterial blood pressure to the vessel cross-sectional area (via estimation of vessel strain). These models were developed using the framework of Quasilinear Viscoelasticity (QLV) theory and were validated using measurements from the thoracic descending aorta and the carotid artery obtained from human and ovine arteries. In vivo measurements were obtained from ten ovine aortas and ten human carotid arteries. Ex vivo measurements (from both locations) were made in eleven male Merino sheep. Biomechanical properties were obtained through constrained estimation of model parameters. To further investigate the parameter estimates we computed standard errors and confidence intervals and we used analysis of variance to compare results within and between groups. Overall, our results indicate that optimal model selection depends on the arterial type. Results showed that for the thoracic descending aorta (under both experimental conditions) the best predictions were obtained with the nonlinear sigmoid model, while under healthy physiological pressure loading the carotid arteries nonlinear stiffening with increasing pressure is negligible, and consequently, the linear (Kelvin) viscoelastic model better describes the pressure-area dynamics in this vessel. Results comparing biomechanical properties show that the Kelvin and sigmoid models were able to predict the zero-pressure vessel radius; that under ex vivo conditions vessels are more rigid, and comparatively, that the carotid artery is stiffer than the thoracic descending aorta; and that the viscoelastic gain and relaxation parameters do not differ significantly between vessels or experimental conditions. In conclusion, our study demonstrates that the proposed models can predict pressure-area dynamics and that model parameters can be extracted for further interpretation of biomechanical properties. PMID:21203846

Direct lateral approach to lumbar fusion is a biomechanically equivalent alternative to the anterior approach: an in vitro study.

PubMed

Laws, Cory J; Coughlin, Dezba G; Lotz, Jeffrey C; Serhan, Hassan A; Hu, Serena S

2012-05-01

A human cadaveric biomechanical study of lumbar mobility before and after fusion and with or without supplemental instrumentation for 5 instrumentation configurations. To determine the biomechanical differences between anterior lumbar interbody fusion (ALIF) and direct lateral interbody fusion (DLIF) with and without supplementary instrumentation. Some prior studies have compared various surgical approaches using the same interbody device whereas others have investigated the stabilizing effect of supplemental instrumentation. No published studies have performed a side-by-side comparison of standard and minimally invasive techniques with and without supplemental instrumentation. Eight human lumbosacral specimens (16 motion segments) were tested in each of the 5 following configurations: (1) intact, (2) with ALIF or DLIF cage, (3) with cage plus stabilizing plate, (4) with cage plus unilateral pedicle screw fixation (PSF), and (5) with cage plus bilateral PSF. Pure moments were applied to induce specimen flexion, extension, lateral bending, and axial rotation. Three-dimensional kinematic responses were measured and used to calculate range of motion, stiffness, and neutral zone. Compared to the intact state, DLIF significantly reduced range of motion in flexion, extension, and lateral bending (P = 0.0117, P = 0.0015, P = 0.0031). Supplemental instrumentation significantly increased fused-specimen stiffness for both DLIF and ALIF groups. For the ALIF group, bilateral PSF increased stiffness relative to stand-alone cage by 455% in flexion and 317% in lateral bending (P = 0.0009 and P < 0.0001). The plate increased ALIF group stiffness by 211% in extension and 256% in axial rotation (P = 0.0467 and P = 0.0303). For the DLIF group, bilateral PSF increased stiffness by 350% in flexion and 222% in extension (P < 0.0001 and P = 0.0008). No differences were observed between ALIF and DLIF groups supplemented with bilateral PSF. Our data support that the direct lateral approach, when supplemented with bilateral PSF, is a minimally invasive and biomechanically stable alternative to the open, anterior approach to lumbar spine fusion.

In Vivo Multiphoton Microscopy for Investigating Biomechanical Properties of Human Skin.

PubMed

Liang, Xing; Graf, Benedikt W; Boppart, Stephen A

2011-06-01

The biomechanical properties of living cells depend on their molecular building blocks, and are important for maintaining structure and function in cells, the extracellular matrix, and tissues. These biomechanical properties and forces also shape and modify the cellular and extracellular structures under stress. While many studies have investigated the biomechanics of single cells or small populations of cells in culture, or the properties of organs and tissues, few studies have investigated the biomechanics of complex cell populations in vivo. With the use of advanced multiphoton microscopy to visualize in vivo cell populations in human skin, the biomechanical properties are investigated in a depth-dependent manner in the stratum corneum and epidermis using quasi-static mechanical deformations. A 2D elastic registration algorithm was used to analyze the images before and after deformation to determine displacements in different skin layers. In this feasibility study, the images and results from one human subject demonstrate the potential of the technique for revealing differences in elastic properties between the stratum corneum and the rest of the epidermis. This interrogational imaging methodology has the potential to enable a wide range of investigations for understanding how the biomechanical properties of in vivo cell populations influence function in health and disease.

Relationships between job organisational factors, biomechanical and psychosocial exposures.

PubMed

Bao, Stephen S; Kapellusch, Jay M; Merryweather, Andrew S; Thiese, Matthew S; Garg, Arun; Hegmann, Kurt T; Silverstein, Barbara A

2016-01-01

The relationships between work organisational, biomechanical and psychosocial factors were studied using cross-sectional data from a pooled dataset of 1834 participants. The work organisational factors included: job rotation, overtime work, having second jobs and work pace. Task and job level biomechanical variables were obtained through sub-task data collected in the field or analysed in the laboratory. Psychosocial variables were collected based on responses to 10 questions. The results showed that job rotations had significant effects on all biomechanical and most psychosocial measures. Those with job rotations generally had higher job biomechanical stressors, and lower job satisfaction. Overtime work was associated with higher job biomechanical stressors, and possibly self-reported physical exhaustion. Those having second jobs reported getting along with co-workers well. Work pace had significant influences on all biomechanical stressors, but its impact on job biomechanical stressors and psychosocial effects are complicated. The findings are based on a large number of subjects collected by three research teams in diverse US workplaces. Job rotation practices used in many workplaces may not be effective in reducing job biomechanical stressors for work-related musculoskeletal disorders. Overtime work is also associated with higher biomechanical stressors.

Human elastin polypeptides improve the biomechanical properties of three-dimensional matrices through the regulation of elastogenesis.

PubMed

Boccafoschi, Francesca; Ramella, Martina; Sibillano, Teresa; De Caro, Liberato; Giannini, Cinzia; Comparelli, Roberto; Bandiera, Antonella; Cannas, Mario

2015-03-01

The replacement of diseased tissues with biological substitutes with suitable biomechanical properties is one of the most important goal in tissue engineering. Collagen represents a satisfactory choice for scaffolds. Unfortunately, the lack of elasticity represents a restriction to a wide use of collagen for several applications. In this work, we studied the effect of human elastin-like polypeptide (HELP) as hybrid collagen-elastin matrices. In particular, we studied the biomechanical properties of collagen/HELP scaffolds considering several components involved in ECM remodeling (elastin, collagen, fibrillin, lectin-like receptor, metalloproteinases) and cell phenotype (myogenin, myosin heavy chain) with particular awareness for vascular tissue engineering applications. Elastin and collagen content resulted upregulated in collagen-HELP matrices, even showing an improved structural remodeling through the involvement of proteins to a ECM remodeling activity. Moreover, the hybrid matrices enhanced the contractile activity of C2C12 cells concurring to improve the mechanical properties of the scaffold. Finally, small-angle X-ray scattering analyses were performed to enable a very detailed analysis of the matrices at the nanoscale, comparing the scaffolds with native blood vessels. In conclusion, our work shows the use of recombinant HELP, as a very promising complement able to significantly improve the biomechanical properties of three-dimensional collagen matrices in terms of tensile stress and elastic modulus. © 2014 Wiley Periodicals, Inc.

[Rotator cuff repair: single- vs double-row. Clinical and biomechanical results].

PubMed

Baums, M H; Kostuj, T; Klinger, H-M; Papalia, R

2016-02-01

The goal of rotator cuff repair is a high initial mechanical stability as a requirement for adequate biological recovery of the tendon-to-bone complex. Notwithstanding the significant increase in publications concerning the topic of rotator cuff repair, there are still controversies regarding surgical technique. The aim of this work is to present an overview of the recently published results of biomechanical and clinical studies on rotator cuff repair using single- and double-row techniques. The review is based on a selective literature research of PubMed, Embase, and the Cochrane Database on the subject of the clinical and biomechanical results of single- and double-row repair. In general, neither the biomechanical nor the clinical evidence can recommend the use of a double-row concept for the treatment for every rotator cuff tear. Only tears of more than 3 cm seem to benefit from better results on both imaging and in clinical outcome studies compared with the use of single-row techniques. Despite a significant increase in publications on the surgical treatment of rotator cuff tears in recent years, the clinical results were not significantly improved in the literature so far. Unique information and algorithms, from which the optimal treatment of this entity can be derived, are still inadequate. Because of the cost-effectiveness and the currently vague evidence, the double-row techniques cannot be generally recommended for the repair of all rotator cuff tears.

Effect of dermal thickness, tissue composition, and body site on skin biomechanical properties.

PubMed

Smalls, Lola K; Randall Wickett, R; Visscher, Marty O

2006-02-01

Quantitative measurement of skin biomechanical properties has been used effectively in the investigation of physiological changes in tissue structure and function and to determine treatment efficacy. As the methods are applied to new questions, tissue characteristics that may influence the resultant biomechanical properties are important considerations in the research design. For certain applications, variables such as dermal thickness and subdermal tissue composition, as well as age and/or solar exposure, may influence the skin biomechanics. We determined the influence of dermal thickness, tissue composition, and age on the skin biomechanical properties at the shoulder, thigh, and calf among 30 healthy females. We compared two devices, the Biomechanical Tissue Characterization System and the Cutometer SEM 575 Skin Elasticity Meter , to determine the effect of tissue sampling size. Dermal thickness was measured with 20 MHz ultrasound (Dermascan C) and tissue composition was inferred from anthropomorphic data. Skin thickness was significantly correlated with stiffness, energy absorption, and U(r)/U(f) for the shoulder. Body mass index (BMI) was significantly correlated with stiffness (negative correlation), energy absorption (positive), and skin thickness (negative) for the shoulder. Significant differences across body sites were observed. The calf was significantly different from the thigh and shoulders for all parameters (P<0.05, one-way anova). The calf had significantly lower laxity, laxity%, elastic deformation, energy absorption, elasticity, elasticity %, U(r), U(f), and U(r)/U(f) and significantly higher stiffness compared with the thighs and shoulders. sites. The thigh and shoulder sites were significantly different for all parameters except U(r)/U(f), elasticity %, laxity%, and stiffness. The dominant and non-dominant sides were significantly different. The dominant side (right for 90% of the subjects) had increased stiffness and decreased energy absorption (tissue softness, compliance) compared with the left side. A significant (P< or =0.02) negative relationship with age was seen for all biomechanical measures except stiffness at the shoulder. For the thigh and calf sites, significant negative correlations with age were found for elasticity %, U(r), and U(r)/U(f). Age and skin thickness were not correlated in this population. Skin thickness and age influenced the energy absorption at the shoulder site. The biological elasticity at the calf site could be predicted by age and BMI. The biological activity at the thigh site could be predicted by skin thickness and BMI. Significant regional variations in biomechanical properties and dominant side effects were observed. The biomechanical properties were significantly influenced by age. Certain properties varied with dermal thickness and tissue composition. The parameters were well correlated between the two instruments. The Cutometer, with its smaller aperture, was found to be more sensitive to age relationships.

Does a single gait training session performed either overground or on a treadmill induce specific short-term effects on gait parameters in patients with hemiparesis? A randomized controlled study.

PubMed

Bonnyaud, Céline; Pradon, Didier; Zory, Raphael; Bensmail, Djamel; Vuillerme, Nicolas; Roche, Nicolas

2013-01-01

Gait training for patients with hemiparesis is carried out independently overground or on a treadmill. Several studies have shown differences in hemiparetic gait parameters during overground versus treadmill walking. However, few studies have compared the effects of these 2 gait training conditions on gait parameters, and no study has compared the short-term effects of these techniques on all biomechanical gait parameters. To determine whether a gait training session performed overground or on a treadmill induces specific short-term effects on biomechanical gait parameters in patients with hemiparesis. Twenty-six subjects with hemiparesis were randomly assigned to a single session of either overground or treadmill gait training. The short-term effects on spatiotemporal, kinematic, and kinetic gait parameters were assessed using gait analysis before and immediately after the training and after a 20-minute rest. Speed, cadence, percentage of single support phase, peak knee extension, peak propulsion, and braking on the paretic side were significantly increased after the gait training session. However, there were no specific changes dependent on the type of gait training performed (overground or on a treadmill). A gait training session performed by subjects with hemiparesis overground or on a treadmill did not induce specific short-term effects on biomechanical gait parameters. The increase in gait velocity that followed a gait training session seemed to reflect specific modifications of the paretic lower limb and adaptation of the nonparetic lower limb.

Arch index and running biomechanics in children aged 10-14 years.

PubMed

Hollander, Karsten; Stebbins, Julie; Albertsen, Inke Marie; Hamacher, Daniel; Babin, Kornelia; Hacke, Claudia; Zech, Astrid

2018-03-01

While altered foot arch characteristics (high or low) are frequently assumed to influence lower limb biomechanics and are suspected to be a contributing factor for injuries, the association between arch characteristics and lower limb running biomechanics in children is unclear. Therefore, the aim of this study was to investigate the relationship between a dynamically measured arch index and running biomechanics in healthy children. One hundred and one children aged 10-14 years were included in this study and underwent a biomechanical investigation. Plantar distribution (Novel, Emed) was used to determine the dynamic arch index and 3D motion capture (Vicon) to measure running biomechanics. Linear mixed models were established to determine the association between dynamic arch index and foot strike patterns, running kinematics, kinetics and temporal-spatial outcomes. No association was found between dynamic arch index and rate of rearfoot strikes (p = 0.072). Of all secondary outcomes, only the foot progression angle was associated with the dynamic arch index (p = 0.032) with greater external rotation in lower arched children. Overall, we found only few associations between arch characteristics and running biomechanics in children. However, altered foot arch characteristics are of clinical interest. Future studies should focus on detailed foot biomechanics and include clinically diagnosed high and low arched children. Copyright © 2018 Elsevier B.V. All rights reserved.

Factors Related to Students' Learning of Biomechanics Concepts

ERIC Educational Resources Information Center

Hsieh, ChengTu; Smith, Jeremy D.; Bohne, Michael; Knudson, Duane

2012-01-01

The purpose of this study was to replicate and expand a previous study to identify the factors that affect students' learning of biomechanical concepts. Students were recruited from three universities (N = 149) located in the central and western regions of the United States. Data from 142 students completing the Biomechanics Concept Inventory…

MR morphology of triangular fibrocartilage complex: correlation with quantitative MR and biomechanical properties.

PubMed

Bae, Won C; Ruangchaijatuporn, Thumanoon; Chang, Eric Y; Biswas, Reni; Du, Jiang; Statum, Sheronda; Chung, Christine B

2016-04-01

To evaluate pathology of the triangular fibrocartilage complex (TFCC) using high-resolution morphologic magnetic resonance (MR) imaging, and compare with quantitative MR and biomechanical properties. Five cadaveric wrists (22-70 years) were imaged at 3 T using morphologic (proton density weighted spin echo, PD FS, and 3D spoiled gradient echo, 3D SPGR) and quantitative MR sequences to determine T2 and T1rho properties. In eight geographic regions, morphology of TFC disc and laminae were evaluated for pathology and quantitative MR values. Samples were disarticulated and biomechanical indentation testing was performed on the distal surface of the TFC disc. On morphologic PD SE images, TFC disc pathology included degeneration and tears, while that of the laminae included degeneration, degeneration with superimposed tear, mucinous transformation, and globular calcification. Punctate calcifications were highly visible on 3D SPGR images and found only in pathologic regions. Disc pathology occurred more frequently in proximal regions of the disc than distal regions. Quantitative MR values were lowest in normal samples, and generally higher in pathologic regions. Biomechanical testing demonstrated an inverse relationship, with indentation modulus being high in normal regions with low MR values. The laminae studied were mostly pathologic, and additional normal samples are needed to discern quantitative changes. These results show technical feasibility of morphologic MR, quantitative MR, and biomechanical techniques to characterize pathology of the TFCC. Quantitative MRI may be a suitable surrogate marker of soft tissue mechanical properties, and a useful adjunct to conventional morphologic MR techniques.

Fully automated segmentation of callus by micro-CT compared to biomechanics.

PubMed

Bissinger, Oliver; Götz, Carolin; Wolff, Klaus-Dietrich; Hapfelmeier, Alexander; Prodinger, Peter Michael; Tischer, Thomas

2017-07-11

A high percentage of closed femur fractures have slight comminution. Using micro-CT (μCT), multiple fragment segmentation is much more difficult than segmentation of unfractured or osteotomied bone. Manual or semi-automated segmentation has been performed to date. However, such segmentation is extremely laborious, time-consuming and error-prone. Our aim was to therefore apply a fully automated segmentation algorithm to determine μCT parameters and examine their association with biomechanics. The femura of 64 rats taken after randomised inhibitory or neutral medication, in terms of the effect on fracture healing, and controls were closed fractured after a Kirschner wire was inserted. After 21 days, μCT and biomechanical parameters were determined by a fully automated method and correlated (Pearson's correlation). The fully automated segmentation algorithm automatically detected bone and simultaneously separated cortical bone from callus without requiring ROI selection for each single bony structure. We found an association of structural callus parameters obtained by μCT to the biomechanical properties. However, results were only explicable by additionally considering the callus location. A large number of slightly comminuted fractures in combination with therapies that influence the callus qualitatively and/or quantitatively considerably affects the association between μCT and biomechanics. In the future, contrast-enhanced μCT imaging of the callus cartilage might provide more information to improve the non-destructive and non-invasive prediction of callus mechanical properties. As studies evaluating such important drugs increase, fully automated segmentation appears to be clinically important.

Biomechanics in dermatology: Recent advances and future directions.

PubMed

Lewinson, Ryan T; Haber, Richard M

2017-02-01

Biomechanics is increasingly being recognized as an important research area in dermatology. To highlight only a few examples, biomechanics has contributed to the development of novel topical therapies for aesthetic and medical purposes, enhanced our understanding of the pathogenesis of plantar melanoma, and provided insight into the epidemiology of psoriatic disease. This article summarizes the findings from recent studies to demonstrate the important role that biomechanics may have in dermatologic disease and therapy and places these biomechanical findings in a clinical context for the practicing physician. In addition, areas for future biomechanics research and development in dermatology are discussed. Copyright © 2016 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

Biomechanical evaluation of different suture techniques for arthroscopic transtibial pull-out repair of posterior medial meniscus root tears.

PubMed

Feucht, Matthias J; Grande, Eduardo; Brunhuber, Johannes; Burgkart, Rainer; Imhoff, Andreas B; Braun, Sepp

2013-12-01

A tear of the posterior medial meniscus root (PMMR) is increasingly recognized as a serious knee joint injury. Several suture techniques for arthroscopic transtibial pull-out repair have been described; however, only limited data about the biomechanical properties of these techniques are currently available. There are significant differences between the tested suture techniques, with more complex suture configurations providing superior biomechanical properties. Controlled laboratory study. A total of 40 porcine medial menisci were randomly assigned to 1 of 4 groups (10 specimens each) according to suture technique: two simple stitches (TSS), horizontal mattress suture (HMS), modified Mason-Allen suture (MMA), and two modified loop stitches (TLS). Meniscus-suture constructs were subjected to cyclic loading followed by load-to-failure testing in a servohydraulic material testing machine. During cyclic loading, the HMS and TLS groups showed a significantly higher displacement after 100, 500, and 1000 cycles compared with the TSS and MMA groups. After 1000 cycles, the highest displacement was found for the TLS group, with significant differences compared with all other groups. During load-to-failure testing, the highest maximum load and yield load were observed for the MMA group, with statistically significant differences compared with the TSS and TLS groups. With regard to stiffness, the TSS and MMA groups showed significantly higher values compared with the HMS and TLS groups. The MMA technique provided the best biomechanical properties with regard to cyclic loading and load-to-failure testing. The TSS technique seems to be a valuable alternative. Both the HMS and TLS techniques have the disadvantage of lower stiffness and higher displacement during cyclic loading. Using a MMA technique may improve healing rates and avoid progressive extrusion of the medial meniscus after transtibial pull-out repair of PMMR tears. The TSS technique may be used as an alternative that is easier to perform, but a more careful rehabilitation program is possibly necessary to avoid early failure.

Biomedical perspectives on locomotion in null gravity

NASA Technical Reports Server (NTRS)

Cavanagh, Peter R.

1989-01-01

A number of important features of various locomotor activities are discussed, and approaches to the study of these activities in the context of space flight are suggested. In particular, the magnitude of peak forces and the rates of change of force during terrestrial cycling, walking, and running are compared. It is shown that subtle changes in the conditions and techniques of locomotion can have a major influence on the biomechanical consequences to the skeleton. The various hypotheses that identify locomotor exercise as a countermeasure to bone demineralization during weightlessness deserve to be tested with some degree of biomechanical rigor. Various approaches for achieving such scrutiny are discussed.

Fresh Osteochondral Allograft Versus Autograft: Twelve-Month Results in Isolated Canine Knee Defects.

PubMed

McCarty, Eric C; Fader, Ryan R; Mitchell, Justin J; Glenn, R Edward; Potter, Hollis G; Spindler, Kurt P

2016-09-01

Osteochondral autografts and allografts have been widely used in the treatment of isolated grade 4 articular cartilage lesions of the knee. However, there is a paucity of literature regarding the basic science investigating the direct comparison between fresh osteochondral allografts to autografts. At 12 months, fresh osteochondral allografts are equal to autografts with respect to function, bony incorporation into host bone, and chondrocyte viability. Controlled laboratory study. Eight adult mongrel dogs underwent bilateral hindlimb osteochondral graft implantation in the knee after creation of an acute Outerbridge grade 4 cartilage defect. One hindlimb of each dog knee received an autograft, and the contralateral knee received an allograft. All dogs were sacrificed at 12 months. Graft analysis included gross examination, radiographs, magnetic resonance imaging (MRI), biomechanical testing, and histology. MRI demonstrated excellent bony incorporation of both autografts and allografts, except for 1 allograft that revealed partial incorporation. Histologic examination of cartilage showed intact hyaline appearance for both autografts and allografts, with fibrocartilage at the host-graft interface of both. Biomechanical testing demonstrated no significant difference between allografts and autografts (P = .76). Furthermore, no significant difference was observed between allografts and the native cartilage with biomechanical testing (P = .84). After 12 months from time of implantation, fresh osteochondral allograft tissue and autograft tissue in this study were not statistically different with respect to biomechanical properties, gross morphology, bony incorporation, or overall histologic characteristics. When compared with the previously reported 6-month incorporation rates, there was improved allograft and autograft incorporation at 12 months. With no significant differences in gross examination, radiographs, MRI, biomechanical testing, or histology in the canine model, the use of allograft tissue to treat osteochondral defects may eliminate the morbidity associated with autograft harvest. © 2016 The Author(s).

Er:YAG laser: antimicrobial effects in the root canals of dogs' teeth with pulp necrosis and chronic periapical lesions.

PubMed

Leonardo, Mário R; Guillén-Carías, M G; Pécora, J D; Ito, I Y; Silva, L A B

2005-06-01

Our goal in this study was to evaluate the antimicrobial effect of Er:YAG laser applied after biomechanical preparation of the root canals of dog's teeth with apical periodontitis. Various in vitro studies have reported effective bacterial reduction in infected root canals using Er:YAG laser. However, there is no in vivo research to support these results. Forty root canals of dogs' premolar teeth with pulp necrosis and chronic periapical lesions were used. An initial microbiological sample was taken, and after biomechanical preparation was carried out, a second microbiological sample was taken. The teeth were divided into two groups: Group I-biomechanical preparation was taken of root canals without Er:YAG laser application; Group II-biomechanical preparation was taken of root canals with Er:YAG laser application using 140-mJ input, 63-mJ output/15 Hz. After coronal sealing, the root canals were left empty for 7 days at which time a third microbiological sample was taken. The collected material was removed from the root canal with a #40 K file and placed in transport media. It was serially diluted and seeded on culture dishes selective for anaerobes, aerobes, and total streptococci. Colony-forming units per milliliter (CFU/mL) were counted. Groups I and II showed an increase of CFU/mL for all microorganisms 7 days after treatment, being statistically significant for anaerobes in Group I and for anaerobes and total streptococci in Group II. When comparing CFU/mL of Groups I and II, there was a statistically significant increase after 7 d for total streptococci in Group II. Er:YAG laser applied after biomechanical preparation did not reduce microorganisms in the root canal system.

Adjacent level effects of bi level disc replacement, bi level fusion and disc replacement plus fusion in cervical spine--a finite element based study.

PubMed

Faizan, Ahmad; Goel, Vijay K; Biyani, Ashok; Garfin, Steven R; Bono, Christopher M

2012-03-01

Studies delineating the adjacent level effect of single level disc replacement systems have been reported in literature. The aim of this study was to compare the adjacent level biomechanics of bi-level disc replacement, bi-level fusion and a construct having adjoining level disc replacement and fusion system. In total, biomechanics of four models- intact, bi level disc replacement, bi level fusion and fusion plus disc replacement at adjoining levels- was studied to gain insight into the effects of various instrumentation systems on cranial and caudal adjacent levels using finite element analysis (73.6N+varying moment). The bi-level fusion models are more than twice as stiff as compared to the intact model during flexion-extension, lateral bending and axial rotation. Bi-level disc replacement model required moments lower than intact model (1.5Nm). Fusion plus disc replacement model required moment 10-25% more than intact model, except in extension. Adjacent level motions, facet loads and endplate stresses increased substantially in the bi-level fusion model. On the other hand, adjacent level motions, facet loads and endplate stresses were similar to intact for the bi-level disc replacement model. For the fusion plus disc replacement model, adjacent level motions, facet loads and endplate stresses were closer to intact model rather than the bi-level fusion model, except in extension. Based on our finite element analysis, fusion plus disc replacement procedure has less severe biomechanical effects on adjacent levels when compared to bi-level fusion procedure. Bi-level disc replacement procedure did not have any adverse mechanical effects on adjacent levels. Copyright © 2011 Elsevier Ltd. All rights reserved.

Growth factor release by vesicular phospholipid gels: in-vitro results and application for rotator cuff repair in a rat model.

PubMed

Buchmann, Stefan; Sandmann, Gunther H; Walz, Lars; Reichel, Thomas; Beitzel, Knut; Wexel, Gabriele; Tian, Weiwei; Battmann, Achim; Vogt, Stephan; Winter, Gerhard; Imhoff, Andreas B

2015-04-10

Biological augmentation of rotator cuff repair is of growing interest to improve biomechanical properties and prevent re-tearing. But intraoperative single shot growth factor application appears not sufficient to provide healing support in the physiologic growth factor expression peaks. The purpose of this study was to establish a sustained release of granulocyte-colony stimulating factor (G-CSF) from injectable vesicular phospholipid gels (VPGs) in vitro and to examine biocompatibility and influence on histology and biomechanical behavior of G-CSF loaded VPGs in a chronic supraspinatus tear rat model. G-CSF loaded VPGs were produced by dual asymmetric centrifugation. In vitro the integrity, stability and release rate were analyzed. In vivo supraspinatus tendons of 60 rats were detached and after 3 weeks a transosseous refixation with G-CSF loaded VPGs augmentation (n = 15; control, placebo, 1 and 10 μg G-CSF/d) was performed. 6 weeks postoperatively the healing site was analyzed histologically (n = 9; H&E by modified MOVIN score/Collagen I/III) and biomechanically (n = 6). In vitro testing revealed stable proteins after centrifugation and a continuous G-CSF release of up to 4 weeks. Placebo VPGs showed histologically no negative side effects on the healing process. Histologically in vivo testing demonstrated significant advantages for G-CSF 1 μg/d but not for G-CSF 10 μg/d in Collagen III content (p = 0.035) and a higher Collagen I/III ratio compared to the other groups. Biomechanically G-CSF 1 μg/d revealed a significant higher load to failure ratio (p = 0.020) compared to control but no significant differences in stiffness. By use of VPGs a continuous growth factor release could be obtained in vitro. The in vivo results demonstrate an improvement of immunohistology and biomechanical properties with a low dose G-CSF application via VPG. The VPG itself was well tolerated and had no negative influence on the healing behavior. Due to the favorable properties (highly adhesive, injectable, biocompatible) VPGs are a very interesting option for biologic augmentation. The study may serve as basis for further research in growth factor application models.

Acceleration and Orientation Jumping Performance Differences Among Elite Professional Male Handball Players With or Without Previous ACL Reconstruction: An Inertial Sensor Unit-Based Study.

PubMed

Setuain, Igor; González-Izal, Miriam; Alfaro, Jesús; Gorostiaga, Esteban; Izquierdo, Mikel

2015-12-01

Handball is one of the most challenging sports for the knee joint. Persistent biomechanical and jumping capacity alterations can be observed in athletes with an anterior cruciate ligament (ACL) injury. Commonly identified jumping biomechanical alterations have been described by the use of laboratory technologies. However, portable and easy-to-handle technologies that enable an evaluation of jumping biomechanics at the training field are lacking. To analyze unilateral/bilateral acceleration and orientation jumping performance differences among elite male handball athletes with or without previous ACL reconstruction via a single inertial sensor unit device. Case control descriptive study. At the athletes' usual training court. Twenty-two elite male (6 ACL-reconstructed and 16 uninjured control players) handball players were evaluated. The participants performed a vertical jump test battery that included a 50-cm vertical bilateral drop jump, a 20-cm vertical unilateral drop jump, and vertical unilateral countermovement jump maneuvers. Peak 3-dimensional (X, Y, Z) acceleration (m·s(-2)), jump phase duration and 3-dimensional orientation values (°) were obtained from the inertial sensor unit device. Two-tailed t-tests and a one-way analysis of variance were performed to compare means. The P value cut-off for significance was set at P < .05. The ACL-reconstructed male athletes did not show any significant (P < .05) residual jumping biomechanical deficits regarding the measured variables compared with players who had not suffered this knee injury. A dominance effect was observed among non-ACL reconstructed controls but not among their ACL-reconstructed counterparts (P < .05). Elite male handball athletes with previous ACL reconstruction demonstrated a jumping biomechanical profile similar to control players, including similar jumping performance values in both bilateral and unilateral jumping maneuvers, several years after ACL reconstruction. These findings are in agreement with previous research showing full functional restoration of abilities in top-level male athletes after ACL reconstruction, rehabilitation and subsequent return to sports at the previous level. Copyright © 2015 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

[Representation and mathematical analysis of human crystalline lens].

PubMed

Tălu, Stefan; Giovanzana, Stefano; Tălu, Mihai

2011-01-01

The surface of human crystalline lens can be described and analyzed using mathematical models based on parametric representations, used in biomechanical studies and 3D solid modeling of the lens. The mathematical models used in lens biomechanics allow the study and the behavior of crystalline lens on variables and complex dynamic loads. Also, the lens biomechanics has the potential to improve the results in the development of intraocular lenses and cataract surgery. The paper presents the most representative mathematical models currently used for the modeling of human crystalline lens, both optically and biomechanically.

Biomechanics of Interspinous Devices

PubMed Central

Parchi, Paolo D.; Evangelisti, Gisberto; Vertuccio, Antonella; Piolanti, Nicola; Andreani, Lorenzo; Cervi, Valentina; Giannetti, Christian; Calvosa, Giuseppe; Lisanti, Michele

2014-01-01

A number of interspinous devices (ISD) have been introduced in the lumbar spine implant market. Unfortunately, the use of these devices often is not associated with real comprehension of their biomechanical role. The aim of this paper is to review the biomechanical studies about interspinous devices available in the literature to allow the reader a better comprehension of the effects of these devices on the treated segment and on the adjacent segments of the spine. For this reason, our analysis will be limited to the interspinous devices that have biomechanical studies published in the literature. PMID:25114923

Effect of Anticipation on Lower Extremity Biomechanics During Side- and Cross-Cutting Maneuvers in Young Soccer Players.

PubMed

Kim, Jin Hyun; Lee, Ki-Kwang; Kong, Se Jin; An, Keun Ok; Jeong, Jin Hwa; Lee, Yong Seuk

2014-08-01

Less mature athletes exhibit biomechanical parameters during cutting maneuvers that may place these athletes at greater risk for injury than their more mature counterparts, especially if the maneuvers are unanticipated. However, most studies on risk factors for anterior cruciate ligament (ACL) injury have focused on neuromuscular and knee kinematic differences between the sexes, not on the biomechanical parameters between specific sporting maneuvers. (1) Anticipation will have a greater effect than the type of cutting maneuver (side- vs cross-cutting) in terms of the biomechanical risk factors for ACL injuries, and (2) the biomechanical risk factors will be different between the 2 types of maneuvers. Controlled laboratory study. Thirty-seven young, male middle school soccer players participated in this study. Three-dimensional motion analysis featuring ground-reaction force and electromyography of the right leg was used. Kinematics, kinetics, and electromyography data for each athlete were analyzed during anticipated and unanticipated side- and cross-cutting maneuvers. The differences between anticipated and unanticipated states as well as between side- and cross-cutting maneuvers were calculated and compared. After unanticipated side-cutting, the time to peak ground-reaction force was longer and peak values were smaller compared with anticipated side-cutting. Flexion, valgus, and internal rotations in the knee joint were larger, and greater flexion and valgus moments were observed. The vastus lateralis and vastus medialis showed lower activity, and the lateral gastrocnemius showed higher activity after unanticipated side-cutting maneuvers. With unanticipated cross-cutting, the time to peak ground-reaction force was longer and peak values were smaller compared with anticipated cross-cutting, and the lateral gastrocnemius showed higher activity. Differences in the peak values of the mediolateral and vertical forces were smaller in the cross-cutting maneuver than in side-cutting. Changes in flexion and adduction of the hip joint, flexion of the knee joint, and inversion of the ankle joint were larger during side-cutting. Although there were some interactions between direction and anticipation, anticipating a cutting maneuver generally had a greater effect than the type of maneuver when there was no significant interaction. Increases in the valgus angle and moment of the knee joint and higher lateral gastrocnemius activity during the late period showed an association with ACL injury risk factors during side-cutting, and higher lateral gastrocnemius activity during the early period showed an association with injury risk factors during cross-cutting. © 2014 The Author(s).

A Fibre-Reinforced Poroviscoelastic Model Accurately Describes the Biomechanical Behaviour of the Rat Achilles Tendon

PubMed Central

Heuijerjans, Ashley; Matikainen, Marko K.; Julkunen, Petro; Eliasson, Pernilla; Aspenberg, Per; Isaksson, Hanna

2015-01-01

Background Computational models of Achilles tendons can help understanding how healthy tendons are affected by repetitive loading and how the different tissue constituents contribute to the tendon’s biomechanical response. However, available models of Achilles tendon are limited in their description of the hierarchical multi-structural composition of the tissue. This study hypothesised that a poroviscoelastic fibre-reinforced model, previously successful in capturing cartilage biomechanical behaviour, can depict the biomechanical behaviour of the rat Achilles tendon found experimentally. Materials and Methods We developed a new material model of the Achilles tendon, which considers the tendon’s main constituents namely: water, proteoglycan matrix and collagen fibres. A hyperelastic formulation of the proteoglycan matrix enabled computations of large deformations of the tendon, and collagen fibres were modelled as viscoelastic. Specimen-specific finite element models were created of 9 rat Achilles tendons from an animal experiment and simulations were carried out following a repetitive tensile loading protocol. The material model parameters were calibrated against data from the rats by minimising the root mean squared error (RMS) between experimental force data and model output. Results and Conclusions All specimen models were successfully fitted to experimental data with high accuracy (RMS 0.42-1.02). Additional simulations predicted more compliant and soft tendon behaviour at reduced strain-rates compared to higher strain-rates that produce a stiff and brittle tendon response. Stress-relaxation simulations exhibited strain-dependent stress-relaxation behaviour where larger strains produced slower relaxation rates compared to smaller strain levels. Our simulations showed that the collagen fibres in the Achilles tendon are the main load-bearing component during tensile loading, where the orientation of the collagen fibres plays an important role for the tendon’s viscoelastic response. In conclusion, this model can capture the repetitive loading and unloading behaviour of intact and healthy Achilles tendons, which is a critical first step towards understanding tendon homeostasis and function as this biomechanical response changes in diseased tendons. PMID:26030436

The effect of locally delivered recombinant human bone morphogenetic protein-2 with hydroxyapatite/tri-calcium phosphate on the biomechanical properties of bone in diabetes-related osteoporosis.

PubMed

Liporace, Frank A; Breitbart, Eric A; Yoon, Richard S; Doyle, Erin; Paglia, David N; Lin, Sheldon

2015-06-01

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is particularly effective in improving osteogenesis in patients with diminished bone healing capabilities, such as individuals with type 1 diabetes mellitus (T1DM) who have impaired bone healing capabilities and increased risk of developing osteoporosis. This study measured the effects of rhBMP-2 treatment on osteogenesis by observing the dose-dependent effect of localized delivery of rhBMP-2 on biomechanical parameters of bone using a hydroxyapatite/tri-calcium phosphate (HA/TCP) carrier in a T1DM-related osteoporosis animal model. Two different doses of rhBMP-2 (LD low dose, HD high dose) with a HA/TCP carrier were injected into the femoral intramedullary canal of rats with T1DM-related osteoporosis. Two more diabetic rat groups were injected with saline alone and with HA/TCP carrier alone. Radiographs and micro-computed tomography were utilized for qualitative assessment of bone mineral density (BMD). Biomechanical testing occurred at 4- and 8-week time points; parameters tested included torque to failure, torsional rigidity, shear stress, and shear modulus. At the 4-week time point, the LD and HD groups both exhibited significantly higher BMD than controls; at the 8-week time point, the HD group exhibited significantly higher BMD than controls. Biomechanical testing revealed dose-dependent, higher trends in all parameters tested at the 4- and 8-week time points, with minimal significant differences. Groups treated with rhBMP-2 demonstrated improved bone mineral density at both 4 and 8 weeks compared to control saline groups, in addition to strong trends towards improvement of intrinsic and extrinsic biomechanical properties when compared to control groups. Data revealed trends toward dose-dependent increases in peak torque, torsional rigidity, shear stress, and shear modulus 4 weeks after rhBMP-2 treatment. Not applicable.

Development of custom measurement system for biomechanical evaluation of independent wheelchair transfers.

PubMed

Koontz, Alicia M; Lin, Yen-Sheng; Kankipati, Padmaja; Boninger, Michael L; Cooper, Rory A

2011-01-01

This study describes a new custom measurement system designed to investigate the biomechanics of sitting-pivot wheelchair transfers and assesses the reliability of selected biomechanical variables. Variables assessed include horizontal and vertical reaction forces underneath both hands and three-dimensional trunk, shoulder, and elbow range of motion. We examined the reliability of these measures between 5 consecutive transfer trials for 5 subjects with spinal cord injury and 12 nondisabled subjects while they performed a self-selected sitting pivot transfer from a wheelchair to a level bench. A majority of the biomechanical variables demonstrated moderate to excellent reliability (r > 0.6). The transfer measurement system recorded reliable and valid biomechanical data for future studies of sitting-pivot wheelchair transfers.We recommend a minimum of five transfer trials to obtain a reliable measure of transfer technique for future studies.

Biomechanical analysis of plate systems for proximal humerus fractures: a systematic literature review.

PubMed

Jabran, Ali; Peach, Chris; Ren, Lei

2018-04-27

Proximal humerus fractures are the third most common in the human body but their management remains controversial. Open reduction and internal fixation with plates is one of the leading modes of operative treatment for these fractures. The development of technologies and techniques for these plates, during the recent decades, promise a bright future for their clinical use. A comprehensive review of in vitro biomechanical studies is needed for the comparison of plates' mechanical performance and the testing methodologies. This will not only guide clinicians with plate selection but also with the design of future in vitro biomechanical studies. This review was aimed to systematically categorise and review the in vitro biomechanical studies of these plates based on their protocols and discuss their results. The technologies and techniques investigated in these studies were categorised and compared to reach a census where possible. Web of Science and Scopus database search yielded 62 studies. Out of these, 51 performed axial loading, torsion, bending and/or combined bending and axial loading while 11 simulated complex glenohumeral movements by using tendons. Loading conditions and set-up, failure criteria and performance parameters, as well as results for each study, were reviewed. Only two studies tested four-part fracture model while the rest investigated two- and three-part fractures. In ten studies, synthetic humeri were tested instead of cadaveric ones. In addition to load-displacement data, three-dimensional motion analysis systems, digital image correlation and acoustic emission testing have been used for measurement. Overall, PHILOS was the most tested plate and locking plates demonstrated better mechanical performance than non-locking ones. Conflicting results have been published for their comparison with non-locking blade plates and polyaxial locking screws. Augmentation with cement [calcium phosphate or poly(methyl methacrylate)] or allografts (fibular and femoral head) was found to improve bone-plate constructs' mechanical performance. Controversy still lies over the use of rigid and semi-rigid implants and the insertion of inferomedial screws for calcar region support. This review will guide the design of in vitro and in silico biomechanical tests and also supplement the study of clinical literature.

Comparison of completely knotless and hybrid double-row fixation systems: a biomechanical study.

PubMed

Chu, Thomas; McDonald, Erik; Tufaga, Michael; Kandemir, Utku; Buckley, Jenni; Ma, C Benjamin

2011-04-01

The purpose of this study was to compare the biomechanical performance of a completely knotless double-row repair system (SutureCross Knotless Anatomic Fixation System; KFx Medical, Carlsbad, CA) with 2 commonly used hybrid double-row repair (medial knot-tying, lateral knotless) systems (Bio-Corkscrew/PushLock [Arthrex, Naples, FL] and Spiralok/Versalok [DePuy Mitek, Raynham, MA]). Fourteen pairs of fresh-frozen cadaveric shoulders were harvested, the supraspinatus tendons were isolated, and full-thickness supraspinatus tears were created. One of each pair was repaired with the completely knotless system, and the contralateral side was repaired with either of the hybrid systems. The repairs were then subjected to cyclic loading followed by load to failure. Conditioning elongation, peak-to-peak elongation, ultimate load, and mechanism of failure were recorded and compared by use of paired t tests. Seven additional shoulders were tested to determine the effect of refrigeration storage on the completely knotless system by use of the same mechanical testing protocol. For the completely knotless repair group, 11 of 14 paired specimens failed during the cyclic loading period. Only 1 of 14 hybrid repair systems had failures during cyclic loading, and both hybrid repair systems had statistically lower conditioning elongation than the completely knotless repair group. The mean ultimate load of the SutureCross group was 166 ± 87 N, which was significantly lower than that in the Corkscrew/PushLock (310 ± 82 N) and Spiralok/Versalok (337 ± 44 N) groups. There was an effect of refrigeration storage on the peak-to-peak elongation and stiffness of the SutureCross group; however, there was no difference in ultimate tensile load or conditioning elongation. The completely knotless repair system has lower time-zero biomechanical properties than the other 2 hybrid systems. The SutureCross system has lower time-zero biomechanical properties when compared with other hybrid repair systems. Clinical outcome studies are needed to determine the significance. Copyright © 2011 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Dual mini-fragment plating for midshaft clavicle fractures: a clinical and biomechanical investigation.

PubMed

Prasarn, Mark L; Meyers, Kathleen N; Wilkin, Geoffrey; Wellman, David S; Chan, Daniel B; Ahn, Jaimo; Lorich, Dean G; Helfet, David L

2015-12-01

We sought to evaluate clinical and biomechanical outcomes of dual mini-fragment plate fixation for clavicle fractures. We hypothesized that this technique would produce an anatomical reduction with good clinical outcomes, be well tolerated by patients, and demonstrate equivalent biomechanics to single plating. Dual mini-fragment plating was performed for 17 isolated, displaced midshaft clavicle fractures. Functional outcomes and complications were retrospectively reviewed. A sawbones model compared dual plating biomechanics to a (1) superior 3.5-mm locking reconstruction plate, or (2) antero-inferior 3.5-mm locking reconstruction plate. On biomechanical testing, with anterior loading, dual plating was significantly more rigid than single locked anterior-plating (p = 0.02) but less rigid than single locked superior-plating (p = 0.001). With superior loading, dual plating trended toward higher rigidity versus single locked superior-plating (p = 0.07) but was less rigid than single locked anterior-plating (p = 0.03). No statistically significant differences in axial loading (p = 0.27) or torsion (p = 0.23) were detected. Average patient follow-up was 16.1 months (12-38). Anatomic reduction was achieved and maintained through final healing (average 14.7 weeks). No patient underwent hardware removal. Average 1-year DASH score was 4.0 (completed in 88 %). Displaced midshaft clavicle fractures can be effectively managed with dual mini-fragment plating. This technique results in high union rates and excellent clinical outcomes. Compared to single plating, dual plating is biomechanically equivalent in axial loading and torsion, yet offers better multi-planar bending stiffness despite the use of smaller plates. This technique may decrease the need for secondary surgery due to implant prominence and may aid in fracture reduction by buttressing butterfly fragments in two planes.

Biomechanical analysis comparing three C1-C2 transarticular screw salvaging fixation techniques.

PubMed

Elgafy, Hossein; Potluri, Tejaswy; Goel, Vijay K; Foster, Scott; Faizan, Ahmad; Kulkarni, Nikhil

2010-02-15

This is an in vitro biomechanical study. To compare the biomechanical stability of the 3 C1-C2 transarticular screw salvaging fixation techniques. Stabilization of the atlantoaxial complex is a challenging procedure because of its complicated anatomy. Many posterior stabilization techniques of the atlantoaxial complex have been developed with C1-C2 transarticular screw fixation been the current gold standard. The drawback of using the transarticular screws is that it has a potential risk of vertebral artery injury due to a high riding transverse foramen of C2 vertebra, and screw malposition. In such cases, it is not recommended to proceed with inserting the contralateral transarticular screw and the surgeon should find an alternative to fix the contralateral side. Many studies are available comparing different atlantoaxial stabilization techniques, but none of them compared the techniques to fix the contralateral side while using the transarticular screw on one side. The current options are C1 lateral mass screw and short C2 pedicle screw or C1 lateral mass screw and C2 intralaminar screw, or C1-C2 sublaminar wire. Nine fresh human cervical spines with intact ligaments (C0-C4) were subjected to pure moments in the 6 loading directions. The resulting spatial orientations of the vertebrae were recorded using an Optotrak 3-dimensional Motion Measurement System. Measurements were made sequentially for the intact spine after creating type II odontoid fracture and after stabilization with unilateral transarticular screw placement across C1-C2 (TS) supplemented with 1 of the 3 transarticular salvaging techniques on the contralateral side; C1 lateral mass screw and C2 pedicle screw (TS+C1LMS+C2PS), C1 lateral mass and C2 intralaminar screw (TS+C1LMS+C2ILS), or sublaminar wire (TS + wire). The data indicated that all the 3 stabilization techniques significantly decreased motion when compared to intact in all the loading cases (left/right lateral bending, left/right axial rotation, flexion) except extension. All the 3 instrumented specimens were equally stable in extension/flexion and lateral bending modes. TS+C1LMS+C2PS was equivalent to TS+C1LMS+C2ILS (P > 0.05) and superior to TS + wire in axial rotation (P < 0.05). Also, TS+C1LMS+C2ILS was superior to TS + wire in axial rotation (P < 0.05). Fixation of atlantoaxial complex using unilateral transarticular screw supplemented with contralateral C1 lateral mass and C2 intralaminar screws is biomechanically equivalent to C1 lateral mass and C2 pedicle screws and both are biomechanically superior to C1-C2 sublaminar wire in axial rotation.

Biomechanical effects of trees on soil and regolith: beyond treethrow

Treesearch

Jonathan D. Phillips; Daniel A. Marion

2006-01-01

Forest soils are profoundly influenced by the biomechanical as well as the chemical and biological effects of trees. Studies of biomechanical impacts have focused mainly on uprooting (treethrow), but this study shows that at least two other effects are significant: physical displacement of soil by root growth, and infilling of stump rot pits. Rocky soils in the...

Teaching undergraduate biomechanics with Just-in-Time Teaching.

PubMed

Riskowski, Jody L

2015-06-01

Biomechanics education is a vital component of kinesiology, sports medicine, and physical education, as well as for many biomedical engineering and bioengineering undergraduate programmes. Little research exists regarding effective teaching strategies for biomechanics. However, prior work suggests that student learning in undergraduate physics courses has been aided by using the Just-in-Time Teaching (JiTT). As physics understanding plays a role in biomechanics understanding, the purpose of study was to evaluate the use of a JiTT framework in an undergraduate biomechanics course. This two-year action-based research study evaluated three JiTT frameworks: (1) no JiTT; (2) mathematics-based JiTT; and (3) concept-based JiTT. A pre- and post-course assessment of student learning used the biomechanics concept inventory and a biomechanics concept map. A general linear model assessed differences between the course assessments by JiTT framework in order to evaluate learning and teaching effectiveness. The results indicated significantly higher learning gains and better conceptual understanding in a concept-based JiTT course, relative to a mathematics-based JiTT or no JiTT course structure. These results suggest that a course structure involving concept-based questions using a JiTT strategy may be an effective method for engaging undergraduate students and promoting learning in biomechanics courses.

Posterior Rigid Instrumentation of C7: Surgical Considerations and Biomechanics at the Cervicothoracic Junction. A Review of the Literature.

PubMed

Bayoumi, Ahmed B; Efe, Ibrahim E; Berk, Selim; Kasper, Ekkehard M; Toktas, Zafer Orkun; Konya, Deniz

2018-03-01

The cervicothoracic junction is a challenging anatomic transition in spine surgery. It is commonly affected by different types of diseases that may significantly impair stability in this region. The seventh cervical vertebra (C7) is an atypical cervical vertebra with unique anatomic features compared to subaxial cervical spine (C3 to C6). C7 has relatively broader laminae, larger pedicles, smaller lateral masses, and a long nonbifid spinous process. These features allow a variety of surgical methods for performing posterior rigid instrumentation in the form of different types of screws, such as lateral mass screws, pedicle screws, transfacet screws, and intralaminar screws. Many biomechanical studies on cadavers have evaluated and compared different types of implants at C7. We reviewed PubMed/Medline by using specific combinations of keywords to summarize previously published articles that examined C7 posterior rigid instrumentation thoroughly in an experimental fashion on patients or cadavers with additional descriptive radiologic parameters for evaluation of the optimum surgical technique for each type. A total of 44 articles were reported, including 22 articles that discussed anatomic considerations (entry points, sagittal and axial trajectories, and features of screws) and another 22 articles that discussed the relevant biomechanical testing at this transitional region if C7 was directly involved in terms of receiving posterior rigid implants. C7 can accommodate different types of screws, which can provide additional benefits and risks based on availability of bony purchase, awareness of surgical technique, biomechanics, and anatomic considerations. Copyright © 2017 Elsevier Inc. All rights reserved.

Comparison of histologic healing and biomechanical characteristics between repair techniques for a delaminated rotator cuff tear in rabbits.

PubMed

Cheon, Sang-Jin; Kim, Jung-Han; Gwak, Heui-Chul; Kim, Chang-Wan; Kim, Jeon-Kyo; Park, Ji-Hwan

2017-05-01

The purpose of this study was to compare histologic healing and biomechanical characteristics between 2 repair techniques (layer by layer, repair of each layer to bone separately; and whole layer, repair of each layer to the bone en masse) for delaminated rotator cuff tear. Rabbits were used as subjects and classified into 2 groups: group A, right side, the layer-by-layer repair group; and group B, left side, the whole-layer repair group. Histologic evaluations were done at 3 weeks (n = 7) and 6 weeks (n = 4) after operation. Biomechanical tests to evaluate the tensile property were done at time 0 (n = 5) and 3 weeks (n = 5) after operation. Histologic healing improved in all groups. A smaller cleft was found between layers in group B compared with the cleft in group A at 3 weeks after operation. At time 0, group A showed a higher yield load and ultimate failure load (67 ± 10.5 N and 80 ± 7.8 N, respectively). However, at 3 weeks after operation, group B showed a higher yield load (48 ± 7.6 N). In the delaminated rotator cuff tear model in the rabbit, the whole-layer repair showed a narrow gap between layers and a higher yield load at 3 weeks after operation. Surgical techniques that unite the cleft in a delaminated tear could improve biomechanical strength after operation. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Biomechanical Outcomes After Bio-enhanced Anterior Cruciate Ligament Repair and Anterior Cruciate Ligament Reconstruction Are Equal in a Porcine Model

PubMed Central

Vavken, Patrick; Fleming, Braden C.; Mastrangelo, Ashley N.; Machan, Jason T.; Murray, Martha M.

