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Sample records for human tendon fascicles

  1. Passive mechanical properties of human gastrocnemius muscle tendon units, muscle fascicles and tendons in vivo.

    PubMed

    Hoang, P D; Herbert, R D; Todd, G; Gorman, R B; Gandevia, S C

    2007-12-01

    This study provides the first in vivo measures of the passive length-tension properties of relaxed human muscle fascicles and their tendons. A new method was used to derive passive length-tension properties of human gastrocnemius muscle-tendon units from measures of ankle stiffness obtained at a range of knee angles. Passive length-tension curves of the muscle-tendon unit were then combined with ultrasonographic measures of muscle fascicle length and pennation to determine passive length-tension curves of the muscle fascicles and tendons. Mean slack lengths of the fascicles, tendons and whole muscle-tendon units were 3.3+/-0.5 cm, 39.5+/-1.6 cm and 42.3+/-1.5 cm, respectively (means +/- s.d., N=6). On average, the muscle-tendon units were slack (i.e. their passive tension was zero) over the shortest 2.3+/-1.2 cm of their range. With combined changes of knee and ankle angles, the maximal increase in length of the gastrocnemius muscle-tendon unit above slack length was 6.7+/-1.9 cm, of which 52.4+/-11.7% was due to elongation of the tendon. Muscle fascicles and tendons underwent strains of 86.4+/-26.8% and 9.2+/-4.1%, respectively, across the physiological range of lengths. We conclude that the relaxed human gastrocnemius muscle-tendon unit falls slack over about one-quarter of its in vivo length and that muscle fascicle strains are much greater than tendon strains. Nonetheless, because the tendons are much longer than the muscle fascicles, tendons contribute more than half of the total compliance of the muscle-tendon unit.

  2. In vivo passive mechanical behaviour of muscle fascicles and tendons in human gastrocnemius muscle-tendon units.

    PubMed

    Herbert, Robert D; Clarke, Jillian; Kwah, Li Khim; Diong, Joanna; Martin, Josh; Clarke, Elizabeth C; Bilston, Lynne E; Gandevia, Simon C

    2011-11-01

    Ultrasound imaging was used to measure the length of muscle fascicles in human gastrocnemius muscles while the muscle was passively lengthened and shortened by moving the ankle. In some subjects the muscle belly 'buckled' at short lengths. When the gastrocnemius muscle-tendon unit was passively lengthened from its shortest in vivo length by dorsiflexing the ankle, increases in muscle-tendon length were not initially accompanied by increases in muscle fascicle lengths (fascicle length remained constant), indicating muscle fascicles were slack at short muscle-tendon lengths. The muscle-tendon length at which slack is taken up differs among fascicles: some fascicles begin to lengthen at very short muscle-tendon lengths whereas other fascicles remain slack over a large range of muscle-tendon lengths. This suggests muscle fascicles are progressively 'recruited' and contribute sequentially to muscle-tendon stiffness during passive lengthening of the muscle-tendon unit. Even above their slack lengths muscle fascicles contribute only a small part (<~30%) of the total change in muscle-tendon length. The contribution of muscle fascicles to muscle-tendon length increases with muscle length. The novelty of this work is that it reveals a previously unrecognised phenomenon (buckling at short lengths), posits a new mechanism of passive mechanical properties of muscle (recruitment of muscle fascicles), and confirms with high-resolution measurements that the passive compliance of human gastrocnemius muscle-tendon units is due largely to the tendon. It would be interesting to investigate if adaptations of passive properties of muscles are associated with changes in the distribution of muscle lengths at which fascicles fall slack.

  3. Functionally distinct tendon fascicles exhibit different creep and stress relaxation behaviour.

    PubMed

    Shepherd, Jennifer H; Legerlotz, Kirsten; Demirci, Taylan; Klemt, Christian; Riley, Graham P; Screen, Hazel R C

    2014-01-01

    Most overuse tendinopathies are thought to be associated with repeated microstrain below the failure threshold, analogous to the fatigue failure that affects materials placed under repetitive loading. Investigating the progression of fatigue damage within tendons is therefore of critical importance. There are obvious challenges associated with the sourcing of human tendon samples for in vitro analysis so animal models are regularly adopted. However, data indicates that fatigue life varies significantly between tendons of different species and with different stresses in life. Positional tendons such as rat tail tendon or the bovine digital extensor are commonly applied in in vitro studies of tendon overuse, but there is no evidence to suggest their behaviour is indicative of the types of human tendon particularly prone to overuse injuries. In this study, the fatigue response of the largely positional digital extensor and the more energy storing deep digital flexor tendon of the bovine hoof were compared to the semitendinosus tendon of the human hamstring. Fascicles from each tendon type were subjected to either stress or strain controlled fatigue loading (cyclic creep or cyclic stress relaxation respectively). Gross fascicle mechanics were monitored after cyclic stress relaxation and the mean number of cycles to failure investigated with creep loading. Bovine extensor fascicles demonstrated the poorest fatigue response, while the energy storing human semitendinosus was the most fatigue resistant. Despite the superior fatigue response of the energy storing tendons, confocal imaging suggested a similar degree of damage in all three tendon types; it appears the more energy storing tendons are better able to withstand damage without detriment to mechanics.

  4. Cyclic tensile strain upregulates collagen synthesis in isolated tendon fascicles

    SciTech Connect

    Screen, Hazel R.C. . E-mail: H.R.C.Screen@qmul.ac.uk; Shelton, Julia C.; Bader, Dan L.; Lee, David A.

    2005-10-21

    Mechanical stimulation has been implicated as an important regulatory factor in tendon homeostasis. In this study, a custom-designed tensile loading system was used to apply controlled mechanical stimulation to isolated tendon fascicles, in order to examine the effects of 5% cyclic tensile strain at 1 Hz on cell proliferation and matrix synthesis. Sample viability and gross structural composition were maintained over a 24 h loading period. Data demonstrated no statistically significant differences in cell proliferation or glycosaminoglycan production, however, collagen synthesis was upregulated with the application of cyclic tensile strain over the 24 h period. Moreover, a greater proportion of the newly synthesised matrix was retained within the sample after loading. These data provide evidence of altered anabolic activity within tendon in response to mechanical stimuli, and suggest the importance of cyclic tensile loading for the maintenance of the collagen hierarchy within tendon.

  5. Capacity for sliding between tendon fascicles decreases with ageing in injury prone equine tendons: a possible mechanism for age-related tendinopathy?

    PubMed

    Thorpe, C T; Udeze, C P; Birch, H L; Clegg, P D; Screen, H Rc

    2013-01-08

    Age-related tendinopathy is common in both humans and horses; the initiation and progression of which is similar between species. The majority of tendon injuries occur to high-strain energy storing tendons, such as the human Achilles tendon and equine superficial digital flexor (SDFT). By contrast, the low-strain positional human anterior tibialis tendon and equine common digital extensor (CDET) are rarely injured. It has previously been established that greater extension occurs at the fascicular interface in the SDFT than in the CDET; this may facilitate the large strains experienced during locomotion in the SDFT without damage occurring to the fascicles. This study investigated the alterations in whole tendon, fascicle and interfascicular mechanical properties in the SDFT and CDET with increasing age. It was hypothesised that the amount of sliding at the fascicular interface in the SDFT would decrease with increasing horse age, whereas the properties of the interface in the CDET would remain unchanged with ageing. Data support the hypothesis; there were no alterations in the mechanical properties of the whole SDFT or its constituent fascicles with increasing age. However, there was significantly less sliding at the fascicular interface at physiological loads in samples from aged tendons. There was no relationship between fascicle sliding and age in the CDET. The increase in stiffness of the interfascicular matrix in aged SDFT may result in the fascicles being loaded at an earlier point in the stress strain curve, increasing the risk of damage. This may predispose aged tendons to tendinopathy.

  6. Interaction between gastrocnemius medialis fascicle and Achilles tendon compliance: a new insight on the quick-release method.

    PubMed

    Farcy, Stevy; Nordez, Antoine; Dorel, Sylvain; Hauraix, Hugo; Portero, Pierre; Rabita, Giuseppe

    2014-02-01

    The insufficient temporal resolution of imaging devices has made the analysis of very fast movements, such as those required to measure active muscle-tendon unit stiffness, difficult. Thus the relative contributions of tendon, aponeurosis, and fascicle to muscle-tendon unit compliance remain to be determined. The present study analyzed the dynamic interactions of fascicle, tendon, and aponeurosis in human gastrocnemius medialis during the first milliseconds of an ankle quick-release movement, using high-frame-rate ultrasonography (2,000 frames/s). Nine subjects performed the tests in random order at six levels of maximal voluntary contraction (MVC) (30% to 80% of MVC). These tests were carried out with the ultrasound probe placed on the muscle belly and on the myotendinous junction. Tendon, muscle fascicle, and aponeurosis length changes were quantified in relation to shortening of the muscle-tendon unit during the first few milliseconds following the release. The tendon was the main contributor (around 72%) to the shortening of the muscle-tendon unit, whereas the muscle fascicle and aponeurosis contributions were 18% and 10%, respectively. Because these structures can be considered in series, the quantified contributions can be regarded as relative contributions to muscle-tendon compliance. These contributions were not modified with the level of MVC or the time range used for the analysis between 10 and 25 ms. The constant contribution of tendon, muscle fascicle, and aponeurosis to muscle-tendon unit compliance may help to simplify the mechanism of compliance regulation and to maintain the important role of tendons in enhancing work output and movement efficiency.

  7. A new strain energy function for modelling ligaments and tendons whose fascicles have a helical arrangement of fibrils.

    PubMed

    Shearer, Tom

    2015-09-18

    A new strain energy function for the hyperelastic modelling of ligaments and tendons whose fascicles have a helical arrangement of fibrils is derived. The stress-strain response of a single fascicle whose fibrils exhibit varying levels of crimp throughout its radius is calculated and used to determine the form of the strain energy function. The new constitutive law is used to model uniaxial extension test data for human patellar tendon and is shown to provide an excellent fit, with the average relative error being 9.8%. It is then used to model shear and predicts that the stresses required to shear a tendon are much smaller than those required to uniaxially stretch it to the same strain level. Finally, the strain energy function is used to model ligaments and tendons whose fascicles are helical, and the relative effects of the fibril helix angle, the fascicle helix angle and the fibril crimp variable are compared. It is shown that they all have a significant effect; the fibril crimp variable governs the non-linearity of the stress-strain curve, whereas the helix angles primarily affect its stiffness. Smaller values of the helix angles lead to stiffer tendons; therefore, the model predicts that one would expect to see fewer helical sub-structures in stiff positional tendons, and more in those that are required to be more flexible.

  8. Fascicles and the interfascicular matrix show decreased fatigue life with ageing in energy storing tendons.

    PubMed

    Thorpe, Chavaunne T; Riley, Graham P; Birch, Helen L; Clegg, Peter D; Screen, Hazel R C

    2017-03-16

    Tendon is composed of rope-like fascicles bound together by interfascicular matrix (IFM). The IFM is critical for the function of energy storing tendons, facilitating sliding between fascicles to allow these tendons to cyclically stretch and recoil. This capacity is required to a lesser degree in positional tendons. We have previously demonstrated that both fascicles and IFM in energy storing tendons have superior fatigue resistance compared with positional tendons, but the effect of ageing on the fatigue properties of these different tendon subunits has not been determined. Energy storing tendons become more injury-prone with ageing, indicating reduced fatigue resistance, hence we tested the hypothesis that the decline in fatigue life with ageing in energy storing tendons would be more pronounced in the IFM than in fascicles. We further hypothesised that tendon subunit fatigue resistance would not alter with ageing in positional tendons. Fascicles and IFM from young and old energy storing and positional tendons were subjected to cyclic fatigue testing until failure, and mechanical properties were calculated. The results show that both IFM and fascicles from the SDFT exhibit a similar magnitude of reduced fatigue life with ageing. By contrast, the fatigue life of positional tendon subunits was unaffected by ageing. The age-related decline in fatigue life of tendon subunits in energy storing tendons is likely to contribute to the increased risk of injury in aged tendons. Full understanding of the mechanisms resulting in this reduced fatigue life will aid in the development of treatments and interventions to prevent age-related tendinopathy.

  9. Concurrent deficits of soleus and gastrocnemius muscle fascicles and Achilles tendon post stroke.

    PubMed

    Zhao, Heng; Ren, Yupeng; Roth, Elliot J; Harvey, Richard L; Zhang, Li-Qun

    2015-04-01

    Calf muscles and Achilles tendon play important roles in functional activities. However, it is not clear how biomechanical properties of the uniarticular soleus (SOL) and biarticular gastrocnemius muscle and Achilles tendon, including the fascicle length, pennation angle, and stiffness, change concurrently post stroke. Biomechanical properties of the medial gastrocnemius (GM) and soleus muscles were evaluated bilaterally in 10 hemiparetic stroke survivors using combined ultrasonography-biomechanical measurements. Biomechanical properties of the Achilles tendon including the length, cross-sectional area (CSA), stiffness, and Young's modulus were evaluated, together with calf muscle biomechanical properties. Gastrocnemius and SOL contributions were separated using flexed and extended knee positions. The impaired side showed decreased fascicle length (GM: 6%, P = 0.002 and SOL: 9%, P = 0.03, at full knee extension and 0° ankle dorsiflexion) and increased fascicular stiffness (GM: 64%, P = 0.005 and SOL: 19%, P = 0.012, at a common 50 N force level). In contrast, Achilles tendon on the impaired side showed changes in the opposite direction as the muscle fascicles with increased tendon length (5%, P < 0.001), decreased tendon CSA (5%, P = 0.04), decreased tendon stiffness (42%, P < 0.001) and Young's modulus (30%, P < 0.001) compared with the unimpaired side. The fascicle and tendon stiffness changes were correlated negatively to the corresponding fascicle and tendon length changes, and decrease in Achilles tendon stiffness was correlated to the increases of SOL and GM fascicular stiffness (P < 0.05). Characterizations of calf muscle fascicles and Achilles tendon biomechanical properties help us better understand concurrent changes of fascicles and tendon as part of the calf muscle-tendon unit and facilitate development of more effective treatments.

  10. GAG depletion increases the stress-relaxation response of tendon fascicles, but does not influence recovery.

    PubMed

    Legerlotz, Kirsten; Riley, Graham P; Screen, Hazel R C

    2013-06-01

    Cyclic and static loading regimes are commonly used to study tenocyte metabolism in vitro and to improve our understanding of exercise-associated tendon pathologies. The aims of our study were to investigate if cyclic and static stress relaxation affected the mechanical properties of tendon fascicles differently, if this effect was reversible after a recovery period, and if the removal of glycosaminoglycans (GAGs) affected sample recovery. Tendon fascicles were dissected frombovine-foot extensors and subjected to 14% cyclic (1Hz) or static tensile strain for 30min. Additional fascicles were incubated overnight in buffer with 0.5U chondroitinase ABC or in buffer alone prior to the static stress-relaxation regime. To assess the effect of different stress-relaxation regimes, a quasi-static test to failure was carried out, either directly post loading or after a 2h recovery period, and compared with unloaded control fascicles. Both stress-relaxation regimes led to a significant reduction in fascicle failure stress and strain, but this was more pronounced in the cyclically loaded specimens. Removal of GAGs led to more stress relaxation and greater reductions in failure stress after static loading compared to controls. The reduction in mechanical properties was partially reversible in all samples, given a recovery period of 2h. This has implications for mechanical testing protocols, as a time delay between fatiguing specimens and characterization of mechanical properties will affect the results. GAGs appear to protect tendon fascicles from fatigue effects, possibly by enabling sample hydration.

  11. Muscle spindles in human tibialis anterior encode muscle fascicle length changes.

    PubMed

    Day, James; Bent, Leah R; Birznieks, Ingvars; Macefield, Vaughan G; Cresswell, Andrew G

    2017-04-01

    Muscle spindles provide exquisitely sensitive proprioceptive information regarding joint position and movement. Through passively driven length changes in the muscle-tendon unit (MTU), muscle spindles detect joint rotations because of their in-parallel mechanical linkage to muscle fascicles. In human microneurography studies, muscle fascicles are assumed to follow the MTU and, as such, fascicle length is not measured in such studies. However, under certain mechanical conditions, compliant structures can act to decouple the fascicles, and, therefore, the spindles, from the MTU. Such decoupling may reduce the fidelity by which muscle spindles encode joint position and movement. The aim of the present study was to measure, for the first time, both the changes in firing of single muscle spindle afferents and changes in muscle fascicle length in vivo from the tibialis anterior muscle (TA) during passive rotations about the ankle. Unitary recordings were made from 15 muscle spindle afferents supplying TA via a microelectrode inserted into the common peroneal nerve. Ultrasonography was used to measure the length of an individual fascicle of TA. We saw a strong correlation between fascicle length and firing rate during passive ankle rotations of varying rates (0.1-0.5 Hz) and amplitudes (1-9°). In particular, we saw responses observed at relatively small changes in muscle length that highlight the sensitivity of the TA muscle to small length changes. This study is the first to measure spindle firing and fascicle dynamics in vivo and provides an experimental basis for further understanding the link between fascicle length, MTU length, and spindle firing patterns.NEW & NOTEWORTHY Muscle spindles are exquisitely sensitive to changes in muscle length, but recordings from human muscle spindle afferents are usually correlated with joint angle rather than muscle fascicle length. In this study, we monitored both muscle fascicle length and spindle firing from the human tibialis

  12. The interfascicular matrix enables fascicle sliding and recovery in tendon, and behaves more elastically in energy storing tendons.

    PubMed

    Thorpe, Chavaunne T; Godinho, Marta S C; Riley, Graham P; Birch, Helen L; Clegg, Peter D; Screen, Hazel R C

    2015-12-01

    While the predominant function of all tendons is to transfer force from muscle to bone and position the limbs, some tendons additionally function as energy stores, reducing the cost of locomotion. Energy storing tendons experience extremely high strains and need to be able to recoil efficiently for maximum energy storage and return. In the equine forelimb, the energy storing superficial digital flexor tendon (SDFT) has much higher failure strains than the positional common digital extensor tendon (CDET). However, we have previously shown that this is not due to differences in the properties of the SDFT and CDET fascicles (the largest tendon subunits). Instead, there is a greater capacity for interfascicular sliding in the SDFT which facilitates the greater extensions in this particular tendon (Thorpe et al., 2012). In the current study, we exposed fascicles and interfascicular matrix (IFM) from the SDFT and CDET to cyclic loading followed by a test to failure. The results show that IFM mechanical behaviour is not a result of irreversible deformation, but the IFM is able to withstand cyclic loading, and is more elastic in the SDFT than in the CDET. We also assessed the effect of ageing on IFM properties, demonstrating that the IFM is less able to resist repetitive loading as it ages, becoming stiffer with increasing age in the SDFT. These results provide further indications that the IFM is important for efficient function in energy storing tendons, and age-related alterations to the IFM may compromise function and predispose older tendons to injury.

  13. The interfascicular matrix enables fascicle sliding and recovery in tendon, and behaves more elastically in energy storing tendons

    PubMed Central

    Thorpe, Chavaunne T.; Godinho, Marta S.C.; Riley, Graham P.; Birch, Helen L.; Clegg, Peter D.; Screen, Hazel R.C.

    2015-01-01

    While the predominant function of all tendons is to transfer force from muscle to bone and position the limbs, some tendons additionally function as energy stores, reducing the cost of locomotion. Energy storing tendons experience extremely high strains and need to be able to recoil efficiently for maximum energy storage and return. In the equine forelimb, the energy storing superficial digital flexor tendon (SDFT) has much higher failure strains than the positional common digital extensor tendon (CDET). However, we have previously shown that this is not due to differences in the properties of the SDFT and CDET fascicles (the largest tendon subunits). Instead, there is a greater capacity for interfascicular sliding in the SDFT which facilitates the greater extensions in this particular tendon (Thorpe et al., 2012). In the current study, we exposed fascicles and interfascicular matrix (IFM) from the SDFT and CDET to cyclic loading followed by a test to failure. The results show that IFM mechanical behaviour is not a result of irreversible deformation, but the IFM is able to withstand cyclic loading, and is more elastic in the SDFT than in the CDET. We also assessed the effect of ageing on IFM properties, demonstrating that the IFM is less able to resist repetitive loading as it ages, becoming stiffer with increasing age in the SDFT. These results provide further indications that the IFM is important for efficient function in energy storing tendons, and age-related alterations to the IFM may compromise function and predispose older tendons to injury. PMID:25958330

  14. Corticosteroid administration alters the mechanical properties of isolated collagen fascicles in rat-tail tendon.

    PubMed

    Haraldsson, B T; Aagaard, P; Crafoord-Larsen, D; Kjaer, M; Magnusson, S P

    2009-10-01

    Overload tendon injuries are frequent in recreational and elite sports. The optimal treatment strategy remains unknown, but local administration of corticosteroids is one common treatment option. The direct effects of the corticosteroid administration on the tissue are not fully understood. The present study examined the biomechanical effects of intratendinous corticosteroid injections on healthy rat-tail tendon collagen fascicles. A total of 24 Wistar male rats were divided into (A) a corticosteroid group where the animals were injected in the tail tendon with methylprednisolone acetate, 1.0 mL of 40 mg/mL mixed with 1.0 mL 9% saline (n=12), and (B) a control group that was injected with 9% saline (n=12). Three days after the injections, the animals were sacrificed and single individual collagen fascicles were collected and underwent displacement to failure. Corticosteroid administration significantly reduced tensile fascicle yield strength by 16% and Young's modulus by 14% compared with sham treatment (10.5+/-0.8 vs 12.4+/-0.5 MPa, P< or =0.05, and 537+/-27 vs 641+/-30 MPa, P<0.05, respectively), while the strain properties were unaffected. Peak stress was similar between the two groups. There was no difference in fascicle diameter between the two groups.

  15. Tendon fascicles exhibit a linear correlation between Poisson's ratio and force during uniaxial stress relaxation.

    PubMed

    Reese, Shawn P; Weiss, Jeffrey A

    2013-03-01

    The underlying mechanisms for the viscoelastic behavior of tendon and ligament tissue are poorly understood. It has been suggested that both a flow-dependent and flow-independent mechanism may contribute at different structural levels. We hypothesized that the stress relaxation response of a single tendon fascicle is consistent with the flow-dependent mechanism described by the biphasic theory (Armstrong et al., 1984, "An Analysis of the Unconfined Compression of Articular Cartilage," ASME J. Biomech. Eng., 106, pp. 165-173). To test this hypothesis, force, lateral strain, and Poisson's ratio were measured as a function of time during stress relaxation testing of six rat tail tendon fascicles from a Sprague Dawley rat. As predicted by biphasic theory, the lateral strain and Poisson's ratio were time dependent, a large estimated volume loss was seen at equilibrium and there was a linear correlation between the force and Poisson's ratio during stress relaxation. These results suggest that the fluid dependent mechanism described by biphasic theory may explain some or all of the apparent viscoelastic behavior of single tendon fascicles.

  16. Age-related greater Achilles tendon compliance is not associated with larger plantar flexor muscle fascicle strains in senior women

    PubMed Central

    Csapo, R.; Malis, V.; Hodgson, J.

    2014-01-01

    The aim of the present study was to test the hypothesis that the age-associated decrease of tendon stiffness would necessitate greater muscle fascicle strains to produce similar levels of force during isometric contraction. Greater fascicle strains could force sarcomeres to operate in less advantageous regions of their force-length and force-velocity relationships, thus impairing the capacity to generate strong and explosive contractions. To test this hypothesis, sagittal-plane dynamic velocity-encoded phase-contrast magnetic resonance images of the gastrocnemius medialis (GM) muscle and Achilles tendon (AT) were acquired in six young (YW; 26.1 ± 2.3 yr) and six senior (SW; 76.7 ± 8.3 yr) women during submaximal isometric contraction (35% maximum voluntary isometric contraction) of the plantar flexor muscles. Multiple GM fascicle lengths were continuously determined by automatically tracking regions of interest coinciding with the end points of muscle fascicles evenly distributed along the muscle's proximo-distal length. AT stiffness and Young's modulus were measured as the slopes of the tendon's force-elongation and stress-strain curves, respectively. Despite significantly lower AT stiffness at older age (YW: 120.2 ± 52.3 N/mm vs. SW: 53.9 ± 44.4 N/mm, P = 0.040), contraction-induced changes in GM fascicle lengths were similar in both age groups at equal levels of absolute muscular force (4–5% fascicle shortening in both groups), and even significantly larger in YW (YW: 11–12% vs. SW: 6–8% fascicle shortening) at equal percentage of maximum voluntary contraction. These results suggest that factors other than AT stiffness, such as age-associated changes in muscle composition or fascicle slack, might serve as compensatory adaptations, limiting the degree of fascicle strains upon contraction. PMID:24505104

  17. Incorporating Plasticity of the Interfibrillar Matrix in Shear Lag Models is Necessary to Replicate the Multiscale Mechanics of Tendon Fascicles

    PubMed Central

    Szczesny, Spencer E.; Elliott, Dawn M.

    2015-01-01

    Despite current knowledge of tendon structure, the fundamental deformation mechanisms underlying tendon mechanics and failure are unknown. We recently showed that a shear lag model, which explicitly assumed plastic interfibrillar load transfer between discontinuous fibrils, could explain the multiscale fascicle mechanics, suggesting that fascicle yielding is due to plastic deformation of the interfibrillar matrix. However, it is unclear whether alternative physical mechanisms, such as elastic interfibrillar deformation or fibril yielding, also contribute to fascicle mechanical behavior. The objective of the current work was to determine if plasticity of the interfibrillar matrix is uniquely capable of explaining the multiscale mechanics of tendon fascicles including the tissue post-yield behavior. This was examined by comparing the predictions of a continuous fibril model and three separate shear lag models incorporating an elastic, plastic, or elastoplastic interfibrillar matrix with multiscale experimental data. The predicted effects of fibril yielding on each of these models were also considered. The results demonstrated that neither the continuous fibril model nor the elastic shear lag model can successfully predict the experimental data, even if fibril yielding is included. Only the plastic or elastoplastic shear lag models were capable of reproducing the multiscale tendon fascicle mechanics. Differences between these two models were small, although the elastoplastic model did improve the fit of the experimental data at low applied tissue strains. These findings suggest that while interfibrillar elasticity contributes to the initial stress response, plastic deformation of the interfibrillar matrix is responsible for tendon fascicle post-yield behavior. This information sheds light on the physical processes underlying tendon failure, which is essential to improve our understanding of tissue pathology and guide the development of successful repair. PMID:25262202

  18. Lubricin in human achilles tendon: The evidence of intratendinous sliding motion and shear force in achilles tendon.

    PubMed

    Sun, Yu-Long; Wei, Zhuang; Zhao, Chunfeng; Jay, Gregory D; Schmid, Thomas M; Amadio, Peter C; An, Kai-Nan

    2015-06-01

    Achilles tendon is one of the most commonly injured tendons. Mechanical force is regarded as a major causative factor. However, the biomechanics of Achilles tendon and mechanical mechanism of the injuries are unclear. Lubricin expresses at regions exposed to sliding motion and shear force in a number of tissues. This study investigated the distribution and concentration of lubricin in human Achilles tendons for better understanding the biomechanics of Achilles tendon. Achilles tendons were harvested from nine cadavers. Lubricin was extracted from various locations proximal to the calcaneal insertion and quantified with ELISA. The distribution of lubricin was investigated with immunohistochemistry. Lubricin was mainly identified at the interfaces of tendon fascicles, especially in the mid-portion of the tendon. The concentration of lubricin in Achilles tendons varied by individual and the distance from its calcaneal insertion. The distal portion of the tendon had a higher concentration of lubricin than the proximal regions of the tendon. This study suggests the presence of intratendinous sliding motion of fascicles and shear force at interfaces of fascicles in human Achilles tendon. Shear force could be an important mechanical factor for the development of Achilles tendinopathy and rupture.

  19. In situ cell-matrix mechanics in tendon fascicles and seeded collagen gels: implications for the multiscale design of biomaterials.

    PubMed

    Duncan, Neil A; Bruehlmann, Sabina B; Hunter, Christopher J; Shao, Xinxin; Kelly, Elizabeth J

    2014-01-01

    Designing biomaterials to mimic and function within the complex mechanobiological conditions of connective tissues requires a detailed understanding of the micromechanical environment of the cell. The objective of our study was to measure the in situ cell-matrix strains from applied tension in both tendon fascicles and cell-seeded type I collagen scaffolds using laser scanning confocal microscopy techniques. Tendon fascicles and collagen gels were fluorescently labelled to simultaneously visualise the extracellular matrix and cell nuclei under applied tensile strains of 5%. There were significant differences observed in the micromechanics at the cell-matrix scale suggesting that the type I collagen scaffold did not replicate the pattern of native tendon strains. In particular, although the overall in situ tensile strains in the matrix were quite similar (∼2.5%) between the tendon fascicles and the collagen scaffolds, there were significant differences at the cell-matrix boundary with visible shear across cell nuclei of >1 μm measured in native tendon which was not observed at all in the collagen scaffolds. Similarly, there was significant non-uniformity of intercellular strains with relative sliding observed between cell rows in tendon which again was not observed in the collagen scaffolds where the strain environment was much more uniform. If the native micromechanical environment is not replicated in biomaterial scaffolds, then the cells may receive incorrect or mixed mechanical signals which could affect their biosynthetic response to mechanical load in tissue engineering applications. This study highlights the importance of considering the microscale mechanics in the design of biomaterial scaffolds and the need to incorporate such features in computational models of connective tissues.

  20. Afferent contribution to locomotor muscle activity during unconstrained overground human walking: an analysis of triceps surae muscle fascicles.

    PubMed

    af Klint, R; Cronin, N J; Ishikawa, M; Sinkjaer, T; Grey, M J

    2010-03-01

    Plantar flexor series elasticity can be used to dissociate muscle-fascicle and muscle-tendon behavior and thus afferent feedback during human walking. We used electromyography (EMG) and high-speed ultrasonography concomitantly to monitor muscle activity and muscle fascicle behavior in 19 healthy volunteers as they walked across a platform. On random trials, the platform was dropped (8 cm, 0.9 g acceleration) or held at a small inclination (up to +/-3 degrees in the parasagittal plane) with respect to level ground. Dropping the platform in the mid and late phases of stance produced a depression in the soleus muscle activity with an onset latency of about 50 ms. The reduction in ground reaction force also unloaded the plantar flexor muscles. The soleus muscle fascicles shortened with a minimum delay of 14 ms. Small variations in platform inclination produced significant changes in triceps surae muscle activity; EMG increased when stepping on an inclined surface and decreased when stepping on a declined surface. This sensory modulation of the locomotor output was concomitant with changes in triceps surae muscle fascicle and gastrocnemius tendon length. Assuming that afferent activity correlates to these mechanical changes, our results indicate that within-step sensory feedback from the plantar flexor muscles automatically adjusts muscle activity to compensate for small ground irregularities. The delayed onset of muscle fascicle movement after dropping the platform indicates that at least the initial part of the soleus depression is more likely mediated by a decrease in force feedback than length-sensitive feedback, indicating that force feedback contributes to the locomotor activity in human walking.

  1. Hypoxia inhibits primary cilia formation and reduces cell-mediated contraction in stress-deprived rat tail tendon fascicles

    PubMed Central

    Lavagnino, Michael; Oslapas, Anna N.; Gardner, Keri L.; Arnoczky, Steven P.

    2016-01-01

    Summary Background Hypoxia, which is associated with chronic tendinopathy, has recently been shown to decrease the mechanosensitivity of some cells. Therefore, the purpose of this study was to determine the effect of hypoxia on the formation of elongated primary cilia (a mechanosensing organelle of tendon cells) in vitro and to determine the effect of hypoxia on cell-mediated contraction of stress-deprived rat tail tendon fascicles (RTTfs). Methods Tendon cells isolated from RTTfs were cultured under normoxic (21% O2) or hypoxic (1% O2) conditions for 24 hours. The cells were then stained for tubulin and the number of cells with elongated cilia counted. RTTfs from 1-month-old male Sprague-Dawley rats were also cultured under hypoxic and normoxic conditions for three days and tendon length measured daily. Results A significant (p=0.002) decrease in the percent of elongated cilia was found in cells maintained in hypoxic conditions (54.1%±12.2) when compared in normoxic conditions (71.7%±6.32). RTTfs in hypoxia showed a significant decrease in the amount of contraction compared to RTTfs in normoxia after two (p=0.007) and three (p=0.001) days. Conclusion The decreased incidence of elongated primary cilia in a hypoxic environment, as well as the decreased mechanoresponsiveness of tendon cells under these conditions may relate to the inability of some cases of chronic tendinopathy to respond to strain-based rehabilitation modalities (i.e. eccentric loading). PMID:27900292

  2. Human middle longitudinal fascicle: variations in patterns of anatomical connections

    PubMed Central

    Makris, N.; Preti, M. G.; Asami, T.; Pelavin, P.; Campbell, B.; Papadimitriou, G. M.; Kaiser, J.; Baselli, G.; Westin, C. F.; Shenton, M. E.; Kubicki, M.

    2012-01-01

    Based on high-resolution diffusion tensor magnetic resonance imaging (DTI) tractographic analyses in thirty-nine healthy adult subjects we derived patterns of connections and measures of volume and biophysical parameters, such as fractional anisotropy (FA) for the human middle longitudinal fascicle (MdLF). Compared to previous studies, we found that the cortical connections of the MdLF in humans appear to go beyond the superior temporal (STG) and angular (AG) gyri, extending to the temporal pole (TP), superior parietal lobule (SPL), supramarginal gyrus, precuneus and the occipital lobe (including the cuneus and lateral occipital areas). Importantly, the MdLF showed a striking lateralized pattern with predominant connections between the TP, STG and AG on the left and TP, STG and SPL on the right hemisphere. In light of the results of the present study, and of the known functional role of the cortical areas interconnected by the MdLF, we suggested that this fiber pathway might be related to language, high order auditory association, visuospatial and attention functions. PMID:22782432

  3. Effects of contraction intensity on muscle fascicle and stretch reflex behavior in the human triceps surae.

    PubMed

    Cronin, Neil J; Peltonen, Jussi; Ishikawa, Masaki; Komi, Paavo V; Avela, Janne; Sinkjaer, Thomas; Voigt, Michael

    2008-07-01

    The aims of this study were to examine changes in the distribution of a stretch to the muscle fascicles with changes in contraction intensity in the human triceps surae and to relate fascicle stretch responses to short-latency stretch reflex behavior. Thirteen healthy subjects were seated in an ankle ergometer, and dorsiflexion stretches (8 degrees ; 250 degrees /s) were applied to the triceps surae at different moment levels (0-100% of maximal voluntary contraction). Surface EMG was recorded in the medial gastrocnemius, soleus, and tibialis anterior muscles, and ultrasound was used to measure medial gastrocnemius and soleus fascicle lengths. At low forces, reflex amplitudes increased despite a lack of change or even a decrease in fascicle stretch velocities. At high forces, lower fascicle stretch velocities coincided with smaller stretch reflexes. The results revealed a decline in fascicle stretch velocity of over 50% between passive conditions and maximal force levels in the major muscles of the triceps surae. This is likely to be an important factor related to the decline in stretch reflex amplitudes at high forces. Because short-latency stretch reflexes contribute to force production and stiffness regulation of human muscle fibers, a reduction in afferent feedback from muscle spindles could decrease the efficacy of human movements involving the triceps surae, particularly where high force production is required.

  4. Is the human left middle longitudinal fascicle essential for language? A brain electrostimulation study.

    PubMed

    De Witt Hamer, Philip C; Moritz-Gasser, Sylvie; Gatignol, Peggy; Duffau, Hugues

    2011-06-01

    Human brain pathways required for language processing are poorly known. A new white matter tract in humans, the middle longitudinal fascicle, has recently been anatomically determined by diffusion tensor imaging and suggested to be essential for language. Our aim is to determine the importance of the middle longitudinal fascicle for language processing. This study is based on 8 patients with glioma resection at least involving the superior temporal gyrus of the left dominant hemisphere. Language is systematically examined pre- and postoperatively at 3 months. Intraoperative electrostimulation is used to map cortical and subcortical structures as functional boundaries of the glioma resection, including those essential for language processing. The resections are extensive (on average 62 ml, ranging from 21 to 111 ml) and include a large part of the middle longitudinal fascicle in all patients. Intraoperatively, no interference with picture naming is observed by electrostimulation of the middle longitudinal fascicle, while in all patients the inferior fronto-occipital fascicle is identified by eliciting semantic paraphasia as functional boundary. Postoperatively, no new permanent language deficits are detected by systematic language examination. Therefore, we suggest that the middle longitudinal fascicle may participate but is not essential for language processing.

  5. Microneurography in relation to intraneural topography: somatotopic organisation of median nerve fascicles in humans.

    PubMed Central

    Hallin, R G

    1990-01-01

    Microneurography was performed in median nerve sensory fascicles with concentric needle electrodes and with conventional tungsten microneedles. The latter electrodes preferentially recorded activity from the myelinated fibres in the whole fascicle. By contrast, due to its special design, a concentric needle can record activity selectively from even a small part of a fascicle. High amplitude signals in C fibres can be discriminated close to Schwann cells that envelope unmyelinated axons. Apart from being biased for activity in thin fibres, the concentric needles can also record signals from nearby myelinated fibres. The palmar receptive fields of such fibre groups were not congruent with the areas traditionally attributed to multiunit skin afferents in humans, namely the innervation zone(s) of one or two adjacent digital nerve(s). Instead, the multiunit fields often comprised small parts of a digital nerve innervation area, frequently only the pulp of a finger. Single units were always localised within previously screened multiunit areas. Contrary to some previously accepted tenets it is probable that single unit activity in myelinated fibres in these studies is recorded extra-axonally near to a node of Ranvier. The findings also suggest the presence of a somatotopy in human limb nerve fascicles, comparable to that previously established in the spinal cord and the somatosensory cortex. Images PMID:2246655

  6. Asymmetry, connectivity, and segmentation of the arcuate fascicle in the human brain.

    PubMed

    Fernández-Miranda, Juan C; Wang, Yibao; Pathak, Sudhir; Stefaneau, Lucia; Verstynen, Timothy; Yeh, Fang-Cheng

    2015-01-01

    The structure and function of the arcuate fascicle is still controversial. The goal of this study was to investigate the asymmetry, connectivity, and segmentation patterns of the arcuate fascicle. We employed diffusion spectrum imaging reconstructed by generalized q-sampling and we applied both a subject-specific approach (10 subjects) and a template approach (q-space diffeomorphic reconstruction of 30 subjects). We complemented our imaging investigation with fiber microdissection of five post-mortem human brains. Our results confirmed the highly leftward asymmetry of the arcuate fascicle. In the template, the left arcuate had a volume twice as large as the right one, and the left superior temporal gyrus provided five times more volume of fibers than its counterpart. We identified four cortical frontal areas of termination: pars opercularis, pars triangularis, ventral precentral gyrus, and caudal middle frontal gyrus. We found clear asymmetry of the frontal terminations at pars opercularis and ventral precentral gyrus. The analysis of patterns of connectivity revealed the existence of a strong structural segmentation in the left arcuate, but not in the right one. The left arcuate fascicle is formed by an inner or ventral pathway, which interconnects pars opercularis with superior and rostral middle temporal gyri; and an outer or dorsal pathway, which interconnects ventral precentral and caudal middle frontal gyri with caudal middle and inferior temporal gyri. The fiber microdissection results provided further support to our tractography studies. We propose the existence of primary and supplementary language pathways within the dominant arcuate fascicle with potentially distinct functional and lesional features.

  7. The occipitofrontal fascicle in humans: A quantitative, in vivo, DT-MRI study

    PubMed Central

    Makris, Nikos; Papadimitriou, George M.; Sorg, Scott; Kennedy, David N.; Caviness, Verne S.; Pandya, Deepak N.

    2013-01-01

    Since the existence of the occipitofrontal fascicle (OFF) in humans has remained controversial, we utilized diffusion tensor imaging (DT-MRI)-based segmentation and tractography to investigate its trajectory in vivo in the human. We found that the OFF is distinct from the subcallosal fasciculus or Muratoff’s bundle (MB) and extends from the dorsal and medial parts of the occipital lobe as well as the dorsal, medial and inferior parietal lobules to the dorsal and medial part of the prefrontal and premotor regions. In most of its course, it remains parallel to the corpus callosum, the caudate nucleus and the lateral ventricle. In the coronal plane, the OFF is discerned in the core of the white matter medial to the corona radiata and the superior longitudinal fascicle II (SLF II) and lateral to MB and the corpus callosum. The volumetric measurements of the stem portion of the OFF indicate that the OFF is smaller than the SLF II and the cingulum bundle. Since DT-MRI allows the visualization of OFF fibers leading to the projection areas but not to the origin or termination of these fibers, this has been extrapolated from the experimental data in non-human primates. The OFF may have a role in visual spatial processing along with SLF II. PMID:17681797

  8. In vivo maximal fascicle-shortening velocity during plantar flexion in humans.

    PubMed

    Hauraix, Hugo; Nordez, Antoine; Guilhem, Gaël; Rabita, Giuseppe; Dorel, Sylvain

    2015-12-01

    Interindividual variability in performance of fast movements is commonly explained by a difference in maximal muscle-shortening velocity due to differences in the proportion of fast-twitch fibers. To provide a better understanding of the capacity to generate fast motion, this study aimed to 1) measure for the first time in vivo the maximal fascicle-shortening velocity of human muscle; 2) evaluate the relationship between angular velocity and fascicle-shortening velocity from low to maximal angular velocities; and 3) investigate the influence of musculo-articular features (moment arm, tendinous tissues stiffness, and muscle architecture) on maximal angular velocity. Ultrafast ultrasound images of the gastrocnemius medialis were obtained from 31 participants during maximal isokinetic and light-loaded plantar flexions. A strong linear relationship between fascicle-shortening velocity and angular velocity was reported for all subjects (mean R(2) = 0.97). The maximal shortening velocity (V(Fmax)) obtained during the no-load condition (NLc) ranged between 18.8 and 43.3 cm/s. V(Fmax) values were very close to those of the maximal shortening velocity (V(max)), which was extrapolated from the F-V curve (the Hill model). Angular velocity reached during the NLc was significantly correlated with this V(Fmax) (r = 0.57; P < 0.001). This finding was in agreement with assumptions about the role of muscle fiber type, whereas interindividual comparisons clearly support the fact that other parameters may also contribute to performance during fast movements. Nevertheless, none of the biomechanical features considered in the present study were found to be directly related to the highest angular velocity, highlighting the complexity of the upstream mechanics that lead to maximal-velocity muscle contraction.

  9. Human tendon behaviour and adaptation, in vivo

    PubMed Central

    Magnusson, S Peter; Narici, Marco V; Maganaris, Constantinos N; Kjaer, Michael

    2008-01-01

    Tendon properties contribute to the complex interaction of the central nervous system, muscle–tendon unit and bony structures to produce joint movement. Until recently limited information on human tendon behaviour in vivo was available; however, novel methodological advancements have enabled new insights to be gained in this area. The present review summarizes the progress made with respect to human tendon and aponeurosis function in vivo, and how tendons adapt to ageing, loading and unloading conditions. During low tensile loading or with passive lengthening not only the muscle is elongated, but also the tendon undergoes significant length changes, which may have implications for reflex responses. During active loading, the length change of the tendon far exceeds that of the aponeurosis, indicating that the aponeurosis may more effectively transfer force onto the tendon, which lengthens and stores elastic energy subsequently released during unloading, in a spring-like manner. In fact, data recently obtained in vivo confirm that, during walking, the human Achilles tendon provides elastic strain energy that can decrease the energy cost of locomotion. Also, new experimental evidence shows that, contrary to earlier beliefs, the metabolic activity in human tendon is remarkably high and this affords the tendon the ability to adapt to changing demands. With ageing and disuse there is a reduction in tendon stiffness, which can be mitigated with resistance exercises. Such adaptations seem advantageous for maintaining movement rapidity, reducing tendon stress and risk of injury, and possibly, for enabling muscles to operate closer to the optimum region of the length–tension relationship. PMID:17855761

  10. Treadmill versus overground and barefoot versus shod comparisons of triceps surae fascicle behaviour in human walking and running.

    PubMed

    Cronin, Neil J; Finni, Taija

    2013-07-01

    Studies of human locomotion are commonly performed on a treadmill or overground, as well as with or without footwear. These testing modalities have been suggested to influence kinematics, kinetics and/or spatio-temporal variables differently. However, it is unclear whether they influence contractile behaviour at the level of the muscle fascicles. This has major relevance because results from studies performed with different combinations of the testing modalities are often compared. The present study used ultrasound to examine fascicle behaviour of the medial gastrocnemius (MG) and soleus muscles of ten young, healthy males during walking and running on a treadmill and overground, as well as barefoot and shod. Barefoot conditions resulted in modestly shorter step durations than corresponding shod conditions, whereas no consistent temporal differences were observed between overground and treadmill locomotion. For both comparisons, no differences were observed in soleus or MG fascicle behaviour between corresponding conditions in walking or running, although soleus consistently exhibited smaller, lower velocity length changes than MG. It is concluded that the examined testing modalities are equally valid for studying muscle fascicle behaviour during locomotion. This conclusion is supported by a comparison of our data to the results of 16 previous studies that used various combinations of testing modalities; muscle fascicle behaviour is qualitatively similar between studies for a given muscle and gait.

  11. Effect of Transducer Orientation on Errors in Ultrasound Image-Based Measurements of Human Medial Gastrocnemius Muscle Fascicle Length and Pennation

    PubMed Central

    Gandevia, Simon C.; Herbert, Robert D.

    2016-01-01

    Ultrasound imaging is often used to measure muscle fascicle lengths and pennation angles in human muscles in vivo. Theoretically the most accurate measurements are made when the transducer is oriented so that the image plane aligns with muscle fascicles and, for measurements of pennation, when the image plane also intersects the aponeuroses perpendicularly. However this orientation is difficult to achieve and usually there is some degree of misalignment. Here, we used simulated ultrasound images based on three-dimensional models of the human medial gastrocnemius, derived from magnetic resonance and diffusion tensor images, to describe the relationship between transducer orientation and measurement errors. With the transducer oriented perpendicular to the surface of the leg, the error in measurement of fascicle lengths was about 0.4 mm per degree of misalignment of the ultrasound image with the muscle fascicles. If the transducer is then tipped by 20°, the error increases to 1.1 mm per degree of misalignment. For a given degree of misalignment of muscle fascicles with the image plane, the smallest absolute error in fascicle length measurements occurs when the transducer is held perpendicular to the surface of the leg. Misalignment of the transducer with the fascicles may cause fascicle length measurements to be underestimated or overestimated. Contrary to widely held beliefs, it is shown that pennation angles are always overestimated if the image is not perpendicular to the aponeurosis, even when the image is perfectly aligned with the fascicles. An analytical explanation is provided for this finding. PMID:27294280

  12. Mechanical properties of human patellar tendon at the hierarchical levels of tendon and fibril.

    PubMed

    Svensson, René B; Hansen, Philip; Hassenkam, Tue; Haraldsson, Bjarki T; Aagaard, Per; Kovanen, Vuokko; Krogsgaard, Michael; Kjaer, Michael; Magnusson, S Peter

    2012-02-01

    Tendons are strong hierarchical structures, but how tensile forces are transmitted between different levels remains incompletely understood. Collagen fibrils are thought to be primary determinants of whole tendon properties, and therefore we hypothesized that the whole human patellar tendon and its distinct collagen fibrils would display similar mechanical properties. Human patellar tendons (n = 5) were mechanically tested in vivo by ultrasonography. Biopsies were obtained from each tendon, and individual collagen fibrils were dissected and tested mechanically by atomic force microscopy. The Young's modulus was 2.0 ± 0.5 GPa, and the toe region reached 3.3 ± 1.9% strain in whole patellar tendons. Based on dry cross-sectional area, the Young's modulus of isolated collagen fibrils was 2.8 ± 0.3 GPa, and the toe region reached 0.86 ± 0.08% strain. The measured fibril modulus was insufficient to account for the modulus of the tendon in vivo when fibril content in the tendon was accounted for. Thus, our original hypothesis was not supported, although the in vitro fibril modulus corresponded well with reported in vitro tendon values. This correspondence together with the fibril modulus not being greater than that of tendon supports that fibrillar rather than interfibrillar properties govern the subfailure tendon response, making the fibrillar level a meaningful target of intervention. The lower modulus found in vitro suggests a possible adverse effect of removing the tissue from its natural environment. In addition to the primary work comparing the two hierarchical levels, we also verified the existence of viscoelastic behavior in isolated human collagen fibrils.

  13. Superficial aponeurosis of human gastrocnemius is elongated during contraction: implications for modeling muscle-tendon unit.

    PubMed

    Muramatsu, Tadashi; Muraoka, Tetsuro; Kawakami, Yasuo; Fukunaga, Tetsuo

    2002-02-01

    Two questions were addressed in this study: (1) how much strain of the superficial aponeurosis of the human medial gastrocnemius muscle (MG) was obtained during voluntary isometric contractions in vivo, (2) whether there existed inhomogeneity of the strain along the superficial aponeurosis. Seven male subjects, whose knees were extended and ankles were flexed at right angle, performed isometric plantar flexion while elongation of superficial aponeurosis of MG was determined from the movements of the intersections made by the superficial aponeurosis and fascicles using ultrasonography. The strain of the superficial aponeurosis at the maximum voluntary contraction, estimated from the elongation and length data, was 5.6+/-1.2%. There was no significant difference in strain between the proximal and distal parts of the superficial aponeurosis. Based on the present result and that of our previous study for the same subjects (J. Appl. Physiol 90 (2001) 1671), a model was formulated for a contracting uni-pennate muscle-tendon unit. This model, which could be applied to isometric contractions at other angles and therefore of wide use, showed that similar strain between superficial and deep aponeuroses of MG contributed to homogeneous fascicle length change within MG during contractions. These findings would contribute to clarifying the functions of the superficial aponeurosis and the effects of the superficial aponeurosis elongation on the whole muscle behavior.

  14. Specialization of tendon mechanical properties results from interfascicular differences

    PubMed Central

    Thorpe, Chavaunne T.; Udeze, Chineye P.; Birch, Helen L.; Clegg, Peter D.; Screen, Hazel R. C.