2011-01-01

Purpose The objective of this study was to compare the biomechanical outcomes of a new method of anterior cruciate ligament (ACL) treatment, bio-enhanced ACL repair, with ACL reconstruction in a large animal model. Methods Twenty-four skeletally immature pigs underwent unilateral ACL transection and were randomly allocated to receive bio-enhanced ACL repair with a collagen-platelet composite, allograft (bone–patellar tendon– bone) reconstruction, or no further treatment (n = 8 for each group). The structural properties and anteroposterior laxity of the experimental and contralateral ACL-intact knees were measured 15 weeks postoperatively. All dependent variables were normalized to those of the contralateral knee and compared by use of generalized linear mixed models. Results After 15 weeks, bio-enhanced ACL repair and ACL reconstruction produced superior biomechanical outcomes to ACL transection. However, there were no significant differences between bio-enhanced ACL repair and ACL reconstruction for maximum load (P = .4745), maximum displacement (P = .4217), or linear stiffness (P = .6327). There were no significant differences between the 2 surgical techniques in anteroposterior laxity at 30° (P = .7947), 60° (P = .6270), or 90° (P = .9008). Conclusions Bio-enhanced ACL repair produced biomechanical results that were not different from ACL reconstruction in a skeletally immature, large animal model, although the variability associated with both procedures was large. Both procedures produced significantly improved results over ACL transection, showing that both were effective in this model. Clinical Relevance Bio-enhanced ACL repair may 1 day provide an alternative treatment option for ACL injury. PMID:22261137

Comparative transcriptional analysis of three human ligaments with distinct biomechanical properties

PubMed Central

Lorda-Diez, Carlos I; Canga-Villegas, Ana; Cerezal, Luis; Plaza, Santiago; Hurlé, Juan M; García-Porrero, Juan A; Montero, Juan A

2013-01-01

One major aim of regenerative medicine targeting the musculoskeletal system is to provide complementary and/or alternative therapeutic approaches to current surgical therapies, often involving the removal and prosthetic substitution of damaged tissues such as ligaments. For these approaches to be successful, detailed information regarding the cellular and molecular composition of different musculoskeletal tissues is required. Ligaments have often been considered homogeneous tissues with common biomechanical properties. However, advances in tissue engineering research have highlighted the functional relevance of the organisational and compositional differences between ligament types, especially in those with higher risks of injury. The aim of this study was to provide information concerning the relative expression levels of a subset of key genes (including extracellular matrix components, transcription factors and growth factors) that confer functional identity to ligaments. We compared the transcriptomes of three representative human ligaments subjected to different biomechanical demands: the anterior cruciate ligament (ACL); the ligamentum teres of the hip (LT); and the iliofemoral ligament (IL). We revealed significant differences in the expression of type I collagen, elastin, fibromodulin, biglycan, transforming growth factor β1, transforming growth interacting factor 1, hypoxia-inducible factor 1-alpha and transforming growth factor β-induced gene between the IL and the other two ligaments. Thus, considerable molecular heterogeneity can exist between anatomically distinct ligaments with differing biomechanical demands. However, the LT and ACL were found to show remarkable molecular homology, suggesting common functional properties. This finding provides experimental support for the proposed role of the LT as a hip joint stabiliser in humans. PMID:24128114

Mesenchymal Stem Cell Therapy for the Treatment of Vocal Fold Scarring: A Systematic Review of Preclinical Studies

PubMed Central

Wingstrand, Vibe Lindeblad; Jensen, David H.; Bork, Kristian; Sebbesen, Lars; Balle, Jesper; Fischer-Nielsen, Anne; von Buchwald, Christian

2016-01-01

Objectives Therapy with mesenchymal stem cells exhibits potential for the development of novel interventions for many diseases and injuries. The use of mesenchymal stem cells in regenerative therapy for vocal fold scarring exhibited promising results to reduce stiffness and enhance the biomechanical properties of injured vocal folds. This study evaluated the biomechanical effects of mesenchymal stem cell therapy for the treatment of vocal fold scarring. Data Sources PubMed, Embase, the Cochrane Library and Google Scholar were searched. Methods Controlled studies that assessed the biomechanical effects of mesenchymal stem cell therapy for the treatment of vocal fold scarring were included. Primary outcomes were viscoelastic properties and mucosal wave amplitude. Results Seven preclinical animal studies (n = 152 single vocal folds) were eligible for inclusion. Evaluation of viscoelastic parameters revealed a decreased dynamic viscosity (η’) and elastic modulus (G’), i.e., decreased resistance and stiffness, in scarred vocal folds treated with mesenchymal stem cells compared to non-treated scarred vocal folds. Mucosal wave amplitude was increased in scarred vocal folds treated with mesenchymal stem cells vs. non-treated scarred vocal folds. Conclusion The results from these studies suggest an increased regenerative effect of therapy with mesenchymal stem cells for scarred vocal folds and are encouraging for further clinical studies. PMID:27631373

Mesenchymal Stem Cell Therapy for the Treatment of Vocal Fold Scarring: A Systematic Review of Preclinical Studies.

PubMed

Wingstrand, Vibe Lindeblad; Grønhøj Larsen, Christian; Jensen, David H; Bork, Kristian; Sebbesen, Lars; Balle, Jesper; Fischer-Nielsen, Anne; von Buchwald, Christian

2016-01-01

Therapy with mesenchymal stem cells exhibits potential for the development of novel interventions for many diseases and injuries. The use of mesenchymal stem cells in regenerative therapy for vocal fold scarring exhibited promising results to reduce stiffness and enhance the biomechanical properties of injured vocal folds. This study evaluated the biomechanical effects of mesenchymal stem cell therapy for the treatment of vocal fold scarring. PubMed, Embase, the Cochrane Library and Google Scholar were searched. Controlled studies that assessed the biomechanical effects of mesenchymal stem cell therapy for the treatment of vocal fold scarring were included. Primary outcomes were viscoelastic properties and mucosal wave amplitude. Seven preclinical animal studies (n = 152 single vocal folds) were eligible for inclusion. Evaluation of viscoelastic parameters revealed a decreased dynamic viscosity (η') and elastic modulus (G'), i.e., decreased resistance and stiffness, in scarred vocal folds treated with mesenchymal stem cells compared to non-treated scarred vocal folds. Mucosal wave amplitude was increased in scarred vocal folds treated with mesenchymal stem cells vs. non-treated scarred vocal folds. The results from these studies suggest an increased regenerative effect of therapy with mesenchymal stem cells for scarred vocal folds and are encouraging for further clinical studies.

Biomechanical characterization of decellularized and cross-linked bovine pericardium.

PubMed

Oswal, Dilip; Korossis, Sotirios; Mirsadraee, Saeed; Wilcox, Hilox; Watterson, Kevin; Fisher, John; Ingham, Eileen

2007-03-01

Although bovine pericardium has been used extensively in cardiothoracic surgery, its degeneration and calcification are important limiting factors in the continued use of this material. The study aims were to decellularize bovine pericardium and to compare the biomechanical properties of fresh and decellularized bovine pericardia to those treated with different concentrations of glutaraldehyde (GA). An established protocol for decellularization using sodium dodecyl sulfate was used, and histological analysis performed to validate the adequacy of decellularization. Contact cytotoxicity was used to study the in-vitro biocompatibility of variously treated pericardia. Mechanical testing involved uniaxial testing to failure. Mechanical properties of the fresh and decellularized pericardia (untreated and treated with 0.5% and 0.05% GA) were compared. Histological analysis of decellularized bovine pericardium did not show any remaining cells or cell fragments. The histoarchitecture of the collagen-elastin matrix appeared well preserved. Untreated decellularized pericardium was biocompatible in contact cytotoxicity tests with smooth muscle and fibroblast cells. The GA-treated tissue was cytotoxic. There were no significant differences in the mechanical properties of fresh and decellularized pericardia, but there was an overall tendency for GA-treated pericardia to be stiffer than their untreated counterparts. An acellular matrix, cross-linked with a reduced concentration of GA, can be produced using bovine pericardium. This biomaterial has excellent biomechanical properties and, potentially, may be used in the manufacture of heart valves and pericardial patches for clinical application.

Functional morphology and biomechanics of the tongue-bite apparatus in salmonid and osteoglossomorph fishes

PubMed Central

Camp, Ariel L; Konow, Nicolai; Sanford, Christopher P J

2009-01-01

The tongue-bite apparatus and its associated musculoskeletal elements of the pectoral girdle and neurocranium form the structural basis of raking, a unique prey-processing behaviour in salmonid and osteoglossomorph fishes. Using a quantitative approach, the functional osteology and myology of this system were compared between representatives of each lineage, i.e. the salmonid Salvelinus fontinalis (N =10) and the osteoglossomorph Chitala ornata(N = 8). Divergence was found in the morphology of the novel cleithrobranchial ligament, which potentially relates to kinematic differences between the raking lineage representatives. Salvelinus had greater anatomical cross-sectional areas of the epaxial, hypaxial and protractor hyoideus muscles, whereas Chitala had greater sternohyoideus and adductor mandibulae mass. Two osteology-based biomechanical models (a third-order lever for neurocranial elevation and a modified four-bar linkage for hyoid retraction) showed divergent force/velocity priorities in the study taxa. Salvelinus maximizes both force (via powerful cranial muscles) and velocity (through mechanical amplification) during raking. In contrast, Chitala has relatively low muscle force but more efficient force transmission through both mechanisms compared with Salvelinus. It remains unclear if and how behavioural modulation and specializations in the post-cranial anatomy may affect the force/velocity trade-offs in Chitala. Further studies of tongue-bite apparatus morphology and biomechanics in a broader species range may help to clarify the role that osteology and myology play in the evolution of behavioural diversity. PMID:19438765

Patterns in the knee flexion-extension moment profile during stair ascent and descent in patients with total knee arthroplasty.

PubMed

McClelland, Jodie A; Feller, Julian A; Menz, Hylton B; Webster, Kate E

2014-06-03

The aim of this study was to investigate the prevalence of abnormal knee biomechanical patterns in 40 patients with a modern TKA prosthesis, compared to 40 matched control participants when ascending and descending stairs. Fewer patients were able to ascend (65%) or descend stairs (53%) unassisted than controls (83%). Of the participants who could ascend and descend, cluster analysis classified most patients (up to 77%) as demonstrating a similar knee moment pattern as all controls. A small subgroup of patients who completed the tasks did so with distinctly abnormal biomechanics compared to other patients and controls. These findings suggest that recovery of normal stair climbing is possible. However, rehabilitation might be more effective if it were tailored to account for these differences between patients. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biomechanical effects of body weight support with a novel robotic walker for over-ground gait rehabilitation.

PubMed

Mun, Kyung-Ryoul; Lim, Su Bin; Guo, Zhao; Yu, Haoyong

2017-02-01

Body weight support (BWS) promotes better functional outcomes for neurologically challenged patients. Despite the established effectiveness of BWS in gait rehabilitation, the findings on biomechanical effects of BWS training still remain contradictory. Therefore, the aim of this study is to comprehensively investigate the effects of BWS. Using a newly developed robotic walker which can facilitate pelvic motions with an active BWS unit, we compared gait parameters of ten healthy subjects during a 10-m walk with incremental levels of body weight unloading, ranging from 0 to 40 % at 10 % intervals. Significant changes in joint angles and gait temporospatial parameters were observed. In addition, the results of an EMG signal study showed that the intensity of muscle activation was significantly reduced with increasing BWS levels. The reduction was found at the ankle, knee, and hip joints in the sagittal plane as well as at the hip joint in the frontal plane. The results of this study provide an important indication of increased lateral body balance and greater stabilization in sagittal and frontal plane during gait. Our findings provide a better understanding of the biomechanical effects of BWS during gait, which will help guide the gait rehabilitation strategies.

Biomechanical analyses of prolonged handwriting in subjects with and without perceived discomfort.

PubMed

Chang, Shao-Hsia; Chen, Chien-Liang; Yu, Nan-Ying

2015-10-01

Since wrist-joint position affects finger muscle length and grip strength, we studied its biomechanical relevance in prolonged handwriting. We recruited participants from young adults, aged 18-24, and separated them into control (n=22) and in-pain (n=18) groups, based whether or not they experience pain while handwriting. The participants then performed a writing task for 30 min on a computerized system which measured their wrist-joint angle and documented their handwriting kinematics. The in-pain group perceived more soreness and had a less-extended wrist joint, longer on-paper time, and slower stroke velocity compared to control group. There was no significant difference in handwriting speed and quality between the two groups. The wrist extension angle significantly correlated with perceived soreness. Ergonomic and biomechanical analyses provide important information about the handwriting process. Knowledge of pen tip movement kinematics and wrist-joint position can help occupational therapists plan treatment for individuals with handwriting induced pain. Copyright © 2015 Elsevier B.V. All rights reserved.

A comparison of four office chairs using biomechanical measures.

PubMed

Bush, Tamara Reid; Hubbard, Robert P

2008-08-01

The authors sought to use biomechanical measures, including motion and pressure, to compare four office chairs. The fit of a person to a chair is related to the geometric and kinematic compatibility between the two. This geometric compatibility influences the motions that are allowed or prohibited and the support pressures at the body-chair interface. Thus, during evaluation, it is necessary to treat the chair and user as a system. Four dynamic test conditions were evaluated with 14 participants of varying anthropometries. Test conditions were selected to compare the ability to accommodate primary and secondary motions (recline and spinal articulation) of seated occupants. The ability of a chair to allow recline, yet maintain head and hand positions, was compared across chairs. Also, the ability of each chair to allow and support spinal articulation was evaluated. Motion data for the chair, head, thorax, pelvis, and extremities were collected along with chair back pressures. Upon completion of testing, subjective assessments were also conducted. Statistically significant differences were found between chairs relative to head and hand motions. Also, significant differences were noted for the chairs' ability to move with the body during spinal articulation and the ability to provide support. Subjective assessments also yielded differences. Biomechanical analyses using motions and pressures can be conducted on office chairs with significant differences detected in their performance. Biomechanical assessments can be used to compare and contrast office chairs in terms that are relatable to fatigue reduction as well as operator performance.

Biomechanical Analysis of Porous Additive Manufactured Cages for Lateral Lumbar Interbody Fusion: A Finite Element Analysis.

PubMed

Zhang, Zhenjun; Li, Hui; Fogel, Guy R; Liao, Zhenhua; Li, Yang; Liu, Weiqiang

2018-03-01

A porous additive manufactured (AM) cage may provide stability similar to that of traditional solid cages and may be beneficial to bone ingrowth. The biomechanical influence of various porous cages on stability, subsidence, stresses in cage, and facet contact force has not been fully described. The purpose of this study was to verify biomechanical effects of porous AM cages. The surgical finite element models with various cages were constructed. The partially porous titanium (PPT) cages and fully porous titanium (FPT) cages were applied. The mechanical parameters of porous materials were obtained by mechanical test. Then the porous AM cages were compared with solid titanium (TI) cage and solid polyetheretherketone (PEEK) cage. The 4 motion modes were simulated. Range of motion (ROM), cage stress, end plate stress, and facet joint force (FJF) were compared. For all the surgical models, ROM decreased by >90%. Compared with TI and PPT cages, PEEK and FPT cages substantially reduced the maximum stresses in cage and end plate in all motion modes. Compared with PEEK cages, the stresses in cage and end plate for FPT cages decreased, whereas the ROM increased. Comparing FPT cages, the stresses in cage and end plate decreased with increasing porosity, whereas ROM increased with increasing porosity. After interbody fusion, FJF was substantially reduced in all motion modes except for flexion. Fully porous cages may offer an alternative to solid PEEK cages in lateral lumbar interbody fusion. However, it may be prudent to further increase the porosity of the cage. Copyright © 2017 Elsevier Inc. All rights reserved.

A Biomechanical Comparison of Distal Fixation for Bridge Plating in a Distal Radius Fracture Model.

PubMed

Alluri, Ram K; Bougioukli, Sofia; Stevanovic, Milan; Ghiassi, Alidad

2017-09-01

To compare the biomechanical properties of second versus third metacarpal distal fixation when using a radiocarpal spanning distraction plate in an unstable distal radius fracture model. Biomechanical evaluation of the radiocarpal spanning distraction plate comparing second versus third metacarpal distal fixation was performed using a standardized model of an unstable wrist fracture in 10 matched-pair cadaveric specimens. Each fixation construct underwent a controlled cyclic loading protocol in flexion and extension. The resultant displacement and stiffness were calculated at the fracture site. After cyclic loading, each specimen was loaded to failure. The stiffness, maximum displacement, and load to failure were compared between the 2 groups. Cyclic loading in flexion demonstrated that distal fixation to the third metacarpal resulted in greater stiffness compared with the second metacarpal. There was no significant difference between the 2 groups with regards to maximum displacement at the fracture site in flexion. Cyclic loading in extension demonstrated no significant difference in stiffness or maximum displacement between the 2 groups. The average load to failure was similar for both groups. Fixation to the third metacarpal resulted in greater stiffness in flexion. All other biomechanical parameters were similar when comparing distal fixation to the second or third metacarpal in distal radius fractures stabilized with a spanning internal distraction plate. The treating surgeon should choose distal metacarpal fixation primarily based on fracture pattern, alignment, and soft tissue integrity. If a stiffer construct is desired, placement of the radiocarpal spanning plate at the third metacarpal is preferred. Copyright © 2017 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Biomechanical comparison of graft fixation at 30° and 90° of elbow flexion for ulnar collateral ligament reconstruction by the docking technique.

PubMed

Cohen, Steven B; Woods, Daniel P; Siegler, Sorin; Dodson, Christopher C; Namani, Ramya; Ciccotti, Michael G

2015-02-01

Ulnar collateral ligament (UCL) injuries have been successfully treated by the docking reconstruction. Although fixation of the graft has been suggested at 30° of elbow flexion, no quantitative biomechanical data exist to provide guidelines for the optimal elbow flexion angle for graft fixation. Testing was conducted on 10 matched pairs of cadaver elbows with use of a loading system and optoelectric tracking device. After biomechanical data on the native UCL were obtained, reconstruction by the docking technique was performed with use of palmaris longus autograft with one elbow fixated at 30° and the contralateral elbow at 90° of elbow flexion. Biomechanical testing was undertaken on these specimens. The load to failure of the native UCL (mean, 20.1 N-m) was significantly higher (P = .004) than that of the reconstructed UCL (mean, 4.6 N-m). There was no statistically significant difference in load to failure of the UCL reconstructions fixated at 30° of elbow flexion (average, 4.86 N-m) compared with those at 90° (average, 4.35 N-m). Elbows reconstructed at 30° and 90° of elbow flexion produced similar kinematic coupling and valgus laxity characteristics compared with each other and with the intact UCL. Although not statistically significant, the reconstructions fixated at 30° more closely resembled the biomechanical characteristics of the intact elbow than did reconstructions fixated at 90°. No statistically significant difference was found in comparing the docking technique of UCL reconstruction with graft fixation at 30° vs. 90° of elbow flexion. Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Biochemical, histologic, and biomechanical characterization of native and decellularized flexor tendon specimens harvested from the pelvic limbs of orthopedically normal dogs.

PubMed

Balogh, Daniel G; Biskup, Jeffery J; O'Sullivan, M Gerard; Scott, Ruth M; Groschen, Donna; Evans, Richard B; Conzemius, Michael G

2016-04-01

To evaluate the biochemical and biomechanical properties of native and decellularized superficial digital flexor tendons (SDFTs) and deep digital flexor tendons (DDFTs) harvested from the pelvic limbs of orthopedically normal dogs. 22 commercially supplied tendon specimens (10 SDFT and 12 DDFT) harvested from the pelvic limbs of 13 canine cadavers. DNA, glycosaminoglycan, collagen, and protein content were measured to biochemically compare native and decellularized SDFT and DDFT specimens. Mechanical testing was performed on 4 groups consisting of native tendons (5 SDFTs and 6 DDFTs) and decellularized tendons (5 SDFTs and 6 DDFTs). All tendons were preconditioned, and tension was applied to failure at 0.5 mm/s. Failure mode was video recorded for each tendon. Load-deformation and stress-strain curves were generated; calculations were performed to determine the Young modulus and stiffness. Biochemical and biomechanical data were statistically compared by use of the Wilcoxon rank sum test. Decellularized SDFT and DDFT specimens had significantly less DNA content than did native tendons. No significant differences were identified between native and decellularized specimens with respect to glycosaminoglycan, collagen, or protein content. Biomechanical comparison yielded no significant intra- or intergroup differences. All DDFT constructs failed at the tendon-clamp interface, whereas nearly half (4/10) of the SDFT constructs failed at midsubstance. Decellularized commercial canine SDFT and DDFT specimens had similar biomechanical properties, compared with each other and with native tendons. The decellularization process significantly decreased DNA content while minimizing loss of extracellular matrix components. Decellularized canine flexor tendons may provide suitable, biocompatible graft scaffolds for bioengineering applications such as tendon or ligament repair.

Lower Extremity Energy Absorption and Biomechanics During Landing, Part II: Frontal-Plane Energy Analyses and Interplanar Relationships

PubMed Central

Norcross, Marc F.; Lewek, Michael D.; Padua, Darin A.; Shultz, Sandra J.; Weinhold, Paul S.; Blackburn, J. Troy

2013-01-01

Context: Greater sagittal-plane energy absorption (EA) during the initial impact phase (INI) of landing is consistent with sagittal-plane biomechanics that likely increase anterior cruciate ligament (ACL) loading, but it does not appear to influence frontal-plane biomechanics. We do not know whether frontal-plane INI EA is related to high-risk frontal-plane biomechanics. Objective: To compare biomechanics among INI EA groups, determine if women are represented more in the high group, and evaluate interplanar INI EA relationships. Design: Descriptive laboratory study. Setting: Research laboratory. Patients or Other Participants: Participants included 82 (41 men, 41 women; age = 21.0 ± 2.4 years, height = 1.74 ± 0.10 m, mass = 70.3 ± 16.1 kg) healthy, physically active volunteers. Intervention(s): We assessed landing biomechanics with an electromagnetic motion-capture system and force plate. Main Outcome Measure(s): We calculated frontal- and sagittal-plane total, hip, knee, and ankle INI EA. Total frontal-plane INI EA was used to create high, moderate, and low tertiles. Frontal-plane knee and hip kinematics, peak vertical and posterior ground reaction forces, and peak internal knee-varus moment (pKVM) were identified and compared across groups using 1-way analyses of variance. We used a χ2 analysis to evaluate male and female allocation to INI EA groups. We used simple, bivariate Pearson product moment correlations to assess interplanar INI EA relationships. Results: The high–INI EA group exhibited greater knee valgus at ground contact, hip adduction at pKVM, and peak hip adduction than the low–INI EA group (P < .05) and greater peak knee valgus, pKVM, and knee valgus at pKVM than the moderate– (P < .05) and low– (P < .05) INI EA groups. Women were more likely than men to be in the high–INI EA group (χ2 = 4.909, P = .03). Sagittal-plane knee and frontal-plane hip INI EA (r = 0.301, P = .006) and sagittal-plane and frontal-plane ankle INI EA were associated (r = 0.224, P = .04). No other interplanar INI EA relationships were found (P > .05). Conclusions: Greater frontal-plane INI EA was associated with less favorable frontal-plane biomechanics that likely result in greater ACL loading. Women were more likely than men to use greater frontal-plane INI EA. The magnitudes of sagittal- and frontal-plane INI EA were largely independent. PMID:23944381

FEBio: finite elements for biomechanics.

PubMed

Maas, Steve A; Ellis, Benjamin J; Ateshian, Gerard A; Weiss, Jeffrey A

2012-01-01

In the field of computational biomechanics, investigators have primarily used commercial software that is neither geared toward biological applications nor sufficiently flexible to follow the latest developments in the field. This lack of a tailored software environment has hampered research progress, as well as dissemination of models and results. To address these issues, we developed the FEBio software suite (http://mrl.sci.utah.edu/software/febio), a nonlinear implicit finite element (FE) framework, designed specifically for analysis in computational solid biomechanics. This paper provides an overview of the theoretical basis of FEBio and its main features. FEBio offers modeling scenarios, constitutive models, and boundary conditions, which are relevant to numerous applications in biomechanics. The open-source FEBio software is written in C++, with particular attention to scalar and parallel performance on modern computer architectures. Software verification is a large part of the development and maintenance of FEBio, and to demonstrate the general approach, the description and results of several problems from the FEBio Verification Suite are presented and compared to analytical solutions or results from other established and verified FE codes. An additional simulation is described that illustrates the application of FEBio to a research problem in biomechanics. Together with the pre- and postprocessing software PREVIEW and POSTVIEW, FEBio provides a tailored solution for research and development in computational biomechanics.

Biomechanics of Ergometric Stress Test: regional and local effects on elastic, transitional and muscular human arteries

NASA Astrophysics Data System (ADS)

Valls, G.; Torrado, J.; Farro, I.; Bia, D.; Zócalo, Y.; Lluberas, S.; Craiem, D.; Armentano, Rl

2011-09-01

Ergometric exercise stress tests (EST) give important information about the cardiovascular (CV) response to increased demands. The expected EST-related changes in variables like blood pressure and heart rate are known, but those in the arterial biomechanics are controversial and incompletely characterized. In this context, this work aims were to characterize the regional and local arterial biomechanical behaviour in response to EST; to evaluate its temporal profile in the post-EST recovery phase; and to compare the biomechanical response of different to EST. Methods: In 16 non-trained healthy young subjects the carotid-femoral pulse wave velocity and the carotid, femoral and brachial arterial distensibility were non-invasively evaluated before (Rest) and after EST. Main results: The EST resulted in an early increase in the arterial stiffness, evidenced by both, regional and local parameters (pulse wave velocity increase and distensibility reduction). When analyzing conjunctly the different post-EST recovery stages there were quali-quantitative differences among the arterial local stiffness response to EST. The biomechanical changes could not be explained only by blood pressure variations.

Biomechanical comparison of reverse total shoulder arthroplasty systems in soft tissue-constrained shoulders.

PubMed

Henninger, Heath B; King, Frank K; Tashjian, Robert Z; Burks, Robert T

2014-05-01

Numerous studies have examined the biomechanics of isolated variables in reverse total shoulder arthroplasty. This study directly compared the composite performance of two reverse total shoulder arthroplasty systems; each system was designed around either a medialized or a lateralized glenohumeral center of rotation. Seven pairs of shoulders were tested on a biomechanical simulator. Center of rotation, position of the humerus, passive and active range of motion, and force to abduct the arm were quantified. Native arms were tested, implanted with a Tornier Aequalis or DJO Surgical Reverse Shoulder Prosthesis (RSP), and then retested. Differences from the native state were then documented. Both systems shifted the center of rotation medially and inferiorly relative to native. Medial shifts were greater in the Aequalis implant (P < .037). All humeri shifted inferior compared with native but moved medially with the Aequalis (P < .001). Peak passive abduction, internal rotation, and external rotation did not differ between systems (P > .05). Both reverse total shoulder arthroplasty systems exhibited adduction deficits, but the RSP implant deficit was smaller (P = .046 between implants). Both systems reduced forces to abduct the arm compared with native, although the Aequalis required more force to initiate motion from the resting position (P = .022). Given the differences in system designs and configurations, outcome variables were generally comparable. The RSP implant allowed slightly more adduction, had a more lateralized humeral position, and required less force to initiate elevation. These factors may play roles in limiting scapular notching, improving active external rotation by normalizing the residual rotator cuff length, and limiting excessive stress on the deltoid. Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

Reverse engineering of mandible and prosthetic framework: Effect of titanium implants in conjunction with titanium milled full arch bridge prostheses on the biomechanics of the mandible.

PubMed

De Santis, Roberto; Gloria, Antonio; Russo, Teresa; D'Amora, Ugo; Varriale, Angelo; Veltri, Mario; Balleri, Piero; Mollica, Francesco; Riccitiello, Francesco; Ambrosio, Luigi

2014-12-18

This study aimed at investigating the effects of titanium implants and different configurations of full-arch prostheses on the biomechanics of edentulous mandibles. Reverse engineered, composite, anisotropic, edentulous mandibles made of a poly(methylmethacrylate) core and a glass fibre reinforced outer shell were rapid prototyped and instrumented with strain gauges. Brånemark implants RP platforms in conjunction with titanium Procera one-piece or two-piece bridges were used to simulate oral rehabilitations. A lateral load through the gonion regions was used to test the biomechanical effects of the rehabilitations. In addition, strains due to misfit of the one-piece titanium bridge were compared to those produced by one-piece cast gold bridges. Milled titanium bridges had a better fit than cast gold bridges. The stress distribution in mandibular bone rehabilitated with a one-piece bridge was more perturbed than that observed with a two-piece bridge. In particular the former induced a stress concentration and stress shielding in the molar and symphysis regions, while for the latter design these stresses were strongly reduced. In conclusion, prosthetic frameworks changed the biomechanics of the mandible as a result of both their design and manufacturing technology. Copyright © 2014 Elsevier Ltd. All rights reserved.

Masticatory biomechanics in the rabbit: a multi-body dynamics analysis.

PubMed

Watson, Peter J; Gröning, Flora; Curtis, Neil; Fitton, Laura C; Herrel, Anthony; McCormack, Steven W; Fagan, Michael J

2014-10-06

Multi-body dynamics is a powerful engineering tool which is becoming increasingly popular for the simulation and analysis of skull biomechanics. This paper presents the first application of multi-body dynamics to analyse the biomechanics of the rabbit skull. A model has been constructed through the combination of manual dissection and three-dimensional imaging techniques (magnetic resonance imaging and micro-computed tomography). Individual muscles are represented with multiple layers, thus more accurately modelling muscle fibres with complex lines of action. Model validity was sought through comparing experimentally measured maximum incisor bite forces with those predicted by the model. Simulations of molar biting highlighted the ability of the masticatory system to alter recruitment of two muscle groups, in order to generate shearing or crushing movements. Molar shearing is capable of processing a food bolus in all three orthogonal directions, whereas molar crushing and incisor biting are predominately directed vertically. Simulations also show that the masticatory system is adapted to process foods through several cycles with low muscle activations, presumably in order to prevent rapidly fatiguing fast fibres during repeated chewing cycles. Our study demonstrates the usefulness of a validated multi-body dynamics model for investigating feeding biomechanics in the rabbit, and shows the potential for complementing and eventually reducing in vivo experiments.

Masticatory biomechanics in the rabbit: a multi-body dynamics analysis

PubMed Central

Watson, Peter J.; Gröning, Flora; Curtis, Neil; Fitton, Laura C.; Herrel, Anthony; McCormack, Steven W.; Fagan, Michael J.

2014-01-01

Multi-body dynamics is a powerful engineering tool which is becoming increasingly popular for the simulation and analysis of skull biomechanics. This paper presents the first application of multi-body dynamics to analyse the biomechanics of the rabbit skull. A model has been constructed through the combination of manual dissection and three-dimensional imaging techniques (magnetic resonance imaging and micro-computed tomography). Individual muscles are represented with multiple layers, thus more accurately modelling muscle fibres with complex lines of action. Model validity was sought through comparing experimentally measured maximum incisor bite forces with those predicted by the model. Simulations of molar biting highlighted the ability of the masticatory system to alter recruitment of two muscle groups, in order to generate shearing or crushing movements. Molar shearing is capable of processing a food bolus in all three orthogonal directions, whereas molar crushing and incisor biting are predominately directed vertically. Simulations also show that the masticatory system is adapted to process foods through several cycles with low muscle activations, presumably in order to prevent rapidly fatiguing fast fibres during repeated chewing cycles. Our study demonstrates the usefulness of a validated multi-body dynamics model for investigating feeding biomechanics in the rabbit, and shows the potential for complementing and eventually reducing in vivo experiments. PMID:25121650

Biomechanical Assessment of the Canadian Integrated Load Carriage System using Objective Assessment Measures

DTIC Science & Technology

2001-05-01

UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADPO 11004 TITLE: Biomechanical Assessment of the Canadian Integrated Load...ADP010987 thru ADPO11009 UNCLASSIFIED 21-1 Biomechanical Assessment of the Canadian Integrated Load Carriage System using Objective Assessment Measures Joan...CANADA, B3J 2X4 Summary The purpose of this study was to provide an overview of contributions by biomechanical testing to the design of the final

Construction and validation of a three-dimensional finite element model of degenerative scoliosis.

PubMed

Zheng, Jie; Yang, Yonghong; Lou, Shuliang; Zhang, Dongsheng; Liao, Shenghui

2015-12-24

With the aging of the population, degenerative scoliosis (DS) incidence rate is increasing. In recent years, increasing research on this topic has been carried out, yet biomechanical research on the subject is seldom seen and in vitro biomechanical model of DS nearly cannot be available. The objective of this study was to develop and validate a complete three-dimensional finite element model of DS in order to build the digital platform for further biomechanical study. A 55-year-old female DS patient (Suer Pan, ID number was P141986) was selected for this study. This study was performed in accordance with the ethical standards of Declaration of Helsinki and its amendments and was approved by the local ethics committee (117 hospital of PLA ethics committee). Spiral computed tomography (CT) scanning was conducted on the patient's lumbar spine from the T12 to S1. CT images were then imported into a finite element modeling system. A three-dimensional solid model was then formed from segmentation of the CT scan. The three-dimensional model of each vertebra was then meshed, and material properties were assigned to each element according to the pathological characteristics of DS. Loads and boundary conditions were then applied in such a manner as to simulate in vitro biomechanical experiments conducted on lumbar segments. The results of the model were then compared with experimental results in order to validate the model. An integral three-dimensional finite element model of DS was built successfully, consisting of 113,682 solid elements, 686 cable elements, 33,329 shell elements, 4968 target elements, 4968 contact elements, totaling 157,635 elements, and 197,374 nodes. The model accurately described the physical features of DS and was geometrically similar to the object of study. The results of analysis with the finite element model agreed closely with in vitro experiments, validating the accuracy of the model. The three-dimensional finite element model of DS built in this study is clear, reliable, and effective for further biomechanical simulation study of DS.

Development of custom measurement system for biomechanical evaluation of independent wheelchair transfers

PubMed Central

Koontz, Alicia M.; Lin, Yen-Sheng; Kankipati, Padmaja; Boninger, Michael L.; Cooper, Rory A.

2017-01-01

This study describes a new custom measurement system designed to investigate the biomechanics of sitting-pivot wheelchair transfers and assesses the reliability of selected biomechanical variables. Variables assessed include horizontal and vertical reaction forces underneath both hands and three-dimensional trunk, shoulder, and elbow range of motion. We examined the reliability of these measures between 5 consecutive transfer trials for 5 subjects with spinal cord injury and 12 non-disabled subjects while they performed a self-selected sitting pivot transfer from a wheelchair to a level bench. A majority of the biomechanical variables demonstrated moderate to excellent reliability (r > 0.6). The transfer measurement system recorded reliable and valid biomechanical data for future studies of sitting-pivot wheelchair transfers. We recommend a minimum of five transfer trials to obtain a reliable measure of transfer technique for future studies. PMID:22068376

Restoration of labral anatomy and biomechanics after superior labral anterior-posterior repair: comparison of mattress versus simple technique.

PubMed

Boddula, Madhav R; Adamson, Gregory J; Gupta, Akash; McGarry, Michelle H; Lee, Thay Q

2012-04-01

Both simple and mattress repair techniques have been utilized with success for type II superior labral anterior-posterior (SLAP) lesions; however, direct anatomic and biomechanical comparisons of these techniques have yet to be clearly demonstrated. For type II SLAP lesions, the mattress suture repair technique will result in greater labral height and better position on the glenoid face and exhibit stronger biomechanical characteristics, when cyclically loaded and loaded to failure through the biceps, compared with the simple suture repair technique. Controlled laboratory study. Six matched pairs of cadaveric shoulders were dissected, and a clock face was created on the glenoid from 9 o'clock (posterior) to 3 o'clock (anterior). For the intact specimen, labral height and labral distance from the glenoid edge were measured using a MicroScribe. A SLAP lesion was then created from 10 o'clock to 2 o'clock. Lesions were repaired with two 3.0-mm BioSuture-Tak anchors placed at 11 o'clock and 1 o'clock. For each pair, a mattress repair was used for one shoulder, and a simple repair was used for the contralateral shoulder. After repair, labral height and labral distance from the glenoid edge were again measured. The specimens were then cyclically loaded and loaded to failure through the biceps using an Instron machine. A paired t test was used for statistical analysis. After mattress repair, a significant increase in labral height occurred compared with intact from 2.5 ± 0.3 mm to 4.3 ± 0.3 mm at 11 o'clock (P = .013), 2.7 ± 0.5 mm to 4.2 ± 0.7 mm at 12:30 o'clock (P = .007), 3.1 ± 0.5 mm to 4.2 ± 0.7 mm at 1 o'clock (P = .006), and 2.8 ± 0.7 mm to 3.7 ± 0.8 mm at 1:30 o'clock (P = .037). There was no significant difference in labral height between the intact condition and after simple repair at any clock face position. Labral height was significantly increased in the mattress repairs compared with simple repairs at 11 o'clock (mean difference, 2.0 mm; P = .008) and 12:30 o'clock (mean difference, 1.3 mm; P = .044). Labral distance from the glenoid edge was not significantly different between techniques. No difference was observed between the mattress and simple repair techniques for all biomechanical parameters, except the simple technique had a higher load and energy absorbed at 2-mm displacement. The mattress technique created a greater labral height while maintaining similar biomechanical characteristics compared with the simple repair, with the exception of load and energy absorbed at 2-mm displacement, which was increased for the simple technique. Mattress repair for type II SLAP lesions creates a higher labral bumper compared with simple repairs, while both techniques resulted in similar biomechanical characteristics.

A Biomechanical Analysis of Different Clavicular Tunnel Diameters in Anatomic Acromioclavicular Ligament Reconstruction.

PubMed

Voss, Andreas; Beitzel, Knut; Alaee, Farhang; Dukas, Alex; Herbst, Elmar; Obopilwe, Elifho; Apostolakos, John; DiVenere, Jessica; Singh, Hardeep; Cote, Mark P; Mazzocca, Augustus D

2016-08-01

To evaluate the biomechanical stability of a tendon-to-clavicle bone interface fixation of a graft in revision acromioclavicular reconstruction. Fifteen fresh-frozen cadaveric shoulders were used. All specimens underwent bone density evaluation. For the primary reconstruction, a 5-mm semitendinosus allograft was inserted into a 5-mm bone tunnel at 25 and 45 mm from the lateral end of the clavicle using a 5.5 × 8-mm PEEK (polyether ether ketone) tenodesis screw. Each single graft was fixed in a cryo-clamp and cyclically loaded from 5 to 70 N for 3,000 cycles, followed by load-to-failure testing at a rate of 120 mm/min to simulate the revision case. To simulate tunnel widening, the tunnels of the revision series were over-drilled with an 8-mm drill, and a 5-mm semitendinosus graft with an 8 × 12-mm PEEK tenodesis screw was inserted. Biomechanical testing was then repeated. The bone mineral density analysis showed a significantly higher density at the 45-mm hole compared with the 25-mm hole (P = .001). The ultimate load to failure increased from the 5.5-mm screw to the 8-mm screw at the 45-mm hole position (P = .001). There was no statistically significant difference at the 25-mm hole position (P = .934). No statistical significance for graft elongation comparing the 5.5-mm screw and the 8-mm screw at the 25-mm (P = .156) and 45-mm (P = .334) positions could be found. Comparable biomechanical stability for the tendon-to-bone interface fixation in different clavicular tunnel diameters simulating primary and revision reconstruction was achieved. There is a lack of literature regarding revision acromioclavicular joint reconstruction, but our biomechanical results show comparable stability to primary reconstruction. These data provide support for the use of anatomic acromioclavicular ligament reconstruction in revision cases. Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

What Factors Influence the Biomechanical Properties of Allograft Tissue for ACL Reconstruction? A Systematic Review.

PubMed

Lansdown, Drew A; Riff, Andrew J; Meadows, Molly; Yanke, Adam B; Bach, Bernard R

2017-10-01

Allograft tissue is used in 22% to 42% of anterior cruciate ligament (ACL) reconstructions. Clinical outcomes have been inconsistent with allograft tissue, with some series reporting no differences in outcomes and others reporting increased risk of failure. There are numerous variations in processing and preparation that may influence the eventual performance of allograft tissue in ACL reconstruction. We sought to perform a systematic review to summarize the factors that affect the biomechanical properties of allograft tissue for use in ACL reconstruction. Many factors might impact the biomechanical properties of allograft tissue, and these should be understood when considering using allograft tissue or when reporting outcomes from allograft reconstruction. What factors affect the biomechanical properties of allograft tissue used for ACL reconstruction? We performed a systematic review to identify studies on factors that influence the biomechanical properties of allograft tissue through PubMed and SCOPUS databases. We included cadaveric and animal studies that reported on results of biomechanical testing, whereas studies on fixation, histologic evaluation, and clinical outcomes were excluded. There were 319 unique publications identified through the search with 48 identified as relevant to answering the study question. For each study, we recorded the type of tissue tested, parameters investigated, and the effects on biomechanical behavior, including load to failure and stiffness. Primary factors identified to influence allograft tissue properties were graft tissue type, sterilization methods (irradiation and chemical processing), graft preparation, donor parameters, and biologic adjuncts. Load to failure and graft stiffness varied across different tissue types, with nonlooped tibialis grafts exhibiting the lowest values. Studies on low-dose irradiation showed variable effects, whereas high-dose irradiation consistently produced decreased load to failure and stiffness values. Various chemical sterilization measures were also associated with negative effects on biomechanical properties. Prolonged freezing decreased load to failure, ultimate stress, and ultimate strain. Up to eight freeze-thaw cycles did not lead to differences in biomechanical properties of cadaveric grafts. Regional differences were noted in patellar tendon grafts, with the central third showing the highest load to failure and stiffness. Graft diameter strongly contributed to load-to-failure measurements. Age older than 40 years, and especially older than 65 years, negatively impacted biomechanical properties, whereas gender had minimal effect on the properties of allograft tissue. Biologic adjuncts show potential for improving in vivo properties of allograft tissue. Future clinical studies on allograft ACL reconstruction should investigate in vivo graft performance with standardized allograft processing and preparation methods that limit the negative effects on the biomechanical properties of tissue. Additionally, biologic adjuncts may improve the biomechanical properties of allograft tissue, although future preclinical and clinical studies are necessary to clarify the role of these treatments. Based on the findings of this systematic review that emphasize biomechanical properties of ACL allografts, surgeons should favor the use of central third patellar tendon or looped soft tissue grafts, maximize graft cross-sectional area, and favor grafts from donors younger than 40 years of age while avoiding grafts subjected to radiation doses > 20 kGy, chemical processing, or greater than eight freeze-thaw cycles.

Effects of a Program for Improving Biomechanical Characteristics During Walking and Running in Children Who Are Obese.

PubMed

Steinberg, Nili; Rubinstein, Meron; Nemet, Dan; Ayalon, Moshe; Zeev, Aviva; Pantanowitz, Michal; Brosh, Tamar; Eliakim, Alon

2017-10-01

To investigate the influence of a weight-reduction program with locomotion-emphasis on improving biomechanical characteristics of children who are obese (OW). Ten children who are OW participated in a 6-month multidisciplinary childhood obesity management program (GRP1); another 10 children who are OW participated in the same multidisciplinary childhood obesity management program with additional locomotion-emphasis exercises for improving biomechanical characteristics (GRP2); and 10 control children who are OW with no intervention program. Outcomes were anthropometric measurements and temporal and foot pressure parameters. GRP2 had significantly improved foot pressure in the different walking/running speeds compared with GRP1. In the temporal parameters, pretests by speed by group interactions were significantly improved for GRP2 compared with GRP1. We found evidence to support beneficial effects of combined dietary and physical activity/locomotion-emphasis exercises on the movement characteristics of children who are OW.

Sex differences in lower extremity biomechanics during single leg landings.

PubMed

Schmitz, Randy J; Kulas, Anthony S; Perrin, David H; Riemann, Bryan L; Shultz, Sandra J

2007-07-01

Females have an increased incident rate of anterior cruciate ligament tears compared to males. Biomechanical strategies to decelerate the body in the vertical direction have been implicated as a contributing cause. This study determined if females would exhibit single leg landing strategies characterized by decreased amounts of hip, knee, and ankle flexion resulting in greater vertical ground reaction forces and altered energy absorption patterns when compared to males. Recreationally active males (N=14) and females (N=14), completed five single leg landings from a 0.3m height onto a force platform while three-dimensional kinematics and kinetics were simultaneously collected. Compared to males, females exhibited (1) less total hip and knee flexion displacements (40% and 64% of males, respectively, P<0.05) and less time to peak hip and knee flexion (48% and 78% of males, respectively, P<0.05), (2) 9% greater peak vertical ground reaction forces (P<0.05), (3) less total lower body energy absorption (76% of males, P<0.05), and (4) 11% greater relative energy absorption at the ankle (P<0.05). Females in this study appear to adopt a single leg landing style using less hip and knee flexion, absorbing less total lower body energy with more relative energy at the ankle resulting in a landing style that can be described as stiff. This may potentially cause increased demands on non-contractile components of the lower extremity. Preventative training programs designed to prevent knee injury may benefit from the biomechanical description of sex-specific landing methods demonstrated by females in this study by focusing on the promotion of more reliance on using the contractile components to absorb impact energy during landings.

Patients With Insertional Achilles Tendinopathy Exhibit Differences in Ankle Biomechanics as Opposed to Strength and Range of Motion.

PubMed

Chimenti, Ruth L; Flemister, A Samuel; Tome, Joshua; McMahon, James M; Houck, Jeff R

2016-12-01

Study Design Controlled laboratory study; cross-sectional. Background Little is known about ankle range of motion (ROM) and strength among patients with insertional Achilles tendinopathy (IAT) and whether limited ankle ROM and plantar flexor weakness impact IAT symptom severity. Objectives The purposes of the study were (1) to examine whether participants with IAT exhibit limited non-weight-bearing dorsiflexion ROM, reduced plantar flexor strength, and/or altered ankle biomechanics during stair ascent; and (2) to determine which impairments are associated with symptom severity. Methods Participants included 20 patients with unilateral IAT (mean ± SD age, 59 ± 8 years; 55% female) and 20 individuals without tendinopathy (age, 58.2 ± 8.5 years; 55% female). A dynamometer was used to measure non-weight-bearing ROM and isometric plantar flexor strength. Three-dimensional motion analysis was used to quantify ankle biomechanics during stair ascent. End-range dorsiflexion was quantified as the percentage of non-weight-bearing dorsiflexion used during stair ascent. Group differences were compared using 2-way and 1-way analyses of variance. Pearson correlations were used to test for associations among dependent variables and symptom severity. Results Groups differed in ankle biomechanics, but not non-weight-bearing ROM or strength. During stair ascent, the IAT group used greater end-range dorsiflexion (P = .03), less plantar flexion (P = .02), and lower peak ankle plantar flexor power (P = .01) than the control group. Higher end-range dorsiflexion and lower ankle power during stair ascent were associated with greater symptom severity (P<.05). Conclusion Patients with IAT do not experience restrictions in non-weight-bearing dorsiflexion ROM or isometric plantar flexor strength. However, altered ankle biomechanics during stair ascent were linked with greater symptom severity and likely contribute to decreased function. J Orthop Sports Phys Ther 2016;46(12):1051-1060. Epub 29 Oct 2016. doi:10.2519/jospt.2016.6462.

PMMA-augmented SI screw: a biomechanical analysis of stiffness and pull-out force in a matched paired human cadaveric model.

PubMed

Grechenig, Stephan; Gänsslen, Axel; Gueorguiev, Boyko; Berner, Arne; Müller, Michael; Nerlich, Michael; Schmitz, Paul

2015-10-01

Current literature data and clinical experience show that the number of pelvic fractures continuously rises due to the increasing elderly population. In the elderly with suspected osteoporosis additional implant augmentation with bone cement seems to be an option to avoid secondary displacement. There are no reported biomechanical data in the literature comparing the fixation strength (and anchorage) of standard and augmented SI screws so far. The purpose of this study was to assess the biomechanical performance of cement-augmented versus non-augmented SI screws in a human cadaveric pelvis model. Six human cadaveric pelvises preserved with the method of Thiel were used in this study. Each pelvis was split to a pair of 2 hemi-pelvises, assigned to 2 different groups for instrumentation with one non-augmented or one contralateral cement-augmented SI screw, placed in the body of S1 in a randomized fashion. The osteosynthesis followed a standard procedure with 3D controlled percutaneous iliosacral screw positioning. A biomechanical setup for a quasistatic pullout test of each SI screw was used. Construct stiffness and maximum pullout force were calculated from the load-displacement curve of the machine data. Statistical evaluation was performed at a level of significance p = .05 for all statistical tests. Stiffness and pullout force in the augmented group (501.6 N/mm ± 123.7, 1336.8 N ± 221.1) were significantly higher than in the non-augmented one (289.7 N/mm ± 97.1, 597.7 N ± 115.5), p = .04 and p = .014, respectively. BMD influenced significantly the pullout force in all study groups. Cement augmentation significantly increased the fixation strength in iliosacral screw osteosynthesis of the sacrum in a biomechanical human cadaveric model. Copyright © 2015 Elsevier Ltd. All rights reserved.

Biomechanical characteristics of fixation methods for floating pubic symphysis.

PubMed

Song, Wenhao; Zhou, Dongsheng; He, Yu

2017-03-07

Floating pubic symphysis (FPS) is a relatively rare injury caused by high-energy mechanisms. There are several fixation methods used to treat FPS, including external fixation, subcutaneous fixation, internal fixation, and percutaneous cannulated screw fixation. To choose the appropriate fixation, it is necessary to study the biomechanical performance of these different methods. The goal of this study was to compare the biomechanical characteristics of six methods by finite element analysis. A three-dimensional finite element model of FPS was simulated. Six methods were used in the FPS model, including external fixation (Ext), subcutaneous rod fixation (Sub-rod), subcutaneous plate fixation (Sub-plate), superior pectineal plate fixation (Int-sup), infrapectineal plate fixation (Int-ifa), and cannulated screw fixation (Int-scr). Compressive and rotational loads were then applied in all models. Biomechanical characteristics that were recorded and analyzed included construct stiffness, micromotion of the fracture gaps, von Mises stress, and stress distribution. The construct stiffness of the anterior pelvic ring was decreased dramatically when FPS occurred. Compressive stiffness was restored by the three internal fixation and Sub-rod methods. Unfortunately, rotational stiffness was not restored satisfactorily by the six methods. For micromotion of the fracture gaps, the displacement was reduced significantly by the Int-sup and Int-ifa methods under compression. The internal fixation methods and Sub-plate method performed well under rotation. The maximum von Mises stress of the implants was not large. For the plate-screw system, the maximum von Mises stress occurred over the region of the fracture and plate-screw joints. The maximum von Mises stress appeared on the rod-screw and screw-bone interfaces for the rod-screw system. The present study showed the biomechanical advantages of internal fixation methods for FPS from a finite element view. Superior stabilization of the anterior pelvic ring and fracture gaps was obtained by internal fixation. Subcutaneous fixation had satisfactory outcomes as well. Sub-rod fixation offered good anti-compression, while the Sub-plate fixation provided favorable anti-rotational capacity.

MR Morphology of Triangular Fibrocartilage Complex: Correlation with Quantitative MR and Biomechanical Properties

PubMed Central

Bae, Won C.; Ruangchaijatuporn, Thumanoon; Chang, Eric Y; Biswas, Reni; Du, Jiang; Statum, Sheronda

2016-01-01

Objective To evaluate pathology of the triangular fibrocartilage complex (TFCC) using high resolution morphologic magnetic resonance (MR) imaging, and compare with quantitative MR and biomechanical properties. Materials and Methods Five cadaveric wrists (22 to 70 yrs) were imaged at 3T using morphologic (proton density weighted spin echo, PD FS, and 3D spoiled gradient echo, 3D SPGR) and quantitative MR sequences to determine T2 and T1rho properties. In eight geographic regions, morphology of TFC disc and laminae were evaluated for pathology and quantitative MR values. Samples were disarticulated and biomechanical indentation testing was performed on the distal surface of the TFC disc. Results On morphologic PD SE images, TFC disc pathology included degeneration and tears, while that of the laminae included degeneration, degeneration with superimposed tear, mucinous transformation, and globular calcification. Punctate calcifications were highly visible on 3D SPGR images and found only in pathologic regions. Disc pathology occurred more frequently in proximal regions of the disc than distal regions. Quantitative MR values were lowest in normal samples, and generally higher in pathologic regions. Biomechanical testing demonstrated an inverse relationship, with indentation modulus being high in normal regions with low MR values. The laminae studied were mostly pathologic, and additional normal samples are needed to discern quantitative changes. Conclusion These results show technical feasibility of morphologic MR, quantitative MR, and biomechanical techniques to characterize pathology of the TFCC. Quantitative MRI may be a suitable surrogate marker of soft tissue mechanical properties, and a useful adjunct to conventional morphologic MR techniques. PMID:26691643

Alcoholism and traumatic subarachnoid hemorrhage: an experimental study on vascular morphology and biomechanics.

PubMed

Wang, Haipeng; Yu, Xiaojun; Xu, Guohui; Xu, Guangtao; Gao, Guishan; Xu, Xiaohu

2011-01-01

Traumatic subarachnoid hemorrhage (TSAH) related to alcohol abuse is a notable risk factor. Here, we investigated the vascular morphology and biomechanics of TSAH in rat models of acute alcoholic intoxication and chronic alcoholism rats to explore the possible mechanisms of TSAH. Sixty male Sprague-Dawley rats were divided into acute alcoholic intoxication and chronic alcoholism groups. Edible spirituous liquor (56% vol/vol) was intragastrically given (15 mL/kg) once to the rats in the acute group, and given twice daily (8 mL/kg for 2 weeks and 12 mL/kg for another 2 weeks) to rats in the chronic group. A self-made instrument was used to inflict head injury. Whole brain, arterial blood, and thoracic aorta of rats were sampled for morphologic and biomechanical examination. Compared with the acute alcoholic rats, the chronic alcoholic rats showed significant morphologic and biomechanical changes: (1) decreased body weight (p<0.05), (2) higher morbidity and mortality from TSAH (p<0.01), (3) greater mean thickness of vascular wall of subarachnoid small arteries and each layer thickness of thoracic aorta (p<0.05), (4) decreased failure load and corresponding extensibility (60 kPa and limit load) of thoracic aorta, and (5) increased elastic modulus (30 kPa, range in physiologic stress) (p<0.05). Chronic alcoholism can induce the morphologic and biomechanical changes in cerebral vessels and thoracic aorta. The synergistic effect of alcohol abuse and minor blow may be one of the mechanisms of TSAH. High blood pressure from long-term alcohol abuse is also a notable factor.

A novel mouse running wheel that senses individual limb forces: biomechanical validation and in vivo testing

PubMed Central

Roach, Grahm C.; Edke, Mangesh

2012-01-01

Biomechanical data provide fundamental information about changes in musculoskeletal function during development, adaptation, and disease. To facilitate the study of mouse locomotor biomechanics, we modified a standard mouse running wheel to include a force-sensitive rung capable of measuring the normal and tangential forces applied by individual paws. Force data were collected throughout the night using an automated threshold trigger algorithm that synchronized force data with wheel-angle data and a high-speed infrared video file. During the first night of wheel running, mice reached consistent running speeds within the first 40 force events, indicating a rapid habituation to wheel running, given that mice generated >2,000 force-event files/night. Average running speeds and peak normal and tangential forces were consistent throughout the first four nights of running, indicating that one night of running is sufficient to characterize the locomotor biomechanics of healthy mice. Twelve weeks of wheel running significantly increased spontaneous wheel-running speeds (16 vs. 37 m/min), lowered duty factors (ratio of foot-ground contact time to stride time; 0.71 vs. 0.58), and raised hindlimb peak normal forces (93 vs. 115% body wt) compared with inexperienced mice. Peak normal hindlimb-force magnitudes were the primary force component, which were nearly tenfold greater than peak tangential forces. Peak normal hindlimb forces exceed the vertical forces generated during overground running (50-60% body wt), suggesting that wheel running shifts weight support toward the hindlimbs. This force-instrumented running-wheel system provides a comprehensive, noninvasive screening method for monitoring gait biomechanics in mice during spontaneous locomotion. PMID:22723628

Structural and biomechanical characteristics after early mobilization in an Achilles tendon rupture model: operative versus nonoperative treatment.