    2012-01-01

    Tendons transfer force from muscle to bone. Specific tendons, including the equine superficial digital flexor tendon (SDFT), also store and return energy. For efficient function, energy-storing tendons need to be more extensible than positional tendons such as the common digital extensor tendon (CDET), and when tested in vitro have a lower modulus and failure stress, but a higher failure strain. It is not known how differences in matrix organization contribute to distinct mechanical properties in functionally different tendons. We investigated the properties of whole tendons, tendon fascicles and the fascicular interface in the high-strain energy-storing SDFT and low-strain positional CDET. Fascicles failed at lower stresses and strains than tendons. The SDFT was more extensible than the CDET, but SDFT fascicles failed at lower strains than CDET fascicles, resulting in large differences between tendon and fascicle failure strain in the SDFT. At physiological loads, the stiffness at the fascicular interface was lower in the SDFT samples, enabling a greater fascicle sliding that could account for differences in tendon and fascicle failure strain. Sliding between fascicles prior to fascicle extension in the SDFT may allow the large extensions required in energy-storing tendons while protecting fascicles from damage. PMID:22764132

  15. 3-D ultrastructure and collagen composition of healthy and overloaded human tendon: evidence of tenocyte and matrix buckling

    PubMed Central

    Pingel, Jessica; Lu, Yinhui; Starborg, Tobias; Fredberg, Ulrich; Langberg, Henning; Nedergaard, Anders; Weis, MaryAnn; Eyre, David; Kjaer, Michael; Kadler, Karl E

    2014-01-01

    Achilles tendinopathies display focal tissue thickening with pain and ultrasonography changes. Whilst complete rupture might be expected to induce changes in tissue organization and protein composition, little is known about the consequences of non-rupture-associated tendinopathies, especially with regards to changes in the content of collagen type I and III (the major collagens in tendon), and changes in tendon fibroblast (tenocyte) shape and organization of the extracellular matrix (ECM). To gain new insights, we took biopsies from the tendinopathic region and flanking healthy region of Achilles tendons of six individuals with clinically diagnosed tendinopathy who had no evidence of cholesterol, uric acid and amyloid accumulation. Biochemical analyses of collagen III/I ratio were performed on all six individuals, and electron microscope analysis using transmission electron microscopy and serial block face-scanning electron microscopy were made on two individuals. In the tendinopathic regions, compared with the flanking healthy tissue, we observed: (i) an increase in the ratio of collagen III : I proteins; (ii) buckling of the collagen fascicles in the ECM; (iii) buckling of tenocytes and their nuclei; and (iv) an increase in the ratio of small-diameter : large-diameter collagen fibrils. In summary, load-induced non-rupture tendinopathy in humans is associated with localized biochemical changes, a shift from large-to small-diameter fibrils, buckling of the tendon ECM, and buckling of the cells and their nuclei. PMID:24571576

  16. Tendon biomechanical properties enhance human wrist muscle specialization.

    PubMed

    Loren, G J; Lieber, R L

    1995-07-01

    Biomechanical properties of human wrist tendons were measured under loads predicted to be experienced by those tendons under physiological conditions. This was accomplished by measuring the architectural properties of the five prime wrist movers--extensors carpi radialis brevis (ECRB), extensor carpi radialis longus (ECRL), extensor carpi ulnaris (ECU), flexor carpi radials (FCR), flexor carpi ulnaris (FCU)--and predicting their maximum tension (P0) using a specific tension value (22.5 N cm-2. Loading the corresponding tendons to P0 resulted in significantly different strain among tendons (p < 0.01) with the largest strain observed in the FCU (3.68 +/- 0.31%) and the smallest strain observed in the ECRL (1.78 +/- 0.14%). Further, strain magnitude was significantly positively correlated with the tendon length-to-fiber length ratio of the muscle-tendon unit, a measure of the intrinsic compliance of the muscle-tendon unit. Theoretical modeling of the magnitude of muscle sarcomere shortening expected based on the measured biomechanical properties revealed a maximum sarcomere length decrease of about 0.6 micron for the FCU to a minimum of about 0.2 micron for the ECRB at P0. Thus, tendon compliance may, but does not necessarily, result in significant modification of muscle force generation. The significant variation in tendon biomechanical properties was not observed using traditional elongation-to-failure methods on the same specimens. Thus, the use of elongation-to-failure experiments for determination of tendon properties may not be reasonable when the purpose of such studies is to infer physiological function. These data indicate that muscle-tendon units show remarkable specialization and that tendon intrinsic properties accentuate the muscle architectural specialization already present.

  17. Temporal features of human tendon vibration illusions.

    PubMed

    Fuentes, Christina T; Gomi, Hiroaki; Haggard, Patrick

    2012-12-01

    Muscle spindles provide information about the position and movement of our bodies. One method for investigating spindle signals is tendon vibration. Vibration of flexor tendons can produce illusions of extension, and vibration of extensor tendons can produce illusions of flexion. Here we estimate the temporal resolution and persistence of these illusions. In Experiments 1 and 2, sequences of alternating vibration of wrist flexor and extensor tendons produced position illusions that varied with alternation period. When vibrations alternated at 1 Hz or slower, perceived position at the end of the sequence depended on the last vibration. When vibrations alternated every 0.3 s, perceived position was independent of the last vibration. Experiment 2 verified and extended these results using more trials and concurrent electromyographic recording. Although tendon vibrations sometimes induce reflexive muscle activity, we found no evidence that such activity contributed to these effects. Experiment 3 investigated how long position sense is retained when not updated by current information from spindles. Our first experiments suggested that vibrating antagonistic tendons simultaneously could produce conflicting inputs, leaving position sense reliant on memory of position prior to vibration onset. We compared variability in position sense after different durations of such double vibration. After 12 s of double vibration, variability across trials exceeded levels predicted from vibrations of flexor or extensor tendons alone. This suggests that position sense memory had decayed too much to substitute for the current conflicting sensory information. Together, our results provide novel, quantitative insight into the temporal properties of tendon vibration illusions.

  18. 3D curvature of muscle fascicles in triceps surae.

    PubMed

    Rana, Manku; Hamarneh, Ghassan; Wakeling, James M

    2014-12-01

    Muscle fascicles curve along their length, with the curvatures occurring around regions of high intramuscular pressure, and are necessary for mechanical stability. Fascicles are typically considered to lie in fascicle planes that are the planes visualized during dissection or two-dimensional (2D) ultrasound scans. However, it has previously been predicted that fascicles must curve in three-dimensional (3D) and thus the fascicle planes may actually exist as 3D sheets. 3D fascicle curvatures have not been explored in human musculature. Furthermore, if the fascicles do not lie in 2D planes, then this has implications for architectural measures that are derived from 2D ultrasound scans. The purpose of this study was to quantify the 3D curvatures of the muscle fascicles and fascicle sheets within the triceps surae muscles and to test whether these curvatures varied among different contraction levels, muscle length, and regions within the muscle. Six male subjects were tested for three torque levels (0, 30, and 60% maximal voluntary contraction) and four ankle angles (-15, 0, 15, and 30° plantar flexion), and fascicles were imaged using 3D ultrasound techniques. The fascicle curvatures significantly increased at higher ankle torques and shorter muscle lengths. The fascicle sheet curvatures were of similar magnitude to the fascicle curvatures but did not vary between contractions. Fascicle curvatures were regionalized within each muscle with the curvature facing the deeper aponeuroses, and this indicates a greater intramuscular pressure in the deeper layers of muscles. Muscle architectural measures may be in error when using 2D images for complex geometries such as the soleus.

  19. Substantial creep in healing human Achilles tendons. A pilot study

    PubMed Central

    Aspenberg, Per; Schepull, Thorsten

    2015-01-01

    Summary Background healing after rupture of the Achilles tendon can be described in terms of mechanical properties of the new-formed tissue, constituting the tendon callus. In previous human studies, the elastic modulus and the density remained almost constant during 3 months after mobilization started, and then improved up to one year. So far, time-dependent deformation of the healing human tendon has not been reported. Methods in a series of 16 patients, operated with Achilles tendon suture, we implanted tantalum beads into the tendon and measured the distance between them repeatedly during 3 min of constant loading, using an ordinary image intensifier. The patients unloaded their leg for 30 min before the test. To avoid bias, all images were investigated in a randomized and blinded order. Results total strain during 3 min of constant loading at 7 weeks post injury amounted to 5%, and at 19 weeks to 3%. About half of the strain, after the loading was applied, occurred during the second and third min. Considerable strain also occurred just before loading, when the patient was told that a load would be applied, but before this was actually done. Conclusion the measurements were crude, and this study should be seen as a pilot. Still, visco-elastic properties seem to dominate the mechanical behavior the healing Achilles tendon from start of mobilization to 19 weeks, at least when tested after 30 min rest. This deserves further studies with more precise methods. PMID:26605187

  20. In vivo measurement of fascicle length and pennation of the human anconeus muscle at several elbow joint angles.

    PubMed

    Stevens, Daniel E; Smith, Cameron B; Harwood, Brad; Rice, Charles L

    2014-11-01

    Ultrasound imaging has facilitated the reliable measure of the architectural variables fascicle length (LF ) and pennation angle (PA), at rest and during static and dynamic contractions in many human skeletal muscles in vivo. Despite its small size and very modest contribution to elbow extension torque, the anconeus muscle has proven a useful model for the study of neuromuscular function in health and disease. Recent single motor unit (MU) studies in the anconeus have reported discrete and identifiable individual trains of MU potentials from intramuscular electromyography (EMG) recordings during dynamic elbow extensions. It is unknown whether the anconeus has unique architectural features related to alterations in LF and PA throughout the elbow joint range of motion that may help explain these high-quality recordings. Previous anatomical studies have investigated this muscle in cadavers and at mainly one elbow joint angle. The purpose of this study was to measure in vivo PA and LF of the anconeus muscle in a relaxed state at different degrees of elbow flexion using ultrasonography. Ultrasound images were collected from 10 healthy males (25 ± 3 years) at 135°, 120°, 90°, 45°, and 0° of elbow flexion. Average values of LF decreased by 6 mm (10%), 6 mm (12%), and 4 mm (9%) from 135-120°, 120-90°, and 90-45° of elbow flexion, respectively, whereas average PA values increased by 1° (9%), 1° (8%), and 2° (14%) from 135-120°, 120-90°, and 45-0°, respectively. The results indicate that anconeus muscle architecture is dynamic, undergoing moderate changes with elbow joint excursion that are similar to other limb muscles reported elsewhere. The data obtained here are more comprehensive and representative of architectural changes at various elbow joint positions than those data reported in cadaveric studies. Furthermore, the results of this study indicate that despite experiencing similar relative changes in muscle architecture to other skeletal muscles

  1. Human hamstring tenocytes survive when seeded into a decellularized porcine Achilles tendon extracellular matrix.

    PubMed

    Lohan, Anke; Stoll, Christiane; Albrecht, Marit; Denner, Andreas; John, Thilo; Krüger, Kay; Ertel, Wolfgang; Schulze-Tanzil, Gundula

    2013-01-01

    Tendon ruptures and defects remain major orthopaedic challenges. Tendon healing is a time-consuming process, which results in scar tissue with an altered biomechanical competence. Using a xenogeneic tendon extracellular matrix (ECM) as a natural scaffold, which can be reseeded with autologous human tenocytes, might be a promising approach to reconstruct damaged tendons. For this purpose, the porcine Achilles (AS) tendons serving as a scaffold were histologically characterized in comparison to human cell donor tendons. AS tendons were decellularized and then reseeded with primary human hamstring tenocytes using cell centrifuging, rotating culture and cell injection techniques. Vitality testing, histology and glycosaminoglycan/DNA quantifications were performed to document the success of tendon reseeding. Porcine AS tendons were characterized by a higher cell and sulfated glycosaminoglycan content than human cell donor tendons. Complete decellularization could be achieved, but led to a wash out of sulfated glycosaminoglycans. Nevertheless, porcine tendon could be recellularized with vital human tenocytes. The recellularization led to a slight increase in cell number compared to the native tendon and some glycosaminoglycan recovery. This study indicates that porcine tendon can be de- and recellularized using adult human tenocytes. Future work should optimize cell distribution within the recellularized tendon ECM and consider tendon- and donor species-dependent differences.

  2. Ultrasound elasticity imaging of human posterior tibial tendon

    NASA Astrophysics Data System (ADS)

    Gao, Liang

    Posterior tibial tendon dysfunction (PTTD) is a common degenerative condition leading to a severe impairment of gait. There is currently no effective method to determine whether a patient with advanced PTTD would benefit from several months of bracing and physical therapy or ultimately require surgery. Tendon degeneration is closely associated with irreversible degradation of its collagen structure, leading to changes to its mechanical properties. If these properties could be monitored in vivo, it could be used to quantify the severity of tendonosis and help determine the appropriate treatment. Ultrasound elasticity imaging (UEI) is a real-time, noninvasive technique to objectively measure mechanical properties in soft tissue. It consists of acquiring a sequence of ultrasound frames and applying speckle tracking to estimate displacement and strain at each pixel. The goals of my dissertation were to 1) use acoustic simulations to investigate the performance of UEI during tendon deformation with different geometries; 2) develop and validate UEI as a potentially noninvasive technique for quantifying tendon mechanical properties in human cadaver experiments; 3) design a platform for UEI to measure mechanical properties of the PTT in vivo and determine whether there are detectable and quantifiable differences between healthy and diseased tendons. First, ultrasound simulations of tendon deformation were performed using an acoustic modeling program. The effects of different tendon geometries (cylinder and curved cylinder) on the performance of UEI were investigated. Modeling results indicated that UEI accurately estimated the strain in the cylinder geometry, but underestimated in the curved cylinder. The simulation also predicted that the out-of-the-plane motion of the PTT would cause a non-uniform strain pattern within incompressible homogeneous isotropic material. However, to average within a small region of interest determined by principal component analysis (PCA

  3. Methods of Assessing Human Tendon Metabolism and Tissue Properties in Response to Changes in Mechanical Loading.

    PubMed

    Heinemeier, Katja M; Kjaer, Michael; Magnusson, S Peter

    2016-01-01

    In recent years a number of methodological developments have improved the opportunities to study human tendon. Microdialysis enables sampling of interstitial fluid in the peritendon tissue, while sampling of human tendon biopsies allows direct analysis of tendon tissue for gene- and protein expression as well as protein synthesis rate. Further the (14)C bomb-pulse method has provided data on long-term tissue turnover in human tendon. Non-invasive techniques allow measurement of tendon metabolism (positron emission tomography (PET)), tendon morphology (magnetic resonance imaging (MRI)), and tendon mechanical properties (ultrasonography combined with force measurement during movement). Finally, 3D cell cultures of human tendon cells provide the opportunity to investigate cell-matrix interactions in response to various interventions.

  4. Biaxial tensile testing and constitutive modeling of human supraspinatus tendon.

    PubMed

    Szczesny, Spencer E; Peloquin, John M; Cortes, Daniel H; Kadlowec, Jennifer A; Soslowsky, Louis J; Elliott, Dawn M

    2012-02-01

    The heterogeneous composition and mechanical properties of the supraspinatus tendon offer an opportunity for studying the structure-function relationships of fibrous musculoskeletal connective tissues. Previous uniaxial testing has demonstrated a correlation between the collagen fiber angle distribution and tendon mechanics in response to tensile loading both parallel and transverse to the tendon longitudinal axis. However, the planar mechanics of the supraspinatus tendon may be more appropriately characterized through biaxial tensile testing, which avoids the limitation of nonphysiologic traction-free boundary conditions present during uniaxial testing. Combined with a structural constitutive model, biaxial testing can help identify the specific structural mechanisms underlying the tendon's two-dimensional mechanical behavior. Therefore, the objective of this study was to evaluate the contribution of collagen fiber organization to the planar tensile mechanics of the human supraspinatus tendon by fitting biaxial tensile data with a structural constitutive model that incorporates a sample-specific angular distribution of nonlinear fibers. Regional samples were tested under several biaxial boundary conditions while simultaneously measuring the collagen fiber orientations via polarized light imaging. The histograms of fiber angles were fit with a von Mises probability distribution and input into a hyperelastic constitutive model incorporating the contributions of the uncrimped fibers. Samples with a wide fiber angle distribution produced greater transverse stresses than more highly aligned samples. The structural model fit the longitudinal stresses well (median R(2) ≥ 0.96) and was validated by successfully predicting the stress response to a mechanical protocol not used for parameter estimation. The transverse stresses were fit less well with greater errors observed for less aligned samples. Sensitivity analyses and relatively affine fiber kinematics suggest that

  5. Exercise-induced changes in triceps surae tendon stiffness and muscle strength affect running economy in humans.

    PubMed

    Albracht, Kirsten; Arampatzis, Adamantios

    2013-06-01

    The purpose of the present study was to investigate whether increased tendon-aponeurosis stiffness and contractile strength of the triceps surae (TS) muscle-tendon units induced by resistance training would affect running economy. Therefore, an exercise group (EG, n = 13) performed a 14-week exercise program, while the control group (CG, n = 13) did not change their training. Maximum isometric voluntary contractile strength and TS tendon-aponeurosis stiffness, running kinematics and fascicle length of the gastrocnemius medialis (GM) muscle during running were analyzed. Furthermore, running economy was determined by measuring the rate of oxygen consumption at two running velocities (3.0, 3.5 ms(-1)). The intervention resulted in a ∼7 % increase in maximum plantarflexion muscle strength and a ∼16 % increase in TS tendon-aponeurosis stiffness. The EG showed a significant ∼4 % reduction in the rate of oxygen consumption and energy cost, indicating a significant increase in running economy, while the CG showed no changes. Neither kinematics nor fascicle length and elongation of the series-elastic element (SEE) during running were affected by the intervention. The unaffected SEE elongation of the GM during the stance phase of running, in spite of a higher tendon-aponeurosis stiffness, is indicative of greater energy storage and return and a redistribution of muscular output within the lower extremities while running after the intervention, which might explain the improved running economy.

  6. Unexpected Fascicle Length Changes In Denervated Feline Soleus Muscle During Stance Phase Of Walking

    PubMed Central

    Mehta, Ricky; Maas, Huub; Gregor, Robert J.; Prilutsky, Boris I.

    2015-01-01

    After surgical repair of traumatically severed peripheral nerves, associated muscles are paralyzed for weeks. Little is known about fascicle length changes in paralyzed muscles during locomotion. The aim of this study was to investigate to what extent, if any, muscle fascicles of denervated feline soleus (SO) change length during stance of walking when intact SO synergists are actively contracting. Hindlimb kinematics, SO fascicle and muscle-tendon unit (MTU) length, and EMG activity of SO, lateral gastrocnemius (LG) and medial gastrocnemius (MG) were measured during level and slope walking in adult cats. Measurements were taken before and 1–2 weeks following SO-LG denervation. Unexpectedly, SO fascicle lengthening and shortening during stance in all walking conditions were evident after denervation. The greatest SO fascicle shortening (17.3 ± 2.2% of a reference length) and least fascicle lengthening (1.5 ± 0.8%) after denervation were found during upslope walking, where MG EMG activity was greatest across slopes (P < 0.05) and greatest discrepancies between post denervation SO fascicle and MTU length changes occurred. These findings suggest that myofascial linkages between denervated SO and its active synergists might affect its fascicle length changes. Further studies are needed to directly test this suggestion. PMID:26635206

  7. The role of human ankle plantar flexor muscle-tendon interaction and architecture in maximal vertical jumping examined in vivo.

    PubMed

    Farris, Dominic James; Lichtwark, Glen A; Brown, Nicholas A T; Cresswell, Andrew G

    2016-02-01

    Humans utilise elastic tendons of lower limb muscles to store and return energy during walking, running and jumping. Anuran and insect species use skeletal structures and/or dynamics in conjunction with similarly compliant structures to amplify muscle power output during jumping. We sought to examine whether human jumpers use similar mechanisms to aid elastic energy usage in the plantar flexor muscles during maximal vertical jumping. Ten male athletes performed maximal vertical squat jumps. Three-dimensional motion capture and a musculoskeletal model were used to determine lower limb kinematics that were combined with ground reaction force data in an inverse dynamics analysis. B-mode ultrasound imaging of the lateral gastrocnemius (GAS) and soleus (SOL) muscles was used to measure muscle fascicle lengths and pennation angles during jumping. Our results highlighted that both GAS and SOL utilised stretch and recoil of their series elastic elements (SEEs) in a catapult-like fashion, which likely serves to maximise ankle joint power. The resistance of supporting of body weight allowed initial stretch of both GAS and SOL SEEs. A proximal-to-distal sequence of joint moments and decreasing effective mechanical advantage early in the extension phase of the jumping movement were observed. This facilitated a further stretch of the SEE of the biarticular GAS and delayed recoil of the SOL SEE. However, effective mechanical advantage did not increase late in the jump to aid recoil of elastic tissues.

  8. Effect of muscle contraction levels on the force-length relationship of the human Achilles tendon during lengthening of the triceps surae muscle-tendon unit.

    PubMed

    Sugisaki, Norihide; Kawakami, Yasuo; Kanehisa, Hiroaki; Fukunaga, Tetsuo

    2011-07-28

    Findings from animal experiments are sometimes contradictory to the idea that the tendon structure is a simple elastic spring in series with muscle fibers, and suggest influence of muscle contraction on the tendon mechanical properties. The purpose of the present study was to investigate the influence of muscle contraction levels on the force-length relationship of the human Achilles tendon during lengthening of the triceps surae muscle-tendon unit. For seven subjects, ankle dorsiflexion was performed without (passive condition) and with contraction of plantar flexor muscles (eccentric conditions, at 3 contraction levels) on an isokinetic dynamometer. Deformation of the Achilles tendon during each trial was measured using ultrasonography. The Achilles tendon force corresponding to the tendon elongation of 10mm in the passive condition was significantly smaller than those in the eccentric conditions (p<0.05 or p<0.01). Within the eccentric conditions, the Achilles tendon force corresponding to the tendon elongation of 10mm was significantly greater in the maximal contraction level than those in submaximal eccentric conditions (p<0.05 or p<0.01). In addition, the tendon stiffness was greater in higher contraction levels (p<0.05 or p<0.01). Present results suggest that the human tendon structure is not a simple elastic spring in series with muscle fibers.

  9. Microstructural stress relaxation mechanics in functionally different tendons.

    PubMed

    Screen, H R C; Toorani, S; Shelton, J C

    2013-01-01

    Tendons experience widely varying loading conditions in vivo. They may be categorised by their function as either positional tendons, which are used for intricate movements and experience lower stress, or as energy storage tendons which act as highly stressed springs during locomotion. Structural and compositional differences between tendons are thought to enable an optimisation of their properties to suit their functional environment. However, little is known about structure-function relationships in tendon. This study adopts porcine flexor and extensor tendon fascicles as examples of high stress and low stress tendons, comparing their mechanical behaviour at the micro-level in order to understand their stress relaxation response. Stress-relaxation was shown to occur predominantly through sliding between collagen fibres. However, in the more highly stressed flexor tendon fascicles, more fibre reorganisation was evident when the tissue was exposed to low strains. By contrast, the low load extensor tendon fascicles appears to have less capacity for fibre reorganisation or shearing than the energy storage tendon, relying more heavily on fibril level relaxation. The extensor fascicles were also unable to sustain loads without rapid and complete stress relaxation. These findings highlight the need to optimise tendon repair solutions for specific tendons, and match tendon properties when using grafts in tendon repairs.

  10. 3D fascicle orientations in triceps surae.

    PubMed

    Rana, Manku; Hamarneh, Ghassan; Wakeling, James M

    2013-07-01

    The aim of this study was to determine the three-dimensional (3D) muscle fascicle architecture in human triceps surae muscles at different contraction levels and muscle lengths. Six male subjects were tested for three contraction levels (0, 30, and 60% of maximal voluntary contraction) and four ankle angles (-15, 0, 15, and 30° of plantar flexion), and the muscles were imaged with B-mode ultrasound coupled to 3D position sensors. 3D fascicle orientations were represented in terms of pennation angle relative to the major axis of the muscle and azimuthal angle (a new architectural parameter introduced in this study representing the radial angle around the major axis). 3D orientations of the fascicles, and the sheets along which they lie, were regionalized in all the three muscles (medial and lateral gastrocnemius and the soleus) and changed significantly with contraction level and ankle angle. Changes in the azimuthal angle were of similar magnitude to the changes in pennation angle. The 3D information was used for an error analysis to determine the errors in predictions of pennation that would occur in purely two-dimensional studies. A comparison was made for assessing pennation in the same plane for different contraction levels, or for adjusting the scanning plane orientation for different contractions: there was no significant difference between the two simulated scanning conditions for the gastrocnemii; however, a significant difference of 4.5° was obtained for the soleus. Correct probe orientation is thus more critical during estimations of pennation for the soleus than the gastrocnemii due to its more complex fascicle arrangement.

  11. Lovastatin-Mediated Changes in Human Tendon Cells.

    PubMed

    Kuzma-Kuzniarska, Maria; Cornell, Hannah R; Moneke, Michael C; Carr, Andrew J; Hulley, Philippa A

    2015-10-01

    Statins are among the most widely prescribed drugs worldwide. Numerous studies have shown their beneficial effects in prevention of cardiovascular disease through cholesterol-lowering and anti-atherosclerotic properties. Although some statin patients may experience muscle-related symptoms, severe side effects of statin therapy are rare, primarily due to extensive first-pass metabolism in the liver. Skeletal muscles appear to be the main site of side effects; however, recently some statin-related adverse effects have been described in tendon. The mechanism behind these side effects remains unknown. This is the first study that explores tendon-specific effects of statins in human primary tenocytes. The cells were cultured with different concentrations of lovastatin for up to 1 week. No changes in cell viability or morphology were observed in tenocytes incubated with therapeutic doses. Short-term exposure to lovastatin concentrations outside the therapeutic range had no effect on tenocyte viability; however, cell migration was reduced. Simvastatin and atorvastatin, two other drug family members, also reduced the migratory properties of the cells. Prolonged exposure to high concentrations of lovastatin induced changes in cytoskeleton leading to cell rounding and decreased levels of mRNA for matrix proteins, but increased BMP-2 expression. Gap junctional communication was impaired but due to cell shape change and separation rather than direct gap junction inhibition. These effects were accompanied by inhibition of prenylation of Rap1a small GTPase. Collectively, we showed that statins in a dose-dependent manner decrease migration of human tendon cells, alter their expression profile and impair the functional network, but do not inhibit gap junction function.

  12. Strain and elongation of the human gastrocnemius tendon and aponeurosis during maximal plantarflexion effort.

    PubMed

    Arampatzis, A; Stafilidis, S; DeMonte, G; Karamanidis, K; Morey-Klapsing, G; Brüggemann, G P

    2005-04-01

    Regarding the strain and elongation distribution along the tendon and aponeurosis the literature is reporting different findings. Therefore, the purpose of this study was to examine in vivo the elongation and the strain of the human gastrocnemius medialis tendon and aponeurosis simultaneously at the same trial during maximal voluntary plantarflexion efforts. Twelve subjects participated in the study. The subjects performed isometric maximal voluntary contractions of their left leg on a Biodex-dynamometer. The kinematics of the leg were recorded using the Vicon 624 system with 8 cameras operating at 120 Hz. Two ultrasound probes were used to visualise the tendon (myotendinous junction region) and the distal aponeurosis of the gastrocnemius medialis respectively. The main findings were: (a) the absolute elongation of the gastrocnemius medialis tendon was different to that of the aponeurosis, (b) the strain of the gastrocnemius medialis tendon did not differ from the strain of the aponeurosis, (c) during the "isometric" plantarflexion the ankle angle exhibited significant changes, and (d) the non-rigidity of the dynamometer arm-foot system and the coactivity of the tibialis anterior both have a significant influence on the moment exerted at the ankle joint. Thus the strain of the human gastrocnemius medialis tendon and aponeurosis estimated in vivo using two-dimensional ultrasonography is uniform. To calculate the elongation of the whole tendon it is necessary to multiply the strain calculated for the examined part of the tendon by the total length of the tendon.

  13. Tendon degeneration and chronic shoulder pain: changes in the collagen composition of the human rotator cuff tendons in rotator cuff tendinitis.

    PubMed Central

    Riley, G P; Harrall, R L; Constant, C R; Chard, M D; Cawston, T E; Hazleman, B L

    1994-01-01

    OBJECTIVES--To analyse the collagen composition of normal adult human supraspinatus tendon and to compare with: (1) a flexor tendon (the common biceps tendon) which is rarely involved in any degenerative pathology; (2) degenerate tendons from patients with chronic rotator cuff tendinitis. METHODS--Total collagen content, collagen solubility and collagen type were investigated by hydroxyproline analysis, acetic acid and pepsin digestion, cyanogen bromide peptide analysis, SDS-PAGE and Western blotting. RESULTS--The collagen content of the normal cadaver supraspinatus tendons (n = 60) was 96.3 micrograms HYPRO/mg dry weight (range 79.3-113.3) and there was no significant change across the age range 11 to 95 years. There was no significant difference from the common biceps tendon [93.3 (13.5) micrograms HYPRO/mg dry weight, n = 24]. Although extremely insoluble in both acetic acid and pepsin, much of the collagen was soluble after cyanogen bromide digestion [mean 47.9% (29.8)]. Seventeen per cent (10/60) of the 'normal' cadaver supraspinatus tendon sample contained more than 5% type III collagen, although none of the common biceps tendons had significant amounts. Degenerate supraspinatus and subscapularis tendons had a reduced collagen content [83.8 (13.9) micrograms/mg dry weight and 76.9 (16.8) micrograms/mg dry wt respectively) and were more soluble in acetic acid, pepsin and cyanogen bromide (p < 0.001). Eighty two per cent (14/17) of supraspinatus tendons and 100% (8/8) of subscapularis tendons from patients with tendinitis contained more than 5% type III collagen. CONCLUSIONS--The changes in collagen composition in rotator cuff tendinitis are consistent with new matrix synthesis, tissue remodelling and wound healing, in an attempt to repair the tendon defect, even in old and degenerate tendons. An increase in type III collagen in some 'normal' cadaver supraspinatus tendons is evidence that changes in collagen synthesis and turnover may precede tendon rupture

  14. Lack of tissue renewal in human adult Achilles tendon is revealed by nuclear bomb (14)C.

    PubMed

    Heinemeier, Katja Maria; Schjerling, Peter; Heinemeier, Jan; Magnusson, Stig Peter; Kjaer, Michael

    2013-05-01

    Tendons are often injured and heal poorly. Whether this is caused by a slow tissue turnover is unknown, since existing data provide diverging estimates of tendon protein half-life that range from 2 mo to 200 yr. With the purpose of determining life-long turnover of human tendon tissue, we used the (14)C bomb-pulse method. This method takes advantage of the dramatic increase in atmospheric levels of (14)C, produced by nuclear bomb tests in 1955-1963, which is reflected in all living organisms. Levels of (14)C were measured in 28 forensic samples of Achilles tendon core and 4 skeletal muscle samples (donor birth years 1945-1983) with accelerator mass spectrometry (AMS) and compared to known atmospheric levels to estimate tissue turnover. We found that Achilles tendon tissue retained levels of (14)C corresponding to atmospheric levels several decades before tissue sampling, demonstrating a very limited tissue turnover. The tendon concentrations of (14)C approximately reflected the atmospheric levels present during the first 17 yr of life, indicating that the tendon core is formed during height growth and is essentially not renewed thereafter. In contrast, (14)C levels in muscle indicated continuous turnover. Our observation provides a fundamental premise for understanding tendon function and pathology, and likely explains the poor regenerative capacity of tendon tissue.

  15. Inflammation activation and resolution in human tendon disease

    PubMed Central

    Dakin, Stephanie G; Martinez, Fernando O; Yapp, Clarence; Wells, Graham; Oppermann, Udo; Dean, Benjamin JF; Smith, Richard DJ; Wheway, Kim; Watkins, Bridget; Roche, Lucy; Carr, Andrew J

    2016-01-01

    Improved understanding of the role of inflammation in tendon disease is required to facilitate therapeutic target discovery. We studied supraspinatus tendons from patients experiencing pain before and after surgical subacromial decompression treatment. Tendons were classified as having early, intermediate or advanced disease and inflammation was characterized through activation of pathways mediated by Interferon, NF-κB, glucocorticoid receptor and STAT-6. Inflammation signatures revealed expression of genes and proteins induced by Interferon and NF-κB in early stage disease and genes and proteins induced by STAT-6 and glucocorticoid receptor activation in advanced stage disease. The pro-resolving proteins FPR2/ALX and ChemR23 were increased in early stage disease compared to intermediate-advanced stage disease. Patients who were pain-free post-treatment had tendons with increased expression of CD206 and ALOX15 mRNA compared to tendons from patients who continued to experience pain post-treatment, suggesting that these genes and their pathways may moderate tendon pain. Stromal cells from diseased tendons cultured in vitro showed increased expression of NF-κB and Interferon target genes after treatment with lipopolysaccharide or IFNγ compared to stromal cells derived from healthy tendons. We identified 15-epi Lipoxin A4, a stable lipoxin metabolite derived from aspirin treatment, as potentially beneficial in the resolution of tendon inflammation. PMID:26511510

  16. Distribution and expression of type VI collagen and elastic fibers in human rotator cuff tendon tears.

    PubMed

    Thakkar, Dipti; Grant, Tyler M; Hakimi, Osnat; Carr, Andrew J

    2014-01-01

    There is increasing evidence for a progressive extracellular matrix change in rotator cuff disease progression. Directly surrounding the cell is the pericellular matrix, where assembly of matrix aggregates typically occurs making it critical in the response of tendon cells to pathological conditions. Studies in animal models have identified type VI collagen, fibrillin-1 and elastin to be located in the pericellular matrix of tendon and contribute in maintaining the structural and biomechanical integrity of tendon. However, there have been no reports on the localization of these proteins in human tendon biopsies. This study aimed to characterize the distribution of these ECM components in human rotator cuffs and gain greater insight into the relationship of pathology to tear size by analyzing the distribution and expression profiles of these ECM components. Confocal microscopy confirmed the localization of these structural molecules in the pericellular matrix of the human rotator cuff. Tendon degeneration led to an increased visibility of these components with a significant disorganization in the distribution of type VI collagen. At the genetic level, an increase in tear size was linked to an increased transcription of type VI collagen and fibrillin-1 with no significant alteration in the elastin levels. This is the first study to confirm the localization of type VI collagen, elastin and fibrillin-1 in the pericellular region of human supraspinatus tendon and assesses the effect of tendon degeneration on these structures, thus providing a useful insight into the composition of human rotator cuff tears which can be instrumental in predicting disease prognosis.

  17. A novel diffusion-tensor MRI approach for skeletal muscle fascicle length measurements.

    PubMed

    Oudeman, Jos; Mazzoli, Valentina; Marra, Marco A; Nicolay, Klaas; Maas, Mario; Verdonschot, Nico; Sprengers, Andre M; Nederveen, Aart J; Strijkers, Gustav J; Froeling, Martijn

    2016-12-01

    Musculoskeletal (dys-)function relies for a large part on muscle architecture which can be obtained using Diffusion-Tensor MRI (DT-MRI) and fiber tractography. However, reconstructed tracts often continue along the tendon or aponeurosis when using conventional methods, thus overestimating fascicle lengths. In this study, we propose a new method for semiautomatic segmentation of tendinous tissue using tract density (TD). We investigated the feasibility and repeatability of this method to quantify the mean fascicle length per muscle. Additionally, we examined whether the method facilitates measuring changes in fascicle length of lower leg muscles with different foot positions. Five healthy subjects underwent two DT-MRI scans of the right lower leg, with the foot in 15° dorsiflexion, neutral, and 30° plantarflexion positions. Repeatability of fascicle length measurements was assessed using Bland-Altman analysis. Changes in fascicle lengths between the foot positions were tested using a repeated multivariate analysis of variance (MANOVA). Bland-Altman analysis showed good agreement between repeated measurements. The coefficients of variation in neutral position were 8.3, 16.7, 11.2, and 10.4% for soleus (SOL), fibularis longus (FL), extensor digitorum longus (EDL), and tibialis anterior (TA), respectively. The plantarflexors (SOL and FL) showed significant increase in fascicle length from plantarflexion to dorsiflexion, whereas the dorsiflexors (EDL and TA) exhibited a significant decrease. The use of a tract density for semiautomatic segmentation of tendinous structures provides more accurate estimates of the mean fascicle length than traditional fiber tractography methods. The method shows moderate to good repeatability and allows for quantification of changes in fascicle lengths due to passive stretch.

  18. Strain and elongation of the human semitendinosus muscle - tendon unit.

    PubMed

    Kellis, Eleftherios; Patsika, Glykeria; Karagiannidis, Evaggelos

    2013-12-01

    The semitendinosus (ST) consists of a long distal tendon and it is divided in two parts by a tendinous inscription (TI). The purpose of this study was to quantify strain and elongation of the TI and the distal tendon of ST. Fourteen subjects performed ramp isometric contractions of the knee flexors at 0°, 45° and 90° of knee flexion. Two ultrasound probes were used to visualize the displacement of the distal tendon and selected points across the TI and aponeuroses. Three-way analysis of variance designs indicated that: (a) strain and elongation of the ST distal muscle-tendon junction were higher than that of the aponeurosis - TI junction points (p < 0.05) (b) the long arm of the TI reach strain of 49.86 ± 7.77% which was significantly (p < 0.05) higher than that displayed by the short arm (28.35 ± 0.59%) (c) Strain of tendinous and TI-aponeuroses segments significantly increased from 90° to 0° of knee flexion while the inverse was observed for the TI arm length (p < 0.05). (d) Tendon strain was significantly higher than strain of the TI-aponeuroses segments at 45° and 90° of knee flexion while the opposite was observed at 0° of knee flexion. The arrangement of TI along ST length results in differential local strains, indicating that the mechanical properties of the ST muscle are affected by tendon, aponeuroses and tendinous inscription interactions.

  19. Mechanical properties of tendon and aponeurosis of human gastrocnemius muscle in vivo.

    PubMed

    Muramatsu, T; Muraoka, T; Takeshita, D; Kawakami, Y; Hirano, Y; Fukunaga, T

    2001-05-01

    Load-strain characteristics of tendinous tissues (Achilles tendon and aponeurosis) were determined in vivo for human medial gastrocnemius (MG) muscle. Seven male subjects exerted isometric plantar flexion torque while the elongation of tendinous tissues of MG was determined from the tendinous movements by using ultrasonography. The maximal strain of the Achilles tendon and aponeurosis, estimated separately from the elongation data, was 5.1 +/- 1.1 and 5.9 +/- 1.6%, respectively. There was no significant difference in strain between the Achilles tendon and aponeurosis. In addition, no significant difference in strain was observed between the proximal and distal regions of the aponeurosis. The results indicate that tendinous tissues of the MG are homogeneously stretched along their lengths by muscle contraction, which has functional implications for the operation of the human MG muscle-tendon unit in vivo.

  20. Variation in the human Achilles tendon moment arm during walking.

    PubMed

    Rasske, Kristen; Thelen, Darryl G; Franz, Jason R

    2017-02-01

    The Achilles tendon (AT) moment arm is an important determinant of ankle moment and power generation during locomotion. Load and depth-dependent variations in the AT moment arm are generally not considered, but may be relevant given the complex triceps surae architecture. We coupled motion analysis and ultrasound imaging to characterize AT moment arms during walking in 10 subjects. Muscle loading during push-off amplified the AT moment arm by 10% relative to heel strike. AT moment arms also varied by 14% over the tendon thickness. In walking, AT moment arms are not strictly dependent on kinematics, but exhibit important load and spatial dependencies.

  1. Distinct muscle fascicle length changes in feline medial gastrocnemius and soleus muscles during slope walking.

    PubMed

    Maas, Huub; Gregor, Robert J; Hodson-Tole, Emma F; Farrell, Brad J; Prilutsky, Boris I

    2009-04-01

    On the basis of differences in physiology, e.g., histochemical properties and spindle density, and the structural design of the cat soleus (SO) and medial gastrocnemius (MG) muscles, we hypothesized that 1) fascicle length changes during overground walking would be both muscle and slope dependent, which would have implications for the muscles' force output as well as sensory function, and that 2) muscle-tendon unit (MTU) and fascicle length changes would be different, in which case MTU length could not be used as an indicator of muscle spindle strain. To test these hypotheses, we quantified muscle fascicle length changes and compared them with length changes of the whole MTU in the SO and MG during overground walking at various slopes (0, +/- 25, +/- 50, +75, and +100%). The SO and MG were surgically instrumented with sonomicrometry crystals and fine-wire electromyogram electrodes to measure changes in muscle fascicle length and muscle activity, respectively. MTU lengths were calculated using recorded ankle and knee joint angles and a geometric model of the hindlimb. The resultant joint moments were calculated using inverse dynamics analysis to infer muscle loading. It was found that although MTU length and velocity profiles of the SO and MG appeared similar, length changes and velocities of muscle fascicles were substantially different between the two muscles. Fascicle length changes of both SO and MG were significantly affected by slope intensity acting eccentrically in downslope walking (-25 to -50%) and concentrically in upslope walking (+25 to +100%). The differences in MTU and fascicle behaviors in both the SO and MG muscles during slope walking were explained by the three distinct features of these muscles: 1) the number of joints spanned, 2) the pennation angle, and 3) the in-series elastic component. It was further suggested that the potential role of length feedback from muscle spindles is both task and muscle dependent.

  2. Torn human rotator cuff tendons have reduced collagen thermal properties on differential scanning calorimetry.

    PubMed

    Chaudhury, Salma; Holland, Christopher; Porter, David; Tirlapur, Uday K; Vollrath, Fritz; Carr, Andrew J

    2011-12-01

    The cause of the high failure rates often observed following rotator cuff tendon repairs, particularly massive tears, is not fully understood. Collagen structural changes have been shown to alter tendon thermal and mechanical properties. This study aimed to form a quantitative rather than qualitative assessment, of whether differences in collagen structure and integrity existed between small biopsies of normal, small, and massive rotator cuff tears using differential scanning calorimetry. Thermal properties were measured for 28 human biopsies taken intra-operatively from normal, small, and massive rotator cuff tendon tears in this powered study. Denaturation temperatures are represented by T(onset) (°C) and T(peak) (°C). The T(onset) is proposed to represent water-amide hydrogen bond breakage and resulting protein backbone mobility. T(peak) reportedly corresponds to the temperature at which the majority of proteins fall out of solution. Denaturation enthalpy (ΔH) should correlate with the amount of triple helical structure that is denatured. Fluorescence and confocal microscopy allowed quantitative validation. Small and massive rotator cuff tears had significantly higher T(onset), T(peak), and ΔH compared to controls. Polarized light microscopy of torn tendons confirmed greater collagen structural disruption compared to controls. These novel findings suggest greater quantifiable collagen structural disruption in rotator cuff tears, compared to controls. This study offers insight into possible mechanisms for the reduced strength of torn tendons and may explain why repaired tendons fail to heal.

  3. Length change of human gastrocnemius aponeurosis and tendon during passive joint motion.

    PubMed

    Muraoka, Tetsuro; Muramatsu, Tadashi; Takeshita, Daisuke; Kawakami, Yasuo; Fukunaga, Tetsuo

    2002-01-01

    The extent of elongation and slackness of aponeurosis and tendon, and muscle fiber length of human medial gastrocnemius muscle are determined in vivo using ultrasonography. The ankle joint is passively moved at 5 degrees /s within the joint range of -36 to 7 degrees (0 degrees = neutral anatomic position; positive values for dorsiflexion) by a dynamometer while the length change of the aponeurosis and tendon is determined using ultrasonography (n = 8 men). Strain is calculated as the length change relative to the reference length of aponeurosis and tendon when the passive joint moment is 0. Elongation (positive strain values) of aponeurosis and tendon at 7 degrees are 2.1 +/- 1.1 and 2.4 +/- 1.0%, respectively. The extent of slackness (negative strain values) of aponeurosis and tendon at -36 degrees are -1.8 +/- 1.1 and -3.5 +/- 1.6%, respectively, and there is a significant difference between them (p < 0.05). This may be related to the existence of muscle fibers that attach to the aponeurosis over its whole length and do not allow it to fold. The results indicate that the length change of aponeurosis and tendon of medial gastrocnemius muscle occurs over the range of ankle joint positions even during passive joint motions.

  4. Modeling the tensile behavior of human Achilles tendon.

    PubMed

    Lewis, G; Shaw, K M

    1997-01-01

    Uniaxial quasi-static tensile stress, sigma versus strain, epsilon, data were obtained from 29 cadaveric Achilles tendons (donor ages: 36 to 100 years), at a strain rate of either 10 or 100%/s. These results were then used in modeling the elastic component of the tensile deformational behavior of this tissue. Two approaches were taken. In the first, it was shown that the following constitutive relation provided an excellent fit to the elastic section of the sigma-epsilon curve, sigma = C epsilon exp[D epsilon + F epsilon 2], with C, D and F being material constants, whose values for the present dataset were found to be C = 2.00 +/- 0.99, D = 0.089 +/- 0.087 and F = -0.0047 +/- 0.0095. The values of these coefficients were not statistically significantly affected by either donor age or test strain rate. In the second approach, the value of the modulus of elasticity of a filamentary polymer matrix composite material was computed as a function of various combinations of values of the modulus of elasticity of the fiber, the modulus of elasticity of the matrix, and angle of orientation of the principal material axes with respect to the reference coordinate axes (theta) for a fiber volume fraction of 0.6 and a material Poisson's ratio of 0.4. By comparing these results with the experimentally-obtained values of the tangent modulus of elasticity of the tendons (defined as the slope of the linear section of the post-toe zone in the sigma-epsilon plot), and assuming that the tendon may be idealized as a filamentary polymer matrix composite material, the suggestion is made that the winding angle of the fibers (collagen fibrils) in the tendon (taken to be equal to theta) is about 6 degrees.

  5. Mechanical properties of radiation-sterilised human Bone-Tendon-Bone grafts preserved by different methods.

    PubMed

    Kamiński, A; Gut, G; Marowska, J; Lada-Kozłowska, M; Biwejnis, W; Zasacka, M

    2009-08-01

    Patellar tendon auto- and allo-grafts are commonly used in orthopedic surgery for reconstruction of the anterior cruciate ligaments (ACL). Autografts are mainly used for primary reconstruction, while allografts are useful for revision surgery. To avoid the risk of infectious disease transmission allografts should be radiation-sterilised. As radiation-sterilisation supposedly decreases the mechanical strength of tendon it is important to establish methods of allograft preservation and sterilisation assuring the best quality of grafts and their safety at the same time. Therefore, the purpose of this study was to compare the tensile strength of human patellar tendon (cut out as for ACL reconstruction), preserved by various methods (deep fresh freezing, glycerolisation, lyophilisation) and subsequently radiation-sterilised with doses of 0, 25, 50 or 100 kGy. Bone-Tendon-Bone grafts (BTB) were prepared from cadaveric human patella tendons with both patellar and tibial attachments. BTB grafts were preserved by deep freezing, glycerolisation or lyophilisation and were subsequently radiation-sterilised with doses of 0 (control), 25, 50 or 100 kGy. All samples were subjected to mechanical failure tensile tests with the use of Instron system in order to estimate their mechanical properties. All lyophilised grafts were rehydrated before performing of those tests. Obtained mechanical tests results of examined grafts suggest that deep-frozen irradiated grafts retain their initial mechanical properties to an extent which does not exclude their clinical application.

  6. Development of the human Achilles tendon enthesis organ.

    PubMed

    Shaw, H M; Vázquez, Osorio T; McGonagle, D; Bydder, G; Santer, R M; Benjamin, M

    2008-12-01

    The attachment of the Achilles tendon is part of an 'enthesis organ' that reduces stress concentration at the hard-soft tissue interface. The organ also includes opposing sesamoid and periosteal fibrocartilages, a bursa and Kager's fat pad. In addition, the deep crural and plantar fasciae contribute to Achilles stress dissipation and could also be regarded as components. Here we describe the sequence in which these various tissues differentiate. Serial sections of feet from spontaneously aborted foetuses (crown rump lengths 22-322 mm) were examined. All slides formed part of an existing collection of histologically sectioned embryological material, obtained under Spanish law and housed in the Universidad Complutense, Madrid. From the earliest stages, it was evident that the Achilles tendon and plantar fascia had a mutual attachment to the calcaneal perichondrium. The first components of the enthesis organ to appear (in the 45-mm foetus) were the retrocalcaneal bursa and the crural fascia. The former developed by cavitation within the mesenchyme that later gave rise to Kager's fat pad. The tip of the putative fat pad protruded into the developing bursa in the 110-mm foetus and fully differentiated adipocytes were apparent in the 17-mm foetus. All three fibrocartilages were first recognisable in the 332-mm foetus--at which time adipogenesis had commenced in the heel fat pad. The sequence in which the various elements became apparent suggests that bursal formation and the appearance of the crural fascia may be necessary to facilitate the foot movements that subsequently lead to fibrocartilage differentiation. The later commencement of adipogenesis in the heel than in Kager's pad probably reflects the non-weight environment in utero. The direct continuity between plantar fascia and Achilles tendon that is characteristic of the adult reflects the initial attachment of both structures to the calcaneal perichondrium rather than to the skeletal anlagen itself.

  7. Growth changes in morphological and mechanical properties of human patellar tendon in vivo.

    PubMed

    Kubo, Keitaro; Teshima, Takanori; Hirose, Norikazu; Tsunoda, Naoya

    2014-06-01

    The purpose of this study was to compare the morphological and mechanical properties of the human patellar tendon among elementary school children (prepubertal), junior high school students (pubertal), and adults. Twenty-one elementary school children, 18 junior high school students, and 22 adults participated in this study. The maximal strain, stiffness, Young's modulus, hysteresis, and cross-sectional area of the patellar tendon were measured using ultrasonography. No significant difference was observed in the relative length (to thigh length) or cross-sectional area (to body mass(2/3)) of the patellar tendon among the three groups. Stiffness and Young's modulus were significantly lower in elementary school children than in the other groups, while no significant differences were observed between junior high school students and adults. No significant differences were observed in maximal strain or hysteresis among the three groups. These results suggest that the material property (Young's modulus) of the patellar tendons of elementary school children was lower than that of the other groups, whereas that of junior high school students was already similar to that of adults. In addition, no significant differences were observed in the extensibility (maximal strain) or viscosity (hysteresis) of the patellar tendon among the three groups.

  8. Effect of strength training on human patella tendon mechanical properties of older individuals

    PubMed Central

    Reeves, N D; Maganaris, C N; Narici, M V

    2003-01-01

    This study investigated the effect of strength training on the mechanical properties of the human patella tendon of older individuals. Subjects were assigned to training (n = 9; age 74.3 ± 3.5 years, body mass 69.7 ± 14.8 kg and height 163.4 ± 9.1 cm, mean ±s.d.) and control (n = 9; age 67.1 ± 2 years, body mass 73.5 ± 14.9 kg and height 168.3 ± 11.5 cm) groups. Strength training (two series of 10 repetitions at 80 % of five-repetition maximum) was performed three times per week for 14 weeks using leg extension and leg press exercises. Measurements of tendon elongation during a ramp isometric knee extension were performed before and after training and control periods in vivo using ultrasonography. Training caused a decreased tendon elongation and strain at all levels of force and stress (P < 0.01). Baseline tendon elongation and strain at maximal tendon load were 4.7 ± 1.1 mm and 9.9 ± 2.2 %, respectively (maximum force: 3346 ± 1168 N; maximum stress: 40 ± 11 MPa). After training, these values decreased to 2.9 ± 1.2 mm and 5.9 ± 2.4 % (P < 0.01), respectively (maximum force: 3555 ± 1257 N; maximum stress: 42 ± 11 MPa). Tendon stiffness increased by 65 % (2187 ± 713 to 3609 ± 1220 N mm−1; P < 0.05) and Young's modulus increased by 69 % (1.3 ± 0.3 to 2.2 ± 0.8 GPa; P < 0.01). As a result of these changes, the rate of torque development increased by 27 % (482.8 ± 302.5 to 612.6 ± 401 N m s−1; P < 0.01) following training. No significant changes occurred in any measured variables in the control group (P > 0.05). This study shows for the first time that strength training in old age increases the stiffness and Young's modulus of human tendons. This may reduce the risk of tendon injury in old age and has implications for contractile force production and the rapid execution of motor tasks. PMID:12626673

  9. Ultrasound Elasticity Imaging for Determining the Mechanical Properties of Human Posterior Tibial Tendon: A Cadaveric Study

    PubMed Central

    Yuan, Justin S.; Heden, Gregory J.; Szivek, John A.; Taljanovic, Mihra S.; Latt, L. Daniel; Witte, Russell S.