PubMed

Krapf, Daniel; Kaipel, Martin; Majewski, Martin

2012-09-01

Acute Achilles tendon ruptures are common sports injuries; however, treatment remains a clinical challenge. Studies show a superior effect of early mobilization and full weight bearing on tendon healing and clinical outcome; however, few data exist on structural and biomechanical characteristics in the early healing phase. This study investigated the histological and biomechanical characteristics of early mobilization and full weight bearing in an Achilles tendon rupture model. Eighty rats underwent dissection of a hindpaw Achilles tendon; 40 rats were treated conservatively and 40 underwent open repair of the transected Achilles tendon by suturing. Early mobilization and full weight bearing were allowed in both groups. At 1, 2, 4, and 8 weeks after tenotomy, tensile strength, stiffness, thickness, tissue characteristics (histological analysis), and length were determined. Dissected Achilles tendons healed in all animals during full weight-bearing early mobilization. One and 2 weeks after tenotomy, rats in the operative group showed increased tensile strength and stiffness compared with the nonoperative group. Repair-site diameters were increased at 1, 2, and 8 weeks after tenotomy. Tendon length was decreased in the operative group throughout observation, whereas the nonoperative group showed increased structural characteristics on the cellular level and a more homogeneous collagen distribution. Surgical treatment of dissected rat Achilles tendons showed superior biomechanical characteristics within the first 2 weeks. Conservative treatment resulted in superior histological findings but significant lengthening of the tendon in the early healing phase (weeks 1-8). Copyright 2012, SLACK Incorporated.

Multibody system of the upper limb including a reverse shoulder prosthesis.

PubMed

Quental, C; Folgado, J; Ambrósio, J; Monteiro, J

2013-11-01

The reverse shoulder replacement, recommended for the treatment of several shoulder pathologies such as cuff tear arthropathy and fractures in elderly people, changes the biomechanics of the shoulder when compared to the normal anatomy. Although several musculoskeletal models of the upper limb have been presented to study the shoulder joint, only a few of them focus on the biomechanics of the reverse shoulder. This work presents a biomechanical model of the upper limb, including a reverse shoulder prosthesis, to evaluate the impact of the variation of the joint geometry and position on the biomechanical function of the shoulder. The biomechanical model of the reverse shoulder is based on a musculoskeletal model of the upper limb, which is modified to account for the properties of the DELTA® reverse prosthesis. Considering two biomechanical models, which simulate the anatomical and reverse shoulder joints, the changes in muscle lengths, muscle moment arms, and muscle and joint reaction forces are evaluated. The muscle force sharing problem is solved for motions of unloaded abduction in the coronal plane and unloaded anterior flexion in the sagittal plane, acquired using video-imaging, through the minimization of an objective function related to muscle metabolic energy consumption. After the replacement of the shoulder joint, significant changes in the length of the pectoralis major, latissimus dorsi, deltoid, teres major, teres minor, coracobrachialis, and biceps brachii muscles are observed for a reference position considered for the upper limb. The shortening of the teres major and teres minor is the most critical since they become unable to produce active force in this position. Substantial changes of muscle moment arms are also observed, which are consistent with the literature. As expected, there is a significant increase of the deltoid moment arms and more fibers are able to elevate the arm. The solutions to the muscle force sharing problem support the biomechanical advantages attributed to the reverse shoulder design and show an increase in activity from the deltoid, teres minor, and coracobrachialis muscles. The glenohumeral joint reaction forces estimated for the reverse shoulder are up to 15% lower than those in the normal shoulder anatomy. The data presented here complements previous publications, which, all together, allow researchers to build a biomechanical model of the upper limb including a reverse shoulder prosthesis.

Trunk biomechanics during hemiplegic gait after stroke: A systematic review.

PubMed

Van Criekinge, Tamaya; Saeys, Wim; Hallemans, Ann; Velghe, Silke; Viskens, Pieter-Jan; Vereeck, Luc; De Hertogh, Willem; Truijen, Steven

2017-05-01

Stroke commonly results in trunk impairments that are associated with decreased trunk coordination and limited trunk muscle strength. These impairments often result in biomechanical changes during walking. Additionally, the so-called pelvic step might be influenced by these impairments. Therefore, the aim of this review was twofold. First, to gain more insight into trunk biomechanics during walking in stroke patients compared to healthy individuals. Second, to investigate the influence of walking speed on trunk biomechanics. The search strategy was performed by the PRISMA guidelines and registered in the PROSPERO database (no. CRD42016035797). Databases MEDLINE, Web of Science, Cochrane Library, ScienceDirect, and Rehabdata were systematically searched until December 2016. Sixteen of the 1099 studies met the eligibility criteria and were included in this review. Risk of bias was assessed by the Newcastle-Ottawa Scale. The majority of studies reported on trunk kinematics during walking, data on trunk kinetics and muscle activity is lacking. Following stroke, patients walk with increased mediolateral trunk sway and larger sagittal motion of the lower trunk. Although rotation of the upper trunk is increased, the trunk shows a more in-phase coordination. Acceleration of the trunk diminishes while instability and asymmetry increase as there are less movement towards the paretic side. However, it is of great importance to differentiate between compensatory trunk movements and intrinsic trunk control deficits. Specific exercise programs, assistive devices and orthoses might be of help in controlling these deficits. Importantly, studies suggested that more natural trunk movements were observed when walking speed was increased. Copyright © 2017 Elsevier B.V. All rights reserved.

Biomechanical Properties of The Vaginal Wall: Effect of Pregnancy, Elastic Fiber Deficiency, and Pelvic Organ Prolapse

PubMed Central

Rahn, David D.; Ruff, Matthew D.; Brown, Spencer A.; Tibbals, Harry F.; Word, R. Ann

2009-01-01

Objectives To identify pregnancy-induced changes in biomechanical properties of the vaginal wall and compare these with Fibulin-5 knockout mice (Fbln5-/-) with and without prolapse. Study Design Mid-vaginal segments of nonpregnant and late-pregnant wild type (WT), Fbln5-/- with prolapse, and Fbln5-/- mice without prolapse were studied. Tissue length at failure, maximal strain, maximal stress, and tissue stiffness were determined. Results Compared with nonpregnant mice, vaginas of pregnant and Fbln5-/- (with prolapse) mice exhibited decreased maximal stress, increased distensibility and strain, and decreased stiffness. Tissues from Fbln5-/- mice without prolapse were similar to nonpregnant WT animals. Conclusions Pregnancy confers remarkable changes in the vaginal wall including increased distensibility and decreased stiffness and maximal stress. Elastinopathy alone is insufficient to cause significant changes in these properties, but prolapse confers additional alterations in distensibility and stiffness similar to those observed in pregnancy. These changes may contribute to the poor durability of many restorative surgical procedures for prolapse. PMID:18455541

Comparison between overground and dynamometer manual wheelchair propulsion.

PubMed

Koontz, Alicia M; Worobey, Lynn A; Rice, Ian M; Collinger, Jennifer L; Boninger, Michael L

2012-08-01

Laboratory-based simulators afford many advantages for studying physiology and biomechanics; however, they may not perfectly mimic wheelchair propulsion over natural surfaces. The goal of this study was to compare kinetic and temporal parameters between propulsion overground on a tile surface and on a dynamometer. Twenty-four experienced manual wheelchair users propelled at a self-selected speed on smooth, level tile and a dynamometer while kinetic data were collected using an instrumented wheel. A Pearson correlation test was used to examine the relationship between propulsion variables obtained on the dynamometer and the overground condition. Ensemble resultant force and moment curves were compared using cross-correlation and qualitative analysis of curve shape. User biomechanics were correlated (R ranging from 0.41 to 0.83) between surfaces. Overall, findings suggest that although the dynamometer does not perfectly emulate overground propulsion, wheelchair users were consistent with the direction and amount of force applied, the time peak force was reached, push angle, and their stroke frequency between conditions.

Comparison Between Overground and Dynamometer Manual Wheelchair Propulsion

PubMed Central

Worobey, Lynn A.; Rice, Ian M.; Collinger, Jennifer L.; Boninger, Michael L.

2017-01-01

Laboratory-based simulators afford many advantages for studying physiology and biomechanics; however, they may not perfectly mimic wheelchair propulsion over natural surfaces. The goal of this study was to compare kinetic and temporal parameters between propulsion overground on a tile surface and on a dynamometer. Twenty-four experienced manual wheelchair users propelled at a self-selected speed on smooth, level tile and a dynamometer while kinetic data were collected using an instrumented wheel. A Pearson correlation test was used to examine the relationship between propulsion variables obtained on the dynamometer and the overground condition. Ensemble resultant force and moment curves were compared using cross-correlation and qualitative analysis of curve shape. User biomechanics were correlated (R ranging from 0.41 to 0.83) between surfaces. Overall, findings suggest that although the dynamometer does not perfectly emulate overground propulsion, wheelchair users were consistent with the direction and amount of force applied, the time peak force was reached, push angle, and their stroke frequency between conditions. PMID:22085811

The use of McConnell taping to correct abnormal biomechanics and muscle activation patterns in subjects with anterior knee pain: a systematic review

PubMed Central

Leibbrandt, Dominique C; Louw, Quinette A

2015-01-01

[Purpose] The aim of this review was to present the available evidence for the effect of McConnell taping on knee biomechanics in individuals with anterior knee pain. [Methods] The PubMed, Medline, Cinahl, SPORTDiscus, PEDro and ScienceDirect electronic databases were searched from inception until September 2014. Experimental research on knee biomechanical or EMG outcomes of McConnell taping compared with no tape or placebo tape were included. Two reviewers completed the searches, selected the full text articles, and assessed the risk of bias of eligible studies. Authors were contacted for missing data. [Results] Eight heterogeneous studies with a total sample of 220 were included in this review. All of the studies had a moderate to low risk of bias. Pooling of data was possible for three outcomes: average knee extensor moment, average VMO/VL ratio and average VMO-VL onset timing. None of these outcomes revealed significant differences. [Conclusion] The evidence is currently insufficient to justify routine use of the McConnell taping technique in the treatment of anterior knee pain. There is a need for more evidence on the aetiological pathways of anterior knee pain, level one evidence, and studies investigating other potential mechanisms of McConnell taping. PMID:26311990

Ankle and knee biomechanics during normal walking following ankle plantarflexor fatigue.

PubMed

Hunt, Michael A; Hatfield, Gillian L

2017-08-01

The purpose of this study was to investigate the immediate effects of unilateral ankle plantarflexor fatigue on bilateral knee and ankle biomechanics during gait. Lower leg kinematics, kinetics, and muscle activation were assessed before and after an ankle plantarflexor fatiguing protocol in 31 healthy individuals. Fatigue (defined as >10% reduction in maximal isometric ankle plantarflexor torque production and a downward shift in the median power frequency of both heads of the gastrocnemius muscle of the fatigued limb) was achieved in 18 individuals, and only their data were used for analysis purposes. Compared to pre-fatigue walking trials, medial gastrocnemius activity was significantly reduced in the study (fatigued) limb. Other main changes following fatigue included significantly more knee flexion during loading, and an associated larger external knee flexion moment in the study limb. At the ankle joint, participants exhibited significantly less peak plantarflexion (occurring at toe-off) with fatigue. No significant differences were observed in the contralateral (non-fatigued) limb. Findings from this study indicate that fatigue of the ankle plantarflexor muscle does not produce widespread changes in gait biomechanics, suggesting that small to moderate changes in maximal ankle plantarflexor force production capacity (either an increase or decrease) will not have a substantial impact on normal lower limb functioning during gait. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biomechanics principle of elbow joint for transhumeral prostheses: comparison of normal hand, body-powered, myoelectric & air splint prostheses.

PubMed

Abd Razak, Nasrul Anuar; Abu Osman, Noor Azuan; Gholizadeh, Hossein; Ali, Sadeeq

2014-09-10

Understanding of kinematics force applied at the elbow is important in many fields, including biomechanics, biomedical engineering and rehabilitation. This paper provides a comparison of a mathematical model of elbow joint using three different types of prosthetics for transhumeral user, and characterizes the forces required to overcome the passive mechanical of the prosthetics at the residual limb. The study modeled the elbow as a universal joint with intersecting axes of x-axis and y-axis in a plain of upper arm and lower arm. The equations of force applied, torque, weight and length of different type of prosthetics and the anthropometry of prosthetics hand are discussed in this study. The study also compares the force, torque and pressure while using all three types of prosthetics with the normal hand. The result was measured from the elbow kinematics of seven amputees, using three different types of prosthetics. The F-Scan sensor used in the study is to determine the pressure applied at the residual limb while wearing different type of prostheses. These technological advances in assessment the biomechanics of an elbow joint for three different type of prosthetics with the normal hand bring the new information for the amputees and prosthetist to choose the most suitable device to be worn daily.

Effects of an age-specific anterior cruciate ligament injury prevention program on lower extremity biomechanics in children.

PubMed

DiStefano, Lindsay J; Blackburn, J Troy; Marshall, Stephen W; Guskiewicz, Kevin M; Garrett, William E; Padua, Darin A

2011-05-01

Implementing an anterior cruciate ligament injury prevention program to athletes before the age at which the greatest injury risk occurs (15-17 years) is important from a prevention standpoint. However, it is unknown whether standard programs can modify lower extremity biomechanics in pediatric populations or if specialized training is required. To compare the effects of traditional and age-specific pediatric anterior cruciate ligament injury prevention programs on lower extremity biomechanics during a cutting task in youth athletes. The authors hypothesized that the age-specific pediatric program would result in greater sagittal plane motion (ie, hip and knee flexion) and less motion in the transverse and frontal plane (ie, knee valgus, knee and hip rotation) as compared with the traditional program. Randomized controlled trial; Level of evidence, 1. Sixty-five youth soccer athletes (38 boys, 27 girls) volunteered to participate. The mean age of participants was 10 ± 1 years. Teams (n, 7) were cluster randomized to a pediatric injury prevention program, a traditional injury prevention program, or a control group. The pediatric program was modified from the traditional program to include more feedback, progressions, and variety. Teams performed their programs as part of their normal warm-up routine. Three-dimensional lower extremity biomechanics were assessed during a sidestep cutting task before and after completion of the 9-week intervention period. The pediatric program reduced the amount of knee external rotation at initial ground contact during the cutting task, F ((2,62)) = 3.79, P = .03 (change: pediatric, 7.73° ± 10.71°; control, -0.35° ± 7.76°), as compared with the control group after the intervention period. No other changes were observed. The injury prevention program designed for a pediatric population modified only knee rotation during the cutting task, whereas the traditional program did not result in any changes in cutting biomechanics. These findings suggest limited effectiveness of both programs for athletes younger than 12 years of age in terms of biomechanics during a cutting task.

The Evolutionary Fate of Phenotypic Plasticity and Functional Traits under Domestication in Manioc: Changes in Stem Biomechanics and the Appearance of Stem Brittleness

PubMed Central

Ménard, Léa; McKey, Doyle; Mühlen, Gilda S.; Clair, Bruno; Rowe, Nick P.

2013-01-01

Domestication can influence many functional traits in plants, from overall life-history and growth form to wood density and cell wall ultrastructure. Such changes can increase fitness of the domesticate in agricultural environments but may negatively affect survival in the wild. We studied effects of domestication on stem biomechanics in manioc by comparing domesticated and ancestral wild taxa from two different regions of greater Amazonia. We compared mechanical properties, tissue organisation and wood characteristics including microfibril angles in both wild and domesticated plants, each growing in two different habitats (forest or savannah) and varying in growth form (shrub or liana). Wild taxa grew as shrubs in open savannah but as lianas in overgrown and forested habitats. Growth form plasticity was retained in domesticated manioc. However, stems of the domesticate showed brittle failure. Wild plants differed in mechanical architecture between shrub and liana phenotypes, a difference that diminished between shrubs and lianas of the domesticate. Stems of wild plants were generally stiffer, failed at higher bending stresses and were less prone to brittle fracture compared with shrub and liana phenotypes of the domesticate. Biomechanical differences between stems of wild and domesticated plants were mainly due to changes in wood density and cellulose microfibril angle rather than changes in secondary growth or tissue geometry. Domestication did not significantly modify “large-scale” trait development or growth form plasticity, since both wild and domesticated manioc can develop as shrubs or lianas. However, “finer-scale” developmental traits crucial to mechanical stability and thus ecological success of the plant were significantly modified. This profoundly influenced the likelihood of brittle failure, particularly in long climbing stems, thereby also influencing the survival of the domesticate in natural situations vulnerable to mechanical perturbation. We discuss the different selective pressures that could explain evolutionary modifications of stem biomechanical properties under domestication in manioc. PMID:24023960

Biomechanical Analysis of an Expandable Lumbar Interbody Spacer.

PubMed

Soriano-Baron, Hector; Newcomb, Anna G U S; Malhotra, Devika; Palma, Atilio E; Martinez-Del-Campo, Eduardo; Crawford, Neil R; Theodore, Nicholas; Kelly, Brian P; Kaibara, Taro

2018-06-01

Recently developed expandable interbody spacers are widely accepted in spinal surgery; however, the resulting biomechanical effects of their use have not yet been fully studied. We analyzed the biomechanical effects of an expandable polyetheretherketone interbody spacer inserted through a bilateral posterior approach with and without different modalities of posterior augmentation. Biomechanical nondestructive flexibility testing was performed in 7 human cadaveric lumbar (L2-L5) specimens followed by axial compressive loading. Each specimen was tested under 6 conditions: 1) intact, 2) bilateral L3-L4 cortical screw/rod (CSR) alone, 3) WaveD alone, 4) WaveD + CSR, 5) WaveD + bilateral L3-L4 pedicle screw/rod (PSR), and 6) WaveD + CSR/PSR, where CSR/PSR was a hybrid construct comprising bilateral cortical-level L3 and pedicle-level L4 screws interconnected by rods. The range of motion (ROM) with the interbody spacer alone decreased significantly compared with the intact condition during flexion-extension (P = 0.02) but not during lateral bending or axial rotation (P ≥ 0.19). The addition of CSR or PSR to the interbody spacer alone condition significantly decreased the ROM compared with the interbody spacer alone (P ≤ 0.002); and WaveD + CSR, WaveD + PSR, and WaveD + CSR/PSR (hybrid) (P ≥ 0.29) did not differ. The axial compressive stiffness (resistance to change in foraminal height during compressive loading) with the interbody spacer alone did not differ from the intact condition (P = 0.96), whereas WaveD + posterior instrumentation significantly increased compressive stiffness compared with the intact condition and the interbody spacer alone (P ≤ 0.001). The WaveD alone significantly reduced ROM during flexion-extension while maintaining the axial compressive stiffness. CSR, PSR, and CSR/PSR hybrid constructs were all effective in augmenting the expandable interbody spacer system and improving its stability. Copyright © 2018 Elsevier Inc. All rights reserved.

Biomechanical characterization of double-bundle femoral press-fit fixation techniques.

PubMed

Ettinger, M; Haasper, C; Hankemeier, S; Hurschler, C; Breitmeier, D; Krettek, C; Jagodzinski, M

2011-03-01

Press-fit fixation of patellar tendon bone anterior cruciate ligament autografts is an interesting technique because no hardware is necessary. To date, no biomechanical data exist describing an implant-free double-bundle press-fit procedure. The purpose of this study was to characterize the biomechanical properties of three double-bundle press-fit fixations. In a controlled laboratory study, the patellar-, quadriceps- and hamstring tendons of 10 human cadavers (age: 49.2 ± 18.5 years) were used. An inside out press-fit fixation with a knot in the semitendinosus and gracilis tendons (SG) combined with an additional bone block, with two quadriceps tendon bone block grafts (QU) was compared with press-fit fixation of two bone patellar tendon bone block (PT) grafts in 30 porcine femora. Constructs were cyclically stretched and then loaded until failure. Maximum load to failure, stiffness and elongation during failure testing and cyclical loading were investigated. The maximum load to failure was 703 ± 136 N for SG fixation, 632 ± 130 N for QU and 656 ± 127 N for PT fixation. Stiffness of the constructs averaged 138 ± 26 N/mm for SG, 159 ± 74 N/mm for QU, and 154 ± 50 N/mm for PT fixation. Elongation during initial cyclical loading was 1.2 ± 1.4 mm for SG, 2.0 ± 1.4 mm for QU, and 1.0 ± 0.6 mm for PT (significantly larger for PT and QU between the first 5 cycles compared with cycles 15-20th, P < 0.01). All investigated double-bundle fixation techniques were equal in terms of maximum load to failure, stiffness, and elongation. Unlike with single-bundle press-fit fixation techniques that have been published, no difference was observed between pure tendon combined with an additional bone block and tendon bone grafts. All techniques exhibited larger elongation during initial cyclical loading. All three press-fit fixation techniques that were investigated exhibit comparable biomechanical properties. Preconditioning of the constructs is critical.

Treatment of Ulnar Collateral Ligament Tears of the Elbow: Is Repair a Viable Option?

PubMed

Erickson, Brandon J; Bach, Bernard R; Verma, Nikhil N; Bush-Joseph, Charles A; Romeo, Anthony A

2017-01-01

Ulnar collateral ligament (UCL) tears have become common, and UCL reconstruction (UCLR) is currently the preferred surgical treatment method for treating UCL tears. The purpose of this study was to review the literature surrounding UCL repair and determine the viability of new repair techniques for treatment of UCL tears. We hypothesized that UCL repair techniques will provide comparable results to UCLR for treatment of UCL tears. Systematic review and meta-analysis; Level of evidence, 4. A systematic review was registered with PROSPERO and performed with PRISMA guidelines using 3 publicly available free databases. Biomechanical and clinical outcome investigations reporting on UCL repair with levels of evidence 1 through 4 were eligible for inclusion. Descriptive statistics were calculated for each study and parameter/variable analyzed. Of the 46 studies eligible, 4 studies (3 clinical and 1 biomechanical) were included. There were 92 patients (n = 92 elbows; 61 males [62.3%]; mean age, 21.9 ± 4.7 years) included in the clinical studies, with a mean follow-up of 49 ± 14.4 months. Eighty-six percent of repairs performed were on the dominant elbow, and 38% were in college athletes. Most UCL repairs (66.3%) were performed via suture anchors. After UCL repair, 87.0% of patients were able to return to sport. Overall, 94.9% of patients scored excellent/good on the Andrews-Carson score. Patients who were able to return to sport after UCL repair did so within 6 months after surgery. Biomechanically, when UCL repair was compared with the modified Jobe technique, the repair group showed significantly less gap formation than the reconstruction group. In patients for whom repair is properly indicated, UCL repair provides similar return-to-sport rates and clinical outcomes with shorter return-to-sport timing after repair compared with UCL reconstruction. Future outcome studies evaluating UCL repair with internal bracing are necessary before recommending this technique.

Biomechanical compensations of the trunk and lower extremities during stepping tasks after unilateral transtibial amputation.

PubMed

Murray, Amanda M; Gaffney, Brecca M; Davidson, Bradley S; Christiansen, Cory L

2017-11-01

Lower extremity movement compensations following transtibial amputation are well-documented and are likely influenced by trunk posture and movement. However, the biomechanical compensations of the trunk and lower extremities, especially during high-demand tasks such as step ascent and descent, remain unclear. Kinematic and kinetic data were collected during step ascent and descent tasks for three groups of individuals: diabetic/transtibial amputation, diabetic, and healthy. An ANCOVA was used to compare peak trunk, hip and knee joint angles and moments in the sagittal and frontal planes between groups. Paired t-tests were used to compare peak joint angles and moments between amputated and intact limbs of the diabetic/transtibial amputation group. During step ascent and descent, the transtibial amputation group exhibited greater trunk forward flexion and lateral flexion compared to the other two groups (P<0.016), which resulted in greater low back moments and asymmetric loading patterns in the lower extremity joints. The diabetic group exhibited similar knee joint loading patterns compared to the amputation group (P<0.016), during step descent. This study highlights the biomechanical compensations of the trunk and lower extremities in individuals with dysvascular transtibial amputation, by identifying low back, hip, and knee joint moment patterns unique to transtibial amputation during stepping tasks. In addition, the results suggest that some movement compensations may be confounded by the presence of diabetes and precede limb amputation. The increased and asymmetrical loading patterns identified may predispose individuals with transtibial amputation to the development of secondary pain conditions, such as low back pain or osteoarthritis. Copyright © 2017 Elsevier Ltd. All rights reserved.

In vivo biomechanical evaluation of a novel angle-stable interlocking nail design in a canine tibial fracture model.

PubMed

Déjardin, Loïc M; Cabassu, Julien B; Guillou, Reunan P; Villwock, Mark; Guiot, Laurent P; Haut, Roger C

2014-03-01

To compare clinical outcome and callus biomechanical properties of a novel angle stable interlocking nail (AS-ILN) and a 6 mm bolted standard ILN (ILN6b) in a canine tibial fracture model. Experimental in vivo study. Purpose-bred hounds (n = 11). A 5 mm mid-diaphyseal tibial ostectomy was stabilized with an AS-ILN (n = 6) or an ILN6b (n = 5). Orthopedic examinations and radiographs were performed every other week until clinical union (18 weeks). Paired tibiae were tested in torsion until failure. Callus torsional strength and toughness were statistically compared and failure mode described. Total and cortical callus volumes were computed and statistically compared from CT slices of the original ostectomy gap. Statistical significance was set at P < .05 RESULTS: From 4 to 8 weeks, lameness was less pronounced in AS-ILN than ILN6b dogs (P < .05). Clinical union was reached in all AS-ILN dogs by 10 weeks and in 3/5 ILN6b dogs at 18 weeks. Callus mechanical properties were significantly greater in AS-ILN than ILN6b specimens by 77% (failure torque) and 166% (toughness). Failure occurred by acute spiral (control and AS-ILN) or progressive transverse fractures (ILN6b). Cortical callus volume was 111% greater in AS-ILN than ILN6b specimens (P < .05). Earlier functional recovery, callus strength and remodeling suggest that the AS-ILN provides a postoperative biomechanical environment more conducive to bone healing than a comparable standard ILN. © Copyright 2014 by The American College of Veterinary Surgeons.

Developmental dysplasia of the hip: A computational biomechanical model of the path of least energy for closed reduction.

PubMed

Zwawi, Mohammed A; Moslehy, Faissal A; Rose, Christopher; Huayamave, Victor; Kassab, Alain J; Divo, Eduardo; Jones, Brendan J; Price, Charles T

2017-08-01

This study utilized a computational biomechanical model and applied the least energy path principle to investigate two pathways for closed reduction of high grade infantile hip dislocation. The principle of least energy when applied to moving the femoral head from an initial to a final position considers all possible paths that connect them and identifies the path of least resistance. Clinical reports of severe hip dysplasia have concluded that reduction of the femoral head into the acetabulum may occur by a direct pathway over the posterior rim of the acetabulum when using the Pavlik harness, or by an indirect pathway with reduction through the acetabular notch when using the modified Hoffman-Daimler method. This computational study also compared the energy requirements for both pathways. The anatomical and muscular aspects of the model were derived using a combination of MRI and OpenSim data. Results of this study indicate that the path of least energy closely approximates the indirect pathway of the modified Hoffman-Daimler method. The direct pathway over the posterior rim of the acetabulum required more energy for reduction. This biomechanical analysis confirms the clinical observations of the two pathways for closed reduction of severe hip dysplasia. The path of least energy closely approximated the modified Hoffman-Daimler method. Further study of the modified Hoffman-Daimler method for reduction of severe hip dysplasia may be warranted based on this computational biomechanical analysis. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 35:1799-1805, 2017. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society.

Energetics, Biomechanics, and Performance in Masters' Swimmers: A Systematic Review.

PubMed

Ferreira, Maria I; Barbosa, Tiago M; Costa, Mário J; Neiva, Henrique P; Marinho, Daniel A

2016-07-01

Ferreira, MI, Barbosa, TM, Costa, MJ, Neiva, HP, and Marinho, DA. Energetics, biomechanics, and performance in masters' swimmers: a systematic review. J Strength Cond Res 30(7): 2069-2081, 2016-This study aimed to summarize evidence on masters' swimmers energetics, biomechanics, and performance gathered in selected studies. An expanded search was conducted on 6 databases, conference proceedings, and department files. Fifteen studies were selected for further analysis. A qualitative evaluation of the studies based on the Quality Index (QI) was performed by 2 independent reviewers. The studies were thereafter classified into 3 domains according to the reported data: performance (10 studies), energetics (4 studies), and biomechanics (6 studies). The selected 15 articles included in this review presented low QI scores (mean score, 10.47 points). The biomechanics domain obtained higher QI (11.5 points), followed by energetics and performance (10.6 and 9.9 points, respectively). Stroke frequency (SF) and stroke length (SL) were both influenced by aging, although SF is more affected than SL. Propelling efficiency (ηp) decreased with age. Swimming performance declined with age. The performance declines with age having male swimmers deliver better performances than female counterparts, although this difference tends to be narrow in long-distance events. One single longitudinal study is found in the literature reporting the changes in performance over time. The remaining studies are cross-sectional designs focusing on the energetics and biomechanics. Overall, biomechanics parameters, such as SF, SL, and ηp, tend to decrease with age. This review shows the lack of a solid body of knowledge (reflected in the amount and quality of the articles published) on the changes in biomechanics, energetics, and performance of master swimmers over time. The training programs for this age-group should aim to preserve the energetics as much as possible and, concurrently, improve the technique. Training sessions should feature a higher percentage of technical drills with the goal of enhancing the swim technique. Another goal should be the association of technique enhancement with aerobic and anaerobic sets, enabling the swimmer to improve the swimming efficiency.

Establishing Corneal Cross-Linking With Riboflavin and UV-A in the Mouse Cornea In Vivo: Biomechanical Analysis.

PubMed

Hammer, Arthur; Kling, Sabine; Boldi, Marc-Olivier; Richoz, Olivier; Tabibian, David; Randleman, J Bradley; Hafezi, Farhad

2015-10-01

To establish corneal cross-linking (CXL) with riboflavin and UV-A in in the mouse cornea in vivo and to develop tools to measure the biomechanical changes observed. A total of 55 male C57BL/6 wild-type mice (aged 5 weeks) were divided into 14 groups. Standard CXL parameters were adapted to the anatomy of the mouse cornea, and riboflavin concentration (0.1%-0.5%) and fluence series (0.09-5.4 J/cm²) were performed on the assumption of the endothelial damage thresholds. Untreated and riboflavin only corneas were used as controls. Animals were killed at 30 minutes and at 1 month after CXL. Corneas were harvested. Two-dimensional (2D) biomechanical testing was performed using a customized corneal holder in a commercially available stress-strain extensometer/indenter. Both elastic and viscoelastic analyses were performed. Statistical inference was performed using t-tests and specific mathematical models fitted to the experimental stress-strain and stress-relaxation data. Adjusted P values by the method of Benjamini and Hochberg are reported. For all CXL treatment groups, stress-relaxation showed significant differences (P < 0.0001) after 120 seconds of constant strain application, with cross-linked corneas maintaining a higher stress (441 ± 40 kPa) when compared with controls (337 ± 39 kPa). Stress-strain analysis confirmed these findings but was less sensitive to CXL-induced changes: at 0.5% of strain, cross-linked corneas remained at higher stress (778 ± 111 kPa) when compared with controls (659 ± 121 kPa). Cross-linking was induced in the mouse cornea in vivo, and its biomechanical effect successfully measured. This could create opportunities to study molecular pathways of CXL in transgenic mice.

Biomechanical comparison of four double-row speed-bridging rotator cuff repair techniques with or without medial or lateral row enhancement.

PubMed

Pauly, Stephan; Fiebig, David; Kieser, Bettina; Albrecht, Bjoern; Schill, Alexander; Scheibel, Markus

2011-12-01

Biomechanical comparison of four different Speed-Bridge configurations with or without medial or lateral row reinforcement. Reinforcement of the knotless Speed-Bridge double-row repair technique with additional medial mattress- or lateral single-stitches was hypothesized to improve biomechanical repair stability at time zero. Controlled laboratory study: In 36 porcine fresh-frozen shoulders, the infraspinatus tendons were dissected and shoulders were randomized to four groups: (1) Speed-Bridge technique with single tendon perforation per anchor (STP); (2) Speed-Bridge technique with double tendon perforation per anchor (DTP); (3) Speed-Bridge technique with medial mattress-stitch reinforcement (MMS); (4) Speed-Bridge technique with lateral single-stitch reinforcement (LSS). All repairs were cyclically loaded from 10-60 N up to 10-200 N (20 N stepwise increase) using a material testing device. Forces at 3 and 5 mm gap formation, mode of failure and maximum load to failure were recorded. The MMS-technique with double tendon perforation showed significantly higher ultimate tensile strength (338.9 ± 90.0 N) than DTP (228.3 ± 99.9 N), LSS (188.9 ± 62.5 N) and STP-technique (122.2 ± 33.8 N). Furthermore, the MMS-technique provided increased maximal force resistance until 3 and 5 mm gap formation (3 mm: 77.8 ± 18.6 N; 5 mm: 113.3 ± 36.1 N) compared with LSS, DTP and STP (P < 0.05 for each 3 and 5 mm gap formation). Failure mode was medial row defect by tendon sawing first, then laterally. No anchor pullout occurred. Double tendon perforation per anchor and additional medial mattress stitches significantly enhance biomechanical construct stability at time zero in this ex vivo model when compared with the all-knotless Speed-Bridge rotator cuff repair.

Biomechanical Testing of a 3-Hole versus a 4-Hole Sliding Hip Screw in the presence of a Retrograde Intramedullary Nail for Ipsilateral Intertrochanteric and Femur Shaft Fractures.

PubMed

Olsen, Michael; Goshulak, Peter; Crookshank, Meghan C; Moktar, Joel; Brazda, Ignace J; Schemitsch, Emil H; Zdero, Radovan

2018-04-03

The goal of this study was to compare a 3-hole vs. a 4-hole sliding hip screw (SHS) in the presence of a retrograde intramedullary (RIM) nail for fixing intertrochanteric and comminuted midshaft femur fractures. Mechanical tests were performed on 10 matched pairs of human cadaveric femurs that were osteotomized and then fixed using a 3-hole SHS vs. the traditional "gold standard" 4-hole SHS in the presence of a RIM nail. Data showed no differences between the 3-hole SHS with RIM nail vs. 4-hole SHS with RIM nail for stiffness (281 +/- 127 vs. 260 +/- 118 N/mm, p=0.76), clinical failure at 10 mm of hip displacement (2014 +/- 363 vs. 2134 +/- 614 N, p=0.52), or ultimate mechanical failure (3476 +/- 776 vs. 3669 +/- 755 N, p=0.12). For this fracture pattern, a 3-hole SHS with RIM nail may be a suitable surgical alternative to the traditional "gold standard" method, since it provides the same biomechanical properties while potentially reducing surgical time, blood loss, and hardware used. Level III biomechanical study.

Structured polarized light microscopy (SPLM) for mapping collagen fiber orientation of ocular tissues

NASA Astrophysics Data System (ADS)

Yang, Bin; Brazile, Bryn; Jan, Ning-Jiun; Voorhees, Andrew P.; Sigal, Ian A.

2018-02-01

Glaucoma is a disease characterized by progressive and irreversible vision loss leading to blindness. This vision loss is believed to be largely determined by the biomechanics of the optic nerve head region. Optic nerve head biomechanics, in turn, is determined by the properties of the constituent collagen. However, it is challenging to visualize and quantify collagen morphology and orientation in situ, and therefore often studies of the region collagen have used histological sections. Here we describe SPLM, a novel imaging technique that combines structured light illumination and polarized light microscopy (PLM) to enable collagen fiber visualization and fiber orientation mapping without requiring tissue sectioning. We developed a custom automated SPLM imaging system based on an upright microscope and a digital micromirror device (DMD) projector. The high spatial frequency patterns were used to achieve effective background suppression. Enhanced scattering sensitivity with SPLM resulted in images with highly improved visibility of collagen structures, even of tissues covered by pigment. SPLM produced improved fiber orientation maps from superficial layers compared to depth-averaged orientation from regular PLM. SPLM imaging provides valuable information of collagen fiber morphology and orientation in situ thus strengthening the study of ocular collagen fiber biomechanics and glaucoma.

Biomechanical outcome of proximal femoral nail antirotation is superior to proximal femoral locking compression plate for reverse oblique intertrochanteric fractures: a biomechanical study of intertrochanteric fractures.

PubMed

Ma, Jian-Xiong; Wang, Jie; Xu, Wei-Guo; Yu, Jing-Tao; Yang, Yang; Ma, Xin-Long

2015-01-01

Reverse obliquity intertrochanteric fractures are a challenge for orthopedic surgeons. The optimal internal fixation for repairing this type of unstable intertrochanteric fractures remains controversial. This study aimed to compare the biomechanical properties in axial load and cyclical axial load of proximal femoral nail antirotation (PFNA) and proximal femoral locking compression plate (PFLCP) for fixation of reverse obliquity intertrochanteric fractures. Sixteen embalmed cadaver femurs were sawed to simulate reverse obliquity intertrochanteric fracture and instrumented with PFNA or PFLCP. Axial loads and axial cyclic loads were applied to the femoral head by an Instron tester. If the implant-femur constructs did not fail, axial failure load was added to the remaining implant-femur constructs. Mean axial stiffness for PFNA was 21.10% greater than that of PFLCP. Cyclic axial loading caused significantly less (p=0.022) mean irreversible deformation in PFNA (3.43 mm) than in PFLCP (4.34 mm). Significantly less (p=0.002) mean total deformation was detected in PFNA (6.16 mm) than in PFLCP (8.67 mm). For fixing reverse obliquity intertrochanteric fractures, PFNA is superior to PFLCP under axial load.

Biochemical markers of cartilage metabolism are associated with walking biomechanics 6-months following anterior cruciate ligament reconstruction.

PubMed

Pietrosimone, Brian; Loeser, Richard F; Blackburn, J Troy; Padua, Darin A; Harkey, Matthew S; Stanley, Laura E; Luc-Harkey, Brittney A; Ulici, Veronica; Marshall, Stephen W; Jordan, Joanne M; Spang, Jeffery T

2017-10-01

The purpose of our study was to determine the association between biomechanical outcomes of walking gait (peak vertical ground reaction force [vGRF], vGRF loading rate [vGRF-LR], and knee adduction moment [KAM]) 6 months following anterior cruciate ligament reconstruction (ACLR) and biochemical markers of serum type-II collagen turnover (collagen type-II cleavage product to collagen type-II C-propeptide [C2C:CPII]), plasma degenerative enzymes (matrix metalloproteinase-3 [MMP-3]), and a pro-inflammatory cytokine (interleukin-6 [IL-6]). Biochemical markers were evaluated within the first 2 weeks (6.5 ± 3.8 days) following ACL injury and again 6 months following ACLR in eighteen participants. All peak biomechanical outcomes were extracted from the first 50% of the stance phase of walking gait during a 6-month follow-up exam. Limb symmetry indices (LSI) were used to normalize the biomechanical outcomes in the ACLR limb to that of the contralateral limb (ACLR/contralateral). Bivariate correlations were used to assess associations between biomechanical and biochemical outcomes. Greater plasma MMP-3 concentrations after ACL injury and at the 6-month follow-up exam were associated with lesser KAM LSI. Lesser KAM was associated with greater plasma IL-6 at the 6-month follow-up exam. Similarly, lesser vGRF-LR LSI was associated with greater plasma MMP-3 concentrations at the 6-month follow-up exam. Lesser peak vGRF LSI was associated with higher C2C:CPII after ACL injury, yet this association was not significant after accounting for walking speed. Therefore, lesser biomechanical loading in the ACLR limb, compared to the contralateral limb, 6 months following ACLR may be related to deleterious joint tissue metabolism that could influence future cartilage breakdown. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2288-2297, 2017. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Challenge of biomechanics.

PubMed

Volokh, K Y

2013-06-01

The application of mechanics to biology--biomechanics--bears great challenges due to the intricacy of living things. Their dynamism, along with the complexity of their mechanical response (which in itself involves complex chemical, electrical, and thermal phenomena) makes it very difficult to correlate empirical data with theoretical models. This difficulty elevates the importance of useful biomechanical theories compared to other fields of engineering. Despite inherent imperfections of all theories, a well formulated theory is crucial in any field of science because it is the basis for interpreting observations. This is all-the-more vital, for instance, when diagnosing symptoms, or planning treatment to a disease. The notion of interpreting empirical data without theory is unscientific and unsound. This paper attempts to fortify the importance of biomechanics and invigorate research efforts for those engineers and mechanicians who are not yet involved in the field. It is not aimed here, however, to give an overview of biomechanics. Instead, three unsolved problems are formulated to challenge the readers. At the micro-scale, the problem of the structural organization and integrity of the living cell is presented. At the meso-scale, the enigma of fingerprint formation is discussed. At the macro-scale, the problem of predicting aneurysm ruptures is reviewed. It is aimed here to attract the attention of engineers and mechanicians to problems in biomechanics which, in the author's opinion, will dominate the development of engineering and mechanics in forthcoming years.

Biomechanical Assessment of Locked Plating for the Fixation of Patella Fractures.

PubMed

Wurm, Simone; Augat, Peter; Bühren, Volker

2015-09-01

To analyze the mechanical stability of locked plating in comparison with tension-band wiring for the fixation of fractures of the patella. Biomechanical tests were performed on artificial foam patella specimens comparing an angular stable plate and monocortical screws with tension-band wiring. Tests were performed under combined tension and bending until failure simulating physiological loading of the tibia during walking. Tension-band wiring failed at 66% of the failure load of plating (1052 N, P = 0.002) and had 5 times larger fracture gap displacements (P = 0.002). Based on the biomechanical advantages, locked plating of the patella may constitute a reasonable alternative in the treatment of patella fractures.

Design and Validation of an Instrumented Uneven Terrain Treadmill.

PubMed

Voloshina, Alexandra S; Ferris, Daniel P

2018-06-01

Studying human and animal locomotion on an uneven terrain can be beneficial to basic science and applied studies for clinical and robotic applications. Traditional biomechanical analysis of human locomotion has often been limited to laboratory environments with flat, smooth runways and treadmills. The authors modified a regular exercise treadmill by attaching wooden blocks to the treadmill belt to yield an uneven locomotion surface. To ensure that these treadmill modifications facilitated biomechanical measurements, the authors compared ground reaction force data collected while a subject ran on the modified instrumented treadmill with a smooth surface with data collected using a conventional instrumented treadmill. Comparisons showed only minor differences. These results suggest that adding an uneven surface to a modified treadmill is a viable option for studying human or animal locomotion on an uneven terrain. Other types of surfaces (eg, compliant blocks) could be affixed in a similar manner for studies on other types of locomotion surfaces.

Recent microfluidic devices for studying gamete and embryo biomechanics.

PubMed

Lai, David; Takayama, Shuichi; Smith, Gary D

2015-06-25

The technical challenges of biomechanic research such as single cell analysis at a high monetary cost, labor, and time for just a small number of measurements is a good match to the strengths of microfluidic devices. New scientific discoveries in the fertilization and embryo development process, of which biomechanics is a major subset of interest, is crucial to fuel the continual improvement of clinical practice in assisted reproduction. The following review will highlight some recent microfluidic devices tailored for gamete and embryo biomechanics where biomimicry arises as a major theme of microfluidic device design and function, and the application of fundamental biomechanic principles are used to improve outcomes of cryopreservation. Copyright © 2015 Elsevier Ltd. All rights reserved.

The measurement of intracranial pressure and brain displacement due to short-duration dynamic overpressure loading

NASA Astrophysics Data System (ADS)

Iwaskiw, A. S.; Ott, K. A.; Armiger, R. S.; Wickwire, A. C.; Alphonse, V. D.; Voo, L. M.; Carneal, C. M.; Merkle, A. C.

2018-01-01

The experimental measurement of biomechanical responses that correlate with blast-induced traumatic brain injury (bTBI) has proven challenging. These data are critical for both the development and validation of computational and physical head models, which are used to quantify the biomechanical response to blast as well as to assess fidelity of injury mitigation strategies, such as personal protective equipment. Therefore, foundational postmortem human surrogate (PMHS) experimental data capturing the biomechanical response are necessary for human model development. Prior studies have measured short-duration pressure transmission to the brain (Kinetic phase), but have failed to reproduce and measure the longer-duration inertial loading that can occur (Kinematic phase). Four fully instrumented PMHS were subjected to short-duration dynamic overpressure in front-facing and rear-facing orientations, where intracranial pressure (ICP), global head kinematics, and brain motion (as measured by high-speed X-ray) with respect to the skull were recorded. Peak ICP results generally increased with increased dose, and a mirrored pressure response was seen when comparing the polarity of frontal bone versus occipital bone ICP sensors. The head kinematics were delayed when compared to the pressure response and showed higher peak angles for front-facing tests as compared to rear-facing. Brain displacements were approximately 2-6 mm, and magnitudes did not change appreciably between front- and rear-facing tests. These data will be used to inform and validate models used to assess bTBI.

Conceptual framework on the application of biomechanical measurement methods in driving behavior study

NASA Astrophysics Data System (ADS)

Sanjaya, Kadek Heri; Sya'bana, Yukhi Mustaqim Kusuma

2017-01-01

Research on eco-friendly vehicle development in Indonesia has largely neglected ergonomic study, despite the fact that traffic accidents have resulted in greater economic cost than fuel subsidy. We have performed a biomechanical experiment on human locomotion earlier. In this article, we describe the importance of implementing the biomechanical measurement methods in transportation ergonomic study. The instruments such as electromyogram (EMG), load cell, pressure sensor, and motion analysis methods as well as cross-correlation function analysis were explained, then the possibility of their application in driving behavior study is described. We describe the potentials and challenges of the biomechanical methods concerning the future vehicle development. The methods provide greater advantages in objective and accurate measurement not only in human task performance but also its correlation with vehicle performance.

Hop Distance Symmetry Does Not Indicate Normal Landing Biomechanics in Adolescent Athletes With Recent Anterior Cruciate Ligament Reconstruction.

PubMed

Wren, Tishya A L; Mueske, Nicole M; Brophy, Christopher H; Pace, J Lee; Katzel, Mia J; Edison, Bianca R; VandenBerg, Curtis D; Zaslow, Tracy L

2018-03-30

Study Design Retrospective cohort. Background Return to sport (RTS) protocols after anterior cruciate ligament reconstruction (ACLR) often include assessment of hop distance symmetry. However, it is unclear if movement deficits are present regardless of hop symmetry. Objectives To assess biomechanics and symmetry of adolescent athletes following ACLR during a single leg hop for distance. Methods Forty-six patients with ACLR (5-12 months post-surgery; 27 female; age 15.6, SD 1.7 years) were classified as asymmetric (operative limb hop distance <90% of non-operative limb; n=17) or symmetric (n=29). Lower extremity biomechanics were compared among operative and contralateral limbs and 24 symmetric controls (12 female; age 14.7, SD 1.5 years) using ANOVA. Results Compared to controls, asymmetric patients hopped a shorter distance on their operative limb (P<0.001), while symmetric patients hopped an intermediate distance on both sides (P≥0.12). During landing, operative limbs, regardless of hop distance, exhibited lower knee flexion moments compared to controls and the contralateral side (P≤0.04) with lower knee energy absorption than the contralateral side (P≤0.006). During take-off, both symmetric and asymmetric patients had less hip extension and smaller ankle range of motion on the operative side compared with controls (P≤0.05). Asymmetric patients also had lower hip range of motion on the operative, compared with the contralateral, side (P=0.001). Conclusion Both symmetric and asymmetric patients offloaded the operative knee; symmetric patients achieved symmetry in part by hopping a shorter distance on the contralateral side. Therefore, hop distance symmetry may not be an adequate test of single limb function and RTS readiness. Level of Evidence 2b. J Orthop Sports Phys Ther, Epub 30 Mar 2018. doi:10.2519/jospt.2018.7817.

Biomechanical measurements of stiffness and strength for five types of whole human and artificial humeri.

PubMed

Aziz, Mina S R; Nicayenzi, Bruce; Crookshank, Meghan C; Bougherara, Habiba; Schemitsch, Emil H; Zdero, Radovan

2014-05-01

The human humerus is the third largest longbone and experiences 2-3% of all fractures. Yet, almost no data exist on its intact biomechanical properties, thus preventing researchers from obtaining a full understanding of humerus behavior during injury and after being repaired with fracture plates and nails. The aim of this experimental study was to compare the biomechanical stiffness and strength of "gold standard" fresh-frozen humeri to a variety of humerus models. A series of five types of intact whole humeri were obtained: human fresh-frozen (n = 19); human embalmed (n = 18); human dried (n = 15); artificial "normal" (n = 12); and artificial "osteoporotic" (n = 12). Humeri were tested under "real world" clinical loading modes for shear stiffness, torsional stiffness, cantilever bending stiffness, and cantilever bending strength. After removing geometric effects, fresh-frozen results were 585.8 ± 181.5 N/mm2 (normalized shear stiffness); 3.1 ± 1.1 N/(mm2 deg) (normalized torsional stiffness); 850.8 ± 347.9 N/mm2 (normalized cantilever stiffness); and 8.3 ± 2.7 N/mm2 (normalized cantilever strength). Compared to fresh-frozen values, statistical equivalence (p ≥ 0.05) was obtained for all four test modes (embalmed humeri), 1 of 4 test modes (dried humeri), 1 of 4 test modes (artificial "normal" humeri), and 1 of 4 test modes (artificial "osteoporotic" humeri). Age and bone mineral density versus experimental results had Pearson linear correlations ranging from R = -0.57 to 0.80. About 77% of human humeri failed via a transverse or oblique distal shaft fracture, whilst 88% of artificial humeri failed with a mixed transverse + oblique fracture. To date, this is the most comprehensive study on the biomechanics of intact human and artificial humeri and can assist researchers to choose an alternate humerus model that can substitute for fresh-frozen humeri.

Do exercises used in injury prevention programmes modify cutting task biomechanics? A systematic review with meta-analysis.

PubMed

Pappas, Evangelos; Nightingale, Elizabeth J; Simic, Milena; Ford, Kevin R; Hewett, Timothy E; Myer, Gregory D

2015-05-01

Some injury prevention programmes aim to reduce the risk of ACL rupture. Although the most common athletic task leading to ACL rupture is cutting, there is currently no consensus on how injury prevention programmes influence cutting task biomechanics. To systematically review and synthesise the scientific literature regarding the influence of injury prevention programme exercises on cutting task biomechanics. The three largest databases (Medline, EMBASE and CINAHL) were searched for studies that investigated the effect of injury prevention programmes on cutting task biomechanics. When possible meta-analyses were performed. Seven studies met the inclusion criteria. Across all studies, a total of 100 participants received exercises that are part of ACL injury prevention programmes and 76 participants served in control groups. Most studies evaluated variables associated with the quadriceps dominance theory. The meta-analysis revealed decreased lateral hamstrings electromyography activity (p ≤ 0.05) while single studies revealed decreased quadriceps and increased medial hamstrings activity and decreased peak knee flexion moment. Findings from single studies reported that ACL injury prevention exercises reduce neuromuscular deficits (knee valgus moment, lateral trunk leaning) associated with the ligament and trunk dominance theories, respectively. The programmes we analysed appear most effective when they emphasise individualised biomechanical technique correction and target postpubertal women. The exercises used in injury prevention programmes have the potential to improve cutting task biomechanics by ameliorating neuromuscular deficits linked to ACL rupture, especially when they emphasise individualised biomechanical technique correction and target postpubertal female athletes. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Highly crosslinked polyethylene: a safe alternative to conventional polyethylene for dual mobility cup mobile component. A biomechanical validation.

PubMed

Malatray, Matthieu; Roux, Jean-Paul; Gunst, Stanislas; Pibarot, Vincent; Wegrzyn, Julien

2017-03-01

Dual mobility cup (DMC) consists of a cobalt-chromium (CoCr) alloy cup articulated with a polyethylene (PE) mobile component capturing the femoral head in force using a snap-fit technique. This biomechanical study was the first to evaluate and compare the generation of cracks in the retentive area of DMC mobile components made of highly crosslinked PE (XLPE) or conventional ultra-high molecular weight PE (UHMWPE). Eighty mobile components designed for a 52-mm diameter Symbol® DMC (Dedienne Santé, Mauguio, France) and a 28-mm diameter femoral head were analyzed. Four groups of 20 mobile components were constituted according to the PE material: raw UHMWPE, sterilized UHMWPE, annealed XLPE and remelted XLPE. Ten mobile components in each group were impacted with a 28-mm diameter CoCr femoral head using a snap-fit technique. The occurrence, location and area of the cracks in the retentive area were investigated using micro-CT (Skyscan 1176®, Bruker, Aarsellar, Belgium) with a 35 μm nominal isotropic voxel size by two observers blinded to the PE material and impaction or not of the mobile components. Compared to conventional UHMWPE, the femoral head snap-fit did not generate more or wider cracks in the retentive area of annealed or remelted XLPE mobile components. This biomechanical study suggests that XLPE in DMC could be a safe alternative to conventional UHMWPE regarding the generation of cracks in the retentive area related to the femoral head snap-fit.

Button fixation technique for Achilles tendon reinsertion: a biomechanical study.

PubMed

Awogni, David; Chauvette, Guillaume; Lemieux, Marie-Line; Balg, Frédéric; Langelier, Ève; Allard, Jean-Pascal

2014-01-01

Chronic insertional tendinopathy of the Achilles tendon is a frequent and disabling pathologic entity. Operative treatment is indicated for patients for whom nonoperative management has failed. The treatment can consist of the complete detachment of the tendon insertion and extensive debridement. We biomechanically tested a new operative technique that uses buttons for fixation of the Achilles tendon insertion on the posterior calcaneal tuberosity and compared it with 2 standard bone anchor techniques. A total of 40 fresh-frozen cadaver specimens were used to compare 3 fixation techniques for reinserting the Achilles tendon: single row anchors, double row anchors, and buttons. The ultimate loads and failure mechanisms were recorded. The button assembly (median load 764 N, range 713 to 888) yielded a median fixation strength equal to 202% (range 137% to 251%) of that obtained with the double row anchors (median load 412 N, range 301 to 571) and 255% (range 213% to 317%) of that obtained with the single row anchors (median load 338 N, range 241 to 433N). The most common failure mechanisms were suture breakage with the buttons (55%) and pull out of the implant with the double row (70%) and single row (85%) anchors. The results of the present biomechanical cadaver study have shown that Achilles tendon reinsertion fixation using the button technique provides superior pull out strength than the bone anchors tested. Copyright © 2014 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

A comparison of gait biomechanics of flip-flops, sandals, barefoot and shoes.