    2016-01-01

    Posterior tibial tendon dysfunction (PTTD) is a common degenerative condition leading to a severe impairment of gait. There is currently no effective method to determine whether a patient with advanced PTTD would benefit from several months of bracing and physical therapy or ultimately require surgery. Tendon degeneration is closely associated with irreversible degradation of its collagen structure, leading to changes to its mechanical properties. If these properties could be monitored in vivo, they could be used to quantify the severity of tendonosis and help determine the appropriate treatment. The goal of this cadaveric study was, therefore, to develop and validate ultrasound elasticity imaging (UEI) as a potentially noninvasive technique for quantifying tendon mechanical properties. Five human cadaver feet were mounted in a materials testing system (MTS), while the posterior tibial tendon (PTT) was attached to a force actuator. A portable ultrasound scanner collected 2-D data during loading cycles. Young’s modulus was calculated from the strain, loading force, and cross-sectional area of the PTT. Average Young’s modulus for the five tendons was (0.45 ± 0.16 GPa) using UEI, which was consistent with simultaneous measurements made by the MTS across the whole tendon (0.52 ± 0.18 GPa). We also calculated the scaling factor (0.12 ± 0.01) between the load on the PTT and the inversion force at the forefoot, a measurable quantity in vivo. This study suggests that UEI could be a reliable in vivo technique for estimating the mechanical properties of the PTT, and as a clinical tool, help guide treatment decisions for advanced PTTD and other tendinopathies. PMID:25532163

  10. Comparison of elasticity of human tendon and aponeurosis in knee extensors and ankle plantar flexors in vivo.

    PubMed

    Kubo, Keitaro; Kanehisa, Hiroaki; Fukunaga, Tetsuo

    2005-05-01

    The purposes of this study were to compare the elasticity of tendon and aponeurosis in human knee extensors and ankle plantar flexors in vivo and to examine whether the maximal strain of tendon was correlated to that of aponeurosis. The elongation of tendon and aponeurosis during isometric knee extension (n = 23) and ankle plantar flexion (n = 22), respectively, were determined using a real-time ultrasonic apparatus, while the participants performed ramp isometric contractions up to voluntary maximum. To calculate the strain values from the measured elongation, we measured the respective length of tendon and aponeurosis. For the knee extensors, the maximal strain of aponeurosis (12.1 +/- 2.8 %) was significantly greater than that of the patella tendon (8.3 +/- 2.4 %), p < 0.001. On the contrary, the maximal strain of Achilles tendon (5.9 +/- 1.4 %) was significantly greater than that of aponeurosis in ankle plantar flexors (2.7 +/- 1.4 %), p < 0.001. Furthermore, for both knee extensors and ankle plantar flexors there was no significant correlation between maximal strain of tendon and aponeurosis. These results would be important for understanding the different roles of tendon and aponeurosis during human movements and for more accurate muscle modeling.

  11. [Connective tissue reinforcing structures of the digital tendon sheaths of the human hand].

    PubMed

    Knott, C; Schmidt, H M

    1986-01-01

    At a greater number of humid preparated human hands, all the ligamentous supports of the digital tendon sheath were exposed and their dimensions were determined. The osteofibrous channels, which contain the long flexor tendons of the digits, were bounded on the one hand by transversely concave shaft areas of the phalanges and the palmar ligaments and on the other side by the fibrous parts of the tendon sheath. From the second to the 5th finger, it has a regular extension of length, which begins proximal at the heads of the metacarpal bones and runs distal to the base of the nail phalanx. In some cases, there is a continuous communication between the digital tendon sheath of the little finger and the carpal synovial sheath. The tendon sheath of the flexor pollicis longus muscle in comparison with it is always in an open communication with the radial synovial sac of the wrist. At the fibrous supports of the digital tendon sheath, one can find constant and inconstant ligamentous structures. Regular shaped ligaments consist of annular fibers (A1 to A5). The proximal complex of fiber supports is a formation of the A1 and A2 ligaments. The band A1 can be divided into 2 ligaments both of roughly equal length, which lay between the head of the metacarpal bone and the base of the proximal phalanx. The strongest fibrous support of the whole digital tendon sheath represents the band A2. It is attached to the midth of the proximal phalanx and increases in strength from proximal to distal. The middle length varies between 6.7 mm at the thumb and 18.7 mm at the middle finger. The distal margin is strengthened by fibrocartilage tissue to be in accordance with the important function as a pulley. The annular band A4 forms the distal supporting complex height above the shaft of the middle phalanx. At the 2nd to the 5th finger it is, with a middle length of 6 to 7 mm, very much shorter than A2 and restrains first of all the tendon of the flexor digitorum profundus muscle. In the area

  12. Dynamics of goat distal hind limb muscle–tendon function in response to locomotor grade

    PubMed Central

    McGuigan, M. Polly; Yoo, Edwin; Lee, David V.; Biewener, Andrew A.

    2009-01-01

    Summary The functional roles of the lateral gastrocnemius (LG), medial gastrocnemius (MG) and superficial digital flexor (SDF) muscle–tendon units (MTUs) in domestic goats (N=6) were studied as a function of locomotor grade, testing the hypothesis that changes in distal limb muscle work would reflect changes in mechanical work requirements while goats walked or trotted on the level, 15 deg. decline and 15 deg. incline. As steep terrain-adapted animals, changes in muscle work output are expected to be particularly important for goats. In vivo muscle–tendon forces, fascicle length changes and muscle activation were recorded via tendon force buckles, sonomicrometry and electromyography to evaluate the work performance and elastic energy recovery of the three distal MTUs. These recordings confirmed that fascicle strain and force within goat distal hind limb muscles are adjusted in response to changes in mechanical work demand associated with locomotor grade. In general, muscle work was modulated most consistently by changes in fascicle strain, with increased net shortening (P<0.001) observed as goats switched from decline to level to incline locomotion. Peak muscle stresses increased as goats increased speed from a walk to a trot within each grade condition (P<0.05), and also increased significantly with grade (P<0.05 to P<0.01). Due to the increase in net fascicle shortening and muscle force, net muscle work per cycle also increased significantly (P<0.05 to P<0.005) as goats switched from decline to level to incline conditions (LG work: 20 mJ to 56 mJ to 209 mJ; MG work: –7 mJ to 34 mJ to 179 mJ; SDF work: –42 mJ to 14 mJ to 71 mJ, at a 2.5 ms–1 trot). Although muscle work was modulated in response to changes in grade, the amount of work produced by these three distal pennate muscles was small (being <3%) in comparison with the change in mechanical energy required of the limb as a whole. Elastic energy recovery in the SDF and gastrocnemius (GA) tendons was

  13. Cyclic mechanical strain induces NO production in human patellar tendon fibroblasts--a possible role for remodelling and pathological transformation.

    PubMed

    van Griensven, Martijn; Zeichen, Johannes; Skutek, Michael; Barkhausen, Tanja; Krettek, Christian; Bosch, Ulrich

    2003-03-01

    The mechanism by which tendon fibroblasts can detect strain forces and respond to them is fairly unknown. Nitric oxide (NO) is a messenger molecule that among others can respond to shear stress in endothelial cells. Therefore, it was investigated whether cyclic mechanical strain induces NO in vitro in human patellar tendon fibroblasts. Human patellar tendon fibroblasts were cultured from remnants of patellar tendon transplants after reconstructive surgery. Fibroblasts were cultured on elastic silicone dishes. The cells were longitudinally strained (5%, 1 Hz) for 15' or 60'. As a control, no strain was applied. The experiments were finished after 0', 5', 15', and 30'. NO was determined using the Griess reaction. 15' strain showed at 0' and 5' 200% activation, which thereafter at 15' and 30' returned to normal levels. 60' strain showed a biphasic pattern. At 5' and 30', NO levels were increased to 175%. At 15', NO measurement displayed 120% increased levels. Mechanical strain induces NO production by tendon fibroblasts. Therefore, NO produced by tendon fibroblasts, as a response to alteration in their mechanical microenvironment, could modulate fibroblast function. The results of our study suggests that strain-related adaptive changes may, at least in part, be controlled by a process in which strain-related NO production from the fibroblast network may play a pivotal role. Moreover, these are basic findings that are important for further unravelling pathophysiology of tendon diseases.

  14. Reflex responses at the human ankle: the importance of tendon compliance.

    PubMed Central

    Rack, P M; Ross, H F; Thilmann, A F; Walters, D K

    1983-01-01

    Subjects with active stretch reflexes responded to an imposed sinusoidal movement of the ankle joint with a reflex force whose amplitude and timing varied widely with changes in the frequency of movement. At some frequency between 6 and 8 Hz, the reflex force tended to offset the non-reflex component of resistance, and thus to reduce the total resistance to movement. At this frequency the reflex response was particularly vigorous, with a deep modulation of electromyogram (e.m.g.) activity and a displacement of the joint stiffness vectors far from their high frequency values. The total resistance to movement might then be small, or it might be zero, or the reflex might actually assist the movement. As the frequency of movement was decreased through this critical range, the timing of the reflex response to movement changed rapidly with an abrupt advancement of the triceps surae e.m.g. signal, and a wide separation of the joint stiffness vectors as they passed close to the origin. This result was attributed to a changing distribution of the movement between the muscle fibres and an elastic Achilles tendon. It was assumed that at most frequencies the muscle fibres resisted extension, so that a major part of the imposed movement went into stretching the tendon; when, however, at 6-8 Hz, the reflex response was so timed as to reduce or abolish the resistance of the muscle fibres, more of the movement would take place in them. The muscle spindles would 'see' this larger movement of the muscle fibres, and generate correspondingly more reflex activity. A simplified model of the muscle-tendon combination behaves in a way that supports this view, and the available information about the human Achilles tendon indicates that it is sufficiently compliant for such an explanation. Therefore, movements imposed on the ankle joint would not necessarily be 'seen' by the muscle spindles, since they would be modified by transmission through a compliant tendon. By assuming a value for the

  15. New Imaging Methods for Non-invasive Assessment of Mechanical, Structural, and Biochemical Properties of Human Achilles Tendon: A Mini Review

    PubMed Central

    Fouré, Alexandre

    2016-01-01

    The mechanical properties of tendon play a fundamental role to passively transmit forces from muscle to bone, withstand sudden stretches, and act as a mechanical buffer allowing the muscle to work more efficiently. The use of non-invasive imaging methods for the assessment of human tendon's mechanical, structural, and biochemical properties in vivo is relatively young in sports medicine, clinical practice, and basic science. Non-invasive assessment of the tendon properties may enhance the diagnosis of tendon injury and the characterization of recovery treatments. While ultrasonographic imaging is the most popular tool to assess the tendon's structural and indirectly, mechanical properties, ultrasonographic elastography, and ultra-high field magnetic resonance imaging (UHF MRI) have recently emerged as potentially powerful techniques to explore tendon tissues. This paper highlights some methodological cautions associated with conventional ultrasonography and perspectives for in vivo human Achilles tendon assessment using ultrasonographic elastography and UHF MRI. PMID:27512376

  16. Determination of the fascicle length of the gastrocnemius muscle during calf raise exercise using ultrasonography

    PubMed Central

    Kudo, Shintarou; Hisada, Tomoyuki; Sato, Takanori

    2015-01-01

    [Purpose] The purpose of this study was to find a strength training protocol which maintains isometric contraction of the triceps surae during dorsal flexion of the ankle. [Subjects] The left feet of 22 young normal volunteers who did not have orthopedic injuries or lower limb pain participated in this study. [Methods] All subjects performed four sets of five repetitions of four sets calf-raise (CR) exercise at were (1) 60 bpm without a pedestal, (2) 60 bpm with a pedestal, (3) 90 bpm without a pedestal, and (4) 90 bpm with a pedestal. The fascicle length of the lateral head of the gastrocnemius and ankle angle were measured using ultrasonography and a video camera. The CR exercise was divided into two or three phases using the kinematics of the ankle. The average change in fascicle length over the five repetitions of each phase were compared. [Results] The change of the fascicle length during the hyper-dorsiflexion phase was significantly smaller than during the other two phases. [Conclusion] It is possible that eccentric CR exercises have progressed to motor learning of the isometric contraction during counter movement, and improved the release of elastic energy of the Achilles tendon during running, jumping, and other athletic activities. PMID:26834347

  17. Tendonitis (image)

    MedlinePlus

    ... tendon. It can occur as a result of injury, overuse, or with aging as the tendon loses elasticity. Any action that places prolonged repetitive strain on the forearm muscles can cause tendonitis. The ...

  18. The glial fascicle: an ontogenic and phylogenic unit guiding, supplying and distributing mammalian cortical neurons.

    PubMed

    Gressens, P; Evrard, P

    1993-12-17

    Neurons destined for the mammalian neocortex migrate along radial glial cells (RGCs). This paper describes a comparative study of RGCs in the mouse, rat, hamster, cat and human fetus, selected as representative species of mammalian evolution. The glial fascicles display constant features throughout these species: they consist of 4-10 RGCs filled with glycogen. The glial fascicle guides and probably supplies metabolites to the migrating neurons and organizes the vertical lamination of the developing neocortical plate. The neuronal-glial unit which consists of the RGCs and their affiliated migrating neurons is conserved throughout the species studied, suggesting a designation as a phylogenic unit.

  19. Effects of a peracetic acid disinfection protocol on the biocompatibility and biomechanical properties of human patellar tendon allografts.

    PubMed

    Lomas, R J; Jennings, L M; Fisher, J; Kearney, J N

    2004-01-01

    Patellar tendon allografts, retrieved from cadaveric human donors, are widely used for replacement of damaged cruciate ligaments. In common with other tissue allografts originating from cadaveric donors, there are concerns regarding the potential for disease transmission from the donor to the recipient. Additionally, retrieval and subsequent processing protocols expose the graft to the risk of environmental contamination. For these reasons, disinfection or sterilisation protocols are necessary for these grafts before they are used clinically. A high-level disinfection protocol, utilising peracetic acid (PAA), has been developed and investigated for its effects on the biocompatibility and biomechanics of the patellar tendon allografts. PAA disinfection did not render the grafts either cytotoxic or liable to provoke an inflammatory response as assessed in vitro . However, the protocol was shown to increase the size of gaps between the tendon fibres in the matrix and render the grafts more susceptible to digestion with collagenase. Biomechanical studies of the tendons showed that PAA treatment had no effect on the ultimate tensile stress or Young's modulus of the tendons, and that ultimate strain was significantly higher in PAA treated tendons.

  20. Modeling the frictional interaction in the tendon-pulley system of the human finger for use in robotics.

    PubMed

    Dermitzakis, Konstantinos; Morales, Marco Roberto; Schweizer, Andreas

    2013-01-01

    Physiological studies of the human finger indicate that friction in the tendon-pulley system accounts for a considerable fraction of the total output force (9-12%) in a high-load static posteccentric configuration. Such a phenomenon can be exploited for robotic and prosthetic applications, as it can result in (1) an increase of output force or (2) a reduction of energy consumption and actuator weight. In this study, a simple frictional, two-link, one-degree-of-freedom model of a human finger was created. The model is validated against in vitro human finger data, and its behavior is examined with respect to select physiological parameters. The results point to clear benefits of incorporating friction in tendon-driven robotic fingers for actuator mass and output force. If it is indeed the case that the majority of high-load hand grasps are posteccentric, there is a clear benefit of incorporating friction in tendon-driven prosthetic hand replacements.

  1. Development of the stapedius muscle and unilateral agenesia of the tendon of the stapedius muscle in a human fetus.

    PubMed

    Rodríguez-Vázquez, J F; Mérida-Velasco, J R; Verdugo-López, S

    2010-01-01

    The objective was to analyze the development of the stapedius muscle to understand an isolated unilateral absence of the tendon of the stapedius muscle in a human fetus. The study was made on 50 human embryos and fetuses aged 38 days to 17 weeks post-conception. The stapedius muscle was formed by two anlagen, one for the tendon, which derives from the internal segment of the interhyale and another for the belly, located in the second pharyngeal arch, medially to the facial nerve and near the interhyale. In the interhyale, two segments were observed forming an angle and delimited by the attachment of the belly of the stapedius muscle. The internal segment will form the tendon. The lateral segment of the interhyale was attached to the cranial end of the Reichert's cartilage (laterohyale), and normally it disappears at the beginning of the fetal period. The right unilateral agenesia of the tendon of the stapedius muscle, observed for the first time in a human fetus of 14 weeks post-conception development (PCd), was brought about by the lack of formation or the regression of the internal segment of the interhyale. It presented a belly of the stapedius muscle with an anomalous arrangement, and with a pseudo tendon originated by the persistence of the external segment of the interhyale.

  2. Doublet potentiation in the triceps surae is limited by series compliance and dynamic fascicle behavior.

    PubMed

    Mayfield, Dean L; Lichtwark, Glen A; Cronin, Neil J; Avela, Janne; Cresswell, Andrew G

    2015-10-01

    Activation of skeletal muscle twice in quick succession results in nonlinear force summation (i.e., doublet potentiation). The force contributed by a second activation is typically of augmented amplitude, longer in duration, and generated at a greater rate. The purpose of this study was to examine force summation in a muscle attached to a compliant tendon, where considerable internal shortening occurs during a fixed-end contraction. The triceps surae of 21 (Experiment 1) and 9 (Experiment 2) young adults were maximally activated with doublet stimulation of different interstimulus intervals (ISIs) (5-100 ms) at several muscle lengths. Ultrasound images acquired from lateral gastrocnemius and soleus muscles allowed quantification of dynamic fascicle behavior. Force summation was muscle length dependent. Force augmentation was limited to a short muscle length. Lateral gastrocnemius and soleus fascicles underwent large amounts of active shortening and achieved high velocities in response to doublet stimulation, dynamics unfavorable for force production. Summation amplitude and the sensitivity of summation to ISI were dramatically depressed in the triceps surae after comparison to muscles with less fixed-end compliance. We propose that the internal shortening permitted by high series compliance limited force augmentation by offsetting and/or interfering with activation and cross-bridge processes driving augmentation. High series compliance may also reduce the sensitivity of the summated response to ISI, an assertion supported by predictions from a Hill-type muscle model. These muscles may exhibit greater force augmentation during more accustomed stretch-shorten tasks (i.e., hopping), where the compliance of the Achilles tendon actually enables near-isometric fascicle behavior.

  3. Efficiency of the flexor tendon pulley system in human cadaver hands.

    PubMed

    Rispler, D; Greenwald, D; Shumway, S; Allan, C; Mass, D

    1996-05-01

    The efficiency of the flexor tendon system was examined in a human cadaver model. Pulleys were randomly sectioned, and the results were evaluated on the basis of the tendon excursion, force generated at the fingertip, and the work (force multiplied by distance) involved, as compared to the intact pulley system. When a single minor pulley (A1 or A5) was cut, there was no statistical difference in work efficiency or excursion efficiency from controls. Cutting all minor pulleys (A1, A3, A5) lead to a significant loss in excursion efficiency. The intact three pulley systems of A2, A3, and A4 were near normal and statistically better than A2 and A4 together for work efficiency. Cutting one of the major pulleys (A2, A4) resulted in significant changes in efficiency, but what was unexpected was to find an 85% loss of both work and excursion efficiency for the loss of A4 but only an excursion difference of 94% for the loss of A2. Our findings demonstrated that in this model, with the influence of the skin removed, A4 absence produced the largest biomechanically measured efficiency changes and that a combination of A2, A3, and A4 was necessary to preserve both work and excursion efficiency.

  4. Low frequency pulsed electromagnetic field affects proliferation, tissue-specific gene expression, and cytokines release of human tendon cells.

    PubMed

    de Girolamo, L; Stanco, D; Galliera, E; Viganò, M; Colombini, A; Setti, S; Vianello, E; Corsi Romanelli, M M; Sansone, V

    2013-07-01

    Low frequency pulsed electromagnetic field (PEMF) has proven to be effective in the modulation of bone and cartilage tissue functional responsiveness, but its effect on tendon tissue and tendon cells (TCs) is still underinvestigated. PEMF treatment (1.5 mT, 75 Hz) was assessed on primary TCs, harvested from semitendinosus and gracilis tendons of eight patients, under different experimental conditions (4, 8, 12 h). Quantitative PCR analyses were conducted to identify the possible effect of PEMF on tendon-specific gene transcription (scleraxis, SCX and type I collagen, COL1A1); the release of pro- and anti-inflammatory cytokines and of vascular endothelial growth factor (VEGF) was also assessed. Our findings show that PEMF exposure is not cytotoxic and is able to stimulate TCs' proliferation. The increase of SCX and COL1A1 in PEMF-treated cells was positively correlated to the treatment length. The release of anti-inflammatory cytokines in TCs treated with PEMF for 8 and 12 h was significantly higher in comparison with untreated cells, while the production of pro-inflammatory cytokines was not affected. A dramatically higher increase of VEGF-A mRNA transcription and of its related protein was observed after PEMF exposure. Our data demonstrated that PEMF positively influence, in a dose-dependent manner, the proliferation, tendon-specific marker expression, and release of anti-inflammatory cytokines and angiogenic factor in a healthy human TCs culture model.

  5. The series-elastic shock absorber: tendons attenuate muscle power during eccentric actions.

    PubMed

    Roberts, Thomas J; Azizi, Emanuel

    2010-08-01

    Elastic tendons can act as muscle power amplifiers or energy-conserving springs during locomotion. We used an in situ muscle-tendon preparation to examine the mechanical function of tendons during lengthening contractions, when muscles absorb energy. Force, length, and power were measured in the lateral gastrocnemius muscle of wild turkeys. Sonomicrometry was used to measure muscle fascicle length independently from muscle-tendon unit (MTU) length, as measured by a muscle lever system (servomotor). A series of ramp stretches of varying velocities was applied to the MTU in fully activated muscles. Fascicle length changes were decoupled from length changes imposed on the MTU by the servomotor. Under most conditions, muscle fascicles shortened on average, while the MTU lengthened. Energy input to the MTU during the fastest lengthenings was -54.4 J/kg, while estimated work input to the muscle fascicles during this period was only -11.24 J/kg. This discrepancy indicates that energy was first absorbed by elastic elements, then released to do work on muscle fascicles after the lengthening phase of the contraction. The temporary storage of energy by elastic elements also resulted in a significant attenuation of power input to the muscle fascicles. At the fastest lengthening rates, peak instantaneous power input to the MTU reached -2,143.9 W/kg, while peak power input to the fascicles was only -557.6 W/kg. These results demonstrate that tendons may act as mechanical buffers by limiting peak muscle forces, lengthening rates, and power inputs during energy-absorbing contractions.

  6. Quantification of Internal Stress-Strain Fields in Human Tendon: Unraveling the Mechanisms that Underlie Regional Tendon Adaptations and Mal-Adaptations to Mechanical Loading and the Effectiveness of Therapeutic Eccentric Exercise

    PubMed Central

    Maganaris, Constantinos N.; Chatzistergos, Panagiotis; Reeves, Neil D.; Narici, Marco V.

    2017-01-01

    By virtue of their anatomical location between muscles and bones, tendons make it possible to transform contractile force to joint rotation and locomotion. However, tendons do not behave as rigid links, but exhibit viscoelastic tensile properties, thereby affecting the length and contractile force in the in-series muscle, but also storing and releasing elastic stain energy as some tendons are stretched and recoiled in a cyclic manner during locomotion. In the late 90s, advancements were made in the application of ultrasound scanning that allowed quantifying the tensile deformability and mechanical properties of human tendons in vivo. Since then, the main principles of the ultrasound-based method have been applied by numerous research groups throughout the world and showed that tendons increase their tensile stiffness in response to exercise training and chronic mechanical loading, in general, by increasing their size and improving their intrinsic material. It is often assumed that these changes occur homogenously, in the entire body of the tendon, but recent findings indicate that the adaptations may in fact take place in some but not all tendon regions. The present review focuses on these regional adaptability features and highlights two paradigms where they are particularly evident: (a) Chronic mechanical loading in healthy tendons, and (b) tendinopathy. In the former loading paradigm, local tendon adaptations indicate that certain regions may “see,” and therefore adapt to, increased levels of stress. In the latter paradigm, local pathological features indicate that certain tendon regions may be “stress-shielded” and degenerate over time. Eccentric exercise protocols have successfully been used in the management of tendinopathy, without much sound understanding of the mechanisms underpinning their effectiveness. For insertional tendinopathy, in particular, it is possible that the effectiveness of a loading/rehabilitation protocol depends on the topography

  7. INDUCED REMODELING OF PORCINE TENDONS TO HUMAN ANTERIOR CRUCIATE LIGAMENTS BY α-GAL EPITOPE REMOVAL AND PARTIAL CROSSLINKING.

    PubMed

    Stone, Kevin Robert; Walgenbach, Ann; Galili, Uri

    2017-01-09

    This review describes a novel method developed for processing porcine tendon and other ligament implants which enables in situ remodeling into autologous ligaments in humans. The method differs from methods using extracellular matrices (ECM) which provide post-operative ortho-biologic support (i.e. augmentation grafts) for healing of injured ligaments, in that the porcine bone-patellar-tendon-bone itself serves as the graft replacing ruptured anterior cruciate ligament (ACL). The method allows for gradual remodeling of porcine tendon into autologous human ACL while maintaining the biomechanical integrity. The method was first evaluated in a pre-clinical model of monkeys and subsequently in patients. The method overcomes detrimental effects of the natural anti-Gal antibody and harnesses anti-non gal antibodies for the remodeling process in two steps: Step 1. Elimination of α-gal epitopes- This epitope which is abundant in pigs (as in other non-primate mammals) binds the natural anti-Gal antibody which is the most abundant natural antibody in humans. This interaction, which can induce fast resorption of the porcine implant, is avoided by enzymatic elimination of α-gal epitopes from the implant with recombinant α-galactosidase. Step 2. Partial crosslinking of porcine tendon with glutaraldehyde- This crosslinking generates covalent bonds in the ECM which slow infiltration of macrophages into the implant. Anti-non gal antibodies are produced in recipients against the multiple porcine antigenic proteins and proteoglycans because of sequence differences between human and porcine homologous proteins. Anti-non gal antibodies bind to the implant ECM, recruit macrophages and induce the implant destruction by directing proteolytic activity of macrophages. Partial crosslinking of the tendon ECM decreases the extent of macrophage infiltration and degradation of the implant and enables concomitant infiltration of fibroblasts which follow the infiltrating macrophages. These

  8. Effect of acute resistance exercise and sex on human patellar tendon structural and regulatory mRNA expression.

    PubMed

    Sullivan, Bridget E; Carroll, Chad C; Jemiolo, Bozena; Trappe, Scott W; Magnusson, S Peter; Døssing, Simon; Kjaer, Michael; Trappe, Todd A

    2009-02-01

    Tendon is mainly composed of collagen and an aqueous matrix of proteoglycans that are regulated by enzymes called matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). Although it is known that resistance exercise (RE) and sex influence tendon metabolism and mechanical properties, it is uncertain what structural and regulatory components contribute to these responses. We measured the mRNA expression of tendon's main fibrillar collagens (type I and type III) and the main proteoglycans (decorin, biglycan, fibromodulin, and versican) and the regulatory enzymes MMP-2, MMP-9, MMP-3, and TIMP-1 at rest and after RE. Patellar tendon biopsy samples were taken from six individuals (3 men and 3 women) before and 4 h after a bout of RE and from a another six individuals (3 men and 3 women) before and 24 h after RE. Resting mRNA expression was used for sex comparisons (6 men and 6 women). Collagen type I, collagen type III, and MMP-2 were downregulated (P < 0.05) 4 h after RE but were unchanged (P > 0.05) 24 h after RE. All other genes remained unchanged (P > 0.05) after RE. Women had higher resting mRNA expression (P < 0.05) of collagen type III and a trend (P = 0.08) toward lower resting expression of MMP-3 than men. All other genes were not influenced (P > 0.05) by sex. Acute RE appears to stimulate a change in collagen type I, collagen type III, and MMP-2 gene regulation in the human patellar tendon. Sex influences the structural and regulatory mRNA expression of tendon.

  9. Recruitment of faster motor units is associated with greater rates of fascicle strain and rapid changes in muscle force during locomotion

    PubMed Central

    Lee, Sabrina S. M.; de Boef Miara, Maria; Arnold, Allison S.; Biewener, Andrew A.; Wakeling, James M.

    2013-01-01

    SUMMARY Animals modulate the power output needed for different locomotor tasks by changing muscle forces and fascicle strain rates. To generate the necessary forces, appropriate motor units must be recruited. Faster motor units have faster activation–deactivation rates than slower motor units, and they contract at higher strain rates; therefore, recruitment of faster motor units may be advantageous for tasks that involve rapid movements or high rates of work. This study identified motor unit recruitment patterns in the gastrocnemii muscles of goats and examined whether faster motor units are recruited when locomotor speed is increased. The study also examined whether locomotor tasks that elicit faster (or slower) motor units are associated with increased (or decreased) in vivo tendon forces, force rise and relaxation rates, fascicle strains and/or strain rates. Electromyography (EMG), sonomicrometry and muscle-tendon force data were collected from the lateral and medial gastrocnemius muscles of goats during level walking, trotting and galloping and during inclined walking and trotting. EMG signals were analyzed using wavelet and principal component analyses to quantify changes in the EMG frequency spectra across the different locomotor conditions. Fascicle strain and strain rate were calculated from the sonomicrometric data, and force rise and relaxation rates were determined from the tendon force data. The results of this study showed that faster motor units were recruited as goats increased their locomotor speeds from level walking to galloping. Slow inclined walking elicited EMG intensities similar to those of fast level galloping but different EMG frequency spectra, indicating that recruitment of the different motor unit types depended, in part, on characteristics of the task. For the locomotor tasks and muscles analyzed here, recruitment patterns were generally associated with in vivo fascicle strain rates, EMG intensity and tendon force. Together, these

  10. Muscle - tendon unit mechanical and morphological properties and sprint performance.

    PubMed

    Stafilidis, Savvas; Arampatzis, Adamantios

    2007-07-01

    The objective of this study was to determine whether sprint performance is related to the mechanical (elongation - force relationship of the tendon and aponeurosis, muscle strength) and morphological (fascicle length, pennation angle, muscle thickness) properties of the quadriceps femoris and triceps surae muscle - tendon units. Two groups of sprinters (slow, n = 11; fast, n = 17) performed maximal isometric knee extension and plantar flexion contractions on a dynamometer at 11 different muscle - tendon unit lengths. Elongation of the tendon and aponeurosis of the gastrocnemius medialis and the vastus lateralis was measured using ultrasonography. We observed no significant differences in maximal joint moments at the ankle and knee joints or morphological properties of the gastrocnemius medialis and vastus lateralis between groups (P > 0.05). The fast group exhibited greater elongation of the vastus lateralis tendon and aponeurosis at a given tendon force, and greater maximal elongation of the vastus lateralis tendon and aponeurosis during maximum voluntary contraction (P < 0.05). Furthermore, maximal elongation of the vastus lateralis tendon and aponeurosis showed a significant correlation with 100-m sprint times (r = -0.567, P = 0.003). For the elongation - force relationship at the gastrocnemius medialis tendon and aponeurosis, the two groups recorded similar values. It is suggested that the greater elongation of the vastus lateralis tendon and aponeurosis of the fast group benefits energy storage and return as well as the shortening velocity of the muscle - tendon unit.

  11. Achilles Tendonitis

    MedlinePlus

    ... You Prevent Achilles Tendonitis? Take these steps to reduce your risk of Achilles tendonitis: Stay in good shape year-round and try to keep your muscles as strong as they can be. Strong, flexible muscles work more efficiently and put less stress on your tendon. Increase the intensity and length ...

  12. Tendon crimps and peritendinous tissues responding to tensional forces.

    PubMed

    Franchi, M; Quaranta, M; De Pasquale, V; Macciocca, M; Orsini, E; Trirè, A; Ottani, V; Ruggeri, A

    2007-01-01

    Tendons transmit forces generated from muscle to bone making joint movements possible. Tendon collagen has a complex supramolecular structure forming many hierarchical levels of association; its main functional unit is the collagen fibril forming fibers and fascicles. Since tendons are enclosed by loose connective sheaths in continuity with muscle sheaths, it is likely that tendon sheaths could play a role in absorbing/transmitting the forces created by muscle contraction. In this study rat Achilles tendons were passively stretched in vivo to be observed at polarized light microscope (PLM), scanning electron microscope (SEM) and transmission electron microscope (TEM). At PLM tendon collagen fibers in relaxed rat Achilles tendons ran straight and parallel, showing a periodic crimp pattern. Similarly tendon sheaths showed apparent crimps. At higher magnification SEM and TEM revealed that in each tendon crimp large and heterogeneous collagen fibrils running straight and parallel suddenly changed their direction undergoing localized and variable modifications. These fibril modifications were named fibrillar crimps. Tendon sheaths displayed small and uniform fibrils running parallel with a wavy course without any ultrastructural aspects of crimp. Since in passively stretched Achilles tendons fibrillar crimps were still observed, it is likely that during the tendon stretching, and presumably during the tendon elongation in muscle contraction, the fibrillar crimp may be the real structural component of the tendon crimp acting as shock absorber. The peritendinous sheath can be stretched as tendon, but is not actively involved in the mechanism of shock absorber as the fibrillar crimp. The different functional behaviour of tendons and sheaths may be due to the different structural and molecular arrangement of their fibrils.

  13. Expression of extracellular matrix components and related growth factors in human tendon and muscle after acute exercise.

    PubMed

    Heinemeier, K M; Bjerrum, S S; Schjerling, P; Kjaer, M

    2013-06-01

    Acute kicking exercise induces collagen synthesis in both tendon and muscle in humans, but it is not known if this relates to increased collagen transcription and if other matrix genes are regulated. Young men performed 1 h of one-leg kicking at 67% of max workload. Biopsies were taken from the patellar tendon and vastus lateralis muscle of each leg at 2 (n = 10), 6 (n = 11), or 26 h (n = 10) after exercise. Levels of messenger ribonucleic acid mRNA for collagens, noncollagenous matrix proteins, and growth factors were measured with real-time reverse transcription polymerase chain reaction. In tendon, gene expression was unchanged except for a decrease in insulin-like growth factor-IEa (IGF-IEa; P < 0.05). In muscle, collagen expression was not significantly altered, while levels of connective tissue growth factor (CTGF), IGF-IEa, transforming growth factor-β1, -2 (TGF-β), and the TGF-β receptor II mRNA were increased (P < 0.05). Matrix components tenascin-C, fibronectin, and decorin were also induced in loaded muscle (P < 0.05), while fibromodulin was unaffected. In conclusion, the relatively robust changes in matrix components and related growth factors in muscle indicate a stimulation of extracellular matrix even with moderate exercise. However, in tendon tissue, this exercise model does not appear to induce any anabolic response on the transcriptional level.

  14. Evidence for a vertebrate catapult: elastic energy storage in the plantaris tendon during frog jumping.

    PubMed

    Astley, Henry C; Roberts, Thomas J

    2012-06-23

    Anuran jumping is one of the most powerful accelerations in vertebrate locomotion. Several species are hypothesized to use a catapult-like mechanism to store and rapidly release elastic energy, producing power outputs far beyond the capability of muscle. Most evidence for this mechanism comes from measurements of whole-body power output; the decoupling of joint motion and muscle shortening expected in a catapult-like mechanism has not been demonstrated. We used high-speed marker-based biplanar X-ray cinefluoroscopy to quantify plantaris muscle fascicle strain and ankle joint motion in frogs in order to test for two hallmarks of a catapult mechanism: (i) shortening of fascicles prior to joint movement (during tendon stretch), and (ii) rapid joint movement during the jump without rapid muscle-shortening (during tendon recoil). During all jumps, muscle fascicles shortened by an average of 7.8 per cent (54% of total strain) prior to joint movement, stretching the tendon. The subsequent period of initial joint movement and high joint angular acceleration occurred with minimal muscle fascicle length change, consistent with the recoil of the elastic tendon. These data support the plantaris longus tendon as a site of elastic energy storage during frog jumping, and demonstrate that catapult mechanisms may be employed even in sub-maximal jumps.

  15. Asymmetric deformation of contracting human gastrocnemius muscle.

    PubMed

    Kinugasa, Ryuta; Hodgson, John A; Edgerton, V Reggie; Sinha, Shantanu

    2012-02-01

    Muscle fiber deformation is related to its cellular structure, as well as its architectural arrangement within the musculoskeletal system. While playing an important role in aponeurosis displacement, and efficiency of force transmission to the tendon, such deformation also provides important clues about the underlying mechanical structure of the muscle. We hypothesized that muscle fiber cross section would deform asymmetrically to satisfy the observed constant volume of muscle during a contraction. Velocity-encoded, phase-contrast, and morphological magnetic resonance imaging techniques were used to measure changes in fascicle length, pinnation angle, and aponeurosis separation of the human gastrocnemius muscle during passive and active eccentric ankle joint movements. These parameters were then used to subsequently calculate the in-plane muscle area subtended by the two aponeuroses and fascicles and to calculate the in-plane (dividing area by fascicle length), and through-plane (dividing muscle volume by area) thicknesses. Constant-volume considerations of the whole-muscle geometry require that, as fascicle length increases, the muscle fiber cross-sectional area must decrease in proportion to the length change. Our empirical findings confirm the definition of a constant-volume rule that dictates that changes in the dimension perpendicular to the plane, i.e., through-plane thickness, (-6.0% for passive, -3.3% for eccentric) equate to the reciprocal of the changes in area (6.8% for passive, 3.7% for eccentric) for both exercise paradigms. The asymmetry in fascicle cross-section deformation for both passive and active muscle fibers is established in this study with a ∼22% in-plane and ∼6% through-plane fascicle thickness change. These fiber deformations have functional relevance, not only because they affect the force production of the muscle itself, but also because they affect the characteristics of adjacent muscles by deflecting their line of pull.

  16. Shortening behavior of the different components of muscle-tendon unit during isokinetic plantar flexions.

    PubMed

    Hauraix, Hugo; Nordez, Antoine; Dorel, Sylvain

    2013-10-01

    The torque-velocity relationship has been widely considered as reflecting the mechanical properties of the contractile apparatus, and the influence of tendinous tissues on this relationship obtained during in vivo experiments remains to be determined. This study describes the pattern of shortening of various muscle-tendon unit elements of the triceps surae at different constant angular velocities and quantifies the contributions of fascicles, tendon, and aponeurosis to the global muscle-tendon unit shortening. Ten subjects performed isokinetic plantar flexions at different preset angular velocities (i.e., 30, 90, 150, 210, 270, and 330°/s). Ultrafast ultrasound measurements were performed on the muscle belly and on the myotendinous junction of the medial and lateral gastrocnemius muscles. The contributions of fascicles, tendon, and aponeurosis to global muscle-tendon unit shortening velocity were calculated for velocity conditions for four parts of the total range of motion. For both muscles, the fascicles' contribution decreased throughout the motion (73.5 ± 21.5% for 100-90° angular range to 33.7 ± 20.2% for 80-70°), whereas the tendon contribution increased (25.8 ± 15.4 to 55.6 ± 16.8%). In conclusion, the tendon contribution to the global muscle-tendon unit shortening is significant even during a concentric contraction. However, this contribution depends on the range of motion analyzed. The intersubject variability found in the maximal fascicle shortening velocity, for a given angular velocity, suggests that some subjects might possess a more efficient musculoarticular complex to produce the movement velocity. These findings are of great interest for understanding the ability of muscle-tendon shortening velocity.

  17. Evidence against proteoglycan mediated collagen fibril load transmission and dynamic viscoelasticity in tendon.

    PubMed

    Fessel, Gion; Snedeker, Jess G

    2009-10-01

    The glycosaminoglycan (GAG) dermatan sulfate and chondroitin sulfate side-chains of small leucine-rich proteoglycans have been increasingly posited to act as molecular cross links between adjacent collagen fibrils and to directly contribute to tendon elasticity. GAGs have also been implicated in tendon viscoelasticity, supposedly affecting frictional loss during elongation or fluid flow through the extra cellular matrix. The current study sought to systematically test these theories of tendon structure-function by investigating the mechanical repercussions of enzymatic depletion of GAG complexes by chondroitinase ABC in a reproducible tendon structure-function model (rat tail tendon fascicles). The extent of GAG removal (at least 93%) was verified by relevant spectrophotometric assays and transmission electron microscopy. Dynamic viscoelastic tensile tests on GAG depleted rat tail tendon fascicle were not mechanically different from controls in storage modulus (elastic behavior) over a wide range of strain-rates (0.05, 0.5, and 5% change in length per second) in either the linear or nonlinear regions of the material curve. Loss modulus (viscoelastic behavior) was only affected in the nonlinear region at the highest strain-rate, and even this effect was marginal (19% increased loss modulus, p=0.035). Thus glycosaminoglycan chains of small leucine-rich proteoglycans do not appear to mediate dynamic elastic behavior nor do they appear to regulate the dynamic viscoelastic properties in rat tail tendon fascicles.

  18. Exogenous collagen cross-linking recovers tendon functional integrity in an experimental model of partial tear.

    PubMed

    Fessel, Gion; Wernli, Jeremy; Li, Yufei; Gerber, Christian; Snedeker, Jess G

    2012-06-01

    We investigated the hypothesis that exogenous collagen cross-linking can augment intact regions of tendon to mitigate mechanical propagation of partial tears. We first screened the low toxicity collagen cross-linkers genipin, methylglyoxal and ultra-violet (UV) light for their ability to augment tendon stiffness and failure load in rat tail tendon fascicles (RTTF). We then investigated cross-linking effects in load bearing equine superficial digital flexor tendons (SDFT). Data indicated that all three cross-linking agents augmented RTTF mechanical properties but reduced native viscoelasticity. In contrast to effects observed in fascicles, methylglyoxal treatment of SDFT detrimentally affected tendon mechanical integrity, and in the case of UV did not alter tendon mechanics. As in the RTTF experiments, genipin cross-linking of SDFT resulted in increased stiffness, higher failure loads and reduced viscoelasticity. Based on this result we assessed the efficacy of genipin in arresting tendon tear propagation in cyclic loading to failure. Genipin cross-linking secondary to a mid-substance biopsy-punch significantly reduced tissue strains, increased elastic modulus and increased resistance to fatigue failure. We conclude that genipin cross-linking of injured tendons holds potential for arresting tendon tear progression, and that implications of the treatment on matrix remodeling in living tendons should now be investigated.

  19. Continuous, bilateral Achilles' tendon vibration is not detrimental to human walk.

    PubMed

    Courtine, G; Pozzo, T; Lucas, B; Schieppati, M

    2001-05-01

    Sensory feedback from the moving limbs contributes to the regulation of animal and human locomotion. However, the question of the specific role of the various modalities is still open. Further, functional loss of leg afferent fibres due to peripheral neuropathy does not always lead to major alteration in the gait pattern. In order to gain further insight on proprioceptive control of human gait, we applied vibratory tendon stimulation, known to recruit spindle primary afferent fibres, to both triceps surae muscles during normal floor walk. This procedure would disturb organisation and execution of walking, especially if spindles fire continuously and subjects are blindfolded. Vibration induced significant, though minor, changes in duration and length of stance and swing phase, and on speed of walking and kinematics of lower limb segments. No effect was induced on angular displacement of the ankle joint or trunk and head kinematics. This paucity of effects was at variance with the perception of the subjects, who reported illusion of leg stiffness and gait imbalance. These findings would speak for a selective gating of Ia input during locomotion and emphasise the notion that the central nervous system can cope with an unusual continuous input along the Ia fibres from a key muscle like the soleus.

  20. Differential strain patterns of the human Achilles tendon determined in vivo with freehand three-dimensional ultrasound imaging.

    PubMed

    Farris, Dominic James; Trewartha, Grant; McGuigan, M Polly; Lichtwark, Glen A

    2013-02-15

    The human Achilles tendon (AT) has often been considered to act as a single elastic structure in series with the muscles of the triceps surae. As such it has been commonly modelled as a Hookean spring of uniform stiffness. However, the free AT and the proximal AT have distinctly different structures that lend themselves to different elastic properties. This study aimed to use three-dimensional freehand ultrasound imaging to determine whether the proximal AT and the free AT exhibit different elastic behaviour during sub-maximal, fixed-end contractions of the triceps surae. Six male and five female participants (mean ± s.d. age=27 ± 5 years) performed fixed position contractions of the plantar-flexors on an isokinetic dynamometer at 50% of their maximum voluntary contraction in this position. Freehand three-dimensional ultrasound imaging was used to reconstruct the free-tendon and proximal AT at rest and during contraction. The free-tendon exhibited significantly (P=0.03) greater longitudinal strain (5.2 ± 1.7%) than the proximal AT (2.6 ± 2.0%). The lesser longitudinal strain of the proximal AT was linked to the fact that it exhibited considerable transverse (orthogonal to the longitudinal direction) strains (5.0 ± 4%). The transverse strain of the proximal AT is likely due to the triceps surae muscles bulging upon contraction, and thus the level of bulging may influence the elastic behaviour of the proximal AT. This might have implications for the understanding of triceps surae muscle-tendon interaction during locomotion, tendon injury mechanics and previous measurements of AT elastic properties.

  1. Effects of resistance and stretching training programmes on the viscoelastic properties of human tendon structures in vivo

    PubMed Central

    Kubo, Keitaro; Kanehisa, Hiroaki; Fukunaga, Tetsuo

    2002-01-01

    The present study examined whether resistance and stretching training programmes altered the viscoelastic properties of human tendon structures in vivo. Eight subjects completed 8 weeks (4 days per week) of resistance training which consisted of unilateral plantar flexion at 70 % of one repetition maximum with 10 repetitions per set (5 sets per day). They performed resistance training (RT) on one side and resistance training and static stretching training (RST; 10 min per day, 7 days per week) on the other side. Before and after training, the elongation of the tendon structures in the medial gastrocnemius muscle was directly measured using ultrasonography, while the subjects performed ramp isometric plantar flexion up to the voluntary maximum, followed by a ramp relaxation. The relationship between estimated muscle force (Fm) and tendon elongation (L) was fitted to a linear regression, the slope of which was defined as stiffness. The hysteresis was calculated as the ratio of the area within the Fm-L loop to the area beneath the load portion of the curve. The stiffness increased significantly by 18.8 ± 10.4 % for RT and 15.3 ± 9.3 % for RST. There was no significant difference in the relative increase of stiffness between RT and RST. The hysteresis, on the other hand, decreased 17 ± 20 % for RST, but was unchanged for RT. These results suggested that the resistance training increased the stiffness of tendon structures as well as muscle strength and size, and the stretching training affected the viscosity of tendon structures but not the elasticity. PMID:11773330

  2. Tendon's ultrastructure.

    PubMed

    Tresoldi, Ilaria; Oliva, Francesco; Benvenuto, Monica; Fantini, Massimo; Masuelli, Laura; Bei, Roberto; Modesti, Andrea

    2013-01-01

    The structure of a tendon is an important example of complexity of ECM three-dimensional organization. The extracellular matrix (ECM) is a macromolecular network with both structural and regulatory functions. ECM components belong to four major types of macromolecules: the collagens, elastin, proteoglycans, and noncollagenous glycoproteins. Tendons are made by a fibrous, compact connective tissue that connect muscle to bone designed to transmit forces and withstand tension during muscle contraction. Here we show the ultrastructural features of tendon's components.

  3. Comparison of the inhibitory response to tendon and cutaneous afferent stimulation in the human lower limb.

    PubMed

    Rogasch, Nigel C; Burne, John A; Türker, Kemal S

    2012-01-01

    A powerful early inhibition is seen in triceps surae after transcutaneous electrical stimulation of the Achilles tendon [tendon electrical stimulation (TES)]. The aim of the present study was to confirm results from surface electromyogram (SEMG) recordings that the inhibition is not wholly or partly due to stimulation of cutaneous afferents that may lie within range of the tendon electrodes. Because of methodological limitations, SEMG does not reliably identify the time course of inhibitory and excitatory reflex components. This issue was revisited here with an analysis of changes in single motor unit (SMU) firing rate [peristimulus frequencygram (PSF)] and probability [peristimulus time histogram (PSTH)] to reexamine the time course of inhibitory SMU events that follow purely cutaneous (superficial sural) nerve stimulation. Results were then compared with similar data from TES. When compared with the reflex response to TES, sural nerve stimulation resulted in a longer onset latency of the primary inhibition and a weaker effect on SMU firing probability and rate. PSF also revealed that decreased SMU firing rates persisted during the excitation phase in SEMG, suggesting that the initial inhibition was more prolonged than previously reported. In a further study, the transcutaneous SEMG Achilles tendon response was compared with that from direct intratendon stimulation with insulated needle electrodes. This method should attenuate the SEMG response if it is wholly or partly dependent on cutaneous afferents. However, subcutaneous stimulation of the tendon produced similar components in the SEMG, confirming that cutaneous afferents made little or no contribution to the initial inhibition following TES.

  4. Achilles Tendonitis

    MedlinePlus

    ... up. Tight calf muscles or muscles that lack flexibility decrease a person's range of motion and put an extra strain on the tendon. Running or exercising on a hard or uneven surface or doing lunges or plyometrics without adequate training. A traumatic injury to the Achilles tendon. How ...

  5. Effects of estrogen on the mechanical behavior of the human Achilles tendon in vivo.

    PubMed

    Bryant, Adam L; Clark, Ross A; Bartold, Simon; Murphy, Aron; Bennell, Kim L; Hohmann, Erik; Marshall-Gradisnik, Sonya; Payne, Craig; Crossley, Kay M

    2008-10-01

    The purpose of this study was to elucidate the effect of normal fluctuating [non-monophasic oral contraceptive pill (MOCP) users] and low, consistent (MOCP users) endogenous plasma estrogen levels on the strain behavior of the Achilles tendon in vivo. Twenty women (age 28.0 +/- 4.2 yr, height 1.67 +/- 0.07 m, mass 61.6 +/- 6.8 kg) who had been using the MOCP for at least 12 mo together with 20 matched women who were non-MOCP users (age 31.9 +/- 7.3 yr, height 1.63 +/- 0.05 m, mass 62.5 +/- 5.9 kg) participated in this study. Non-MOCP users were tested at the time of lowest (menstruation) and highest (approximately same as ovulation) estrogen, whereas MOCP users, who exhibited constant and attenuated endogenous estrogen levels, were tested at day 1 and day 14 of their cycle. At each test session, maximal isometric plantarflexion efforts were performed on a calf-raise apparatus while synchronous real-time ultrasonography of the triceps surae aponeurosis was recorded. Achilles tendon strain (%) was calculated by dividing tendon displacement during plantarflexion by resting tendon length. Repeated-measures ANOVA revealed a significant (P < 0.05) main effect of subject group with significantly lower Achilles strain (25.5%) in the MOCP users compared with the non-MOCP users. In conclusion, acute fluctuations in plasma estrogen across the menstrual cycle in non-MOCP users did not alter the strain behavior of the Achilles tendon. Conversely, long-term exposure to attenuated estrogen in MOCP users resulted in a decrease in Achilles tendon strain, which is thought to be attributed to the effects of endogenous estrogen on collagen synthesis. These findings have a number of important functional and clinical implications.

  6. Altered Protein Composition and Gene Expression in Strabismic Human Extraocular Muscles and Tendons

    PubMed Central

    Agarwal, Andrea B.; Feng, Cheng-Yuan; Altick, Amy L.; Quilici, David R.; Wen, Dan; Johnson, L. Alan; von Bartheld, Christopher S.

    2016-01-01

    Purpose To determine whether structural protein composition and expression of key regulatory genes are altered in strabismic human extraocular muscles. Methods Samples from strabismic horizontal extraocular muscles were obtained during strabismus surgery and compared with normal muscles from organ donors. We used proteomics, standard and customized PCR arrays, and microarrays to identify changes in major structural proteins and changes in gene expression. We focused on muscle and connective tissue and its control by enzymes, growth factors, and cytokines. Results Strabismic muscles showed downregulation of myosins, tropomyosins, troponins, and titin. Expression of collagens and regulators of collagen synthesis and degradation, the collagenase matrix metalloproteinase (MMP)2 and its inhibitors, tissue inhibitor of metalloproteinase (TIMP)1 and TIMP2, was upregulated, along with tumor necrosis factor (TNF), TNF receptors, and connective tissue growth factor (CTGF), as well as proteoglycans. Growth factors controlling extracellular matrix (ECM) were also upregulated. Among 410 signaling genes examined by PCR arrays, molecules with downregulation in the strabismic phenotype included GDNF, NRG1, and PAX7; CTGF, CXCR4, NPY1R, TNF, NTRK1, and NTRK2 were upregulated. Signaling molecules known to control extraocular muscle plasticity were predominantly expressed in the tendon rather than the muscle component. The two horizontal muscles, medial and lateral rectus, displayed similar changes in protein and gene expression, and no obvious effect of age. Conclusions Quantification of proteins and gene expression showed significant differences in the composition of extraocular muscles of strabismic patients with respect to important motor proteins, elements of the ECM, and connective tissue. Therefore, our study supports the emerging view that the molecular composition of strabismic muscles is substantially altered. PMID:27768799

  7. Modulation of cell functions of human tendon fibroblasts by different repetitive cyclic mechanical stress patterns.

    PubMed

    Barkhausen, Tanja; van Griensven, Martijn; Zeichen, Johannes; Bosch, Ulrich

    2003-09-01

    Mechanical stress is a factor that is thought to play an essential role in tissue generation and reparation processes. The aim of the present study was to investigate the influence of different repetitive cyclic longitudinal stress patterns on proliferation, apoptosis and expression of heat shock protein (HSP) 72. To perform this study, human tendon fibroblasts were seeded on flexible silicone dishes. After adherence to the dish, cells were longitudinally stressed with three different repetitive stress patterns having a frequency of 1 Hz and an amplitude of 5%. The proliferation and apoptosis rates were investigated 0, 6, 12 and 24 hours after application of cyclic mechanical longitudinal strain. Expression of HSP 72 was tested after 0, 2, 4 and 8 hours. Control cells were also grown on silicone dishes, but did not receive any stress. Stress patterns applied during one day resulted in a significant increase in proliferation and a slight increase in apoptosis. HSP 72 expression was rather unchanged. A stress pattern applied during two days resulted in a reduced proliferation and apoptosis rate whereas the expression of HSP 72 showed a significant increase. This study shows that different stress patterns result in different cellular reactions dependent on the strength of applied stress. Repetitive stress applied during one day stimulated proliferation and apoptosis in contrast to an extended stress duration. The latter induced an inhibition of proliferation and apoptosis probably through an increased HSP 72 activity. This may be related to an excess of applied stress. Our results may implicate future modulation techniques for tissue reparation and tissue engineering.

  8. Interaponeurosis shear strain modulates behavior of myotendinous junction of the human triceps surae.

    PubMed

    Kinugasa, Ryuta; Oda, Toshiaki; Komatsu, Toshihiko; Edgerton, V Reggie; Sinha, Shantanu

    2013-11-01

    Muscle fascicles insert into a sheet-like aponeurosis. Adjacent aponeuroses are structurally in contact with each other, and ultimately merge into a common tendon. Consequently, fascicle shortening in planes of tissue layers in adjacent compartments must cause sliding between aponeuroses parallel to the acting forces. In this study, we used velocity-encoded, phase-contrast, and water-saturated spin-lattice relaxation time-weighted imaging to identify and track fascicle and aponeurosis behaviors of human medial gastrocnemius (MG) and soleus (Sol) during 15° dorsiflexion to 30° plantarflexion contractions of the ankle. Interaponeurosis shear strain, which was defined as the relative displacement of the aponeurosis at the fascicle end points (insertion) of the MG and Sol, was an average of 1.35 ± 0.27% (range 1.12 ∼ 1.87%), indicating that the strain is greater in the aponeurosis of MG fascicle insertion than the Sol. The myotendinous junction (MTJ) displacement increased significantly with decreasing interaponeurosis shear strain (P < 0.05). The magnitude of interaponeurosis shear strain had significant correlation with the temporal difference between the time at which the peak aponeurosis displacement of the MG and Sol occurred (P < 0.05). Our model also indicated that theoretical MTJ displacement varies in relation to temporal difference: no temporal difference caused the largest MTJ displacement and presence of temporal differences indicated a reduction in MTJ displacement. Therefore, we concluded that interaponeurosis shear strain is a mechanism enabling individual muscle contraction and thus specific loading of the tendon and joint.

  9. Interaponeurosis shear strain modulates behavior of myotendinous junction of the human triceps surae

    PubMed Central

    Kinugasa, Ryuta; Oda, Toshiaki; Komatsu, Toshihiko; Edgerton, V Reggie; Sinha, Shantanu

    2013-01-01

    Muscle fascicles insert into a sheet-like aponeurosis. Adjacent aponeuroses are structurally in contact with each other, and ultimately merge into a common tendon. Consequently, fascicle shortening in planes of tissue layers in adjacent compartments must cause sliding between aponeuroses parallel to the acting forces. In this study, we used velocity-encoded, phase-contrast, and water-saturated spin-lattice relaxation time-weighted imaging to identify and track fascicle and aponeurosis behaviors of human medial gastrocnemius (MG) and soleus (Sol) during 15° dorsiflexion to 30° plantarflexion contractions of the ankle. Interaponeurosis shear strain, which was defined as the relative displacement of the aponeurosis at the fascicle end points (insertion) of the MG and Sol, was an average of 1.35 ± 0.27% (range 1.12 ∼ 1.87%), indicating that the strain is greater in the aponeurosis of MG fascicle insertion than the Sol. The myotendinous junction (MTJ) displacement increased significantly with decreasing interaponeurosis shear strain (P < 0.05). The magnitude of interaponeurosis shear strain had significant correlation with the temporal difference between the time at which the peak aponeurosis displacement of the MG and Sol occurred (P < 0.05). Our model also indicated that theoretical MTJ displacement varies in relation to temporal difference: no temporal difference caused the largest MTJ displacement and presence of temporal differences indicated a reduction in MTJ displacement. Therefore, we concluded that interaponeurosis shear strain is a mechanism enabling individual muscle contraction and thus specific loading of the tendon and joint. PMID:24400149

  10. Optical properties of human tendons characterized by PSOCT and their relation to tendinopathy: a clinical study

    NASA Astrophysics Data System (ADS)

    Bagnaninchi, P. O.; Churmakov, D.; Bonesi, M.; Yang, Y.; Phelan, C.; Maffulli, N.; Meglinski, I.; El Haj, A.

    2008-02-01

    Polarisation-sensitive optical coherence tomography (PSOCT) is a non destructive technique with great potential for tendinopathy diagnosis. Functional optical assessment can be used in operating theatres to delineate in depth the margin of the non-healthy area, and limit the amount of tissue to be removed. A clinical study of 21 patients has been undertaken to correlate the optical properties of tendons to their clinical conditions. Tendons were scanned ex vivo with a fibre based time domain PSOCT. The beam from a superluminescent diode with a bandwidth of 52nm is sent through a polarizer and a polarizer modulator, and split into a sample and reference arm. After passing through polarization beam splitter, the interferences fringes are detected with two balanced detectors, for horizontal and vertical polarization. Scattering, birefringence and in depth stokes vectors are extracted from the measurements. Direct microstructural variation and changes in scattering properties are correlated with different tendinopathy and presence of scar tissue, which is cross-validated by histology. Lack of tissue organization, detected as the disappearance of the bands of birefringence, is representative of tendon degeneration. Special attention is paid to the difference between crimp patterns of different patient's tendons. As in polarization microscopy, the crimp pattern appears as extinction bands, and is particularly important as its alteration is generally symptomatic and could be used as an early diagnosis. Its optical origin is investigated by varying polarization and scanning conditions.

  11. Nonuniform strain of human soleus aponeurosis-tendon complex during submaximal voluntary contractions in vivo.

    PubMed

    Finni, Taija; Hodgson, John A; Lai, Alex M; Edgerton, V Reggie; Sinha, Shantanu

    2003-08-01

    The distribution of strain along the soleus aponeurosis tendon was examined during voluntary contractions in vivo. Eight subjects performed cyclic isometric contractions (20 and 40% of maximal voluntary contraction). Displacement and strain in the apparent Achilles tendon and in the aponeurosis were calculated from cine phase-contrast magnetic resonance images acquired with a field of view of 32 cm. The apparent Achilles tendon lengthened 2.8 and 4.7% in 20 and 40% maximal voluntary contraction, respectively. The midregion of the aponeurosis, below the gastrocnemius insertion, lengthened 1.2 and 2.2%, but the distal aponeurosis shortened 2.1 and 2.5%, respectively. There was considerable variation in the three-dimensional anatomy of the aponeurosis and muscle-tendon junction. We suggest that the nonuniformity in aponeurosis strain within an individual was due to the presence of active and passive motor units along the length of the muscle, causing variable force along the measurement site. Force transmission along intrasoleus connective tissue may also be a significant source of nonuniform strain in the aponeurosis.

  12. Tendon repair

    MedlinePlus

    ... is pain-free) Regional anesthesia (the local and surrounding areas are pain-free) General anesthesia (the patient ... used. If needed, tendons are reattached to the surrounding tissue. The surgeon examines the area to see ...

  13. Spring or string: does tendon elastic action influence wing muscle mechanics in bat flight?

    PubMed Central

    Konow, Nicolai; Cheney, Jorn A.; Roberts, Thomas J.; Waldman, J. Rhea S.; Swartz, Sharon M.

    2015-01-01

    Tendon springs influence locomotor movements in many terrestrial animals, but their roles in locomotion through fluids as well as in small-bodied mammals are less clear. We measured muscle, tendon and joint mechanics in an elbow extensor of a small fruit bat during ascending flight. At the end of downstroke, the tendon was stretched by elbow flexion as the wing was folded. At the end of upstroke, elastic energy was recovered via tendon recoil and extended the elbow, contributing to unfurling the wing for downstroke. Compared with a hypothetical ‘string-like’ system lacking series elastic compliance, the tendon spring conferred a 22.5% decrease in muscle fascicle strain magnitude. Our findings demonstrate tendon elastic action in a small flying mammal and expand our understanding of the occurrence and action of series elastic actuator mechanisms in fluid-based locomotion. PMID:26423848

  14. Effect of recombinant human platelet-derived growth factor-BB-coated sutures on Achilles tendon healing in a rat model: A histological and biomechanical study

    PubMed Central

    Cummings, Stephen H; Grande, Daniel A; Hee, Christopher K; Kestler, Hans K; Roden, Colleen M; Shah, Neil V; Razzano, Pasquale; Dines, David M; Chahine, Nadeen O

    2012-01-01

    Purpose: Repairing tendon injuries with recombinant human platelet-derived growth factor-BB has potential for improving surgical outcomes. Augmentation of sutures, a critical component of surgical tendon repair, by coating with growth factors may provide a clinically useful therapeutic device for improving tendon repair. Therefore, the purpose of this study was to (a) coat Vicryl sutures with a defined dose of recombinant human platelet-derived growth factor-BB without additional coating excipients (e.g. gelatin), (b) quantify the recombinant human platelet-derived growth factor-BB released from the suture, and (c) use the recombinant human platelet-derived growth factor-BB-coated sutures to enhance tendon repair in a rat Achilles tendon transection model. Methods: Vicryl sutures were coated with 0, 0.3, 1.0, and 10.0 mg/mL concentrations of recombinant human platelet-derived growth factor-BB using a dip-coating process. In vitro release was quantified by an enzyme-linked immunosorbent assay. Acutely transected rat Achilles tendons were repaired using one of the four suture groups (n = 12 per group). Four weeks following repair, the tensile biomechanical and histological (i.e. collagen organization and angiogenesis) properties were determined. Results: A dose-dependent bolus release of recombinant human platelet-derived growth factor-BB occurred within the first hour in vitro, followed by a gradual release over 48 h. There was a significant increase in ultimate tensile strength (p < 0.01) in the two highest recombinant human platelet-derived growth factor-BB dose groups (1.9 ± 0.5 and 2.1 ± 0.5 MPa) relative to controls (1.0 ± 0.2 MPa). The modulus significantly increased (p = 0.031) with the highest recombinant human platelet-derived growth factor-BB dose group (7.2 ± 3.8 MPa) relative to all other groups (control: 3.5 ± 0.9 MPa). No significant differences were identified for the maximum load or stiffness. The histological collagen and angiogenesis scores

  15. Age-related differences in Achilles tendon properties and triceps surae muscle architecture in vivo.

    PubMed

    Stenroth, Lauri; Peltonen, Jussi; Cronin, Neil J; Sipilä, Sarianna; Finni, Taija

    2012-11-01

    This study examined the concurrent age-related differences in muscle and tendon structure and properties. Achilles tendon morphology and mechanical properties and triceps surae muscle architecture were measured from 100 subjects [33 young (24 ± 2 yr) and 67 old (75 ± 3 yr)]. Motion analysis-assisted ultrasonography was used to determine tendon stiffness, Young's modulus, and hysteresis during isometric ramp contractions. Ultrasonography was used to measure muscle architectural features and size and tendon cross-sectional area. Older participants had 17% lower (P < 0.01) Achilles tendon stiffness and 32% lower (P < 0.001) Young's modulus than young participants. Tendon cross-sectional area was also 16% larger (P < 0.001) in older participants. Triceps surae muscle size was smaller (P < 0.05) and gastrocnemius medialis muscle fascicle length shorter (P < 0.05) in old compared with young. Maximal plantarflexion force was associated with tendon stiffness and Young's modulus (r = 0.580, P < 0.001 and r = 0.561, P < 0.001, respectively). Comparison between old and young subjects with similar strengths did not reveal a difference in tendon stiffness. The results suggest that regardless of age, Achilles tendon mechanical properties adapt to match the level of muscle performance. Old people may compensate for lower tendon material properties by increasing tendon cross-sectional area. Lower tendon stiffness in older subjects might be beneficial for movement economy in low-intensity locomotion and thus optimized for their daily activities.

  16. Frequency characteristics of human muscle and cortical responses evoked by noisy Achilles tendon vibration.

    PubMed

    Mildren, Robyn Lynne; Peters, Ryan M; Hill, Aimee J; Blouin, Jean-Sebastien; Carpenter, Mark Gregory; Inglis, J Timothy

    2017-02-16

    Noisy stimuli, along with linear systems analysis, have proven to be effective for mapping functional neural connections. We explored the use of noisy (10-115 Hz) Achilles tendon vibration to examine proprioceptive reflexes in the triceps surae muscles in standing healthy young adults (n = 8). We also examined the association between noisy vibration and electrical activity recorded over the sensorimotor cortex using electroencephalography. We applied two-minutes of vibration and recorded ongoing muscle activity of the soleus and gastrocnemii using surface electromyography (EMG). Vibration amplitude was varied to characterize reflex scaling and to examine how different stimulus levels affected postural sway. Muscle activity from the soleus and gastrocnemii were significantly correlated with the tendon vibration across a broad frequency range (~10-80 Hz), with a peak located at ~40 Hz. Vibration-EMG coherence positively scaled with stimulus amplitude in all three muscles, with soleus displaying the strongest coupling and steepest scaling. EMG responses lagged the vibration by ~38 ms, a delay that paralleled observed response latencies to tendon taps. Vibration-evoked cortical oscillations were observed at frequencies ~40-70 Hz (peak ~54 Hz) in most subjects, a finding in line with previous reports of sensory evoked γ-band oscillations. Further examination of the method revealed a) accurate reflex estimates could be obtained with <60 s of low-level (RMS=10 m/s(2)) vibration, b) responses did not habituate over two-minutes of exposure, and importantly c) noisy vibration had a minimal influence on standing balance. Our findings suggest noisy tendon vibration is an effective novel approach to characterize proprioceptive reflexes.

  17. Friction between human finger flexor tendons and pulleys at high loads.

    PubMed

    Schweizer, A; Frank, O; Ochsner, P E; Jacob, H A C

    2003-01-01

    A method was developed to indirectly measure friction between the flexor tendons and pulleys of the middle and ring finger in vivo. An isokinetic movement device to determine maximum force of wrist flexion, interphalangeal joint flexion (rolling in and out) and isolated proximal interphalangeal (PIP) joint flexion was built. Eccentric and concentric maximum force of these three different movements where gliding of the flexor tendon sheath was involved differently (least in wrist flexion) was measured and compared. Fifty-one hands in 26 male subjects were evaluated. The greatest difference between eccentric and concentric maximum force (29.9%) was found in flexion of the PIP joint. Differences in the rolling in and out movement (26.8%) and in wrist flexion (14.5%) were significantly smaller. The force of friction between flexor tendons and pulleys can be determined by the greater difference between eccentric and concentric maximum force provided by the same muscles in overcoming an external force during flexion of the interphalangeal joints and suggests the presence of a non-muscular force, such as friction. It constitutes of 9% of the eccentric flexion force in the PIP joint and therefore questions the low friction hypothesis at high loads.

  18. [Influence of Achilles tendon vibration on the human vertical posture during standing with asymmetrical leg loading].

    PubMed

    Kazennikov, O V; Kireeva, T B; Shlykov, V Iu

    2014-01-01

    The shift of center of pressure (CP) of body and CP of each leg was studied during Achilles tendon vibration of one or both legs while subject was standing with symmetrical load on the legs or with the load transferred on one leg. The CP shift of standing subject during unilateral Achilles tendon vibration depended both on the side of the tendon vibration and on the leg load. When standing with a load transferred on one leg the shift of common CP was larger than when the vibration was applied to the loaded leg. The CP shift of one leg was greater if the vibration, and the load was applied to it. Vibration of unloaded leg caused a CP shift in the contralateral loaded leg. In this case, the vibration of left unloaded leg caused no noticeable CP shift of left leg, while the vibration of the unloaded right leg caused CP shift of right foot. In the same conditions of load and vibration the CP displacement of right leg was larger than the CP shift of left foot. It can be assumed that the change in the load on the leg and unilateral vibration of leg muscles change of the internal representation of the vertical body axis, which affects the CP position of one leg during the muscles vibration.

  19. The series elastic shock absorber: tendon elasticity modulates energy dissipation by muscle during burst deceleration.

    PubMed

    Konow, Nicolai; Roberts, Thomas J

    2015-04-07

    During downhill running, manoeuvring, negotiation of obstacles and landings from a jump, mechanical energy is dissipated via active lengthening of limb muscles. Tendon compliance provides a 'shock-absorber' mechanism that rapidly absorbs mechanical energy and releases it more slowly as the recoil of the tendon does work to stretch muscle fascicles. By lowering the rate of muscular energy dissipation, tendon compliance likely reduces the risk of muscle injury that can result from rapid and forceful muscle lengthening. Here, we examine how muscle-tendon mechanics are modulated in response to changes in demand for energy dissipation. We measured lateral gastrocnemius (LG) muscle activity, force and fascicle length, as well as leg joint kinematics and ground-reaction force, as turkeys performed drop-landings from three heights (0.5-1.5 m centre-of-mass elevation). Negative work by the LG muscle-tendon unit during landing increased with drop height, mainly owing to greater muscle recruitment and force as drop height increased. Although muscle strain did not increase with landing height, ankle flexion increased owing to increased tendon strain at higher muscle forces. Measurements of the length-tension relationship of the muscle indicated that the muscle reached peak force at shorter and likely safer operating lengths as drop height increased. Our results indicate that tendon compliance is important to the modulation of energy dissipation by active muscle with changes in demand and may provide a mechanism for rapid adjustment of function during deceleration tasks of unpredictable intensity.

  20. Snapping knee caused by a popliteomeniscal fascicle tear of the lateral meniscus in a professional Taekwondo athlete.

    PubMed

    Park, Jong-Hoon; Ro, Kyung-Han; Lee, Dae-Hee

    2012-07-01

    A 19-year-old male professional Taekwondo athlete presented with a 2-year history of pain-free snapping of his right knee. He reported that his right knee joint gave way during games and training and that he could induce pain-free snapping between the proximal-to-fibular head and the lateral knee joint line. None of these physical findings suggested a meniscal pathology or ligamentous instability. Routine radiographs were normal. Magnetic resonance imaging of his right knee joint showed that the shape of the lateral meniscus was normal, and no lateral meniscus tears existed. On arthroscopic examination, popliteal hiatus view showed a posterosuperior popliteomeniscal fascicle tear between the posterior horn of the lateral meniscus and the posterior joint capsule just posteromedial to the popliteus tendon. With medial traction by probing, this popliteomeniscal tear made visible the significant subluxation of the posterior horn of the lateral meniscus to the center or anterior half of the tibial plateau. Based on the diagnosis of a posterosuperior popliteomeniscal tear of the right knee, Fast-Fix (Smith & Nephew, Andover, Massachusetts) was used for the direct repair of the peripheral portion of the lateral meniscus and joint capsule, targeting the popliteomeniscal junction. At 24 months postoperatively, the patient was performing athletic exercises relevant to his profession and was taking part in Taekwondo games, with no pain or recurrence of snapping. To the authors' knowledge, this is the first report of snapping of the lateral aspect of the knee due to a popliteomeniscal fascicle tear.

  1. Extracorporeal Shock Wave Treatment (ESWT) enhances the in vitro-induced differentiation of human tendon-derived stem/progenitor cells (hTSPCs)

    PubMed Central

    Leone, Laura; Raffa, Salvatore; Vetrano, Mario; Ranieri, Danilo; Malisan, Florence; Scrofani, Cristina; Vulpiani, Maria Chiara; Ferretti, Andrea; Torrisi, Maria Rosaria; Visco, Vincenzo

    2016-01-01

    Extracorporeal shock wave therapy (ESWT) is a non-invasive and innovative technology for the management of specific tendinopathies. In order to elucidate the ESWT-mediated clinical benefits, human Tendon-derived Stem/Progenitor cells (hTSPCs) explanted from 5 healthy semitendinosus (ST) and 5 ruptured Achilles (AT) tendons were established. While hTSPCs from the two groups showed similar proliferation rates and stem cell surface marker profiles, we found that the clonogenic potential was maintained only in cells derived from healthy donors. Interestingly, ESWT significantly accelerated hTSPCs differentiation, suggesting that the clinical benefits of ESWT may be ascribed to increased efficiency of tendon repair after injury. PMID:26843618

  2. In vivo evaluation of the elastic anisotropy of the human Achilles tendon using shear wave dispersion analysis

    NASA Astrophysics Data System (ADS)

    Brum, J.; Bernal, M.; Gennisson, J. L.; Tanter, M.

    2014-02-01

    Non-invasive evaluation of the Achilles tendon elastic properties may enhance diagnosis of tendon injury and the assessment of recovery treatments. Shear wave elastography has shown to be a powerful tool to estimate tissue mechanical properties. However, its applicability to quantitatively evaluate tendon stiffness is limited by the understanding of the physics on the shear wave propagation in such a complex medium. First, tendon tissue is transverse isotropic. Second, tendons are characterized by a marked stiffness in the 400 to 1300 kPa range (i.e. fast shear waves). Hence, the shear wavelengths are greater than the tendon thickness leading to guided wave propagation. Thus, to better understand shear wave propagation in tendons and consequently to properly estimate its mechanical properties, a dispersion analysis is required. In this study, shear wave velocity dispersion was measured in vivo in ten Achilles tendons parallel and perpendicular to the tendon fibre orientation. By modelling the tendon as a transverse isotropic viscoelastic plate immersed in fluid it was possible to fully describe the experimental data (deviation<1.4%). We show that parallel to fibres the shear wave velocity dispersion is not influenced by viscosity, while it is perpendicularly to fibres. Elasticity (found to be in the range from 473 to 1537 kPa) and viscosity (found to be in the range from 1.7 to 4 Pa.s) values were retrieved from the model in good agreement with reported results.

  3. A nonlinear constitutive model for stress relaxation in ligaments and tendons.

    PubMed

    Davis, Frances M; De Vita, Raffaella

    2012-12-01

    A novel constitutive model that describes stress relaxation in transversely isotropic soft collagenous tissues such as ligaments and tendons is presented. The model is formulated within the nonlinear integral representation framework proposed by Pipkin and Rogers (J. Mech. Phys. Solids. 16:59-72, 1968). It represents a departure from existing models in biomechanics since it describes not only the strain dependent stress relaxation behavior of collagenous tissues but also their finite strains and transverse isotropy. Axial stress-stretch data and stress relaxation data at different axial stretches are collected on rat tail tendon fascicles in order to compute the model parameters. Toward this end, the rat tail tendon fascicles are assumed to be incompressible and undergo an isochoric axisymmetric deformation. A comparison with the experimental data proves that, unlike the quasi-linear viscoelastic model (Fung, Biomechanics: Mechanics of Living Tissues. Springer, New York, 1993) the constitutive law can capture the observed nonlinearities in the stress relaxation response of rat tail tendon fascicles.

  4. The effects of dynamic stretching on plantar flexor muscle-tendon tissue properties.

    PubMed

    Samukawa, Mina; Hattori, Masaki; Sugama, Naoko; Takeda, Naoki

    2011-12-01

    Dynamic stretching is commonly used in warm-up routines for athletic activities. Even though several positive effects of dynamic stretching on athletic performance have been reported, the effects on the muscle-tendon unit (MTU) itself are still unclear. The objective of this study is to determine the effects of dynamic stretching on the ankle plantar flexor muscle-tendon properties by use of ultrasonography. Twenty healthy male subjects participated in the present study. The subjects were asked to engage in dynamic stretching of plantar flexors for 30 s and to repeat for 5 sets. Ankle dorsiflexion ROM was measured before and after the dynamic stretching. Changes in the displacement of the myotendinous junction (MTJ), pennation angle, and fascicle length were also determined by using ultrasonography. Ankle dorsiflexion ROM increased significantly after the dynamic stretching (p < 0.0001). A significant distal displacement of the MTJ was observed until the second stretching set (p < 0.001) with no significant changes thereafter. Pennation angle, and fascicle length were unaffected by the dynamic stretching. Dynamic stretching was shown to be effective in increasing ankle joint flexibility. Outcomes that could have indicated changes in muscle tissue (such as the pennation angle and fascicle length) were unaltered. However, a significant displacement of the MTJ was found, indicating some change in the tendon tissues. Therefore, dynamic stretching of the plantar flexors was considered an effective means of lengthening the tendon tissues.

  5. Repair of full-thickness tendon injury using connective tissue progenitors efficiently derived from human embryonic stem cells and fetal tissues.

    PubMed

    Cohen, Shahar; Leshansky, Lucy; Zussman, Eyal; Burman, Michael; Srouji, Samer; Livne, Erella; Abramov, Natalie; Itskovitz-Eldor, Joseph

    2010-10-01

    The use of stem cells for tissue engineering (TE) encourages scientists to design new platforms in the field of regenerative and reconstructive medicine. Human embryonic stem cells (hESC) have been proposed to be an important cell source for cell-based TE applications as well as an exciting tool for investigating the fundamentals of human development. Here, we describe the efficient derivation of connective tissue progenitors (CTPs) from hESC lines and fetal tissues. The CTPs were significantly expanded and induced to generate tendon tissues in vitro, with ultrastructural characteristics and biomechanical properties typical of mature tendons. We describe a simple method for engineering tendon grafts that can successfully repair injured Achilles tendons and restore the ankle joint extension movement in mice. We also show the CTP's ability to differentiate into bone, cartilage, and fat both in vitro and in vivo. This study offers evidence for the possibility of using stem cell-derived engineered grafts to replace missing tissues, and sets a basic platform for future cell-based TE applications in the fields of orthopedics and reconstructive surgery.

  6. Effect of fiber distribution and realignment on the nonlinear and inhomogeneous mechanical properties of human supraspinatus tendon under longitudinal tensile loading

    PubMed Central

    Lake, Spencer P.; Miller, Kristin S.; Elliott, Dawn M.; Soslowsky, Louis J.

    2010-01-01

    Tendon exhibits nonlinear stress-strain behavior that may be due, in part, to movement of collagen fibers through the extracellular matrix. While a few techniques have been developed to evaluate the fiber architecture of other soft tissues, the organizational behavior of tendon under load has not been determined. The supraspinatus tendon (SST) of the rotator cuff is of particular interest for investigation due to its complex mechanical environment and corresponding inhomogeneity. In addition, SST injury occurs frequently with limited success in treatment strategies, illustrating the need for a better understanding of SST properties. Therefore, the objective of this study was to quantitatively evaluate the inhomogeneous tensile mechanical properties, fiber organization and fiber realignment under load of human SST utilizing a novel polarized light technique. Fiber distributions were found to become more aligned under load, particularly during the low stiffness toe-region, suggesting that fiber realignment may be partly responsible for observed nonlinear behavior. Fiber alignment was found to correlate significantly with mechanical parameters, providing evidence for strong structure-function relationships in tendon. Human SST exhibits complex, inhomogeneous mechanical properties and fiber distributions, perhaps due to its complex loading environment. Surprisingly, histological grade of degeneration did not correlate with mechanical properties. PMID:19544524

  7. Effect of Hypoxia on Self-Renewal Capacity and Differentiation in Human Tendon-Derived Stem Cells

    PubMed Central

    Yu, Yang; Lin, Lixiang; Zhou, Yifei; Lu, Xiaolang; Shao, Xiwen; Lin, Chuanlu; Yu, Kehe; Zhang, Xiaolei; Hong, Jianjun; Chen, Ying

    2017-01-01

    Background Hypoxic conditions play roles in functioning of human tendon-derived stem cells (hTSCs). The goal of this study was to investigate the effect of various hypoxic conditions in self-renewal capacity and differentiation of TSCs. Material/Methods hTSCs was obtain from supraspinatus tendon donors. Colony formation and cell proliferation assay were used to assess the self-renewal of hTSCs. qRT-PCT and Western blot analysis were used to examine stemness and multi-differentiation potential of hTSCs. Results We found that culturing at 5% O2 is more beneficial for the self-renewal of hTSCs than the other 3 culture conditions, with larger colony size and numbers. The proliferation of hTSCs in 5%, 10%, and 20% O2 cultures increased after seeding. The number of cells in the 5% O2 condition was higher than that in other culture; however, self-renewal capacity of hTSCs in 0.5% O2 was inhibited. The expression levels of stem cell markers, including NS, Nanog, Oct-4, and SSEA-4, were highest in 0.5% O2 culture. Furthermore, hTSCs cultured in 20% O2 exhibited significantly higher expression of the 3 markers (PPAR-γ, Sox-9, and Runx-2). Conclusions Hypoxic condition of culture encouraged self-renewal capacity of hTSCs, but inhibited their multi-differentiation potential, compared to normoxic condition of culture. Moreover, excessively low oxygen concentration impaired the capacity of hTSCs. PMID:28302994

  8. Achilles tendon repair

    MedlinePlus

    Achilles tendon rupture-surgery; Percutaneous Achilles tendon rupture repair ... To fix your torn Achilles tendon, the surgeon will: Make a cut down the back of your heel Make several small cuts rather than one large cut ...

  9. Evolution of the Achilles tendon: The athlete's Achilles heel?

    PubMed

    Malvankar, S; Khan, W S

    2011-12-01

    The Achilles tendon is believed to have first developed two million years ago enabling humans to run twice as fast. However if the Achilles tendon is so important in terms of evolution, then why is this tendon so prone to injury - especially for those more active like athletes. The Achilles tendon had an integral role in evolving apes from a herbivorous diet to early humans who started hunting for food over longer distances, resulting in bipedal locomotion. Evolutionary advantages of the Achilles tendon includes it being the strongest tendon in the body, having an energy-saving mechanism for fast locomotion, allows humans to jump and run, and additionally is a spring and shock absorber during gait. Considering these benefits it is therefore not surprising that studies have shown athletes have thicker Achilles tendons than subjects who are less active. However, contradictory to these findings that show the importance of the Achilles tendon for athletes, it is well known that obtaining an Achilles tendon injury for an athlete can be career-altering. A disadvantage of the Achilles tendon is that the aetiology of its pathology is complicated. Achilles tendon ruptures are believed to be caused by overloading the tensed tendon, like during sports. However studies have also shown athlete Achilles tendon ruptures to have degenerative changes in the tendon. Other flaws of the Achilles tendon are its non-uniform vascularity and incomplete repair system which may suggest the Achilles tendon is on the edge of evolution. Research has shown that there is a genetic influence on the predisposition a person has towards Achilles tendon injuries. So if this tendon is here to stay in our anatomy, and it probably is due to the slow rate of evolution in humans, research in genetic modification could be used to decrease athletes' predisposition to Achilles tendinopathy.

  10. Development of the Human Biceps Brachii Tendon and Coracoglenoid Ligament (7th-12th Week of Development).

    PubMed

    de la Cuadra-Blanco, Crótida; Arráez-Aybar, Luis A; Murillo-González, Jorge A; Herrera-Lara, Manuel E; Mérida-Velasco, Juan A; Mérida-Velasco, José R

    2017-02-10

    The goal of this study is to clarify the development of the long head of the biceps brachii tendon (LHBT) and to verify the existence and development of the coracoglenoid ligament. Histological preparations of 22 human embryos (7-8 weeks of development) and 43 human fetuses (9-12 weeks of development) were studied bilaterally using a conventional optical microscope. The articular interzone gives rise to the LHBT, glenoid labrum, and articular capsule. During the fetal period, it was observed that in 50 cases (58%), the LHBT originated from both the glenoid labrum and the scapula, while in 36 cases (42%), it originated only from the glenoid labrum. The coracoglenoid ligament, first described by Sappey in 1867, is a constant structure that originates at the base of the coracoid process and projects toward the glenoid labrum zone, which is related to the origin of the LHBT. The coracoglenoid ligament was more easily identifiable in the 36 cases in which the LHBT originated only from the glenoid labrum. We suggest that the coracoglenoid ligament is a constant anatomical structure, is not derived from the articular interzone unlike the LHBT, and contributes to the fixation of the glenoid labrum in the scapula in cases in which the LHBT originated only from the glenoid labrum. We postulate that, when the LHBT is fixed only at the glenoid labrum, alterations in the coracoglenoid ligament could lead to a less sufficient attachment of the glenoid labrum to the scapula which could predispose to a superior labral lesion.

  11. Imaging and simulation of Achilles tendon dynamics: Implications for walking performance in the elderly.

    PubMed

    Franz, Jason R; Thelen, Darryl G

    2016-06-14

    The Achilles tendon (AT) is a complex structure, consisting of distinct fascicle bundles arising from each triceps surae muscle that may act as mechanically independent structures. Advances in tissue imaging are rapidly accelerating our understanding of the complexities of functional Achilles tendon behavior, with potentially important implications for musculoskeletal injury and performance. In this overview of our recent contributions to these efforts, we present the results of complementary experimental and computational approaches to investigate AT behavior during walking and its potential relevance to reduced triceps surae mechanical performance due to aging. Our experimental evidence reveals that older tendons exhibit smaller differences in tissue deformations than young adults between regions of the AT presumed to arise from the gastrocnemius and soleus muscles. These observations are consistent with a reduced capacity for inter-fascicle sliding within the AT, which could have implications for the mechanical independence of the triceps surae muscles. More uniform AT deformations are also correlated with hallmark biomechanical features of elderly gait - namely, a loss of net ankle moment, power, and positive work during push-off. Simulating age-related reductions in the capacity for inter-fascicle sliding in the AT during walking predicts detriments in gastrocnemius muscle-tendon mechanical performance coupled with underlying shifts in fascicle kinematics during push-off. AT compliance, also suspected to vary due to age, systematically modulates those effects. By integrating in vivo imaging with computational modeling, we have gained theoretical insight into multi-scale biomechanical changes due to aging, hypotheses regarding their functional effects, and opportunities for experiments that validate or invalidate these assertions.

  12. Hyaluronic acid and tendon lesions

    PubMed Central

    Kaux, Jean-François; Samson, Antoine; Crielaard, Jean-Michel

    2015-01-01

    Summary Introduction recently, the viscoelastic properties of hyaluronic acid (HA) on liquid connective tissue have been proposed for the treatment of tendinopathies. Some fundamental studies show encouraging results on hyaluronic acid’s ability to promote tendon gliding and reduce adhesion as well as to improve tendon architectural organisation. Some observations also support its use in a clinical setting to improve pain and function. This literature review analyses studies relating to the use of hyaluronic acid in the treatment of tendinopathies. Methods this review was constructed using the Medline database via Pubmed, Scopus and Google Scholar. The key words hyaluronic acid, tendon and tendinopathy were used for the research. Results in total, 28 articles (in English and French) on the application of hyaluronic acid to tendons were selected for their relevance and scientific quality, including 13 for the in vitro part, 7 for the in vivo animal part and 8 for the human section. Conclusions preclinical studies demonstrate encouraging results: HA permits tendon gliding, reduces adhesions, creates better tendon architectural organisation and limits inflammation. These laboratory observations appear to be supported by limited but encouraging short-term clinical results on pain and function. However, controlled randomised studies are still needed. PMID:26958533

  13. Management of Extensor Tendon Injuries

    PubMed Central

    Griffin, M; Hindocha, S; Jordan, D; Saleh, M; Khan, W

    2012-01-01

    Extensor tendon injuries are very common injuries, which inappropriately treated can cause severe lasting impairment for the patient. Assessment and management of flexor tendon injuries has been widely reviewed, unlike extensor injuries. It is clear from the literature that extensor tendon repair should be undertaken immediately but the exact approach depends on the extensor zone. Zone I injuries otherwise known as mallet injuries are often closed and treated with immobilisaton and conservative management where possible. Zone II injuries are again conservatively managed with splinting. Closed Zone III or ‘boutonniere’ injuries are managed conservatively unless there is evidence of displaced avulsion fractures at the base of the middle phalanx, axial and lateral instability of the PIPJ associated with loss of active or passive extension of the joint or failed non-operative treatment. Open zone III injuries are often treated surgically unless splinting enable the tendons to come together. Zone V injuries, are human bites until proven otherwise requires primary tendon repair after irrigation. Zone VI injuries are close to the thin paratendon and thin subcutaneous tissue which strong core type sutures and then splinting should be placed in extension for 4-6 weeks. Complete lacerations to zone IV and VII involve surgical primary repair followed by 6 weeks of splinting in extension. Zone VIII require multiple figure of eight sutures to repair the muscle bellies and static immobilisation of the wrist in 45 degrees of extension. To date there is little literature documenting the quality of repairing extensor tendon injuries however loss of flexion due to extensor tendon shortening, loss of flexion and extension resulting from adhesions and weakened grip can occur after surgery. This review aims to provide a systematic examination method for assessing extensor injuries, presentation and management of all type of extensor tendon injuries as well as guidance on

  14. Functional assessment of gap junctions in monolayer and three-dimensional cultures of human tendon cells using fluorescence recovery after photobleaching

    NASA Astrophysics Data System (ADS)

    Kuzma-Kuzniarska, Maria; Yapp, Clarence; Pearson-Jones, Thomas W.; Jones, Andrew K.; Hulley, Philippa A.

    2014-01-01

    Gap junction-mediated intercellular communication influences a variety of cellular activities. In tendons, gap junctions modulate collagen production, are involved in strain-induced cell death, and are involved in the response to mechanical stimulation. The aim of the present study was to investigate gap junction-mediated intercellular communication in healthy human tendon-derived cells using fluorescence recovery after photobleaching (FRAP). The FRAP is a noninvasive technique that allows quantitative measurement of gap junction function in living cells. It is based on diffusion-dependent redistribution of a gap junction-permeable fluorescent dye. Using FRAP, we showed that human tenocytes form functional gap junctions in monolayer and three-dimensional (3-D) collagen I culture. Fluorescently labeled tenocytes following photobleaching rapidly reacquired the fluorescent dye from neighboring cells, while HeLa cells, which do not communicate by gap junctions, remained bleached. Furthermore, both 18 β-glycyrrhetinic acid and carbenoxolone, standard inhibitors of gap junction activity, impaired fluorescence recovery in tendon cells. In both monolayer and 3-D cultures, intercellular communication in isolated cells was significantly decreased when compared with cells forming many cell-to-cell contacts. In this study, we used FRAP as a tool to quantify and experimentally manipulate the function of gap junctions in human tenocytes in both two-dimensional (2-D) and 3-D cultures.

  15. Bilateral Patellar Tendon Rupture

    DTIC Science & Technology

    2009-07-01

    within the tendon or systemic disorders such as lupus erythematosus , diabetes mellitus, chronic kidney disease, rheumatologic disease, and local or...factors for patellar tendon rupture include obesity, male gender, age 30-40, activities that increase patellar stress, systemic lupus erythematosus ...patellar tendon rupture is a rare occurrence usually associated with chronic degeneration of tendon fibers, use of steroids, or systemic illness. Our

  16. Long-term use of high-heeled shoes alters the neuromechanics of human walking.

    PubMed

    Cronin, Neil J; Barrett, Rod S; Carty, Christopher P

    2012-03-01

    Human movement requires an ongoing, finely tuned interaction between muscular and tendinous tissues, so changes in the properties of either tissue could have important functional consequences. One condition that alters the functional demands placed on lower limb muscle-tendon units is the use of high-heeled shoes (HH), which force the foot into a plantarflexed position. Long-term HH use has been found to shorten medial gastrocnemius muscle fascicles and increase Achilles tendon stiffness, but the consequences of these changes for locomotor muscle-tendon function are unknown. This study examined the effects of habitual HH use on the neuromechanical behavior of triceps surae muscles during walking. The study population consisted of 9 habitual high heel wearers who had worn shoes with a minimum heel height of 5 cm at least 40 h/wk for a minimum of 2 yr, and 10 control participants who habitually wore heels for less than 10 h/wk. Participants walked at a self-selected speed over level ground while ground reaction forces, ankle and knee joint kinematics, lower limb muscle activity, and gastrocnemius fascicle length data were acquired. In long-term HH wearers, walking in HH resulted in substantial increases in muscle fascicle strains and muscle activation during the stance phase compared with barefoot walking. The results suggest that long-term high heel use may compromise muscle efficiency in walking and are consistent with reports that HH wearers often experience discomfort and muscle fatigue. Long-term HH use may also increase the risk of strain injuries.

  17. Plyometric Training Favors Optimizing Muscle-Tendon Behavior during Depth Jumping.

    PubMed

    Hirayama, Kuniaki; Iwanuma, Soichiro; Ikeda, Naoki; Yoshikawa, Ayumi; Ema, Ryoichi; Kawakami, Yasuo

    2017-01-01

    The purpose of the present study was to elucidate how plyometric training improves stretch-shortening cycle (SSC) exercise performance in terms of muscle strength, tendon stiffness, and muscle-tendon behavior during SSC exercise. Eleven men were assigned to a training group and ten to a control group. Subjects in the training group performed depth jumps (DJ) using only the ankle joint for 12 weeks. Before and after the period, we observed reaction forces at foot, muscle-tendon behavior of the gastrocnemius, and electromyographic activities of the triceps surae and tibialis anterior during DJ. Maximal static plantar flexion strength and Achilles tendon stiffness were also determined. In the training group, maximal strength remained unchanged while tendon stiffness increased. The force impulse of DJ increased, with a shorter contact time and larger reaction force over the latter half of braking and initial half of propulsion phases. In the latter half of braking phase, the average electromyographic activity (mEMG) increased in the triceps surae and decreased in tibialis anterior, while fascicle behavior of the gastrocnemius remained unchanged. In the initial half of propulsion, mEMG of triceps surae and shortening velocity of gastrocnemius fascicle decreased, while shortening velocity of the tendon increased. These results suggest that the following mechanisms play an important role in improving SSC exercise performance through plyometric training: (1) optimization of muscle-tendon behavior of the agonists, associated with alteration in the neuromuscular activity during SSC exercise and increase in tendon stiffness and (2) decrease in the neuromuscular activity of antagonists during a counter movement.

  18. Plyometric Training Favors Optimizing Muscle–Tendon Behavior during Depth Jumping

    PubMed Central

    Hirayama, Kuniaki; Iwanuma, Soichiro; Ikeda, Naoki; Yoshikawa, Ayumi; Ema, Ryoichi; Kawakami, Yasuo

    2017-01-01

    The purpose of the present study was to elucidate how plyometric training improves stretch–shortening cycle (SSC) exercise performance in terms of muscle strength, tendon stiffness, and muscle–tendon behavior during SSC exercise. Eleven men were assigned to a training group and ten to a control group. Subjects in the training group performed depth jumps (DJ) using only the ankle joint for 12 weeks. Before and after the period, we observed reaction forces at foot, muscle–tendon behavior of the gastrocnemius, and electromyographic activities of the triceps surae and tibialis anterior during DJ. Maximal static plantar flexion strength and Achilles tendon stiffness were also determined. In the training group, maximal strength remained unchanged while tendon stiffness increased. The force impulse of DJ increased, with a shorter contact time and larger reaction force over the latter half of braking and initial half of propulsion phases. In the latter half of braking phase, the average electromyographic activity (mEMG) increased in the triceps surae and decreased in tibialis anterior, while fascicle behavior of the gastrocnemius remained unchanged. In the initial half of propulsion, mEMG of triceps surae and shortening velocity of gastrocnemius fascicle decreased, while shortening velocity of the tendon increased. These results suggest that the following mechanisms play an important role in improving SSC exercise performance through plyometric training: (1) optimization of muscle–tendon behavior of the agonists, associated with alteration in the neuromuscular activity during SSC exercise and increase in tendon stiffness and (2) decrease in the neuromuscular activity of antagonists during a counter movement. PMID:28179885

  19. Structure-mechanics relationships in mineralized tendons.

    PubMed

    Spiesz, Ewa M; Zysset, Philippe K

    2015-12-01

    In this paper, we review the hierarchical structure and the resulting elastic properties of mineralized tendons as obtained by various multiscale experimental and computational methods spanning from nano- to macroscale. The mechanical properties of mineralized collagen fibres are important to understand the mechanics of hard tissues constituted by complex arrangements of these fibres, like in human lamellar bone. The uniaxial mineralized collagen fibre array naturally occurring in avian tendons is a well studied model tissue for investigating various stages of tissue mineralization and the corresponding elastic properties. Some avian tendons mineralize with maturation, which results in a graded structure containing two zones of distinct morphology, circumferential and interstitial. These zones exhibit different amounts of mineral, collagen, pores and a different mineral distribution between collagen fibrillar and extrafibrillar space that lead to distinct elastic properties. Mineralized tendon cells have two phenotypes: elongated tenocytes placed between fibres in the circumferential zone and cuboidal cells with lower aspect ratios in the interstitial zone. Interestingly some regions of avian tendons seem to be predestined to mineralization, which is exhibited as specific collagen cross-linking patterns as well as distribution of minor tendon constituents (like proteoglycans) and loss of collagen crimp. Results of investigations in naturally mineralizing avian tendons may be useful in understanding the pathological mineralization occurring in some human tendons.

  20. Multidimensional models for predicting muscle structure and fascicle pennation.

    PubMed

    Randhawa, Avleen; Wakeling, James M

    2015-10-07

    Pennation angles change during muscle contraction and must be tracked by muscle models. When muscles contract they can change in depth (distance between the bounding sheets of aponeurosis) or width, and this is related to pennation angle and muscle fascicle length. As a simplification to these relationships, many models of pennate muscle assume a constant distance between aponeuroses during contraction (constant depth). It is possible that these 1D models do not recreate the internal structure of muscles adequately, whereas 2D panel models that assume a constant panel area, or 3D models that assume a constant muscle volume may better predict the structural changes that occur within muscle during contraction. However, these ideas have never been validated in man. The purpose of this study was to test the accuracy with which 1D, 2D or 3D structural models of muscle could predict the pennation and muscle depth within the medial gastrocnemius (MG) and lateral gastrocnemius (LG) in man during ankle plantarflexions. The 1D model, by definition, was unable to account for changes in muscle depth. The 2D model predicted change in depth as the aponeurosis was loaded, but could only allow a decrease in depth as the aponeurosis is stretched. This was not sufficient to predict the increases in depth that occur in the LG during plantarflexion. The 3D model had the ability to predict either increases or decreases in depth during the ankle plantarflexions and predicted opposing changes in depth that occurred between the MG and LG, whilst simultaneously predicting the pennation more accurately than the 1D or 2D models. However, when using mean parameters, the 3D model performed no better than the more simple 1D model, and so if the intent of a model is purely to establish a good relation between fascicle length and pennation then the 1D model is a suitable choice for these muscles.

  1. Diseases of the tendons and tendon sheaths.

    PubMed

    Steiner, Adrian; Anderson, David E; Desrochers, André

    2014-03-01

    Contracted flexor tendon leading to flexural deformity is a common congenital defect in cattle. Arthrogryposis is a congenital syndrome of persistent joint contracture that occurs frequently in Europe as a consequence of Schmallenberg virus infection of the dam. Spastic paresis has a hereditary component, and affected cattle should not be used for breeding purposes. The most common tendon avulsion involves the deep digital flexor tendon. Tendon disruptions may be successfully managed by tenorrhaphy and external coaptation or by external coaptation alone. Medical management alone is unlikely to be effective for purulent tenosynovitis.

  2. Transverse Compression of Tendons.

    PubMed

    Salisbury, S T Samuel; Buckley, C Paul; Zavatsky, Amy B

    2016-04-01

    A study was made of the deformation of tendons when compressed transverse to the fiber-aligned axis. Bovine digital extensor tendons were compression tested between flat rigid plates. The methods included: in situ image-based measurement of tendon cross-sectional shapes, after preconditioning but immediately prior to testing; multiple constant-load creep/recovery tests applied to each tendon at increasing loads; and measurements of the resulting tendon displacements in both transverse directions. In these tests, friction resisted axial stretch of the tendon during compression, giving approximately plane-strain conditions. This, together with the assumption of a form of anisotropic hyperelastic constitutive model proposed previously for tendon, justified modeling the isochronal response of tendon as that of an isotropic, slightly compressible, neo-Hookean solid. Inverse analysis, using finite-element (FE) simulations of the experiments and 10 s isochronal creep displacement data, gave values for Young's modulus and Poisson's ratio of this solid of 0.31 MPa and 0.49, respectively, for an idealized tendon shape and averaged data for all the tendons and E = 0.14 and 0.10 MPa for two specific tendons using their actual measured geometry. The compression load versus displacement curves, as measured and as simulated, showed varying degrees of stiffening with increasing load. This can be attributed mostly to geometrical changes in tendon cross section under load, varying according to the initial 3D shape of the tendon.