PubMed

Zhang, Xiuli; Paquette, Max R; Zhang, Songning

2013-11-06

Flip-flops and sandals are popular choices of footwear due to their convenience. However, the effects of these types of footwear on lower extremity biomechanics are still poorly understood. Therefore, the objective of this study was to investigate differences in ground reaction force (GRF), center of pressure (COP) and lower extremity joint kinematic and kinetic variables during level-walking in flip-flops, sandals and barefoot compared to running shoes. Ten healthy males performed five walking trials in the four footwear conditions at 1.3 m/s. Three-dimensional GRF and kinematic data were simultaneously collected. A smaller loading rate of the 1st peak vertical GRF and peak propulsive GRF and greater peak dorsiflexion moment in early stance were found in shoes compared to barefoot, flip-flops and sandals. Barefoot walking yielded greater mediolateral COP displacement, flatter foot contact angle, increased ankle plantarflexion contact angle, and smaller knee flexion contact angle and range of motion compared to all other footwear. The results from this study indicate that barefoot, flip-flops and sandals produced different peak GRF variables and ankle moment compared to shoes while all footwear yield different COP and ankle and knee kinematics compared to barefoot. The findings may be helpful to researchers and clinicians in understanding lower extremity mechanics of open-toe footwear.

The feet in systemic lupus erythematosus; are we underestimating their involvement and functional impact?

PubMed

Morales-Lozano, Rosario; Martínez-Barrio, Julia; González-Fernández, María Luz; López-Longo, Francisco Javier; Ovalles-Bonilla, Juan Gabriel; Valor, Lara; Janta, Iustina; Nieto, Juan Carlos; Hernández-Flórez, Diana; González, Carlos M; Monteagudo, Indalecio; Garrido, Jesús; Carreño, Luis; Naredo, Esperanza

2016-01-01

To evaluate biomechanical and ultrasound (US) abnormalities in SLE patients as compared with controls and to assess the relationship between these abnormalities and SLE activity. Fifty-four consecutive female patients with SLE with and without foot pain and 60 female controls (30 with foot pain and 30 without foot pain) were recruited. SLE activity was assessed by the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). SLE patients and controls blindly underwent a comprehensive podiatric, biomechanical and US evaluation of the feet. US assessment included detection of B-mode synovitis, tenosynovitis, enthesopathy, bone changes and synovial, tenosynovial and entheseal power Doppler (PD) signal. Thirty-one (57.4%) SLE patients had bilateral foot pain and 5 (9.3%) had unilateral foot pain. Metatarsalgia was the most common location for pain but without significant difference between groups (p=0.284). Toe joint deformities were significantly more common in SLE feet as compared with control feet (p<0.0005). SLE feet showed significantly more biomechanical abnormalities than control feet (p<0.05). B-mode synovitis in the tibiotalar joint was strongly associated with having SLE (p<0.0005) and the presence of synovial PD signal in the MTP joints was found only in painful feet of SLE patients. SLEDAI was significantly higher in patients with foot pain than in those with painless feet (p=0.008). However, SLEDAI did not discriminate between patients with and without biomechanical or US abnormalities. SLE patients showed more biomechanical and US abnormalities in the feet than controls, which were not captured by standardised assessment of the disease activity.

Biomechanics of Artificial Disc Replacements Adjacent to a 2-Level Fusion in 4-Level Hybrid Constructs: An In Vitro Investigation

PubMed Central

Liao, Zhenhua; Fogel, Guy R.; Wei, Na; Gu, Hongsheng; Liu, Weiqiang

2015-01-01

Background The ideal procedure for multilevel cervical degenerative disc diseases remains controversial. Recent studies on hybrid surgery combining anterior cervical discectomy and fusion (ACDF) and artificial cervical disc replacement (ACDR) for 2-level and 3-level constructs have been reported in the literature. The purpose of this study was to estimate the biomechanics of 3 kinds of 4-level hybrid constructs, which are more likely to be used clinically compared to 4-level arthrodesis. Material/Methods Eighteen human cadaveric spines (C2–T1) were evaluated in different testing conditions: intact, with 3 kinds of 4-level hybrid constructs (hybrid C3–4 ACDR+C4–6 ACDF+C6–7ACDR; hybrid C3–5ACDF+C5–6ACDR+C6–7ACDR; hybrid C3–4ACDR+C4–5ACDR+C5–7ACDF); and 4-level fusion. Results Four-level fusion resulted in significant decrease in the C3–C7 ROM compared with the intact spine. The 3 different 4-level hybrid treatment groups caused only slight change at the instrumented levels compared to intact except for flexion. At the adjacent levels, 4-level fusion resulted in significant increase of contribution of both upper and lower adjacent levels. However, for the 3 hybrid constructs, significant changes of motion increase far lower than 4P at adjacent levels were only noted in partial loading conditions. No destabilizing effect or hypermobility were observed in any 4-level hybrid construct. Conclusions Four-level fusion significantly eliminated motion within the construct and increased motion at the adjacent segments. For all 3 different 4-level hybrid constructs, ACDR normalized motion of the index segment and adjacent segments with no significant hypermobility. Compared with the 4-level ACDF condition, the artificial discs in 4-level hybrid constructs had biomechanical advantages compared to fusion in normalizing adjacent level motion. PMID:26694835

Biomechanics of Artificial Disc Replacements Adjacent to a 2-Level Fusion in 4-Level Hybrid Constructs: An In Vitro Investigation.

PubMed

Liao, Zhenhua; Fogel, Guy R; Wei, Na; Gu, Hongsheng; Liu, Weiqiang

2015-12-23

BACKGROUND The ideal procedure for multilevel cervical degenerative disc diseases remains controversial. Recent studies on hybrid surgery combining anterior cervical discectomy and fusion (ACDF) and artificial cervical disc replacement (ACDR) for 2-level and 3-level constructs have been reported in the literature. The purpose of this study was to estimate the biomechanics of 3 kinds of 4-level hybrid constructs, which are more likely to be used clinically compared to 4-level arthrodesis. MATERIAL AND METHODS Eighteen human cadaveric spines (C2-T1) were evaluated in different testing conditions: intact, with 3 kinds of 4-level hybrid constructs (hybrid C3-4 ACDR+C4-6 ACDF+C6-7ACDR; hybrid C3-5ACDF+C5-6ACDR+C6-7ACDR; hybrid C3-4ACDR+C4-5ACDR+C5-7ACDF); and 4-level fusion. RESULTS Four-level fusion resulted in significant decrease in the C3-C7 ROM compared with the intact spine. The 3 different 4-level hybrid treatment groups caused only slight change at the instrumented levels compared to intact except for flexion. At the adjacent levels, 4-level fusion resulted in significant increase of contribution of both upper and lower adjacent levels. However, for the 3 hybrid constructs, significant changes of motion increase far lower than 4P at adjacent levels were only noted in partial loading conditions. No destabilizing effect or hypermobility were observed in any 4-level hybrid construct. CONCLUSIONS Four-level fusion significantly eliminated motion within the construct and increased motion at the adjacent segments. For all 3 different 4-level hybrid constructs, ACDR normalized motion of the index segment and adjacent segments with no significant hypermobility. Compared with the 4-level ACDF condition, the artificial discs in 4-level hybrid constructs had biomechanical advantages compared to fusion in normalizing adjacent level motion.

The influence of matching populations on kinematic and kinetic variables in runners with iliotibial band syndrome.

PubMed

Grau, Stefan; Maiwald, Christian; Krauss, Inga; Axmann, Detlef; Horstmann, Thomas

2008-12-01

The purpose of this study was to assess how participant matching influences biomechanical variables when comparing healthy runners and runners with iliotibial band syndrome (ITBS). We examined 52 healthy runners (CO) and 18 with ITBS, using three-dimensional kinematics and pressure distribution. The study population was matched in three ways and compared with the biomechanical findings: ITBS versus CO I (unmatched), ITBS versus CO II (matched to gender) and ITBS versus CO III (matched to gender height, and weight). The final number of participants in each group was n = 18. The kinematic variables showed a dependency on the matching process. The largest statistically significant differences (after Bonferroni adjustment) in the frontal and transverse planes were between ITBS and CO III (p = .008). Pressure measurements were also dependent on the matching process, with decreasing and nonsignificant differences (p = .006) between ITBS and CO after refining the process (ITBS vs. CO III). The results of this study and the necessity of matching seem to be plausible (lever arms, different running styles). Data matching is important for understanding overuse injuries in running.

Biomechanical comparison of straight DCP and helical plates for fixation of transverse and oblique bone fractures.

PubMed

Aksakal, Bunyamin; Gurger, Murat; Say, Yakup; Yilmaz, Erhan

2014-01-01

Biomechanical comparison of straight DCP and helical plates for fixation of transversal and oblique tibial bone fractures were analyzed and compared to each other by axial compression, bending and torsion tests. An in vitro osteosynthesis of transverse (TF) and oblique bone fracture (OF) fixations have been analysed on fresh sheep tibias by using the DCP and helical compression plates (HP). Statistically significant differences were found for both DCP and helical plate fixations under axial compression, bending and torsional loads. The strength of fixation systems was in favor of DC plating with exception of the TF-HP fixation group under compression loads and torsional moments. The transvers fracture (TF) stability was found to be higher than that found in oblique fracture (OF) fixed by helical plates (HP). However, under torsional testing, compared to conventional plating, the helical plate fixations provided a higher torsional resistance and strength. The maximum stiffness at axial compression loading and maximum torsional strength was achieved in torsional testing for the TF-HP fixations. From in vitro biomechanical analysis, fracture type and plate fixation system groups showed different responses under different loadings. Consequently, current biomechanical analyses may encourage the usage of helical HP fixations in near future during clinical practice for transverse bone fractures.

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.

The Influence of Matching Populations on Kinematic and Kinetic Variables in Runners with Iliotibial Band Syndrome

ERIC Educational Resources Information Center

Grau, Stefan; Maiwald, Christian; Krauss, Inga; Axmann, Detlef; Horstmann, Thomas

2008-01-01

The purpose of this study was to assess how participant matching influences biomechanical variables when comparing healthy runners and runners with iliotibial band syndrome (ITBS). We examined 52 healthy runners (CO) and 18 with ITBS, using three-dimensional kinematics and pressure distribution. The study population was matched in three ways and…

Cardiac findings in Quarter Horses with heritable equine regional dermal asthenia.

PubMed

Brinkman, Erin L; Weed, Benjamin C; Patnaik, Sourav S; Brazile, Bryn L; Centini, Ryan M; Wills, Robert W; Olivier, Bari; Sledge, Dodd G; Cooley, Jim; Liao, Jun; Rashmir-Raven, Ann M

2017-03-01

OBJECTIVE To compare biomechanical and histologic features of heart valves and echocardiographic findings between Quarter Horses with and without heritable equine regional dermal asthenia (HERDA). DESIGN Prospective case-control study. ANIMALS 41 Quarter Horses. PROCEDURES Ultimate tensile strength (UTS) of aortic and mitral valve leaflets was assessed by biomechanical testing in 5 horses with HERDA and 5 horses without HERDA (controls). Histologic evaluation of aortic and mitral valves was performed for 6 HERDA-affected and 3 control horses. Echocardiography was performed in 14 HERDA-affected and 11 control horses. Biomechanical data and echocardiographic variables of interest were compared between groups by statistical analyses, RESULTS Mean values for mean and maximum UTS of heart valves were significantly lower in HERDA-affected horses than in controls. Blood vessels were identified in aortic valve leaflets of HERDA-affected but not control horses. Most echocardiographic data did not differ between groups. When the statistical model for echocardiographic measures was controlled for body weight, mean and maximum height and width of the aorta at the valve annulus in short-axis images were significantly associated with HERDA status and were smaller for affected horses. CONCLUSIONS AND CLINICAL RELEVANCE Lower UTS of heart valves in HERDA-affected horses, compared with those of control horses, supported that tissues other than skin with high fibrillar collagen content are abnormal in horses with HERDA. Lack of significant differences in most echocardiographic variables between affected and control horses suggested that echocardiography may not be useful to detect a substantial loss of heart valve tensile strength. Further investigation is warranted to confirm these findings. Studies in horses with HERDA may provide insight into cardiac abnormalities in people with collagen disorders.

Biomechanical implications of walking with indigenous footwear

PubMed Central

Willems, Catherine; Stassijns, Gaetane; Cornelis, Wim; D'Août, Kristiaan

2017-01-01

Abstract Objectives This study investigates biomechanical implications of walking with indigenous “Kolhapuri” footwear compared to barefoot walking among a population of South Indians. Materials and methods Ten healthy adults from South India walked barefoot and indigenously shod at voluntary speed on an artificial substrate. The experiment was repeated outside, on a natural substrate. Data were collected from (1) a heel‐mounted 3D‐accelerometer recording peak impact at heel contact, (2) an ankle‐mounted 3D‐goniometer (plantar/dorsiflexion and inversion/eversion), and (3) sEMG electrodes at the m. tibialis anterior and the m. gastrocnemius medialis. Results Data show that the effect of indigenous footwear on the measured variables, compared to barefoot walking, is relatively small and consistent between substrates (even though subjects walked faster on the natural substrate). Walking barefoot, compared to shod walking yields higher impact accelerations, but the differences are small and only significant for the artificial substrate. The main rotations of the ankle joint are mostly similar between conditions. Only the shod condition shows a faster ankle rotation over the rapid eversion motion on the natural substrate. Maximal dorsiflexion in late stance differs between the footwear conditions on an artificial substrate, with the shod condition involving a less dorsiflexed ankle, and the plantar flexion at toe‐off is more extreme when shod. Overall the activity pattern of the external foot muscles is similar. Discussion The indigenous footwear studied (Kolhapuri) seems to alter foot biomechanics only in a subtle way. While offering some degree of protection, walking in this type of footwear resembles barefoot gait and this type of indigenous footwear might be considered “minimal”. PMID:28101944

Cumulative loads increase at the knee joint with slow-speed running compared to faster running: a biomechanical study.

PubMed

Petersen, Jesper; Sørensen, Henrik; Nielsen, Rasmus Østergaard

2015-04-01

Biomechanical cross-sectional study. To investigate the hypothesis that the cumulative load at the knee during running increases as running speed decreases. The knee joint load per stride decreases as running speed decreases. However, by decreasing running speed, the number of strides per given distance is increased. Running a given distance at a slower speed may increase the cumulative load at the knee joint compared with running the same distance at a higher speed, hence increasing the risk of running-related injuries in the knee. Kinematic and ground reaction force data were collected from 16 recreational runners, during steady-state running with a rearfoot strike pattern at 3 different speeds (mean ± SD): 8.02 ± 0.17 km/h, 11.79 ± 0.21 km/h, and 15.78 ± 0.22 km/h. The cumulative load (cumulative impulse) over a 1000-m distance was calculated at the knee joint on the basis of a standard 3-D inverse-dynamics approach. Based on a 1000-m running distance, the cumulative load at the knee was significantly higher at a slow running speed than at a high running speed (relative difference, 80%). The mean load per stride at the knee increased significantly across all biomechanical parameters, except impulse, following an increase in running speed. Slow-speed running decreases knee joint loads per stride and increases the cumulative load at the knee joint for a given running distance compared to faster running. The primary reason for the increase in cumulative load at slower speeds is an increase in number of strides needed to cover the same distance.

Biomechanical implications of walking with indigenous footwear.

PubMed

Willems, Catherine; Stassijns, Gaetane; Cornelis, Wim; D'Août, Kristiaan

2017-04-01

This study investigates biomechanical implications of walking with indigenous "Kolhapuri" footwear compared to barefoot walking among a population of South Indians. Ten healthy adults from South India walked barefoot and indigenously shod at voluntary speed on an artificial substrate. The experiment was repeated outside, on a natural substrate. Data were collected from (1) a heel-mounted 3D-accelerometer recording peak impact at heel contact, (2) an ankle-mounted 3D-goniometer (plantar/dorsiflexion and inversion/eversion), and (3) sEMG electrodes at the m. tibialis anterior and the m. gastrocnemius medialis. Data show that the effect of indigenous footwear on the measured variables, compared to barefoot walking, is relatively small and consistent between substrates (even though subjects walked faster on the natural substrate). Walking barefoot, compared to shod walking yields higher impact accelerations, but the differences are small and only significant for the artificial substrate. The main rotations of the ankle joint are mostly similar between conditions. Only the shod condition shows a faster ankle rotation over the rapid eversion motion on the natural substrate. Maximal dorsiflexion in late stance differs between the footwear conditions on an artificial substrate, with the shod condition involving a less dorsiflexed ankle, and the plantar flexion at toe-off is more extreme when shod. Overall the activity pattern of the external foot muscles is similar. The indigenous footwear studied (Kolhapuri) seems to alter foot biomechanics only in a subtle way. While offering some degree of protection, walking in this type of footwear resembles barefoot gait and this type of indigenous footwear might be considered "minimal". © 2017 The Authors American Journal of Physical Anthropology Published by Wiley Periodicals, Inc.

ASB clinical biomechanics award winner 2006 prospective study of the biomechanical factors associated with iliotibial band syndrome.

PubMed

Noehren, Brian; Davis, Irene; Hamill, Joseph

2007-11-01

Iliotibial band syndrome is the leading cause of lateral knee pain in runners. Despite its high prevalence, little is known about the biomechanics that lead to this syndrome. The purpose of this study was to prospectively compare lower extremity kinematics and kinetics between a group of female runners who develop iliotibial band syndrome compared to healthy controls. It was hypothesized that runners who develop iliotibial band syndrome will exhibit greater peak hip adduction, knee internal rotation, rearfoot eversion and no difference in knee flexion at heel strike. Additionally, the iliotibial band syndrome group were expected to have greater hip abduction, knee external rotation, and rearfoot inversion moments. A group of healthy female recreational runners underwent an instrumented gait analysis and were then followed for two years. Eighteen runners developed iliotibial band syndrome. Their initial running mechanics were compared to a group of age and mileage matched controls with no history of knee or hip pain. Comparisons of peak hip, knee, rearfoot angles and moments were made during the stance phase of running. Variables of interest were averaged over the five running trials, and then averaged across groups. The iliotibial band syndrome group exhibited significantly greater hip adduction and knee internal rotation. However, rearfoot eversion and knee flexion were similar between groups. There were no differences in moments between groups. The development of iliotibial band syndrome appears to be related to increased peak hip adduction and knee internal rotation. These combined motions may increase iliotibial band strain causing it to compress against the lateral femoral condyle. These data suggest that treatment interventions should focus on controlling these secondary plane movements through strengthening, stretching and neuromuscular re-education.

Enhanced Combined Tomography and Biomechanics Data for Distinguishing Forme Fruste Keratoconus.

PubMed

Luz, Allan; Lopes, Bernardo; Hallahan, Katie M; Valbon, Bruno; Ramos, Isaac; Faria-Correia, Fernando; Schor, Paulo; Dupps, William J; Ambrósio, Renato

2016-07-01

To evaluate the performance of the Ocular Response Analyzer (ORA) (Reichert Ophthalmic Instruments, Depew, NY) variables and Pentacam HR (Oculus Optikgeräte GmbH, Wetzlar, Germany) tomographic parameters in differentiating forme fruste keratoconus (FFKC) from normal corneas, and to assess a combined biomechanical and tomographic parameter to improve outcomes. Seventy-six eyes of 76 normal patients and 21 eyes of 21 patients with FFKC were included in the study. Fifteen variables were derived from exported ORA signals to characterize putative indicators of biomechanical behavior and 37 ORA waveform parameters were tested. Sixteen tomographic parameters from Pentacam HR were tested. Logistic regression was used to produce a combined biomechanical and tomography linear model. Differences between groups were assessed by the Mann-Whitney U test. The area under the receiver operating characteristics curve (AUROC) was used to compare diagnostic performance. No statistically significant differences were found in age, thinnest point, central corneal thickness, and maximum keratometry between groups. Twenty-one parameters showed significant differences between the FFKC and control groups. Among the ORA waveform measurements, the best parameters were those related to the area under the first peak, p1area1 (AUROC, 0.717 ± 0.065). Among the investigator ORA variables, a measure incorporating the pressure-deformation relationship of the entire response cycle was the best predictor (hysteresis loop area, AUROC, 0.688 ± 0.068). Among tomographic parameters, Belin/Ambrósio display showed the highest predictive value (AUROC, 0.91 ± 0.057). A combination of parameters showed the best result (AUROC, 0.953 ± 0.024) outperforming individual parameters. Tomographic and biomechanical parameters demonstrated the ability to differentiate FFKC from normal eyes. A combination of both types of information further improved predictive value. [J Refract Surg. 2016;32(7):479-485.]. Copyright 2016, SLACK Incorporated.

Effect of femtosecond and microkeratome flaps creation on the cornea biomechanics during laser in situ keratomileusis: one year follow-up

PubMed Central

Sun, Qian; Deng, Zheng-Zheng; Zhou, Yue-Hua; Zhang, Jing; Peng, Xiao-Yan

2016-01-01

AIM To compare the corneal biomechanical outcomes at one year after laser in situ keratomileusis (LASIK) with the flaps created by Ziemer and Moria M2 microkeratome with 110 head and -20 blade. METHODS Totally 100 eyes of 50 consecutive patients were enrolled in this prospective study and divided into two groups for corneal flaps created by ZiemerFemto LDV and Moria M2 microkeratome with 110 head and -20 blade. Corneal biomechanical properties including cornea resistance factor (CRF) and cornea hysteresis (CH) were measured before and 1, 3, 6, 12mo after surgery by ocular response analyzer. Central cornea thickness and corneal flap thickness were measured by optical coherence tomography. RESULTS The ablation depth (P=0.693), residual corneal thickness (P=0.453), and postoperative corneal curvature (P=0.264) were not significant different between Ziemer group and Moria 110-20 group after surgery. The residual stromal bed thickness, corneal flap thickness, CH and CRF at 12mo after surgery were significant different between Ziemer group and Moria 110-20 group (P<0.01);Ziemer group gained better corneal biomechanical results. The CRF and CH increased gradually from 1 to 12mo after surgery in Ziemer group, increased from 1 to 6mo but decreased from 6 to 12mo in Moria 110-20 group. Both CRF and CH at one year after surgery increased with the increasing of residual cornea thickness; pre-LASIK CRF, CRF also increased with residual stromal bed thickness, while CH decreased with the increasing of pre-LASIK intraocular pressure and cornea flap thickness (P<0.01). CONCLUSION In one year follow-up, femtosecond laser can provide better cornea flaps with stable cornea biomechanics than mechanical microkeratome. PMID:27803856

Effects of Plantar Vibration on Bone and Deep Fascia in a Rat Hindlimb Unloading Model of Disuse

PubMed Central

Huang, Yunfei; Fan, Yubo; Salanova, Michele; Yang, Xiao; Sun, Lianwen; Blottner, Dieter

2018-01-01

The deep fascia of the vertebrate body comprises a biomechanically unique connective cell and tissue layer with integrative functions to support global and regional strain, tension, and even muscle force during motion and performance control. However, limited information is available on deep fascia in relation to bone in disuse. We used rat hindlimb unloading as a model of disuse (21 days of hindlimb unloading) to study biomechanical property as well as cell and tissue changes to deep fascia and bone unloading. Rats were randomly divided into three groups (n = 8, each): hindlimb unloading (HU), HU + vibration (HUV), and cage-control (CON). The HUV group received local vibration applied to the plantar of both hind paws. Micro-computed tomography analyzed decreased bone mineral density (BMD) of vertebra, tibia, and femur in HU vs. CON. Biomechanical parameters (elastic modulus, max stress, yield stress) of spinal and crural fascia in HU were always increased vs. CON. Vibration in HUV only counteracted HU-induced tibia bone loss and crural fascia mechanical changes but failed to show comparable changes in the vertebra and spinal fascia on lumbar back. Tissue and cell morphometry (size and cell nuclear density), immunomarker intensity levels of anti-collagen-I and III, probed on fascia cryosections well correlated with biomechanical changes suggesting crural fascia a prime target for plantar vibration mechano-stimulation in the HU rat. We conclude that the regular biomechanical characteristics as well as tissue and cell properties in crural fascia and quality of tibia bone (BMD) were preserved by local plantar vibration in disuse suggesting common mechanisms in fascia and bone adaptation to local mechanovibration stimulation following hind limb unloading in the HUV rat. PMID:29875702

Effects of Plantar Vibration on Bone and Deep Fascia in a Rat Hindlimb Unloading Model of Disuse.

PubMed

Huang, Yunfei; Fan, Yubo; Salanova, Michele; Yang, Xiao; Sun, Lianwen; Blottner, Dieter

2018-01-01

The deep fascia of the vertebrate body comprises a biomechanically unique connective cell and tissue layer with integrative functions to support global and regional strain, tension, and even muscle force during motion and performance control. However, limited information is available on deep fascia in relation to bone in disuse. We used rat hindlimb unloading as a model of disuse (21 days of hindlimb unloading) to study biomechanical property as well as cell and tissue changes to deep fascia and bone unloading. Rats were randomly divided into three groups ( n = 8, each): hindlimb unloading (HU), HU + vibration (HUV), and cage-control (CON). The HUV group received local vibration applied to the plantar of both hind paws. Micro-computed tomography analyzed decreased bone mineral density (BMD) of vertebra, tibia, and femur in HU vs. CON. Biomechanical parameters (elastic modulus, max stress, yield stress) of spinal and crural fascia in HU were always increased vs. CON. Vibration in HUV only counteracted HU-induced tibia bone loss and crural fascia mechanical changes but failed to show comparable changes in the vertebra and spinal fascia on lumbar back. Tissue and cell morphometry (size and cell nuclear density), immunomarker intensity levels of anti-collagen-I and III, probed on fascia cryosections well correlated with biomechanical changes suggesting crural fascia a prime target for plantar vibration mechano-stimulation in the HU rat. We conclude that the regular biomechanical characteristics as well as tissue and cell properties in crural fascia and quality of tibia bone (BMD) were preserved by local plantar vibration in disuse suggesting common mechanisms in fascia and bone adaptation to local mechanovibration stimulation following hind limb unloading in the HUV rat.

First delivery and ovariectomy affect biomechanical and structural properties of the vagina in the ovine model.

PubMed

Urbankova, Iva; Callewaert, Geertje; Blacher, Silvia; Deprest, Dries; Hympanova, Lucie; Feola, Andrew; De Landsheere, Laurent; Deprest, Jan

2018-01-08

Animal models are useful for investigating the genesis of pelvic floor dysfunction and for developing novel therapies for its treatment. There is a need for an alternative large-animal model to the nonhuman primate. Therefore we studied the effects of the first vaginal delivery, ovariectomy and systemic hormonal replacement therapy (HRT) on the biomechanical and structural properties of the ovine vagina. We examined the gross anatomical properties of nulliparous, primiparous, ovariectomized multiparous, and ovariectomized hormone-replaced multiparous sheep (six animals per group). We also harvested mid-vaginal and distal vaginal tissue to determine smooth muscle contractility and passive biomechanical properties, for morphometric assessment of the vaginal wall layers, to determine collagen and elastin content, and for immunostaining for α-smooth muscle actin and estrogen receptor-α. There were no regional differences in the nulliparous vagina. One year after the first vaginal delivery, stiffness and contractility of the distal vagina were decreased, whereas the elastin content increased. The mid-vagina of ovariectomized sheep was stiff, and its epithelium was thin and lacked glycogen. HRT decreased the stiffness of the mid-vagina by 45% but had no measurable effect on contractility or elastin content, and increased epithelial thickness and glycogen content. HRT also increased the epithelial thickness and glycogen content of the distal vagina. At this location, there were no changes in morphology or stiffness. In sheep, life events including delivery and ovariectomy affect the biomechanical properties of the vagina in a region-specific way. Vaginal delivery mainly affects the distal region by decreasing stiffness and contractility. HRT can reverse the increase in stiffness of the mid-vagina observed after surgical induction of menopause. These observations are in line with scanty biomechanical measurements in comparable clinical specimens.

[Evaluation of corneal biomechanics in keratoconus using dynamic ultra-high-speed Scheimpflug measurements].

PubMed

Brettl, S; Franko Zeitz, P; Fuchsluger, T A

2018-06-22

The in vivo analysis of corneal biomechanics in patients with keratoconus is especially of interest with respect to diagnosis, follow-up and monitoring of the disease. For a better understanding it is necessary to describe the potential of dynamic Scheimpflug measurements for the detection and interpretation of biomechanical changes in keratoconus. The current state of analyzing biomechanical changes in keratoconus with the Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) is described. This technique represents a new approach for understanding corneal biomechanics. Furthermore, it was investigated whether the device can biomechanically quantify a rigidity increasing effect of therapeutic UV-crosslinking and whether early stages of keratoconus can be detected using dynamic Scheimpflug analysis. In patients with keratoconus, the in vivo analysis of corneal biomechanics using dynamic Scheimpflug measurements as a supplementary procedure can be of advantage with respect to disease management. By optimization of screening of subclinical keratoconus stages, this method widens the analytic spectrum regarding diagnosis and follow-up of the disease; however, further studies are required to evaluate whether visual outcome of affected patients can be improved by earlier diagnosis.

Brillouin microscopy: assessing ocular tissue biomechanics.

PubMed

Yun, Seok Hyun; Chernyak, Dimitri

2018-07-01

Assessment of corneal biomechanics has been an unmet clinical need in ophthalmology for many years. Many researchers and clinicians have identified corneal biomechanics as source of variability in refractive procedures and one of the main factors in keratoconus. However, it has been difficult to accurately characterize corneal biomechanics in patients. The recent development of Brillouin light scattering microscopy heightens the promise of bringing biomechanics into the clinic. The aim of this review is to overview the progress and discuss prospective applications of this new technology. Brillouin microscopy uses a low-power near-infrared laser beam to determine longitudinal modulus or mechanical compressibility of tissue by analyzing the return signal spectrum. Human clinical studies have demonstrated significant difference in the elastic properties of normal corneas versus corneas diagnosed with mild and severe keratoconus. Clinical data have also shown biomechanical changes after corneal cross-linking treatment of keratoconus patients. Brillouin measurements of the crystalline lens and sclera have also been demonstrated. Brillouin microscopy is a promising technology under commercial development at present. The technique enables physicians to characterize the biomechanical properties of ocular tissues.

[Comparative efficacy of different regimens of locomotor training in long-term space flights by the data of biomechanical and electromyographic parametrs of walking].

PubMed

Shpakov, A V; Voronov, A V; Fomina, E V; Lysova, N Iu; Chernova, M V; Kozlovskaia, I B

2013-01-01

Biomechanical and electromyographic characteristics of locomotion were investigated before and after space flight on the 3rd, 7th and 10th day after landing in 18 cosmonauts--crewmembers of long-term ISS space flights. It was shown that microgravity causes the development of significant changes in biomechanical and electromyographic characteristics of walking. Decrease of the angular displacement amplitude in leg joints, reduction of the length of the double step, increase of the electromyographic cost of locomotion were recorded after flight. It was also shown that interval locomotor physical training in long-term space flights in the regimen of alternation running and walking prevents physiological cost of locomotor movements increase after space flight and provides more effective maintenance of the neuromuscular system functions after flight. After flight smaller changes of biomechanical and electromyographic characteristics of walking were observed in cosmonauts who used locomotor training in interval regimen.

Effect of multilevel lumbar disc arthroplasty on the operative- and adjacent-level kinematics and intradiscal pressures: an in vitro human cadaveric assessment.

PubMed

Dmitriev, Anton E; Gill, Norman W; Kuklo, Timothy R; Rosner, Michael K

2008-01-01

With lumbar arthroplasty gaining popularity, limited data are available highlighting changes in adjacent-level mechanics after multilevel procedures. Compare operative- and adjacent-segment range of motion (ROM) and intradiscal pressures (IDPs) after two-level arthroplasty versus circumferential arthrodesis. Cadaveric biomechanical study. Ten human cadaveric lumbar spines were used in this investigation. Biomechanical testing was performed according to a hybrid testing protocol using an unconstrained spine simulator under axial rotation (AR), flexion extension (FE), and lateral-bending (LB) loading. Specimens were tested in the following order: 1) Intact, 2) L3-L5 total disc replacement (TDR), 3) L3-L5 anterior interbody cages+pedicle screws. IDP was recorded at proximal and distal adjacent levels and normalized to controls (%intact). Full ROM was monitored at the operative and adjacent levels and reported in degrees. Kinematics assessment revealed L3-L5 ROM reduction after both reconstructions versus intact controls (p < .05). However, global quality of segmental motion distributed over L2-S1 was preserved in the arthroplasty group but was significantly altered after circumferential fixation. Furthermore, adjacent-level ROM was increased for the arthrodesis group under LB at both segments and during AR at L2-L3 relative to controls (p < .05). FE did not reveal any intergroup statistical differences. Nonetheless, after arthrodesis IDPs were increased proximally under all three loading modalities, whereas distally a significant IDP rise was noted during AR and LB (p < .05). No statistical differences in either biomechanical parameter were recorded at the adjacent levels between intact control and TDR groups. Our results indicate no significant adjacent-level biomechanical changes between arthroplasty and control groups. In contrast, significant alterations in ROM and IDP were recorded both proximally (ROM=LB & AR; IDP=AR, FE, LB) and distally (ROM=LB; IDP=AR & LB) after circumferential arthrodesis. Therefore, two-level lumbar arthroplasty maintains a more favorable biomechanical environment at the adjacent segments compared with the conventional transpedicular fixation technique. This, in turn, may have a positive effect on the rate of the transition syndrome postoperatively.

Comprehensive Assessment of Osteoporosis and Bone Fragility with CT Colonography

PubMed Central

Murthy, Naveen S.; Khosla, Sundeep; Clarke, Bart L.; Bruining, David H.; Kopperdahl, David L.; Lee, David C.; Keaveny, Tony M.

2016-01-01

Purpose To evaluate the ability of additional analysis of computed tomographic (CT) colonography images to provide a comprehensive osteoporosis assessment. Materials and Methods This Health Insurance Portability and Accountability Act–compliant study was approved by our institutional review board with a waiver of informed consent. Diagnosis of osteoporosis and assessment of fracture risk were compared between biomechanical CT analysis and dual-energy x-ray absorptiometry (DXA) in 136 women (age range, 43–92 years), each of whom underwent CT colonography and DXA within a 6-month period (between January 2008 and April 2010). Blinded to the DXA data, biomechanical CT analysis was retrospectively applied to CT images by using phantomless calibration and finite element analysis to measure bone mineral density and bone strength at the hip and spine. Regression, Bland-Altman, and reclassification analyses and paired t tests were used to compare results. Results For bone mineral density T scores at the femoral neck, biomechanical CT analysis was highly correlated (R2 = 0.84) with DXA, did not differ from DXA (P = .15, paired t test), and was able to identify osteoporosis (as defined by DXA), with 100% sensitivity in eight of eight patients (95% confidence interval [CI]: 67.6%, 100%) and 98.4% specificity in 126 of 128 patients (95% CI: 94.5%, 99.6%). Considering both the hip and spine, the classification of patients at high risk for fracture by biomechanical CT analysis—those with osteoporosis or “fragile bone strength”—agreed well against classifications for clinical osteoporosis by DXA (T score ≤−2.5 at the hip or spine), with 82.8% sensitivity in 24 of 29 patients (95% CI: 65.4%, 92.4%) and 85.7% specificity in 66 of 77 patients (95% CI: 76.2%, 91.8%). Conclusion Retrospective biomechanical CT analysis of CT colonography for colorectal cancer screening provides a comprehensive osteoporosis assessment without requiring changes in imaging protocols. © RSNA, 2015 Online supplemental material is available for this article. An earlier incorrect version of this article appeared online. This article was corrected on July 24, 2015. PMID:26200602

Augmentation of Distal Biceps Repair With an Acellular Dermal Graft Restores Native Biomechanical Properties in a Tendon-Deficient Model.

PubMed

Conroy, Christine; Sethi, Paul; Macken, Craig; Wei, David; Kowalsky, Marc; Mirzayan, Raffy; Pauzenberger, Leo; Dyrna, Felix; Obopilwe, Elifho; Mazzocca, Augustus D

2017-07-01

The majority of distal biceps tendon injuries can be repaired in a single procedure. In contrast, complete chronic tears with severe tendon substance deficiency and retraction often require tendon graft augmentation. In cases with extensive partial tears of the distal biceps, a human dermal allograft may be used as an alternative to restore tendon thickness and biomechanical integrity. Dermal graft augmentation will improve load to failure compared with nonaugmented repair in a tendon-deficient model. Controlled laboratory study. Thirty-six matched specimens were organized into 1 of 4 groups: native tendon, native tendon with dermal graft augmentation, tendon with an attritional defect, and tendon with an attritional defect repaired with a graft. To mimic a chronic attritional biceps lesion, a defect was created by a complete tear, leaving 30% of the tendon's width intact. The repair technique in all groups consisted of cortical button and interference screw fixation. All specimens underwent cyclical loading for 3000 cycles and were then tested to failure; gap formation and peak load at failure were documented. The mean (±SD) load to failure (320.9 ± 49.1 N vs 348.8 ± 77.6 N, respectively; P = .38) and gap formation (displacement) (1.8 ± 1.4 mm vs 1.6 ± 1.1 mm, respectively; P = .38) did not differ between the native tendon groups with and without graft augmentation. In the tendon-deficient model, the mean load to failure was significantly improved with graft augmentation compared with no graft augmentation (282.1 ± 83.8 N vs 199.7 ± 45.5 N, respectively; P = .04), while the mean gap formation was significantly reduced (1.2 ± 1.0 mm vs 2.7 ± 1.4 mm, respectively; P = .04). The mean load to failure of the deficient tendon with graft augmentation (282.1 N) compared with the native tendon (348.8 N) was not significantly different ( P = .12). This indicates that the native tendon did not perform differently from the grafted deficient tendon. In a tendon-deficient, complete distal biceps rupture model, acellular dermal allograft augmentation restored the native tendon's biomechanical properties at time zero. The grafted tissue-deficient model demonstrated no significant differences in the load to failure and gap formation compared with the native tendon. As expected, dermal augmentation of attritional tendon repair increased the load to failure and stiffness as well as decreased displacement compared with the ungrafted tissue-deficient model. Tendons with their native width showed no statistical difference or negative biomechanical consequences of dermal augmentation. Dermal augmentation of the distal biceps is a biomechanically feasible option for patients with an attritionally thinned-out tendon.

Observed Differences between Males and Females in Surgically Treated Carpal Tunnel Syndrome Among Non-manual Workers: A Sensitivity Analysis of Findings from a Large Population Study

PubMed Central

Farioli, Andrea; Curti, Stefania; Bonfiglioli, Roberta; Baldasseroni, Alberto; Spatari, Giovanna; Mattioli, Stefano; Violante, Francesco Saverio

2018-01-01

Abstract Objectives We aimed at assessing whether differences among males and females in carpal tunnel syndrome (CTS) epidemiology might be attributable to segregation with respect to occupational biomechanical exposures or differential access to care by sex. Methods We analysed surgically treated cases of CTS occurring among non-manual workers in Tuscany between 1997 and 2000. We conducted a Monte Carlo simulation to estimate the difference in occupational biomechanical exposures between males and females necessary to explain the observed incidence rate ratios. We also accounted for the sex-specific probability of receiving surgery after the diagnosis of CTS, as women were reported to be more likely to undergo surgery in a subset of our study population. We quantified the hypothetical biomechanical overload through the hand activity level (HAL) metric proposed by the American Conference of Governmental Industrial Hygienists. To quantify the effect of HAL on CTS risk, we assumed a prior distribution based on findings from two large cohort studies of industrial workers. Results After adjustment for the probability of receiving surgery, women showed a 4-fold incidence of CTS as compared with men. To explain this association among non-manual workers, women should have an average value of HAL at least 5 points higher. Conclusions Our analysis does not support the hypothesis that the difference in CTS incidence between males and females is entirely attributable to occupational risk factors or to differential access to surgery. The causal pathway between sex and CTS might include more determinants such as hormonal factors, anthropometric characteristics, and non-occupational exposure to biomechanical overload (e.g. household tasks). PMID:29579135

Neural space and biomechanical integrity of the developing cervical spine in compression.

PubMed

Nuckley, David J; Van Nausdle, Joseph A; Eck, Michael P; Ching, Randal P

2007-03-15

A factorial study design was used to examine the biomechanical and neuroprotective integrity of the cervical spine throughout maturation using a postmortem baboon model. To investigate changes with spinal development that affect the neuroprotective ability of the cervical spine in compressive loading. Child spinal cord injuries claim and debilitate thousands of children in the United States each year. Many of these injuries are diagnostically and mechanistically difficult to classify, treat, and prevent. Biomechanical studies on maturing spinal tissues have identified decreased stiffness and tolerance characteristics for children compared with adults. Unfortunately, while neurologic deficit typically dictates functional outcome, no previous studies have examined the neuroprotective role of the pediatric cervical spine. Twenty-two postmortem baboon cervical spines across the developmental age spectrum were tested. Two functional spinal unit segments (Oc-C2, C3-C5, and C6-T1) were instrumented with transducers to measure dynamic changes in the spinal canal. These tissues were compressed to 70% strain dynamically, and the resultant mechanics and spinal canal occlusions were recorded. Classic injury patterns were observed in all of the specimens tested. The compressive mechanics exhibited a significant age relationship (P < 0.0001). Furthermore, while the peak-percent spinal canal occlusion was not age dependent, the percent occlusion just before failure did demonstrate a significant decrease with advancing age (P = 0.0001). The neuroprotective ability of the cervical spine preceding failure appears to be age dependent, where the young spine can produce greater spinal canal occlusions without failure than its adult counterpart. The overall percent of the spinal canal occluded during a compression injury was not age dependent; however, these data reveal the neuroprotective ability of the child spine to be more sensitive as an injury predictor than the biomechanical fracture data.

Tribology studies of the natural knee using an animal model in a new whole joint natural knee simulator.

PubMed

Liu, Aiqin; Jennings, Louise M; Ingham, Eileen; Fisher, John

2015-09-18

The successful development of early-stage cartilage and meniscus repair interventions in the knee requires biomechanical and biotribological understanding of the design of the therapeutic interventions and their tribological function in the natural joint. The aim of this study was to develop and validate a porcine knee model using a whole joint knee simulator for investigation of the tribological function and biomechanical properties of the natural knee, which could then be used to pre-clinically assess the tribological performance of cartilage and meniscal repair interventions prior to in vivo studies. The tribological performance of standard artificial bearings in terms of anterior-posterior (A/P) shear force was determined in a newly developed six degrees of freedom tribological joint simulator. The porcine knee model was then developed and the tribological properties in terms of shear force measurements were determined for the first time for three levels of biomechanical constraints including A/P constrained, spring force semi-constrained and A/P unconstrained conditions. The shear force measurements showed higher values under the A/P constrained condition (predominantly sliding motion) compared to the A/P unconstrained condition (predominantly rolling motion). This indicated that the shear force simulation model was able to differentiate between tribological behaviours when the femoral and tibial bearing was constrained to slide or/and roll. Therefore, this porcine knee model showed the potential capability to investigate the effect of knee structural, biomechanical and kinematic changes, as well as different cartilage substitution therapies on the tribological function of natural knee joints. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Head Impact Biomechanics in Women's College Soccer.

PubMed

Lynall, Robert C; Clark, Michael D; Grand, Erin E; Stucker, Jaclyn C; Littleton, Ashley C; Aguilar, Alain J; Petschauer, Meredith A; Teel, Elizabeth F; Mihalik, Jason P

2016-09-01

There are limited nonlaboratory soccer head impact biomechanics data. This is surprising given soccer's global popularity. Epidemiological data suggest that female college soccer players are at a greater concussion injury risk than their male counterparts. Therefore, the purposes of our study were to quantify head impact frequency and magnitude during women's soccer practices and games in the National Collegiate Athletic Association and to characterize these data across event type, playing position, year on the team, and segment of game (first and second halves). Head impact biomechanics were collected from female college soccer players (n = 22; mean ± SD age = 19.1 ± 0.1 yr, height = 168.0 ± 3.5 cm, mass = 63.7 ± 6.0 kg). We employed a helmetless head impact measurement device (X2 Biosystems xPatch) before each competition and practice across a single season. Peak linear and rotational accelerations were categorized based on impact magnitude and subsequently analyzed using appropriate nonparametric analyses. Overall, women's college soccer players experience approximately seven impacts per 90 min of game play. The overwhelming majority (~90%) of all head impacts were categorized into our mildest linear acceleration impact classification (10g-20g). Interestingly, a higher percentage of practice impacts in the 20g-40g range compared with games (11% vs 7%) was observed. Head impact biomechanics studies have provided valuable insights into understanding collision sports and for informing evidence-based rule and policy changes. These have included changing the football kickoff, ice hockey body checking ages, and head-to-head hits in both sports. Given soccer's global popularity, and the growing public concern for the potential long-term neurological implications of collision and contact sports, studying soccer has the potential to impact many athletes and the sports medicine professionals caring for them.

Absorbable scaphoid screw development: a comparative study on biomechanics

PubMed Central

Wang, Yi; Song, Muguo; Xu, Yongqing; He, Xiaoqing; Zhu, YueLiang

2016-01-01

Background The scaphoid is critical for maintaining the stability and movement of the wrist joints. This study aimed to develop a new internal fixator absorbable scaphoid screw (ASS) for fixation of the scaphoid waist after fracture and to test the biomechanical characteristics of ASS. Materials and methods An ASS was prepared using polylactic acids and designed based on scaphoid measurements and anatomic features. Twenty fractured scaphoid waist specimens were randomly divided into experimental and control groups (n=10/group). Reduction and internal fixation of the scaphoid were achieved with either Kirschner wires (K-wires) or ASS. A moving target simulator was used to test palmar flexion and dorsal extension, with the range of testing (waist movement) set from 5° of palmar flexion to 25° of dorsal extension. Flexion and extension were repeated 2,000 times for each specimen. Fracture gap displacements were measured with a computerized tomography scanning. Scaphoid tensile and bending strengths were measured by using a hydraulic pressure biomechanical system. Results Prior to biomechanical fatigue testing, fracture gap displacements were 0.16±0.02 mm and 0.22±0.02 mm in the ASS and K-wire groups, respectively. After fatigue testing, fracture gap displacements in the ASS and the K-wire groups were 0.21±0.03 mm and 1.52±0.07 mm, respectively. The tensile strengths for the ASS and K-wire groups were 0.95±0.02 MPa and 0.63±0.02 MPa, respectively. Conclusion Fixation using an ASS provided sufficient mechanical support for the scaphoid after fracture. PMID:27217756

A numerical framework for studying the biomechanical behavior of abdominal aortic aneurysm

NASA Astrophysics Data System (ADS)

Jalalahmadi, Golnaz; Linte, Cristian; Helguera, María.

2017-03-01

Abdominal aortic aneurysm (AAA) is known as a leading cause of death in the United States. AAA is an abnormal dilation of the aorta, which usually occurs below the renal arteries and causes an expansion at least 1.5 times its normal diameter. It has been shown that biomechanical parameters of the aortic tissue coupled with a set of specific geometric parameters characterizing the vessel expansion, affect the risk of aneurysm rupture. Here, we developed a numerical framework that incorporates both biomechanical and geometrical factors to study the behavior of abdominal aortic aneurysm. Our workflow enables the extraction of the aneurysm geometry from both clinical quality, as well as low-resolution MR images. We used a two-parameter, hyper-elastic, isotropic, incompressible material to model the vessel tissue. Our numerical model was tested using both synthetic and mouse data and we evaluated the effects of the geometrical and biomechanical properties on the developed peak wall stress. In addition, we performed several parameter sensitivity studies to investigate the effect of different factors affecting the AAA and its behavior and rupture. Lastly, relationships between different geometrical and biomechanical parameters and peak wall stress were determined. These studies help us better understand vessel tissue response to various loading, geometry and biomechanics conditions, and we plan to further correlate these findings with the pathophysiological conditions from a patient population diagnosed with abdominal aortic aneurysms.

A comparison in a youth population between those with and without a history of concussion using biomechanical reconstruction.

PubMed

Post, Andrew; Hoshizaki, T Blaine; Gilchrist, Michael D; Koncan, David; Dawson, Lauren; Chen, Wesley; Ledoux, Andrée-Anne; Zemek, Roger

2017-04-01

OBJECTIVE Concussion is a common topic of research as a result of the short- and long-term effects it can have on the affected individual. Of particular interest is whether previous concussions can lead to a biomechanical susceptibility, or vulnerability, to incurring further head injuries, particularly for youth populations. The purpose of this research was to compare the impact biomechanics of a concussive event in terms of acceleration and brain strains of 2 groups of youths: those who had incurred a previous concussion and those who had not. It was hypothesized that the youths with a history of concussion would have lower-magnitude biomechanical impact measures than those who had never suffered a previous concussion. METHODS Youths who had suffered a concussion were recruited from emergency departments across Canada. This pool of patients was then separated into 2 categories based on their history of concussion: those who had incurred 1 or more previous concussions, and those who had never suffered a concussion. The impact event that resulted in the brain injury was reconstructed biomechanically using computational, physical, and finite element modeling techniques. The output of the events was measured in biomechanical parameters such as energy, force, acceleration, and brain tissue strain to determine if those patients who had a previous concussion sustained a brain injury at lower magnitudes than those who had no previously reported concussion. RESULTS The results demonstrated that there was no biomechanical variable that could distinguish between the concussion groups with a history of concussion versus no history of concussion. CONCLUSIONS The results suggest that there is no measureable biomechanical vulnerability to head impact related to a history of concussions in this youth population. This may be a reflection of the long time between the previous concussion and the one reconstructed in the laboratory, where such a long period has been associated with recovery from injury.

Patch-augmented rotator cuff repair: influence of the patch fixation technique on primary biomechanical stability.

PubMed

Jung, Christian; Spreiter, Gregor; Audigé, Laurent; Ferguson, Stephen J; Flury, Matthias

2016-05-01

There is an ongoing debate about the potential of patch augmentation to improve biomechanical stability and healing associated with rotator cuff repair. The biomechanical properties of three different patch-augmented rotator cuff repair techniques were assessed in vitro and compared with a standard repair. Dermal collagen patch augmentation may increase the primary stability and strength of the repaired tendon in vitro, depending on the technique used for patch application. Forty cadaveric sheep shoulders with dissected infraspinatus tendons were randomized into four groups (n = 10/group) for tendon repair using a knotless double-row suture anchor technique. A xenologous dermal extracellular matrix patch was used for augmentation in the three test groups using an "integrated", "cover", or "hybrid" technique. Tendons were preconditioned, cyclically loaded from 10 to 30 N at 1 Hz, and then loaded monotonically to failure. Biomechanical properties and the mode of failure were evaluated. Patch augmentation significantly increased the maximum load at failure by 61 % in the "cover" technique test group (225.8 N) and 51 % in the "hybrid" technique test group (211.4 N) compared with the non-augmented control group (140.2 N) (P ≤ 0.015). For the test group with "integrated" patch augmentation, the load at failure was 28 % lower (101.6 N) compared with the control group (P = 0.043). There was no significant difference in initial and linear stiffness among the four experimental groups. The most common mode of failure was tendon pullout. No anchor dislocation, patch disruption or knot breakage was observed. Additional patch augmentation with a collagen patch influences the biomechanical properties of a rotator cuff repair in a cadaveric sheep model. Primary repair stability can be significantly improved depending on the augmentation technique.

Are Cranial Biomechanical Simulation Data Linked to Known Diets in Extant Taxa? A Method for Applying Diet-Biomechanics Linkage Models to Infer Feeding Capability of Extinct Species

PubMed Central

Tseng, Zhijie Jack; Flynn, John J.

2015-01-01

Performance of the masticatory system directly influences feeding and survival, so adaptive hypotheses often are proposed to explain craniodental evolution via functional morphology changes. However, the prevalence of “many-to-one” association of cranial forms and functions in vertebrates suggests a complex interplay of ecological and evolutionary histories, resulting in redundant morphology-diet linkages. Here we examine the link between cranial biomechanical properties for taxa with different dietary preferences in crown clade Carnivora, the most diverse clade of carnivorous mammals. We test whether hypercarnivores and generalists can be distinguished based on cranial mechanical simulation models, and how such diet-biomechanics linkages relate to morphology. Comparative finite element and geometric morphometrics analyses document that predicted bite force is positively allometric relative to skull strain energy; this is achieved in part by increased stiffness in larger skull models and shape changes that resist deformation and displacement. Size-standardized strain energy levels do not reflect feeding preferences; instead, caniform models have higher strain energy than feliform models. This caniform-feliform split is reinforced by a sensitivity analysis using published models for six additional taxa. Nevertheless, combined bite force-strain energy curves distinguish hypercarnivorous versus generalist feeders. These findings indicate that the link between cranial biomechanical properties and carnivoran feeding preference can be clearly defined and characterized, despite phylogenetic and allometric effects. Application of this diet-biomechanics linkage model to an analysis of an extinct stem carnivoramorphan and an outgroup creodont species provides biomechanical evidence for the evolution of taxa into distinct hypercarnivorous and generalist feeding styles prior to the appearance of crown carnivoran clades with similar feeding preferences. PMID:25923776

Evaluating Glucocorticoid Administration on Biomechanical Properties of Rats’ Tibial Diaphysis

PubMed Central

Freidouni, Mohammadjavad; Nejati, Hossein; Salimi, Maryam; Bayat, Mohammad; Amini, Abdollah; Noruzian, Mohsen; Asgharie, Mohammad Ali; Rezaian, Milad

2015-01-01

Background: Osteoporosis is a disease, which causes bone loss and fractures. Although glucocorticoids effectively suppress inflammation, their chronic use is accompanied by bone loss with a tendency toward secondary osteoporosis. Objectives: This study took into consideration the importance of cortical bone in the entire bone's mechanical competence. Hence, the aim of this study was to assess the effects of different protocols of glucocorticoid administration on the biomechanical properties of tibial bone diaphysis in rats compared to control and low-level laser-treated rats. Materials and Methods: This experimental study was conducted at Shahid Beheshti University of Medical Sciences, Tehran, Iran. We used systematic random sampling to divide 40 adult male rats into 8 groups with 5 rats in each group. Groups were as follows: 1) control, 2) dexamethasone (7 mg/week), 3) dexamethasone (0.7 mg/week), 4) methylprednisolone (7 mg/kg/week), 5) methylprednisolone (5 mg/kg twice weekly), 6) dexamethasone (7 mg/kg three times per week), 7) dexamethasone (0.7 mg/kg thrice per week), and 8) low-level laser-treated rats. The study periods were 4-7 weeks. At the end of the treatment periods, we examined the mechanical properties of tibial bone diaphysis. Data were analyzed by statistical analyses. Results: Glucocorticoid-treated rats showed weight loss and considerable mortality (21%). The biomechanical properties (maximum force) of glucocorticoid-treated rats in groups 4 (62 ± 2.9), 6 (63 ± 5.1), and 7 (60 ± 5.3) were comparable with the control (46 ± 1.5) and low-level laser-treated (57 ± 3.2) rats. Conclusions: In contrast to the findings in humans and certain other species, glucocorticoid administration caused anabolic effect on the cortical bone of tibia diaphysis bone in rats. PMID:26019900

Computer simulation of stair falls to investigate scenarios in child abuse.