  3. Medial gastrocnemius muscle growth during adolescence is mediated by increased fascicle diameter rather than by longitudinal fascicle growth.

    PubMed

    Weide, Guido; Huijing, Peter A; Maas, Josina C; Becher, Jules G; Harlaar, Jaap; Jaspers, Richard T

    2015-06-01

    Using a cross-sectional design, the purpose of this study was to determine how pennate gastrocnemius medialis (GM) muscle geometry changes as a function of adolescent age. Sixteen healthy adolescent males (aged 10-19 years) participated in this study. GM muscle geometry was measured within the mid-longitudinal plane obtained from a 3D voxel-array composed of transverse ultrasound images. Images were taken at footplate angles corresponding to standardised externally applied footplate moments (between 4 Nm plantar flexion and 6 Nm dorsal flexion). Muscle activity was recorded using surface electromyography (EMG), expressed as a percentage of maximal voluntary contraction (%MVC). To minimise the effects of muscle excitation, EMG inclusion criteria were set at <10% of MVC. In practice, however, normalised EMG levels were much lower. For adolescent subjects with increasing ages, GM muscle (belly) length increased due to an increase in the length component of the physiological cross-sectional area measured within the mid-longitudinal plane. No difference was found between fascicles at different ages, but the aponeurosis length and pennation angle increased by 0.5 cm year(-1) and 0.5° per year, respectively. Footplate angles corresponding to externally applied 0 and 4 Nm plantarflexion moments were not associated with different adolescent ages. In contrast, footplate angles corresponding to externally applied 4 and 6 Nm dorsal flexion moments decreased by 10° between 10 and 19 years. In conclusion, we found that in adolescents' pennate GM muscles, longitudinal muscle growth is mediated predominantly by increased muscle fascicle diameter.

  4. Triceps surae muscle-tendon properties in older endurance- and sprint-trained athletes.

    PubMed

    Stenroth, Lauri; Cronin, Neil J; Peltonen, Jussi; Korhonen, Marko T; Sipilä, Sarianna; Finni, Taija

    2016-01-01

    Previous studies have shown that aging is associated with alterations in muscle architecture and tendon properties (Morse CI, Thom JM, Birch KM, Narici MV. Acta Physiol Scand 183: 291-298, 2005; Narici MV, Maganaris CN, Reeves ND, Capodaglio P. J Appl Physiol 95: 2229-2234, 2003; Stenroth L, Peltonen J, Cronin NJ, Sipila S, Finni T. J Appl Physiol 113: 1537-1544, 2012). However, the possible influence of different types of regular exercise loading on muscle architecture and tendon properties in older adults is poorly understood. To address this, triceps surae muscle-tendon properties were examined in older male endurance (OE, n = 10, age = 74.0 ± 2.8 yr) and sprint runners (OS, n = 10, age = 74.4 ± 2.8 yr), with an average of 42 yr of regular training experience, and compared with age-matched [older control (OC), n = 33, age = 74.8 ± 3.6 yr] and young untrained controls (YC, n = 18, age = 23.7 ± 2.0 yr). Compared with YC, Achilles tendon cross-sectional area (CSA) was 22% (P = 0.022), 45% (P = 0.001), and 71% (P < 0.001) larger in OC, OE, and OS, respectively. Among older groups, OS had significantly larger tendon CSA compared with OC (P = 0.033). No significant between-group differences were observed in Achilles tendon stiffness. In older groups, Young's modulus was 31-44%, and maximal tendon stress 44-55% lower, than in YC (P ≤ 0.001). OE showed shorter soleus fascicle length than both OC (P < 0.05) and YC (P < 0.05). These data suggest that long-term running does not counteract the previously reported age-related increase in tendon CSA, but, instead, may have an additive effect. The greatest Achilles tendon CSA was observed in OS followed by OE and OC, suggesting that adaptation to running exercise is loading intensity dependent. Achilles tendon stiffness was maintained in older groups, even though all older groups displayed larger tendon CSA and lower tendon Young's modulus. Shorter soleus muscle fascicles in OE runners may be an adaptation to life

  5. In vivo quantification of the shear modulus of the human Achilles tendon during passive loading using shear wave dispersion analysis

    NASA Astrophysics Data System (ADS)

    Helfenstein-Didier, C.; Andrade, R. J.; Brum, J.; Hug, F.; Tanter, M.; Nordez, A.; Gennisson, J.-L.

    2016-03-01

    The shear wave velocity dispersion was analyzed in the Achilles tendon (AT) during passive dorsiflexion using a phase velocity method in order to obtain the tendon shear modulus (C 55). Based on this analysis, the aims of the present study were (i) to assess the reproducibility of the shear modulus for different ankle angles, (ii) to assess the effect of the probe locations, and (iii) to compare results with elasticity values obtained with the supersonic shear imaging (SSI) technique. The AT shear modulus (C 55) consistently increased with the ankle dorsiflexion (N  =  10, p  <  0.05). Furthermore, the technique showed a very good reproducibility (all standard error of the mean values  <10.7 kPa and all coefficient of variation (CV) values  ⩽0.05%). In addition, independently from the ankle dorsiflexion, the shear modulus was significantly higher in the proximal location compared to the more distal one. The shear modulus provided by SSI was always lower than C55 and the difference increased with the ankle dorsiflexion. However, shear modulus values provided by both methods were highly correlated (R  =  0.84), indicating that the conventional shear wave elastography technique (SSI technique) can be used to compare tendon mechanical properties across populations. Future studies should determine the clinical relevance of the shear wave dispersion analysis, for instance in the case of tendinopathy or tendon tear.

  6. Polarization-dependent optical second-harmonic imaging of a rat-tail tendon.

    PubMed

    Stoller, Patrick; Kim, Beop-Min; Rubenchik, Alexander M; Reiser, Karen M; Da Silva, Luiz B

    2002-04-01

    Using scanning confocal microscopy, we measure the backscattered second harmonic signal generated by a 100 fs laser in rat-tail tendon collagen. Damage to the sample is avoided by using a continuous scanning technique, rather than measuring the signal at discrete points. The second harmonic signal varies by about a factor of 2 across a single cross section of the rat-tail tendon fascicle. The signal intensity depends both on the collagen organization and the backscattering efficiency. This implies that we cannot use intensity measurements alone to characterize collagen structure. However, we can infer structural information from the polarization dependence of the second harmonic signal. Axial and transverse scans for different linear polarization angles of the input beam show that second harmonic generation (SHG) in the rat-tail tendon depends strongly on the polarization of the input laser beam. We develop an analytical model for the SHG as a function of the polarization angle in the rat-tail tendon. We apply this model in determining the orientation of collagen fibrils in the fascicle and the ratio gamma between the two independent elements of the second-order nonlinear susceptibility tensor. There is a good fit between our model and the measured data.

  7. Measuring Regional Changes in Damaged Tendon

    NASA Astrophysics Data System (ADS)

    Frisch, Catherine Kayt Vincent

    Mechanical properties of tendon predict tendon health and function, but measuring these properties in vivo is difficult. An ultrasound-based (US) analysis technique called acoustoelastography (AE) uses load-dependent changes in the reflected US signal to estimate tissue stiffness non-invasively. This thesis explores whether AE can provide information about stiffness alteration resulting from tendon tears both ex vivo and in vivo. An ex vivo ovine infraspinatus tendon model suggests that the relative load transmitted by the different tendon layers transmit different fractions of the load and that ultrasound echo intensity change during cyclic loading decreases, becoming less consistent once the tendon is torn. An in vivo human tibialis anterior tendon model using electrically stimulated twitch contractions investigated the feasibility of measuring the effect in vivo. Four of the five subjects showed the expected change and that the muscle contraction times calculated using the average grayscale echo intensity change compared favorably with the times calculated based on the force data. Finally an AE pilot study with patients who had rotator cuff tendon tears found that controlling the applied load and the US view of the system will be crucial to a successful in vivo study.

  8. Biologics for tendon repair☆

    PubMed Central

    Docheva, Denitsa; Müller, Sebastian A.; Majewski, Martin; Evans, Christopher H.

    2015-01-01

    Tendon injuries are common and present a clinical challenge to orthopedic surgery mainly because these injuries often respond poorly to treatment and require prolonged rehabilitation. Therapeutic options used to repair ruptured tendons have consisted of suture, autografts, allografts, and synthetic prostheses. To date, none of these alternatives has provided a successful long-term solution, and often the restored tendons do not recover their complete strength and functionality. Unfortunately, our understanding of tendon biology lags far behind that of other musculoskeletal tissues, thus impeding the development of new treatment options for tendon conditions. Hence, in this review, after introducing the clinical significance of tendon diseases and the present understanding of tendon biology, we describe and critically assess the current strategies for enhancing tendon repair by biological means. These consist mainly of applying growth factors, stem cells, natural biomaterials and genes, alone or in combination, to the site of tendon damage. A deeper understanding of how tendon tissue and cells operate, combined with practical applications of modern molecular and cellular tools could provide the long awaited breakthrough in designing effective tendon-specific therapeutics and overall improvement of tendon disease management. PMID:25446135

  9. Musculoskeletal diseases—tendon

    PubMed Central

    Sakabe, Tomoya; Sakai, Takao

    2011-01-01

    Introduction Tendons establish specific connections between muscles and the skeleton by transferring contraction forces from skeletal muscle to bone thereby allowing body movement. Tendon physiology and pathology are heavily dependent on mechanical stimuli. Tendon injuries clinically represent a serious and still unresolved problem since damaged tendon tissues heal very slowly and no surgical treatment can restore a damaged tendon to its normal structural integrity and mechanical strength. Understanding how mechanical stimuli regulate tendon tissue homeostasis and regeneration will improve the treatment of adult tendon injuries that still pose a great challenge in today's medicine. Source of data This review summarizes the current status of tendon treatment and discusses new directions from the point of view of cell-based therapy and regenerative medicine approach. We searched the available literature using PubMed for relevant original articles and reviews. Growing points Identification of tendon cell markers has enabled us to study precisely tendon healing and homeostasis. Clinically, tissue engineering for tendon injuries is an emerging technology comprising elements from the fields of cellular source, scaffold materials, growth factors/cytokines and gene delivering systems. Areas timely for developing research The clinical settings to establish appropriate microenvironment for injured tendons with the combination of these novel cellular- and molecular-based scaffolds will be critical for the treatment. PMID:21729872

  10. The Role of Detraining in Tendon Mechanobiology

    PubMed Central

    Frizziero, Antonio; Salamanna, Francesca; Della Bella, Elena; Vittadini, Filippo; Gasparre, Giuseppe; Nicoli Aldini, Nicolò; Masiero, Stefano; Fini, Milena

    2016-01-01

    Introduction: Several conditions such as training, aging, estrogen deficiency and drugs could affect the biological and anatomo-physiological characteristics of the tendon. Additionally, recent preclinical and clinical studies examined the effect of detraining on tendon, showing alterations in its structure and morphology and in tenocyte mechanobiology. However, few data evaluated the importance that cessation of training might have on tendon. Basically, we do not fully understand how tendons react to a phase of training followed by sudden detraining. Therefore, within this review, we summarize the studies where tendon detraining was examined. Materials and Methods: A descriptive systematic literature review was carried out by searching three databases (PubMed, Scopus and Web of Knowledge) on tendon detraining. Original articles in English from 2000 to 2015 were included. In addition, the search was extended to the reference lists of the selected articles. A public reference manager (www.mendeley.com) was adopted to remove duplicate articles. Results: An initial literature search yielded 134 references (www.pubmed.org: 53; www.scopus.com: 11; www.webofknowledge.com: 70). Fifteen publications were extracted based on the title for further analysis by two independent reviewers. Abstracts and complete articles were after that reviewed to evaluate if they met inclusion criteria. Conclusions: The revised literature comprised four clinical studies and an in vitro and three in vivo reports. Overall, the results showed that tendon structure and properties after detraining are compromised, with an alteration in the tissue structural organization and mechanical properties. Clinical studies usually showed a lesser extent of tendon alterations, probably because preclinical studies permit an in-depth evaluation of tendon modifications, which is hard to perform in human subjects. In conclusion, after a period of sudden detraining (e.g., after an injury), physical activity should

  11. Fibrillins in Tendon

    PubMed Central

    Giusti, Betti; Pepe, Guglielmina

    2016-01-01

    Tendons among connective tissue, mainly collagen, contain also elastic fibers (EF) made of fibrillin 1, fibrillin 2 and elastin that are broadly distributed in tendons and represent 1–2% of the dried mass of the tendon. Only in the last years, studies on structure and function of EF in tendons have been performed. Aim of this review is to revise data on the organization of EF in tendons, in particular fibrillin structure and function, and on the clinical manifestations associated to alterations of EF in tendons. Indeed, microfibrils may contribute to tendon mechanics; therefore, their alterations may cause joint hypermobility and contractures which have been found to be clinical features in patients with Marfan syndrome (MFS) and Beals syndrome. The two diseases are caused by mutations in genes FBN1 and FBN2 encoding fibrillin 1 and fibrillin 2, respectively. PMID:27812333

  12. Rethinking the role of the middle longitudinal fascicle in language and auditory pathways.

    PubMed

    Wang, Yibao; Fernández-Miranda, Juan C; Verstynen, Timothy; Pathak, Sudhir; Schneider, Walter; Yeh, Fang-Cheng

    2013-10-01

    The middle longitudinal fascicle (MdLF) was originally described in the monkey brain as a pathway that interconnects the superior temporal and angular gyri. Only recently have diffusion tensor imaging studies provided some evidence of its existence in humans, with a connectivity pattern similar to that in monkeys and a potential role in the language system. In this study, we combine high-angular-resolution fiber tractography and fiber microdissection techniques to determine the trajectory, cortical connectivity, and a quantitative analysis of the MdLF. Here, we analyze diffusion spectrum imaging (DSI) studies in 6 subjects (subject-specific approach) and in a template of 90 DSI studies (NTU-90 Atlas). Our tractography and microdissection results show that the human MdLF differs significantly from the monkey. Indeed, the human MdLF interconnects the superior temporal gyrus with the superior parietal lobule and parietooccipital region, and has only minor connections with the angular gyrus. On the basis of the roles of these interconnected cortical regions, we hypothesize that, rather than a language-related tract, the MdLF may contribute to the dorsal "where" pathway of the auditory system.

  13. The study of optical properties and proteoglycan content of tendons by PS-OCT

    NASA Astrophysics Data System (ADS)

    Yang, Ying; Rupani, Asha; Weightman, Alan; Wimpenny, Ian; Bagnaninchi, Pierre; Ahearne, Mark

    2011-03-01

    Tendons are load-bearing collagenous tissues consisting mainly of type I collagen and various proteoglycans (PGs) including decorin and versican. It is widely accepted that highly orientated collagen fibers in tendons a play critical role for transferring tensile stress and demonstrate birefringent optical properties. However, the influence that proteoglycans have on the optical properties of tendons is yet to be fully elucidated. Tendinopathy (defined as a syndrome of tendon pain, tenderness and swelling that affects the normal function of the tissue) is a common disease associated with sporting injuries or degeneration. PG's are the essential components of the tendon extracellular matrix; changes in their quantities and compositions have been associated with tendinopathy. In this study, polarization sensitive optical coherence tomography (PS-OCT) has been used to reveal the relationship between proteoglycan content/location and birefringent properties of tendons. Tendons dissected from freshly slaughtered chickens were imaged at regular intervals by PS-OCT and polarizing light microscope during the extraction of PGs or glycosaminoglycans using established protocols (guanidine hydrochloride (GuHCl) or proteinase K solution). The macroscopic and microscopic time lapsed images are complimentary; mutually demonstrating that there was a higher concentration of PG's in the outer sheath region than in the fascicles; and the integrity of the sheath affected extraction process and the OCT birefringence bands. Extraction of PGs using GuHCl disturbed the organization of local collagen bundles, which corresponded to a reduction in the frequency of birefringence bands and the band width by PS-OCT. The feature of OCT penetration depth helped us to define the heterogeneous distribution of PG's in tendon, which was complimented by polarizing light microscopy. The results provide new insight of tendon structure and also demonstrate a great potential for using PS-OCT as a

  14. Effects of prolonged walking on neural and mechanical components of stretch responses in the human soleus muscle

    PubMed Central

    Cronin, Neil J; Ishikawa, Masaki; af Klint, Richard; Komi, Paavo V; Avela, Janne; Sinkjaer, Thomas; Voigt, Michael

    2009-01-01

    After repeated passive stretching, tendinous tissue compliance increases in the human soleus (SOL) muscle–tendon unit. During movement, such changes would have important consequences for neural and mechanical stretch responses. This study examined the existence of such effects in response to a 75 min walking intervention. Eleven healthy subjects walked on a treadmill at 4 km h−1 with a robotic stretch device attached to the left leg. Ultrasonography was used to measure SOL fascicle lengths, and surface EMG activity was recorded in the SOL and tibialis anterior (TA) muscles. Perturbations of 6 deg were imposed at three different measurement intervals: Pre (immediately before the walking intervention), Mid (after approximately 30 min of walking) and Post (immediately after the intervention). Between the Pre–Mid and Mid–Post intervals, subjects walked for 30 min at a gradient of 3%. After the intervention, the amplitude and velocity of fascicle stretch both decreased (by 46 and 59%, respectively; P < 0.001) in response to a constant external perturbation, as did short (33%; P < 0.01) and medium (25%; P < 0.01) latency stretch reflex amplitudes. A faster perturbation elicited at the end of the protocol resulted in a recovery of fascicle stretch velocities and short latency reflex amplitudes to the pre-exercise values. These findings suggest that repeated stretching and shortening of a muscle–tendon unit can induce short-term structural changes in the tendinous tissues during human walking. The data also highlight the effect of these changes on neural feedback from muscle sensory afferents. PMID:19622608

  15. Effects of prolonged walking on neural and mechanical components of stretch responses in the human soleus muscle.

    PubMed

    Cronin, Neil J; Ishikawa, Masaki; Af Klint, Richard; Komi, Paavo V; Avela, Janne; Sinkjaer, Thomas; Voigt, Michael

    2009-09-01

    After repeated passive stretching, tendinous tissue compliance increases in the human soleus (SOL) muscle-tendon unit. During movement, such changes would have important consequences for neural and mechanical stretch responses. This study examined the existence of such effects in response to a 75 min walking intervention. Eleven healthy subjects walked on a treadmill at 4 km h(1) with a robotic stretch device attached to the left leg. Ultrasonography was used to measure SOL fascicle lengths, and surface EMG activity was recorded in the SOL and tibialis anterior (TA) muscles. Perturbations of 6 deg were imposed at three different measurement intervals: Pre (immediately before the walking intervention), Mid (after approximately 30 min of walking) and Post (immediately after the intervention). Between the Pre-Mid and Mid-Post intervals, subjects walked for 30 min at a gradient of 3%. After the intervention, the amplitude and velocity of fascicle stretch both decreased (by 46 and 59%, respectively; P < 0.001) in response to a constant external perturbation, as did short (33%; P < 0.01) and medium (25%; P < 0.01) latency stretch reflex amplitudes. A faster perturbation elicited at the end of the protocol resulted in a recovery of fascicle stretch velocities and short latency reflex amplitudes to the pre-exercise values. These findings suggest that repeated stretching and shortening of a muscle-tendon unit can induce short-term structural changes in the tendinous tissues during human walking. The data also highlight the effect of these changes on neural feedback from muscle sensory afferents.

  16. Soft Pneumatic Actuator Fascicles for High Force and Reliability.

    PubMed

    Robertson, Matthew A; Sadeghi, Hamed; Florez, Juan Manuel; Paik, Jamie

    2017-03-01

    Soft pneumatic actuators (SPAs) are found in mobile robots, assistive wearable devices, and rehabilitative technologies. While soft actuators have been one of the most crucial elements of technology leading the development of the soft robotics field, they fall short of force output and bandwidth requirements for many tasks. In addition, other general problems remain open, including robustness, controllability, and repeatability. The SPA-pack architecture presented here aims to satisfy these standards of reliability crucial to the field of soft robotics, while also improving the basic performance capabilities of SPAs by borrowing advantages leveraged ubiquitously in biology; namely, the structured parallel arrangement of lower power actuators to form the basis of a larger and more powerful actuator module. An SPA-pack module consisting of a number of smaller SPAs will be studied using an analytical model and physical prototype. Experimental measurements show an SPA pack to generate over 112 N linear force, while the model indicates the benefit of parallel actuator grouping over a geometrically equivalent single SPA scale as an increasing function of the number of individual actuators in the group. For a module of four actuators, a 23% increase in force production over a volumetrically equivalent single SPA is predicted and validated, while further gains appear possible up to 50%. These findings affirm the advantage of utilizing a fascicle structure for high-performance soft robotic applications over existing monolithic SPA designs. An example of high-performance soft robotic platform will be presented to demonstrate the capability of SPA-pack modules in a complete and functional system.

  17. Soft Pneumatic Actuator Fascicles for High Force and Reliability

    PubMed Central

    Robertson, Matthew A.; Sadeghi, Hamed; Florez, Juan Manuel

    2017-01-01

    Abstract Soft pneumatic actuators (SPAs) are found in mobile robots, assistive wearable devices, and rehabilitative technologies. While soft actuators have been one of the most crucial elements of technology leading the development of the soft robotics field, they fall short of force output and bandwidth requirements for many tasks. In addition, other general problems remain open, including robustness, controllability, and repeatability. The SPA-pack architecture presented here aims to satisfy these standards of reliability crucial to the field of soft robotics, while also improving the basic performance capabilities of SPAs by borrowing advantages leveraged ubiquitously in biology; namely, the structured parallel arrangement of lower power actuators to form the basis of a larger and more powerful actuator module. An SPA-pack module consisting of a number of smaller SPAs will be studied using an analytical model and physical prototype. Experimental measurements show an SPA pack to generate over 112 N linear force, while the model indicates the benefit of parallel actuator grouping over a geometrically equivalent single SPA scale as an increasing function of the number of individual actuators in the group. For a module of four actuators, a 23% increase in force production over a volumetrically equivalent single SPA is predicted and validated, while further gains appear possible up to 50%. These findings affirm the advantage of utilizing a fascicle structure for high-performance soft robotic applications over existing monolithic SPA designs. An example of high-performance soft robotic platform will be presented to demonstrate the capability of SPA-pack modules in a complete and functional system. PMID:28289573

  18. Ultrasound-Based Tendon Micromorphology Predicts Mechanical Characteristics of Degenerated Tendons.

    PubMed

    Kulig, Kornelia; Chang, Yu-Jen; Winiarski, Slawomir; Bashford, Gregory R

    2016-03-01

    The purpose of this study was to explore the relationship between tendon micro-morphology quantified from a sonogram and tendon mechanical characteristics measured in vivo. Nineteen adults (nine with unilateral Achilles tendinosis) participated. A commercial ultrasound scanner was used to capture longitudinal B-mode ultrasound images from the mid-portion of bilateral Achilles tendons and a custom image analysis program was used to analyze the spatial frequency content of manually defined regions of interest; in particular, the average peak spatial frequency of the regions of interest was acquired. In addition, a dynamometer and a motion analysis system indirectly measured the tendon mechanical (stiffness) and material (elastic modulus) properties. The peak spatial frequency correlated with tendon stiffness (r = 0.74, p = 0.02) and elastic modulus (r = 0.65, p = 0.05) in degenerated tendons, but not healthy tendons. This is the first study relating the mechanical characteristics of degenerated human Achilles tendon using a non-invasive micro-morphology analysis approach.

  19. Relative fascicle excursion effects on dynamic strength generation during gait in children with cerebral palsy.

    PubMed

    Martín Lorenzo, T; Lerma Lara, S; Martínez-Caballero, I; Rocon, E

    2015-10-01

    Evaluation of muscle structure gives us a better understanding of how muscles contribute to force generation which is significantly altered in children with cerebral palsy (CP). While most muscle structure parameters have shown to be significantly correlated to different expressions of strength development in children with CP and typically developing (TD) children, conflicting results are found for muscle fascicle length. Muscle fascicle length determines muscle excursion and velocity, and contrary to what might be expected, correlations of fascicle length to rate of force development have not been found for children with CP. The lack of correlation between muscle fascicle length and rate of force development in children with CP could be due, on the one hand, to the non-optimal joint position adopted for force generation on the isometric strength tests as compared to the position of TD children. On the other hand, the lack of correlation could be due to the erroneous assumption that muscle fascicle length is representative of sarcomere length. Thus, the relationship between muscle architecture parameters reflecting sarcomere length, such as relative fascicle excursions and dynamic power generation, should be assessed. Understanding of the underlying mechanisms of weakness in children with CP is key for individualized prescription and assessment of muscle-targeted interventions. Findings could imply the detection of children operating on the descending limb of the sarcomere length-tension curve, which in turn might be at greater risk of developing crouch gait. Furthermore, relative muscle fascicle excursions could be used as a predictive variable of outcomes related to crouch gait prevention treatments such as strength training.

  20. Low-frequency pulsed electromagnetic fields significantly improve time of closure and proliferation of human tendon fibroblasts

    PubMed Central

    2014-01-01

    Background The promotion of the healing process following musculoskeletal injuries comprises growth factor signalling, migration, proliferation and apoptosis of cells. If these processes could be modulated, the healing of tendon tissue may be markedly enhanced. Here, we report the use of the Somagen™ device, which is certified for medical use according to European laws. It generates low-frequency pulsed electromagnetic fields that trigger effects of a nature that are yet to be determined. Methods A 1.5-cm wide, linear scrape was introduced into patellar tendon fibroblast cultures (N = 5 donors). Treatment was carried out every second day. The regimen was applied three times in total with 30 minutes comprising pulsed electromagnetic field packages with two fundamental frequencies (10 minutes of 33 Hz, 20 minutes of 7.8 Hz). Control cells remained untreated. All samples were analyzed for gap closure time, proliferation and apoptosis one week after induction of the scrape wound. Results The mean time for bridging the gap in the nontreated cells was 5.05 ± 0.33 days, and in treated cells, it took 3.35 ± 0.38 days (P <0.001). For cell cultures with scrape wounds, a mean value for BrdU incorporation of OD = 0.70 ± 0.16 was found. Whereas low-frequency pulsed electromagnetic fields treated samples showed OD = 1.58 ± 0.24 (P <0.001). However, the percentage of apoptotic cells did not differ between the two groups. Conclusions Our data demonstrate that low-frequency pulsed electromagnetic fields emitted by the Somagen™ device influences the in vitro wound healing of patellar tendon fibroblasts and, therefore, possibly increases wound healing potential. PMID:24996421

  1. Tendon and ligament imaging

    PubMed Central

    Hodgson, R J; O'Connor, P J; Grainger, A J

    2012-01-01

    MRI and ultrasound are now widely used for the assessment of tendon and ligament abnormalities. Healthy tendons and ligaments contain high levels of collagen with a structured orientation, which gives rise to their characteristic normal imaging appearances as well as causing particular imaging artefacts. Changes to ligaments and tendons as a result of disease and injury can be demonstrated using both ultrasound and MRI. These have been validated against surgical and histological findings. Novel imaging techniques are being developed that may improve the ability of MRI and ultrasound to assess tendon and ligament disease. PMID:22553301

  2. A passive exoskeleton with artificial tendons: design and experimental evaluation.

    PubMed

    van Dijk, Wietse; van der Kooij, Herman; Hekman, Edsko

    2011-01-01

    We developed a passive exoskeleton that was designed to minimize joint work during walking. The exoskeleton makes use of passive structures, called artificial tendons, acting in parallel with the leg. Artificial tendons are elastic elements that are able to store and redistribute energy over the human leg joints. The elastic characteristics of the tendons have been optimized to minimize the mechanical work of the human leg joints. In simulation the maximal reduction was 40 percent. The performance of the exoskeleton was evaluated in an experiment in which nine subjects participated. Energy expenditure and muscle activation were measured during three conditions: Normal walking, walking with the exoskeleton without artificial tendons, and walking with the exoskeleton with the artificial tendons. Normal walking was the most energy efficient. While walking with the exoskeleton, the artificial tendons only resulted in a negligibly small decrease in energy expenditure.

  3. Negative participation of the left posterior fascicle in the reentry circuit of verapamil-sensitive idiopathic left ventricular tachycardia.

    PubMed

    Morishima, Itsuro; Nogami, Akihiko; Tsuboi, Hideyuki; Sone, Takahito

    2012-05-01

    Left posterior fascicle and idiopathic Left VT. The left posterior fascicle may be a bystander of the circuit of verapamil-sensitive idiopathic left ventricular tachycardia. During ventricular tachycardia (VT), 3 sequences of potentials were seen at the left posterior septum: diastolic Purkinje potentials propagating from base to apex and presystolic left posterior fascicular potentials and systolic left ventricular (LV) myocardial potentials propagating in the reverse direction. Selective capture of the left posterior fascicle by the sinus beat did not affect the VT cycle length. Entrainment pacing revealed that the retrograde limb of the circuit was not the left posterior fascicle, but the LV myocardium.

  4. Relationship Between Sprint Performance of Front Crawl Swimming and Muscle Fascicle Length in Young Swimmers

    PubMed Central

    Nasirzade, Alireza; Ehsanbakhsh, Alireza; Ilbeygi, Saeed; Sobhkhiz, Azadeh; Argavani, Hamed; Aliakbari, Mehdi

    2014-01-01

    The purpose of this study was to investigate the relationship between 25-m sprint front crawl swimming performance and muscle fascicle length in young male swimmers. 23 swimmers were selected and divided into two groups according to their best records of 25-m sprint performance: 14.6-15.7 sec (S1, n = 11) and 15.8-17 sec (S2, n = 12). Muscle thickness and pennation angle of Biceps Brachii (BB; only muscle thickness), Triceps Brachii (TB), Vastus Lateralis (VL), Gastrocnemius Medialis (GM) and Lateralis (GL) muscles were measured by B-mode ultrasonography, and fascicle length was estimated. Although, there was no significant differences between groups in anthropometrical parameter as standing height, body mass, arm length, thigh length and leg length (p < 0.001), however, S1 significantly had a greater muscle thickness in VL, GL, and TB muscles (p < 0.05). Pennation angle only in TB was significantly smaller in S1 (p < 0.05). S1 in VL, GL, and TB muscles significantly had greater absolute fascicle length and in VL and TB muscles had relatively (relative to limb length) greater fascicle length (p < 0.05). Moreover, there was a significant relationship between sprint swimming time and absolute and relative fascicle length in VL (absolute: r = -0.49 and relative: r = -0.43, both p < 0.05) and GL (absolute: r = -0.47 and relative: r = -0.42, both p < 0.05). Potentially, it seems that fascicle geometry developed in muscles of faster young swimmers to help them to perform their high speed movement. Key Points This study investigated the relationship between muscle fascicle length and sprint front crawl performance in young male swimmers. It seems that young swimmers with faster front crawl sprint swimming performance trend to have smaller pennation angle and greater absolute and relative fascicle length (relative to limb length) in their locomotor muscles. Potentially, fascicle geometry developed in faster swimmers to help them to perform higher speed movement via higher

  5. Relationship between sprint performance of front crawl swimming and muscle fascicle length in young swimmers.

    PubMed

    Nasirzade, Alireza; Ehsanbakhsh, Alireza; Ilbeygi, Saeed; Sobhkhiz, Azadeh; Argavani, Hamed; Aliakbari, Mehdi

    2014-09-01

    The purpose of this study was to investigate the relationship between 25-m sprint front crawl swimming performance and muscle fascicle length in young male swimmers. 23 swimmers were selected and divided into two groups according to their best records of 25-m sprint performance: 14.6-15.7 sec (S1, n = 11) and 15.8-17 sec (S2, n = 12). Muscle thickness and pennation angle of Biceps Brachii (BB; only muscle thickness), Triceps Brachii (TB), Vastus Lateralis (VL), Gastrocnemius Medialis (GM) and Lateralis (GL) muscles were measured by B-mode ultrasonography, and fascicle length was estimated. Although, there was no significant differences between groups in anthropometrical parameter as standing height, body mass, arm length, thigh length and leg length (p < 0.001), however, S1 significantly had a greater muscle thickness in VL, GL, and TB muscles (p < 0.05). Pennation angle only in TB was significantly smaller in S1 (p < 0.05). S1 in VL, GL, and TB muscles significantly had greater absolute fascicle length and in VL and TB muscles had relatively (relative to limb length) greater fascicle length (p < 0.05). Moreover, there was a significant relationship between sprint swimming time and absolute and relative fascicle length in VL (absolute: r = -0.49 and relative: r = -0.43, both p < 0.05) and GL (absolute: r = -0.47 and relative: r = -0.42, both p < 0.05). Potentially, it seems that fascicle geometry developed in muscles of faster young swimmers to help them to perform their high speed movement. Key PointsThis study investigated the relationship between muscle fascicle length and sprint front crawl performance in young male swimmers.It seems that young swimmers with faster front crawl sprint swimming performance trend to have smaller pennation angle and greater absolute and relative fascicle length (relative to limb length) in their locomotor muscles.Potentially, fascicle geometry developed in faster swimmers to help them to perform higher speed movement via higher

  6. Elastographic characteristics of the metacarpal tendons in horses without clinical evidence of tendon injury.

    PubMed

    Lustgarten, Meghann; Redding, W Rich; Labens, Raphael; Morgan, Michel; Davis, Weston; Seiler, Gabriela S

    2014-01-01

    Tendon and ligament injuries are common causes of impaired performance in equine athletes. Gray-scale ultrasonography is the current standard method for diagnosing and monitoring these injuries, however this modality only provides morphologic information. Elastography is an ultrasound technique that allows detection and measurement of tissue strain, and may provide valuable mechanical information about equine tendon and ligament injuries. The purpose of this study was to determine the feasibility, reproducibility, and repeatability of elastography; and to describe elastographic characteristics of metacarpal tendons in sound horses. Nineteen legs for 17 clinically sound horses without evidence of musculoskeletal pathology were included. Elastographic images of the superficial and deep digital flexor tendons and the branches of the suspensory ligament (tendon of the interosseous muscle) were described quantitatively and qualitatively. There was no statistically significant difference between operators (P = 0.86) nor within operators (P = 0.93). For qualitative assessments, reproducibility (0.46) was moderate and repeatability (0.78) was good. Similar to human Achilles tendons, equine tendons were classified as predominantly hard using elastography. There was no statistically significant difference in stiffness of the flexor tendons (P = 0.96). No significant difference in stiffness was found with altered leg position during standing (P = 0.84) and while nonweight bearing (P = 0.61). The flexor tendons were softer when imaged in longitudinal versus transverse planes (P < 0.01) however, the suspensory branches were not (P = 0.67). Findings supported future clinical application of elastography as a noninvasive "stall-side" imaging modality for evaluation of the tendons and ligaments of the distal forelimb in horses.

  7. Distal Biceps Tendon Rupture

    DTIC Science & Technology

    2010-06-01

    distal tendon. Although these findings overlap with those seen in tendinopathy , the presence of bone marrow edema at the radial tuberosity and fluid in...the bicipitoradial bursa suggests a partial tear rather than tendinopathy .3 When the distal biceps tendon tear is complete, MR imaging shows

  8. Forefoot tendon transfers.

    PubMed

    Veljkovic, Andrea; Lansang, Edward; Lau, Johnny

    2014-03-01

    Flexible forefoot deformities, such as hallux varus, clawed hallux, hammer toes, and angular lesser toe deformities, can be treated effectively with tendon transfers. Based on the presentation of the flexible forefoot deformities, tendon transfers can be used as the primary treatment or as adjuncts to bony procedures when there are components of fixed deformities.

  9. Effects of leg muscle tendon vibration on group Ia and group II reflex responses to stance perturbation in humans

    PubMed Central

    Bove, Marco; Nardone, Antonio; Schieppati, Marco

    2003-01-01

    Stretching the soleus (Sol) muscle during sudden toe-up rotations of the supporting platform in a standing subject evokes a short-latency response (SLR) and a medium-latency response (MLR). The aim of the present investigation was to further explore the afferent and spinal pathways mediating the SLR and MLR in lower limb muscles by means of tendon vibration. In seven subjects, toe-up or toe-down rotations were performed under: (1) control, (2) continuous bilateral vibration at 90 Hz of Achilles' tendon or tibialis anterior (TA) tendon, and (3) post-vibration conditions. Sol and TA background EMG activity and reflex responses were bilaterally recorded and analysed. Toe-up rotations induced SLRs and MLRs in Sol at average latencies of 40 and 66 ms, respectively. During vibration, the latency of both responses increased by about 2 ms. The area of the SLR significantly decreased during vibration, regardless of the underlying background activity, and almost returned to control value post-vibration. The area of Sol MLR was less influenced by vibration than SLR, the reduction being negligible with relatively high background activity. However, contrary to SLR, MLR was even more reduced post-vibration. Toe-down rotations induced no SLR in the TA, while a MLR was evoked at about 81 ms. The area of TA MLR decreased slightly during vibration but much more post-vibration. SLRs and MLRs were differently affected by changing the vibration frequency to 30 Hz: vibration had a negligible effect on the SLR, but still produced a significant effect on the MLR. The independence from the background EMG of the inhibitory effect of vibration upon the SLR suggests that vibration removes a constant amount of the Ia afferent input. This can be accounted for by either presynaptic inhibition of group Ia fibres or a ‘busy-line' phenomenon. The differential effect of vibration on SLRs and MLRs is compatible with the notions that spindle primaries have a higher sensitivity to vibration than

  10. Fetal development of the pulley for muscle insertion tendons: A review and new findings related to the tensor tympani tendon.

    PubMed

    Rodríguez-Vázquez, Jose Francisco; Honkura, Yohei; Katori, Yukio; Murakami, Gen; Abe, Hiroshi

    2017-01-01

    The existence of hard tissue pulleys that act to change the direction of a muscle insertion tendon is well known in the human body. These include (1) the trochlea for the extraocular obliquus superior muscle, (2) the pterygoid hamulus for the tensor veli palatini muscle, (3) the deep sulcus on the plantar aspect of the cuboid bone for the peroneus longus tendon, (4) the lesser sciatic notch for the obturator internus muscle, and (5) the bony trochleariformis process for the tensor tympani muscle tendon. In addition, (6) the stapedius muscle tendon shows a lesser or greater angulation at the pyramidal eminence of the temporal bone. Our recent studies have shown that the development of pulleys Nos. 1 and 2 can be explained by a change in the topographical relationship between the pulley and the tendon, that of pulley No. 3 by the rapidly growing calcaneus pushing the tendon, and that of pulley No. 4 by migration of the insertion along the sciatic nerve and gluteus medius tendon. Therefore, in Nos. 1-4, an initially direct tendon curves secondarily and obtains an attachment to the pulley. In case No. 6, the terminal part of the stapedius tendon originates secondarily from the interzone mesenchymal tissue of the incudostapedial joint. In the case of pulley No. 5, we newly demonstrated that its initial phase of development was similar to No. 6, but the tensor tympani tendon achieved a right-angled turn under guidance by a specific fibrous tissue and it migrated along the growing malleus manubrium.

  11. The tibialis posterior tendon.

    PubMed

    Lhoste-Trouilloud, A

    2012-02-01

    The tibialis posterior tendon is the largest and anteriormost tendon in the medial ankle. It produces plantar flexion and supination of the ankle and stabilizes the plantar vault. Sonographic assessment of this tendon is done with high-frequency, linear-array transducers; an optimal examination requires transverse retromalleolar, longitudinal retromalleolar, and distal longitudinal scans, as well as dynamic studies. Disorders of the posterior tibial tendon include chronic tendinopathy with progressive rupture, tenosynovitis, acute rupture, dislocation and instability, enthesopathies. The most common lesion is a progressive "chewing gum" lesion that develops in a setting of chronic tendinopathy; it is usually seen in overweight women over 50 years of age with valgus flat feet. Medial ankle pain must also be carefully investigated, and the presence of instability assessed with dynamic maneuvers (forced inversion, or dorsiflexion) of the foot. Sonography plays an important role in the investigation of disorders involving the posterior tibial tendon.

  12. Ethanol treatment of tendon allografts: a potential HIV inactivating procedure.

    PubMed

    Anastasescou, M; Cornu, O; Banse, X; König, J; Hassoun, A; Delloye, C

    1998-01-01

    The penetration rate of ethanol in human tendons was studied to in order to define the conditions which were necessary to achieve an inactivating concentration against the Human Immunodeficiency Virus (HIV) within the tendon. The rate of alcohol penetration was found to be slow and did not differ with different types of tendons. An average ethanol concentration of 14% (v/v) was measured in human tendons after they had been immersed for 2 h in 70% (v/v) ethanol, and a concentration of 19% (v/v) was reached after 3 h. Ethanol immersion of human tendons may represent an additional safety procedure in inactivating the HIV virus provided the duration is at least 3 h.

  13. A mathematical framework for the registration and analysis of multi-fascicle models for population studies of the brain microstructure.

    PubMed

    Taquet, Maxime; Scherrer, Benoit; Commowick, Olivier; Peters, Jurriaan M; Sahin, Mustafa; Macq, Benoit; Warfield, Simon K

    2014-02-01

    Diffusion tensor imaging (DTI) is unable to represent the diffusion signal arising from multiple crossing fascicles and freely diffusing water molecules. Generative models of the diffusion signal, such as multi-fascicle models, overcome this limitation by providing a parametric representation for the signal contribution of each population of water molecules. These models are of great interest in population studies to characterize and compare the brain microstructural properties. Central to population studies is the construction of an atlas and the registration of all subjects to it. However, the appropriate definition of registration and atlasing methods for multi-fascicle models have proven challenging. This paper proposes a mathematical framework to register and analyze multi-fascicle models. Specifically, we define novel operators to achieve interpolation, smoothing and averaging of multi-fascicle models. We also define a novel similarity metric to spatially align multi-fascicle models. Our framework enables simultaneous comparisons of different microstructural properties that are confounded in conventional DTI. The framework is validated on multi-fascicle models from 24 healthy subjects and 38 patients with tuberous sclerosis complex, 10 of whom have autism. We demonstrate the use of the multi-fascicle models registration and analysis framework in a population study of autism spectrum disorder.

  14. Evidence that interfibrillar load transfer in tendon is supported by small diameter fibrils and not extrafibrillar tissue components.

    PubMed

    Szczesny, Spencer E; Fetchko, Kristen L; Dodge, George R; Elliott, Dawn M

    2017-01-10

    Collagen fibrils in tendon are believed to be discontinuous and transfer tensile loads through shear forces generated during interfibrillar sliding. However, the structures that transmit these interfibrillar forces are unknown. Various extrafibrillar tissue components (e.g., glycosaminoglycans, collagens XII and XIV) have been suggested to transmit interfibrillar loads by bridging collagen fibrils. Alternatively, collagen fibrils may interact directly through physical fusions and interfibrillar branching. The objective of this study was to test whether extrafibrillar proteins are necessary to transmit load between collagen fibrils or if interfibrillar load transfer is accomplished directly by the fibrils themselves. Trypsin digestions were used to remove a broad spectrum of extrafibrillar proteins and measure their contribution to the multiscale mechanics of rat tail tendon fascicles. Additionally, images obtained from serial block-face scanning electron microscopy were used to determine the three-dimensional fibrillar organization in tendon fascicles and identify any potential interfibrillar interactions. While trypsin successfully removed several extrafibrillar tissue components, there was no change in the macroscale fascicle mechanics or fibril:tissue strain ratio. Furthermore, the imaging data suggested that a network of smaller diameter fibrils (<150 nm) wind around and fuse with their neighboring larger diameter fibrils. These findings demonstrate that interfibrillar load transfer is not supported by extrafibrillar tissue components and support the hypothesis that collagen fibrils are capable of transmitting loads themselves. Conclusively determining how fibrils bear load within tendon is critical for identifying the mechanisms that impair tissue function with degeneration and for restoring tissue properties via cell-mediated regeneration or engineered tissue replacements. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop

  15. Tendon gradient mineralization for tendon to bone interface integration.

    PubMed

    Qu, Jin; Thoreson, Andrew R; Chen, Qingshan; An, Kai-Nan; Amadio, Peter C; Zhao, Chunfeng

    2013-11-01

    Tendon-to-bone integration is a great challenge for tendon or ligament reconstruction regardless of use of autograft or allograft tendons. We mineralized the tendon, thus transforming the tendon-to-bone into a "bone-to-bone" interface for healing. Sixty dog flexor digitorum profundus (FDP) tendons were divided randomly into five groups: (1) normal FDP tendon, (2) CaP (non-extraction and mineralization without fetuin), (3) CaPEXT (Extraction by Na2 HPO4 and mineralization without fetuin), (4) CaPFetuin (non-extraction and mineralization with fetuin), and (5) CaPEXTFetuin (extraction and mineralization with fetuin). The calcium and phosphate content significantly increased in tendons treated with combination of extraction and fetuin compared to the other treatments. Histology also revealed a dense mineral deposition throughout the tendon outer layers and penetrated into the tendon to a depth of 200 µm in a graded manner. Compressive moduli were significantly lower in the four mineralized groups compared with normal control group. No significant differences in maximum failure strength or stiffness were found in the suture pull-out test among all groups. Mineralization of tendon alters the interface from tendon to bone into mineralized tendon to bone, which may facilitate tendon-to-bone junction healing following tendon or ligament reconstruction.

  16. 21 CFR 888.3025 - Passive tendon prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Passive tendon prosthesis. 888.3025 Section 888.3025 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... flexor tendon of the hand. The device is implanted for a period of 2 to 6 months to aid growth of a...

  17. 21 CFR 888.3025 - Passive tendon prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Passive tendon prosthesis. 888.3025 Section 888.3025 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... flexor tendon of the hand. The device is implanted for a period of 2 to 6 months to aid growth of a...

  18. Combined DTI Tractography and Functional MRI Study of the Language Connectome in Healthy Volunteers: Extensive Mapping of White Matter Fascicles and Cortical Activations

    PubMed Central

    Schneider, Fabien; Boutet, Claire; Jean, Betty

    2016-01-01

    Despite a better understanding of brain language organization into large-scale cortical networks, the underlying white matter (WM) connectivity is still not mastered. Here we combined diffusion tensor imaging (DTI) fiber tracking (FT) and language functional magnetic resonance imaging (fMRI) in twenty healthy subjects to gain new insights into the macroscopic structural connectivity of language. Eight putative WM fascicles for language were probed using a deterministic DTI-FT technique: the arcuate fascicle (AF), superior longitudinal fascicle (SLF), uncinate fascicle (UF), temporo-occipital fascicle, inferior fronto-occipital fascicle (IFOF), middle longitudinal fascicle (MdLF), frontal aslant fascicle and operculopremotor fascicle. Specific measurements (i.e. volume, length, fractional anisotropy) and precise cortical terminations were derived for each WM fascicle within both hemispheres. Connections between these WM fascicles and fMRI activations were studied to determine which WM fascicles are related to language. WM fascicle volumes showed asymmetries: leftward for the AF, temporoparietal segment of SLF and UF, and rightward for the frontoparietal segment of the SLF. The lateralization of the AF, IFOF and MdLF extended to differences in patterns of anatomical connections, which may relate to specific hemispheric abilities. The leftward asymmetry of the AF was correlated to the leftward asymmetry of fMRI activations, suggesting that the lateralization of the AF is a structural substrate of hemispheric language dominance. We found consistent connections between fMRI activations and terminations of the eight WM fascicles, providing a detailed description of the language connectome. WM fascicle terminations were also observed beyond fMRI-confirmed language areas and reached numerous cortical areas involved in different functional brain networks. These findings suggest that the reported WM fascicles are not exclusively involved in language and might be related to

  19. Tendon overload results in alterations in cell shape and increased markers of inflammation and matrix degradation.

    PubMed

    Thorpe, C T; Chaudhry, S; Lei, I I; Varone, A; Riley, G P; Birch, H L; Clegg, P D; Screen, H R C

    2015-08-01

    Tendon injury is thought to involve both damage accumulation within the matrix and an accompanying cell response. While several studies have characterized cell and matrix response in chronically injured tendons, few have assessed the initial response of tendon to overload-induced damage. In this study, we assessed cell response to cyclic loading. Fascicle bundles from the equine superficial digital flexor tendon were exposed to cyclic loading in vitro, designed to mimic a bout of high-intensity exercise. Changes in cell morphology and protein-level alterations in markers of matrix inflammation and degradation were investigated. Loading resulted in matrix damage, which was accompanied by cells becoming rounder. The inflammatory markers cyclooxygenase-2 and interleukin-6 were increased in loaded samples, as were matrix metalloproteinase-13 and the collagen degradation marker C1,2C. These results indicate upregulation of inflammatory and degradative pathways in response to overload-induced in vitro, which may be initiated by alterations in cell strain environment because of localized matrix damage. This provides important information regarding the initiation of tendinopathy, suggesting that inflammation may play an important role in the initial cell response to tendon damage. Full understanding of the early tenocyte response to matrix damage is critical in order to develop effective treatments for tendinopathy.

  20. Zonal variation in primary cilia elongation correlates with localized biomechanical degradation in stress deprived tendon.

    PubMed

    Rowson, Daniel; Knight, Martin M; Screen, Hazel R C

    2016-12-01

    Tenocytes express primary cilia, which elongate when tendon is maintained in the absence of biomechanical load. Previous work indicates differences in the morphology and metabolism of the tenocytes in the tendon fascicular matrix (FM) and the inter-fascicular matrix (IFM). This study tests the hypothesis that primary cilia in these two regions respond differently to stress deprivation and that this is associated with differences in the biomechanical degradation of the extracellular matrix. Rat tail tendon fascicles were examined over a 7-day period of either stress deprivation or static load. Seven days of stress deprivation induced cilia elongation in both regions. However, elongation was greater in the IFM compared to the FM. Stress deprivation also induced a loss of biomechanical integrity, primarily in the IFM. Static loading reduced both the biomechanical degradation and cilia elongation. The different responses to stress deprivation in the two tendon regions are likely to be important for the aetiology of tendinopathy. Furthermore, these data suggest that primary cilia elongate in response to biomechanical degradation rather than simply the removal of load. This response to degradation is likely to have important consequences for cilia signalling in tendon and as well as in other connective tissues. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 34:2146-2153, 2016.

  1. Zonal variation in primary cilia elongation correlates with localized biomechanical degradation in stress deprived tendon

    PubMed Central

    Rowson, Daniel; Screen, Hazel R.C.

    2016-01-01

    ABSTRACT Tenocytes express primary cilia, which elongate when tendon is maintained in the absence of biomechanical load. Previous work indicates differences in the morphology and metabolism of the tenocytes in the tendon fascicular matrix (FM) and the inter‐fascicular matrix (IFM). This study tests the hypothesis that primary cilia in these two regions respond differently to stress deprivation and that this is associated with differences in the biomechanical degradation of the extracellular matrix. Rat tail tendon fascicles were examined over a 7‐day period of either stress deprivation or static load. Seven days of stress deprivation induced cilia elongation in both regions. However, elongation was greater in the IFM compared to the FM. Stress deprivation also induced a loss of biomechanical integrity, primarily in the IFM. Static loading reduced both the biomechanical degradation and cilia elongation. The different responses to stress deprivation in the two tendon regions are likely to be important for the aetiology of tendinopathy. Furthermore, these data suggest that primary cilia elongate in response to biomechanical degradation rather than simply the removal of load. This response to degradation is likely to have important consequences for cilia signalling in tendon and as well as in other connective tissues. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 34:2146–2153, 2016. PMID:26969839

  2. Inflamed shoulder tendons (image)

    MedlinePlus

    Tearing and inflammation of the tendons of the shoulder muscles can occur in sports which require the ... pitching, swimming, and lifting weights. Most often the shoulder will heal if a break is taken from ...

  3. Proximal Biceps Tendonitis

    MedlinePlus

    ... teens, biceps tendonitis is usually an overuse injury. Baseball pitchers, swimmers, tennis players, and people who have ... But if you swim or play tennis or baseball, that might not be an option! If your ...

  4. Tendon vs. ligament (image)

    MedlinePlus

    ... the eyeball. A tendon serves to move the bone or structure. A ligament is a fibrous connective tissue which attaches bone to bone, and usually serves to hold structures together and keep them stable.

  5. Polarization-resolved SHG microscopy of rat-tail tendon with controlled mechanical strain

    NASA Astrophysics Data System (ADS)

    Gusachenko, I.; Goulam Houssen, Y.; Tran, V.; Allain, J.-M.; Schanne-Klein, M.-C.

    2013-06-01

    We combined polarization-resolved SHG microscopy with mechanical assays in rat-tail-tendon and measured collagen remodeling upon controlled stretching. This approach aimed to analyze the relationship between macroscopic response and sub-micrometer scale organization of collagen fibrils. We observed a straightening of the crimps followed by a sliding of the fibrils with increasing stretching of the tendon fascicles. Polarization resolution of the SHG images provided complementary information about the orientation dispersion of collagen fibrils within the focal volume and enabled monitoring of collagen remodeling at the sub-micrometer scale. Our approach can be readily generalized to other tissues and should bring new valuable information about biomechanics of microstructured tissues.

  6. The promoting effect of pentadecapeptide BPC 157 on tendon healing involves tendon outgrowth, cell survival, and cell migration.

    PubMed

    Chang, Chung-Hsun; Tsai, Wen-Chung; Lin, Miao-Sui; Hsu, Ya-Hui; Pang, Jong-Hwei Su

    2011-03-01

    Pentadecapeptide BPC 157, composed of 15 amino acids, is a partial sequence of body protection compound (BPC) that is discovered in and isolated from human gastric juice. Experimentally it has been demonstrated to accelerate the healing of many different wounds, including transected rat Achilles tendon. This study was designed to investigate the potential mechanism of BPC 157 to enhance healing of injured tendon. The outgrowth of tendon fibroblasts from tendon explants cultured with or without BPC 157 was examined. Results showed that BPC 157 significantly accelerated the outgrowth of tendon explants. Cell proliferation of cultured tendon fibroblasts derived from rat Achilles tendon was not directly affected by BPC 157 as evaluated by MTT assay. However, the survival of BPC 157-treated cells was significantly increased under the H(2)O(2) stress. BPC 157 markedly increased the in vitro migration of tendon fibroblasts in a dose-dependent manner as revealed by transwell filter migration assay. BPC 157 also dose dependently accelerated the spreading of tendon fibroblasts on culture dishes. The F-actin formation as detected by FITC-phalloidin staining was induced in BPC 157-treated fibroblasts. The protein expression and activation of FAK and paxillin were determined by Western blot analysis, and the phosphorylation levels of both FAK and paxillin were dose dependently increased by BPC 157 while the total amounts of protein was unaltered. In conclusion, BPC 157 promotes the ex vivo outgrowth of tendon fibroblasts from tendon explants, cell survival under stress, and the in vitro migration of tendon fibroblasts, which is likely mediated by the activation of the FAK-paxillin pathway.

  7. Tendon progenitor cells in injured tendons have strong chondrogenic potential: the CD105-negative subpopulation induces chondrogenic degeneration.

    PubMed

    Asai, Shuji; Otsuru, Satoru; Candela, Maria Elena; Cantley, Leslie; Uchibe, Kenta; Hofmann, Ted J; Zhang, Kairui; Wapner, Keith L; Soslowsky, Louis J; Horwitz, Edwin M; Enomoto-Iwamoto, Motomi

    2014-12-01

    To study the cellular mechanism of the tendon repair process, we used a mouse Achilles tendon injury model to focus on the cells recruited to the injured site. The cells isolated from injured tendon 1 week after the surgery and uninjured tendons contained the connective tissue progenitor populations as determined by colony-forming capacity, cell surface markers, and multipotency. When the injured tendon-derived progenitor cells (inTPCs) were transplanted into injured Achilles tendons, they were not only integrated in the regenerating area expressing tenogenic phenotype but also trans-differentiated into chondrogenic cells in the degenerative lesion that underwent ectopic endochondral ossification. Surprisingly, the micromass culture of the inTPCs rapidly underwent chondrogenic differentiation even in the absence of exogenous bone morphogenetic proteins or TGFβs. The cells isolated from human ruptured tendon tissues also showed connective tissue progenitor properties and exhibited stronger chondrogenic ability than bone marrow stromal cells. The mouse inTPCs contained two subpopulations one positive and one negative for CD105, a coreceptor of the TGFβ superfamily. The CD105-negative cells showed superior chondrogenic potential in vitro and induced larger chondroid degenerative lesions in mice as compared to the CD105-positive cells. These findings indicate that tendon progenitor cells are recruited to the injured site of tendons and have a strong chondrogenic potential and that the CD105-negative population of these cells would be the cause for chondroid degeneration in injured tendons. The newly identified cells recruited to the injured tendon may provide novel targets to develop therapeutic strategies to facilitate tendon repair.

  8. Influences of Fascicle Length During Isometric Training on Improvement of Muscle Strength.

    PubMed

    Tanaka, Hiroki; Ikezoe, Tome; Umehara, Jun; Nakamura, Masatoshi; Umegaki, Hiroki; Kobayashi, Takuya; Nishishita, Satoru; Fujita, Kosuke; Araki, Kojiro; Ichihashi, Noriaki

    2016-11-01

    Tanaka, H, Ikezoe, T, Umehara, J, Nakamura, M, Umegaki, H, Kobayashi, T, Nishishita, S, Fujita, K, Araki, K, and Ichihashi, N. Influences of fascicle length during isometric training on improvement of muscle strength. J Strength Cond Res 30(11): 3249-3255, 2016-This study investigated whether low-intensity isometric training would elicit a greater improvement in maximum voluntary contraction (MVC) at the same fascicle length, rather than the joint angle, adopted during training. Sixteen healthy women (21.8 ± 1.5 years) were randomly divided into an intervention group and a control group. Before (Pre) and after (Post) training, isometric plantarflexion MVCs were measured every 10° through the range of ankle joint position from 20° dorsiflexion to 30° plantarflexion (i.e., 6 ankle angles). Medial gastrocnemius fascicle length was also measured at each position, using B-mode ultrasound under 3 conditions of muscle activation: at rest, 30%MVC at respective angles, and MVC. Plantarflexion resistance training at an angle of 20° plantarflexion was performed 3 days a week for 4 weeks at 30%MVC using 3 sets of twenty 3-second isometric contractions. Maximum voluntary contraction in the intervention group increased at 0 and 10° plantarflexion (0°; Pre: 81.2 ± 26.5 N·m, Post: 105.0 ± 21.6 N·m, 10°; Pre: 63.0 ± 23.6 N·m, Post: 81.3 ± 20.3 N·m), which was not the angle used in training (20°). However, the fascicle length adopted in training at 20° plantarflexion and 30%MVC was similar to the value at 0 or 10° plantarflexion at MVC. Low-intensity isometric training at a shortened muscle length may be effective for improving MVC at a lengthened muscle length because of specificity of the fascicle length than the joint angle.

  9. Reliable Selection of the Number of Fascicles in Diffusion Images by Estimation of the Generalization Error

    PubMed Central

    Scherrer, Benoit; Taquet, Maxime; Warfield, Simon K.

    2014-01-01

    A number of diffusion models have been proposed to overcome the limitations of diffusion tensor imaging (DTI) which cannot represent multiple fascicles with heterogeneous orientations at each voxel. Among them, generative models such as multi-tensor models, CHARMED or NODDI represent each fascicle with a parametric model and are of great interest to characterize and compare white matter properties. However, the identification of the appropriate model, and particularly the estimation of the number of fascicles, has proven challenging. In this context, different model selection approaches have been proposed to identify the number of fascicles at each voxel. Most approaches attempt to maximize the quality of fit while penalizing complex models to avoid overfitting. However, the choice of a penalization strategy and the trade-off between penalization and quality of fit are rather arbitrary and produce highly variable results. In this paper, we propose for the first time to determine the number of fascicles at each voxel by assessing the generalization error. This criterion naturally prevents overfitting by comparing how the models predict new data not included in the model estimation. Since the generalization error cannot be directly computed, we propose to estimate it by the 632 bootstrap technique which has low bias and low variance. Results on synthetic phantoms and in vivo data show that our approach performs better than existing techniques, and is robust to the choice of decision threshold. Together with generative models of the diffusion signal, this technique will enable accurate identification of the model complexity at each voxel and accurate assessment of the white matter characteristics. PMID:24684014

  10. Effects of Growth on Muscle, Tendon, and Aponeurosis Tissues in Rabbit Shank Musculature.

    PubMed

    Böl, Markus; Leichsenring, Kay; Siebert, Tobias

    2016-12-20

    There exist several studies using morphological analyses of skeletal muscles to obtain a better understanding of muscle structure. The structural information obtained are primarily determined from single muscle components using individual animals of discrete ages. Further, little is known about changing dimensions of the aponeurosis, which is an important load-transferring interface in muscle mechanics. Thus, the aim of the present study was to determine how the muscle, tendon, and particularly the aponeurosis geometry of the rabbit shank musculature (M. soleus, M. extensor digitorum longus, and M. plantaris) change during growth. In doing so, morphological studies on muscles of eighty-nine female rabbits aged between 18 and 108 days were conducted. We found an almost linear increase over time in all of the geometrical parameters observed. The aponeurosis of the muscles exhibited lower growth rates in width than in length. The distal and proximal aponeurosis areas were nearly identical. The ratio of aponeurosis area to the physiological cross-sectional area was 2.54, 2.54, and 1.88 for M. soleus, M. extensor digitorum longus, and M. plantaris, respectively. M. extensor digitorum longus and M. soleus exhibited a nearly similar tendon-muscle fascicle length ratio during growth, increasing from 2.86 to 5.30 and 3.48 to 6.16, respectively. Interestingly, the tendon-muscle fascicle length ratio of the M. plantaris started initially with a much higher value (∼8) and increased to ∼18. Taken together, these results provide insight into the structure of the muscle-tendon complex and thus, a general understanding of muscle growth. Anat Rec, 2016. © 2016 Wiley Periodicals, Inc.

  11. Reconstruction of muscle fascicle architecture from iodine-enhanced microCT images: A combined texture mapping and streamline approach.

    PubMed

    Kupczik, Kornelius; Stark, Heiko; Mundry, Roger; Neininger, Fabian T; Heidlauf, Thomas; Röhrle, Oliver

    2015-10-07

    Skeletal muscle models are used to investigate motion and force generation in both biological and bioengineering research. Yet, they often lack a realistic representation of the muscle's internal architecture which is primarily composed of muscle fibre bundles, known as fascicles. Recently, it has been shown that fascicles can be resolved with micro-computed tomography (µCT) following staining of the muscle tissue with iodine potassium iodide (I2KI). Here, we present the reconstruction of the fascicular spatial arrangement and geometry of the superficial masseter muscle of a dog based on a combination of pattern recognition and streamline computation. A cadaveric head of a dog was incubated in I2KI and µCT-scanned. Following segmentation of the masseter muscle a statistical pattern recognition algorithm was applied to create a vector field of fascicle directions. Streamlines were then used to transform the vector field into a realistic muscle fascicle representation. The lengths of the reconstructed fascicles and the pennation angles in two planes (frontal and sagittal) were extracted and compared against a tracked fascicle field obtained through cadaver dissection. Both fascicle lengths and angles were found to vary substantially within the muscle confirming the complex and heterogeneous nature of skeletal muscle described by previous studies. While there were significant differences in the pennation angle between the experimentally derived and µCT-reconstructed data, there was congruence in the fascicle lengths. We conclude that the presented approach allows for embedding realistic fascicle information into finite element models of skeletal muscles to better understand the functioning of the musculoskeletal system.

  12. Tendon transfer or tendon graft for ruptured finger extensor tendons in rheumatoid hands.

    PubMed

    Chung, U S; Kim, J H; Seo, W S; Lee, K H

    2010-05-01

    We evaluated the clinical outcome of tendon reconstruction using tendon graft or tendon transfer and the parameters related to clinical outcome in 51 wrists of 46 patients with rheumatoid arthritis with finger extensor tendon ruptures. At a mean follow-up of 5.6 years, the mean metacarpophalangeal (MP) joint extension lag was 8 degrees (range, 0-45) and the mean visual analogue satisfaction scale was 74 (range, 10-100). Clinical outcome did not differ significantly between tendon grafting and tendon transfer. The MP joint extension lag correlated with the patient's satisfaction score, but the pulp-to-palm distance did not correlate with patient satisfaction. We conclude that both tendon grafting and tendon transfer are reliable reconstruction methods for ruptured finger extensor tendons in rheumatoid hands.

  13. Continuous Shear Wave Elastography: a New Method to Measure in-vivo Viscoelastic Properties of Tendons

    PubMed Central

    Cortes, Daniel H.; Suydam, Stephen M.; Silbernagel, Karin Grävare; Buchanan, Thomas S.; Elliott, Dawn M.

    2015-01-01

    Viscoelastic mechanical properties are frequently altered after tendon injuries and during recovery. Therefore, non-invasive measurements of shear viscoelastic properties may help evaluate tendon recovery and compare the effectiveness of different therapies. The objectives of this study are to present an elastography method to measure localized viscoelastic properties of tendon and to present initial results in healthy and injured human Achilles and semitendinosus tendons. The technique used an external actuator to generate the shear waves in the tendon at different frequencies and plane wave imaging to measure shear wave displacements. For each of the excitation frequencies, maps of direction specific wave speeds were calculated using Local Frequency Estimation. Maps of viscoelastic properties were obtained using a pixel wise curve-fit of wave speed and frequency. The method was validated by comparing measurements of wave speed in agarose gels to those obtained using magnetic resonance elastography. Measurements in human healthy Achilles tendons revealed a pronounced increase in wave speed as function of frequency that highlights the importance of tendon viscoelasticity. Additionally, the viscoelastic properties of the Achilles tendon were larger than those reported for other tissues. Measurements in a tendinopathic Achilles tendon showed that it is feasible to quantify local viscoeasltic properties. Similarly, measurement in the semitendinosus tendon showed a substantial differences in viscoelastic properties between the healthy and contralateral tendons. Consequently, this technique has the potential of evaluating localized changes in tendon viscoelastic properties due to injury and during recovery in a clinical setting. PMID:25796414

  14. Regulation of tendon differentiation by scleraxis distinguishes force-transmitting tendons from muscle-anchoring tendons.

    PubMed

    Murchison, Nicholas D; Price, Brian A; Conner, David A; Keene, Douglas R; Olson, Eric N; Tabin, Clifford J; Schweitzer, Ronen

    2007-07-01

    The scleraxis (Scx) gene, encoding a bHLH transcription factor, is expressed in the progenitors and cells of all tendon tissues. To determine Scx function, we produced a mutant null allele. Scx-/- mice were viable, but showed severe tendon defects, which manifested in a drastically limited use of all paws and back muscles and a complete inability to move the tail. Interestingly, although the differentiation of all force-transmitting and intermuscular tendons was disrupted, other categories of tendons, the function of which is mainly to anchor muscles to the skeleton, were less affected and remained functional, enabling the viability of Scx-/- mutants. The force-transmitting tendons of the limbs and tail varied in the severity to which they were affected, ranging from dramatic failure of progenitor differentiation resulting in the loss of segments or complete tendons, to the formation of small and poorly organized tendons. Tendon progenitors appeared normal in Scx-/- embryos and a phenotype resulting from a failure in the condensation of tendon progenitors to give rise to distinct tendons was first detected at embryonic day (E)13.5. In the tendons that persisted in Scx-/- mutants, we found a reduced and less organized tendon matrix and disorganization at the cellular level that led to intermixing of tenocytes and endotenon cells. The phenotype of Scx-/- mutants emphasizes the diversity of tendon tissues and represents the first molecular insight into the important process of tendon differentiation.

  15. The influence of loading intensity on muscle-tendon unit behavior during maximal knee extensor stretch shortening cycle exercise.

    PubMed

    Earp, Jacob E; Newton, Robert U; Cormie, Prue; Blazevich, Anthony J

    2014-01-01

    Tendon stiffness increases as the magnitude and rate of loading increases, according to its viscoelastic properties. Thus, under some loading conditions tendons should become exceptionally stiff and act almost as rigid force transducers. Nonetheless, observations of tendon behavior during multi-joint sprinting and jumping tasks have shown that tendon strain increases whilst muscle strain decreases as the loading intensity increases. The purpose of the current study was to examine the influence of external loading intensity on muscle-tendon unit (MTU) behavior during a high-speed single-joint, stretch-shortening cycle (SSC) knee extension task. Eighteen men (n = 9) and women (n = 9) performed single-leg, maximum intensity SSC knee extensions at loads of 20, 60 and 90% of their one repetition maximum. Vastus lateralis fascicle length (L(f)) and velocity (v(f)) as well as MTU (L(MTU)) and tendinous tissue (L(t)) length were measured using high-speed ultrasonography (96 Hz). Patellar tendon force (F(t)) and rate of force development (RFDt) were estimated using inverse dynamics. Results showed that as loading intensity increased, concentric joint velocity and shortening v f decreased whilst F t and RFDt increased, but no significant differences were observed in eccentric joint velocity or peak L(MTU) or L(f). In addition, the tendon lengthened significantly less at the end of the eccentric phase at heavier loads. This is the first observation that tendon strain decreases significantly during a SSC movement as loading intensity increases in vivo, resulting in a shift in the tendon acting as a power amplifier at light loads to a more rigid force transducer at heavy loads.

  16. Complete Achilles tendon ruptures.

    PubMed

    Landvater, S J; Renström, P A

    1992-10-01

    Achilles tendon ruptures can be treated nonsurgically in the nonathletic or low-end recreational athletic patient, particularly those more than 50 years of age, provided the treating physician does not delay in the diagnosis and treatment (preferably less than 48 hrs and possibly less than 1 week). The patient should be advised of the higher incidence of re-rupture of the tendon when treated nonsurgically. Surgical treatment is recommended for patients who are young and athletic. This is particularly true because the major criticism of surgical treatment has been the complication rate, which has decreased to a low level and to a mild degree, usually not significantly affecting the repair over time. Surgical treatment in these individuals seems to be superior not only in regard to re-rupture but also in assuring the correct apposition of the tendon ends and in placing the necessary tension on the tendon to secure appropriate orientation of the collagen fibers. This in turn allows them to regain full strength, power, endurance, and an early return to sports. Surgery is also recommended for late diagnosed ruptures where there is significant lengthening of the tendon. Surgical technique should involve a medial incision to avoid the sural nerve, absorbable suture, and augmentation with fascia or tendon where there is a gap or late rupture. Postoperatively, the immobilization should be 7 to 10 days in a splint. A walking boot with early motion in plantar flexion or a short leg cast with the tendon under slight tension should thereafter be used for 4 to 5 weeks. An early and well-supervised rehabilitation program should be initiated to restore the patient to the preinjury activity level.

  17. Intra- and intermuscular variation in human quadriceps femoris architecture assessed in vivo

    PubMed Central

    Blazevich, Anthony J; Gill, Nicholas D; Zhou, Shi

    2006-01-01

    Despite the functional importance of the human quadriceps femoris in movements such as running, jumping, lifting and climbing, and the known effects of muscle architecture on muscle function, no research has fully described the complex architecture of this muscle group. We used ultrasound imaging techniques to measure muscle thickness, fascicle angle and fascicle length at multiple regions of the four quadriceps muscles in vivo in 31 recreationally active, but non-strength-trained adult men and women. Our analyses revealed a reasonable similarity in the superficial quadriceps muscles, which is suggestive of functional similarity (at least during the uni-joint knee extension task) given that they act via a common tendon. The deep vastus intermedius (VI) is architecturally dissimilar and therefore probably serves a different function(s). Architecture varies significantly along the length of the superficial muscles, which has implications for the accuracy of models that assume a constant intramuscular architecture. It might also have consequences for the efficiency of intra- and intermuscular force transmission. Our results provide some evidence that subjects with a given architecture of one superficial muscle, relative to the rest of the subject sample, also have a similar architecture in other superficial muscles. However, this is not necessarily true for vastus lateralis (VL), and was not the case for VI. Therefore, the relative architecture of one muscle cannot confidently be used to estimate the relative architecture of another. To confirm this, we calculated a value of whole quadriceps architecture by four different methods. Regardless of the method used, we found that the absolute or relative architecture of one muscle could not be used as an indicator of whole quadriceps architecture, although vastus medialis, possibly in concert with VL and the anterior portion of VI, could be used to provide a useful snapshot. Importantly, our estimates of whole quadriceps

  18. Biodegradable synthetic scaffolds for tendon regeneration

    PubMed Central

    Reverchon, Ernesto; Baldino, Lucia; Cardea, Stefano; De Marco, Iolanda

    2012-01-01

    Summary Tissue regeneration is aimed at producing biological or synthetic scaffolds to be implanted in the body for regenerate functional tissues. Several techniques and materials have been used to obtain biodegradable synthetic scaffolds, on which adhesion, growth, migration and differentiation of human cells has been attempted. Scaffolds for tendon regeneration have been less frequently proposed, because they have a complex hierarchical structure and it is very difficult to mimic their peculiar mechanical properties. In this review, we critically analyzed the proposed materials and fabrication techniques for tendon tissue engineering and we indicated new preparation processes, based on the use of supercritical fluids, to produce scaffolds with characteristics very similar to the native tendon structure. PMID:23738295

  19. Steroid injections - tendon, bursa, joint

    MedlinePlus

    ... ency/article/007678.htm Steroid injections - tendon, bursa, joint To use the sharing features on this page, ... often painful. It can be injected into a joint, tendon, or bursa. Description Your health care provider ...

  20. Tendon Driven Finger Actuation System

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Reich, David M. (Inventor); Bridgwater, Lyndon (Inventor); Linn, Douglas Martin (Inventor); Askew, Scott R. (Inventor); Diftler, Myron A. (Inventor); Platt, Robert (Inventor); Hargrave, Brian (Inventor); Valvo, Michael C. (Inventor); Abdallah, Muhammad E. (Inventor); Permenter, Frank Noble (Inventor); Mehling, Joshua S. (Inventor)

    2013-01-01

    A humanoid robot includes a robotic hand having at least one finger. An actuation system for the robotic finger includes an actuator assembly which is supported by the robot and is spaced apart from the finger. A tendon extends from the actuator assembly to the at least one finger and ends in a tendon terminator. The actuator assembly is operable to actuate the tendon to move the tendon terminator and, thus, the finger.

  1. Depth-dependent variations in Achilles tendon deformations with age are associated with reduced plantarflexor performance during walking.

    PubMed

    Franz, Jason R; Thelen, Darryl G

    2015-08-01

    The anatomical arrangement of the Achilles tendon (AT), with distinct fascicle bundles arising from the gastrocnemius and soleus muscles, may facilitate relatively independent behavior of the triceps surae muscles. A reduced capacity for sliding between adjacent tendon fascicles with age may couple gastrocnemius and soleus muscle behavior, thereby potentially contributing to diminished plantarflexor performance commonly observed in old adults. Nine healthy young (mean age, 23.9 yr) and eight healthy old (69.9 yr) adults walked at three speeds (0.75, 1.00, and 1.25 m/s) on a force-sensing treadmill. We coupled dynamic ultrasound imaging of the free AT with motion capture and inverse dynamic analyses to compute, in part: 1) depth-dependent variations in AT tissue displacements and elongations and 2) net ankle joint kinetics during push-off. The difference in displacements between superficial and deep AT regions, and in their corresponding elongations, did not differ between old and young adults at the slower two walking speeds (P > 0.61). However, old adults walked with 41% smaller depth-dependent variations in free AT displacements and elongations at 1.25 m/s (P = 0.02). These more uniform tendon deformations in old adults most strongly correlated with reduced peak ankle moment (R(2) = 0.40), but also significantly correlated with reduced peak power generation (R(2) = 0.15) and positive ankle work during push-off (R(2) = 0.19) (P > 0.01). Our findings: 1) demonstrate a potential role for nonuniform AT deformations in governing gastrocnemius and soleus muscle-tendon function and 2) allude to altered tendon behavior that may contribute to the age-related reduction in plantarflexor performance during walking.

  2. Neuronal regulation of tendon homoeostasis.

    PubMed

    Ackermann, Paul W

    2013-08-01

    The regulation of tendon homoeostasis, including adaptation to loading, is still not fully understood. Accumulating data, however, demonstrates that in addition to afferent (sensory) functions, the nervous system, via efferent pathways which are associated with through specific neuronal mediators plays an active role in regulating pain, inflammation and tendon homeostasis. This neuronal regulation of intact-, healing- and tendinopathic tendons has been shown to be mediated by three major groups of molecules including opioid, autonomic and excitatory glutamatergic neuroregulators. In intact healthy tendons the neuromediators are found in the surrounding structures: paratenon, endotenon and epitenon, whereas the proper tendon itself is practically devoid of neurovascular supply. This neuroanatomy reflects that normal tendon homoeostasis is regulated from the tendon surroundings. After injury and during tendon repair, however, there is extensive nerve ingrowth into the tendon proper, followed by a time-dependent emergence of sensory, autonomic and glutamatergic mediators, which amplify and fine-tune inflammation and regulate tendon regeneration. In tendinopathic condition, excessive and protracted presence of sensory and glutamatergic neuromediators has been identified, suggesting involvement in inflammatory, nociceptive and hypertrophic (degenerative) tissue responses. Under experimental and clinical conditions of impaired (e.g. diabetes) as well as excessive (e.g. tendinopathy) neuromediator release, dysfunctional tendon homoeostasis develops resulting in chronic pain and gradual degeneration. Thus there is a prospect that in the future pharmacotherapy and tissue engineering approaches targeting neuronal mediators and their receptors may prove to be effective therapies for painful, degenerative and traumatic tendon disorders.

  3. Neuronal regulation of tendon homoeostasis

    PubMed Central

    Ackermann, Paul W

    2013-01-01

    The regulation of tendon homoeostasis, including adaptation to loading, is still not fully understood. Accumulating data, however, demonstrates that in addition to afferent (sensory) functions, the nervous system, via efferent pathways which are associated with through specific neuronal mediators plays an active role in regulating pain, inflammation and tendon homeostasis. This neuronal regulation of intact-, healing- and tendinopathic tendons has been shown to be mediated by three major groups of molecules including opioid, autonomic and excitatory glutamatergic neuroregulators. In intact healthy tendons the neuromediators are found in the surrounding structures: paratenon, endotenon and epitenon, whereas the proper tendon itself is practically devoid of neurovascular supply. This neuroanatomy reflects that normal tendon homoeostasis is regulated from the tendon surroundings. After injury and during tendon repair, however, there is extensive nerve ingrowth into the tendon proper, followed by a time-dependent emergence of sensory, autonomic and glutamatergic mediators, which amplify and fine-tune inflammation and regulate tendon regeneration. In tendinopathic condition, excessive and protracted presence of sensory and glutamatergic neuromediators has been identified, suggesting involvement in inflammatory, nociceptive and hypertrophic (degenerative) tissue responses. Under experimental and clinical conditions of impaired (e.g. diabetes) as well as excessive (e.g. tendinopathy) neuromediator release, dysfunctional tendon homoeostasis develops resulting in chronic pain and gradual degeneration. Thus there is a prospect that in the future pharmacotherapy and tissue engineering approaches targeting neuronal mediators and their receptors may prove to be effective therapies for painful, degenerative and traumatic tendon disorders. PMID:23718724

  4. Tendon extracellular matrix damage, degradation and inflammation in response to in vitro overload exercise.

    PubMed

    Spiesz, Ewa M; Thorpe, Chavaunne T; Chaudhry, Saira; Riley, Graham P; Birch, Helen L; Clegg, Peter D; Screen, Hazel R C

    2015-06-01

    The role of inflammation in tendon injury is uncertain and a topic of current interest. In vitro studies of tendon accelerated overload damage can serve as a valuable source of information on the early stages of tendinopathy. Viable fascicle bundles from bovine flexor tendons were subjected to cyclic uniaxial loading from 1-10% strain. Immuno-staining for inflammatory markers and matrix degradation markers was performed on the samples after mechanical testing. Loaded samples exhibited visible extracellular matrix damage, with disrupted collagen fibers and fiber kinks, and notable damage to the interfascicular matrix. Inflammatory markers COX-2 and IL-6 were only expressed in the cyclically loaded samples. Collagen degradation markers MMP-1 and C1,2C were colocalized in many areas, with staining occurring in the interfascicular matrix or the fascicular tenocytes. These markers were present in control samples, but staining became increasingly intense with loading. Little MMP-3 or MMP-13 was evident in control sections. In loaded samples, some sections showed intense staining of these markers, again localized to interfascicular regions. This study suggests that inflammatory markers may be expressed rapidly after tendon overload exercise. Interestingly, both inflammation and damage-induced matrix remodeling seem to be concentrated in, or in the vicinity of, the highly cellular interfascicular matrix.

  5. Quantitative ultrasound method for assessing stress-strain properties and the cross-sectional area of Achilles tendon

    NASA Astrophysics Data System (ADS)

    Du, Yi-Chun; Chen, Yung-Fu; Li, Chien-Ming; Lin, Chia-Hung; Yang, Chia-En; Wu, Jian-Xing; Chen, Tainsong

    2013-12-01

    The Achilles tendon is one of the most commonly observed tendons injured with a variety of causes, such as trauma, overuse and degeneration, in the human body. Rupture and tendinosis are relatively common for this strong tendon. Stress-strain properties and shape change are important biomechanical properties of the tendon to assess surgical repair or healing progress. Currently, there are rather limited non-invasive methods available for precisely quantifying the in vivo biomechanical properties of the tendons. The aim of this study was to apply quantitative ultrasound (QUS) methods, including ultrasonic attenuation and speed of sound (SOS), to investigate porcine tendons in different stress-strain conditions. In order to find a reliable method to evaluate the change of tendon shape, ultrasound measurement was also utilized for measuring tendon thickness and compared with the change in tendon cross-sectional area under different stress. A total of 15 porcine tendons of hind trotters were examined. The test results show that the attenuation and broadband ultrasound attenuation decreased and the SOS increased by a smaller magnitude as the uniaxial loading of the stress-strain upon tendons increased. Furthermore, the tendon thickness measured with the ultrasound method was significantly correlated with tendon cross-sectional area (Pearson coefficient = 0.86). These results also indicate that attenuation of QUS and ultrasonic thickness measurement are reliable and potential parameters for assessing biomechanical properties of tendons. Further investigations are needed to warrant the application of the proposed method in a clinical setting.

  6. Spatial arrangement of the heart muscle fascicles and intramyocardial connective tissue in the Spanish fighting bull (Bos taurus).

    PubMed Central

    Sánchez-Quintana, D; Climent, V; Garcia-Martinez, V; Rojo, M; Hurlé, J M

    1994-01-01

    The spatial arrangement of the muscle fascicles and intramyocardial connective tissue was examined in the ventricles of the heart of the Spanish fighting bull (Bos taurus). In both ventricles, the muscle fascicles of the myocardium are arranged in 3 main directions, forming 3 muscle layers within the ventricular wall. The preferentially vertical arrangement of the muscle fascicles in the superficial and deep layers at the level of the fibrous aortic rings and the base of the semilunar valve leaflets suggests that these fascicles are actively involved in valvular dynamics. After controlled digestion of myocytes and elastic fibres with NaOH, a 3-dimensional arrangement of the scaffolding of connective tissue that supports the muscle fascicles and myocytes was observed. The arrangement and structure of this scaffolding may influence the order of contraction of muscle fascicles in different layers of the ventricle. In addition, differences were observed between the connective tissue scaffolding surrounding the myocytes of the 2 ventricles; these variations were correlated with the different biomechanical properties. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 8 Fig. 9 Fig. 10 PMID:8014119

  7. US imaging in operated tendons.

    PubMed

    Cohen, M

    2012-02-01

    Ultrasound (US) plays an essential role in the follow-up of operated tendons. The US operator must keep in mind three main elements: healing of traumatic injuries of the tendons seems to follow the biological model of histologic healing, surgical repair of a tendon rupture improves the structural parameters of the operated tendon, but it does not grant restitutio ad integrum, and US findings therefore seem poorly correlated with the functional evolution.Before examination, the US operator should be familiar with the nature of the tendon injury that has led to surgery including location, severity, time elapsed between tendon injury and surgical repair, surgical technique, postoperative course and possible complications. US findings in operated as well as non-operated tendons depend on several factors: morphology, structure, vascularization of the tendon, mobility of the tendon and mobility of the peritendinous tissues. Particular features are therefore considered according to the location: shoulder, elbow, wrist, hand, knee, ankle and foot. Interpretation of the US image requires knowledge of the surgical technique and "normal" postoperative appearance of the operated tendon in order to detect pathological findings such as thinning, persistent fluid collections within or around the tendon, persistent hypervascularization, intratendinous calcifications and adhesions.

  8. Subject-specific finite element analysis to characterize the influence of geometry and material properties in Achilles tendon rupture.

    PubMed

    Shim, Vickie B; Fernandez, Justin W; Gamage, Prasad B; Regnery, Camille; Smith, David W; Gardiner, Bruce S; Lloyd, David G; Besier, Thor F

    2014-11-28

    Achilles tendon injuries including rupture are one of the most frequent musculoskeletal injuries, but the mechanisms for these injuries are still not fully understood. Previous in vivo and experimental studies suggest that tendon rupture mainly occurs in the tendon mid-section and predominantly more in men than women due to reasons yet to be identified. Therefore we aimed to investigate possible mechanisms for tendon rupture using finite element (FE) analysis. Specifically, we have developed a framework for generating subject-specific FE models of human Achilles tendon. A total of ten 3D FE models of human Achilles tendon were generated. Subject-specific geometries were obtained using ultrasound images and a mesh morphing technique called Free Form Deformation. Tendon material properties were obtained by performing material optimization that compared and minimized difference in uniaxial tension experimental results with model predictions. Our results showed that both tendon geometry and material properties are highly subject-specific. This subject-specificity was also evident in our rupture predictions as the locations and loads of tendon ruptures were different in all specimens tested. A parametric study was performed to characterize the influence of geometries and material properties on tendon rupture. Our results showed that tendon rupture locations were dependent largely on geometry while rupture loads were more influenced by tendon material properties. Future work will investigate the role of microstructural properties of the tissue on tendon rupture and degeneration by using advanced material descriptions.

  9. Advanced glycation end-products diminish tendon collagen fiber sliding.

    PubMed

    Li, Yufei; Fessel, Gion; Georgiadis, Marios; Snedeker, Jess G

    2013-04-24

    Connective tissue aging and diabetes related comorbidity are associated with compromised tissue function, increased susceptibility to injury, and reduced healing capacity. This has been partly attributed to collagen cross-linking by advanced glycation end-products (AGEs) that accumulate with both age and disease. While such cross-links are believed to alter the physical properties of collagen structures and tissue behavior, existing data relating AGEs to tendon mechanics is contradictory. In this study, we utilized a rat tail tendon model to quantify the micro-mechanical repercussion of AGEs at the collagen fiber-level. Individual tendon fascicles were incubated with methylglyoxal (MGO), a naturally occurring metabolite known to form AGEs. After incubation in MGO solution or buffer only, tendons were stretched on the stage of a multiphoton confocal microscope and individual collagen fiber stretch and relative fiber sliding were quantified. Treatment by MGO yielded increased fluorescence and elevated denaturation temperatures as found in normally aged tissue, confirming formation of AGEs and related cross-links. No apparent ultrastructural changes were noted in transmission electron micrographs of cross-linked fibrils. MGO treatment strongly reduced tissue stress relaxation (p<0.01), with concomitantly increased tissue yield stress (p<0.01) and ultimate failure stress (p=0.036). MGO did not affect tangential modulus in the linear part of the stress-strain curve (p=0.46). Microscopic analysis of collagen fiber kinematics yielded striking results, with MGO treatment drastically reducing fiber-sliding (p<0.01) with a compensatory increase in fiber-stretch (p<0.01). We thus conclude that the main mechanical effect of AGEs is a loss of tissue viscoelasticity driven by matrix-level loss of fiber-fiber sliding. This has potentially important implications to tissue damage accumulation, mechanically regulated cell signaling, and matrix remodeling. It further highlights the

  10. Tendon injuries of the hand

    PubMed Central

    Schöffl, Volker; Heid, Andreas; Küpper, Thomas

    2012-01-01

    Tendon injuries are the second most common injuries of the hand and therefore an important topic in trauma and orthopedic patients. Most injuries are open injuries to the flexor or extensor tendons, but less frequent injuries, e.g., damage to the functional system tendon sheath and pulley or dull avulsions, also need to be considered. After clinical examination, ultrasound and magnetic resonance imaging have proved to be important diagnostic tools. Tendon injuries mostly require surgical repair, dull avulsions of the distal phalanges extensor tendon can receive conservative therapy. Injuries of the flexor tendon sheath or single pulley injuries are treated conservatively and multiple pulley injuries receive surgical repair. In the postoperative course of flexor tendon injuries, the principle of early passive movement is important to trigger an “intrinsic” tendon healing to guarantee a good outcome. Many substances were evaluated to see if they improved tendon healing; however, little evidence was found. Nevertheless, hyaluronic acid may improve intrinsic tendon healing. PMID:22720265

  11. Spontaneous Iliopsoas Tendon Tear

    PubMed Central

    Rodriguez, Mary; Patnaik, Soumya; Wang, Peter

    2016-01-01

    Hip pain is one of the most common reasons for the elderly to present to the emergency department, and the differential diagnosis spectrum is vast. Iliopsoas injury is a relatively uncommon condition that may present with hip or groin pain. It is usually seen in athletes due to trauma, particularly flexion injuries. However, spontaneous iliopsoas tendon tear is extremely rare, and only a small number of cases have been reported; it has an estimated prevalence of 0.66% in individuals from 7 to 95 years. Risk factors include aging, use of steroids, and chronic diseases. Magnetic resonance imaging (MRI) using its high soft-tissue contrast resolution remains the most valuable imaging modality. A prompt diagnosis and treatment, which is usually conservative, is important to improve the quality of life in this group of patients. We describe a case of spontaneous iliopsoas tendon tear in an elderly woman. PMID:26929854

  12. Scaffolds in Tendon Tissue Engineering

    PubMed Central

    Longo, Umile Giuseppe; Lamberti, Alfredo; Petrillo, Stefano; Maffulli, Nicola; Denaro, Vincenzo

    2012-01-01

    Tissue engineering techniques using novel scaffold materials offer potential alternatives for managing tendon disorders. Tissue engineering strategies to improve tendon repair healing include the use of scaffolds, growth factors, cell seeding, or a combination of these approaches. Scaffolds have been the most common strategy investigated to date. Available scaffolds for tendon repair include both biological scaffolds, obtained from mammalian tissues, and synthetic scaffolds, manufactured from chemical compounds. Preliminary studies support the idea that scaffolds can provide an alternative for tendon augmentation with an enormous therapeutic potential. However, available data are lacking to allow definitive conclusion on the use of scaffolds for tendon augmentation. We review the current basic science and clinical understanding in the field of scaffolds and tissue engineering for tendon repair. PMID:22190961

  13. Soleus fascicle length changes are conserved between young and old adults at their preferred walking speed.

    PubMed

    Panizzolo, Fausto A; Green, Daniel J; Lloyd, David G; Maiorana, Andrew J; Rubenson, Jonas

    2013-09-01

    Older adults have been shown to naturally select a walking speed approximately 20% slower than younger adults. We explored the possibility that a reduction in preferred speed in older adults represents a strategy to preserve the mechanical function of the leg muscles. We examined this question in the soleus muscle in eight healthy young (25.8±3.5 years) and eight healthy older adults (66.1±2.3 years) who were paired so that their preferred speed differed by ∼20%. Soleus muscle fascicle lengths were recorded dynamically using ultrasound, together with simultaneous measurements of soleus EMG activity and ankle joint kinematics while (a) older adults walked on a treadmill at a speed 20% above their preferred speed (speeds matched to the preferred speed of young adults), and (b) young and older adults walked at their preferred treadmill speeds. Analyses of mean muscle fascicle length changes revealed that, at matched speeds, older adults had a statistically different soleus fascicle length pattern compared to young adults, where the muscle's stretch-shorten cycle during stance was diminished. However, older adults walking at their preferred speed exhibited a more pronounced stretch-shorten cycle that was not statistically different from young adults. Conserving muscle length patterns through a reduction in speed in older adults may represent a physiologically relevant modulation of muscle function that permits greater force and power production. Our findings offer a novel mechanical explanation for the slower walking speed in older adults, whereby a reduction in speed may permit muscles to function in a mechanically similar manner to that of younger adults.

  14. Comparative analysis of transverse intrafascicular multichannel, longitudinal intrafascicular and multipolar cuff electrodes for the selective stimulation of nerve fascicles

    NASA Astrophysics Data System (ADS)

    Badia, Jordi; Boretius, Tim; Andreu, David; Azevedo-Coste, Christine; Stieglitz, Thomas; Navarro, Xavier

    2011-06-01

    The selection of a suitable nerve electrode for neuroprosthetic applications implies a trade-off between invasiveness and selectivity, wherein the ultimate goal is achieving the highest selectivity for a high number of nerve fascicles by the least invasiveness and potential damage to the nerve. The transverse intrafascicular multichannel electrode (TIME) is intended to be transversally inserted into the peripheral nerve and to be useful to selectively activate subsets of axons in different fascicles within the same nerve. We present a comparative study of TIME, LIFE and multipolar cuff electrodes for the selective stimulation of small nerves. The electrodes were implanted on the rat sciatic nerve, and the activation of gastrocnemius, plantar and tibialis anterior muscles was recorded by EMG signals. Thus, the study allowed us to ascertain the selectivity of stimulation at the interfascicular and also at the intrafascicular level. The results of this study indicate that (1) intrafascicular electrodes (LIFE and TIME) provide excitation circumscribed to the implanted fascicle, whereas extraneural electrodes (cuffs) predominantly excite nerve fascicles located superficially; (2) the minimum threshold for muscle activation with TIME and LIFE was significantly lower than with cuff electrodes; (3) TIME allowed us to selectively activate the three tested muscles when stimulating through different active sites of one device, both at inter- and intrafascicular levels, whereas selective activation using multipolar cuff (with a longitudinal tripolar stimulation configuration) was only possible for two muscles, at the interfascicular level, and LIFE did not activate selectively more than one muscle in the implanted nerve fascicle.

  15. Transverse Strains in Muscle Fascicles during Voluntary Contraction: A 2D Frequency Decomposition of B-Mode Ultrasound Images

    PubMed Central

    Wakeling, James M.

    2014-01-01

    When skeletal muscle fibres shorten, they must increase in their transverse dimensions in order to maintain a constant volume. In pennate muscle, this transverse expansion results in the fibres rotating to greater pennation angle, with a consequent reduction in their contractile velocity in a process known as gearing. Understanding the nature and extent of this transverse expansion is necessary to understand the mechanisms driving the changes in internal geometry of whole muscles during contraction. Current methodologies allow the fascicle lengths, orientations, and curvatures to be quantified, but not the transverse expansion. The purpose of this study was to develop and validate techniques for quantifying transverse strain in skeletal muscle fascicles during contraction from B-mode ultrasound images. Images were acquired from the medial and lateral gastrocnemii during cyclic contractions, enhanced using multiscale vessel enhancement filtering and the spatial frequencies resolved using 2D discrete Fourier transforms. The frequency information was resolved into the fascicle orientations that were validated against manually digitized values. The transverse fascicle strains were calculated from their wavelengths within the images. These methods showed that the transverse strain increases while the longitudinal fascicle length decreases; however, the extent of these strains was smaller than expected. PMID:25328509

  16. Achilles tendon injuries in athletes.

    PubMed

    Kvist, M

    1994-09-01

    Two-thirds of Achilles tendon injuries in competitive athletes are paratenonitis and one-fifth are insertional complaints (bursitis and insertion tendinitis). The remaining afflictions consist of pain syndromes of the myotendineal junction and tendinopathies. The majority of Achilles tendon injuries from sport occur in males, mainly because of their higher rates of participation in sport, but also with tendinopathies a gender difference is probably indicated. Athletes in running sports have a high incidence of Achilles tendon overuse injuries. About 75% of total and the majority of partial tendon ruptures are related to sports activities usually involving abrupt repetitive jumping and sprinting movements. Mechanical factors and a sedentary lifestyle play a role in the pathology of these injuries. Achilles tendon overuse injuries occur at a higher rate in older athletes than most other typical overuse injuries. Recreational athletes with a complete Achilles tendon rupture are about 15 years younger than those with other spontaneous tendon ruptures. Following surgery, about 70 to 90% of athletes have a successful comeback after Achilles tendon injury. Surgery is required in about 25% of athletes with Achilles tendon overuse injuries and the frequency of surgery increases with patient age and duration of symptoms as well as occurrence of tendinopathic changes. However, about 20% of injured athletes require a re-operation for Achilles tendon overuse injuries, and about 3 to 5% are compelled to abandon their sports career because of these injuries. Myotendineal junction pain should be treated conservatively. Partial Achilles tendon ruptures are primarily treated conservatively, although the best treatment method of chronic partial rupture seems to be surgery. Complete Achilles tendon ruptures of athletes are treated surgically, because this increases the likelihood of athletes reaching preinjury activity levels and minimises the risk of re-ruptures. Marked forefoot

  17. The Effect of Sodium Hyaluronate on Ligamentation and Biomechanical Property of Tendon in Repair of Achilles Tendon Defect with Polyethylene Terephthalate Artificial Ligament: A Rabbit Tendon Repair Model

    PubMed Central

    Li, Shengkun; Jiang, Jia; Chen, Shiyi

    2016-01-01

    The Achilles tendon is the most common ruptured tendon of human body. Reconstruction with polyethylene terephthalate (PET) artificial ligament is recommended in some serious cases. Sodium hyaluronate (HA) is beneficial for the healing of tendon injuries. We aimed to determine the effect of sodium hyaluronate in repair of Achilles tendon defect with PET artificial ligament in an animal tendon repair model. Sixteen New Zealand White rabbits were divided into two groups. Eight rabbits repaired with PET were assigned to PET group; the other eight rabbits repaired with PET along with injection of HE were assigned to HA-PET group. All rabbits were sacrificed at 4 and 8 weeks postoperatively for biomechanical and histological examination. The HA-PET group revealed higher biomechanical property compared with the PET group. Histologically, more collagen tissues grew into the HA-PET group compared with PET group. In conclusion, application of sodium hyaluronate can improve the healing of Achilles tendon reconstruction with polyethylene terephthalate artificial ligament. PMID:28105436

  18. Cellular therapy in bone-tendon interface regeneration

    PubMed Central

    Rothrauff, Benjamin B; Tuan, Rocky S

    2014-01-01

    The intrasynovial bone-tendon interface is a gradual transition from soft tissue to bone, with two intervening zones of uncalcified and calcified fibrocartilage. Following injury, the native anatomy is not restored, resulting in inferior mechanical properties and an increased risk of re-injury. Recent in vivo studies provide evidence of improved healing when surgical repair of the bone-tendon interface is augmented with cells capable of undergoing chondrogenesis. In particular, cellular therapy in bone-tendon healing can promote fibrocartilage formation and associated improvements in mechanical properties. Despite these promising results in animal models, cellular therapy in human patients remains largely unexplored. This review highlights the development and structure-function relationship of normal bone-tendon insertions. The natural healing response to injury is discussed, with subsequent review of recent research on cellular approaches for improved healing. Finally, opportunities for translating in vivo findings into clinical practice are identified. PMID:24326955

  19. Effects of acute static, ballistic, and PNF stretching exercise on the muscle and tendon tissue properties.

    PubMed

    Konrad, A; Stafilidis, S; Tilp, M

    2016-07-01

    The purpose of this study was to investigate the influence of a single static, ballistic, or proprioceptive neuromuscular facilitation (PNF) stretching exercise on the various muscle-tendon parameters of the lower leg and to detect possible differences in the effects between the methods. Volunteers (n = 122) were randomly divided into static, ballistic, and PNF stretching groups and a control group. Before and after the 4 × 30 s stretching intervention, we determined the maximum dorsiflexion range of motion (RoM) with the corresponding fascicle length and pennation angle of the gastrocnemius medialis. Passive resistive torque (PRT) and maximum voluntary contraction (MVC) were measured with a dynamometer. Observation of muscle-tendon junction (MTJ) displacement with ultrasound allowed us to determine the length changes in the tendon and muscle, respectively, and hence to calculate stiffness. Although RoM increased (static: +4.3%, ballistic: +4.5%, PNF: +3.5%), PRT (static: -11.4%, ballistic: -11.5%, PNF: -13,7%), muscle stiffness (static: -13.1%, ballistic: -20.3%, PNF: -20.2%), and muscle-tendon stiffness (static: -11.3%, ballistic: -10.5%, PNF: -13.7%) decreased significantly in all the stretching groups. Only in the PNF stretching group, the pennation angle in the stretched position (-4.2%) and plantar flexor MVC (-4.6%) decreased significantly. Multivariate analysis showed no clinically relevant difference between the stretching groups. The increase in RoM and the decrease in PRT and muscle-tendon stiffness could be explained by more compliant muscle tissue following a single static, ballistic, or PNF stretching exercise.