PubMed

Bertocci, G E; Pierce, M C; Deemer, E; Aguel, F

2001-09-01

To demonstrate the usefulness of computer simulation techniques in the investigation of pediatric stair falls. Since stair falls are a common falsely reported injury scenario in child abuse, our specific aim was to investigate the influence of stair characteristics on injury biomechanics of pediatric stair falls by using a computer simulation model. Our long-term goal is to use knowledge of biomechanics to aid in distinguishing between accidents and abuse. A computer simulation model of a 3-year-old child falling down stairs was developed using commercially available simulation software. This model was used to investigate the influence that stair characteristics have on biomechanical measures associated with injury risk. Since femur fractures occur in unintentional and abuse scenarios, biomechanical measures were focused on the lower extremities. The number and slope of steps and stair surface friction and elasticity were found to affect biomechanical measures associated with injury risk. Computer simulation techniques are useful for investigating the biomechanics of stair falls. Using our simulation model, we determined that stair characteristics have an effect on potential for lower extremity injuries. Although absolute values of biomechanical measures should not be relied on in an unvalidated model such as this, relationships between accident-environment factors and biomechanical measures can be studied through simulation. Future efforts will focus on model validation.

Comparison of 2 kinds of pedicle screws in primary spinal instrumentation: biomechanical and interfacial evaluations in sheep vertebrae in vitro.

PubMed

Liu, Da; Zhang, Yi; Lei, Wei; Wang, Cai-ru; Xie, Qing-yun; Liao, Dong-fa; Jiang, Kai; Zhou, Jin-song; Zhang, Bo; Pan, Xian-ming

2014-04-01

Expansive pedicle screw (EPS) and polymethylmethacrylate-augmented pedicle screw (PMMA-PS) were inserted in sheep vertebrae in vitro and were evaluated by performing biomechanical tests, radiographic examinations and histological observations. The objective of the study was to compare the biomechanical and interfacial performances of EPS and PMMA-PS in sheep lumbar vertebrae in vitro. It is a great challenge for orthopedic surgeons performing transpedicular fixation in the osteoporotic spine. It was reported that either the EPS or PMMA-PS could increase the screw stability. However, there are no studies comparing the 2 kinds of screws especially in primary spinal instrumentation. A total of 60 sheep lumbar vertebrae were randomly divided into 3 groups. A pilot hole was made in advance in all samples using the same method. Thereafter, the conventional pedicle screw (CPS) was inserted directly into the pilot hole in the CPS group; the hole in PMMA-PS group was first filled with polymethylmethacrylate (PMMA; 1.0 mL) and then inserted with CPS; and the EPS was inserted directly into the vertebrae in EPS group. After a period of 24 hours, biomechanical tests were performed to evaluate screw stability, and x-ray examination, micro-computerized tomography analysis, and histologic observation were performed to evaluate the interface between screw and bone. Compared with the stability of CPS, those of EPS and PMMA-PS were significantly enhanced. However, no significant differences were detected between the stabilities of EPS and PMMA-PS. The PMMA surrounding the screw blocked direct contact between bone and screw and formed a "screw-PMMA-bone" interface in the PMMA-PS group. There was a "screw-bone" interface in both CPS and EPS groups. Nevertheless, the expanded anterior part of EPS formed a claw-like structure pressing the surrounding bone trabeculae, which made the local bone tissue more compacted and denser than that in the CPS group. EPS can enhance the screw stability as markedly as the traditional PMMA-PS in primary surgery, and EPS can form a better immediate interface between screw and bone compared with PMMA-PS. EPS also can effectively avoid thermal injury, leakage, and compression caused by PMMA. A great feasibility was proved in this study to perform comparisons between the 2 kinds of pedicle screws in osteoporotic sheep vertebrae in vivo in the further research. In conclusion, we propose that EPS has a great application potential in augmentation of screw stability in the clinic.

Disc replacement adjacent to cervical fusion: a biomechanical comparison of hybrid construct versus two-level fusion.

PubMed

Lee, Michael J; Dumonski, Mark; Phillips, Frank M; Voronov, Leonard I; Renner, Susan M; Carandang, Gerard; Havey, Robert M; Patwardhan, Avinash G

2011-11-01

A cadaveric biomechanical study. To investigate the biomechanical behavior of the cervical spine after cervical total disc replacement (TDR) adjacent to a fusion as compared to a two-level fusion. There are concerns regarding the biomechanical effects of cervical fusion on the mobile motion segments. Although previous biomechanical studies have demonstrated that cervical disc replacement normalizes adjacent segment motion, there is a little information regarding the function of a cervical disc replacement adjacent to an anterior cervical decompression and fusion, a potentially common clinical application. Nine cadaveric cervical spines (C3-T1, age: 60.2 ± 3.5 years) were tested under load- and displacement-control testing. After intact testing, a simulated fusion was performed at C4-C5, followed by C6-C7. The simulated fusion was then reversed, and the response of TDR at C5-C6 was measured. A hybrid construct was then tested with the TDR either below or above a single-level fusion and contrasted with a simulated two-level fusion (C4-C6 and C5-C7). The external fixator device used to simulate fusion significantly reduced range of motion (ROM) at C4-C5 and C6-C7 by 74.7 ± 8.1% and 78.1 ± 11.5%, respectively (P < 0.05). Removal of the fusion construct restored the motion response of the spinal segments to their intact state. Arthroplasty performed at C5-C6 using the porous-coated motion disc prosthesis maintained the total flexion-extension ROM to the level of the intact controls when used as a stand-alone procedure or when implanted adjacent to a single-level fusion (P > 0.05). The location of the single-level fusion, whether above or below the arthroplasty, did not significantly affect the motion response of the arthroplasty in the hybrid construct. Performing a two-level fusion significantly increased the motion demands on the nonoperated segments as compared to a hybrid TDR-plus fusion construct when the spine was required to reach the same motion end points. The spine with a hybrid construct required significantly less extension moment than the spine with a two-level fusion to reach the same extension end point. The porous-coated motion cervical prosthesis restored the ROM of the treated level to the intact state. When the porous-coated motion prosthesis was used in a hybrid construct, the TDR response was not adversely affected. A hybrid construct seems to offer significant biomechanical advantages over two-level fusion in terms of reducing compensatory adjacent-level hypermobility and also loads required to achieve a predetermined ROM.

A hybrid patient-specific biomechanical model based image registration method for the motion estimation of lungs.

PubMed

Han, Lianghao; Dong, Hua; McClelland, Jamie R; Han, Liangxiu; Hawkes, David J; Barratt, Dean C

2017-07-01

This paper presents a new hybrid biomechanical model-based non-rigid image registration method for lung motion estimation. In the proposed method, a patient-specific biomechanical modelling process captures major physically realistic deformations with explicit physical modelling of sliding motion, whilst a subsequent non-rigid image registration process compensates for small residuals. The proposed algorithm was evaluated with 10 4D CT datasets of lung cancer patients. The target registration error (TRE), defined as the Euclidean distance of landmark pairs, was significantly lower with the proposed method (TRE = 1.37 mm) than with biomechanical modelling (TRE = 3.81 mm) and intensity-based image registration without specific considerations for sliding motion (TRE = 4.57 mm). The proposed method achieved a comparable accuracy as several recently developed intensity-based registration algorithms with sliding handling on the same datasets. A detailed comparison on the distributions of TREs with three non-rigid intensity-based algorithms showed that the proposed method performed especially well on estimating the displacement field of lung surface regions (mean TRE = 1.33 mm, maximum TRE = 5.3 mm). The effects of biomechanical model parameters (such as Poisson's ratio, friction and tissue heterogeneity) on displacement estimation were investigated. The potential of the algorithm in optimising biomechanical models of lungs through analysing the pattern of displacement compensation from the image registration process has also been demonstrated. Copyright © 2017 Elsevier B.V. All rights reserved.

Mechanical properties of canine osteosarcoma-affected antebrachia.

PubMed

Steffey, Michele A; Garcia, Tanya C; Daniel, Leticia; Zwingenberger, Allison L; Stover, Susan M

2017-05-01

To determine the influence of neoplasia on the biomechanical properties of canine antebrachia. Ex vivo biomechanical study. Osteosarcoma (OSA)-affected canine antebrachia (n = 12) and unaffected canine antebrachia (n = 9). Antebrachia were compressed in axial loading until failure. A load-deformation curve was used to acquire the structural mechanical properties of neoplastic and unaffected specimens. Structural properties and properties normalized by body weight (BW) and radius length were compared using analysis of variance (ANOVA). Modes of failure were compared descriptively. Neoplastic antebrachia fractured at, or adjacent to, the OSA in the distal radial diaphysis. Unaffected antebrachia failed via mid-diaphyseal radial fractures with a transverse cranial component and an oblique caudal component. Structural mechanical properties were more variable in neoplastic antebrachia than unaffected antebrachia, which was partially attributable to differences in bone geometry related to dog size. When normalized by dog BW and radial length, strength, stiffness, and energy to yield and failure, were lower in neoplastic antebrachia than in unaffected antebrachia. OSA of the distal radial metaphysis in dogs presented for limb amputation markedly compromises the structural integrity of affected antebrachia. However, biomechanical properties of affected bones was sufficient for weight-bearing, as none of the neoplastic antebrachia fractured before amputation. The behavior of tumor invaded bone under cyclic loading warrants further investigations to evaluate the viability of in situ therapies for bone tumors in dogs. © 2017 The American College of Veterinary Surgeons.

Diagnostic Assessment of Preparedness of Level One Sports Science Students for Biomechanics Modules

ERIC Educational Resources Information Center

Dixon, Sharon J.

2005-01-01

The primary objective of this study was to investigate the use of a diagnostic test to assess the preparedness of level one students for a sports biomechanics module. During their first week at university, a cohort of 108 students completed a diagnostic test at the end of their first lecture in sports biomechanics, with no prior notice. Upon…

"Proprietary Processed" Allografts: Clinical Outcomes and Biomechanical Properties in Anterior Cruciate Ligament Reconstruction.

PubMed

Roberson, Troy A; Abildgaard, Jeffrey T; Wyland, Douglas J; Siffri, Paul C; Geary, Stephen P; Hawkins, Richard J; Tokish, John M

2017-11-01

The processing of allograft tissues in anterior cruciate ligament (ACL) reconstruction continues to be controversial. While high-dose irradiation of grafts has received scrutiny for high failure rates, lower dose irradiation and "proprietary-based" nonirradiated sterilization techniques have become increasingly popular, with little in the literature to evaluate their outcomes. Recent studies have suggested that the specifics of allograft processing techniques may be a risk factor for higher failure rates. To assess these proprietary processes and their clinical outcomes and biomechanical properties. Systematic review. A systematic review was performed using searches of PubMed, EMBASE, Google Scholar, and Cochrane databases. English-language studies were identified with the following search terms: "allograft ACL reconstruction" (title/abstract), "novel allograft processing" (title/abstract), "allograft anterior cruciate ligament" (title/abstract), "anterior cruciate ligament allograft processing" (title/abstract), or "biomechanical properties anterior cruciate ligament allograft" (title/abstract). Duplicate studies, studies not providing the allograft processing technique, and those not containing the outcomes of interest were excluded. Outcomes of interest included outcome scores, complication and failure rates, and biomechanical properties of the processed allografts. Twenty-four studies (13 clinical, 11 biomechanical) met inclusion criteria for review. No demonstrable difference in patient-reported outcomes was appreciated between the processing techniques, with the exception of the Tutoplast process. The clinical failure rate of the Tutoplast process was unacceptably high (45% at 6 years), but no other difference was found between other processing techniques (BioCleanse: 5.4%; AlloTrue: 5.7%; MTF: 6.7%). Several studies did show an increased failure rate, but these studies either combined processing techniques or failed to delineate enough detail to allow a specific comparison for this study. The biomechanical studies showed overall maintenance of satisfactory biomechanical properties throughout multiple testing modes with normalization to the percentage of control specimens. A comparison of proprietary allograft processing techniques is difficult because of the variability and lack of specificity of reporting in the current literature. Among the available literature, except for the Tutoplast process, no notable differences were found in the clinical outcomes or biomechanical properties. Future study with a longer follow-up is necessary to determine the role and limitations of these grafts in the clinical setting.

[The use of open source software in graphic anatomic reconstructions and in biomechanic simulations].

PubMed

Ciobanu, O

2009-01-01

The objective of this study was to obtain three-dimensional (3D) images and to perform biomechanical simulations starting from DICOM images obtained by computed tomography (CT). Open source software were used to prepare digitized 2D images of tissue sections and to create 3D reconstruction from the segmented structures. Finally, 3D images were used in open source software in order to perform biomechanic simulations. This study demonstrates the applicability and feasibility of open source software developed in our days for the 3D reconstruction and biomechanic simulation. The use of open source software may improve the efficiency of investments in imaging technologies and in CAD/CAM technologies for implants and prosthesis fabrication which need expensive specialized software.

Change-of-Direction Biomechanics: Is What's Best for Anterior Cruciate Ligament Injury Prevention Also Best for Performance?

PubMed

Fox, Aaron S

2018-05-02

Change-of-direction maneuvers (e.g., side-step cutting) are an important aspect of performance in multi-directional sports, but these maneuvers are also associated with anterior cruciate ligament (ACL) injury. Despite this, the impact of biomechanics on ACL injury risk and performance is often examined in isolation. The purpose of this review was to examine the alignment between biomechanical recommendations for ACL injury prevention and performance with regard to change-of-direction maneuvers. Several studies linking change-of-direction biomechanics to both ACL injury risk and performance were examined. A degree of overlap was identified between biomechanical strategies that could both reduce ACL injury risk and enhance performance during change-of-direction maneuvers. A fore-foot footfall pattern along with trunk rotation and lateral flexion in the intended cutting direction were identified as biomechanical strategies that could both reduce potentially hazardous knee joint moments and enhance change-of-direction speed. Minimizing knee valgus during change-of-direction maneuvers may also reduce ACL injury risk, with this biomechanical strategy found to have no impact on performance. Certain biomechanical strategies proposed to reduce ACL injury risk were linked to reduced change-of-direction performance. A narrow foot placement and "soft" landings with greater knee flexion were identified as ACL injury prevention strategies that could have a negative impact on performance. The findings of this review emphasize the need to consider both ACL injury risk and performance when examining the biomechanics of change-of-direction maneuvers.

Influence of maturation on instep kick biomechanics in female soccer athletes.

PubMed

Lyle, Mark A; Sigward, Susan M; Tsai, Liang-Ching; Pollard, Christine D; Powers, Christopher M

2011-10-01

The purpose of this study was to compare kicking biomechanics between young female soccer players at two different stages of physical maturation and to identify biomechanical predictors of peak foot velocity. Swing and stance limb kinematics and kinetics were recorded from 20 female soccer players (10 prepubertal, 10 postpubertal) while kicking a soccer ball using an angled two-step approach. Peak foot velocity as well as hip and knee kinematics and kinetics were compared between groups using independent-samples t-tests. Pearson correlation coefficients and stepwise multiple regression were used to identify predictors of peak foot velocity. Peak foot velocity and the peak swing limb net hip flexor moment was significantly greater in the postpubertal group when compared with the prepubertal group (13.4 vs 11.6 m·s(-1), P = 0.003; 1.22 vs 1.07 N·m·kg(-1)·m(-1), P = 0.03). Peak stance limb hip and knee extensor moments were not different between groups. Although the peak swing limb hip and knee flexion angles were similar between groups, the postpubertal group demonstrated significantly less peak stance limb hip and knee flexion angles when compared with the prepubertal group (P < 0.001 and P = 0.045). Using a linear regression model, swing limb peak hip flexor moment and peak swing limb hip extension range of motion combined to explain 65% of the variance in peak foot velocity. Despite a difference in stance limb kinematics, similar swing limb kinematics between groups indicates that the prepubertal female athletes kicked with a mature swing limb kick pattern. The ability to generate a large hip flexor moment of the swing limb seems to be an important factor for improving kicking performance in young female soccer players.

Biomechanics of ramp descent in unilateral trans-tibial amputees: Comparison of a microprocessor controlled foot with conventional ankle-foot mechanisms.

PubMed

Struchkov, Vasily; Buckley, John G

2016-02-01

Walking down slopes and/or over uneven terrain is problematic for unilateral trans-tibial amputees. Accordingly, 'ankle' devices have been added to some dynamic-response feet. This study determined whether use of a microprocessor controlled passive-articulating hydraulic ankle-foot device improved the gait biomechanics of ramp descent in comparison to conventional ankle-foot mechanisms. Nine active unilateral trans-tibial amputees repeatedly walked down a 5° ramp, using a hydraulic ankle-foot with microprocessor active or inactive or using a comparable foot with rubber ball-joint (elastic) 'ankle' device. When inactive the hydraulic unit's resistances were those deemed to be optimum for level-ground walking, and when active, the plantar- and dorsi-flexion resistances switched to a ramp-descent mode. Residual limb kinematics, joints moments/powers and prosthetic foot power absorption/return were compared across ankle types using ANOVA. Foot-flat was attained fastest with the elastic foot and second fastest with the active hydraulic foot (P<0.001). Prosthetic shank single-support mean rotation velocity (p =0.006), and the flexion (P<0.001) and negative work done at the residual knee (P=0.08) were reduced, and negative work done by the ankle-foot increased (P<0.001) when using the active hydraulic compared to the other two ankle types. The greater negative 'ankle' work done when using the active hydraulic compared to other two ankle types, explains why there was a corresponding reduction in flexion and negative work at the residual knee. These findings suggest that use of a microprocessor controlled hydraulic foot will reduce the biomechanical compensations used to walk down slopes. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Biomechanical and histologic evaluation of two application forms of surgical glue for mesh fixation to the abdominal wall.

PubMed

Ortillés, Á; Pascual, G; Peña, E; Rodríguez, M; Pérez-Köhler, B; Mesa-Ciller, C; Calvo, B; Bellón, J M

2017-11-01

The use of an adhesive for mesh fixation in hernia repair reduces chronic pain and minimizes tissue damage in the patient. This study was designed to assess the adhesive properties of a medium-chain (n-butyl) cyanoacrylate glue applied as drops or as a spray in a biomechanical and histologic study. Both forms of glue application were compared to the use of simple-loose or continuous-running polypropylene sutures for mesh fixation. Eighteen adult New Zealand White rabbits were used. For mechanical tests in an ex vivo and in vivo study, patches of polypropylene mesh were fixed to an excised fragment of healthy abdominal tissue or used to repair a partial abdominal wall defect in the rabbit respectively. Depending on the fixation method used, four groups of 12 implants each or 10 implants each respectively for the ex vivo and in vivo studies were established: Glue-Drops, Glue-Spray, Suture-Simple and Suture-Continuous. Biomechanical resistance in the ex vivo implants was tested five minutes after mesh fixation. In vivo implants for biomechanical and histologic assessment were collected at 14 days postimplant. In the ex vivo study, the continuous suture implants showed the highest failure sample tension, while the implants fixed with glue showed lower failure sample tension values. However, the simple and continuous suture implants returned the highest stretch values. In the in vivo implants, failure sample tension values were similar among groups while the implants fixed with a continuous running suture had the higher stretch values, and the glue-fixed implants the lower stretch values. All meshes showed good tissue integration within the host tissue regardless of the fixation method used. Our histologic study revealed the generation of a denser, more mature repair tissue when the cyanoacrylate glue was applied as a spray rather than as drops. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of TRAIL gene on biomechanical properties of the human leukemic cell line Jurkat.

PubMed

Yao, Weijuan; Chen, Kai; Wang, Xinjuan; Xie, Lide; Wen, Zongyao; Yan, Zongyi; Chien, Shu

2002-12-01

We cloned the cDNA fragment of human TNF-related apoptosis inducing ligand (TRAIL) into RevTet-On, a Tet-regulated and high-level gene expression system. Making use of the TRAIL gene expression system in Jurkat as a cell model, we studied the influence of TRAIL gene on the biomechanics properties of Jurkat through measuring changes of cellular biomechanics properties before and after the TRAIL gene expression, which was induced by adding tetracycline derivative doxycycline (Dox). The results indicated that the TRAIL gene expression led to significant changes in cellular biomechanics properties. The osmotic fragility increased and the cell stiffness increased after the expression of TRAIL gene. Thus, the apoptosis-inducing TRAIL gene caused significant changes in the biomechanics properties of Jurkat cells.

Verification, Validation and Sensitivity Studies in Computational Biomechanics

PubMed Central

Anderson, Andrew E.; Ellis, Benjamin J.; Weiss, Jeffrey A.

2012-01-01

Computational techniques and software for the analysis of problems in mechanics have naturally moved from their origins in the traditional engineering disciplines to the study of cell, tissue and organ biomechanics. Increasingly complex models have been developed to describe and predict the mechanical behavior of such biological systems. While the availability of advanced computational tools has led to exciting research advances in the field, the utility of these models is often the subject of criticism due to inadequate model verification and validation. The objective of this review is to present the concepts of verification, validation and sensitivity studies with regard to the construction, analysis and interpretation of models in computational biomechanics. Specific examples from the field are discussed. It is hoped that this review will serve as a guide to the use of verification and validation principles in the field of computational biomechanics, thereby improving the peer acceptance of studies that use computational modeling techniques. PMID:17558646

The Quantal Larynx: The Stable Regions of Laryngeal Biomechanics and Implications for Speech Production.

PubMed

Moisik, Scott Reid; Gick, Bryan

2017-03-01

Recent proposals suggest that (a) the high dimensionality of speech motor control may be reduced via modular neuromuscular organization that takes advantage of intrinsic biomechanical regions of stability and (b) computational modeling provides a means to study whether and how such modularization works. In this study, the focus is on the larynx, a structure that is fundamental to speech production because of its role in phonation and numerous articulatory functions. A 3-dimensional model of the larynx was created using the ArtiSynth platform (http://www.artisynth.org). This model was used to simulate laryngeal articulatory states, including inspiration, glottal fricative, modal prephonation, plain glottal stop, vocal-ventricular stop, and aryepiglotto-epiglottal stop and fricative. Speech-relevant laryngeal biomechanics is rich with "quantal" or highly stable regions within muscle activation space. Quantal laryngeal biomechanics complement a modular view of speech control and have implications for the articulatory-biomechanical grounding of numerous phonetic and phonological phenomena.

Biomechanics as a window into the neural control of movement

PubMed Central

2016-01-01

Abstract Biomechanics and motor control are discussed as parts of a more general science, physics of living systems. Major problems of biomechanics deal with exact definition of variables and their experimental measurement. In motor control, major problems are associated with formulating currently unknown laws of nature specific for movements by biological objects. Mechanics-based hypotheses in motor control, such as those originating from notions of a generalized motor program and internal models, are non-physical. The famous problem of motor redundancy is wrongly formulated; it has to be replaced by the principle of abundance, which does not pose computational problems for the central nervous system. Biomechanical methods play a central role in motor control studies. This is illustrated with studies with the reconstruction of hypothetical control variables and those exploring motor synergies within the framework of the uncontrolled manifold hypothesis. Biomechanics and motor control have to merge into physics of living systems, and the earlier this process starts the better. PMID:28149390

Fibrin-Genipin Adhesive Hydrogel for Annulus Fibrosus Repair: Performance Evaluation with Large Animal Organ Culture, In Situ Biomechanics, and In Vivo Degradation Tests

PubMed Central

Likhitpanichkul, M.; Dreischarf, M.; Illien-Junger, S.; Walter, B. A.; Nukaga, T.; Long, R. G; Sakai, D.; Hecht, A. C.; Iatridis, J. C.

2015-01-01

Annulus fibrosus (AF) defects from annular tears, herniation, and discectomy procedures are associated with painful conditions and accelerated intervertebral disc (IVD) degeneration. Currently, no effective treatments exist to repair AF damage, restore IVD biomechanics and promote tissue regeneration. An injectable fibrin-genipin adhesive hydrogel (Fib-Gen) was evaluated for its performance repairing large AF defects in a bovine caudal IVD model using ex vivo organ culture and biomechanical testing of motion segments, and for its in vivo longevity and biocompatibility in a rat model by subcutaneous implantation. Fib-Gen sealed AF defects, prevented IVD height loss, and remained well-integrated with native AF tissue following approximately 14,000 cycles of compression in 6-day organ culture experiments. Fib-Gen repair also retained high viability of native AF cells near the repair site, reduced nitric oxide released to the media, and showed evidence of AF cell migration into the gel. Biomechanically, Fib-Gen fully restored compressive stiffness to intact levels validating organ culture findings. However, only partial restoration of tensile and torsional stiffness was obtained, suggesting opportunities to enhance this formulation. Subcutaneous implantation results, when compared with the literature, suggested Fib-Gen exhibited similar biocompatibility behaviour to fibrin alone but degraded much more slowly. We conclude that injectable Fib-Gen successfully sealed large AF defects, promoted functional restoration with improved motion segment biomechanics, and served as a biocompatible adhesive biomaterial that had greatly enhanced in vivo longevity compared to fibrin. Fib-Gen offers promise for AF repairs that may prevent painful conditions and accelerated degeneration of the IVD, and warrants further material development and evaluation. PMID:25036053

Fibrin-genipin adhesive hydrogel for annulus fibrosus repair: performance evaluation with large animal organ culture, in situ biomechanics, and in vivo degradation tests.

PubMed

Likhitpanichkul, M; Dreischarf, M; Illien-Junger, S; Walter, B A; Nukaga, T; Long, R G; Sakai, D; Hecht, A C; Iatridis, J C

2014-07-18

Annulus fibrosus (AF) defects from annular tears, herniation, and discectomy procedures are associated with painful conditions and accelerated intervertebral disc (IVD) degeneration. Currently, no effective treatments exist to repair AF damage, restore IVD biomechanics and promote tissue regeneration. An injectable fibrin-genipin adhesive hydrogel (Fib-Gen) was evaluated for its performance repairing large AF defects in a bovine caudal IVD model using ex vivo organ culture and biomechanical testing of motion segments, and for its in vivo longevity and biocompatibility in a rat model by subcutaneous implantation. Fib-Gen sealed AF defects, prevented IVD height loss, and remained well-integrated with native AF tissue following approximately 14,000 cycles of compression in 6-day organ culture experiments. Fib-Gen repair also retained high viability of native AF cells near the repair site, reduced nitric oxide released to the media, and showed evidence of AF cell migration into the gel. Biomechanically, Fib-Gen fully restored compressive stiffness to intact levels validating organ culture findings. However, only partial restoration of tensile and torsional stiffness was obtained, suggesting opportunities to enhance this formulation. Subcutaneous implantation results, when compared with the literature, suggested Fib-Gen exhibited similar biocompatibility behaviour to fibrin alone but degraded much more slowly. We conclude that injectable Fib-Gen successfully sealed large AF defects, promoted functional restoration with improved motion segment biomechanics, and served as a biocompatible adhesive biomaterial that had greatly enhanced in vivo longevity compared to fibrin. Fib-Gen offers promise for AF repairs that may prevent painful conditions and accelerated degeneration of the IVD, and warrants further material development and evaluation.

Role of biomechanics in the understanding of normal, injured, and healing ligaments and tendons

PubMed Central

Jung, Ho-Joong; Fisher, Matthew B; Woo, Savio L-Y

2009-01-01

Ligaments and tendons are soft connective tissues which serve essential roles for biomechanical function of the musculoskeletal system by stabilizing and guiding the motion of diarthrodial joints. Nevertheless, these tissues are frequently injured due to repetition and overuse as well as quick cutting motions that involve acceleration and deceleration. These injuries often upset this balance between mobility and stability of the joint which causes damage to other soft tissues manifested as pain and other morbidity, such as osteoarthritis. The healing of ligament and tendon injuries varies from tissue to tissue. Tendinopathies are ubiquitous and can take up to 12 months for the pain to subside before one could return to normal activity. A ruptured medial collateral ligament (MCL) can generally heal spontaneously; however, its remodeling process takes years and its biomechanical properties remain inferior when compared to the normal MCL. It is also known that a midsubstance anterior cruciate ligament (ACL) tear has limited healing capability, and reconstruction by soft tissue grafts has been regularly performed to regain knee function. However, long term follow-up studies have revealed that 20–25% of patients experience unsatisfactory results. Thus, a better understanding of the function of ligaments and tendons, together with knowledge on their healing potential, may help investigators to develop novel strategies to accelerate and improve the healing process of ligaments and tendons. With thousands of new papers published in the last ten years that involve biomechanics of ligaments and tendons, there is an increasing appreciation of this subject area. Such attention has positively impacted clinical practice. On the other hand, biomechanical data are complex in nature, and there is a danger of misinterpreting them. Thus, in these review, we will provide the readers with a brief overview of ligaments and tendons and refer them to appropriate methodologies used to obtain their biomechanical properties. Specifically, we hope the reader will pay attention to how the properties of these tissues can be altered due to various experimental and biologic factors. Following this background material, we will present how biomechanics can be applied to gain an understanding of the mechanisms as well as clinical management of various ligament and tendon ailments. To conclude, new technology, including imaging and robotics as well as functional tissue engineering, that could form novel treatment strategies to enhance healing of ligament and tendon are presented. PMID:19457264

The effect of combined photobiomodulation and metformin on open skin wound healing in a non-genetic model of type II diabetes.

PubMed

Asghari, Mohammadali; Kanonisabet, Ali; Safakhah, Mandanad; Azimzadeh, Zahra; Mostafavinia, Ataroalsadat; Taheri, Soudabeh; Amini, Abdollah; Ghorishi, Seyed Kamran; JalaliFiroozkohi, Reza; Bayat, Sahar; Bayat, Mohammad

2017-04-01

This study intended to examine the combined influences of photobiomodulation (PBM) and metformin on the microbial flora and biomechanical parameters of wounds in a non-genetic model of type II diabetes mellitus (TII DM). We induced a non-genetic model of TII DM in 20 rats by feeding them a 10% fructose solution for 2weeks followed by an injection of streptozotocin (STZ, 40mg/kg). After 21days from the injection of STZ, we induced one full-thickness skin wound in each of the diabetic rats. We randomly divided the rats into four groups: i) placebo; ii) pulsed wave laser (890nm, 80Hz, 0.324J/cm 2 ); iii) metformin; and iv) laser+metformin. Rats received daily intraperitoneal injections of metformin (50mg/kg). On days 7and 15 we inspected the microbial flora of each wound. On day 15 we obtained a standard sample from each healing wound for biomechanical analyses. PBM significantly decreased colony-forming units (CFUs) 7days after wound infliction compared to the placebo group (LSD test, p=0.012). Metformin significantly enhanced the biomechanical property (stress high load) of the wounds compared to the placebo group (LSD test, p=0.028). We observed the same significant result for PBM compared to the placebo group (LSD test, p=0.047). PBM significantly accelerated the wound healing process and significantly reduced CFUs of bacteria in a non-genetic rat model of TII DM. Copyright © 2017 Elsevier B.V. All rights reserved.

Biomechanical effects of sitting with adjustable ischial and lumbar support on occupational low back pain: evaluation of sitting load and back muscle activity

PubMed Central

Makhsous, Mohsen; Lin, Fang; Bankard, James; Hendrix, Ronald W; Hepler, Matthew; Press, Joel

2009-01-01

Background Compared to standing posture, sitting decreases lumbar lordosis, increases low back muscle activity, disc pressure, and pressure on the ischium, which are associated with occupational LBP. A sitting device that reduces spinal load and low back muscle activities may help increase sitting comfort and reduce LBP risk. The objective of this study is to investigate the biomechanical effect of sitting with a reduced ischial support and an enhanced lumbar support (Off-Loading) on load, interface pressure and muscle activities. Methods A laboratory test in low back pain (LBP) and asymptomatic subjects was designed to test the biomechanical effect of using the Off-Loading sitting posture. The load and interface pressure on seat and the backrest, and back muscle activities associated with usual and this Off-Loading posture were recorded and compared between the two postures. Results Compared with Normal (sitting upright with full support of the seat and flat backrest) posture, sitting in Off-Loading posture significantly shifted the center of the force and the peak pressure on the seat anteriorly towards the thighs. It also significantly decreased the contact area on the seat and increased that on the backrest. It decreased the lumbar muscle activities significantly. These effects are similar in individuals with and without LBP. Conclusion Sitting with reduced ischial support and enhanced lumbar support resulted in reduced sitting load on the lumbar spine and reduced the lumbar muscular activity, which may potentially reduce sitting-related LBP. PMID:19193245

SU-F-J-88: Comparison of Two Deformable Image Registration Algorithms for CT-To-CT Contour Propagation

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

Gopal, A; Xu, H; Chen, S

Purpose: To compare the contour propagation accuracy of two deformable image registration (DIR) algorithms in the Raystation treatment planning system – the “Hybrid” algorithm based on image intensities and anatomical information; and the “Biomechanical” algorithm based on linear anatomical elasticity and finite element modeling. Methods: Both DIR algorithms were used for CT-to-CT deformation for 20 lung radiation therapy patients that underwent treatment plan revisions. Deformation accuracy was evaluated using landmark tracking to measure the target registration error (TRE) and inverse consistency error (ICE). The deformed contours were also evaluated against physician drawn contours using Dice similarity coefficients (DSC). Contour propagationmore » was qualitatively assessed using a visual quality score assigned by physicians, and a refinement quality score (0 0.9 for lungs, > 0.85 for heart, > 0.8 for liver) and similar qualitative assessments (VQS < 0.35, RQS > 0.75 for lungs). When anatomical structures were used to control the deformation, the DSC improved more significantly for the biomechanical DIR compared to the hybrid DIR, while the VQS and RQS improved only for the controlling structures. However, while the inclusion of controlling structures improved the TRE for the hybrid DIR, it increased the TRE for the biomechanical DIR. Conclusion: The hybrid DIR was found to perform slightly better than the biomechanical DIR based on lower TRE while the DSC, VQS, and RQS studies yielded comparable results for both. The use of controlling structures showed considerable improvement in the hybrid DIR results and is recommended for clinical use in contour propagation.« less

Assessment of CD-ROM Technology in Classroom Teaching.

ERIC Educational Resources Information Center

Shellhart, W. Craig; Oesterle, Larry J.

1997-01-01

A study compared learning outcomes in an orthodontic biomechanics course when a CD-ROM was used in one group and photographic slides were used in another. Students in both groups performed at similar levels on a written examination and responded similarly to a statement reflecting how they understood the material. However, students felt the…

Femtosecond laser refractive surgery: small-incision lenticule extraction vs. femtosecond laser-assisted LASIK.

PubMed

Lee, Jimmy K; Chuck, Roy S; Park, Choul Yong

2015-07-01

Small-incision lenticule extraction (SMILE) is a novel technique devised to correct refractive errors. SMILE circumvents excimer laser photoablation of cornea, as the stromal lenticule cut by femtosecond laser is removed manually. Smaller incisions and preservation of anterior corneal biomechanical strength have been suggested as some of the advantages of SMILE over femtosecond laser-assisted LASIK (FS-LASIK). In this review, we compared previous published results of SMILE and FS-LASIK. The advantage, efficacy and safety of SMILE are compared with FS-LASIK. SMILE achieved similar efficacy, predictability and safety as FS-LASIK. Greater preservations of corneal biomechanical strength and corneal nerves were observed in SMILE when compared with LASIK or PRK. Additionally, the incidence of postoperative dry eye syndrome was found to be less problematic in SMILE than in FS-LASIK. SMILE is a promising new surgery for refractive error correction. Prospective and retrospective studies of SMILE have shown that results of SMILE are similar to FS-LASIK. With advances in femtosecond laser technology, SMILE may gain greater acceptance in the future.

Metabolics of stair ascent with a powered transfemoral prosthesis.

PubMed

Ledoux, E D; Lawson, B E; Shultz, A H; Bartlett, H L; Goldfarb, M

2015-01-01

This paper evaluates the effectiveness of a powered knee and ankle prosthesis for stair ascent through a metabolic assessment comparing energy expenditure of a single transfemoral amputee subject while ascending stairs with the powered prosthesis relative to his passive daily use device, as well as comparing the kinematics and kinetics obtained with the passive prosthesis to healthy biomechanics. The subject wore a portable system that measured pulmonary gaseous exchange rates of oxygen and carbon dioxide while he ascended stairs with each of the prostheses in alternating tests. The results indicated that the amputee's energy expenditure decreased by 32 percent while climbing with the powered prosthesis as compared to his passive one, and the kinematics and kinetics achieved were representative of healthy biomechanics.

Translating ocular biomechanics into clinical practice: current state and future prospects.

PubMed

Girard, Michaël J A; Dupps, William J; Baskaran, Mani; Scarcelli, Giuliano; Yun, Seok H; Quigley, Harry A; Sigal, Ian A; Strouthidis, Nicholas G

2015-01-01

Biomechanics is the study of the relationship between forces and function in living organisms and is thought to play a critical role in a significant number of ophthalmic disorders. This is not surprising, as the eye is a pressure vessel that requires a delicate balance of forces to maintain its homeostasis. Over the past few decades, basic science research in ophthalmology mostly confirmed that ocular biomechanics could explain in part the mechanisms involved in almost all major ophthalmic disorders such as optic nerve head neuropathies, angle closure, ametropia, presbyopia, cataract, corneal pathologies, retinal detachment and macular degeneration. Translational biomechanics in ophthalmology, however, is still in its infancy. It is believed that its use could make significant advances in diagnosis and treatment. Several translational biomechanics strategies are already emerging, such as corneal stiffening for the treatment of keratoconus, and more are likely to follow. This review aims to cultivate the idea that biomechanics plays a major role in ophthalmology and that the clinical translation, lead by collaborative teams of clinicians and biomedical engineers, will benefit our patients. Specifically, recent advances and future prospects in corneal, iris, trabecular meshwork, crystalline lens, scleral and lamina cribrosa biomechanics are discussed.

Translating Ocular Biomechanics into Clinical Practice: Current State and Future Prospects

PubMed Central

Girard, Michaël J.A.; Dupps, William J.; Baskaran, Mani; Scarcelli, Giuliano; Yun, Seok H.; Quigley, Harry A.; Sigal, Ian A.; Strouthidis, Nicholas G.

2014-01-01

Biomechanics – the study of the relationship between forces and function in living organisms – is thought to play a critical role in a significant number of ophthalmic disorders. This is not surprising, as the eye is a pressure vessel that requires a delicate balance of forces to maintain its homeostasis. Over the past few decades, basic science research in ophthalmology mostly confirmed that ocular biomechanics could explain in part the mechanisms involved in almost all major ophthalmic disorders such as optic nerve head neuropathies, angle closure, ametropia, presbyopia, cataract, corneal pathologies, retinal detachment, and macular degeneration. Translational biomechanics in ophthalmology, however, is still in its infancy. It is believed that its use could make significant advances in diagnosis and treatment. Several translational biomechanics strategies are already emerging, such as corneal stiffening for the treatment of keratoconus, and more are likely to follow. This review aims to cultivate the idea that biomechanics plays a major role in ophthalmology and that its clinical translation, lead by collaborative teams of clinicians and biomedical engineers, will benefit our patients. Specifically, recent advances and future prospects in corneal, iris, trabecular meshwork, crystalline lens, scleral and lamina cribrosa biomechanics are discussed. PMID:24832392

Sport-specific biomechanical responses to an ACL injury prevention programme: A randomised controlled trial.

PubMed

Taylor, Jeffrey B; Ford, Kevin R; Schmitz, Randy J; Ross, Scott E; Ackerman, Terry A; Shultz, Sandra J

2018-04-19

Anterior cruciate ligament (ACL) injury prevention programmes have not been as successful at reducing injury rates in women's basketball as in soccer. This randomised controlled trial (ClinicalTrials.gov #NCT02530333) compared biomechanical adaptations in basketball and soccer players during jump-landing activities after an ACL injury prevention programme. Eighty-seven athletes were cluster randomised into intervention (6-week programme) and control groups. Three-dimensional biomechanical analyses of drop vertical jump (DVJ), double- (SAG-DL) and single-leg (SAG-SL) sagittal, and double- (FRONT-DL) and single-leg (FRONT-SL) frontal plane jump landing tasks were tested before and after the intervention. Peak angles, excursions, and joint moments were analysed using two-way MANCOVAs of post-test scores while controlling for pre-test scores. During SAG-SL the basketball intervention group exhibited increased peak knee abduction angles (p = .004) and excursions (p = .003) compared to the basketball control group (p = .01) and soccer intervention group (p = .01). During FRONT-SL, the basketball intervention group exhibited greater knee flexion excursion after training than the control group (p = .01), but not the soccer intervention group (p = .11). Although women's soccer players exhibit greater improvements in knee abduction kinematics than basketball players, these athletes largely exhibit similar biomechanical adaptations to ACL injury prevention programmes.

Kinematic and kinetic differences between left-and right-handed professional baseball pitchers.

PubMed

Diffendaffer, Alek Z; Fleisig, Glenn S; Ivey, Brett; Aune, Kyle T

2018-03-21

While 10% of the general population is left-handed, 27% of professional baseball pitchers are left-handed. Biomechanical differences between left- and right-handed college pitchers have been previously reported, but these differences have yet to be examined at the professional level. Therefore, the purpose of this study was to compare pitching biomechanics between left- and right-handed professional pitchers. It was hypothesised that there would be significant kinematic and kinetic differences between these two groups. Pitching biomechanics were collected on 96 left-handed pitchers and a group of 96 right-handed pitchers matched for age, height, mass and ball velocity. Student t-tests were used to identify kinematic and kinetic differences (p < 0.05). Of the 31 variables tested, only four were found to be significantly different between the groups. Landing position of the stride foot, trunk separation at foot contact, maximum shoulder external rotation and trunk forward tilt at ball release were all significantly greater in right-handed pitchers. The magnitude of the statistical differences found were small and not consistent with differences in the two previous, smaller studies. Thus, the differences found may be of minimal practical significance and mechanics can be taught the same to all pitchers, regardless of throwing hand.

Real-time biofeedback to target risk of anterior cruciate ligament injury: a technical report for injury prevention and rehabilitation.

PubMed

Ford, Kevin R; DiCesare, Christopher A; Myer, Gregory D; Hewett, Timothy E

2015-05-20

Biofeedback training enables an athlete to alter biomechanical and physiological function by receiving biomechanical and physiological data concurrent with or immediately after a task. To compare the effects of 2 different modes of real-time biofeedback focused on reducing risk factors related to anterior cruciate ligament injury. Randomized crossover study design. Biomechanics laboratory and sports medicine center. Female high school soccer players (age 14.8 ± 1.0 y, height 162.6 ± 6.8 cm, mass 55.9 ± 7.0 kg; n = 4). A battery of kinetic- or kinematic-based real-time biofeedback during repetitive double-leg squats. Baseline and posttraining drop vertical jumps were collected to determine if either feedback method improved high injury risk landing mechanics. Maximum knee abduction moment and angle during the landing was significantly decreased after kinetic-focused biofeedback (P = .04). The reduced knee abduction moment during the drop vertical jumps after kinematic-focused biofeedback was not different (P = .2). Maximum knee abduction angle was significantly decreased after kinetic biofeedback (P < .01) but only showed a trend toward reduction after kinematic biofeedback (P = .08). The innovative biofeedback employed in the current study reduced knee abduction load and posture from baseline to posttraining during a drop vertical jump.

Terrain stiffness and ankle biomechanics during simulated half-squat parachute landing.

PubMed

Niu, Wenxin; Fan, Yubo

2013-12-01

A hard surface is potentially one of the risk factors for ankle injuries during parachute landing, but this has never been experimentally validated. This study was designed to evaluate the effects of terrain stiffness on ankle biomechanics during half-squat parachute landing (HSPL). Eight male and eight female healthy participants landed on three surfaces with standard HSPL technique. The three surfaces were cushioned mats with different thicknesses (0 mm, 4 mm, and 8 mm). The effects of terrain hardness and gender and their interaction with ground reaction forces, ankle kinematics, and electromyograms of selected lower-extremity muscles were statistically analyzed with multivariate analysis of variance. The effects of terrain stiffness and the interaction between factors on all variables were not statistically significant. The effects of gender were not statistically significant on most variables. The peak angular velocity of the ankle dorsiflexion was significantly lower in men (mean 1345 degree x s(-1)) than in women (mean 1965 degree x s(-1)). A spongy surface even eliminated the differences between men compared to women in the activity of their tibialis anterior during simulated HSPL. Terrain stiffness, in the ranges tested, did not appear to influence ankle biomechanics among individuals performing HSPL. Additional studies are required to know whether this finding is applicable to realistic parachuting.

Nandrolone decanoate and load increase remodeling and strength in human supraspinatus bioartificial tendons.

PubMed

Triantafillopoulos, Ioannis K; Banes, Albert J; Bowman, Karl F; Maloney, Melissa; Garrett, William E; Karas, Spero G

2004-06-01

To date, no studies document the effect of anabolic steroids on rotator cuff tendons. Controlled laboratory study. Anabolic steroids enhance remodeling and improve the biomechanical properties of bioartificially engineered human supraspinatus tendons. Bioartificial tendons were treated with either nandrolone decanoate (nonload, steroid, n = 18), loading (load, nonsteroid, n = 18), or both (load, steroid, n = 18). A control group received no treatment (nonload, nonsteroid [NLNS], n = 18). Bioartificial tendons' remodeling was assessed by daily scanning, cytoskeletal organization by staining, matrix metalloproteinase-3 levels by ELISA assay, and biomechanical properties by load-to-failure testing. The load, steroid group showed the greatest remodeling and the best organized actin cytoskeleton. Matrix metallo-proteinase-3 levels in the load, steroid group were greater than those of the nonload, nonsteroid group (P <.05). Ultimate stress and ultimate strain in the load, steroid group were greater than those of the nonload, nonsteroid and nonload, steroid groups (P <.05). The strain energy density in the load, steroid group was greater when compared to other groups (P <.05). Nandrolone decanoate and load acted synergistically to increase matrix remodeling and biomechanical properties of bioartificial tendons. Data suggest anabolic steroids may enhance production of bioartificial tendons and rotator cuff tendon healing in vitro. More research is necessary before such clinical use is recommended.

Effect of Tendon Stem Cells in Chitosan/β-Glycerophosphate/Collagen Hydrogel on Achilles Tendon Healing in a Rat Model.

PubMed

Yang, Zhijin; Cao, Honghui; Gao, Shang; Yang, Mingyu; Lyu, Jingtong; Tang, Kanglai

2017-09-27

BACKGROUND The aim of this study was to determine whether the local application of tendon stem cells (TSCs) with chitosan/β-glycerophosphate/collagen(C/GP/Co) hydrogel promotes healing after an acute Achilles tendon injury in a rat model. MATERIAL AND METHODS Ninety-six Sprague-Dawley (SD) rats were used to make an Achilles tendon defect model, then the animals were randomly divided into 4 groups consisting of 8 rats each: control group, hydrogel group, TSCs group, and TSCs with hydrogel group. At 2, 4, and 6 weeks after treatment, tendon samples were harvested, and the quality of tendon repair was evaluated based on histology, immunohistochemistry, and biomechanical properties. RESULTS Combining TSCs with C/GP/Co hydrogel significantly enhances tendon healing compared with the control, hydrogel, and TSCs groups. The improved healing was indicated by the improvement in histological and immunohistochemistry outcomes and the increase in the biomechanical properties of the regenerated tissue at both 4 and 6 weeks post-injury. CONCLUSIONS This study demonstrates that the transplantation of TSCs combined with C/GP/Co hydrogel significantly improved the histological, immunohistochemistry, and biomechanical outcomes of the regenerated tissue at 4 and 6 weeks after implantation. TSCs with C/GP/Co hydrogel is a potentially effective treatment for tendon injury.

A non-invasive biomechanical device and treatment for patients following total hip arthroplasty: results of a 6-month pilot investigation

PubMed Central

2013-01-01

Background The purpose of the study was to examine the effect of a foot-worn biomechanical device on the clinical measurements and gait patterns of patients with total hip arthroplasty (THA). Methods Nineteen patients, up to 3 months post-THA, were enrolled to the study. Patients underwent a computerized gait analysis to calculate spatiotemporal parameters and completed the Western Ontario and McMaster Universities osteoarthritis index and the SF-36 health survey. Patients then began therapy with a non-invasive foot-worn biomechanical device coupled with a treatment methodology (AposTherapy). Patients received exercise guidelines and used the device daily during their regular activities at their own environment. Follow-up examinations were conducted after 4, 12, and 26 weeks of therapy. Repeated measures ANOVA was used to evaluate changes over time. The clinical significance of the treatment effect was evaluated by computing the Cohen's effect sizes (ES statistic). Results After 26 weeks of therapy, a significant improvement was seen in gait velocity (50.3%), involved step length (22.9%), and involved single limb support (16.5%). Additionally, a significant reduction in pain (85.4%) and improvement in function (81.1%) and quality of life (52.1%) were noted. Conclusions Patients following THA demonstrated a significant improvement in gait parameters and in self-assessment evaluations of pain, function, and quality of life. We recommend further RCTs to examine the effect of this therapy compared to other rehabilitation modalities following THA and compared to healthy matched controls. Trial registration Clinical trial registration number NCT01266382 PMID:23692690

Biomechanical investigation into the role of the periodontal ligament in optimising orthodontic force: a finite element case study.

PubMed

Liao, Zhipeng; Chen, Junning; Li, Wei; Darendeliler, M Ali; Swain, Michael; Li, Qing

2016-06-01

This paper aimed to precisely locate centres of resistance (CRe) of maxillary teeth and investigate optimal orthodontic force by identifying the effective zones of orthodontic tooth movement (OTM) from hydrostatic stress thresholds in the periodontal ligament (PDL). We applied distally-directed tipping and bodily forces ranging from 0.075 N to 3 N (7.5 g to 300 g) onto human maxillary teeth. The hydrostatic stress was quantified from nonlinear finite element analysis (FEA) and compared with normal capillary and systolic blood pressure for driving the tissue remodelling. Two biomechanical stimuli featuring localised and volume-averaged hydrostatic stresses were introduced to describe OTM. Locations of CRe were determined through iterative FEA simulation. Accurate locations of CRes of teeth and ranges of optimal orthodontic forces were obtained. By comparing with clinical results in literature, the volume average of hydrostatic stress in PDL was proved to describe the process of OTM more indicatively. The optimal orthodontic forces obtained from the in-silico modelling study echoed with the clinical results in vivo. A universal moment to force (M/F) ratio is not recommended due to the variation in patients and loading points. Accurate computational determination of CRe location can be applied in practice to facilitate orthodontic treatment. Global measurement of hydrostatic pressure in the PDL better characterised OTM, implying that OTM occurs only when the majority of PDL volume is critically stressed. The FEA results provide new insights into relevant orthodontic biomechanics and help establish optimal orthodontic force for a specific patient. Copyright © 2016 Elsevier Ltd. All rights reserved.

Low-Level Laser Therapy and Cryotherapy as Mono- and Adjunctive Therapies for Achilles Tendinopathy in Rats.

PubMed

Haslerud, Sturla; Lopes-Martins, Rodrigo Alvaro Brandão; Frigo, Lúcio; Bjordal, Jan Magnus; Marcos, Rodrigo Labat; Naterstad, Ingvill Fjell; Magnussen, Liv Heide; Joensen, Jon

2017-01-01

Low-level laser therapy (LLLT) and cryotherapy are widely used treatments in the acute phase of tendon injury. The aim of this study was to investigate the interaction of these two treatments on tendon inflammation and mechanical properties. Six groups of six Wistar rats were used in this study. The Achilles tendons of the healthy control group were not subjected to injury or treatment. The tendons of the injured nontreated group (ING) were injured, but not treated. The remaining four groups were injured and subjected to LLLT, cryotherapy, LLLT first/cryotherapy, or cryotherapy first/LLLT. All treatments were performed at 1 h post-trauma. Inflammatory mediators, tendon histology, and biomechanical properties were assessed at 24 h post-trauma by comparing the treatment groups with the ING. In all treatment groups, the inflammatory process shifted in an anti-inflammatory direction compared with the ING. Significant alterations in cytokine expression were found in only the LLLT group (↓IL-1β) and the combined intervention groups (↓IL-1β, ↓TNF-α, ↑IL-6). It was also found that cryotherapy followed by LLLT was the only treatment that significantly (p < 0.05) improved the biomechanical parameters of force (N) and displacement (mm) at the tendon rupture and corresponded with the best histological scores of all of the treatment groups. Our results demonstrate that cryotherapy in combination with LLLT can produce an anti-inflammatory "add-on" effect. The order of therapy administration seems essential, as superior histology and biomechanical results were found in the cryotherapy first/LLLT group.

Lateral clavicle fracture with coracoclavicular ligament injury: a biomechanical study of 4 different repair techniques.

PubMed

Alaee, Farhang; Apostolakos, John; Singh, Hardeep; Holwein, Christian; Diermeier, Theresa; Cote, Mark P; Beitzel, Knut; Imhoff, Andreas B; Mazzocca, Augustus D; Voss, Andreas

2017-07-01

To investigate the biomechanical performance of four different methods used for coracoclavicular (CC) ligament reconstruction in a lateral clavicle fracture repair. Native displacement, translation, and rotation at the acromioclavicular joint of 24 fresh-frozen cadaveric shoulders were tested. A reproducible fracture in the lateral third of the clavicle was created by dissecting both CC ligaments. Each specimen was then repaired with plate fixation of the fracture and the following CC repair technique: (1) Cortical button. (2) Suture anchor and plate button. (3) Suture anchor no plate button, and (4) Suture around coracoid. All reconstructed specimens were then re-tested for displacement, translation, and load to failure, and compared to their native results. Groups 1 and 3 were investigated for rotational load. There was no difference in load to failure between the repaired groups (p: ns). Group 1 showed less superior and anterior translations (p < 0.05). Group 2 showed significantly less superior translation (p = 0.003), but no significance with anterior and posterior translations to the native joint. Group 3 showed less superior and posterior translations (p = 0.005 and p = 0.039). Anterior and posterior translations were increased in group 4 (p < 0.05). The biomechanical analyses did not show any significance in load to failure or displacement after cyclic loading among the study groups. All repairs were effective in preventing superior translation. Groups 1 and 2 demonstrated increased horizontal stability compared to the native state. All 4 methods are clinically viable options for CC ligament repair.