  20. Adaptive Remodeling of Achilles Tendon: A Multi-scale Computational Model

    PubMed Central

    Rubenson, Jonas; Umberger, Brian

    2016-01-01

    While it is known that musculotendon units adapt to their load environments, there is only a limited understanding of tendon adaptation in vivo. Here we develop a computational model of tendon remodeling based on the premise that mechanical damage and tenocyte-mediated tendon damage and repair processes modify the distribution of its collagen fiber lengths. We explain how these processes enable the tendon to geometrically adapt to its load conditions. Based on known biological processes, mechanical and strain-dependent proteolytic fiber damage are incorporated into our tendon model. Using a stochastic model of fiber repair, it is assumed that mechanically damaged fibers are repaired longer, whereas proteolytically damaged fibers are repaired shorter, relative to their pre-damage length. To study adaptation of tendon properties to applied load, our model musculotendon unit is a simplified three-component Hill-type model of the human Achilles-soleus unit. Our model results demonstrate that the geometric equilibrium state of the Achilles tendon can coincide with minimization of the total metabolic cost of muscle activation. The proposed tendon model independently predicts rates of collagen fiber turnover that are in general agreement with in vivo experimental measurements. While the computational model here only represents a first step in a new approach to understanding the complex process of tendon remodeling in vivo, given these findings, it appears likely that the proposed framework may itself provide a useful theoretical foundation for developing valuable qualitative and quantitative insights into tendon physiology and pathology. PMID:27684554

  1. Gliding resistance and modifications of gliding surface of tendon: clinical perspectives.

    PubMed

    Amadio, Peter C

    2013-05-01

    The smooth gliding of the normal human digital flexor is maintained by synovial fluid lubrication and lubricants bound to the tendon surface. This system can be disrupted by degenerative conditions such as trigger finger, or by trauma. The resistance to tendon gliding after surgical repair of the lacerated digital flexor tendon relates to location of suture knots, exposure of suture materials, and type of surgical repair and materials. Restoration of a functioning gliding surface after injury can be helped by using low-friction, high-strength suture designs, therapy that enables gliding, and the addition of lubricants to the tendon surface.

  2. Intramuscular architecture of the autochthonous back muscles in humans.

    PubMed

    Stark, Heiko; Fröber, Rosemarie; Schilling, Nadja

    2013-02-01

    Many training concepts take muscle properties such as contraction speed or muscle topography into account to achieve an optimal training outcome. Thus far, the internal architecture of muscles has largely been neglected, although it is well known that parameters such as pennation angles or the lengths of fascicles but also the proportions of fleshy and tendinous fascicle parts have a major impact on the contraction behaviour of a muscle. Here, we present the most detailed description of the intramuscular fascicle architecture of the human perivertebral muscles available so far. For this, one adult male cadaver was studied. Our general approach was to digitize the geometry of each fascicle of the muscles of back proper (Erector spinae) - the Spinalis thoracis, Iliocostalis lumborum, Longissimus thoracis and the Multifidus thoracis et lumborum - and of the deep muscles of the abdomen - Psoas minor, Psoas major and Quadratus lumborum - during a layerwise dissection. Architectural parameters such as fascicle angles to the sagittal and the frontal planes as well as fascicle lengths were determined for each fascicle, and are discussed regarding their consequences for the function of the muscle. For example, compared with the other dorsovertebral muscles, the Longissimus thoracis can produce greater shortening distances because of its relatively long fleshy portions, and it can store more elastic energy due to both its relatively long fleshy and tendinous fascicle portions. The Quadratus lumborum was outstanding because of its many architectural subunits defined by distinct attachment sites and fascicle lengths. The presented database will improve biomechanical models of the human trunk by allowing the incorporation of anisotropic muscle properties such as the fascicle direction into finite element models. This information will help to increase our understanding of the functionality of the human back musculature, and may thereby improve future training concepts.

  3. Achilles Tendon Rupture

    PubMed Central

    Wertz, Jess; Galli, Melissa; Borchers, James R.

    2013-01-01

    Context: Achilles tendon (AT) rupture in athletes is increasing in incidence and accounts for one of the most devastating sports injuries because of the threat to alter or end a career. Despite the magnitude of this injury, reliable risk assessment has not been clearly defined, and prevention strategies have been limited. The purpose of this review is to identify potential intrinsic and extrinsic risk factors for AT rupture in aerial and ground athletes stated in the current literature. Evidence Acquisition: A MEDLINE search was conducted on AT rupture, or “injury” and “risk factors” and “athletes” from 1980 to 2011. Emphasis was placed on epidemiology, etiology, and review articles focusing on the risk for lower extremity injury in runners and gymnasts. Thirty articles were reviewed, and 22 were included in this assessment. Results: Aerial and ground athletes share many intrinsic risk factors for AT rupture, including overuse and degeneration of the tendon as well as anatomical variations that mechanically put an athlete at risk. Older athletes, athletes atypical in size for their sport, high tensile loads, leg dominance, and fatigue also may increase risk. Aerial athletes tend to have more extrinsic factors that play a role in this injury due to the varying landing surfaces from heights and technical maneuvers performed at various skill levels. Conclusion: Risk assessment for AT rupture in aerial and ground athletes is multivariable and difficult in terms of developing prevention strategies. Quantitative measures of individual risk factors may help identify major contributors to injury. PMID:24427410

  4. Influence of acute and chronic streptozotocin-induced diabetes on the rat tendon extracellular matrix and mechanical properties.

    PubMed

    Volper, Brent D; Huynh, Richard T; Arthur, Kathryn A; Noone, Joshua; Gordon, Benjamin D; Zacherle, Emily W; Munoz, Eduardo; Sørensen, Mikkel A; Svensson, René B; Broderick, Tom L; Magnusson, S Peter; Howden, Reuben; Hale, Taben M; Carroll, Chad C

    2015-11-01

    Diabetes is a major risk factor for tendinopathy, and tendon abnormalities are common in diabetic patients. The purpose of the present study was to evaluate the effect of streptozotocin (60 mg/kg)-induced diabetes and insulin therapy on tendon mechanical and cellular properties. Sprague-Dawley rats (n = 40) were divided into the following four groups: nondiabetic (control), 1 wk of diabetes (acute), 10 wk of diabetes (chronic), and 10 wk of diabetes with insulin treatment (insulin). After 10 wk, Achilles tendon and tail fascicle mechanical properties were similar between groups (P > 0.05). Cell density in the Achilles tendon was greater in the chronic group compared with the control and acute groups (control group: 7.8 ± 0.5 cells/100 μm(2), acute group: 8.3 ± 0.4 cells/100 μm(2), chronic group: 10.9 ± 0.9 cells/100 μm(2), and insulin group: 9.2 ± 0.8 cells/100 μm(2), P < 0.05). The density of proliferating cells in the Achilles tendon was greater in the chronic group compared with all other groups (control group: 0.025 ± 0.009 cells/100 μm(2), acute group: 0.019 ± 0.005 cells/100 μm(2), chronic group: 0.067 ± 0.015, and insulin group: 0.004 ± 0.004 cells/100 μm(2), P < 0.05). Patellar tendon collagen content was ∼32% greater in the chronic and acute groups compared with the control or insulin groups (control group: 681 ± 63 μg collagen/mg dry wt, acute group: 938 ± 21 μg collagen/mg dry wt, chronic: 951 ± 52 μg collagen/mg dry wt, and insulin group: 596 ± 84 μg collagen/mg dry wt, P < 0.05). In contrast, patellar tendon hydroxylysyl pyridinoline cross linking and collagen fibril organization were unchanged by diabetes or insulin (P > 0.05). Our findings suggest that 10 wk of streptozotocin-induced diabetes does not alter rat tendon mechanical properties even with an increase in collagen content. Future studies could attempt to further address the mechanisms contributing to the increase in tendon problems noted in diabetic patients

  5. Latissimus Dorsi Tendon Transfer with GraftJacket® Augmentation to Increase Tendon Length for an Irreparable Rotator Cuff Tear

    PubMed Central

    2017-01-01

    Massive irreparable rotator cuff tears can be reconstructed with latissimus dorsi tendon transfers (LDTT). Although uncommon, the natural length of the latissimus dorsi tendon (LDT) could be insufficient for transfer even after adequate soft tissue releases. Descriptions of cases where grafts were needed to lengthen the LDT are therefore rare. We located only two reports of the use of an acellular dermal matrix to increase effective tendon length in tendon transfers about the shoulder: (1) GraftJacket patch for a pectoralis major tendon reconstruction and (2) ArthroFlex® patch for LDTT. Both of these brands of allograft patches are obtained from human cadavers. These products are usually used to cover soft tissue repairs and offer supplemental support rather than for increasing tendon length. Extending the LDTT with GraftJacket to achieve adequate length, to our knowledge, has not been reported in the literature. We report the case of a 50-year-old male who had a massive, irreparable left shoulder rotator cuff tear that was reconstructed with a LDTT. The natural length of his LDT was insufficient for transfer. This unexpected situation was rectified by sewing two patches of GraftJacket to the LDT. The patient had greatly improved shoulder function at two-year follow-up. PMID:28194290

  6. Electrocardiographic manifestation of the middle fibers/septal fascicle block: a consensus report.

    PubMed

    Bayés de Luna, Antonio; Riera, Andrés Pérez; Baranchuk, Adrian; Chiale, Pablo; Iturralde, Pedro; Pastore, Carlos; Barbosa, Raimundo; Goldwasser, Diego; Alboni, Paolo; Elizari, Marcelo

    2012-09-01

    There are fibers in the left ventricle (LV) (LV middle network) that in around one third of cases may be considered a true septal fascicle that arises from the common left bundle. Its presence and the evidence that there are 3 points of activation onset in the LV favor the quadrifascicular theory of the intraventricular activation of both ventricles. Since the 70s, different authors have suggested that the block of the left middle fibers (MS)/left septal fascicle may explain different electrocardiographic (ECG) patterns. The 2 hypothetically based criteria that are in some sense contradictory include: a) the lack of septal "q" wave due to first left and later posteriorly shifting of the horizontal plane loop and b) the presence of RS in lead V(2) (V(1)-V(2)) due to some anterior shifting of the horizontal plane vectorcardiogram loop. However, there are many evidence that the lack of septal q waves can be also explained by predivisional first-degree left bundle-branch block and that the RS pattern in the right precordial leads may be also explained by first-degree right bundle-branch block. The transient nature of these patterns favor the concept that some type of intraventricular conduction disturbance exists but a doubt remains about its location. Furthermore, the RS pattern could be explained by many different normal variants. To improve our understanding whether these patterns are due to MF/left septal fascicle block or other ventricular conduction disturbances (or both), it would be advisable: 1) To perform more histologic studies (heart transplant and necropsy) of the ventricular conduction system; 2) To repeat prior experimental studies using new methodology/technology to isolate the MF; and 3) To change the paradigm: do not try to demonstrate if the block of the fibers produces an ECG change but to study with new electroanatomical imaging techniques, if these ECG criteria previously described correlate or not with a delay of activation in the zone of the LV

  7. The role of stretching in tendon injuries.

    PubMed

    Witvrouw, E; Mahieu, N; Roosen, P; McNair, P

    2007-04-01

    The function of tendons can be classified into two categories: tensile force transmission, and storage and release of elastic energy during locomotion. The action of tendons in storing and releasing energy is mainly seen in sports activities with stretch-shortening cycles (SSCs). The more intense the SSC movements are (jumping-like activities), the more frequently tendon problems are observed. High SSC movements impose high loads on tendons. Consequently, tendons that frequently deal with high SSC motion require a high energy-absorbing capacity to store and release this large amount of elastic energy. As the elasticity of tendon structures is a leading factor in the amount of stored energy, prevention and rehabilitation programmes for tendon injuries should focus on increasing this tendon elasticity in athletes performing high SSC movements. Recently, it has been shown that ballistic stretching can significantly increase tendon elasticity. These findings have important clinical implications for treatment and prevention of tendon injuries.

  8. Selective effects of vibration on monosynaptic and late EMG responses in human soleus muscle after stimulation of the posterior tibial nerve or a tendon tap.

    PubMed Central

    Van Boxtel, A

    1979-01-01

    In normal subjects it was possible to evoke tendon and Hoffman reflexes which were followed by late EMG responses with a latency of 150-250 ms after the reflex stimuli. Analysis of the covariations of reflexes and late responses revealed that muscle spindle sensitivity and strength of the preceding twitch are not essential factors in determining the occurrence of the late responses as opposed to excitability changes within the spinal cord. Inhibition of monosynaptic reflexes and facilitation of late EMG responses to vibration indicate a difference in central pathways. A polysynaptic pathway may be involved in the late responses. PMID:159346

  9. Automatic measurement of pennation angle and fascicle length of gastrocnemius muscles using real-time ultrasound imaging.

    PubMed

    Zhou, Guang-Quan; Chan, Phoebe; Zheng, Yong-Ping

    2015-03-01

    Muscle imaging is a promising field of research to understand the biological and bioelectrical characteristics of muscles through the observation of muscle architectural change. Sonomyography (SMG) is a technique which can quantify the real-time architectural change of muscles under different contractions and motions with ultrasound imaging. The pennation angle and fascicle length are two crucial SMG parameters to understand the contraction mechanics at muscle level, but they have to be manually detected on ultrasound images frame by frame. In this study, we proposed an automatic method to quantitatively identify pennation angle and fascicle length of gastrocnemius (GM) muscle based on multi-resolution analysis and line feature extraction, which could overcome the limitations of tedious and time-consuming manual measurement. The method started with convolving Gabor wavelet specially designed for enhancing the line-like structure detection in GM ultrasound image. The resulting image was then used to detect the fascicles and aponeuroses for calculating the pennation angle and fascicle length with the consideration of their distribution in ultrasound image. The performance of this method was tested on computer simulated images and experimental images in vivo obtained from normal subjects. Tests on synthetic images showed that the method could identify the fascicle orientation with an average error less than 0.1°. The result of in vivo experiment showed a good agreement between the results obtained by the automatic and the manual measurements (r=0.94±0.03; p<0.001, and r=0.95±0.02, p<0.001). Furthermore, a significant correlation between the ankle angle and pennation angle (r=0.89±0.05; p<0.001) and fascicle length (r=-0.90±0.04; p<0.001) was found for the ankle plantar flexion. This study demonstrated that the proposed method was able to automatically measure the pennation angle and fascicle length of GM ultrasound images, which made it feasible to investigate

  10. Simultaneous bilateral patellar tendon rupture.

    PubMed

    Moura, Diogo Lino; Marques, José Pedro; Lucas, Francisco Manuel; Fonseca, Fernando Pereira

    2017-01-01

    Bilateral patellar tendon rupture is a rare entity, often associated with systemic diseases and patellar tendinopathy. The authors report a rare case of a 34-year-old man with simultaneous bilateral rupture of the patellar tendon caused by minor trauma. The patient is a retired basketball player with no past complaints of chronic knee pain and a history of steroid use. Surgical management consisted in primary end-to-end tendon repair protected temporarily with cerclage wiring, followed by a short immobilization period and intensive rehabilitation program. Five months after surgery, the patient was able to fully participate in sport activities.

  11. Rectus Femoris Tendon Calcification

    PubMed Central

    Zini, Raul; Panascì, Manlio; Papalia, Rocco; Franceschi, Francesco; Vasta, Sebastiano; Denaro, Vincenzo

    2014-01-01

    Background: Since it was developed, hip arthroscopy has become the favored treatment for femoroacetabular impingement. Due to recent considerable improvements, the indications for this technique have been widely extended. Injuries of the rectus femoris tendon origin, after an acute phase, could result in a chronic tendinopathy with calcium hydroxyapatite crystal deposition, leading to pain and loss of function. Traditionally, this condition is addressed by local injection of anesthetic and corticosteroids or, when conservative measures fail, by open excision of the calcific lesion by an anterior approach. Purpose: To assess whether arthroscopic excision of calcification of the proximal rectus is a safe and effective treatment. Study Design: Case series; Level of evidence, 4. Methods: Outcomes were studied from 6 top amateur athletes (age range, 30-43 years; mean, 32.6 years) affected by calcification of the proximal rectus who underwent arthroscopic excision of the calcification. Patients were preoperatively assessed radiographically, and diagnosis was confirmed by a 3-dimensional computed tomography scan. To evaluate the outcome, standardized hip rating scores were used pre- and postoperatively (at 6 and 12 months): the Hip disability and Osteoarthritis Outcome Score, Oxford Hip Score, and Modified Harris Hip Score. Moreover, visual analog scales (VAS) for pain, sport activity level (SAL), and activities of daily living (ADL) were also used. Results: One year after surgery, all patients reported satisfactory outcomes, with 3 of 6 rating their return-to-sport level as high as preinjury level, and the remaining 3 with a percentage higher than 80%. Five patients ranked their ability to carry on daily activities at 100%. Statistical analysis showed significant improvement of the Oxford Hip Score, the Modified Harris Hip Score, and all 3 VAS subscales (pain, SAL, and ADL) from pre- to latest postoperative assessment (P < .05). Conclusion: Arthroscopic excision of

  12. Evaluation and statistical inference for human connectomes.

    PubMed

    Pestilli, Franco; Yeatman, Jason D; Rokem, Ariel; Kay, Kendrick N; Wandell, Brian A

    2014-10-01

    Diffusion-weighted imaging coupled with tractography is currently the only method for in vivo mapping of human white-matter fascicles. Tractography takes diffusion measurements as input and produces the connectome, a large collection of white-matter fascicles, as output. We introduce a method to evaluate the evidence supporting connectomes. Linear fascicle evaluation (LiFE) takes any connectome as input and predicts diffusion measurements as output, using the difference between the measured and predicted diffusion signals to quantify the prediction error. We use the prediction error to evaluate the evidence that supports the properties of the connectome, to compare tractography algorithms and to test hypotheses about tracts and connections.

  13. A system and method to interface with multiple groups of axons in several fascicles of peripheral nerves

    PubMed Central

    Thota, Anil K.; Kuntaegowdanahalli, Sathyakumar; Starosciak, Amy K.; Abbas, James J.; Orbay, Jorge; Horch, Kenneth W.; Jung, Ranu

    2014-01-01

    Background Several neural interface technologies that stimulate and/or record from groups of axons have been developed. The longitudinal intrafascicular electrode (LIFE) is a fine wire that can provide access to a discrete population of axons within a peripheral nerve fascicle. Some applications require, or would benefit greatly from, technology that could provide access to multiple discrete sites in several fascicles. New Method The distributed intrafascicular multi-electrode (DIME) lead was developed to deploy multiple LIFEs to several fascicles. It consists of several (e.g. six) LIFEs that are coiled and placed in a sheath for strength and durability, with a portion left uncoiled to allow insertion at distinct sites. We have also developed a multi-lead multi-electrode (MLME) management system that includes a set of sheaths and procedures for fabrication and deployment. Results A prototype with 3 DIME leads was fabricated and tested in a procedure in a cadaver arm. The leads were successfully routed through skin and connective tissue and the deployment procedures were utilized to insert the LIFEs into fascicles of two nerves. Comparison with Existing Method(s) Most multi-electrode systems use a single-lead, multi-electrode design. For some applications, this design may be limited by the bulk of the multi-contact array and/or by the spatial distribution of the electrodes. Conclusion We have designed a system that can be used to access multiple sets of discrete groups of fibers that are spatially distributed in one or more fascicles of peripheral nerves. This system may be useful for neural-enabled prostheses or other applications. PMID:25092497

  14. Tensile properties of craniofacial tendons in the mature and aged zebrafish

    PubMed Central

    Shah, Rishita R.; Nerurkar, Nandan L.; Wang, Calvin; Galloway, Jenna L.

    2015-01-01

    The zebrafish Danio rerio is a powerful model for the study of development, regenerative biology, and human disease. However, the analysis of load-bearing tissues such as tendons and ligaments has been limited in this system. This is largely due to technical limitations that preclude accurate measurement of their mechanical properties. Here, we present a custom tensile testing system that applies nano-Newton scale forces to zebrafish tendons as small as 1 mm in length. Tendon properties were remarkably similar to mammalian tendons, including stress-strain nonlinearity and a linear modulus (515±152 MPa) that aligned closely with mammalian data. Additionally, a simple exponential constitutive law used to describe tendon mechanics was successfully fit to zebrafish tendons; the associated material constants agreed with literature values for mammalian tendons. Finally, mature and aged zebrafish comparisons revealed a significant decline in mechanical function with age. Based on the exponential constitutive model, age related changes were primarily caused by a reduction in nonlinearity (e.g. changes in collagen crimp or fiber recruitment). These findings demonstrate the utility of zebrafish as a model to study tendon biomechanics in health and disease. Moreover, these findings suggest that tendon mechanical behavior is highly conserved across vertebrates. PMID:25665155

  15. Pentadecapeptide BPC 157 enhances the growth hormone receptor expression in tendon fibroblasts.

    PubMed

    Chang, Chung-Hsun; Tsai, Wen-Chung; Hsu, Ya-Hui; Pang, Jong-Hwei Su

    2014-11-19

    BPC 157, a pentadecapeptide derived from human gastric juice, has been demonstrated to promote the healing of different tissues, including skin, muscle, bone, ligament and tendon in many animal studies. However, the underlying mechanism has not been fully clarified. The present study aimed to explore the effect of BPC 157 on tendon fibroblasts isolated from Achilles tendon of male Sprague-Dawley rat. From the result of cDNA microarray analysis, growth hormone receptor was revealed as one of the most abundantly up-regulated genes in tendon fibroblasts by BPC 157. BPC 157 dose- and time-dependently increased the expression of growth hormone receptor in tendon fibroblasts at both the mRNA and protein levels as measured by RT/real-time PCR and Western blot, respectively. The addition of growth hormone to BPC 157-treated tendon fibroblasts dose- and time-dependently increased the cell proliferation as determined by MTT assay and PCNA expression by RT/real-time PCR. Janus kinase 2, the downstream signal pathway of growth hormone receptor, was activated time-dependently by stimulating the BPC 157-treated tendon fibroblasts with growth hormone. In conclusion, the BPC 157-induced increase of growth hormone receptor in tendon fibroblasts may potentiate the proliferation-promoting effect of growth hormone and contribute to the healing of tendon.

  16. Pitfalls during biomechanical testing - Evaluation of different fixation methods for measuring tendons endurance properties.

    PubMed

    Hangody, Gy; Pánics, G; Szebényi, G; Kiss, R; Hangody, L; Pap, K

    2016-03-01

    The goal of the study was to find a proper technique to fix tendon grafts into an INSTRON loading machine. From 8 human cadavers, 40 grafts were collected. We removed the bone-patella tendon-bone grafts, the semitendinosus and gracilis tendons, the quadriceps tendon-bone grafts, the Achilles tendons, and the peroneus longus tendons from each lower extremity. We tested the tendon grafts with five different types of fixation devices: surgical thread (Premicron 3), general mounting clamp, wire mesh, cement fixation, and a modified clamp for an INSTRON loading machine. The mean failure load in case of surgical thread fixation was (381N ± 26N). The results with the general clamp were (527N ± 45N). The wire meshes were more promising (750N ± 21N), but did not reach the outcomes we desired. Easy slippages of the ends of the tendons from the cement encasements were observed (253N ± 18N). We then began to use Shi's clamp that could produce 977N ± 416N peak force. We combined Shi's clamp with freezing of the graft and the rupture of the tendon itself demonstrated an average force of 2198 N ± 773N. We determined that our modified frozen clamp fixed the specimens against high tensile forces.

  17. Tensile properties of craniofacial tendons in the mature and aged zebrafish.

    PubMed

    Shah, Rishita R; Nerurkar, Nandan L; Wang, Calvin C; Galloway, Jenna L

    2015-06-01

    The zebrafish Danio rerio is a powerful model for the study of development, regenerative biology, and human disease. However, the analysis of load-bearing tissues such as tendons and ligaments has been limited in this system. This is largely due to technical limitations that preclude accurate measurement of their mechanical properties. Here, we present a custom tensile testing system that applies nano-Newton scale forces to zebrafish tendons as small as 1 mm in length. Tendon properties were remarkably similar to mammalian tendons, including stress-strain nonlinearity and a linear modulus (515 ± 152 MPa) that aligned closely with mammalian data. Additionally, a simple exponential constitutive law used to describe tendon mechanics was successfully fit to zebrafish tendons; the associated material constants agreed with literature values for mammalian tendons. Finally, mature and aged zebrafish comparisons revealed a significant decline in mechanical function with age. Based on the exponential constitutive model, age-related changes were primarily caused by a reduction in nonlinearity (e.g., changes in collagen crimp or fiber recruitment). These findings demonstrate the utility of zebrafish as a model to study tendon biomechanics in health and disease. Moreover, these findings suggest that tendon mechanical behavior is highly conserved across vertebrates.

  18. Multilayered Electrospun Scaffolds for Tendon Tissue Engineering

    PubMed Central

    Chainani, Abby; Hippensteel, Kirk J.; Kishan, Alysha; Garrigues, N. William; Ruch, David S.; Guilak, Farshid

    2013-01-01

    Full-thickness rotator cuff tears are one of the most common causes of shoulder pain in people over the age of 65. High retear rates and poor functional outcomes are common after surgical repair, and currently available extracellular matrix scaffold patches have limited abilities to enhance new tendon formation. In this regard, tissue-engineered scaffolds may provide a means to improve repair of rotator cuff tears. Electrospinning provides a versatile method for creating nanofibrous scaffolds with controlled architectures, but several challenges remain in its application to tissue engineering, such as cell infiltration through the full thickness of the scaffold as well as control of cell growth and differentiation. Previous studies have shown that ligament-derived extracellular matrix may enhance differentiation toward a tendon or ligament phenotype by human adipose stem cells (hASCs). In this study, we investigated the use of tendon-derived extracellular matrix (TDM)-coated electrospun multilayered scaffolds compared to fibronectin (FN) or phosphate-buffered saline (PBS) coating for use in rotator cuff tendon tissue engineering. Multilayered poly(ɛ-caprolactone) scaffolds were prepared by sequentially collecting electrospun layers onto the surface of a grounded saline solution into a single scaffold. Scaffolds were then coated with TDM, FN, or PBS and seeded with hASCs. Scaffolds were maintained without exogenous growth factors for 28 days in culture and evaluated for protein content (by immunofluorescence and biochemical assay), markers of tendon differentiation, and tensile mechanical properties. The collagen content was greatest by day 28 in TDM-scaffolds. Gene expression of type I collagen, decorin, and tenascin C increased over time, with no effect of scaffold coating. Sulfated glycosaminoglycan and dsDNA contents increased over time in culture, but there was no effect of scaffold coating. The Young's modulus did not change over time, but yield strain

  19. Mechanical model of a single tendon finger

    NASA Astrophysics Data System (ADS)

    Rossi, Cesare; Savino, Sergio

    2013-10-01

    The mechanical model of a single tendon three phalanxes finger is presented. By means of the model both kinematic and dynamical behavior of the finger itself can be studied. This finger is a part of a more complex mechanical system that consists in a four finger grasping device for robots or in a five finger human hand prosthesis. A first prototype has been realized in our department in order to verify the real behavior of the model. Some results of both kinematic and dynamical behavior are presented.

  20. Structural and mechanical integrity of tendon-to-tendon attachments used in upper limb tendon transfer surgery.

    PubMed

    Tsiampa, Vassiliki A; Ignatiadis, Ioannis; Papalois, Apostolos; Givissis, Panayiotis; Christodoulou, Anastasios; Fridén, Jan

    2012-09-01

    Improved tendon-to-tendon suturing techniques allow for consistent and immediate activation of transferred muscle after surgery. A pre-requisite for early training after tendon transfer surgery is sufficient mechanical integrity of the tendon-to-tendon attachment. This in vitro study compared the mechanisms and magnitudes of load-to-failure response of two different repair techniques (side-to-side running, n = 7) and weave sutures (n = 8) in sheep front foot tendons. Tensile tests were performed by placing pre-conditioned tendons in a testing machine and stretching at a constant speed to failure. The length of the tendons overlap was the same (50 mm) for both repair techniques. The results of the load to failure tests showed that the side-to-side repairs were significantly stronger than the weave repairs. The failure mechanisms were also different. While the side-to-side attachment failed by longitudinal separation of tendon material of the donor tendon but with the fibres locked to the running sutures attached to the recipient tendon, the weave repairs failed by knot slipping or by suture pullout from the tendon substance. It is concluded that use of the side-to-side repair technique can provide early active training of new motors that not only prevent the formation of adhesions but also facilitate the voluntary recruitment of motors powering new functions before immobilisation-related swelling and stiffness restrain muscle contractions.

  1. A layered electrospun and woven surgical scaffold to enhance endogenous tendon repair.

    PubMed

    Hakimi, O; Mouthuy, P A; Zargar, N; Lostis, E; Morrey, M; Carr, A

    2015-10-01

    Surgical reattachments of tendon to bone in the rotator cuff are reported to fail in around 40% of cases. There are no adequate solutions to improve tendon healing currently available. Electrospun, sub-micron materials, have been extensively studied as scaffolds for tendon repair with promising results, but are too weak to be surgically implanted or to mechanically support the healing tendon. To address this, we developed a bonding technique that enables the processing of electrospun sheets into multi-layered, robust, implantable fabrics. Here, we show a first prototype scaffold created with this method, where an electrospun sheet was reinforced with a woven layer. The resulting scaffold presents a maximum suture pull out strength of 167N, closely matched with human rotator cuff tendons, and the desired nanofibre-mediated bioactivity in vitro and in vivo. This type of scaffold has potential for broader application for augmenting other soft tissues.

  2. Triceps tendon rupture in weight lifters.

    PubMed

    Sollender, J L; Rayan, G M; Barden, G A

    1998-01-01

    Triceps tendon avulsion injuries are rare. We report four weight lifters with triceps tendon raptures, two of whom had received local steroid injections for pain in the triceps. All four patients had taken oral anabolic steroids before injury. All patients had closed avulsion of the triceps tendon from its insertion into the olecranon. Three patients were injured while bench pressing heavy weights, and one patient was injured while swinging a baseball bat. Satisfactory results were achieved after surgical reinsertion of the tendon.

  3. Effects of corticosteroids and hyaluronic acid on torn rotator cuff tendons in vitro and in rats.

    PubMed

    Nakamura, Hidehiro; Gotoh, Masafumi; Kanazawa, Tomonoshin; Ohta, Keisuke; Nakamura, Keiichirou; Honda, Hirokazu; Ohzono, Hiroki; Shimokobe, Hisao; Mitsui, Yasuhiro; Shirachi, Isao; Okawa, Takahiro; Higuchi, Fujio; Shirahama, Masahiro; Shiba, Naoto; Matsueda, Satoko

    2015-10-01

    Corticosteroids (CS) or hyaluronic acid (HA) is used in subacromial injection for the conservative treatment of rotator cuff tears (RCT); this study addresses the question of how CS and HA affect the tendon tissue and fibroblasts in vitro and in rats. Cell proliferation assays were performed in human tendon fibroblasts from RCT. Rats underwent surgery to create RCT, and the surgical sites were injected with CS or HA. The rotator cuff tendons were subjected to biomechanical testing, microscopic and immunohistochemical analysis of proliferating cell nuclear antigen (PCNA), and ultrastructural analysis. Cell proliferation was significantly decreased with CS in vitro (p < 0.05). Maximal load of CS-treated tendons was significantly decreased compared with that of HA-treated tendons (p < 0.05), as well as PCNA(+) cells at 2 weeks (p < 0.05). Ultrastructural observations of the CS-treated rats detected apoptosis of tendon fibroblasts 24 h after surgery. Histological and biomechanical data 4 weeks after surgery were not significant among the three groups. Unlike HA, CS caused cell death, and inhibition of the proliferation of tendon fibroblasts, leading to a delay of tendon healing involved and a subsequent decrease of biomechanical strength at the surgical site.

  4. Staged tendon grafts and soft tissue coverage.

    PubMed

    Elliot, David

    2011-05-01

    The objective of the two-staged flexor tendon method is to improve the predictability of final results in difficult problems dealing with tendon reconstruction. This article reviews the evolution and benefits of this procedure. It also considers the use of the technique to help deal with problems requiring pulley and skin reconstruction simultaneously with re-constituting the flexor tendon system.

  5. Does the left superior longitudinal fascicle subserve language semantics? A brain electrostimulation study.

    PubMed

    Maldonado, Igor Lima; Moritz-Gasser, Sylvie; Duffau, Hugues

    2011-09-01

    Recent diffusion tensor imaging (DTI) tractography studies indicate that the supramarginal gyrus (SMG) represents a relay between frontal and temporal language sites. Some authors postulate that pathways connecting SMG to the posterior temporal lobe, i.e., the posterior part of the superior longitudinal fascicle (SLF) subserve semantic aspects of language. However, DTI provides only anatomic but not functional data. Therefore, it is impossible to conclude. Interestingly, intra-operative electrical mapping of cortical and subcortical language structures during tumor surgery is recognized as a reliable technique in functional neuroanatomy research. We mapped the underlying white matter of the SMG, especially the SLF, in 11 patients who underwent awake surgery for a glioma involving the left inferior parietal lobule. Using direct electrostimulation, we investigated the exact role of the SLF in language. Our findings indicate that the white matter under the inferior parietal lobule is highly involved in the dorsal phonological system. First, the SMG, connected to the ventral premotor cortex by horizontal fibers of the SLF, subserves articulatory processing, as demonstrated by dysarthria elicited by stimulation. Second, long arcuate fibers, found deeper in the white matter, subserve phonological processing, as supported by phonemic paraphasia induced by electrostimulation. Third, the most important result is that no semantic disturbances were elicited by stimulating the SLF, including its posterior part. Furthermore, no semantic disorders occurred postoperatively. Subcortical brain mapping by direct electrical stimulation does not provide arguments for a possible role of the left SLF in language semantic processing.

  6. Tau mediates microtubule bundle architectures mimicking fascicles of microtubules found in the axon initial segment

    PubMed Central

    Chung, Peter J.; Song, Chaeyeon; Deek, Joanna; Miller, Herbert P.; Li, Youli; Choi, Myung Chul; Wilson, Leslie; Feinstein, Stuart C.; Safinya, Cyrus R.

    2016-01-01

    Tau, an intrinsically disordered protein confined to neuronal axons, binds to and regulates microtubule dynamics. Although there have been observations of string-like microtubule fascicles in the axon initial segment (AIS) and hexagonal bundles in neurite-like processes in non-neuronal cells overexpressing Tau, cell-free reconstitutions have not replicated either geometry. Here we map out the energy landscape of Tau-mediated, GTP-dependent ‘active' microtubule bundles at 37 °C, as revealed by synchrotron SAXS and TEM. Widely spaced bundles (wall-to-wall distance Dw–w≈25–41 nm) with hexagonal and string-like symmetry are observed, the latter mimicking bundles found in the AIS. A second energy minimum (Dw–w≈16–23 nm) is revealed under osmotic pressure. The wide spacing results from a balance between repulsive forces, due to Tau's projection domain (PD), and a stabilizing sum of transient sub-kBT cationic/anionic charge–charge attractions mediated by weakly penetrating opposing PDs. This landscape would be significantly affected by charge-altering modifications of Tau associated with neurodegeneration. PMID:27452526

  7. Tau mediates microtubule bundle architectures mimicking fascicles of microtubules found in the axon initial segment

    SciTech Connect

    Chung, Peter J.; Song, Chaeyeon; Deek, Joanna; Miller, Herbert P.; Li, Youli; Choi, Myung Chul; Wilson, Leslie; Feinstein, Stuart C.; Safinya, Cyrus R.

    2016-07-25

    Tau, an intrinsically disordered protein confined to neuronal axons, binds to and regulates microtubule dynamics. Although there have been observations of string-like microtubule fascicles in the axon initial segment (AIS) and hexagonal bundles in neurite-like processes in non-neuronal cells overexpressing Tau, cell-free reconstitutions have not replicated either geometry. Here we map out the energy landscape of Tau-mediated, GTP-dependent ‘active’ microtubule bundles at 37°C, as revealed by synchrotron SAXS and TEM. Widely spaced bundles (wall-to-wall distance Dw–w≈25–41nm) with hexagonal and string-like symmetry are observed, the latter mimicking bundles found in the AIS. A second energy minimum (Dw–w≈16–23nm) is revealed under osmotic pressure. The wide spacing results from a balance between repulsive forces, due to Tau’s projection domain (PD), and a stabilizing sum of transient sub-kBT cationic/anionic charge–charge attractions mediated by weakly penetrating opposing PDs. In the end, we find that this landscape would be significantly affected by charge-altering modifications of Tau associated with neurodegeneration.

  8. Tau mediates microtubule bundle architectures mimicking fascicles of microtubules found in the axon initial segment

    DOE PAGES

    Chung, Peter J.; Song, Chaeyeon; Deek, Joanna; ...

    2016-07-25

    Tau, an intrinsically disordered protein confined to neuronal axons, binds to and regulates microtubule dynamics. Although there have been observations of string-like microtubule fascicles in the axon initial segment (AIS) and hexagonal bundles in neurite-like processes in non-neuronal cells overexpressing Tau, cell-free reconstitutions have not replicated either geometry. Here we map out the energy landscape of Tau-mediated, GTP-dependent ‘active’ microtubule bundles at 37°C, as revealed by synchrotron SAXS and TEM. Widely spaced bundles (wall-to-wall distance Dw–w≈25–41nm) with hexagonal and string-like symmetry are observed, the latter mimicking bundles found in the AIS. A second energy minimum (Dw–w≈16–23nm) is revealed under osmoticmore » pressure. The wide spacing results from a balance between repulsive forces, due to Tau’s projection domain (PD), and a stabilizing sum of transient sub-kBT cationic/anionic charge–charge attractions mediated by weakly penetrating opposing PDs. In the end, we find that this landscape would be significantly affected by charge-altering modifications of Tau associated with neurodegeneration.« less

  9. Achilles tendon reflex measuring system

    NASA Astrophysics Data System (ADS)

    Szebeszczyk, Janina; Straszecka, Joanna

    1995-06-01

    The examination of Achilles tendon reflex is widely used as a simple, noninvasive clinical test in diagnosis and pharmacological therapy monitoring in such diseases as: hypothyroidism, hyperthyroidism, diabetic neuropathy, the lower limbs obstructive angiopathies and intermittent claudication. Presented Achilles tendon reflect measuring system is based on the piezoresistive sensor connected with the cylinder-piston system. To determinate the moment of Achilles tendon stimulation a detecting circuit was used. The outputs of the measuring system are connected to the PC-based data acquisition board. Experimental results showed that the measurement accuracy and repeatability is good enough for diagnostics and therapy monitoring purposes. A user friendly, easy-to-operate measurement system fulfills all the requirements related to recording, presentation and storing of the patients' reflexograms.

  10. Multiscale analysis of morphology and mechanics in tail tendon from the ZDSD rat model of type 2 diabetes.

    PubMed

    Gonzalez, Armando Diaz; Gallant, Maxime A; Burr, David B; Wallace, Joseph M

    2014-02-07

    Type 2 diabetes (T2D) impacts multiple organ systems including the circulatory, renal, nervous and musculoskeletal systems. In collagen-based tissues, one mechanism that may be responsible for detrimental mechanical impacts of T2D is the formation of advanced glycation end products (AGEs) leading to increased collagen stiffness and decreased toughness, resulting in brittle tissue behavior. The purpose of this study was to investigate tendon mechanical properties from normal and diabetic rats at two distinct length scales, testing the hypothesis that increased stiffness and strength and decreased toughness at the fiber level would be associated with alterations in nanoscale morphology and mechanics. Individual fascicles from female Zucker diabetic Sprague-Dawley (ZDSD) rats had no differences in fascicle-level mechanical properties but had increased material-level strength and stiffness versus control rats (CD). At the nanoscale, collagen fibril D-spacing was shifted towards higher spacing values in diabetic ZDSD fibrils. The distribution of nanoscale modulus values was also shifted to higher values. Material-level strength and stiffness from whole fiber tests were increased in ZDSD tails. Correlations between nanoscale and microscale properties indicate a direct positive relationship between the two length scales, most notably in the relationship between nanoscale and microscale modulus. These findings indicate that diabetes-induced changes in material strength and modulus were driven by alterations at the nanoscale.

  11. Monitoring micrometer-scale collagen organization in rat-tail tendon upon mechanical strain using second harmonic microscopy.

    PubMed

    Goulam Houssen, Y; Gusachenko, I; Schanne-Klein, M-C; Allain, J-M

    2011-07-28

    We continuously monitored the microstructure of a rat-tail tendon during stretch/relaxation cycles. To that purpose, we implemented a new biomechanical device that combined SHG imaging and mechanical testing modalities. This multi-scale experimental device enabled simultaneous visualization of the collagen crimp morphology at the micrometer scale and measurement of macroscopic strain-stress response. We gradually increased the ultimate strain of the cycles and showed that preconditioning mostly occurs in the first stretching. This is accompanied by an increase of the crimp period in the SHG image. Our results indicate that preconditioning is due to a sliding of microstructures at the scale of a few fibrils and smaller, that changes the resting length of the fascicle. This sliding can reverse on long time scales. These results provide a proof of concept that continuous SHG imaging performed simultaneously with mechanical assay allows analysis of the relationship between macroscopic response and microscopic structure of tissues.

  12. The clinical effect of tendon repair for tendon spontaneous rupture after corticosteroid injection in hands

    PubMed Central

    Lu, Hui; Yang, Hu; Shen, Hui; Ye, Ganmin; Lin, Xiang-Jin

    2016-01-01

    Abstract Corticosteroid injections for hand tendinitis can lead to a rare significant complication of tendon spontaneous rupture. However, only sporadic cases were reported in the literature before. This study was designed to gauge the clinical effect of tendon repair in patients of tendon spontaneous rupture after corticosteroid injection and analyze our experience. This was a retrospective observational study of 13 patients (8 women and 5 men) operated between July 2011 and December 2015 for tendon spontaneous rupture after corticosteroid injection. Demographic data, clinical features, imaging data, and surgical treatments were carefully reviewed. The average age was 52.308 ± 15.381 years (range 29–71). The average injection times were 2.538 ± 1.664 times (range 1–6). The average rupture time (after last injection) was 10.923 ± 9.500 weeks (range 3–32). Nine patients were treated by tendon suture (69% of cases), and 4 patients were treated by tendon grafting (31% of cases). All patients received follow-up in our outpatient clinic. The sites of the tendon rupture (15 tendons of 13 patients had involved) include extensor pollicis longus (6 tendons, 40% of cases), extensor digiti quinti and extensor digiti minimi (4 tendons, 27% of cases), ring finger of extensor digitorum communis (3 tendons, 20% of cases), and middle finger of extensor digitorum communis (2 tendons, 13% of cases). Two patients who had tendon adhesion (15% of cases) were treated by tendon release. One patient who had tendon rerupture (8% of cases) was treated by tendon grafting. No patient had complications of infections, vascular, or nerve injury. Tendon spontaneous rupture is a serious complication after corticosteroid injection for tendinitis. Rigid standard of corticosteroid injection is very important. Magnetic resonance imaging was contributory to preoperative assess tendon defect and can be used to monitor healing quality of tendons during the follow-up. PMID:27741145

  13. New technical procedure involving Achilles tendon rupture treatment through transcutaneous suture.

    PubMed

    TarniŢă, DănuŢ Nicolae; TarniŢă, Daniela; Grecu, Dan Cristian; Calafeteanu, Dan Marian; Căpitănescu, Bogdan

    2016-01-01

    The Achilles tendon is the widest tendon of the human body. Achilles tendon belongs to the extrasynovial tendons group and this allows it a faster recovery, thanks to local hematoma from the peritenon, necessary for the scarification. We concluded that in Achilles tendon rupture treatment it is essential to maintain the tendon covering skin integrity, the peritendinous integrity, to maintain the local hematoma formed during and after tendon rupture, reattaching the ruptured tendon heads and maintain them in this position by suturing them and by relaxing the sural triceps muscle. The percutaneous suture requires five pairs of mirror micro-incisions (5 mm) on one side and the other of the tendon. It is necessary for one of the pairs to be placed to the rupture level. With a surgical needle, we arm the proximal and distal heads of the tendon by different threads. By traction and muscular relaxation, we bring in contact the two ruptured heads and then we knot together the arming threads. The inferior member was cast immobilized in relaxing position for the sural triceps muscle for a 45 days period. Using this technique, we have operated 15 cases in our Clinic. In all the cases, we obtained a healing by first intention of the tegument micro-incisions. After the cast immobilization suppression, during 30 days the patients were in a recovery program. At the end of this program, they have recovered completely the dorsal and plantar flexion and the walking. In four months after the surgery, the esthetic of the area is completely restored, this technique being the only surgical technique that realizes this recovery.

  14. Bioreactor Design for Tendon/Ligament Engineering

    PubMed Central

    Wang, Tao; Gardiner, Bruce S.; Lin, Zhen; Rubenson, Jonas; Kirk, Thomas B.; Wang, Allan; Xu, Jiake

    2013-01-01

    Tendon and ligament injury is a worldwide health problem, but the treatment options remain limited. Tendon and ligament engineering might provide an alternative tissue source for the surgical replacement of injured tendon. A bioreactor provides a controllable environment enabling the systematic study of specific biological, biochemical, and biomechanical requirements to design and manufacture engineered tendon/ligament tissue. Furthermore, the tendon/ligament bioreactor system can provide a suitable culture environment, which mimics the dynamics of the in vivo environment for tendon/ligament maturation. For clinical settings, bioreactors also have the advantages of less-contamination risk, high reproducibility of cell propagation by minimizing manual operation, and a consistent end product. In this review, we identify the key components, design preferences, and criteria that are required for the development of an ideal bioreactor for engineering tendons and ligaments. PMID:23072472

  15. Inferring Muscle-Tendon Unit Power from Ankle Joint Power during the Push-Off Phase of Human Walking: Insights from a Multiarticular EMG-Driven Model

    PubMed Central

    2016-01-01

    Introduction Inverse dynamics joint kinetics are often used to infer contributions from underlying groups of muscle-tendon units (MTUs). However, such interpretations are confounded by multiarticular (multi-joint) musculature, which can cause inverse dynamics to over- or under-estimate net MTU power. Misestimation of MTU power could lead to incorrect scientific conclusions, or to empirical estimates that misguide musculoskeletal simulations, assistive device designs, or clinical interventions. The objective of this study was to investigate the degree to which ankle joint power overestimates net plantarflexor MTU power during the Push-off phase of walking, due to the behavior of the flexor digitorum and hallucis longus (FDHL)–multiarticular MTUs crossing the ankle and metatarsophalangeal (toe) joints. Methods We performed a gait analysis study on six healthy participants, recording ground reaction forces, kinematics, and electromyography (EMG). Empirical data were input into an EMG-driven musculoskeletal model to estimate ankle power. This model enabled us to parse contributions from mono- and multi-articular MTUs, and required only one scaling and one time delay factor for each subject and speed, which were solved for based on empirical data. Net plantarflexing MTU power was computed by the model and quantitatively compared to inverse dynamics ankle power. Results The EMG-driven model was able to reproduce inverse dynamics ankle power across a range of gait speeds (R2 ≥ 0.97), while also providing MTU-specific power estimates. We found that FDHL dynamics caused ankle power to slightly overestimate net plantarflexor MTU power, but only by ~2–7%. Conclusions During Push-off, FDHL MTU dynamics do not substantially confound the inference of net plantarflexor MTU power from inverse dynamics ankle power. However, other methodological limitations may cause inverse dynamics to overestimate net MTU power; for instance, due to rigid-body foot assumptions. Moving

  16. Influence of muscle-tendon unit structure on rate of force development during the squat, countermovement, and drop jumps.

    PubMed

    Earp, Jacob E; Kraemer, William J; Cormie, Prue; Volek, Jeffery S; Maresh, Carl M; Joseph, Michael; Newton, Robert U

    2011-02-01

    Previous research has highlighted the importance of muscle and tendon structure to stretch shortening cycle performance. However, the relationships between muscle and tendon structure to performance are highly dependent on the speed and intensity of the movement. The purpose of this study was to determine if muscle and tendon structure is associated with the rate of force development (RFD) throughout static squat jump (SJ), countermovement jump (CMJ), and drop jump (DJ; 30-cm height). Twenty-five strength- and power-trained men participated in the study. Using ultrasonography, vastus lateralis (VL) and gastrocnemius (GAS) pennation (PEN) and fascicle length (FL), and Achilles tendon (AT) thickness and length were measured. Subjects then performed SJ, CMJ, and DJ, during which RFD was calculated over time 5 distinct time intervals. During CMJs, early RFD could be predicted between 0 and 10 milliseconds by both GAS-FL (r² = 0.213, β = 0.461) and AT-length (r² = 0.191, β = 20.438). Between 10 and 30 milliseconds GAS-FL was a significant predictor of CMJ-RFD (r² = 0.218, β = 0.476). During DJ, initial RFD (0-10 milliseconds) could be significantly predicted by GAS-FL (r² = 0.185, β = 20.434), VL-PEN (r² = 0.189, β = 0.435), and GAS-PEN (r² = 0.188, β = 0.434). These findings suggest that longer ATs may have increased elasticity, which can decrease initial RFD during CMJ; thus, their use in talent identification is not recommended. The GAS fascicle length had an intensity-dependent relationship with RFD, serving to positively predict RFD during early CMJs and an inverse predictor during early DJs. During DDJs, subjects with greater PEN were better able to redirected initial impact forces. Although both strength and plyometric training have been shown to increase FL, only heavy strength training has been shown to increase PEN. Thus, when a high eccentric load or multiple jumps are required, heavy strength training might be used to elicit muscular adaptations

  17. Chitosan prevents adhesion during rabbit flexor tendon repair via the sirtuin 1 signaling pathway.

    PubMed

    Chen, Qiang; Lu, Hui; Yang, Hu

    2015-09-01

    Chitosan has been demonstrated to exert potent anti-adhesive activity during tendon repair; however, the underlying molecular mechanisms remain unclear. The present study aimed to investigate the preventive effects of chitosan on adhesion in rabbit tendon repair, and to investigate the role of the sirtuin (SIRT)1 signaling pathway in this process. A total of 30 rabbits were divided randomly into three equal groups: Group 1, saline treatment; group 2, chitosan treatment; and group 3, chitosan + nicotinamide treatment. The flexor tendon of each of the rabbits was injured, and subsequently each rabbit was injected with the one of the reagents. Six weeks post‑surgery, all of the rabbits were sacrificed and their flexor tendons were harvested for subsequent evaluation of adhesion. Western blotting was used to determine the protein expression levels of specific signaling molecules. An MTT assay was conducted to evaluate the viability of human tenocytes and flow cytometry was used to analyze the apoptotic rate of the cells. The present study demonstrated that treatment with chitosan relieved adhesion in the rabbits with flexor tendon injuries. In addition, chitosan treatment increased SIRT1 expression, and reduced acetylated p65 and p53 expression in the tendons. The effects of chitosan on the tendons were attenuated by treatment with nicotinamide (a SIRT1 inhibitor). In the human tenocytes, pretreatment with chitosan resulted in an inhibition of interleukin (IL)‑1β‑induced apoptosis. Furthermore, chitosan reversed the IL‑1β‑induced downregulation of SIRT1 and upregulation of acetylated p65 and p53. Furthermore, downregulation of Sirt1 by RNA interference abrogated the effects of chitosan on the levels of p65 and p53 acetylation, and the rate of tenocyte apoptosis. In conclusion, chitosan treatment prevented adhesion via the SIRT1 signaling pathway during rabbit flexor tendon repair. These results indicate that SIRT1 may be targeted for therapeutic

  18. Informing tendon tissue engineering with embryonic development.

    PubMed

    Glass, Zachary A; Schiele, Nathan R; Kuo, Catherine K

    2014-06-27

    Tendon is a strong connective tissue that transduces muscle-generated forces into skeletal motion. In fulfilling this role, tendons are subjected to repeated mechanical loading and high stress, which may result in injury. Tissue engineering with stem cells offers the potential to replace injured/damaged tissue with healthy, new living tissue. Critical to tendon tissue engineering is the induction and guidance of stem cells towards the tendon phenotype. Typical strategies have relied on adult tissue homeostatic and healing factors to influence stem cell differentiation, but have yet to achieve tissue regeneration. A novel paradigm is to use embryonic developmental factors as cues to promote tendon regeneration. Embryonic tendon progenitor cell differentiation in vivo is regulated by a combination of mechanical and chemical factors. We propose that these cues will guide stem cells to recapitulate critical aspects of tenogenesis and effectively direct the cells to differentiate and regenerate new tendon. Here, we review recent efforts to identify mechanical and chemical factors of embryonic tendon development to guide stem/progenitor cell differentiation toward new tendon formation, and discuss the role this work may have in the future of tendon tissue engineering.