The effects of shoe-worn insoles on gait biomechanics in people with knee osteoarthritis: a systematic review and meta-analysis.

PubMed

Shaw, Kathryn E; Charlton, Jesse M; Perry, Christina K L; de Vries, Courtney M; Redekopp, Matthew J; White, Jordan A; Hunt, Michael A

2018-02-01

The effect of shoe-worn insoles on biomechanical variables in people with medial knee osteoarthritis has been studied extensively. The majority of research has focused specifically on the effect of lateral wedge insoles at the knee. The aim of this systematic review and meta-analysis was to summarise the known effects of different shoe-worn insoles on all biomechanical variables during level walking in this patient population to date. Four electronic databases were searched to identify studies containing biomechanical data using shoe-worn insole devices in the knee osteoarthritis population. Methodological quality was assessed and a random effects meta-analysis was performed on biomechanical variables reported in three or more studies for each insole. Twenty-seven studies of moderate-to-high methodological quality were included in this review. The primary findings were consistent reductions in the knee adduction moment with lateral wedge insoles, although increases in ankle eversion with these insoles were also found. Lateral wedge insoles produce small reductions in knee adduction angles and external moments, and moderate increases in ankle eversion. The addition of an arch support to a lateral wedge minimises ankle eversion change, and also minimises adduction moment reductions. The paucity of available data on other insole types and other biomechanical outcomes presents an opportunity for future research. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Biomechanical study of different fixation techniques for the treatment of sacroiliac joint injuries using finite element analyses and biomechanical tests.

PubMed

Lee, Chian-Her; Hsu, Ching-Chi; Huang, Po-Yuang

2017-08-01

The pelvis is one of the most stressed areas of the human musculoskeletal system due to the transfer of truncal loads to the lower extremities. Sacroiliac joint injury may lead to abnormal joint mechanics and an unstable pelvis. Various fixation techniques have been evaluated and discussed. However, it may be difficult to investigate each technique due to variations in bone quality, bone anatomy, fracture pattern, and fixation location. Additionally, the finite element method is one useful technology that avoids these variations. Unfortunately, most previous studies neglected the effects of the lumbar spine and femurs when they investigated the biomechanics of pelvises. Thus, the aim of this study was to investigate the biomechanical performance of intact, injured, and treated pelvises using numerical and experimental approaches. Three-dimensional finite element models of the spine-pelvis-femur complex with and without muscles and ligaments were developed. The intact pelvis, the pelvis with sacroiliac joint injury, and three types of pelvic fixation techniques were analyzed. Concurrently, biomechanical tests were conducted to validate the numerical outcomes using artificial pelvises. Posterior iliosacral screw fixation showed relatively better fixation stability and lower risks of implant failure and pelvic breakage than sacral bar fixation and a locking compression plate fixation. The present study can help surgeons and engineers understand the biomechanics of intact, injured, and treated pelvises. Both the simulation technique and the experimental setup can be applied to investigate different pelvic injuries. Copyright © 2017 Elsevier Ltd. All rights reserved.

Topographic and biomechanical evaluation of cornea in patients with ichthyosis vulgaris.

PubMed

Kara, Necip; Yildirim, Yusuf; Demircan, Ali; Cankaya, Ilker; Kutlubay, Zekayi; Engin, Burhan; Serdaroglu, Server

2012-10-01

To compare the topographic and biomechanical properties of corneas in eyes of patients with ichthyosis vulgaris (IV) and eyes of healthy individuals. Thirty healthy individuals (control group) and 30 patients with IV (study group) were enrolled in this prospective study. Topographic measurements, including keratometry values, irregularity, and surface asymmetry index in the right eye of each participant were obtained using Scheimpflug camera with a Placido disc topographer (Sirius). Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc) and Goldman-related intraocular pressure (IOPg) were measured using the Reichert Ocular Response Analyzer (ORA). Central corneal thickness (CCT) was also measured with ultrasonic pachymetry and the Sirius corneal topography system. Topographic parameters were not significantly different between both groups (p>0.05). Although mean CH was not significantly different between the groups, the CRF was significantly lower in patients with IV (p=0.249 and p=0.005, respectively). The CCT was significantly lower in patients with IV compared to healthy controls (p<0.001). The IOPg and IOPcc were significantly lower in the patients with ichthyosis than in healthy controls (p=0.001 and p=0.004, respectively). The study demonstrated that while the eyes of patients with IV had corneal topographic findings and corneal hysteresis similar to those of healthy controls, some of corneal biomechanical properties such CRF and CCT and IOP values such as IOPg and IOPcc were significantly lower in patients with IV. These results should be taken into account when planning a corneal refractive surgery and glaucoma screening for patients with IV. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Biomechanical Comparison of Robotically Applied Pure Moment, Ideal Follower Load, and Novel Trunk Weight Loading Protocols on L4-L5 Cadaveric Segments during Flexion-Extension.

PubMed

Bennett, Charles R; DiAngelo, Denis J; Kelly, Brian P

2015-01-01

Extremely few in-vitro biomechanical studies have incorporated shear loads leaving a gap for investigation, especially when applied in combination with compression and bending under dynamic conditions. The objective of this study was to biomechanically compare sagittal plane application of two standard protocols, pure moment (PM) and follower load (FL), with a novel trunk weight (TW) loading protocol designed to induce shear in combination with compression and dynamic bending in a neutrally potted human cadaveric L4-L5 motion segment unit (MSU) model. A secondary objective and novelty of the current study was the application of all three protocols within the same testing system serving to reduce artifacts due to testing system variability. Six L4-L5 segments were tested in a Cartesian load controlled system in flexion-extension to 8Nm under PM, simulated ideal 400N FL, and vertically oriented 400N TW loading protocols. Comparison metrics used were rotational range of motion (RROM), flexibility, neutral zone (NZ) range of motion, and L4 vertebral body displacements. Significant differences in vertebral body translations were observed with different initial force applications but not with subsequent bending moment application. Significant reductions were observed in combined flexion-extension RROM, in flexibility during extension, and in NZ region flexibility with the TW loading protocol as compared to PM loading. Neutral zone ranges of motion were not different between all protocols. The combined compression and shear forces applied across the spinal joint in the trunk weight protocol may have a small but significantly increased stabilizing effect on segment flexibility and kinematics during sagittal plane flexion and extension.

Biomechanical Comparison of Robotically Applied Pure Moment, Ideal Follower Load, and Novel Trunk Weight Loading Protocols on L4-L5 Cadaveric Segments during Flexion-Extension

PubMed Central

Bennett, Charles R.; DiAngelo, Denis J.

2015-01-01

Background Extremely few in-vitro biomechanical studies have incorporated shear loads leaving a gap for investigation, especially when applied in combination with compression and bending under dynamic conditions. The objective of this study was to biomechanically compare sagittal plane application of two standard protocols, pure moment (PM) and follower load (FL), with a novel trunk weight (TW) loading protocol designed to induce shear in combination with compression and dynamic bending in a neutrally potted human cadaveric L4-L5 motion segment unit (MSU) model. A secondary objective and novelty of the current study was the application of all three protocols within the same testing system serving to reduce artifacts due to testing system variability. Methods Six L4-L5 segments were tested in a Cartesian load controlled system in flexion-extension to 8Nm under PM, simulated ideal 400N FL, and vertically oriented 400N TW loading protocols. Comparison metrics used were rotational range of motion (RROM), flexibility, neutral zone (NZ) range of motion, and L4 vertebral body displacements. Results Significant differences in vertebral body translations were observed with different initial force applications but not with subsequent bending moment application. Significant reductions were observed in combined flexion-extension RROM, in flexibility during extension, and in NZ region flexibility with the TW loading protocol as compared to PM loading. Neutral zone ranges of motion were not different between all protocols. Conclusions The combined compression and shear forces applied across the spinal joint in the trunk weight protocol may have a small but significantly increased stabilizing effect on segment flexibility and kinematics during sagittal plane flexion and extension. PMID:26273551

A three-year prospective comparative gait study between patients with ankle arthrodesis and arthroplasty.

PubMed

Segal, Ava D; Cyr, Krista M; Stender, Christina J; Whittaker, Eric C; Hahn, Michael E; Orendurff, Michael S; Ledoux, William R; Sangeorzan, Bruce J

2018-05-01

End-stage ankle arthritis is a debilitating condition that often requires surgical intervention after failed conservative treatments. Ankle arthrodesis is a common surgical option, especially for younger and highly active patients; however, ankle arthroplasty has become increasingly popular as advancements in implant design improve device longevity. The longitudinal differences in biomechanical outcomes between these surgical treatments remain indistinct, likely due to the challenges associated with objective study of a heterogeneous population. Patients scheduled for arthroplasty (n = 27) and arthrodesis (n = 20) were recruited to participate in this three-year prospective study. Postoperative functional outcomes were compared at distinct annual time increments using measures of gait analysis, average daily step count and survey score. Both surgical groups presented reduced pain, improved survey scores, and increased walking speed at the first-year postoperative session, which were generally consistent across the three-year follow-up. Arthrodesis patients walked with decreased sagittal ankle RoM, increased sagittal hip RoM, increased step length, and increased transient force at heel strike, postoperatively. Arthroplasty patients increased ankle RoM and cadence, with no changes in hip RoM, step length or heel strike transient force. Most postoperative changes were detected at the first-year follow-up session and maintained across the three-year time period. Despite generally favorable outcomes associated with both surgeries, several underlying postoperative biomechanical differences were detected, which may have long-term functional consequences. Furthermore, neither technique was able to completely restore gait biomechanics to the levels of the contralateral unaffected limb, leaving potential for the development of improved surgical and rehabilitative treatments. Published by Elsevier Ltd.

Biomechanical effects of hybrid stabilization on the risk of proximal adjacent-segment degeneration following lumbar spinal fusion using an interspinous device or a pedicle screw-based dynamic fixator.

PubMed

Lee, Chang-Hyun; Kim, Young Eun; Lee, Hak Joong; Kim, Dong Gyu; Kim, Chi Heon

2017-12-01

OBJECTIVE Pedicle screw-rod-based hybrid stabilization (PH) and interspinous device-based hybrid stabilization (IH) have been proposed to prevent adjacent-segment degeneration (ASD) and their effectiveness has been reported. However, a comparative study based on sound biomechanical proof has not yet been reported. The aim of this study was to compare the biomechanical effects of IH and PH on the transition and adjacent segments. METHODS A validated finite element model of the normal lumbosacral spine was used. Based on the normal model, a rigid fusion model was immobilized at the L4-5 level by a rigid fixator. The DIAM or NFlex model was added on the L3-4 segment of the fusion model to construct the IH and PH models, respectively. The developed models simulated 4 different loading directions using the hybrid loading protocol. RESULTS Compared with the intact case, fusion on L4-5 produced 18.8%, 9.3%, 11.7%, and 13.7% increments in motion at L3-4 under flexion, extension, lateral bending, and axial rotation, respectively. Additional instrumentation at L3-4 (transition segment) in hybrid models reduced motion changes at this level. The IH model showed 8.4%, -33.9%, 6.9%, and 2.0% change in motion at the segment, whereas the PH model showed -30.4%, -26.7%, -23.0%, and 12.9%. At L2-3 (adjacent segment), the PH model showed 14.3%, 3.4%, 15.0%, and 0.8% of motion increment compared with the motion in the IH model. Both hybrid models showed decreased intradiscal pressure (IDP) at the transition segment compared with the fusion model, but the pressure at L2-3 (adjacent segment) increased in all loading directions except under extension. CONCLUSIONS Both IH and PH models limited excessive motion and IDP at the transition segment compared with the fusion model. At the segment adjacent to the transition level, PH induced higher stress than IH model. Such differences may eventually influence the likelihood of ASD.

Effect of Fasting on Corneal Biomechanical and Structural Parameters.

PubMed

Sarici, Ahmet M; Yuksel Elgin, Cansu; Dikkaya, Funda

2016-07-01

To evaluate the effects of hunger and thirst on corneal biomechanical and structural parameters during Ramadan fasting. Corneal biomechanical properties and intraocular pressures of 29 eyes of 29 healthy subjects were evaluated by Reichert ocular response analyzer; and structural and anatomical properties of cornea and anterior eye chamber of same eyes were scanned with Oculus Pentacam anterior segment analyzer. Each eye has been evaluated at 8 am and 4 pm both during and 1 month after Ramadan. Changes of subjects' weight were calculated and their relationship with corneal biomechanical and structural parameters was assessed. Intraday changes in horizontal corneal astigmatism (p = 0.02), anterior chamber volume (p = 0.01), intraocular pressure associated with the Goldmann IOPg (p = 0.02) and corneal resistance factor (CRF) (p = 0.04) were significantly different when measured during the fasting period in Ramadan and 1 month thereafter. Moreover, when we compared 8 am measurements taken during and after Ramadan, we observed significant differences for anterior chamber volume (p = 0.04) and anterior chamber angle values (p = 0.03). Similarly, for 4 pm measurements, there were significant differences for IOPg (p = 0.01) and CRF values (p = 0.00). Fasting lasting for more than 12 h during Ramadan creates an important window of opportunity to investigate the response of anterior chamber of eye to hunger and thirst. The current study contributes to the existing literature on the effects of dietary habits and water intake on corneal and anterior chamber properties.

Biomechanical analysis for primary stability of shoulder arthrodesis in different resection situations.

PubMed

Lerch, Solveig; Keller, Sebastian; Kirsch, Ludger; Berndt, Thomas; Rühmann, Oliver

2013-07-01

Only very few publications dealing with shoulder arthrodesis after bone resection procedures and no biomechanical studies are available. The presented biomechanical analysis should ascertain the type of arthrodesis with the highest primary stability in different bone loss situations. On 24 fresh cadaveric shoulder specimens three different bone loss situations were investigated under the stress of abduction, adduction, anteversion and retroversion without destruction by the use of a material testing machine. In each of the testings a 16-hole reconstruction plate was used and compared to arthrodesis with an additional dorsal 6-hole plate. The primary stability of shoulder arthrodesis with a 16-hole reconstruction plate after humeral head resection could be increased significantly if an additional dorsal plate was used. However, no significant improvement with the additional plate was detected after resection of the acromion. Of all investigated forms, arthrodesis after humeral head resection with additional plate showed the highest and arthrodesis after humeral head resection without additional plate showed the lowest force values. The mean values for forces achieved in abduction and adduction were considerably higher than those in anteversion and retroversion. There are no consistent specifications of arthrodesis techniques after resection situation available, thus the presented biomechanical testings give important information about the most stable form of arthrodesis in different types of bone loss. These findings provide an opportunity to minimize complications such as pseudarthrosis for a satisfying clinical outcome. Copyright © 2013 Elsevier Ltd. All rights reserved.

Sub-cellular force microscopy in single normal and cancer cells

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

Babahosseini, H.; Carmichael, B.; Strobl, J.S.

2015-08-07

This work investigates the biomechanical properties of sub-cellular structures of breast cells using atomic force microscopy (AFM). The cells are modeled as a triple-layered structure where the Generalized Maxwell model is applied to experimental data from AFM stress-relaxation tests to extract the elastic modulus, the apparent viscosity, and the relaxation time of sub-cellular structures. The triple-layered modeling results allow for determination and comparison of the biomechanical properties of the three major sub-cellular structures between normal and cancerous cells: the up plasma membrane/actin cortex, the mid cytoplasm/nucleus, and the low nuclear/integrin sub-domains. The results reveal that the sub-domains become stiffer andmore » significantly more viscous with depth, regardless of cell type. In addition, there is a decreasing trend in the average elastic modulus and apparent viscosity of the all corresponding sub-cellular structures from normal to cancerous cells, which becomes most remarkable in the deeper sub-domain. The presented modeling in this work constitutes a unique AFM-based experimental framework to study the biomechanics of sub-cellular structures. - Highlights: • The cells are modeled as a triple-layered structure using Generalized Maxwell model. • The sub-domains include membrane/cortex, cytoplasm/nucleus, and nuclear/integrin. • Biomechanics of corresponding sub-domains are compared among normal and cancer cells. • Viscoelasticity of sub-domains show a decreasing trend from normal to cancer cells. • The decreasing trend becomes most significant in the deeper sub-domain.« less

Effect of osteoporosis on fixation of osseointegrated implants in rats.

PubMed

Li, Yunfeng; He, Sheng; Hua, Yunwei; Hu, Jing

2017-11-01

The effect of osteoporosis on implant osseointegration has been widely investigated, whereas osteoporosis may also newly occur in patient with previously osseointegrated implant. This study was designed to investigate the effect of osteoporosis on implant fixation in rats after successful osseointegration had been obtained. Seventy female Sprague-Dawley rats were included, and each animal received two titanium implants in the distal metaphysis of femur bilaterally. Eight weeks later, ten rats were sacrificed to confirm the establishment of implant osseointegration. All left rats were randomly subjected to bilateral ovariectomy (OVX) or sham operation. Three, six, and twelve weeks later, implant osseointegration, peri-implant bone tissue, and biomechanical properties of implant were analyzed. Right femurs with implants were used for micro-CT and histological analysis, and left femurs with implants were used for biomechanical test. Micro-CT, histology, and biomechanical test confirmed the destructive effect of OVX on previously osseointegrated implant in rats; when compared to sham-operated rats, peri-implant bone volume, trabecular architecture, bone-to-implant contact ratio, as well as biomechanical parameters decreased progressively within 12 weeks. Results also indicated that the effect of OVX on undisturbed bone (proximal tibiae) was much stronger than that on peri-implant bone. Osteoporosis produced a progressive negative effect on previously osseointegrated implant in distal femora of rats during 12 weeks. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2426-2432, 2017. © 2016 Wiley Periodicals, Inc.

A comparison of gait biomechanics of flip-flops, sandals, barefoot and shoes

PubMed Central

2013-01-01

Background Flip-flops and sandals are popular choices of footwear due to their convenience. However, the effects of these types of footwear on lower extremity biomechanics are still poorly understood. Therefore, the objective of this study was to investigate differences in ground reaction force (GRF), center of pressure (COP) and lower extremity joint kinematic and kinetic variables during level-walking in flip-flops, sandals and barefoot compared to running shoes. Methods Ten healthy males performed five walking trials in the four footwear conditions at 1.3 m/s. Three-dimensional GRF and kinematic data were simultaneously collected. Results A smaller loading rate of the 1st peak vertical GRF and peak propulsive GRF and greater peak dorsiflexion moment in early stance were found in shoes compared to barefoot, flip-flops and sandals. Barefoot walking yielded greater mediolateral COP displacement, flatter foot contact angle, increased ankle plantarflexion contact angle, and smaller knee flexion contact angle and range of motion compared to all other footwear. Conclusions The results from this study indicate that barefoot, flip-flops and sandals produced different peak GRF variables and ankle moment compared to shoes while all footwear yield different COP and ankle and knee kinematics compared to barefoot. The findings may be helpful to researchers and clinicians in understanding lower extremity mechanics of open-toe footwear. PMID:24196492

Knotted versus knotless suture bridge repair of the achilles tendon insertion: a biomechanical study.

PubMed

Cox, Joseph T; Shorten, Peter L; Gould, Gregory C; Markert, Ronald J; Barnett, Michael D; Laughlin, Richard T

2014-11-01

Surgical treatment of insertional Achilles tendinopathy often involves detachment and debridement of the Achilles tendon insertion. A recent study has shown that knotted suture bridge fixation of the Achilles to the calcaneus is biomechanically superior to single-row fixation, but there is an absence of literature on the use of different suture bridge constructs to repair the Achilles tendon. There will be no significant difference in the load to failure, mode of failure, tendon strain, tendon stiffness, repair site gapping, or footprint size when comparing knotted suture bridge repair to knotless suture bridge repair of the Achilles tendon after detachment for insertional Achilles tendinopathy. Controlled laboratory study. A single specimen from each pair of 10 cadaveric Achilles tendons was randomized to 1 of 2 Achilles insertion repair groups: knotted (n = 10) or knotless (n = 10) suture bridge repair. Repaired footprint size was measured, and then cyclic testing from 10 to 100 N for 2000 cycles was performed. This was followed by measurement of tendon strain, repair site displacement, load to failure, and tendon stiffness. The knotted suture bridge repair had a significantly higher load to failure compared with the knotless suture bridge (mean ± SD, 317.8 ± 93.6 N vs 196.1 ± 12.1 N, respectively; P = .001). All constructs failed at the tendon-suture interface. Tendon strain after cyclic testing was significantly greater in the knotless (1.20 ± 1.05) compared with the knotted (0.39 ± 0.4) suture repair groups (P = .011). There was no significant difference in footprint size between the knotted (230.3 ± 63.3 mm(2)) and knotless (248.5 ± 48.8 mm(2)) groups (P = .40). There was also no significant difference in stiffness (knotted = 76.4 ± 8.0 N/mm; knotless = 69.6 ± 10.9 N/mm; P = .17) and repair site displacement after cyclic testing (knotted = 2.8 ± 1.2 mm; knotless = 3.6 ± 1.1 mm; P = .17). During suture bridge repair of the Achilles tendon after detachment, knots at the proximal suture anchors significantly improve the biomechanical strength of the repair. This study demonstrated that the knotless suture bridge repair had a significantly lower load to failure than the knotted suture bridge. Surgeons should be aware of these biomechanical differences, as they influence the postoperative rehabilitation protocol and may lead to higher surgical complication rates. © 2014 The Author(s).

Biomechanical Evaluation of a Tooth Restored with High Performance Polymer PEKK Post-Core System: A 3D Finite Element Analysis.

PubMed

Lee, Ki-Sun; Shin, Joo-Hee; Kim, Jong-Eun; Kim, Jee-Hwan; Lee, Won-Chang; Shin, Sang-Wan; Lee, Jeong-Yol

2017-01-01

The aim of this study was to evaluate the biomechanical behavior and long-term safety of high performance polymer PEKK as an intraradicular dental post-core material through comparative finite element analysis (FEA) with other conventional post-core materials. A 3D FEA model of a maxillary central incisor was constructed. A cyclic loading force of 50 N was applied at an angle of 45° to the longitudinal axis of the tooth at the palatal surface of the crown. For comparison with traditionally used post-core materials, three materials (gold, fiberglass, and PEKK) were simulated to determine their post-core properties. PEKK, with a lower elastic modulus than root dentin, showed comparably high failure resistance and a more favorable stress distribution than conventional post-core material. However, the PEKK post-core system showed a higher probability of debonding and crown failure under long-term cyclic loading than the metal or fiberglass post-core systems.

Biomechanical Evaluation of a Tooth Restored with High Performance Polymer PEKK Post-Core System: A 3D Finite Element Analysis

PubMed Central

Shin, Joo-Hee; Kim, Jong-Eun; Kim, Jee-Hwan; Lee, Won-Chang; Shin, Sang-Wan

2017-01-01

The aim of this study was to evaluate the biomechanical behavior and long-term safety of high performance polymer PEKK as an intraradicular dental post-core material through comparative finite element analysis (FEA) with other conventional post-core materials. A 3D FEA model of a maxillary central incisor was constructed. A cyclic loading force of 50 N was applied at an angle of 45° to the longitudinal axis of the tooth at the palatal surface of the crown. For comparison with traditionally used post-core materials, three materials (gold, fiberglass, and PEKK) were simulated to determine their post-core properties. PEKK, with a lower elastic modulus than root dentin, showed comparably high failure resistance and a more favorable stress distribution than conventional post-core material. However, the PEKK post-core system showed a higher probability of debonding and crown failure under long-term cyclic loading than the metal or fiberglass post-core systems. PMID:28386547

An Investigation of Two Finite Element Modeling Solutions for Biomechanical Simulation Using a Case Study of a Mandibular Bone.

PubMed

Liu, Yun-Feng; Fan, Ying-Ying; Dong, Hui-Yue; Zhang, Jian-Xing

2017-12-01

The method used in biomechanical modeling for finite element method (FEM) analysis needs to deliver accurate results. There are currently two solutions used in FEM modeling for biomedical model of human bone from computerized tomography (CT) images: one is based on a triangular mesh and the other is based on the parametric surface model and is more popular in practice. The outline and modeling procedures for the two solutions are compared and analyzed. Using a mandibular bone as an example, several key modeling steps are then discussed in detail, and the FEM calculation was conducted. Numerical calculation results based on the models derived from the two methods, including stress, strain, and displacement, are compared and evaluated in relation to accuracy and validity. Moreover, a comprehensive comparison of the two solutions is listed. The parametric surface based method is more helpful when using powerful design tools in computer-aided design (CAD) software, but the triangular mesh based method is more robust and efficient.

An adaptive explanation for the horse-like shape of seahorses.

PubMed

Van Wassenbergh, Sam; Roos, Gert; Ferry, Lara

2011-01-25

The body shape of seahorses resembles the head and neck of horses because of their curved trunk, their ventrally bent head and their long snout. Seahorses evolved from ancestral, pipefish-like species, which have a straight body. Here, we use a biomechanical analysis and show that the seahorse's peculiar head, neck and trunk posture allows for the capture of small shrimps at larger distances from the eyes compared with pipefish. The results from the mathematical modelling were confirmed by kinematic data of prey-capturing syngnathids: compared with straight-bodied pipefish, all seahorse species studied consistently show an additional forward-reaching component in the path travelled by the mouth during their strikes at prey. This increased strike distance enlarges the volume of water they can probe for food, which is especially useful for tail-attached, sit-and-wait predators like seahorses. The biomechanics of prey capture thus provides a putative selective advantage that may explain the bending of the trunk into a horse-like shape.

Influence of emotion on the biomechanical organization of backward and forward step initiation.

PubMed

Yiou, Eric; Gendre, Manon; Deroche, Thomas; Le Bozec, Serge

2014-10-01

This study examined how pleasant and unpleasant emotional states influence the biomechanical organization of both forward and backward step initiation (SI). Participants (N = 31) purposely took a single step toward or away from a screen following the presentation of a pleasant (erotic), unpleasant (mutilation) or neutral (objects and landscapes) image. The main results showed that the reaction time for forward SI was shortened when individuals were exposed to pleasant pictures as compared with unpleasant pictures. The anticipatory whole-body center-of-mass velocity associated with backward SI, as well as the peak of center-of-mass velocity associated with forward SI both reached lower values when individuals were exposed to pleasant pictures as compared with neutral pictures. In contrast, unpleasant pictures did not significantly induce any change in the forward or backward SI parameters. Overall, these results obtained for whole-body approach/avoidance-like behaviors provided mitigated support for the so-called "motivational direction hypothesis."

Face-Referenced Measurement of Perioral Stiffness and Speech Kinematics in Parkinson's Disease

PubMed Central

Barlow, Steven M.; Lee, Jaehoon

2015-01-01

Purpose Perioral biomechanics, labial kinematics, and associated electromyographic signals were sampled and characterized in individuals with Parkinson's disease (PD) as a function of medication state. Method Passive perioral stiffness was sampled using the OroSTIFF system in 10 individuals with PD in a medication ON and a medication OFF state and compared to 10 matched controls. Perioral stiffness, derived as the quotient of resultant force and interoral angle span, was modeled with regression techniques. Labial movement amplitudes and integrated electromyograms from select lip muscles were evaluated during syllable production using a 4-D computerized motion capture system. Results Multilevel regression modeling showed greater perioral stiffness in patients with PD, consistent with the clinical correlate of rigidity. In the medication-OFF state, individuals with PD manifested greater integrated electromyogram levels for the orbicularis oris inferior compared to controls, which increased further after consumption of levodopa. Conclusions This study illustrates the application of biomechanical, electrophysiological, and kinematic methods to better understand the pathophysiology of speech motor control in PD. PMID:25629806

X-ray computed tomography library of shark anatomy and lower jaw surface models.

PubMed

Kamminga, Pepijn; De Bruin, Paul W; Geleijns, Jacob; Brazeau, Martin D

2017-04-11

The cranial diversity of sharks reflects disparate biomechanical adaptations to feeding. In order to be able to investigate and better understand the ecomorphology of extant shark feeding systems, we created a x-ray computed tomography (CT) library of shark cranial anatomy with three-dimensional (3D) lower jaw reconstructions. This is used to examine and quantify lower jaw disparity in extant shark species in a separate study. The library is divided in a dataset comprised of medical CT scans of 122 sharks (Selachimorpha, Chondrichthyes) representing 73 extant species, including digitized morphology of entire shark specimens. This CT dataset and additional data provided by other researchers was used to reconstruct a second dataset containing 3D models of the left lower jaw for 153 individuals representing 94 extant shark species. These datasets form an extensive anatomical record of shark skeletal anatomy, necessary for comparative morphological, biomechanical, ecological and phylogenetic studies.

Mechanical properties of human atherosclerotic intima tissue.

PubMed

Akyildiz, Ali C; Speelman, Lambert; Gijsen, Frank J H

2014-03-03

Progression and rupture of atherosclerotic plaques in coronary and carotid arteries are the key processes underlying myocardial infarctions and strokes. Biomechanical stress analyses to compute mechanical stresses in a plaque can potentially be used to assess plaque vulnerability. The stress analyses strongly rely on accurate representation of the mechanical properties of the plaque components. In this review, the composition of intima tissue and how this changes during plaque development is discussed from a mechanical perspective. The plaque classification scheme of the American Heart Association is reviewed and plaques originating from different vascular territories are compared. Thereafter, an overview of the experimental studies on tensile and compressive plaque intima properties are presented and the results are linked to the pathology of atherosclerotic plaques. This overview revealed a considerable variation within studies, and an enormous dispersion between studies. Finally, the implications of the dispersion in experimental data on the clinical applications of biomechanical plaque modeling are presented. Suggestions are made on mechanical testing protocol for plaque tissue and on using a standardized plaque classification scheme. This review identifies the current status of knowledge on plaque mechanical properties and the future steps required for a better understanding of the plaque type specific material properties. With this understanding, biomechanical plaque modeling may eventually provide essential support for clinical plaque risk stratification. Copyright © 2014 Elsevier Ltd. All rights reserved.

Immediate Biomechanical Implications of Transfer Component Skills Training on Independent Wheelchair Transfers.

PubMed

Tsai, Chung-Ying; Boninger, Michael L; Hastings, Jennifer; Cooper, Rory A; Rice, Laura; Koontz, Alicia M

2016-10-01

To evaluate the immediate effects of transfer training based on the Transfer Assessment Instrument (TAI) on the upper limb biomechanics during transfers. Pre-post intervention. Biomechanics laboratory. Full-time manual wheelchair users (N=24) performed 5 transfers to a level height bench, while their natural transfer skills were scored using the TAI, and their biomechanical data were recorded. Participants with 2 or more component skill deficits were invited to return to receive personalized transfer training. TAI part 1 summary scores and biomechanical variables calculated at the shoulder, elbow, and wrist joints were compared before and immediately after transfer training. Sixteen of the 24 manual wheelchair users met the criteria for training, and 11 manual wheelchair users came back for the revisit. Their TAI part 1 summary scores improved from 6.31±.98 to 9.92±.25. They had significantly smaller elbow range of motion, shoulder resultant moment, and rates of rise of elbow and wrist resultant forces on their trailing side during transfers after training (P<.05). On the leading side, shoulder maximum internal rotation and elevation angles, and shoulder resultant moments and rates of rise of shoulder resultant force and moment decreased after training (P<.04). The TAI-based training showed short-term beneficial biomechanical effects on wheelchair users' upper limbs, such as better shoulder positioning and lower joint loadings. If the skills are practiced longer-term, they may help protect the upper limbs from developing pain and injuries. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Biomechanical assessment and 3D finite element analysis of the treatment of tibial fractures using minimally invasive percutaneous plates

PubMed Central

Hu, Xin-Jia; Wang, Hua

2017-01-01

The aim of the present study was to investigate the biomechanical effects of varying the length of a limited contact-dynamic compression plate (LC-DCP) and the number and position of screws on middle tibial fractures, and to provide biomechanical evidence regarding minimally invasive plate osteosynthesis (MIPO). For biomechanical testing, 60 tibias from cadavers (age at mortality, 20–40 years) were used to create middle and diagonal fracture models without defects. Tibias were randomly grouped and analyzed by biomechanic and three-dimensional (3D) finite element analysis. The differences among LC-DCPs of different lengths (6-, 10- and 14-hole) with 6 screws, 14-hole LC-DCPs with different numbers of screws (6, 10 and 14), and 14-hole LC-DCPs with 6 screws at different positions with regard to mechanical characteristics, including compressing, torsion and bending, were examined. The 6-hole LC-DCP had greater vertical compression strain compared with the 10- and 14-hole LC-DCPs (P<0.01), and the 14-hole LC-DCP had greater lateral strain than the 6- and 10-hole LC-DCPs (P<0.01). Furthermore, significant differences in torque were observed among the LC-DPs of different lengths (P<0.01). For 14-hole LC-DCPs with different numbers of screws, no significant differences in vertical strain, lateral strain or torque were detected (P>0.05). However, plates with 14 screws had greater vertical strain compared with those fixed with 6 or 10 screws (P<0.01). For 4-hole LC-DCPs with screws at different positions, vertical compression strain values were lowest for plates with screws at positions 1, 4, 7, 8, 11 and 14 (P<0.01). The lateral strain values and vertical strain values for plates with screws at positions 1, 3, 6, 9, 12 and 14 were significantly lower compared with those at the other positions (P<0.01), and torque values were also low. Thus, the 14-hole LC-DCP was the most stable against vertical compression, torsion and bending, and the 6-hole LC-DCP was the least stable. However, the use of 14 screws with a 14-hole LC-DCP provided less stability against bending than did 6 or 10 screws. Furthermore, fixation with distributed screws, in which some screws were close to the fracture line, provided good stability against compression and torsion, while fixation with screws at the ends of the LC-DCP provided poor stability against bending, compressing and torsion. PMID:28781632

A systematic review: the influence of real time feedback on wheelchair propulsion biomechanics.

PubMed

Symonds, Andrew; Barbareschi, Giulia; Taylor, Stephen; Holloway, Catherine

2018-01-01

Clinical guidelines recommend that, in order to minimize upper limb injury risk, wheelchair users adopt a semi-circular pattern with a slow cadence and a large push arc. To examine whether real time feedback can be used to influence manual wheelchair propulsion biomechanics. Clinical trials and case series comparing the use of real time feedback against no feedback were included. A general review was performed and methodological quality assessed by two independent practitioners using the Downs and Black checklist. The review was completed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) guidelines. Six papers met the inclusion criteria. Selected studies involved 123 participants and analysed the effect of visual and, in one case, haptic feedback. Across the studies it was shown that participants were able to achieve significant changes in propulsion biomechanics, when provided with real time feedback. However, the effect of targeting a single propulsion variable might lead to unwanted alterations in other parameters. Methodological assessment identified weaknesses in external validity. Visual feedback could be used to consistently increase push arc and decrease push rate, and may be the best focus for feedback training. Further investigation is required to assess such intervention during outdoor propulsion. Implications for Rehabilitation Upper limb pain and injuries are common secondary disorders that negatively affect wheelchair users' physical activity and quality of life. Clinical guidelines suggest that manual wheelchair users should aim to propel with a semi-circular pattern with low a push rate and large push arc in the range in order to minimise upper limbs' loading. Real time visual and haptic feedback are effective tools for improving propulsion biomechanics in both complete novices and experienced manual wheelchair users.

The influence of foot hyperpronation on pelvic biomechanics during stance phase of the gait: A biomechanical simulation study.

PubMed

Yazdani, Farzaneh; Razeghi, Mohsen; Karimi, Mohammad Taghi; Raeisi Shahraki, Hadi; Salimi Bani, Milad

2018-05-01

Despite the theoretical link between foot hyperpronation and biomechanical dysfunction of the pelvis, the literature lacks evidence that confirms this assumption in truly hyperpronated feet subjects during gait. Changes in the kinematic pattern of the pelvic segment were assessed in 15 persons with hyperpronated feet and compared to a control group of 15 persons with normally aligned feet during the stance phase of gait based on biomechanical musculoskeletal simulation. Kinematic and kinetic data were collected while participants walked at a comfortable self-selected speed. A generic OpenSim musculoskeletal model with 23 degrees of freedom and 92 muscles was scaled for each participant. OpenSim inverse kinematic analysis was applied to calculate segment angles in the sagittal, frontal and horizontal planes. Principal component analysis was employed as a data reduction technique, as well as a computational tool to obtain principal component scores. Independent-sample t-test was used to detect group differences. The difference between groups in scores for the first principal component in the sagittal plane was statistically significant (p = 0.01; effect size = 1.06), but differences between principal component scores in the frontal and horizontal planes were not significant. The hyperpronation group had greater anterior pelvic tilt during 20%-80% of the stance phase. In conclusion, in persons with hyperpronation we studied the role of the pelvic segment was mainly to maintain postural balance in the sagittal plane by increasing anterior pelvic inclination. Since anterior pelvic tilt may be associated with low back symptoms, the evaluation of foot posture should be considered in assessing the patients with low back and pelvic dysfunction.

A biomechanical analysis of sublaminar and subtransverse process fixation using metal wires and polyethylene cables.

PubMed

Fujita, Masaru; Diab, Mohammad; Xu, Zheng; Puttlitz, Christian M

2006-09-01

An in vitro biomechanical calf thoracic spine study. To evaluate the biomechanical stability of sublaminar and subtransverse process fixation using stainless steel wires and ultra-high molecular weight polyethylene (UHMWPE) cables. It is commonly held that transverse process fixation provides less stability than sublaminar fixation. To our knowledge, this is the first biomechanical study to compare the stability afforded by sublaminar fixation and subtransverse process fixation using metal wire and UHMWPE cable before and after cyclic loading. There were 6 fresh-frozen calf thoracic spines (T4-T9) used to determine the sublaminar fixation stiffness and subtransverse process fixation stiffness in each group. Double strands of 18-gauge stainless steel wire, 3 and 5 mm-width UHMWPE cable (Nesplon; Alfresa, Inc., Osaka, Japan) were applied to each spine. Cyclic pure flexion-extension moment loading (2 Nm, 0.5 Hz, 5000 cycles) was applied after the initial stability was analyzed by measuring the range of motion. Statistical analyses were used to delineate differences between the various experimental groups. Subtransverse process wiring was more stable than sublaminar wiring after cyclic loading in flexion-extension (P < 0.05). There were no significant differences between each group in lateral bending and axial rotation after cyclic loading. Sublaminar stainless steel wiring was more stable than sublaminar 3 and 5-mm cable before and after cyclic loading in axial rotation (P < 0.01). Acute subtransverse process fixation using 3-mm cable was less stable after cyclic loading in axial rotation (P < 0.05). All other groups did not produce statistically significant differences. Subtransverse process fixation provides at least as much stability as sublaminar fixation. A 5-mm UHMWPE cable and stainless steel wire result in equivalent sublaminar and subtransverse process stability.

Ulnar neuropathy and ulnar neuropathy-like symptoms in relation to biomechanical exposures assessed by a job exposure matrix: a triple case-referent study.

PubMed

Svendsen, Susanne Wulff; Johnsen, Birger; Fuglsang-Frederiksen, Anders; Frost, Poul

2012-11-01

We aimed to evaluate relations between occupational biomechanical exposures and (1) ulnar neuropathy confirmed by electroneurography (ENG) and (2) ulnar neuropathy-like symptoms with normal ENG. In this triple case-referent study, we identified all patients aged 18-65 years, examined with ENG at a neurophysiological department on suspicion of ulnar neuropathy, 2001-2007. We mailed a questionnaire to 546 patients with ulnar neuropathy, 633 patients with ulnar neuropathy-like symptoms and two separate groups of community referents, matched on sex, age and primary care centre (risk set sampling). The two patient groups were also compared to each other directly. We constructed a Job Exposure Matrix to provide estimates of exposure to non-neutral postures, repetitive movements, hand-arm vibrations and forceful work. Conditional and unconditional logistic regressions were used. The proportion who responded was 59%. Ulnar neuropathy was related to forceful work with an exposure-response pattern reaching an OR of 3.85 (95% CI 2.04 to 7.24); non-neutral postures strengthened effects of forceful work. No relation was observed with repetitive movements. Ulnar neuropathy-like symptoms were related to repetitive movements with an OR of 1.89 (95% CI 1.01 to 3.52) in the highest-exposure category (≥2.5 h/day); forceful work was unrelated to the outcome. Ulnar neuropathy and ulnar neuropathy-like symptoms differed with respect to associations with occupational biomechanical exposures. Findings suggested specific effects of forceful work on the ulnar nerve. Thus, results corroborated the importance of an electrophysiological diagnosis when evaluating risk factors for ulnar neuropathy. Preventive effects may be achieved by reducing biomechanical exposures at work.

Corneal biomechanical properties from air-puff corneal deformation imaging

NASA Astrophysics Data System (ADS)

Marcos, Susana; Kling, Sabine; Bekesi, Nandor; Dorronsoro, Carlos

2014-02-01

The combination of air-puff systems with real-time corneal imaging (i.e. Optical Coherence Tomography (OCT), or Scheimpflug) is a promising approach to assess the dynamic biomechanical properties of the corneal tissue in vivo. In this study we present an experimental system which, together with finite element modeling, allows measurements of corneal biomechanical properties from corneal deformation imaging, both ex vivo and in vivo. A spectral OCT instrument combined with an air puff from a non-contact tonometer in a non-collinear configuration was used to image the corneal deformation over full corneal cross-sections, as well as to obtain high speed measurements of the temporal deformation of the corneal apex. Quantitative analysis allows direct extraction of several deformation parameters, such as apex indentation across time, maximal indentation depth, temporal symmetry and peak distance at maximal deformation. The potential of the technique is demonstrated and compared to air-puff imaging with Scheimpflug. Measurements ex vivo were performed on 14 freshly enucleated porcine eyes and five human donor eyes. Measurements in vivo were performed on nine human eyes. Corneal deformation was studied as a function of Intraocular Pressure (IOP, 15-45 mmHg), dehydration, changes in corneal rigidity (produced by UV corneal cross-linking, CXL), and different boundary conditions (sclera, ocular muscles). Geometrical deformation parameters were used as input for inverse finite element simulation to retrieve the corneal dynamic elastic and viscoelastic parameters. Temporal and spatial deformation profiles were very sensitive to the IOP. CXL produced a significant reduction of the cornea indentation (1.41x), and a change in the temporal symmetry of the corneal deformation profile (1.65x), indicating a change in the viscoelastic properties with treatment. Combining air-puff with dynamic imaging and finite element modeling allows characterizing the corneal biomechanics in-vivo.

Biomechanical analysis of intramedullary vs. superior plate fixation of transverse midshaft clavicle fractures.

PubMed

Wilson, David J; Scully, William F; Min, Kyong S; Harmon, Tess A; Eichinger, Josef K; Arrington, Edward D

2016-06-01

Middle-third clavicle fractures represent 2% to 4% of all skeletal trauma in the United States. Treatment options include intramedullary (IM) as well as plate and screw (PS) constructs. The purpose of this study was to analyze the biomechanical stability of a specific IM system compared with nonlocking PS fixation under low-threshold physiologic load. Twenty fourth-generation Sawbones (Pacific Research Laboratories, Vashon, WA, USA) with a simulated middle-third fracture pattern were repaired with either an IM device (n = 10) or superiorly positioned nonlocking PS construct (n = 10). Loads were modeled to simulate physiologic load. Combined axial compression and torsion forces were sequentially increased until failure. Data were analyzed on the basis of loss of rotational stability using 3 criteria: early (10°), clinical (30°), and terminal (120°). No significant difference was noted between constructs in early loss of rotational stability (P > .05). The PS group was significantly more rotationally stable than the IM group on the basis of clinical and terminal criteria (P < .05 for both). All test constructs failed in rotational stability. When tested under physiologic load, fixation failure occurred from loss of rotational stability. No statistical difference was seen between groups under early physiologic loads. However, during load to failure, the PS group was statistically more rotationally stable than the IM group. Given the clavicle's function as a bony strut for the upper extremity and the biomechanical results demonstrated, rotational stability should be carefully considered during surgical planning and postoperative advancement of activity in patients undergoing operative fixation of middle-third clavicle fractures. Basic Science Study; Biomechanics. Published by Elsevier Inc.

Study on diagnosis of micro-biomechanical structure using optical coherence tomography

NASA Astrophysics Data System (ADS)

Saeki, Souichi; Hashimoto, Youhei; Saito, Takashi; Hiro, Takafumi; Matsuzaki, Masunori

2007-02-01

Acute coronary syndromes, e.g. myocardial infarctions, are caused by the rupture of unstable plaques on coronary arteries. The stability of plaque, which depends on biomechanical properties of fibrous cap, should be diagnosed crucially. Recently, Optical Coherence Tomography (OCT) has been developed as a cross-sectional imaging method of microstructural biological tissue with high resolution 1~10 μm. Multi-functional OCT system has been promising, e.g. an estimator of biomechanical characteristics. It has been, however, difficult to estimate biomechanical characteristics, because OCT images have just speckle patterns by back-scattering light from tissue. In this study, presented is Optical Coherence Straingraphy (OCS) on the basis of OCT system, which can diagnose tissue strain distribution. This is basically composed of Recursive Cross-correlation technique (RC), which can provide a displacement vector distribution with high resolution. Furthermore, Adjacent Cross-correlation Multiplication (ACM) is introduced as a speckle noise reduction method. Multiplying adjacent correlation maps can eliminate anomalies from speckle noise, and then can enhance S/N in the determination of maximum correlation coefficient. Error propagation also can be further prevented by introducing to the recursive algorithm (RC). In addition, the spatial vector interpolation by local least square method is introduced to remove erroneous vectors and smooth the vector distribution. This was numerically applied to compressed elastic heterogeneous tissue samples to carry out the accuracy verifications. Consequently, it was quantitatively confirmed that its accuracy of displacement vectors and strain matrix components could be enhanced, comparing with the conventional method. Therefore, the proposed method was validated by the identification of different elastic objects with having nearly high resolution for that defined by optical system.

Biomechanical and functional variation in rat sciatic nerve following cuff electrode implantation

PubMed Central

2014-01-01

Background Nerve cuff electrodes are commonly and successfully used for stimulating peripheral nerves. On the other hand, they occasionally induce functional and morphological changes following chronic implantation, for reasons not always clear. We hypothesize that restriction of nerve mobility due to cuff implantation may alter nerve conduction. Methods We quantified acute changes in nerve-muscle electrophysiology, using electromyography, and nerve kinematics in anesthetized Sprague Dawley rat sciatic nerves during controlled hindlimb joint movement. We compared electrophysiological and biomechanical response in uncuffed nerves and those secured within a cuff electrode using analysis of variance (ANOVA) and regression analysis. Results Tethering resulting from cuff implantation resulted in altered nerve strain and a complex biomechanical environment during joint movement. Coincident with biomechanical changes, electromyography revealed significantly increased variability in the response of conduction latency and amplitude in cuffed, but not free, nerves following joint movement. Conclusion Our findings emphasize the importance of the mechanical interface between peripheral nerves and their devices on neurophysiological performance. This work has implications for nerve device design, implantation, and prediction of long-term efficacy. PMID:24758405

Liquifying PLDLLA Anchor Fixation in Achilles Reconstruction for Insertional Tendinopathy.

PubMed

Boden, Stephanie A; Boden, Allison L; Mignemi, Danielle; Bariteau, Jason T

2018-04-01

Insertional Achilles tendinopathy (IAT) is a frequent cause of posterior heel pain and is often associated with Haglund's deformity. Surgical correction for refractory cases of IAT has been well studied; however, the method of tendon fixation to bone in these procedures remains controversial, and to date, no standard technique has been identified for tendon fixation in these surgeries. Often, after Haglund's resection, there is large exposed cancellous surface for Achilles reattachment, which may require unique fixation to optimize outcomes. Previous studies have consistently demonstrated improved patient outcomes after Achilles tendon reconstruction with early rehabilitation with protected weight bearing, evidencing the need for a strong and stable anchoring of the Achilles tendon that allows early weight bearing without tendon morbidity. In this report, we highlight the design, biomechanics, and surgical technique of Achilles tendon reconstruction with Haglund's deformity using a novel technique that utilizes ultrasonic energy to liquefy the suture anchor, allowing it to incorporate into surrounding bone. Biomechanical studies have demonstrated superior strength of the suture anchor utilizing this novel technique as compared with prior techniques. However, future research is needed to ensure that outcomes of this technique are favorable when compared with outcomes using traditional suture anchoring methods. Level V: Operative technique.

The anatomy and biomechanics of running.

PubMed

Nicola, Terry L; Jewison, David J

2012-04-01

To understand the normal series of biomechanical events of running, a comparative assessment to walking is helpful. Closed kinetic chain through the lower extremities, control of the lumbopelvic mechanism, and overall symmetry of movement has been described well enough that deviations from normal movement can now be associated with specific overuse injuries experienced by runners. This information in combination with a history of the runner's errors in their training program will lead to a more comprehensive treatment and prevention plan for related injuries.

Using Clinical Gait Case Studies to Enhance Learning in Biomechanics

ERIC Educational Resources Information Center

Chester, Victoria

2011-01-01

Clinical case studies facilitate the development of clinical reasoning strategies through knowledge and integration of the basic sciences. Case studies have been shown to be more effective in developing problem-solving abilities than the traditional lecture format. To enhance the learning experiences of students in biomechanics, clinical case…

Effects of antibacterial nanostructured composite films on vascular stents: hemodynamic behaviors, microstructural characteristics, and biomechanical properties.

PubMed

Cheng, Han-Yi; Hsiao, Wen-Tien; Lin, Li-Hsiang; Hsu, Ya-Ju; Sinrang, Andi Wardihan; Ou, Keng-Liang

2015-01-01

The purpose of this research was to investigate stresses resulting from different thicknesses and compositions of hydrogenated Cu-incorporated diamond-like carbon (a-C:H/Cu) films at the interface between vascular stent and the artery using three-dimensional reversed finite element models (FEMs). Blood flow velocity variation in vessels with plaques was examined by angiography, and the a-C:H/Cu films were characterized by transmission electron microscopy to analyze surface morphology. FEMs were constructed using a computer-aided reverse design system, and the effects of antibacterial nanostructured composite films in the stress field were investigated. The maximum stress in the vascular stent occurred at the intersections of net-like structures. Data analysis indicated that the stress decreased by 15% in vascular stents with antibacterial nanostructured composite films compared to the control group, and the stress decreased with increasing film thickness. The present results confirmed that antibacterial nanostructured composite films improve the biomechanical properties of vascular stents and release abnormal stress to prevent restenosis. The results of the present study offer the clinical benefit of inducing superior biomechanical behavior in vascular stents. © 2014 Wiley Periodicals, Inc.

Cervical biomechanics and neck pain of "head-spinning" breakdancers.

PubMed

Kauther, M D; Piotrowski, M; Hussmann, B; Lendemans, S; Wedemeyer, C; Jaeger, M

2014-05-01

The cervical spine of breakdancers is at great risk due to reversed body loading during headspin manoeuvers. This study focused on the cervical biomechanics of breakdancers and a correlation with neck pain. A standardized interview and biomechanical testing of the cervical spine of 25 participants with "headspin" ability ages 16-34 years and an age-matched cohort of 25 participants without any cervical spine problems was conducted. Neck pain history, Neck Disability Index (NDI), cervical range of motion (CROM) and cervical torque were recorded. The "headspin" group reported significantly better subjective fitness, more cervical complaints, higher pain intensity, a longer history of neck pain and a worse NDI compared to the "normal" collective. The "headspin" group showed a 2-2.5 times higher rate of neck pain than the normal population, with increased cervical flexion (p<0.05) and increased cervical torque in all planes (p<0.001). The CROM showed a negative moderate to strong correlation with NDI, pain intensity and history of neck pain. Sports medicine practitioners should be aware of headspin maneuver accidents that pose the risk of fractures, dislocations and spinal cord injuries of breakdancers. © Georg Thieme Verlag KG Stuttgart · New York.

Total hip arthroplasty of dysplastic hip after previous Chiari pelvic osteotomy.

PubMed

Minoda, Yukihide; Kadowaki, Toru; Kim, Mitsunari

2006-08-01

Many reports have suggested that Chiari pelvic osteotomy would improve the results of acetabular component placement and fixation in subsequent total hip arthroplasty. However, little is known concerning the biomechanical, radiological, and clinical effects of Chiari pelvic osteotomy on subsequent total hip arthroplasty. Ten total hip arthroplasties for developmental dysplasia of the hip after previous Chiari pelvic osteotomy (Chiari group) were compared with 20 total hip arthroplasties for developmental dysplasia of the hip without previous surgery (control group). Preoperative patient demographic data and operative technique were well matched between the groups. The mean duration of follow-up was 3.0 years. Biomechanical, radiological, and clinical evaluations were performed. No acetabular or femoral components exhibited loosening. All patients had good or excellent clinical score according to the Merle d'Aubigne-Postel rating system at the most recent follow-up. Abductor force and joint force were smaller in the Chiari group, although long operative time, more blood loss, and verticalization of joint force were noted in this group. This limited study suggested that Chiari pelvic osteotomy changed the biomechanical features of the hip joint, and that this alteration might have compromised subsequent total hip arthroplasty.

Evaluating the effects of pentoxifylline administration on experimental pressure sores in rats by biomechanical examinations

PubMed Central

Velaei, Kobra; Torkman, Giti; Rezaie, Fatemealsadat; Amini, Abdollah; Noruzian, Mohsen; Tavassol, Azaedh; Bayat, Mehernoush

2012-01-01

This study used a biomechanical test to evaluate the effects of pentoxifylline administration on the wound healing process of an experimental pressure sore induced in rats. Under general anesthesia and sterile conditions, experimental pressure sores generated by no. 25 Halsted mosquito forceps were inflicted on 12 adult male rats. Pentoxifylline was injected intraperitoneally at a dose of 50 mg/kg daily from the day the pressure sore was generated, for a period of 20 days. At the end of 20 days, rats were sacrificed and skin samples extracted. Samples were biomechanically examined by a material testing instrument for maximum stress (N mm2), work up to maximum force (N), and elastic stiffness (N/mm). In the experimental group, maximum stress (2.05±0.15) and work up to maximum force (N/mm) (63.75±4.97) were significantly higher than the control group (1.3±0.27 and 43.3±14.96, P=0.002 and P=0.035, respectively). Pentoxifylline administration significantly accelerated the wound healing process in experimental rats with pressure sores, compared to that of the control group. PMID:23091522

Evaluating the effects of pentoxifylline administration on experimental pressure sores in rats by biomechanical examinations.

PubMed

Velaei, Kobra; Bayat, Mohammad; Torkman, Giti; Rezaie, Fatemealsadat; Amini, Abdollah; Noruzian, Mohsen; Tavassol, Azaedh; Bayat, Mehernoush

2012-09-01

This study used a biomechanical test to evaluate the effects of pentoxifylline administration on the wound healing process of an experimental pressure sore induced in rats. Under general anesthesia and sterile conditions, experimental pressure sores generated by no. 25 Halsted mosquito forceps were inflicted on 12 adult male rats. Pentoxifylline was injected intraperitoneally at a dose of 50 mg/kg daily from the day the pressure sore was generated, for a period of 20 days. At the end of 20 days, rats were sacrificed and skin samples extracted. Samples were biomechanically examined by a material testing instrument for maximum stress (N mm(2)), work up to maximum force (N), and elastic stiffness (N/mm). In the experimental group, maximum stress (2.05±0.15) and work up to maximum force (N/mm) (63.75±4.97) were significantly higher than the control group (1.3±0.27 and 43.3±14.96, P=0.002 and P=0.035, respectively). Pentoxifylline administration significantly accelerated the wound healing process in experimental rats with pressure sores, compared to that of the control group.

Embryo mechanics: balancing force production with elastic resistance during morphogenesis.

PubMed

Davidson, Lance A

2011-01-01

Morphogenesis requires the spatial and temporal control of embryo mechanics, including force production and mechanical resistance to those forces, to coordinate tissue deformation and large-scale movements. Thus, biomechanical processes play a key role in directly shaping the embryo. Additional roles for embryo mechanics during development may include the patterning of positional information and to provide feedback to ensure the success of morphogenetic movements in shaping the larval body and organs. To understand the multiple roles of mechanics during development requires familiarity with engineering principles of the mechanics of structures, the viscoelastic properties of biomaterials, and the integration of force and stress within embryonic structures as morphogenesis progresses. In this chapter, we review the basic engineering principles of biomechanics as they relate to morphogenesis, introduce methods for quantifying embryo mechanics and the limitations of these methods, and outline a formalism for investigating the role of embryo mechanics in birth defects. We encourage the nascent field of embryo mechanics to adopt standard engineering terms and test methods so that studies of diverse organisms can be compared and universal biomechanical principles can be revealed. Copyright © 2011 Elsevier Inc. All rights reserved.

The effect of lower body stabilization and different writing tools on writing biomechanics in children with cerebral palsy.

PubMed

Cheng, Hsin-Yi Kathy; Lien, Yueh-Ju; Yu, Yu-Chun; Ju, Yan-Ying; Pei, Yu-Cheng; Cheng, Chih-Hsiu; Wu, David Bin-Chia

2013-04-01

A high percentage of children with cerebral palsy (CP) have difficulty keeping up with the handwriting demands at school. Previous studies have addressed the effects of proper sitting and writing tool on writing performance, but less on body biomechanics. The aim of this study was to investigate the influence of lower body stabilization and pencil design on body biomechanics in children with CP. Fourteen children (12.31±4.13 years old) with CP were recruited for this study. A crossover repeated measures design was employed, with two independent variables: lower body stabilization (with/without) and pencil (regular/assigned grip height/biaxial). The writing task was to trace the Archimedean spiral mazes. Electromyography (EMG) of the upper extremity, the wrist flexion/extension movements, and the whole body photography were recorded to quantify the changes in posture and upper extremity biomechanics. Two-way repeated measures ANOVA was used for statistical analysis. No significant main effects were revealed in the EMG and wrist kinematics. The lower body stabilization significantly decreased the trunk lateral and forward deviations, and the visual focus-vertical angle. The biaxial pencil and the assigned grip height design significantly decreased the head, shoulder, trunk, and pelvic deviations compared with the regular design. The results indicated that the lower body positioning was effective in improving the trunk posture. A pencil with an assigned grip height or with a biaxial design could improve head, shoulder, trunk and pelvic alignment, but did not influence the muscle exertion of the upper extremity. This study could provide guidelines for parents, teachers and clinicians regarding the selection of writing tools and the knowledge of proper positioning for the children with handwriting difficulties. Further analyses can focus on the design, modification and clinical application of assitive sitting and writing devices for the use in children with handwriting difficulties. Copyright © 2013 Elsevier Ltd. All rights reserved.

The History of Biomechanics in Total Hip Arthroplasty.

PubMed

Houcke, Jan Van; Khanduja, Vikas; Pattyn, Christophe; Audenaert, Emmanuel

2017-01-01

Biomechanics of the hip joint describes how the complex combination of osseous, ligamentous, and muscular structures transfers the weight of the body from the axial skeleton into the appendicular skeleton of the lower limbs. Throughout history, several biomechanical studies based on theoretical mathematics, in vitro , in vivo as well as in silico models have been successfully performed. The insights gained from these studies have improved our understanding of the development of mechanical hip pathologies such as osteoarthritis, hip fractures, and developmental dysplasia of the hip. The main treatment of end-stage degeneration of the hip is total hip arthroplasty (THA). The increasing number of patients undergoing this surgical procedure, as well as their demand for more than just pain relief and leading an active lifestyle, has challenged surgeons and implant manufacturers to deliver higher function as well as longevity with the prosthesis. The science of biomechanics has played and will continue to play a crucial and integral role in achieving these goals. The aim of this article, therefore, is to present to the readers the key concepts in biomechanics of the hip and their application to THA.

Analysis of Big Data in Gait Biomechanics: Current Trends and Future Directions.

PubMed

Phinyomark, Angkoon; Petri, Giovanni; Ibáñez-Marcelo, Esther; Osis, Sean T; Ferber, Reed

2018-01-01

The increasing amount of data in biomechanics research has greatly increased the importance of developing advanced multivariate analysis and machine learning techniques, which are better able to handle "big data". Consequently, advances in data science methods will expand the knowledge for testing new hypotheses about biomechanical risk factors associated with walking and running gait-related musculoskeletal injury. This paper begins with a brief introduction to an automated three-dimensional (3D) biomechanical gait data collection system: 3D GAIT, followed by how the studies in the field of gait biomechanics fit the quantities in the 5 V's definition of big data: volume, velocity, variety, veracity, and value. Next, we provide a review of recent research and development in multivariate and machine learning methods-based gait analysis that can be applied to big data analytics. These modern biomechanical gait analysis methods include several main modules such as initial input features, dimensionality reduction (feature selection and extraction), and learning algorithms (classification and clustering). Finally, a promising big data exploration tool called "topological data analysis" and directions for future research are outlined and discussed.

Analysis of occupational stress in a high fashion clothing factory with upper limb biomechanical overload.

PubMed

Forcella, Laura; Bonfiglioli, Roberta; Cutilli, Piero; Siciliano, Eugenio; Di Donato, Angela; Di Nicola, Marta; Antonucci, Andrea; Di Giampaolo, Luca; Boscolo, Paolo; Violante, Francesco Saverio

2012-07-01

To study job stress and upper limb biomechanical overload due to repetitive and forceful manual activities in a factory producing high fashion clothing. A total of 518 workers (433 women and 85 men) were investigated to determine anxiety, occupational stress (using the Italian version of the Karasek Job Content Questionnaire) and perception of symptoms (using the Italian version of the Somatization scale of Symptom Checklist SCL-90). Biomechanical overload was analyzed using the OCRA Check list. Biomechanical assessment did not reveal high-risk jobs, except for cutting. Although the perception of anxiety and job insecurity was within the normal range, all the workers showed a high level of job strain (correlated with the perception of symptoms) due to very low decision latitude. Occupational stress resulted partially in line with biomechanical risk factors; however, the perception of low decision latitude seems to play a major role in determining job strain. Interactions between physical and psychological factors cannot be demonstrated. Anyway, simultaneous long-term monitoring of occupational stress features and biomechanical overload could guide workplace interventions aimed at reducing the risk of adverse health effects.

Biomechanics of the lower thoracic spine after decompression and fusion: a cadaveric analysis.

PubMed

Lubelski, Daniel; Healy, Andrew T; Mageswaran, Prasath; Benzel, Edward C; Mroz, Thomas E

2014-09-01

Few studies have evaluated the extent of biomechanical destabilization of thoracic decompression on the upper and lower thoracic spine. The present study evaluates lower thoracic spinal stability after laminectomy, unilateral facetectomy, and unilateral costotransversectomy in thoracic spines with intact sternocostovertebral articulations. To assess the biomechanical impact of decompression and fixation procedures on lower thoracic spine stability. Biomechanical cadaveric study. Sequential surgical decompression (laminectomy, unilateral facetectomy, unilateral costotransversectomy) and dorsal fixation were performed on the lower thoracic spine (T8-T9) of human cadaveric spine specimens with intact rib cages (n=10). An industrial robot was used to apply pure moments to simulate flexion-extension (FE), lateral bending (LB), and axial rotation (AR) in the intact specimens and after decompression and fixation. Global range of motion (ROM) between T1-T12 and intrinsic ROM between T7-T11 were measured for each specimen. The decompression procedures caused no statistically significant change in either global or intrinsic ROM compared with the intact state. Instrumentation, however, reduced global motion for AR (45° vs. 30°, p=.0001), FE (24° vs. 19°, p=.02), and LB (47° vs. 36°, p=.0001) and for intrinsic motion for AR (17° vs. 4°, p=.0001), FE (8° vs. 1°, p=.0001), and LB (12° vs. 1°, p=.0001). No significant differences were identified between decompression of the upper versus lower thoracic spine, with trends toward significantly greater ROM for AR and lower ROM for LB in the lower thoracic spine. The lower thoracic spine was not destabilized by sequential unilateral decompression procedures. Addition of dorsal fixation increased segment rigidity at intrinsic levels and also reduced overall ROM of the lower thoracic spine to a greater extent than did fusing the upper thoracic spine (level of the true ribs). Despite the lack of true ribs, the lower thoracic spine was not significantly different compared with the upper thoracic spine in FE and LB after decompression, although there were trends toward significance for greater AR after decompression. In certain patients, instrumentation may not be needed after unilateral decompression of the lower thoracic spine; further validation and additional clinical studies are warranted. Copyright © 2014 Elsevier Inc. All rights reserved.

Biomechanics of occlusion--implications for oral rehabilitation.

PubMed

Peck, C C

2016-03-01

The dental occlusion is an important aspect of clinical dentistry; there are diverse functional demands ranging from highly precise tooth contacts to large crushing forces. Further, there are dogmatic, passionate and often diverging views on the relationship between the dental occlusion and various diseases and disorders including temporomandibular disorders, non-carious cervical lesions and tooth movement. This study provides an overview of the biomechanics of the masticatory system in the context of the dental occlusion's role in function. It explores the adaptation and precision of dental occlusion, its role in bite force, jaw movement, masticatory performance and its influence on the oro-facial musculoskeletal system. Biomechanics helps us better understand the structure and function of biological systems and consequently an understanding of the forces on, and displacements of, the dental occlusion. Biomechanics provides insight into the relationships between the dentition, jaws, temporomandibular joints, and muscles. Direct measurements of tooth contacts and forces are difficult, and biomechanical models have been developed to better understand the relationship between the occlusion and function. Importantly, biomechanical research will provide knowledge to help correct clinical misperceptions and inform better patient care. The masticatory system demonstrates a remarkable ability to adapt to a changing biomechanical environment and changes to the dental occlusion or other components of the musculoskeletal system tend to be well tolerated. © 2015 John Wiley & Sons Ltd.

Effects of Ankle Arthrodesis on Biomechanical Performance of the Entire Foot

PubMed Central

Wang, Yan; Li, Zengyong; Wong, Duo Wai-Chi; Zhang, Ming

2015-01-01

Background/Methodology Ankle arthrodesis is one popular surgical treatment for ankle arthritis, chronic instability, and degenerative deformity. However, complications such as foot pain, joint arthritis, and bone fracture may cause patients to suffer other problems. Understanding the internal biomechanics of the foot is critical for assessing the effectiveness of ankle arthrodesis and provides a baseline for the surgical plan. This study aimed to understand the biomechanical effects of ankle arthrodesis on the entire foot and ankle using finite element analyses. A three-dimensional finite element model of the foot and ankle, involving 28 bones, 103 ligaments, the plantar fascia, major muscle groups, and encapsulated soft tissue, was developed and validated. The biomechanical performances of a normal foot and a foot with ankle arthrodesis were compared at three gait instants, first-peak, mid-stance, and second-peak. Principal Findings/Conclusions Changes in plantar pressure distribution, joint contact pressure and forces, von Mises stress on bone and foot deformation were predicted. Compared with those in the normal foot, the peak plantar pressure was increased and the center of pressure moved anteriorly in the foot with ankle arthrodesis. The talonavicular joint and joints of the first to third rays in the hind- and mid-foot bore the majority of the loading and sustained substantially increased loading after ankle arthrodesis. An average contact pressure of 2.14 MPa was predicted at the talonavicular joint after surgery and the maximum variation was shown to be 80% in joints of the first ray. The contact force and pressure of the subtalar joint decreased after surgery, indicating that arthritis at this joint was not necessarily a consequence of ankle arthrodesis but rather a progression of pre-existing degenerative changes. Von Mises stress in the second and third metatarsal bones at the second-peak instant increased to 52 MPa and 34 MPa, respectively, after surgery. These variations can provide indications for outcome assessment of ankle arthrodesis surgery. PMID:26222188

Effects of Ankle Arthrodesis on Biomechanical Performance of the Entire Foot.

PubMed

Wang, Yan; Li, Zengyong; Wong, Duo Wai-Chi; Zhang, Ming

2015-01-01

Ankle arthrodesis is one popular surgical treatment for ankle arthritis, chronic instability, and degenerative deformity. However, complications such as foot pain, joint arthritis, and bone fracture may cause patients to suffer other problems. Understanding the internal biomechanics of the foot is critical for assessing the effectiveness of ankle arthrodesis and provides a baseline for the surgical plan. This study aimed to understand the biomechanical effects of ankle arthrodesis on the entire foot and ankle using finite element analyses. A three-dimensional finite element model of the foot and ankle, involving 28 bones, 103 ligaments, the plantar fascia, major muscle groups, and encapsulated soft tissue, was developed and validated. The biomechanical performances of a normal foot and a foot with ankle arthrodesis were compared at three gait instants, first-peak, mid-stance, and second-peak. Changes in plantar pressure distribution, joint contact pressure and forces, von Mises stress on bone and foot deformation were predicted. Compared with those in the normal foot, the peak plantar pressure was increased and the center of pressure moved anteriorly in the foot with ankle arthrodesis. The talonavicular joint and joints of the first to third rays in the hind- and mid-foot bore the majority of the loading and sustained substantially increased loading after ankle arthrodesis. An average contact pressure of 2.14 MPa was predicted at the talonavicular joint after surgery and the maximum variation was shown to be 80% in joints of the first ray. The contact force and pressure of the subtalar joint decreased after surgery, indicating that arthritis at this joint was not necessarily a consequence of ankle arthrodesis but rather a progression of pre-existing degenerative changes. Von Mises stress in the second and third metatarsal bones at the second-peak instant increased to 52 MPa and 34 MPa, respectively, after surgery. These variations can provide indications for outcome assessment of ankle arthrodesis surgery.

Effortful Pitch Glide: A Potential New Exercise Evaluated by Dynamic MRI

ERIC Educational Resources Information Center

Miloro, Keri Vasquez; Pearson, William G., Jr.; Langmore, Susan E.

2014-01-01

Purpose: The purpose of this study was to compare the biomechanics of the effortful pitch glide (EPG) with swallowing using dynamic MRI. The EPG is a combination of a pitch glide and a pharyngeal squeeze maneuver for targeting laryngeal and pharyngeal muscles. The authors hypothesized that the EPG would elicit significantly greater structural…

Applications of biomechanics for prevention of work-related musculoskeletal disorders.

PubMed

Garg, Arun; Kapellusch, Jay M

2009-01-01

This paper summarises applications of biomechanical principles and models in industry to control musculoskeletal disorders of the low back and upper extremity. Applications of 2-D and 3-D biomechanical models to estimate compressive force on the low back, the strength requirements of jobs, application of guidelines for overhead work and application of strain index and threshold limit value to address distal upper extremity musculoskeletal disorders are presented. Several case studies applied in the railroad industry, manufacturing, healthcare and warehousing are presented. Finally, future developments needed for improved biomechanical applications in industry are discussed. The information presented will be of value to practising ergonomists to recognise how biomechanics has played a significant role in identifying causes of musculoskeletal disorders and controlling them in the workplace. In particular, the information presented will help practising ergonomists with how physical stresses can be objectively quantified.

Vocal fold proteoglycans and their influence on biomechanics.

PubMed

Gray, S D; Titze, I R; Chan, R; Hammond, T H

1999-06-01

To examine the interstitial proteins of the vocal fold and their influence on the biomechanical properties of that tissue. Anatomic study of the lamina propria of human cadaveric vocal folds combined with some viscosity testing. Identification of proteoglycans is performed with histochemical staining. Quantitative analysis is performed using an image analysis system. A rheometer is used for viscosity testing. Three-dimensional rendering program is used for the computer images. Proteoglycans play an important role in tissue biomechanics. Hyaluronic acid is a key molecule that affects viscosity. The proteoglycans of the lamina propria have important biological and biomechanical effects. The role of hyaluronic acid in determining tissue viscosity is emphasized. Viscosity, its effect on phonatory threshold pressure and energy expended due to phonation is discussed. Proteoglycans, particularly hyaluronic acid, play important roles in determining biomechanical properties of tissue oscillation. Future research will likely make these proteins of important therapeutic interest.

The effect of sodium hypochlorite and ginger extract on microorganisms and endotoxins in endodontic treatment of infected root canals.

PubMed

Valera, Marcia Carneiro; Maekawa, Lilian Eiko; Chung, Adriana; Cardoso, Flavia Goulart Rosa; Oliveira, Luciane Dias de; Oliveira, Carolina Lima de; Carvalho, Claudio Antonio Talge

2014-01-01

This in vitro study sought to evaluate the biomechanical preparation action on microorganisms and endotoxins by using sodium hypochlorite (NaOCl) and an intracanal medication containing Zingiber officinale, with or without calcium hydroxide. Single-rooted teeth were contaminated, and root canal instrumentation (using 2.5% NaOCl) was performed. Samples were divided into 4 groups, according to the intracanal medication employed. The root canal content was gathered 28 days after contamination (baseline), immediately after biomechanical preparation, 7 days after biomechanical preparation, 14 days after intracanal medication, and 7 days after intracanal medication was removed. The results (submitted to Kruskal-Wallis and Dunn tests) showed that the NaOCl eliminated 100% of root canal microorganisms and reduced 88.8% of endotoxins immediately after biomechanical preparation, and 83.2% at 7 days after biomechanical preparation.

High-Tensile Strength Tape Versus High-Tensile Strength Suture: A Biomechanical Study.

PubMed

Gnandt, Ryan J; Smith, Jennifer L; Nguyen-Ta, Kim; McDonald, Lucas; LeClere, Lance E

2016-02-01

To determine which suture design, high-tensile strength tape or high-tensile strength suture, performed better at securing human tissue across 4 selected suture techniques commonly used in tendinous repair, by comparing the total load at failure measured during a fixed-rate longitudinal single load to failure using a biomechanical testing machine. Matched sets of tendon specimens with bony attachments were dissected from 15 human cadaveric lower extremities in a manner allowing for direct comparison testing. With the use of selected techniques (simple Mason-Allen in the patellar tendon specimens, whip stitch in the quadriceps tendon specimens, and Krackow stitch in the Achilles tendon specimens), 1 sample of each set was sutured with a 2-mm braided, nonabsorbable, high-tensile strength tape and the other with a No. 2 braided, nonabsorbable, high-tensile strength suture. A total of 120 specimens were tested. Each model was loaded to failure at a fixed longitudinal traction rate of 100 mm/min. The maximum load and failure method were recorded. In the whip stitch and the Krackow-stitch models, the high-tensile strength tape had a significantly greater mean load at failure with a difference of 181 N (P = .001) and 94 N (P = .015) respectively. No significant difference was found in the Mason-Allen and simple stitch models. Pull-through remained the most common method of failure at an overall rate of 56.7% (suture = 55%; tape = 58.3%). In biomechanical testing during a single load to failure, high-tensile strength tape performs more favorably than high-tensile strength suture, with a greater mean load to failure, in both the whip- and Krackow-stitch models. Although suture pull-through remains the most common method of failure, high-tensile strength tape requires a significantly greater load to pull-through in a whip-stitch and Krakow-stitch model. The biomechanical data obtained in the current study indicates that high-tensile strength tape may provide better repair strength compared with high-tensile strength suture at time-zero simulated testing. Published by Elsevier Inc.

The Influence of Artificial Cervical Disc Prosthesis Height on the Cervical Biomechanics: A Finite Element Study.

PubMed

Yuan, Wei; Zhang, Haiping; Zhou, Xiaoshu; Wu, Weidong; Zhu, Yue

2018-05-01

Artificial cervical disc replacement is expected to maintain normal cervical biomechanics. At present, the effect of the Prestige LP prosthesis height on cervical biomechanics has not been thoroughly studied. This finite element study of the cervical biomechanics aims to predict how the parameters, like range of motion (ROM), adjacent intradiscal pressure, facet joint force, and bone-implant interface stress, are affected by different heights of Prestige LP prostheses. The finite element model of intact cervical spine (C3-C7) was obtained from our previous study, and the model was altered to implant Prestige LP prostheses at the C5-C6 level. The effects of the height of 5, 6, and 7 mm prosthesis replacement on ROM, adjacent intradiscal pressure, facet joint force, as well as the distribution of bone-implant interface stress were examined. ROM, adjacent intradiscal pressure, and facet joint force increased with the prosthesis height, whereas ROM and facet joint force decreased at C5-C6. The maximal stress on the inferior surface of the prostheses was greater than that on the superior surface, and the stresses increased with the prosthesis height. The biomechanical changes were slightly affected by the height of 5 and 6 mm prostheses, but were strongly affected by the 7-mm prosthesis. An appropriate height of the Prestige LP prosthesis can preserve normal ROM, adjacent intradiscal pressure, and facet joint force. Prostheses with a height of ≥2 mm than normal can lead to marked changes in the cervical biomechanics and bone-implant interface stress. Copyright © 2018 Elsevier Inc. All rights reserved.

Biomechanics Associated with Patellofemoral Pain and ACL Injuries in Sports.

PubMed

Weiss, Kaitlyn; Whatman, Chris

2015-09-01

Knee injuries are prevalent among a variety of competitive sports and can impact an athlete's ability to continue to participate in their sport or, in the worst case, end an athlete's career. The aim was to evaluate biomechanics associated with both patellofemoral pain syndrome (PFPS) and anterior cruciate ligament (ACL) injuries (in sports involving landing, change in direction, or rapid deceleration) across the three time points frequently reported in the literature: pre-injury, at the time of injury, and following injury. A search of the literature was conducted for research evaluating biomechanics associated with ACL injury and PFPS. The Web of Science, SPORTDiscus, EBSCO, PubMed, and CINAHL databases, to March 2015, were searched, and journal articles focused on ACL injuries and PFPS in sports that met the inclusion criteria were reviewed. The search methodology was created with the intent of extracting case-control, case, and cohort studies of knee injury in athletic populations. The search strategy was restricted to only full-text articles published in English. These articles were included in the review if they met all of the required selection criteria. The following inclusion criteria were used: (1) The study must report lower extremity biomechanics in one of the following settings: (a) a comparison of currently injured and uninjured participants, (b) a prospective study evaluating risk factors for injury, or (c) a study reporting on the injury event itself. (2) The study must include only currently active participants who were similar at baseline (i.e. healthy, high school level basketball players currently in-season) and include biomechanical analysis of either landing, change in direction, or rapid deceleration. (3) The study must include currently injured participants. The studies were graded on the basis of quality, which served as an indication of risk of bias. An adapted version of the 'Strengthening the Reporting of Observational Studies in Epidemiology' (STROBE) guidelines was used to rate observational research. Fifteen journal articles focusing on ACL injuries and PFPS in sports met the inclusion criteria. These included three associated with both ACL injuries and PFPS across multiple time points. There was limited evidence for an association between ankle biomechanics and knee injury, with only one ACL injury study identifying decreased plantar flexion in association with injury. Only prospective studies can determine biomechanical risk factors associated with ACL injuries and PFPS. Case studies and case-control studies do not allow for the determination of risk factors associated with both ACL injuries and PFPS as there is no certainty regarding the presence of the observed biomechanics prior to the onset of injury. Further, each study design has its own set of limitations. Lastly, the majority of the studies included in this review had adult female participants. By evaluating several different study designs looking at knee injuries during high-risk manoeuvres, we were able to obtain a holistic perspective of biomechanics associated with PFPS and ACL injuries. Looking at different biomechanical research approaches allowed us to assess not only the mechanism of injury, but also to look for commonalities in biomechanics (in particular, altered frontal plane mechanics at the knee and altered sagittal plane mechanics at the knee and hip) between injured and uninjured participants pre-injury, at the time of injury, and following injury, to better understand potential causes of PFPS and ACL injury. Development of injury prevention programmes should focus on correcting these mechanics observed across the three time points during high-risk manoeuvres as this may help decrease the prevalence of ACL injury and PFPS. Programmes focusing not only on neuromuscular training, but also skill-specific training focused on correcting mechanics during these high-risk manoeuvres may be of greatest benefit regarding prevention. Future research should consider the impact of cumulative loading on knee injury risk. Additionally, better techniques for assessing mechanics in-game are needed in order to facilitate injury prevention and screening strategies.

Biomechanical comparisons of single- and double-legged drop jumps with changes in drop height.

PubMed

Wang, L-I; Peng, H-T

2014-06-01

The purpose of this study was to compare the biomechanics of single- and double-legged drop jumps (SDJ vs. DDJ) with changes in drop height. Jumping height, ground contact time, reactive strength index, ground reaction force, loading rate of ground reaction force, joint power and stiffness were measured in 12 male college students during SDJ from 20-, 30-, 40-, and 50-cm heights and DDJ from of 20- and 40-cm heights. The peak impact force was increased with the incremental drop height during SDJs. The jumping height and leg and ankle stiffness of SDJ30 were greater than those of SDJ40 and SDJ50. The knee and hip stiffnesses of SDJ30 were greater than those of SDJ50. The impact forces of SDJ30-50 were greater than those of DDJ40. The leg, ankle, knee and hip joint stiffnesses of SDJ20-30 were greater than those of DDJ20 and DDJ40. The propulsive forces of SDJ20-50 were greater than those of DDJ20 and DDJ40. The jumping height of SDJ30 was greater than that of DDJ20. Drop height of 30 cm was recommended during single-legged drop jump with the best biomechanical benefit. Single-legged drop jump from 20-30 cm could provide comparable intensity to double-legged drop jump from 40 cm. © Georg Thieme Verlag KG Stuttgart · New York.

Ablation depth and its effects on corneal biomechanical changes in laser in situ keratomileusis and epipolis laser in situ keratomileusis.

PubMed

Zhang, Lin; Wang, Yan; Yang, Xiaoyan

2014-04-01

To assess the corneal biomechanical parameters prior to and following laser in situ keratomileusis (LASIK) and epipolis laser in situ keratomileusis (epi-LASIK) and evaluate the probable correlative factors. Corneal hysteresis (CH), corneal resistance factor (CRF) and other biomechanical metrics were measured and evaluated with an ocular response analyzer preoperatively and 1 month postoperatively. Compared with preoperative values, CH and CRF decreased significantly after surgery in both groups (P = 0.000). The LASIK group exhibited a positive correlation between ablation depth (AD) and ∆CH/∆CRF with a strong r value (r = 0.543, P = 0.000; r = 0.574, P = 0.000). In the epi-LASIK group, however, the correlation was much weaker (r = -0.090, P = 0.682; r = 0.093, P = 0.673), although there were no significant differences between LASIK and epi-LASIK groups in postoperative CH (P = 0.730) and CRF (P = 0.736), and in the changes between CH (P = 0.539) and CRF (P = 0.881). Corneal biomechanical changes correlated with AD in LASIK but not in epi-LASIK, and it appeared that patients with identical demographics and similar attempted corrections are more likely to face a greater danger when undergoing LASIK than epi-LASIK. Therefore, the surface ablation procedure was recommended instead of lamellar ablation especially for correcting high myopia from a biomechanical viewpoint.

Surface-based prostate registration with biomechanical regularization

NASA Astrophysics Data System (ADS)

van de Ven, Wendy J. M.; Hu, Yipeng; Barentsz, Jelle O.; Karssemeijer, Nico; Barratt, Dean; Huisman, Henkjan J.

2013-03-01

Adding MR-derived information to standard transrectal ultrasound (TRUS) images for guiding prostate biopsy is of substantial clinical interest. A tumor visible on MR images can be projected on ultrasound by using MRUS registration. A common approach is to use surface-based registration. We hypothesize that biomechanical modeling will better control deformation inside the prostate than a regular surface-based registration method. We developed a novel method by extending a surface-based registration with finite element (FE) simulation to better predict internal deformation of the prostate. For each of six patients, a tetrahedral mesh was constructed from the manual prostate segmentation. Next, the internal prostate deformation was simulated using the derived radial surface displacement as boundary condition. The deformation field within the gland was calculated using the predicted FE node displacements and thin-plate spline interpolation. We tested our method on MR guided MR biopsy imaging data, as landmarks can easily be identified on MR images. For evaluation of the registration accuracy we used 45 anatomical landmarks located in all regions of the prostate. Our results show that the median target registration error of a surface-based registration with biomechanical regularization is 1.88 mm, which is significantly different from 2.61 mm without biomechanical regularization. We can conclude that biomechanical FE modeling has the potential to improve the accuracy of multimodal prostate registration when comparing it to regular surface-based registration.

The fixation strength of tibial PCL press-fit reconstructions.

PubMed

Ettinger, M; Wehrhahn, T; Petri, M; Liodakis, E; Olender, G; Albrecht, U-V; Hurschler, C; Krettek, C; Jagodzinski, M

2012-02-01

A secure tibial press-fit technique in posterior cruciate ligament reconstructions is an interesting technique because no hardware is necessary. For anterior cruciate ligament (ACL) reconstruction, a few press-fit procedures have been published. Up to the present point, no biomechanical data exist for a tibial press-fit posterior cruciate ligament (PCL) reconstruction. The purpose of this study was to characterize a press-fit procedure for PCL reconstruction that is biomechanically equivalent to an interference screw fixation. Quadriceps and hamstring tendons of 20 human cadavers (age: 49.2 ± 18.5 years) were used. A press-fit fixation with a knot in the semitendinosus tendon (K) and a quadriceps tendon bone block graft (Q) were compared to an interference screw fixation (I) in 30 porcine femora. In each group, nine constructs were cyclically stretched and then loaded until failure. Maximum load to failure, stiffness, and elongation during failure testing and cyclical loading were investigated. The maximum load to failure was 518 ± 157 N (387-650 N) for the (K) group, 558 ± 119 N (466-650 N) for the (I) group, and 620 ± 102 N (541-699 N) for the (Q) group. The stiffness was 55 ± 27 N/mm (18-89 N/mm) for the (K) group, 117 ± 62 N/mm (69-165 N/mm) for the (I) group, and 65 ± 21 N/mm (49-82 N/mm) for the (Q) group. The stiffness of the (I) group was significantly larger (P = 0.01). The elongation during cyclical loading was significantly larger for all groups from the 1st to the 5th cycle compared to the elongation in between the 5th to the 20th cycle (P < 0.03). All techniques exhibited larger elongation during initial loading. Load to failure and stiffness was significantly different between the fixations. The Q fixation showed equal biomechanical properties compared to a pure tendon fixation (I) with an interference screw. All three fixation techniques that were investigated exhibit comparable biomechanical properties. Preconditioning of the constructs is critical. Clinical trials have to investigate the biological effectiveness of these fixation techniques.

Clinical outcomes and frontal plane two-dimensional biomechanics during the 30-second single leg stance test in patients before and after hip abductor tendon reconstructive surgery.

PubMed

Huxtable, Rose E; Ackland, Timothy R; Janes, Gregory C; Ebert, Jay R

2017-07-01

Hip abductor tendon tears are a common cause of Greater Trochanteric Pain Syndrome. Conservative treatments are often ineffective and surgical reconstruction may be recommended. This study investigated the improvement in clinical outcomes and frontal plane two-dimensional biomechanics during a 30-second single leg stance test, in patients undergoing reconstruction. We hypothesized that clinical scores and pertinent biomechanical variables would significantly improve post-surgery, and these outcomes would be significantly correlated. Twenty-one patients with symptomatic tendon tears underwent reconstruction. Patients were evaluated pre-surgery, and at 6 and 12months post-surgery, using patient-reported outcome measures, assessment of hip abductor strength and six-minute walk capacity. Frontal plane, two-dimensional, biomechanical variables including pelvis-on-femur angle, pelvic drop, trunk lean and lateral pelvic shift, were evaluated throughout a 30-second single leg stance test. ANOVA evaluated outcomes over time, while Pearson's correlations investigated associations between clinical scores, pain, functional and biomechanical outcome variables. While clinical and functional measures significantly improved (P<0.05) over time, no significant group differences (P>0.05) were observed in biomechanical variables from pre- to post-surgery. While five patients displayed a positive Trendelenburg sign pre-surgery, only one was positive post-surgery. Clinical outcomes and biomechanical variables during the single leg stance test were not correlated. Despite improvements in clinical and functional measures over time, biomechanical changes during a weight bearing single leg stance test were not significantly different following tendon repair. Follow up beyond 12months may be required, whereby symptomatic relief may precede functional and biomechanical improvement. Copyright © 2017 Elsevier Ltd. All rights reserved.

The use of a magnesium-based bone adhesive for flexor tendon-to-bone healing

PubMed Central

Stavros, Thomopoulos; Emmanouil, Zampiakis; Rosalina, Das; Hyun-Min, Kim; J., Silva, Matthew; Necat, Havlioglu; H., Gelberman, Richard

2010-01-01

Purpose Our previous studies in a canine animal model demonstrated that the flexor tendon-to-bone insertion site has a poor capacity to heal. Magnesium based adhesives have the potential to improve tendon-to-bone healing. Therefore, we hypothesized that magnesium based bone adhesive (MBA) will improve the tendon-to-bone biomechanical properties initially and in the early period after repair. Methods Flexor digitorum profundus tendons were injured and repaired into bone tunnels in the distal phalanges of dogs. The bone tunnels were either filled with MBA prior to completing the repair or left empty (CTL). Histologic appearance, tensile properties, range of motion, and bone density were examined at time zero and 21 days after the repair. Results There was no histologic evidence of acute inflammation. There appeared to be more mast cells in the MBA group than in the CTL group. Chronic inflammatory infiltrate and fibrosis was slightly higher in the MBA group compared to the CTL group. Tensile properties at time zero were significantly higher in the MBA group compared to the CTL group. However, tensile properties were significantly lower in the MBA group compared to the CTL group at 21 days. Range of motion and bone density were significantly lower in the MBA and CTL groups compared to normal (i.e., uninjured) at 21 days; no differences were seen when comparing MBA to CTL. Conclusions We found that the initial biomechanical properties of flexor tendon-to-bone repairs can be improved with MBA. However, MBA use in vivo led to a decrease in the biomechanical properties of the repair. There was no effect of MBA on bone density or range of motion in the early period after repair. Our histologic analysis suggests that the poor healing in the MBA group may have been due to an allergic response or to increased chronic inflammation due to the foreign material. PMID:19643291

A comparison of biomechanical stability and pullout strength of two C1-C2 fixation constructs.

PubMed

Savage, Jason W; Limthongkul, Worawat; Park, Hyung-Soon; Zhang, Li-Qun; Karaikovic, Eldin E

2011-07-01

Several fusion techniques are used to treat atlantoaxial instability. Recent literature suggests that intralaminar screw (LS) fixation and pedicle screw (PS) fixation offer similar stability and comparable pullout strength. No studies have compared these characteristics after cyclic loading. To compare the stability and pullout strength of intra-LSs and PSs in a C1-C2 instability model after 1,000 cycles of axial loading. In vitro biomechanical study. Stability in axial rotation and screw pullout strength after cyclic loading. Six fresh-frozen human cadaveric cervical spines (C1-C2) were used in this study. C1-C2 instability was mimicked via odontoidotomy at its base and posterior soft-tissue release, including the supraspinous ligaments and facet joint capsules. Specimens were tested to 1,000 cycles after stabilization with two fixation constructs: C1 lateral mass (LM) screws and C2 intra-LSs (C1LM-C2LS) and C1 LM screws and C2 PSs (C1LM-C2PS). Angular motion was recorded for right and left axial rotation using an Optotrak 3020 system (Northern Digital, Waterloo, Ontario, Canada). Tensile loading to failure was then performed collinear to the longitudinal axis of the screw, and the data were recorded as peak pullout strength in newtons. There was no statistically significant difference in stability (measured in degrees of rotation) between the intra-LS and PS constructs at 250, 500, 750, and 1,000 cycles of axial rotation. Furthermore, there was no significant difference in stability at 250 cycles versus 1,000 cycles for the LS (1.30 vs. 1.49, p = .80) or PS (0.84 vs. 0.85, p = .96). Pedicle screws had higher pullout strength when compared with the intra-LSs (757.5 ± 239 vs. 583.4 ± 472 N); however, high standard deviation precluded statistical significance (p = .44). Our data suggest that a C1LM and C2LS construct has similar biomechanical stability when compared with a C1LM and C2PS construct after 1,000 cycles of axial rotation. Furthermore, PSs had higher pullout strength when compared with LSs; however, this result was not statistically significant. Copyright © 2011 Elsevier Inc. All rights reserved.

Biomechanical evaluation of implant-supported prosthesis with various tilting implant angles and bone types in atrophic maxilla: A finite element study.

PubMed

Gümrükçü, Zeynep; Korkmaz, Yavuz Tolga; Korkmaz, Fatih Mehmet

2017-07-01

The purpose of this study is to evaluate and compare bone stress that occurs as a result of using vertical implants with simultaneous sinus augmentation with bone stress generated from oblique implants without sinus augmentation in atrophic maxilla. Six, three-dimensional (3D) finite element (FE) models of atrophic maxilla were generated with SolidWorks software. The maxilla models were varied for two different bone types. Models 2a, 2b and 2c represent maxilla models with D2 bone type. Models 3a, 3b and 3c represent maxilla models with D3 bone type. Five implants were embedded in each model with different configurations for vertical implant insertion with sinus augmentation: Model 2a/Model 3a, 30° tilted insertion; Model 2b/Model 3b and 45° tilted insertion; Model 2c/Model 3c. A 150 N load was applied obliquely on the hybrid prosthesis. The maximum von Mises stress values were comparatively evaluated using color scales. The von Mises stress values predicted by the FE models were higher for all D3 bone models in both cortical and cancellous bone. For the vertical implant models, lower stress values were found in cortical bone. Tilting of the distal implants by 30° increased the stress in the cortical layer compared to vertical implant models. Tilting of the distal implant by 45° decreased the stress in the cortical bone compared to the 30° models, but higher stress values were detected in the 45° models compared to the vertical implant models. Augmentation should be the first treatment option in atrophic maxilla in terms of biomechanics. Tilted posterior implants can create higher stress values than vertical posterior implants. During tilting implant planning, the use of a 45° tilted implant results in better biomechanical performance in peri-implant bone than 30° tilted implant due to the decrease in cantilever length. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bionic ankle–foot prosthesis normalizes walking gait for persons with leg amputation

PubMed Central

Herr, Hugh M.; Grabowski, Alena M.

2012-01-01

Over time, leg prostheses have improved in design, but have been incapable of actively adapting to different walking velocities in a manner comparable to a biological limb. People with a leg amputation using such commercially available passive-elastic prostheses require significantly more metabolic energy to walk at the same velocities, prefer to walk slower and have abnormal biomechanics compared with non-amputees. A bionic prosthesis has been developed that emulates the function of a biological ankle during level-ground walking, specifically providing the net positive work required for a range of walking velocities. We compared metabolic energy costs, preferred velocities and biomechanical patterns of seven people with a unilateral transtibial amputation using the bionic prosthesis and using their own passive-elastic prosthesis to those of seven non-amputees during level-ground walking. Compared with using a passive-elastic prosthesis, using the bionic prosthesis decreased metabolic cost by 8 per cent, increased trailing prosthetic leg mechanical work by 57 per cent and decreased the leading biological leg mechanical work by 10 per cent, on average, across walking velocities of 0.75–1.75 m s−1 and increased preferred walking velocity by 23 per cent. Using the bionic prosthesis resulted in metabolic energy costs, preferred walking velocities and biomechanical patterns that were not significantly different from people without an amputation. PMID:21752817

Stabilizing potential of anterior, posterior, and circumferential fixation for multilevel cervical arthrodesis: an in vitro human cadaveric study of the operative and adjacent segment kinematics.

PubMed

Dmitriev, Anton E; Kuklo, Timothy R; Lehman, Ronald A; Rosner, Michael K

2007-03-15

This is an in vitro biomechanical study. The current investigation was performed to evaluate the stabilizing potential of anterior, posterior, and circumferential cervical fixation on operative and adjacent segment motion following 2 and 3-level reconstructions. Previous studies reported increases in adjacent level range of motion (ROM) and intradiscal pressure following single-level cervical arthrodesis; however, no studies have compared adjacent level effects following multilevel anterior versus posterior reconstructions. Ten human cadaveric cervical spines were biomechanically tested using an unconstrained spine simulator under axial rotation, flexion-extension, and lateral bending loading. After intact analysis, all specimens were sequentially instrumented from C3 to C5 with: (1) lateral mass fixation, (2) anterior cervical plate with interbody cages, and (3) combined anterior and posterior fixation. Following biomechanical analysis of 2-level constructs, fixation was extended to C6 and testing repeated. Full ROM was monitored at the operative and adjacent levels, and data normalized to the intact (100%). All reconstructive methods reduced operative level ROM relative to intact specimens under all loading methods (P < 0.05). However, circumferential fixation provided the greatest segmental stability among 2 and 3-level constructs (P < 0.05). Moreover, anterior cervical plate fixation was least efficient at stabilizing operative segments following C3-C6 arthrodesis (P < 0.05). Supradjacent ROM was increased for all treatment groups compared to normal data during flexion-extension testing (P < 0.05). Similar trends were observed under axial rotation and lateral bending loading. At the distal level, flexion-extension and axial rotation testing revealed comparable intergroup differences (P < 0.05), while lateral bending loading indicated greater ROM following 2-level circumferential fixation (P < 0.05). Results from our study revealed greater adjacent level motion following all 3 fixation types. No consistent significant intergroup differences in neighboring segment kinematics were detected among reconstructions. Circumferential fixation provided the greatest level of segmental stability without additional significant increase in adjacent level ROM.

Effects of hydrostatic pressure on leporine meniscus cell-seeded PLLA scaffolds.

PubMed

Gunja, Najmuddin J; Athanasiou, Kyriacos A

2010-03-01

Hydrostatic pressure (HP) is an important component of the loading environment of the knee joint. Studies with articular chondrocytes and TMJ disc fibrochondrocytes have identified certain benefits of HP for tissue engineering purposes. However, similar studies with meniscus cells are lacking. Thus, in this experiment, the effects of applying 10 MPa of HP at three different frequencies (0, 0.1, and 1 Hz) to leporine meniscus cell-seeded PLLA scaffolds were examined. HP was applied once every 3 days for 1 h for a period of 28 days. Constructs were analyzed for cellular, biochemical, and biomechanical properties. At t = 4 weeks, total collagen/scaffold was found to be significantly higher in the 10 MPa, 0 Hz group when compared with other groups. This despite the fact that the cell numbers/scaffold were found to be lower in all HP groups when compared with the culture control. Additionally, the total GAG/scaffold, instantaneous modulus, and relaxation modulus were significantly increased in the 10 MPa, 0 Hz group when compared with the culture control. In summary, this experiment provides evidence for the benefit of a 10 MPa, 0 Hz stimulus, on both biochemical and biomechanical aspects, for the purposes of meniscus tissue engineering using PLLA scaffolds. (c) 2009 Wiley Periodicals, Inc.

Weight-bearing asymmetries during Sit-To-Stand in patients with mild-to-moderate hip osteoarthritis.

PubMed

Eitzen, Ingrid; Fernandes, Linda; Nordsletten, Lars; Snyder-Mackler, Lynn; Risberg, May Arna

2014-02-01

The Sit-To-Stand (STS) transition is a mechanically demanding task that may pose particular challenges for individuals with lower limb osteoarthritis (OA). Biomechanical features of STS have been investigated in patients with OA, but not in patients with early stage hip OA. The purpose of this study was to explore inter-limb weight-bearing asymmetries (WBA) and selected kinematic and kinetic variables during STS in patients with mild-to-moderate hip OA compared with healthy controls. Twenty-one hip OA patients and 23 controls were included in the study. Sagittal and frontal plane kinematic and kinetic data were collected using an eight-camera motion analysis system synchronized with two force plates embedded in the floor. There were no distinctive biomechanical alterations in sagittal or frontal plane kinematics or kinetics, movement time, or time to reach peak ground reaction force (GRF) in hip OA patients compared with controls. However, the hip OA patients revealed a distinct pattern of WBA compared with the controls, in unloading their involved limb by 18.4% at peak GRF. These findings indicate that patients with early stage hip OA are not yet forced into a stereotypical movement strategy for STS; however, the observed pattern of WBA requires clinical attention. Copyright © 2013 Elsevier B.V. All rights reserved.

Biomechanical advantages of robot-assisted pedicle screw fixation in posterior lumbar interbody fusion compared with freehand technique in a prospective randomized controlled trial-perspective for patient-specific finite element analysis.

PubMed

Kim, Ho-Joong; Kang, Kyoung-Tak; Park, Sung-Cheol; Kwon, Oh-Hyo; Son, Juhyun; Chang, Bong-Soon; Lee, Choon-Ki; Yeom, Jin S; Lenke, Lawrence G

2017-05-01

There have been conflicting results on the surgical outcome of lumbar fusion surgery using two different techniques: robot-assisted pedicle screw fixation and conventional freehand technique. In addition, there have been no studies about the biomechanical issues between both techniques. This study aimed to investigate the biomechanical properties in terms of stress at adjacent segments using robot-assisted pedicle screw insertion technique (robot-assisted, minimally invasive posterior lumbar interbody fusion, Rom-PLIF) and freehand technique (conventional, freehand, open approach, posterior lumbar interbody fusion, Cop-PLIF) for instrumented lumbar fusion surgery. This is an additional post-hoc analysis for patient-specific finite element (FE) model. The sample is composed of patients with degenerative lumbar disease. Intradiscal pressure and facet contact force are the outcome measures. Patients were randomly assigned to undergo an instrumented PLIF procedure using a Rom-PLIF (37 patients) or a Cop-PLIF (41), respectively. Five patients in each group were selected using a simple random sampling method after operation, and 10 preoperative and postoperative lumbar spines were modeled from preoperative high-resolution computed tomography of 10 patients using the same method for a validated lumbar spine model. Under four pure moments of 7.5 Nm, the changes in intradiscal pressure and facet joint contact force at the proximal adjacent segment following fusion surgery were analyzed and compared with preoperative states. The representativeness of random samples was verified. Both groups showed significant increases in postoperative intradiscal pressure at the proximal adjacent segment under four moments, compared with the preoperative state. The Cop-PLIF models demonstrated significantly higher percent increments of intradiscal pressure at proximal adjacent segments under extension, lateral bending, and torsion moments than the Rom-PLIF models (p=.032, p=.008, and p=.016, respectively). Furthermore, the percent increment of facet contact force was significantly higher in the Cop-PLIF models under extension and torsion moments than in the Rom-PLIF models (p=.016 under both extension and torsion moments). The present study showed the clinical application of subject-specific FE analysis in the spine. Even though there was biomechanical superiority of the robot-assisted insertions in terms of alleviation of stress increments at adjacent segments after fusion, cautious interpretation is needed because of the small sample size. Copyright © 2016 Elsevier Inc. All rights reserved.

Lower limb biomechanics during running in individuals with achilles tendinopathy: a systematic review

PubMed Central

2011-01-01

Background Abnormal lower limb biomechanics is speculated to be a risk factor for Achilles tendinopathy. This study systematically reviewed the existing literature to identify, critique and summarise lower limb biomechanical factors associated with Achilles tendinopathy. Methods We searched electronic bibliographic databases (Medline, EMBASE, Current contents, CINAHL and SPORTDiscus) in November 2010. All prospective cohort and case-control studies that evaluated biomechanical factors (temporospatial parameters, lower limb kinematics, dynamic plantar pressures, kinetics [ground reaction forces and joint moments] and muscle activity) associated with mid-portion Achilles tendinopathy were included. Quality of included studies was evaluated using the Quality Index. The magnitude of differences (effect sizes) between cases and controls was calculated using Cohen's d (with 95% CIs). Results Nine studies were identified; two were prospective and the remaining seven case-control study designs. The quality of 9 identified studies was varied, with Quality Index scores ranging from 4 to 15 out of 17. All studies analysed running biomechanics. Cases displayed increased eversion range of motion of the rearfoot (d = 0.92 and 0.67 in two studies), reduced maximum lower leg abduction (d = -1.16), reduced ankle joint dorsiflexion velocity (d = -0.62) and reduced knee flexion during gait (d = -0.90). Cases also demonstrated a number of differences in dynamic plantar pressures (primarily the distribution of the centre of force), ground reaction forces (large effects for timing variables) and also showed reduced peak tibial external rotation moment (d = -1.29). Cases also displayed differences in the timing and amplitude of a number of lower limb muscles but many differences were equivocal. Conclusions There are differences in lower limb biomechanics between those with and without Achilles tendinopathy that may have implications for the prevention and management of the condition. However, the findings need to be interpreted with caution due to the limited quality of a number of the included studies. Future well-designed prospective studies are required to confirm these findings. PMID:21619710

Gluteal tendinopathy and hip osteoarthritis: Different pathologies, different hip biomechanics.

PubMed

Allison, Kim; Hall, Michelle; Hodges, Paul W; Wrigley, Tim V; Vicenzino, Bill; Pua, Yong-Hao; Metcalf, Ben; Grimaldi, Alison; Bennell, Kim L

2018-03-01

Gluteal tendinopathy (GT) and hip osteoarthritis (OA) are the most common causes of hip pain and associated disability in older adults. Pain and altered walking biomechanics are common to both conditions. This study aimed to compare three-dimensional walking biomechanics between individuals with unilateral, symptomatic GT and HOA. Sixty individuals with symptomatic unilateral GT confirmed by magnetic-resonance-imaging and 73 individuals with symptomatic unilateral HOA (Kellgren-Lawrence Grade ≥ 2) underwent three-dimensional gait analysis. Maximum and minimum values of the external sagittal hip moment, the first peak, second peak and mid-stance minimum of the hip adduction moment (HAM), sagittal plane hip excursion and hip joint angles, pelvic obliquity and trunk lean, at the three HAM time points during stance phase of walking were compared between groups. Compared to individuals with HOA, those with GT exhibited a greater hip peak extension moment (P < 0.001) and greater HAM throughout the stance phase of walking (P = 0.01-P < 0.001), greater hip adduction (P < 0.001) and internal rotation (P < 0.01-P < 0.001) angles and lower hip flexion angles and excursion (P = 0.02 - P < 0.001). Individuals with HOA exhibited a greater forward trunk lean (P ≤ 0.001) throughout stance, and greater ipsilateral trunk lean in the frontal plane (P < 0.001) than those with GT. Despite presence of pain in both conditions, hip kinematics and kinetics differ between individuals with symptomatic unilateral GT and those with symptomatic unilateral HOA. These condition-specific impairments may be targets for optimization of management of HOA and GT. Copyright © 2018 Elsevier B.V. All rights reserved.

Biomechanical Performance of Medial Row Suture Placement Relative to the Musculotendinous Junction in Transosseous Equivalent Suture Bridge Double-Row Rotator Cuff Repair.

PubMed

Virk, Mandeep S; Bruce, Benjamin; Hussey, Kristen E; Thomas, Jacqueline M; Luthringer, Tyler A; Shewman, Elizabeth F; Wang, Vincent M; Verma, Nikhil N; Romeo, Anthony A; Cole, Brian J

2017-02-01

To compare the biomechanical performance of medial row suture placement relative to the musculotendinous junction (MTJ) in a cadaveric transosseous equivalent suture bridge (TOE-SB) double-row (DR) rotator cuff repair (RCR) model. A TOE-SB DR technique was used to reattach experimentally created supraspinatus tendon tears in 9 pairs of human cadaveric shoulders. The medial row sutures were passed either near the MTJ (MTJ group) or 10 mm lateral to the MTJ (rotator cuff tendon [RCT] group). After the supraspinatus repair, the specimens underwent cyclic loading and load to failure tests. The localized displacement of the markers affixed to the tendon surface was measured with an optical tracking system. The MTJ group showed a significantly higher (P = .03) medial row failure (5/9; 3 during cyclic testing and 2 during load to failure testing) compared with the RCT group (0/9). The mean number of cycles completed during cyclic testing was lower in the MTJ group (77) compared with the RCT group (100; P = .07) because 3 specimens failed in the MTJ group during cyclic loading. There were no significant differences between the 2 study groups with respect to biomechanical properties during the load to failure testing. In a cadaveric TOE-SB DR RCR model, medial row sutures through the MTJ results in a significantly higher rate of medial row failure. In rotator cuff tears with tendon tissue loss, passage of medial row sutures through the MTJ should be avoided in a TOE-SB RCR technique because of the risk of medial row failure. Copyright © 2016. Published by Elsevier Inc.

An antiaging skin care system containing alpha hydroxy acids and vitamins improves the biomechanical parameters of facial skin

PubMed Central

Tran, Diana; Townley, Joshua P; Barnes, Tanya M; Greive, Kerryn A

2015-01-01

Background The demand for antiaging products has dramatically increased in recent years, driven by an aging population seeking to maintain the appearance of youth. This study investigates the effects of an antiaging skin care system containing alpha hydroxy acids (AHAs) in conjunction with vitamins B3, C, and E on the biomechanical parameters of facial skin. Methods Fifty two volunteers followed an antiaging skin care regimen comprising of cleanser, eye cream, day moisturizer, and night moisturizer for 21 days. Wrinkle depth (Ry) and skin roughness (Ra) were measured by skin surface profilometry of the crow’s feet area, and skin elasticity parameters R2 (gross elasticity), R5 (net elasticity), R6 (viscoelastic portion), and R7 (recovery after deformation) were determined for facial skin by cutometer, preapplication and after 7, 14, and 21 days. Volunteers also completed a self-assessment questionnaire. Results Compared to baseline, Ry and Ra significantly improved by 32.5% (P<0.0001) and 42.9% (P<0.0001), respectively, after 21 days of antiaging skin care treatment. These results were observed by the volunteers with 9 out of 10 discerning an improvement in skin texture and smoothness. Compared to baseline, R2 and R5 significantly increased by 15.2% (P<0.0001) and 12.5% (P=0.0449), respectively, while R6 significantly decreased by 17.7% (P<0.0001) after 21 days. R7 increased by 9.7% after 21 days compared to baseline but this was not significant over this time period. Conclusion An antiaging skin care system containing AHAs and vitamins significantly improves the biomechanical parameters of the skin including wrinkles and skin texture, as well as elasticity without significant adverse effects. PMID:25552908

An antiaging skin care system containing alpha hydroxy acids and vitamins improves the biomechanical parameters of facial skin.

PubMed

Tran, Diana; Townley, Joshua P; Barnes, Tanya M; Greive, Kerryn A

2015-01-01

The demand for antiaging products has dramatically increased in recent years, driven by an aging population seeking to maintain the appearance of youth. This study investigates the effects of an antiaging skin care system containing alpha hydroxy acids (AHAs) in conjunction with vitamins B3, C, and E on the biomechanical parameters of facial skin. Fifty two volunteers followed an antiaging skin care regimen comprising of cleanser, eye cream, day moisturizer, and night moisturizer for 21 days. Wrinkle depth (Ry ) and skin roughness (Ra ) were measured by skin surface profilometry of the crow's feet area, and skin elasticity parameters R2 (gross elasticity), R5 (net elasticity), R6 (viscoelastic portion), and R7 (recovery after deformation) were determined for facial skin by cutometer, preapplication and after 7, 14, and 21 days. Volunteers also completed a self-assessment questionnaire. Compared to baseline, Ry and Ra significantly improved by 32.5% (P<0.0001) and 42.9% (P<0.0001), respectively, after 21 days of antiaging skin care treatment. These results were observed by the volunteers with 9 out of 10 discerning an improvement in skin texture and smoothness. Compared to baseline, R2 and R5 significantly increased by 15.2% (P<0.0001) and 12.5% (P=0.0449), respectively, while R6 significantly decreased by 17.7% (P<0.0001) after 21 days. R7 increased by 9.7% after 21 days compared to baseline but this was not significant over this time period. An antiaging skin care system containing AHAs and vitamins significantly improves the biomechanical parameters of the skin including wrinkles and skin texture, as well as elasticity without significant adverse effects.

Biomechanical evaluation of a simulated T-9 burst fracture of the thoracic spine with an intact rib cage.

PubMed

Perry, Tiffany G; Mageswaran, Prasath; Colbrunn, Robb W; Bonner, Tara F; Francis, Todd; McLain, Robert F

2014-09-01

Classic biomechanical models have used thoracic spines disarticulated from the rib cage, but the biomechanical influence of the rib cage on fracture biomechanics has not been investigated. The well-accepted construct for stabilizing midthoracic fractures is posterior instrumentation 3 levels above and 2 levels below the injury. Short-segment fixation failure in thoracolumbar burst fractures has led to kyphosis and implant failure when anterior column support is lacking. Whether shorter constructs are viable in the midthoracic spine is a point of controversy. The objective of this study was the biomechanical evaluation of a burst fracture at T-9 with an intact rib cage using different fixation constructs for stabilizing the spine. A total of 8 human cadaveric spines (C7-L1) with intact rib cages were used in this study. The range of motion (ROM) between T-8 and T-10 was the outcome measure. A robotic spine testing system was programmed to apply pure moment loads (± 5 Nm) in lateral bending, flexion-extension, and axial rotation to whole thoracic specimens. Intersegmental rotations were measured using an optoelectronic system. Flexibility tests were conducted on intact specimens, then sequentially after surgically induced fracture at T-9, and after each of 4 fixation construct patterns. The 4 construct patterns were sequentially tested in a nondestructive protocol, as follows: 1) 3 above/2 below (3A/2B); 2) 1 above/1 below (1A/1B); 3) 1 above/1 below with vertebral body augmentation (1A/1B w/VA); and 4) vertebral body augmentation with no posterior instrumentation (VA). A repeated-measures ANOVA was used to compare the segmental motion between T-8 and T-10 vertebrae. Mean ROM increased by 86%, 151%, and 31% after fracture in lateral bending, flexion-extension, and axial rotation, respectively. In lateral bending, there was significant reduction compared with intact controls for all 3 instrumented constructs: 3A/2B (-92%, p = 0.0004), 1A/1B (-63%, p = 0.0132), and 1A/1B w/VA (-66%, p = 0.0150). In flexion-extension, only the 3A/2B pattern showed a significant reduction (-90%, p = 0.011). In axial rotation, motion was significantly reduced for the 3 instrumented constructs: 3A/2B (-66%, p = 0.0001), 1A/1B (-53%, p = 0.0001), and 1A/1B w/VA (-51%, p = 0.0002). Between the 4 construct patterns, the 3 instrumented constructs (3A/2B, 1A/1B, and 1A/1B w/VA) showed comparable stability in all 3 motion planes. This study showed no significant difference in the stability of the 3 instrumented constructs tested when the rib cage is intact. Fractures that might appear more grossly unstable when tested in the disarticulated spine may be bolstered by the ribs. This may affect the extent of segmental spinal instrumentation needed to restore stability in some spine injuries. While these initial findings suggest that shorter constructs may adequately stabilize the spine in this fracture model, further study is needed before these results can be extrapolated to clinical application.

Biomechanical properties of crystalline lens as a function of intraocular pressure assessed noninvasively by optical coherence elastography

NASA Astrophysics Data System (ADS)

Wu, Chen; Aglyamov, Salavat R.; Liu, Chih-Hao; Han, Zhaolong; Singh, Manmohan; Larin, Kirill V.

2017-02-01

Many ocular diseases such as glaucoma and uveitis can lead to the elevation of intraocular pressure (IOP). Previous research implies a link between elevated IOP and lens disease. However, the relationship between IOP elevation and biomechanical properties of the crystalline lens has not been directly studied yet. In this work, we investigated the biomechanical properties of porcine lens as a function of IOP by acoustic radiation force optical coherence elastography.

Elastin density: Link between histological and biomechanical properties of vaginal tissue in women with pelvic organ prolapse?

PubMed

de Landsheere, Laurent; Brieu, Mathias; Blacher, Silvia; Munaut, Carine; Nusgens, Betty; Rubod, Chrystèle; Noel, Agnès; Foidart, Jean-Michel; Nisolle, Michelle; Cosson, Michel

2016-04-01

The aim of the study was to correlate histological and biomechanical characteristics of the vaginal wall in women with pelvic organ prolapse (POP). Tissue samples were collected from the anterior [point Ba; POP Questionnaire (POP-Q)] and/or posterior (point Bp; POP-Q) vaginal wall of 15 women who underwent vaginal surgery for POP. Both histological and biomechanical assessments were performed from the same tissue samples in 14 of 15 patients. For histological assessment, the density of collagen and elastin fibers was determined by combining high-resolution virtual imaging and computer-assisted digital image analysis. For biomechanical testing, uniaxial tension tests were performed to evaluate vaginal tissue stiffness at low (C0) and high (C1) deformation rates. Biomechanical testing highlights the hyperelastic behavior of the vaginal wall. At low strains (C0), vaginal tissue appeared stiffer when elastin density was low. We found a statistically significant inverse relationship between C0 and the elastin/collagen ratio (p = 0.048) in the lamina propria. However, at large strain levels (C1), no clear relationship was observed between elastin density or elastin/collagen ratio and stiffness, likely reflecting the large dispersion of the mechanical behavior of the tissue samples. Histological and biomechanical properties of the vaginal wall vary from patient to patient. This study suggests that elastin density deserves consideration as a relevant factor of vaginal stiffness in women with POP.

Instrumentation Strategies to Reduce the Risks of Proximal Junctional Kyphosis in Adult Scoliosis: A Detailed Biomechanical Analysis.

PubMed

Aubin, Carl-Eric; Cammarata, Marco; Wang, Xiaoyu; Mac-Thiong, Jean-Marc

2015-05-01

Biomechanical analysis of proximal junctional kyphosis (PJK) through numerical simulations. Assessment of the effect of sagittal alignment, the upper instrumented vertebral level (UIV), and 4 other surgical variables on biomechanical indices related to the PJK risks. Despite retrospective clinical studies, biomechanical analysis of individual parameters associated with PJK is lacking to support instrumentation strategies to reduce the PJK risks. Instrumentations of 6 adult scoliosis cases with different operative strategies were simulated (1,152 simulations). Proximal junctional (PJ) angle and flexion loads were evaluated against the sagittal alignment and the proximal instrumentation level. Instrumenting 1 more proximal vertebra allowed the PJ angle, proximal moment, and force to be reduced by 18%, 25%, and 16%, respectively. Shifting sagittal alignment by 20 mm posteriorly increased the PJ angle and proximal moment by 16% and 22%, and increased the equivalent posterior extensor force by 37%. Bilateral complete facetectomy, posterior ligaments resection, and the combination of the 2 resulted in an increase of the PJ angle (by 10%, 28%, and 53%, respectively), flexion forces (by 4%, 12%, and 22%, respectively), and proximal moments (by 16%, 44%, and 83%, respectively). Transverse process hooks at UIV compared with pedicle screws allowed 26% lower PJ angle and flexion loads. The use of proximal transition rods with proximal diameter reduced from 5.5 to 4 mm slightly reduced PJ angle, flexion force, and moment (less than 8%). The increase in sagittal rod curvature from 10° to 40° increased the PJ angle (from 6% to 19%), flexion force (from 3% to 10%), and moment (from 9% to 27%). Simulated posteriorly shifted sagittal alignment was associated with higher PJK risks, whereas extending instrumentation proximally allowed a lower mechanical risk of PJK. Preserving PJ intervertebral elements and using a more flexible anchorage at UIV help reduce the biomechanical risks of PJK. Copyright © 2015 Scoliosis Research Society. Published by Elsevier Inc. All rights reserved.

Immediate effects of a new microprocessor-controlled prosthetic knee joint: a comparative biomechanical evaluation.

PubMed

Bellmann, Malte; Schmalz, Thomas; Ludwigs, Eva; Blumentritt, Siegmar

2012-03-01

To investigate the immediate biomechanical effects after transition to a new microprocessor-controlled prosthetic knee joint. Intervention cross-over study with repeated measures. Only prosthetic knee joints were changed. Motion analysis laboratory. Men (N=11; mean age ± SD, 36.7±10.2y; Medicare functional classification level, 3-4) with unilateral transfemoral amputation. Two microprocessor-controlled prosthetic knee joints: C-Leg and a new prosthetic knee joint, Genium. Static prosthetic alignment, time-distance parameters, kinematic and kinetic parameters, and center of pressure. After a half-day training and an additional half-day accommodation, improved biomechanical outcomes were demonstrated by the Genium: lower ground reaction forces at weight acceptance during level walking at various velocities, increased swing phase flexion angles during walking on a ramp, and level walking with small steps. Maximum knee flexion angle during swing phase at various velocities was nearly equal for Genium. Step-over-step stair ascent with the Genium knee was more physiologic as demonstrated by a more equal load distribution between the prosthetic and contralateral sides and a more natural gait pattern. When descending stairs and ramps, knee flexion moments with the Genium tended to increase. During quiet stance on a decline, subjects using Genium accepted higher loading of the prosthetic side knee joint, thus reducing same side hip joint loading as well as postural sway. In comparision to the C-Leg, the Genium demonstrated immediate biomechanical advantages during various daily ambulatory activities, which may lead to an increase in range and diversity of activity of people with above-knee amputations. Results showed that use of the Genium facilitated more natural gait biomechanics and load distribution throughout the affected and sound musculoskeletal structure. This was observed during quiet stance on a decline, walking on level ground, and walking up and down ramps and stairs. Copyright © 2012 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Effects of form-focused training on running biomechanics: A pilot randomized trial in untrained individuals

PubMed Central

Kumar, Deepak; McDermott, Kelly; Feng, Haojun; Goldman, Veronica; Luke, Anthony; Souza, Richard B; Hecht, Frederick M

2015-01-01

Objective To investigate the changes in running biomechanics after training in Form-Focused running using ChiRunning vs. Not-Form focused training and Self-Directed training in untrained individuals. Design Pilot study - Randomized controlled trial. Setting Research Institution with Tertiary Care Medical Center. Participants Seventeen subjects (9 males, 8 females) with pre-hypertension. Methods Twenty-two participants were randomized to three study arms but 17 completed the study. The study arms were: 1) group-based Form-Focused running using ChiRunning (enrolled, n =10; completed, n=7); 2) group-based conventional running (enrolled, n=6; completed, n=4); 3) self-directed training with educational materials (enrolled, n =6; completed, n=6). The training schedule was prescribed for 8 weeks with 4 weeks of follow-up. All subjects completed overground running motion analyses before and after training. Outcomes Ankle, knee, hip joint peak moments and powers; Average vertical loading rate (AVLR), impact peak, cadence, stride length, strike index, and stride reach. Paired T-tests were used to compare differences with-in groups over-time. Results Form-Focused group reduced their Stride Reach (P = .047) after the training but not the other groups. Form-Focused group showed a close to significant reduction in knee adduction moment (P = .051) and a reduction in the peak ankle eversion moment (P = .027). Self-Directed group showed an increase in the running speed, (P =.056) and increases in ankle and knee joint powers and moments. Conclusions There are differences in the changes in running biomechanics between individuals trained in running form that emphazies mid-foot strike, higher cadence, and shorter stride compared to those not trained in the thise technique. These differences may be associated with reduced lower extremity stress in individuals trained in this running form but future studies are needed to confirm these findings in larger samples. PMID:25633634

Triglycidylamine Crosslinking of Porcine Aortic Valve Cusps or Bovine Pericardium Results in Improved Biocompatibility, Biomechanics, and Calcification Resistance

PubMed Central

Connolly, Jeanne M.; Alferiev, Ivan; Clark-Gruel, Jocelyn N.; Eidelman, Naomi; Sacks, Michael; Palmatory, Elizabeth; Kronsteiner, Allyson; DeFelice, Suzanne; Xu, Jie; Ohri, Rachit; Narula, Navneet; Vyavahare, Narendra; Levy, Robert J.

2005-01-01

We investigated a novel polyepoxide crosslinker that was hypothesized to confer both material stabilization and calcification resistance when used to prepare bioprosthetic heart valves. Triglycidylamine (TGA) was synthesized via reacting epichlorhydrin and NH3. TGA was used to crosslink porcine aortic cusps, bovine pericardium, and type I collagen. Control materials were crosslinked with glutaraldehyde (Glut). TGA-pretreated materials had shrink temperatures comparable to Glut fixation. However, TGA crosslinking conferred significantly greater collagenase resistance than Glut pretreatment, and significantly improved biomechanical compliance. Sheep aortic valve interstitial cells grown on TGA-pretreated collagen did not calcify, whereas sheep aortic valve interstitial cells grown on control substrates calcified extensively. Rat subdermal implants (porcine aortic cusps/bovine pericardium) pretreated with TGA demonstrated significantly less calcification than Glut pretreated implants. Investigations of extracellular matrix proteins associated with calcification, matrix metalloproteinases (MMPs) 2 and 9, tenascin-C, and osteopontin, revealed that MMP-9 and tenascin-C demonstrated reduced expression both in vitro and in vivo with TGA crosslinking compared to controls, whereas osteopontin and MMP-2 expression were not affected. TGA pretreatment of heterograft biomaterials results in improved stability compared to Glut, confers biomechanical properties superior to Glut crosslinking, and demonstrates significant calcification resistance. PMID:15631995

Adaptations in single-leg hop biomechanics following anterior cruciate ligament reconstruction.

PubMed

Orishimo, Karl F; Kremenic, Ian J; Mullaney, Michael J; McHugh, Malachy P; Nicholas, Stephen J

2010-11-01

When a patient performs a clinically normal hop test based on distance, it cannot be assumed that the biomechanics are similar between limbs. The objective was to compare takeoff and landing biomechanics between legs in patients who have undergone anterior cruciate ligament reconstruction. Kinematics and ground reaction forces were recorded as 13 patients performed the single-leg hop on each leg. Distance hopped, joint range of motion, peak joint kinetics and the peak total extensor moment were compared between legs during both takeoff and landing. Average hop distance ratio (involved/noninvolved) was 93 ± 4%. Compared to the noninvolved side, knee motion during takeoff on the involved side was significantly reduced (P = 0.008). Peak moments and powers on the involved side were lower at the knee and higher at the ankle and hip compared with the noninvolved side (Side by Joint P = 0.011; P = 0.003, respectively). The peak total extensor moment was not different between legs (P = 0.305) despite a decrease in knee moment and increases in ankle and hip moments (Side by Joint P = 0.015). During landing, knee motion was reduced (P = 0.043), and peak power absorbed was decreased at the knee and hip and increased at the ankle on the involved side compared to the noninvolved side (P = 0.003). The compensations by other joints may indicate protective adaptations to avoid overloading the reconstructed knee.

The stabilizing potential of anterior, posterior and combined techniques for the reconstruction of a 2-level cervical corpectomy model: biomechanical study and first results of ATPS prototyping.

PubMed

Koller, Heiko; Schmidt, Rene; Mayer, Michael; Hitzl, Wolfgang; Zenner, Juliane; Midderhoff, Stefan; Middendorf, Stefan; Graf, Nicolaus; Gräf, Nicolaus; Resch, H; Wilke, Hans-Joachim; Willke, Hans-Joachim

2010-12-01

Clinical studies reported frequent failure with anterior instrumented multilevel cervical corpectomies. Hence, posterior augmentation was recommended but necessitates a second approach. Thus, an author group evaluated the feasibility, pull-out characteristics, and accuracy of anterior transpedicular screw (ATPS) fixation. Although first success with clinical application of ATPS has already been reported, no data exist on biomechanical characteristics of an ATPS-plate system enabling transpedicular end-level fixation in advanced instabilities. Therefore, we evaluated biomechanical qualities of an ATPS prototype C4-C7 for reduction of range of motion (ROM) and primary stability in a non-destructive setup among five constructs: anterior plate, posterior all-lateral mass screw construct, posterior construct with lateral mass screws C5 + C6 and end-level fixation using pedicle screws unilaterally or bilaterally, and a 360° construct. 12 human spines C3-T1 were divided into two groups. Four constructs were tested in group 1 and three in group 2; the ATPS prototypes were tested in both groups. Specimens were subjected to flexibility test in a spine motion tester at intact state and after 2-level corpectomy C5-C6 with subsequent reconstruction using a distractable cage and one of the osteosynthesis mentioned above. ROM in flexion-extension, axial rotation, and lateral bending was reported as normalized values. All instrumentations but the anterior plate showed significant reduction of ROM for all directions compared to the intact state. The 360° construct outperformed all others in terms of reducing ROM. While there were no significant differences between the 360° and posterior constructs in flexion-extension and lateral bending, the 360° constructs were significantly more stable in axial rotation. Concerning primary stability of ATPS prototypes, there were no significant differences compared to posterior-only constructs in flexion-extension and axial rotation. The 360° construct showed significant differences to the ATPS prototypes in flexion-extension, while no significant differences existed in axial rotation. But in lateral bending, the ATPS prototype and the anterior plate performed significantly worse than the posterior constructs. ATPS was shown to confer increased primary stability compared to the anterior plate in flexion-extension and axial rotation with the latter yielding significance. We showed that primary stability after 2-level corpectomy reconstruction using ATPS prototypes compared favorably to posterior systems and superior to anterior plates. From the biomechanical point, the 360° instrumentation was shown the most efficient for reconstruction of 2-level corpectomies. Further studies will elucidate whether fatigue testing will enhance the benefit of transpedicular anchorage with posterior constructs and ATPS.

Biomechanical analysis of cervical distraction.

PubMed

Miller, L S; Cotler, H B; De Lucia, F A; Cotler, J M; Hume, E L

1987-11-01

A biomechanical analysis of cervical distraction is presented, and a model comparing closed reduction of cervical spine dislocations to spring mechanics is developed. Behavior of a spring may be described as F = k delta x where F = distraction force; delta x = elongation of the spring; and k = spring constant. The records and roentgenograms of 24 cervical spine dislocations were reviewed retrospectively. Evaluation of cervical distraction vs traction weight indicates that Ftraction = kneck delta x; where F = traction weight and x = distraction at the injured level. The constant, kneck, is different for bilateral and unilateral dislocations (P less than .001) and is a function of magnitude of injury and neck morphology. As determined in this study, traction weight needed for reduction of facet dislocations may be estimated using the formulae: Ftx = 107.1 lbs/cm (x) unilateral, and Ftx = 76.4 lbs/cm (x) bilateral.

What to measure when determining orthotic needs in children with Down syndrome: a pilot study.

PubMed

Looper, Julia; Benjamin, Danielle; Nolan, Mindy; Schumm, Laura

2012-01-01

To compare the effects of off-the-shelf foot orthoses and supramalleolar orthoses on the gait of children with Down syndrome (DS), and establish criteria for determining orthoses prescription for a child with DS. We assessed the gait of 6 children (aged 4-7 years) with DS using the GAITRite system, and obtained height, weight, leg length, hypermobility, calcaneal eversion, navicular drop, and tibial torsion measurements. Supramalleolar orthoses lead to a longer cycle time than foot orthoses (P = .05) and barefoot walking (P = .03) and a lower cadence than barefoot walking (P = .04). Significant strong correlations with gait parameters were obtained for height, leg length, and hypermobility. Biomechanical measurements showed no significant correlations with gait parameters. The role of physical examination data, including anthropometric and biomechanical measurements in the prescription of orthoses requires further investigation.

Graft biomechanical properties after penetrating keratoplasty in keratoconus.

PubMed

Feizi, Sepehr; Einollahi, Bahram; Yazdani, Shahin; Hashemloo, Ali

2012-08-01

To measure corneal graft biomechanical properties after penetrating keratoplasty (PKP) in a group of keratoconic eyes using the ocular response analyzer (ORA) and to evaluate the relationship between donor size, donor-recipient disparity and central graft thickness (CGT), and ORA parameters. This cross-sectional study was conducted on 34 eyes of 34 keratoconus patients who had undergone PKP. Corneal hysteresis (CH), corneal resistance factor (CRF), and cornea-compensated intraocular pressure were measured at least 6 months after complete suture removal. Two groups of donor-recipient disparity (0.25 vs. 0.50 mm) were compared using the independent t test. Multivariate regression analysis was used to investigate the correlation of donor trephine size and CGT with ORA parameters. Factors influencing intraocular pressure measured with the Goldmann applanation tonometer (IOP GAT) after PKP were determined using multiple regression analysis. Mean patient age and follow-up period were 29.6 ± 6.2 years and 82.4 ± 59.6 months, respectively. Mean CGT, CH, and CRF were 564.7 ± 36.9 μm, 10.1 ± 2.1 mm Hg, and 10.0 ± 2.3 mm Hg, respectively. CH and CRF had a significant positive correlation with donor trephine size and CGT. Significantly greater values of CH and CRF were observed in the 0.5-mm disparity group compared with the 0.25-mm disparity group. Among the studied parameters, only CH, CRF, and cornea-compensated intraocular pressure had a significant positive correlation with IOP GAT. Graft biomechanics seem to be closer to normal values with larger grafts and greater donor-recipient disparity. These metrics had a significant correlation with IOP GAT after PKP.

Are allogenic or xenogenic screws and plates a reasonable alternative to alloplastic material for osteosynthesis--a histomorphological analysis in a dynamic system.

PubMed

Jacobsen, C; Obwegeser, J A

2010-12-01

Despite invention of titanium and resorbable screws and plates, still, one of the main challenges in bone fixation is the search for an ideal osteosynthetic material. Biomechanical properties, biocompatibility, and also cost effectiveness and clinical practicability are factors for the selection of a particular material. A promising alternative seems to be screws and plates made of bone. Recently, xenogenic bone pins and screws have been invented for use in joint surgery. In this study, screws made of allogenic sheep and xenogenic human bone were analyzed in a vital and dynamic sheep-model and compared to conventional titanium screws over a standard period of bone healing of 56 days with a constant applied extrusion force. Biomechanical analysis and histomorphological evaluation were performed. After 56 days of insertion xenogenic screws made of human bone showed significantly larger distance of extrusion of on average 173.8 μm compared to allogenic screws made of sheep bone of on average 27.8 and 29.95 μm of the titanium control group. Severe resorption processes with connective tissue interposition were found in the histomorphological analysis of the xenogenic screws in contrast to new bone formation and centripetal vascularization of the allogenic bone screw, as well as in processes of incorporation of the titanium control group. The study showed allogenic cortical bone screws as a substantial alternative to titanium screws with good biomechanical properties. In contrast to other reports a different result was shown for the xenogenic bone screws. They showed insufficient holding strength with confirmative histomorphological signs of degradation and insufficient osseointegration. Before common clinical use of xenogenic osteosynthetic material, further evaluation should be performed. Copyright © 2010 Elsevier Ltd. All rights reserved.

Corneal biomechanical properties in floppy eyelid syndrome.

PubMed

Muniesa, MaJesús; Muniesa Royo, MaJesús; March, Ana; March de Ribot, Ana; Sánchez-de-la-Torre, Manuel; Huerva, Valetín; Huerva Escanilla, Valetín; Jurjo, Carmen; Jurjo Campo, Carmen; Barbé, Ferran; Barbé Illa, Ferran

2015-05-01

To determine corneal biomechanical properties in patients with floppy eyelid syndrome (FES) and to compare them with eyes of controls. This case-control study included 208 eyes (72 eyes with FES and 136 without FES) of 107 patients (37 patients with FES and 70 without FES). Patients underwent a complete clinical eye examination that included corneal biomechanical evaluation carried out with the Reichert Ocular Response Analyzer. Corneal hysteresis (CH), corneal resistance factor (CRF), central corneal thickness (CCT), Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc) were evaluated. Mean CH was significantly lower in patients with FES than in those without FES (9.51 ± 1.56 vs. 11.66 ± 9.11; P < 0.001). These results remained statistically significant after adjusting for age and apnea-hypoapnea index (AHI) (P = 0.028). Mean CRF was 10.02 ± 2.08 in the group of patients with FES and 11.21 ± 5.36 in the group of patients without FES (P = 0.001). Mean IOPcc was 17.7 ± 4.8 in patients with FES and 16.3 ± 4.4 in those without FES (P = 0.036). After adjusting for age and AHI, these differences in CRF and IOPcc were not statistically significant (P = 0.26 and P = 0.87, respectively). No statistically significant difference was found between patients with and without FES for Goldmann-correlated intraocular pressure or CCT. Patients with FES had statistically lower CH values. Our findings suggest that corneal biomechanical properties could be changed in patients with FES, reflecting additional structural changes in FES.

The physiological and biomechanical effects of forwards and reverse sports wheelchair propulsion.

PubMed

Mason, Barry S; Lenton, John P; Goosey-Tolfrey, Victoria L

2015-07-01

To explore the physiological and biomechanical differences between forwards (FOR) and reverse (REV) sports wheelchair propulsion. Fourteen able-bodied males with previous wheelchair propulsion experience pushed a sports wheelchair on a single-roller ergometer in a FOR and REV direction at three sub-maximal speeds (4, 6, and 8 km/hour). Each trial lasted 3 minutes, and during the final minute physiological and biomechanical measures was collected. The physiological results revealed that oxygen uptake (1.51 ± 0.29 vs. 1.38 ± 0.26 L/minute, P = 0.005) and heart rate (121 ± 19 vs. 109 ± 14 beats/minute, P < 0.0005) were significantly greater during REV than FOR only during the 8 km/hour trials. From a biomechanical perspective, push frequencies were similar between FOR and REV across all speeds (P > 0.05). However, greater mean resultant forces were applied during FOR (P < 0.0005) at 4 km/hour (66.7 ± 19.5 vs. 49.2 ± 10.3 N), 6 km/hour (90.7 ± 21.9 vs. 65.3 ± 18.6 N), and 8 km/hour (102.5 ± 17.6 vs. 68.7 ± 13.5 N) compared to REV. Alternatively, push times and push angles were significantly lower (P ≤ 0.001) during FOR at each speed. The current study demonstrated that at higher speeds physiological demand becomes elevated during REV. This was likely to be associated with an inability to apply sufficient force to the wheels, thus requiring kinematic adaptations in order to maintain constant speeds in REV.

Influence of glucocorticosteroids on the biomechanical properties of in-vivo rabbit cornea.

PubMed

Yu, Ji-guo; Bao, Fang-jun; Joda, Akram; Fu, Xun-an; Zhou, Shi; Wang, Jing; Hu, Xiu-li; Wang, Qin-mei; Elsheikh, Ahmed

2014-01-01

Understanding corneal biomechanical responses during long-term glucocorticosteroids administration is important in clinical practice. The purpose of this study is to investigate the biomechanical influence of fluorometholone 0.1% eye drops on rabbit cornea. Thirty-eight Japanese white rabbits were randomly divided into three groups; a fluorometholone group, a supernatant group and a blank control group. For each rabbit in fluorometholone group, one cornea was treated with fluorometholone 0.1% eye drops four times a day for 8 weeks, while corneas of rabbits in supernatant group were treated in the same frequency with supernatant fraction centrifuged from fluorometholone 0.1% eye drops. The rabbits in the blank control group were not given any treatment. At the end of the 8 week observation period, the rabbits were euthanized and the eyes immediately enucleated and prepared for inflation testing. The experimental pressure-deformation data was used to derive the stress-strain behavior of each eye using an inverse modeling procedure. Comparisons of mechanical stiffness of corneas were conducted among the three groups to determine the influence of fluorometholone. The results showed that corneal stiffness decreased as the fluorometholone administration time prolonged. Comparisons of tangent modulus indicated average stiffness reductions of 34.2% and 33.5% in the fluorometholone group compared to the supernatant and control groups, respectively, at the end of the observation period. The stiffness-reduction effect of fluorometholone on the cornea should be considered in clinical management, especially when administrating it to biomechanically weakened corneas, such as after refractive surgeries and in cases of keratoconus. © 2013 Published by Elsevier Ltd.

Robot-aided therapy on the upper limb of subacute and chronic stroke patients: a biomechanical approach.

PubMed

Mazzoleni, S; Filippi, M; Carrozza, M C; Posteraro, F; Puzzolante, L; Falchi, E

2011-01-01

The goal of this study is to propose a methodology for evaluating recovery mechanisms in subacute and chronic post-stroke patients after a robot-aided upper-limb therapy, using a set of biomechanical parameters. Fifty-six post-stroke subjects, thirteen subacute and forty-three chronic patients participated in the study. A 2 dof robotic system, implementing an "assist-as-needed" control strategy, was used. Biomechanical parameters related (i) to the speed measured at the robot's end-effector and (ii) to the movement's smoothness were computed. Outcome clinical measures show a decrease in motor impairment after the treatment both in chronic and subacute patients. All the biomechanical parameters show an improvement between admission and discharge. Our results show that the robot-aided training can contribute to reduce the motor impairment in both subacute and chronic patients and identify neurophysiological mechanisms underlying the different stages of motor recovery. © 2011 IEEE

The intervals method: a new approach to analyse finite element outputs using multivariate statistics

PubMed Central

De Esteban-Trivigno, Soledad; Püschel, Thomas A.; Fortuny, Josep

2017-01-01

Background In this paper, we propose a new method, named the intervals’ method, to analyse data from finite element models in a comparative multivariate framework. As a case study, several armadillo mandibles are analysed, showing that the proposed method is useful to distinguish and characterise biomechanical differences related to diet/ecomorphology. Methods The intervals’ method consists of generating a set of variables, each one defined by an interval of stress values. Each variable is expressed as a percentage of the area of the mandible occupied by those stress values. Afterwards these newly generated variables can be analysed using multivariate methods. Results Applying this novel method to the biological case study of whether armadillo mandibles differ according to dietary groups, we show that the intervals’ method is a powerful tool to characterize biomechanical performance and how this relates to different diets. This allows us to positively discriminate between specialist and generalist species. Discussion We show that the proposed approach is a useful methodology not affected by the characteristics of the finite element mesh. Additionally, the positive discriminating results obtained when analysing a difficult case study suggest that the proposed method could be a very useful tool for comparative studies in finite element analysis using multivariate statistical approaches. PMID:29043107

The biomechanical effect of transverse connectors use in a pre- and postlaminectomy model of the posterior cervical spine: an in vitro cadaveric study.

PubMed

Majid, Kamran; Gudipally, Manasa; Hussain, Mir; Moldavsky, Mark; Khalil, Saif

2011-12-15

An in vitro biomechanical study investigating the effect of transverse connectors on posterior cervical stabilization system in a laminectomy model. To evaluate the optimal design, number, and location of the transverse connectors in stabilizing long segment posterior instrumentation in the cervical spine. In the cervical spine, lateral mass screw (LMS) fixation is used for providing stability after decompression. Transverse connectors have been used to augment segmental posterior instrumentation. However, in the cervical region the optimal design, number, and the location of transverse connectors is not known. Seven fresh human cervicothoracic cadaveric spines (C2-T1) were tested by applying ±1.5 Nm moments in flexion (F), extension (E), lateral bending (LB), and axial rotation (AR). After testing the intact condition, LMS/rods were placed and then were tested with two different transverse connectors (top-loading connector [TL] and the head-to-head [HH] connector) in multiple levels, pre- and postlaminectomy (PL). LMS significantly reduced segmental motion by 77.2% in F, 75.6% in E, 86.6% in LB, and 86.1% in AR prelaminectomy and by 75.4% in F, 76% in E, 80.6% in LB, and 76.4% in AR postlaminectomy compared to intact (P < 0.05). Only in AR, PL constructs with HH connectors at C3 & C7, TL connectors at C4-C5 & C5-C6, and at C3-C4 & C6-C7 significantly reduced the range of motion by 12.9%, 11.9%, and 11.9%, respectively, compared to PL LMS (P < 0.05). No statistical significance was observed between TL connector and HH connector in all loading directions. The biomechanical advantage of transverse connectors is significant in AR, when using two connectors at the proximal and distal ends, compared to one connector. In a clinical setting, this data may guide surgeons on transverse connector configurations to consider during posterior cervical instrumentation.

The relationships among spatiotemporal collagen gene expression, histology, and biomechanics following full-length injury in the murine patellar tendon.

PubMed

Dyment, Nathaniel A; Kazemi, Namdar; Aschbacher-Smith, Lindsey E; Barthelery, Nicolas J; Kenter, Keith; Gooch, Cynthia; Shearn, Jason T; Wylie, Christopher; Butler, David L

2012-01-01

Tendon injuries are major orthopedic problems that worsen as the population ages. Type-I (Col1) and type-II (Col2) collagens play important roles in tendon midsubstance and tendon-to-bone insertion healing, respectively. Using double transgenic mice, this study aims to spatiotemporally monitor Col1 and Col2 gene expression, histology, and biomechanics up to 8 weeks following a full-length patellar tendon injury. Gene expression and histology were analyzed weekly for up to 5 weeks while mechanical properties were measured at 1, 2, 5, and 8 weeks. At week 1, the healing region displayed loose granulation tissue with little Col1 expression. Col1 expression peaked at 2 weeks, but the ECM was highly disorganized and hypercellular. By 3 weeks, Col1 expression had reduced and by 5 weeks, the ECM was generally aligned along the tendon axis. Col2 expression was not seen in the healing midsubstance or insertion at any time point. The biomechanics of the healing tissue was inadequate at all time points, achieving ultimate loads and stiffnesses of 48% and 63% of normal values by 8 weeks. Future studies will further characterize the cells within the healing midsubstance and insertion using tenogenic markers and compare these results to those of tendon cells during normal development. Copyright © 2011 Orthopaedic Research Society.

Rotational biomechanics of the elite golf swing: benchmarks for amateurs.

PubMed

Meister, David W; Ladd, Amy L; Butler, Erin E; Zhao, Betty; Rogers, Andrew P; Ray, Conrad J; Rose, Jessica

2011-08-01

The purpose of this study was to determine biomechanical factors that may influence golf swing power generation. Three-dimensional kinematics and kinetics were examined in 10 professional and 5 amateur male golfers. Upper-torso rotation, pelvic rotation, X-factor (relative hip-shoulder rotation), O-factor (pelvic obliquity), S-factor (shoulder obliquity), and normalized free moment were assessed in relation to clubhead speed at impact (CSI). Among professional golfers, results revealed that peak free moment per kilogram, peak X-factor, and peak S-factor were highly consistent, with coefficients of variation of 6.8%, 7.4%, and 8.4%, respectively. Downswing was initiated by reversal of pelvic rotation, followed by reversal of upper-torso rotation. Peak X-factor preceded peak free moment in all swings for all golfers, and occurred during initial downswing. Peak free moment per kilogram, X-factor at impact, peak X-factor, and peak upper-torso rotation were highly correlated to CSI (median correlation coefficients of 0.943, 0.943, 0.900, and 0.900, respectively). Benchmark curves revealed kinematic and kinetic temporal and spatial differences of amateurs compared with professional golfers. For amateurs, the number of factors that fell outside 1-2 standard deviations of professional means increased with handicap. This study identified biomechanical factors highly correlated to golf swing power generation and may provide a basis for strategic training and injury prevention.

Atelocollagen Enhances the Healing of Rotator Cuff Tendon in Rabbit Model.

PubMed

Suh, Dong-Sam; Lee, Jun-Keun; Yoo, Ji-Chul; Woo, Sang-Hun; Kim, Ga-Ram; Kim, Ju-Won; Choi, Nam-Yong; Kim, Yongdeok; Song, Hyun-Seok

2017-07-01

Failure of rotator cuff healing is a common complication despite the rapid development of surgical repair techniques for the torn rotator cuff. To verify the effect of atelocollagen on tendon-to-bone healing in the rabbit supraspinatus tendon compared with conventional cuff repair. Controlled laboratory study. A tear of the supraspinatus tendon was created and repaired in 46 New Zealand White rabbits. They were then randomly allocated into 2 groups (23 rabbits per group; 15 for histological and 8 for biomechanical test). In the experimental group, patch-type atelocollagen was implanted between bone and tendon during repair; in the control group, the torn tendon was repaired without atelocollagen. Each opposite shoulder served as a sham (tendon was exposed only). Histological evaluation was performed at 4, 8, and 12 weeks. Biomechanical tensile strength was tested 12 weeks after surgery. Histological evaluation scores of the experimental group (4.0 ± 1.0) were significantly superior to those of the control group (7.7 ± 2.7) at 12 weeks ( P = .005). The load to failure was significantly higher in the experimental group (51.4 ± 3.9 N) than in the control group (36.4 ± 5.9 N) ( P = .001). Histological and biomechanical studies demonstrated better results in the experimental group using atelocollagen in a rabbit model of the supraspinatus tendon tear. Atelocollagen patch could be used in the cuff repair site to enhance healing.

Reconstruction of radial bone defect in rat by calcium silicate biomaterials.

PubMed

Oryan, Ahmad; Alidadi, Soodeh

2018-05-15

Despite many attempts, an appropriate therapeutic method has not yet been found to enhance bone formation, mechanical strength and structural and functional performances of large bone defects. In the present study, the bone regenerative potential of calcium silicate (CS) biomaterials combined with chitosan (CH) as calcium silicate/chitosan (CSC) scaffold was investigated in a critical radial bone defect in a rat model. The bioimplants were bilaterally implanted in the defects of 20 adult Sprague-Dawley rats. The rats were euthanized and the bone specimens were harvested at the 56th postoperative day. The healed radial bones were evaluated by three-dimensional CT, radiology, histomorphometric analysis, biomechanics, and scanning electron microscopy. The XRD analysis of the CS biomaterial showed its similarity to wollastonite (β-SiCO 3 ). The degradation rate of the CSC scaffold was much higher and it induced milder inflammatory reaction when compared to the CH alone. More bone formation and higher biomechanical performance were observed in the CSC treated group in comparison with the CH treated ones in histological, CT scan and biomechanical examinations. Scanning electron microscopic observation demonstrated the formation of more hydroxyapatite crystals in the defects treated with CSC. This study showed that the CSC biomaterials could be used as proper biodegradable materials in the field of bone reconstruction and tissue engineering. Copyright © 2018 Elsevier Inc. All rights reserved.

How effective are geometric morphometric techniques for assessing functional shape variation? An example from the great ape temporomandibular joint.

PubMed

Terhune, Claire E

2013-08-01

Functional shape analyses have long relied on the use of shape ratios to test biomechanical hypotheses. This method is powerful because of the ease with which results are interpreted, but these techniques fall short in quantifying complex morphologies that may not have a strong biomechanical foundation but may still be functionally informative. In contrast, geometric morphometric methods are continually being adopted for quantifying complex shapes, but they tend to prove inadequate in functional analyses because they have little foundation in an explicit biomechanical framework. The goal of this study was to evaluate the intersection of these two methods using the great ape temporomandibular joint as a case study. Three-dimensional coordinates of glenoid fossa and mandibular condyle shape were collected using a Microscribe digitizer. Linear distances extracted from these landmarks were analyzed using a series of one-way ANOVAs; further, the landmark configurations were analyzed using geometric morphometric techniques. Results suggest that the two methods are broadly similar, although the geometric morphometric data allow for the identification of shape differences among taxa that were not immediately apparent in the univariate analyses. Furthermore, this study suggests several new approaches for translating these shape data into a biomechanical context by adjusting the data using a biomechanically relevant variable. Copyright © 2013 Wiley Periodicals, Inc.

Reliability of 3-Dimensional Measures of Single-Leg Drop Landing Across 3 Institutions: Implications for Multicenter Research for Secondary ACL-Injury Prevention.

PubMed

Myer, Gregory D; Bates, Nathaniel A; DiCesare, Christopher A; Barber Foss, Kim D; Thomas, Staci M; Wordeman, Samuel C; Sugimoto, Dai; Roewer, Benjamin D; Medina McKeon, Jennifer M; Di Stasi, Stephanie L; Noehren, Brian W; McNally, Michael; Ford, Kevin R; Kiefer, Adam W; Hewett, Timothy E

2015-05-01

Due to the limitations of single-center studies in achieving appropriate sampling with relatively rare disorders, multicenter collaborations have been proposed to achieve desired sampling levels. However, documented reliability of biomechanical data is necessary for multicenter injury-prevention studies and is currently unavailable. To measure the reliability of 3-dimensional (3D) biomechanical waveforms from kinetic and kinematic variables during a single-leg landing (SLL) performed at 3 separate testing facilities. Multicenter reliability study. 3 laboratories. 25 female junior varsity and varsity high school volleyball players who visited each facility over a 1-mo period. Subjects were instrumented with 43 reflective markers to record 3D motion as they performed SLLs. During the SLL the athlete balanced on 1 leg, dropped down off of a 31-cm-high box, and landed on the same leg. Kinematic and kinetic data from both legs were processed from 2 trials across the 3 laboratories. Coefficients of multiple correlations (CMC) were used to statistically compare each joint angle and moment waveform for the first 500 ms of landing. Average CMC for lower-extremity sagittal-plane motion was excellent between laboratories (hip .98, knee .95, ankle .99). Average CMC for lower-extremity frontal-plane motion was also excellent between laboratories (hip .98, knee .80, ankle .93). Kinetic waveforms were repeatable in each plane of rotation (3-center mean CMC ≥.71), while knee sagittal-plane moments were the most consistent measure across sites (3-center mean CMC ≥.94). CMC waveform comparisons were similar relative to the joint measured to previously published reports of between-sessions reliability of sagittal- and frontal-plane biomechanics performed at a single institution. Continued research is needed to further standardize technology and methods to help ensure that highly reliable results can be achieved with multicenter biomechanical screening models.

Cross-sectional and longitudinal study of the impact of posterior meniscus horn lesions on adjacent cartilage composition, patient-reported outcomes and gait biomechanics in subjects without radiographic osteoarthritis.

PubMed

Russell, C; Pedoia, V; Souza, R B; Majumdar, S

2017-05-01

The aim of this study was to assess cross-sectional and longitudinal effects of meniscal lesions on adjacent cartilage T 1ρ and T 2 relaxation times, patient-reported outcomes and gait biomechanics. Thirty patients with no cartilage morphological defects reported by Whole Organ MRI Score (WORMS) magnetic resonance imaging (MRI) grading and no radiographic osteoarthritis (OA) (Kellgren--Lawrence (KL) ≤ 1) were selected, 15 with posterior meniscus horn lesions and 15 matched controls without meniscal lesions. All were imaged on a 3T MR scanner for three consecutive years, except those who dropped from the study. Sagittal and frontal plane kinematic gait data were acquired at baseline. The Knee Injury and Osteoarthritis Outcome Score (KOOS) survey was taken each time. All images were automatically segmented and registered to an atlas for voxel-by-voxel cross-sectional and longitudinal analyses. Relaxation time comparisons between groups showed elevated T 1ρ of the lateral tibia (LP) and elevated T 2 of the medial tibia (MT) and LT at 1 and 2 years in the lesion group. Longitudinal comparisons within each group revealed greater relaxation time elevations over one and 2 years in the group with lesions. KOOS Quality of Life (QOL) was significantly different between the groups at all time points (P < 0.05), as were other KOOS subcategories. No significant differences in the frontal or sagittal biomechanics were observed between the groups at baseline. Individuals with healthy cartilage and posterior meniscal horn lesions have increased relaxation times when compared to matched controls, increased relaxation time changes over 2 years, and consistently report a lower KOOS QOL, yet show no difference in gait biomechanics. Copyright © 2016 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Are Squats and Lunges Safe in the Rehabilitation of Patients with Patellofemoral Pain?

PubMed Central

Wood, David; Metcalfe, Andrew; Dodge, Jen; Templeton-Ward, Oliver

2016-01-01

Objectives: Patello-femoral pain is a common presenting complaint in orthopaedic clinics, and initial management often involves exercise and quadriceps strengthening regimes. Squats and lunges have become a common part of physiotherapy regimes as well as many exercise programs. It has been our observation that some patients experience a deterioration in pain after starting squats and lunges, and there is no agreement about the safe use of these exercises. The aim of this paper is to review the clinical and biomechanical literature to assess the safety of squats and lunges of patients with patella-femoral or anterior knee pain. Methods: Systematic Review. A literature review was performed of the Pubmed and PEDro databases using a pre-defined search strategy. Titles were screened by both an orthopaedic surgeon and a physiotherapist, abstracts were reviewed and the final papers were selected for inclusion. Randomised trials or comparative cohort studies of exercise regimes were included from the clinical literature as well as systematic reviews or meta-analyses published in the last 5 years. Patello-femoral forces calculated either from in-vivo data or cadaveric simulations were included from the biomechanical literature. Results: The searches revealed 3237 titles, which were reduced to 27 papers for the literature review. The biomechanical literature clearly demonstrated increasing patello-femoral forces during squats with increasing flexion, peaking at 90° of flexion and then falling in deep flexion. Less data was available on lunges but findings were comparable to studies of squats. Forces in the PFJ experienced during squats and lunges are significantly greater than with open-chain exercises beyond 60° of knee flexion. There were 13 clinical studies and 8 systematic reviews identified, which demonstrated that exercise is an effective treatment for PF pain with no significant difference between closed or open chain exercises (one study only). However only one study included squats beyond 60° or lunges in their protocols, with the majority excluding these exercises or limiting the degree of knee flexion, and no study has examined the use of squats and lunges specifically. Conclusion: Whilst squats and lunges are commonly prescribed, they have been used relatively little in clinical trials and have not been investigated independently. The biomechanical literature demonstrates that forces are relatively low when knee flexion is limited, but that flexion up to 90° places the PFJ under significant load. Given the vulnerable patient population in which they are used, the use of squats and lunges up to 90° should be discouraged in orthopaedic rehabilitation.

Research on the traditional Chinese medicine treating gastrointestinal motility in diabetic rats by improving biomechanical remodeling and neuroendocrine regulation

PubMed Central

Tian, Jiaxing; Li, Min; Zhao, Jingbo; Li, Junling; Liu, Guifang; Zhen, Zhong; Cao, Yang; Gregersen, Hans; Tong, Xiaolin

2017-01-01

Previous studies have demonstrated that TWA, a Chinese herbal medicine, could significantly improve the symptoms of patients with diabetic gastrointestinal dysfunction. However, the specific mechanism of regulating intestinal peristalsis has not been found. This study aimed to discover TWA’s therapeutic mechanism for regulating intestinal motility. The intestinal propulsion rate of diabetic rats was significantly increased after treatment with TWA for 8 weeks. Aiming at the mechanical structure, biomechanical testing indicated that TWA can significantly decrease the no-load intestinal wall thickness, cross-sectional area, and angular spread in a zero-stress state. Notably, intestinal stress-strain curve shifted to the right, which indicated TWA can inhibit intestinal hyperplasia and hardening and improve biomechanical remodeling. Further study of the mechanism revealed that TWA significantly inhibited the expression of AGE in the villi, crypt, and muscle and RAGE in crypt and upregulated the expression of nerve regulator (PSD95, C-kit and SCF). Radioimmunoassay showed TWA treatment decreased levels of serum somatostatin and vasoactive intestinal peptide. Moreover, associations were found between the intestinal propulsion rate with the morphologic and biomechanical remodeling parameters, changes of nerve factors, and endocrine hormones. Morphologic and biomechanical remodeling of the intestinal wall are the pathologic basis of gastrointestinal dysfunction. TWA can benefit intestinal motility by improving biomechanical and morphologic remodeling and by regulating expression of neuroendocrine factors. The results showed that the effect of TWA was dose-dependent, the higher the dose, the greater is the improvement. Thus, traditional Chinese medicine might be a valuable tool for treating diabetic gastrointestinal dysfunction. PMID:28559973

A selection of biomechanical research problems: From modeling to experimentation

NASA Astrophysics Data System (ADS)

Abbasi, Cyrus Omid

The research undertakings within this manuscript illustrate the importance of biomechanics in today's science. Without doubt, biomechanics can be utilized to obtain a better understanding of many unsolved mysteries involved in the field of medicine. Moreover, biomechanics can be used to develop better prosthetic or surgical devices as well. Chapter 2 represents a medical problem, which has not been solved for more than a century. With the use of fundamental principles of biomechanics', a better insight of this problem and its possible causes were obtained. Chapter 3 investigates the mechanical interaction between the human teeth and some processed food products during mastication, which is a routine but crucial daily activity of a human being. Chapter 4 looks at a problem within the field of surgery. In this chapter the stability and reliability of two different Suturing-Techniques are explored. Chapters 5 and 6 represent new patent designs as a result of the investigations made in Chapter 4. Chapter 7 studies the impact and load transfer patterns during the collision between a child's head and the ground. All of the above mentioned chapters show the significance of biomechanics in solving a range of different medical problems that involve physical and or mechanical characters.

Teaching practices of the undergraduate introductory biomechanics faculty: a North American survey.

PubMed

Garceau, Luke R; Ebben, William P; Knudson, Duane V

2012-11-01

Instruction and assessment strategies of undergraduate introductory biomechanics instructors have yet to be comprehensively examined. The purpose of this study was to identify the current instruction and assessment practices of North American undergraduate introductory biomechanics instructors and equipment needed for effective instruction in lecture and laboratory sessions. One hundred and sixty-five respondents (age: 42.5 +/- 10.3 years) who currently teach or have taught an introductory biomechanics course in North America were recruited by electronic mail. Subjects completed a web-based survey, consisting of 60 open- and closed-ended questions. Pearson's correlation coefficients were used to assess relationships between instructor's familiarity with either the Biomechanics Concept Inventory or the NASPE Guidelines for Undergraduate Biomechanics, and instructor and course characteristics (number of years teaching, age, faculty rank, number of quizzes given, etc.) A number of variables were significantly (p < 0.05) correlated. Answers to open-ended questions were processed using content analysis, with results categorized in content areas including: instructor and course characteristics; lecture instruction; assessment and equipment; laboratory instruction; assessment and equipment; and instructor's perspectives. Many active learning strategies for lecture and laboratory instruction were identified by faculty. Limited student preparation and limited resources were noted as the instructor's most common challenges.

Biomechanics of the ankle-foot system during stair ambulation: implications for design of advanced ankle-foot prostheses.

PubMed

Sinitski, Emily H; Hansen, Andrew H; Wilken, Jason M

2012-02-02

Unilateral lower limb prosthesis users display temporal, kinematic, and kinetic asymmetries between limbs while ascending and descending stairs. These asymmetries are due, in part, to the inability of current prosthetic devices to effectively mimic normal ankle function. The purpose of this study was to provide a comprehensive set of biomechanical data for able-bodied and unilateral transtibial amputee (TTA) ankle-foot systems for level-ground (LG), stair ascent (SA), and stair descent (SD), and to characterize deviations from normal performance associated with prosthesis use. Ankle joint kinematics, kinetics, torque-angle curves, and effective shapes were calculated for twelve able-bodied individuals and twelve individuals with TTA. The data from this study demonstrated the prosthetic limb can more effectively mimic the range of motion and power output of a normal ankle-foot during LG compared to SA and SD. There were larger differences between the prosthetic and able-bodied limbs during SA and SD, most evident in the torque-angle curves and effective shapes. These data can be used by persons designing ankle-foot prostheses and provide comparative data for assessment of future ankle-foot prosthesis designs. Published by Elsevier Ltd.

Biomechanics of Wheat/Barley Straw and Corn Stover

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

Christopher T. Wright; Peter A. Pryfogle; Nathan A. Stevens

2005-03-01

The lack of understanding of the mechanical characteristics of cellulosic feedstocks is a limiting factor in economically collecting and processing crop residues, primarily wheat and barley stems and corn stover. Several testing methods, including compression, tension, and bend have been investigated to increase our understanding of the biomechanical behavior of cellulosic feedstocks. Biomechanical data from these tests can provide required input to numerical models and help advance harvesting, handling, and processing techniques. In addition, integrating the models with the complete data set from this study can identify potential tools for manipulating the biomechanical properties of plant varieties in such amore » manner as to optimize their physical characteristics to produce higher value biomass and more energy efficient harvesting practices.« less