  19. Informing tendon tissue engineering with embryonic development

    PubMed Central

    Glass, Zachary A.; Schiele, Nathan R.; Kuo, Catherine K.

    2014-01-01

    Tendon is a strong connective tissue that transduces muscle-generated forces into skeletal motion. In fulfilling this role, tendons are subjected to repeated mechanical loading and high stress, which may result in injury. Tissue engineering with stem cells offers the potential to replace injured/damaged tissue with healthy, new living tissue. Critical to tendon tissue engineering is the induction and guidance of stem cells towards the tendon phenotype. Typical strategies have relied on adult tissue homeostatic and healing factors to influence stem cell differentiation, but have yet to achieve tissue regeneration. A novel paradigm is to use embryonic developmental factors as cues to promote tendon regeneration. Embryonic tendon progenitor cell differentiation in vivo is regulated by a combination of mechanical and chemical factors. We propose that these cues will guide stem cells to recapitulate critical aspects of tenogenesis and effectively direct the cells to differentiate and regenerate new tendon. Here, we review recent efforts to identify mechanical and chemical factors of embryonic tendon development to guide stem/progenitor cell differentiation toward new tendon formation, and discuss the role this work may have in the future of tendon tissue engineering. PMID:24484642

  20. Timing matters: tuning the mechanics of a muscle-tendon unit by adjusting stimulation phase during cyclic contractions.

    PubMed

    Sawicki, Gregory S; Robertson, Benjamin D; Azizi, Emanuel; Roberts, Thomas J

    2015-10-01

    A growing body of research on the mechanics and energetics of terrestrial locomotion has demonstrated that elastic elements acting in series with contracting muscle are critical components of sustained, stable and efficient gait. Far fewer studies have examined how the nervous system modulates muscle-tendon interaction dynamics to optimize 'tuning' or meet varying locomotor demands. To explore the fundamental neuromechanical rules that govern the interactions between series elastic elements (SEEs) and contractile elements (CEs) within a compliant muscle-tendon unit (MTU), we used a novel work loop approach that included implanted sonomicrometry crystals along muscle fascicles. This enabled us to decouple CE and SEE length trajectories when cyclic strain patterns were applied to an isolated plantaris MTU from the bullfrog (Lithobates catesbeianus). Using this approach, we demonstrate that the onset timing of muscle stimulation (i.e. stimulation phase) that involves a symmetrical MTU stretch-shorten cycle during active force production results in net zero mechanical power output, and maximal decoupling of CE and MTU length trajectories. We found it difficult to 'tune' the muscle-tendon system for strut-like isometric force production by adjusting stimulation phase only, as the zero power output condition involved significant positive and negative mechanical work by the CE. A simple neural mechanism - adjusting muscle stimulation phase - could shift an MTU from performing net zero to net positive (energy producing) or net negative (energy absorbing) mechanical work under conditions of changing locomotor demand. Finally, we show that modifications to the classical work loop paradigm better represent in vivo muscle-tendon function during locomotion.

  1. Timing matters: tuning the mechanics of a muscle–tendon unit by adjusting stimulation phase during cyclic contractions

    PubMed Central

    Sawicki, Gregory S.; Robertson, Benjamin D.; Azizi, Emanuel; Roberts, Thomas J.

    2015-01-01

    ABSTRACT A growing body of research on the mechanics and energetics of terrestrial locomotion has demonstrated that elastic elements acting in series with contracting muscle are critical components of sustained, stable and efficient gait. Far fewer studies have examined how the nervous system modulates muscle–tendon interaction dynamics to optimize ‘tuning’ or meet varying locomotor demands. To explore the fundamental neuromechanical rules that govern the interactions between series elastic elements (SEEs) and contractile elements (CEs) within a compliant muscle–tendon unit (MTU), we used a novel work loop approach that included implanted sonomicrometry crystals along muscle fascicles. This enabled us to decouple CE and SEE length trajectories when cyclic strain patterns were applied to an isolated plantaris MTU from the bullfrog (Lithobates catesbeianus). Using this approach, we demonstrate that the onset timing of muscle stimulation (i.e. stimulation phase) that involves a symmetrical MTU stretch–shorten cycle during active force production results in net zero mechanical power output, and maximal decoupling of CE and MTU length trajectories. We found it difficult to ‘tune’ the muscle–tendon system for strut-like isometric force production by adjusting stimulation phase only, as the zero power output condition involved significant positive and negative mechanical work by the CE. A simple neural mechanism – adjusting muscle stimulation phase – could shift an MTU from performing net zero to net positive (energy producing) or net negative (energy absorbing) mechanical work under conditions of changing locomotor demand. Finally, we show that modifications to the classical work loop paradigm better represent in vivo muscle–tendon function during locomotion. PMID:26232413

  2. Analytic model to predict the strength of tendon repairs.

    PubMed

    Lotz, J C; Hariharan, J S; Diao, E

    1998-07-01

    We developed an analytic model to predict suture load-sharing immediately after flexor tendon repair in the hand. Tendon repair was mathematically modeled as two nonlinear springs in parallel, representing separate core and peripheral sutures that were in series with a third nonlinear spring representing the tendon. To serve as a basis for, and validation of, our analytic model, fresh human flexor digitorum profundus tendons were harvested and mechanically tested either intact or after surgical repair in a variety of ways: core suture alone, superficial peripheral suture alone, deep peripheral suture alone, core suture plus superficial peripheral suture, and core suture plus deep peripheral suture. The stiffness and strength of the composite repairs predicted with use of the analytic model were comparable with those determined experimentally. Furthermore, the model predicted inequities in suture load-sharing, with 64% of the applied load carried by the peripheral suture when it was placed superficially, as compared with 77% when the peripheral suture was placed deep. Our results demonstrate a disparity in load-sharing within composite suture systems, the rectification of which may lead to significant improvement in the repair strength. To this end, we expect that our analytic model will serve as a basis for the design of more efficient, and consequently stronger, suture techniques.

  3. The Use of 2D Ultrasound Elastography for Measuring Tendon Motion and Strain

    PubMed Central

    Slane, Laura Chernak; Thelen, Darryl G.

    2014-01-01

    The goal of the current study was to investigate the fidelity of a 2D ultrasound elastography method for the measurement of tendon motion and strain. Ultrasound phantoms and ex vivo porcine flexor tendons were cyclically stretched to 4% strain while cine ultrasound radiofrequency (RF) data and video data were simultaneously collected. 2D ultrasound elastography was used to estimate tissue motion and strain from RF data, and surface tissue motion and strain were separately estimated using digital image correlation (DIC). There were strong correlations (R2 > 0.97) between DIC and RF measurements of phantom displacement and strain, and good agreement in estimates of peak phantom strain (DIC: 3.5 ± 0.2%; RF: 3.7 ± 0.1%). For tendon, elastographic estimates of displacement profiles also correlated well with DIC measurements (R2 > 0.92), and exhibited similar estimated peak tendon strain (DIC: 2.6 ± 1.4%; RF: 2.2 ± 1.3%). Elastographic tracking with B-Mode images tended to under-predict peak strain for both the phantom and tendon. This study demonstrates the capacity to use quantitative elastographic techniques to measure tendon displacement and strain within an ultrasound image window. The approach may be extendible to in vivo use on humans, which would allow for the non-invasive analysis of tendon deformation in both normal and pathological states. PMID:24388164

  4. In-vitro tensile testing machine for vibration study of fresh rabbit Achilles tendon

    NASA Astrophysics Data System (ADS)

    Revel, Gian M.; Scalise, Alessandro; Scalise, Lorenzo; Pianosi, Antonella

    2001-10-01

    A lot of people, overall athletic one suffer from tendinitis or complete rupture of the Achilles tendon. This structure becomes inflamed and damaged mainly from a variety of mechanical forces and sometimes due to metabolic problems, such as diabetes or arthritis. Over the past three decades extensive studies have been performed on the structural and mechanical properties of Achilles tendon trying to explain the constitutive equations to describe and foresee tendon behavior. Among the various mechanical parameters, the vibrational behavior is also of interest. Several investigations are performed in order to study how the Achilles tendon vibrations influence the response of the muscle proprioception and human posture. The present article describes how in vitro tensile experiments can be performed, taking into account the need to simulate physiological condition of Achilles tendon and thus approaching some opened problems in the design of the experimental set-up. A new system for evaluating tendon vibrations by non contact techniques is proposed. Preliminary simple elongation tests are made extracting the main mechanical parameters: stress and strain at different fixed stretches, in order to characterize the tissue. Finally, a vibration study is made at each pretensioned tendon level evaluating the oscillating curves caused by a small hammer.

  5. Bifurcated popliteus tendon: a descriptive arthroscopic study

    PubMed Central

    Ginés-Cespedosa, Albert; Monllau, Joan C.

    2008-01-01

    The objective of this study was to confirm the presence and frequency of a bifurcation of the popliteus tendon. The popliteus tendon has received attention due to its important function as a knee stabiliser. Several anatomical variants have recently been reported, one of them being a bifurcated tendon. However, the actual frequency as well as the possible role of this particular variant is still unknown. We prospectively analysed a series of 1,569 arthroscopies between January 2005 to December 2007. Six asymptomatic bifurcated popliteus tendons were found. No alterations in the magnetic resonance imaging were seen and no clinical signs (related to the popliteus tendon) were observed in these patients before surgery. In all cases the morphological variant was found by chance. Our results suggest that the presence of a bifurcated popliteus tendon is a fact and that its frequency, not previously reported, should not be ignored. PMID:18998130

  6. Mesenchymal stem cell applications to tendon healing

    PubMed Central

    Chaudhury, Salma

    2012-01-01

    Summary Tendons are often subject to age related degenerative changes that coincide with a diminished regenerative capacity. Torn tendons often heal by forming scar tissue that is structurally weaker than healthy native tendon tissue, predisposing to mechanical failure. There is increasing interest in providing biological stimuli to increase the tendon reparative response. Stem cells in particular are an exciting and promising prospect as they have the potential to provide appropriate cellular signals to encourage neotendon formation during repair rather than scar tissue. Currently, a number of issues need to be investigated further before it can be determined whether stem cells are an effective and safe therapeutic option for encouraging tendon repair. This review explores the in-vitro and invivo evidence assessing the effect of stem cells on tendon healing, as well as the potential clinical applications. PMID:23738300

  7. Quadriceps tendon allografts as an alternative to Achilles tendon allografts: a biomechanical comparison.

    PubMed

    Mabe, Isaac; Hunter, Shawn

    2014-12-01

    Quadriceps tendon with a patellar bone block may be a viable alternative to Achilles tendon for anterior cruciate ligament reconstruction (ACL-R) if it is, at a minimum, a biomechanically equivalent graft. The objective of this study was to directly compare the biomechanical properties of quadriceps tendon and Achilles tendon allografts. Quadriceps and Achilles tendon pairs from nine research-consented donors were tested. All specimens were processed to reduce bioburden and terminally sterilized by gamma irradiation. Specimens were subjected to a three phase uniaxial tension test performed in a custom environmental chamber to maintain the specimens at a physiologic temperature (37 ± 2 °C) and misted with a 0.9 % NaCl solution. There were no statistical differences in seven of eight structural and mechanical between the two tendon types. Quadriceps tendons exhibited a significantly higher displacement at maximum load and significantly lower stiffness than Achilles tendons. The results of this study indicated a biomechanical equivalence of aseptically processed, terminally sterilized quadriceps tendon grafts with bone block to Achilles tendon grafts with bone block. The significantly higher displacement at maximum load, and lower stiffness observed for quadriceps tendons may be related to the failure mode. Achilles tendons had a higher bone avulsion rate than quadriceps tendons (86 % compared to 12 %, respectively). This was likely due to observed differences in bone block density between the two tendon types. This research supports the use of quadriceps tendon allografts in lieu of Achilles tendon allografts for ACL-R.

  8. Repeated freeze-thaw cycles reduce the survival rate of osteocytes in bone-tendon constructs without affecting the mechanical properties of tendons.

    PubMed

    Suto, Kaori; Urabe, Ken; Naruse, Kouji; Uchida, Kentaro; Matsuura, Terumasa; Mikuni-Takagaki, Yuko; Suto, Mitsutoshi; Nemoto, Noriko; Kamiya, Kentaro; Itoman, Moritoshi

    2012-03-01

    Frozen bone-patellar tendon bone allografts are useful in anterior cruciate ligament reconstruction as the freezing procedure kills tissue cells, thereby reducing immunogenicity of the grafts. However, a small portion of cells in human femoral heads treated by standard bone-bank freezing procedures survive, thus limiting the effectiveness of allografts. Here, we characterized the survival rates and mechanisms of cells isolated from rat bones and tendons that were subjected to freeze-thaw treatments, and evaluated the influence of these treatments on the mechanical properties of tendons. After a single freeze-thaw cycle, most cells isolated from frozen bone appeared morphologically as osteocytes and expressed both osteoblast- and osteocyte-related genes. Transmission electron microscopic observation of frozen cells using freeze-substitution revealed that a small number of osteocytes maintained large nuclei with intact double membranes, indicating that these osteocytes in bone matrix were resistant to ice crystal formation. We found that tendon cells were completely killed by a single freeze-thaw cycle, whereas bone cells exhibited a relatively high survival rate, although survival was significantly reduced after three freeze-thaw cycles. In patella tendons, the ultimate stress, Young's modulus, and strain at failure showed no significant differences between untreated tendons and those subjected to five freeze-thaw cycles. In conclusion, we identified that cells surviving after freeze-thaw treatment of rat bones were predominantly osteocytes. We propose that repeated freeze-thaw cycles could be applied for processing bone-tendon constructs prior to grafting as the treatment did not affect the mechanical property of tendons and drastically reduced surviving osteocytes, thereby potentially decreasing allograft immunogenecity.

  9. Structure and function of tuna tail tendons.

    PubMed

    Shadwick, Robert E; Rapoport, H Scott; Fenger, Joelle M

    2002-12-01

    The caudal tendons in tunas and other scombrid fish link myotomal muscle directly to the caudal fin rays, and thus serve to transfer muscle power to the hydrofoil-like tail during swimming. These robust collagenous tendons have structural and mechanical similarity to tendons found in other vertebrates, notably the leg tendons of terrestrial mammals. Biochemical studies indicate that tuna tendon collagen is composed of the (alpha1)(2),alpha2 heterotrimer that is typical of vertebrate Type I collagen, while tuna skin collagen has the unusual alpha1,alpha2,alpha3 trimer previously described in the skin of some other teleost species. Tuna collagen, like that of other fish, has high solubility due to the presence of an acid-labile intermolecular cross-link. Unlike collagen in mammalian tendons, no differences related to cross-link maturation were detected among tendons in tuna ranging from 0.05 to 72 kg (approx. 0.25-6 years). Tendons excised post-mortem were subjected to load cycling to determine the modulus of elasticity and resilience (mean of 1.3 GPa and 90%, respectively). These material properties compare closely to those of leg tendons from adult mammals that can function as effective biological springs in terrestrial locomotion, but the breaking strength is substantially lower. Peak tendon forces recorded during steady swimming appear to impose strains of much less than 1% of tendon length, and no more than 1.5% during bursts. Thus, the caudal tendons in tunas do not appear to function as elastic storage elements, even at maximal swimming effort.

  10. Application of a Rat Hindlimb Model: A Prediction of Force Spaces Reachable Through Stimulation of Nerve Fascicles

    PubMed Central

    Johnson, Will L.; Jindrich, Devin L.; Zhong, Hui; Roy, Roland R.

    2011-01-01

    A device to generate standing or locomotion through chronically placed electrodes has not been fully developed due in part to limitations of clinical experimentation and the high number of muscle activation inputs of the leg. We investigated the feasibility of functional electrical stimulation paradigms that minimize the input dimensions for controlling the limbs by stimulating at nerve fascicles, utilizing a model of the rat hindlimb which combined previously collected morphological data with muscle physiological parameters presented herein. As validation of the model we investigated the suitability of a lumped-parameter model for prediction of muscle activation during dynamic tasks. Using the validated model we found that the space of forces producible through activation of muscle groups sharing common nerve fascicles was nonlinearly dependent on the number of discrete muscle groups that could be individually activated (equivalently, the neuroanatomical level of activation). Seven commonly innervated muscle groups were sufficient to produce 78% of the force space producible through individual activation of the 42 modeled hindlimb muscles. This novel, neuroanatomically derived reduction in input dimension emphasizes the potential to simplify controllers for functional electrical stimulation to improve functional recovery after a neuromuscular injury. PMID:21244999

  11. Tendon mineralization is accelerated bilaterally and creep of contralateral tendons is increased after unilateral needle injury of murine achilles tendons.

    PubMed

    O'Brien, Etienne John Ogilvy; Shrive, Nigel G; Rosvold, Joshua M; Thornton, Gail M; Frank, Cyril B; Hart, David A

    2013-10-01

    Heterotopic mineralization may result in tendon weakness, but effects on other biomechanical responses have not been reported. We used a needle injury, which accelerates spontaneous mineralization of murine Achilles tendons, to test two hypotheses: that injured tendons would demonstrate altered biomechanical responses; and that unilateral injury would accelerate mineralization bilaterally. Mice underwent left hind (LH) injury (I; n = 11) and were euthanized after 20 weeks along with non-injured controls (C; n = 9). All hind limbs were examined by micro computed tomography followed by biomechanical testing (I = 7 and C = 6). No differences were found in the biomechanical responses of injured tendons compared with controls. However, the right hind (RH) tendons contralateral to the LH injury exhibited greater static creep strain and total creep strain compared with those LH tendons (p ≤ 0.045) and RH tendons from controls (p ≤ 0.043). RH limb lesions of injured mice were three times larger compared with controls (p = 0.030). Therefore, despite extensive mineralization, changes to the responses we measured were limited or absent 20 weeks postinjury. These results also suggest that bilateral occurrence should be considered where tendon mineralization is identified clinically. This experimental system may be useful to study the mechanisms of bilateral new bone formation in tendinopathy and other conditions.

  12. Single-stage reconstruction of flexor tendons with vascularized tendon transfers.

    PubMed

    Cavadas, P C; Pérez-García, A; Thione, A; Lorca-García, C

    2015-03-01

    The reconstruction of finger flexor tendons with vascularized flexor digitorum superficialis (FDS) tendon grafts (flaps) based on the ulnar vessels as a single stage is not a popular technique. We reviewed 40 flexor tendon reconstructions (four flexor pollicis longus and 36 finger flexors) with vascularized FDS tendon grafts in 38 consecutive patients. The donor tendons were transferred based on the ulnar vessels as a single-stage procedure (37 pedicled flaps, three free flaps). Four patients required composite tendon and skin island transfer. Minimum follow-up was 12 months, and functional results were evaluated using a total active range of motion score. Multiple linear regression analysis was performed to evaluate the factors that could be associated with the postoperative total active range of motion. The average postoperative total active range of motion (excluding the thumbs) was 178.05° (SD 50°). The total active range of motion was significantly lower for patients who were reconstructed with free flaps and for those who required composite tendon and skin island flap. Age, right or left hand, donor/motor tendon and pulley reconstruction had no linear effect on total active range of motion. Overall results were comparable with a published series on staged tendon grafting but with a lower complication rate. Vascularized pedicled tendon grafts/flaps are useful in the reconstruction of defects of finger flexor tendons in a single stage, although its role in the reconstructive armamentarium remains to be clearly established.

  13. Calcific tendonitis of the tibialis posterior tendon at the navicular attachment

    PubMed Central

    Harries, Luke; Kempson, Susan; Watura, Roland

    2011-01-01

    Calcific tendinosis (tendonosis/tendonitis) is a condition which results from the deposition of calcium hydroxyapatite crystals in any tendon of the body. Calcific tendonitis usually presents with pain, which can be exacerbated by prolonged use of the affected tendon. We report a case of calcific tendinosis in the posterior tibialis tendon at the navicular insertion. The pathology is rare in the foot, and extremely rare in the tibialis posterior tendon, indeed there are only 2 reported in the published literature. This case report highlights the need to consider calcific tendinosis in the foot despite its rarity. If this diagnosis is considered early, appropriate investigations can then be requested and unnecessary biopsies, use of antibiotics and surgery can be avoided. We also discuss possible causes of calcific tendinosis in the tibialis posterior tendon, the role of imaging modalities and review treatment methods. PMID:22470798

  14. Therapeutics for tendon regeneration: a multidisciplinary review of tendon research for improved healing.

    PubMed

    Paredes, J J; Andarawis-Puri, Nelly

    2016-11-01

    Tendon injuries, known as tendinopathies, are common musculoskeletal injuries that affect a wide range of the population. Canonical tendon healing is characterized by fibrosis, scar formation, and the loss of tissue mechanical and structural properties. Understanding the regenerative tendon environment is an area of increasing interest in the field of musculoskeletal research. Previous studies have focused on utilizing individual elements from the fields of biomechanics, developmental biology, cell and growth factor therapy, and tissue engineering in an attempt to develop regenerative tendon therapeutics. Still, the specific mechanism for regenerative healing remains unknown. In this review, we highlight some of the current approaches of tendon therapeutics and elucidate the differences along the tendon midsubstance and enthesis, exhibiting the necessity of location-specific tendon therapeutics. Furthermore, we emphasize the necessity of further interdisciplinary research in order to reach the desired goal of fully understanding the mechanisms underlying regenerative healing.

  15. Duplication of the extensor carpi ulnaris tendon.

    PubMed

    Barfred, T; Adamsen, S

    1986-05-01

    Three cases are presented, in which an anomalous tendon slip between the extensor carpi ulnaris tendon and the extensor apparatus of the fifth finger was found. One of the patients was a violinist, who had serious impairment of the left wrist joint and the small finger due to the anomaly. The symptoms disappeared after excision.

  16. Tendon Vasculature in Health and Disease

    PubMed Central

    Tempfer, Herbert; Traweger, Andreas

    2015-01-01

    Tendons represent a bradytrophic tissue which is poorly vascularized and, compared to bone or skin, heal poorly. Usually, a vascularized connective scar tissue with inferior functional properties forms at the injury site. Whether the increased vascularization is the root cause of tissue impairments such as loss of collagen fiber orientation, ectopic formation of bone, fat or cartilage, or is a consequence of these pathological changes remains unclear. This review provides an overview of the role of tendon vasculature in healthy and chronically diseased tendon tissue as well as its relevance for tendon repair. Further, the nature and the role of perivascular tendon stem/progenitor cells residing in the vascular niche will be discussed and compared to multipotent stromal cells in other tissues. PMID:26635616

  17. Structural and biomechanical changes in the Achilles tendon after chronic treatment with statins.

    PubMed

    de Oliveira, L P; Vieira, C P; Guerra, F D; Almeida, M S; Pimentel, E R

    2015-03-01

    Cases of tendinopathy and tendon ruptures have been reported as side effects associated with statin therapy. This work assessed possible changes in the structural and biomechanical properties of the tendons after chronic treatment with statins. Wistar rats were divided into the following groups: treated with atorvastatin (A-20 and A-80), simvastatin (S-20 and S-80) and the group that received no treatment (C). The doses of statins were calculated using allometric scaling, based on the doses of 80 mg/day and 20 mg/day recommended for humans. The morphological aspect of the tendons in A-20, S-20 and S-80 presented signals consistent with degeneration. Both the groups A-80 and S-80 showed a less pronounced metachromasia in the compression region of the tendons. Measurements of birefringence showed that A-20, A-80 and S-80 groups had a lower degree of organization of the collagen fibers. In all of the groups treated with statins, the thickness of the epitenon was thinner when compared to the C group. In the biomechanical tests the tendons of the groups A-20, A-80 and S-20 were less resistant to rupture. Therefore, statins affected the organization of the collagen fibers and decreased the biomechanical strength of the tendons, making them more predisposed to ruptures.

  18. Use of stem cells and growth factors in rotator cuff tendon repair.

    PubMed

    Akyol, Engin; Hindocha, Sandip; Khan, Wasim S

    2015-01-01

    In this review, we analysed the role of stem cell and growth factor therapy on rotator cuff tendon repair. The injury to the rotator cuff tendons can be sustained in numerous ways and generally causes significant pain and disability to the affected individual. Following surgical repair of ruptured rotator cuff tendons re-rupture rates can be as high as 20-60%. In order to augment this repair process and to decrease the re-rupture rates tissue engineering methods can be used. These include the use of stem cells and growth factors. Mesenchymal stem cells are stem cells which can differentiate into a variety of connective tissue cell types and can therefore be utilised in repairing tendons. So far there has only been one human study using stem cells in rotator cuff tendon repair. This study has produced a positive result but consisted of only 14 patients and lacks a control group for comparison. Similar work has also been done using growth factors. Both individual and combination growth factor therapy have been used to improve rotator cuff tendon repair. However, the results so far have been disappointing with growth factors. For the purpose of future studies better techniques should be explored with regards to the delivery of stem cells and growth factors as well as the possibility of combining growth factor and stem cell therapy to improve repair rates.

  19. Ultrasound strain mapping of Achilles tendon compressive strain patterns during dorsiflexion.

    PubMed

    Chimenti, Ruth L; Flemister, A Samuel; Ketz, John; Bucklin, Mary; Buckley, Mark R; Richards, Michael S

    2016-01-04

    Heel lifts are commonly prescribed to patients with Achilles tendinopathy, yet little is known about the effect on tendon compressive strain. The purposes of the current study were to (1) develop a valid and reliable ultrasound elastography technique and algorithm to measure compressive strain of human Achilles tendon in vivo, (2) examine the effects of ankle dorsiflexion (lowering via controlled removal of a heel lift and partial squat) on compressive strain of the Achilles tendon insertion and (3) examine the relative compressive strain between the deep and superficial regions of the Achilles tendon insertion. All tasks started in a position equivalent to standing with a 30mm heel lift. An ultrasound transducer positioned over the Achilles tendon insertion was used to capture radiofrequency images. A non-rigid image registration-based algorithm was used to estimate compressive strain of the tendon, which was divided into 2 regions (superficial, deep). The bland-Altman test and intraclass correlation coefficient were used to test validity and reliability. One-way repeated measures ANOVA was used to compare compressive strain between regions and across tasks. Compressive strain was accurately and reliably (ICC>0.75) quantified. There was greater compressive strain during the combined task of lowering and partial squat compared to the lowering (P=.001) and partial squat (P<.001) tasks separately. There was greater compressive strain in the deep region of the tendon compared to the superficial for all tasks (P=.001). While these findings need to be examined in a pathological population, heel lifts may reduce tendon compressive strain during daily activities.

  20. Strain and elongation of the vastus lateralis aponeurosis and tendon in vivo during maximal isometric contraction.

    PubMed

    Stafilidis, Savvas; Karamanidis, Kiros; Morey-Klapsing, Gaspar; Demonte, Gianpiero; Brüggemann, Gert-Peter; Arampatzis, Adamantios

    2005-06-01

    The strain and elongation of the vastus lateralis (VL) tendon, tendon plus aponeurosis, and aponeurosis were examined during maximal voluntary contractions on a Biodex-dynamometer (knee angle 115 degrees , hip angle 140 degrees ) in 12 sprinters. Following a warm-up phase, the subjects were instructed to perform a gradual maximal knee extension and hold it for about 3 s. The kinematics of the leg were recorded using a Vicon 512 system with eight cameras operating at 120 Hz. Ultrasonography images were taken simultaneously from the VL myotendinous junction and the mid lateral part of the VL muscle belly. During the maximal isometric knee extensions, the knee joint rotated (13.6+/-5.9 degrees ), leading to an overestimation of the elongation of the tendinous tissues. After correcting for this, the maximal elongation of the VL tendon examined at the myotendinous junction was lower (P<0.05) than the maximal elongation of the VL tendon plus aponeurosis examined at the muscle belly (15 vs. 27 mm, respectively). The maximal estimated strains of the tendon, tendon plus aponeurosis, and aponeurosis showed no statistical differences (8+/-2%, 8+/-1%, and 7+/-2%, respectively, P>0.05). It is concluded that the strains of the human VL tendon, VL tendon plus aponeurosis, and VL aponeurosis, as estimated in vivo by two dimensional ultrasound during maximal isometric contractions, do not differ from each other. The displacement measured at a cross point in the VL muscle belly is significantly greater than that measured at the VL myotendinous junction.

  1. Anterior Cruciate Ligament Reconstruction: Clinical Outcomes of Patella Tendon and Hamstring Tendon Grafts

    PubMed Central

    Gulick, Dawn T.; Yoder, Heather N.

    2002-01-01

    An injury to the ACL can result in significant functional impairment. It has been estimated that more than 100,000 new ACL injuries occur each year. Surgeons employ numerous techniques for reconstruction of the ACL. Of critical importance is the source of the graft to replace the damaged ACL. The graft choices include autografts (the patient's own tissue), allografts (donor tendon), and synthetic/prosthetic ligaments. Tissue harvest sites for autografting include the middle third of the patella tendon, the quadriceps tendon, semitendinosus tendon, gracilis tendon, iliotibial band, tensor fascia lata, and the Achilles tendon. Selection of the type of graft material is predicated upon the tissue's ability to tolerate high levels of stress. Likewise, the clinical presentation and functional outcome is related to the graft material selected. This manuscript specifically examined the patella tendon and hamstring tendon grafts. Numerous manuscripts that studied the outcomes of these graft materials were compiled to help the clinician appreciate the advantages and disadvantages of each of the graft materials. Outcome measures such as thigh circumference, knee range of motion, isokinetic strength, knee stability, pain, and vertical jump/1-leg hop were incorporated. The purpose of this manuscript was to compare and contrast the clinical presentation of patients who underwent an ACL reconstruction using the patella tendon versus the hamstring tendons. This information can be valuable to the clinician when considering the rehabilitation protocol after ACL reconstruction. PMID:24701126

  2. Is higher serum cholesterol associated with altered tendon structure or tendon pain? A systematic review

    PubMed Central

    Tilley, Benjamin J; Cook, Jill L; Docking, Sean I; Gaida, James E

    2015-01-01

    Background Tendon pain occurs in individuals with extreme cholesterol levels (familial hypercholesterolaemia). It is unclear whether the association with tendon pain is strong with less extreme elevations of cholesterol. Objective To determine whether lipid levels are associated with abnormal tendon structure or the presence of tendon pain. Methods We conducted a systematic review and meta-analysis. Relevant articles were found through an electronic search of 6 medical databases—MEDLINE, Cochrane, AMED, EMBASE, Web of Science and Scopus. We included all case–control or cross-sectional studies with data describing (1) lipid levels or use of lipid-lowering drugs and (2) tendon structure or tendon pain. Results 17 studies (2612 participants) were eligible for inclusion in the review. People with altered tendon structure or tendon pain had significantly higher total cholesterol, low-density lipoprotein cholesterol and triglycerides, as well as lower high-density lipoprotein cholesterol; with mean difference values of 0.66, 1.00, 0.33, and −0.19 mmol/L, respectively. Conclusions The results of this review indicate that a relationship exists between an individual’s lipid profile and tendon health. However, further longitudinal studies are required to determine whether a cause and effect relationship exists between tendon structure and lipid levels. This could lead to advancement in the understanding of the pathoaetiology and thus treatment of tendinopathy. PMID:26474596

  3. Regeneration of Full-Thickness Rotator Cuff Tendon Tear After Ultrasound-Guided Injection With Umbilical Cord Blood-Derived Mesenchymal Stem Cells in a Rabbit Model

    PubMed Central

    Park, Gi-Young; Lee, Sang Chul

    2015-01-01

    Rotator cuff tendon tear is one of the most common causes of chronic shoulder pain and disability. In this study, we investigated the therapeutic effects of ultrasound-guided human umbilical cord blood (UCB)-derived mesenchymal stem cell (MSC) injection to regenerate a full-thickness subscapularis tendon tear in a rabbit model by evaluating the gross morphology and histology of the injected tendon and motion analysis of the rabbit’s activity. At 4 weeks after ultrasound-guided UCB-derived MSC injection, 7 of the 10 full-thickness subscapularis tendon tears were only partial-thickness tears, and 3 remained full-thickness tendon tears. The tendon tear size and walking capacity at 4 weeks after UCB-derived MSC injection under ultrasound guidance were significantly improved compared with the same parameters immediately after tendon tear. UCB-derived MSC injection under ultrasound guidance without surgical repair or bioscaffold resulted in the partial healing of full-thickness rotator cuff tendon tears in a rabbit model. Histology revealed that UCB-derived MSCs induced regeneration of rotator cuff tendon tear and that the regenerated tissue was predominantly composed of type I collagens. In this study, ultrasound-guided injection of human UCB-derived MSCs contributed to regeneration of the full-thickness rotator cuff tendon tear without surgical repair. The results demonstrate the effectiveness of local injection of MSCs into the rotator cuff tendon. Significance The results of this study suggest that ultrasound-guided umbilical cord blood-derived mesenchymal stem cell injection may be a useful conservative treatment for full-thickness rotator cuff tendon tear repair. PMID:26371340

  4. Biological Augmentation of Rotator Cuff Tendon Repair

    PubMed Central

    Kovacevic, David

    2008-01-01

    A histologically normal insertion site does not regenerate following rotator cuff tendon-to-bone repair, which is likely due to abnormal or insufficient gene expression and/or cell differentiation at the repair site. Techniques to manipulate the biologic events following tendon repair may improve healing. We used a sheep infraspinatus repair model to evaluate the effect of osteoinductive growth factors and BMP-12 on tendon-to-bone healing. Magnetic resonance imaging and histology showed increased formation of new bone and fibrocartilage at the healing tendon attachment site in the treated animals, and biomechanical testing showed improved load-to-failure. Other techniques with potential to augment repair site biology include use of platelets isolated from autologous blood to deliver growth factors to a tendon repair site. Modalities that improve local vascularity, such as pulsed ultrasound, have the potential to augment rotator cuff healing. Important information about the biology of tendon healing can also be gained from studies of substances that inhibit healing, such as nicotine and antiinflammatory medications. Future approaches may include the use of stem cells and transcription factors to induce formation of the native tendon-bone insertion site after rotator cuff repair surgery. PMID:18264850

  5. Distal biceps tendon injuries: diagnosis and management.

    PubMed

    Ramsey, M L

    1999-01-01

    Rupture of the distal biceps tendon occurs most commonly in the dominant extremity of men between 40 and 60 years of age when an unexpected extension force is applied to the flexed arm. Although previously thought to be an uncommon injury, distal biceps tendon ruptures are being reported with increasing frequency. The rupture typically occurs at the tendon insertion into the radial tuberosity in an area of preexisting tendon degeneration. The diagnosis is made on the basis of a history of a painful, tearing sensation in the antecubital region. Physical examination demonstrates a palpable and visible deformity of the distal biceps muscle belly with weakness in flexion and supination. The ability to palpate the tendon in the antecubital fossa may indicate partial tearing of the biceps tendon. Plain radiographs may show hypertrophic bone formation at the radial tuberosity. Magnetic resonance imaging is generally not required to diagnose a complete rupture but may be useful in the case of a partial rupture. Early surgical reattachment to the radial tuberosity is recommended for optimal results. A modified two-incision technique is the most widely used method of repair, but anterior single-incision techniques may be equally effective provided the radial nerve is protected. The patient with a chronic rupture may benefit from surgical reattachment, but proximal retraction and scarring of the muscle belly can make tendon mobilization difficult, and inadequate length of the distal biceps tendon may necessitate tendon augmentation. Postoperative rehabilitation must emphasize protected return of motion for the first 8 weeks after repair. Formal strengthening may begin as early as 8 weeks, with a return to unrestricted activities, including lifting, by 5 months.

  6. Percutaneous techniques for tendon transfers in the foot and ankle.

    PubMed

    Panchbhavi, Vinod Kumar

    2014-03-01

    Tendon transfer procedures are useful for replacing a dysfunctional or diseased tendon or for restoring muscle imbalance. The tendon to be transferred is harvested as distal as is necessary to provide adequate length for rerouting and attachment at the different site. The harvesting of tendon itself can be attained using an open surgical approach or minimally invasive percutaneous techniques that limit surgical exposure. This article describes percutaneous techniques for tendon transfer procedures used to address foot and ankle disorders.

  7. Tendon injury and tendinopathy: healing and repair.

    PubMed

    Sharma, Pankaj; Maffulli, Nicola

    2005-01-01

    Tendon disorders are frequent and are responsible for substantial morbidity both in sports and in the workplace. Tendinopathy, as opposed to tendinitis or tendinosis, is the best generic descriptive term for the clinical conditions in and around tendons arising from overuse. Tendinopathy is a difficult problem requiring lengthy management, and patients often respond poorly to treatment. Preexisting degeneration has been implicated as a risk factor for acute tendon rupture. Several physical modalities have been developed to treat tendinopathy. There is limited and mixed high-level evidence to support the, albeit common, clinical use of these modalities. Further research and scientific evaluation are required before biological solutions become realistic options.

  8. Fibromatosis of the flexor pollicus longus tendon

    PubMed Central

    Damkat-Thomas, L; Black, CE; Herbert, K

    2010-01-01

    An unusual case of fibromatosis of the dominant left flexor pollicus longus (FPL) in a thirteen year old schoolboy. Initially presenting with pain in the thenar eminence and difficulty flexing the metacarpal phalangeal joint (MPJ), other symptoms include locking, triggering and difficulty writing. MRI showed a 4cm segment of thickened abnormal tendon. Intra-operatively three 1cm nodules were excised from the FPL while preserving the tendon. Histopathology reported the nodules as fibromatosis. A literature search revealed that this has not previously been reported although symptomatic tendon sheath fibromas have. Our patient achieved a good result following surgical intervention and the two year review has shown no complications. PMID:24946359

  9. A review of work on artificial tendons.

    PubMed

    Murray, G A; Semple, J C

    1979-07-01

    Work done to date on artificial tendons by many authors is described in chronological order. A brief description of the techniques and materials is given in each case, with a summary of the results. The overall implications of the work are discussed in terms of prosthesis durability, the attachment to bone and tendon, mechanical properties and the volume of scar tissue generated. It is concluded that construction of a permanent artificial tendon is a realistic and worthwhile aim; further experimental work ought to include long term in vivo testing with means provided for monitoring any drift of the attachment points.

  10. Stem Cells for Augmenting Tendon Repair

    PubMed Central

    Gulotta, Lawrence V.; Chaudhury, Salma; Wiznia, Daniel

    2012-01-01

    Tendon healing is fraught with complications such as reruptures and adhesion formation due to the formation of scar tissue at the injury site as opposed to the regeneration of native tissue. Stem cells are an attractive option in developing cell-based therapies to improve tendon healing. However, several questions remain to be answered before stem cells can be used clinically. Specifically, the type of stem cell, the amount of cells, and the proper combination of growth factors or mechanical stimuli to induce differentiation all remain to be seen. This paper outlines the current literature on the use of stem cells for tendon augmentation. PMID:22190960

  11. Ultrasonic stress measurements in prestressing tendons

    NASA Astrophysics Data System (ADS)

    Washer, Glenn A.; Green, Robert E.

    2002-05-01

    The goal of this research was to examine ultrasonic stress measurement techniques for the condition assessment of prestressing tendons. Acoustoelastic measurements were made in prestressing rods and strands, and constants are reported that relate the change in ultrasonic velocity to the change in stress. The effects of dispersion in prestressing tendons, which act as circular wave guides for ultrasonic waves, were measured and evaluated. For this research, narrow-band, noncontact Electromagnetic Acoustic Transducers (EMATs) were designed to launch and receive ultrasonic waves propagating within the tendons.

  12. Proximal Biceps Tendon and Rotator Cuff Tears.

    PubMed

    Virk, Mandeep S; Cole, Brian J

    2016-01-01

    The long head of biceps tendon (LHBT) is frequently involved in rotator cuff tears and can cause anterior shoulder pain. Tendon hypertrophy, hourglass contracture, delamination, tears, and tendon instability in the bicipital groove are common macroscopic pathologic findings affecting the LHBT in the presence of rotator cuff tears. Failure to address LHBT disorders in the setting of rotator cuff tear can result in persistent shoulder pain and poor satisfaction after rotator cuff repair. Tenotomy or tenodesis of the LHBT are effective options for relieving pain arising from the LHBT in the setting of reparable and selected irreparable rotator cuff tears.

  13. Les plaies du tendon patellaire

    PubMed Central

    Mechchat, Atif; Elidrissi, Mohammed; Mardy, Abdelhak; Elayoubi, Abdelghni; Shimi, Mohammed; Elibrahimi, Abdelhalim; Elmrini, Abdelmajid

    2014-01-01

    Les plaies du tendon patellaire sont peu fréquentes et sont peu rapportés dans la littérature, contrairement aux ruptures sous cutanées. Les sections du tendon patellaire nécessitent une réparation immédiate afin de rétablir l'appareil extenseur et de permettre une récupération fonctionnelle précoce. A travers ce travail rétrospectif sur 13 cas, nous analysons les aspects épidémiologiques, thérapeutiques et pronostiques de ce type de pathologie en comparant différents scores. L’âge moyen est de 25 ans avec une prédominance masculine. Les étiologies sont dominées par les accidents de la voie publique (68%) et les agressions par agent tranchant (26%) et contendant (6 %). Tous nos patients ont bénéficié d'un parage chirurgical avec suture tendineuse direct protégée par un laçage au fils d'aciers en légère flexion. La rééducation est débutée après sédation des phénomènes inflammatoires. Au dernier recul les résultats sont excellents et bon à 92%. Nous n'avons pas noté de différence de force musculaire et d'amplitude articulaire entre le genou sain et le genou lésé. Les lésions ouvertes du tendon patellaire est relativement rare. La prise en charge chirurgicale rapide donne des résultats assez satisfaisants. La réparation est généralement renforcée par un semi-tendineux, synthétique ou métallique en forme de cadre de renfort pour faciliter la réadaptation et réduire le risque de récidive après la fin de l'immobilisation. PMID:25170379

  14. Both standing and postural threat decrease Achilles tendon reflex inhibition from tendon electrical stimulation.

    PubMed

    Horslen, Brian C; Inglis, J Timothy; Blouin, Jean-Sébastien; Carpenter, Mark G

    2017-03-22

    Golgi tendon organ Ib reflexes are thought to contribute to standing balance control, but it is unknown if they are modulated when people are exposed to a postural threat. We used a novel application of tendon electrical stimulation (TStim) to elicit Ib inhibitory reflexes in the medial gastrocnemius, while actively engaged in upright standing balance, to examine a) how Ib reflexes to TStim are influenced by upright stance, and b) the effects of height-induced postural threat on Ib reflexes during standing. TStim evoked short-latency (<47 ms) inhibition apparent in trigger-averaged rectified EMG, which was quantified in terms of area, duration, and mean amplitude of inhibition. In order to validate the use of TStim in a standing model, TStim-Ib inhibition was compared from conditions where participants were laying prone vs. standing upright. TStim evoked Ib inhibition in both conditions, however significant reductions in Ib inhibition area (42.2%) and duration (32.9%) were observed during stance. Postural threat, manipulated by having participants stand at LOW (0.8 m high, 0.6 m from edge) and HIGH (3.2 m, at edge) elevated surfaces, significantly reduced Ib inhibition area (32.4%), duration (16.4%) and amplitude (24.8%) in the HIGH, compared to LOW threat condition. These results demonstrate TStim is a viable technique for investigating Ib reflexes in standing, and confirm Ib reflexes are modulated with postural orientation. The novel observation of reduced Ib inhibition with elevated postural threat reveals that human Ib reflexes are context-dependent, and the human Ib reflex pathways are modulated by threat or emotional processing centres of the CNS. This article is protected by copyright. All rights reserved.

  15. Famotidine suppresses osteogenic differentiation of tendon cells in vitro and pathological calcification of tendon in vivo.

    PubMed

    Yamamoto, Kenichi; Hojo, Hironori; Koshima, Isao; Chung, Ung-il; Ohba, Shinsuke

    2012-12-01

    Heterotopic ossification or calcification follows any type of musculoskeletal trauma and is known to occur after arthroplasties of hip, knee, shoulder, or elbow; fractures; joint dislocations; or tendon ruptures. Histamine receptor H2 (Hrh2) has been shown to be effective for reducing pain and decreasing calcification in patients with calcifying tendinitis, which suggested that H2 blockers were effective for the treatment of tendon ossification or calcification. However, the detailed mechanisms of its action on tendon remain to be clarified. We investigated the mechanisms underlying H2 blocker-mediated suppression of tendon calcification, with a focus on the direct action of the drug on tendon cells. Famotidine treatment suppressed the mRNA expressions of Col10a1 and osteocalcin, ossification markers, in a tendon-derived cell line TT-D6, as well as a preosteoblastic one MC3T3-E1. Both of the cell lines expressed Hrh2; histamine treatment induced osteocalcin expression in these cells. Famotidine administration suppressed calcification in the Achilles tendon of ttw mice, a mouse model of ectopic ossification. These data suggest that famotidine inhibits osteogenic differentiation of tendon cells in vitro, and this inhibition may underlie the anti-calcification effects of the drug in vivo. This study points to the use of H2 blockers as a promising strategy for treating heterotopic ossification or calcification in tendon, and provides evidence in support of the clinical use of famotidine.

  16. Assessment of Postoperative Tendon Quality in Patients With Achilles Tendon Rupture Using Diffusion Tensor Imaging and Tendon Fiber Tracking.

    PubMed

    Sarman, Hakan; Atmaca, Halil; Cakir, Ozgur; Muezzinoglu, Umit Sefa; Anik, Yonca; Memisoglu, Kaya; Baran, Tuncay; Isik, Cengiz

    2015-01-01

    Although pre- and postoperative imaging of Achilles tendon rupture (ATR) has been well documented, radiographic evaluations of postoperative intratendinous healing and microstructure are still lacking. Diffusion tensor imaging (DTI) is an innovative technique that offers a noninvasive method for describing the microstructure characteristics and organization of tissues. DTI was used in the present study for quantitative assessment of fiber continuity postoperatively in patients with acute ATR. The data from 16 patients with ATR from 2005 to 2012 were retrospectively analyzed. The microstructure of ART was evaluated using tendon fiber tracking, tendon continuity, fractional anisotropy, and apparent diffusion coefficient values by way of DTI. The distal and proximal portions were measured separately in both the ruptured and the healthy extremities of each patient. The mean patient age was 41.56 ± 8.49 (range 26 to 56) years. The median duration of follow-up was 21 (range 6 to 80) months. The tendon fractional anisotropy values of the ruptured Achilles tendon were significantly lower statistically than those of the normal side (p = .001). However, none of the differences between the 2 groups with respect to the distal and proximal apparent diffusion coefficient were statistically significant (p = .358 and p = .899, respectively). In addition, the fractional anisotropy and apparent diffusion coefficient measurements were not significantly different in the proximal and distal regions of the ruptured tendons compared with the healthy tendons. The present study used DTI and fiber tracking to demonstrate the radiologic properties of postoperative Achilles tendons with respect to trajectory and tendinous fiber continuity. Quantifying DTI and fiber tractography offers an innovative and effective tool that might be able to detect microstructural abnormalities not appreciable using conventional radiologic techniques.

  17. Traumatic tibialis anterior tendon rupture: treatment with a two-stage silicone tube and an interposition hamstring tendons graft protocol.

    PubMed

    Kontogeorgakos, Vasileios; Koutalos, Antonios; Hantes, Michael; Manoudis, Gregory; Badras, Leonidas; Malizos, Konstantinos

    2015-03-01

    A novel technique for managing ruptured tibialis anterior tendon complicated by infection and tendon substance loss in a young adult is described. A two-stage reconstruction technique with a silicon tube and tendon autograft was performed. At first, after local control of the infection, scar excision and placement of a silicone tube was performed. Ten weeks later, ipsilateral hamstrings tendons were harvested and bridged the 7 cm tendon gap. Eighteen months later, the patient has excellent clinical and functional outcome.

  18. [Tendon ruptures of the shoulder].

    PubMed

    Habermeyer, P

    1989-08-01

    Common sports, involving raising the arms above the head, i.e., throwing, racquet games and swimming, often result in rotator cuff tendinitis. During the throwing motion, the humeral head and its overlying biceps tendon and rotator cuff must pass rapidly under the coraco-acromial arch. Damage to these structures can occur by several mechanism. First, an increase in the size of the structures passing underneath the arch may lead to impingement. This can occur either by way of hypertrophy of the musculotendinous cuff or by way of inflammation of the cuff. Second, a decreased space available underneath the arch secondary to osteophyte formation of the acromion and fibrosis of the subacromial space may lead to impingement. Third, weakness or incompetence of the rotator cuff allows the humerus to ride up and impinge on the coracoacromial arch with motion of the shoulder. Tendinitis can be combined with increased laxity of the glenohumeral joint and/or acquired instability due to a labral tear. Prevention of overuse injuries is a cornerstone of our treatment concept. The muscle tendon unit requires passive and neuromuscular facilitated streching after warming-up exercises. Muscular imbalance and weakness are prevented by balanced eccentric strenthening with particular attention to the external rotators and scapular muscles. Knowledge of the mechanics of the pitching motion, tennis serve, swimming stroke, etc. is of paramount importance in the prevention of injuries. As the onset of shoulder problems contributes to a particularly fatiguing situation, extreme fatique performance severity should be avoided. Every effort must be made to apply conservative treatment when overuse problems arise in the athlete's shoulder.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. The Effect of Corticosteroid on Collagen Expression in Injured Rotator Cuff Tendon

    PubMed Central

    Wei, Anthony S.; Callaci, John J.; Juknelis, Dainius; Marra, Guido; Tonino, Pietro; Freedman, Kevin B.; Wezeman, Frederick H.

    2011-01-01

    Background Subacromial corticosteroid injections are commonly used in the nonoperative management of rotator cuff disease. The effects of corticosteroid injection on injured rotator cuff tendons have not been studied. Our aims were to characterize the acute response of rotator cuff tendons to injury through the analysis of the type-III to type-I collagen expression ratio, a tendon injury marker, and to examine the effects of corticosteroid on this response. Methods Sixty Sprague-Dawley rats were randomly assigned to four groups: control, tendon injury, steroid treatment, and tendon injury and steroid treatment. Six rats served as sham controls. Unilateral tendon injuries were created with full-thickness defects across 50% of the total width of the infraspinatus tendon, 5 mm from its humeral insertion. Steroid treatment with a single dose of methylprednisolone (0.6 mg/kg), equivalent to that given to humans, was injected into the subacromial space under direct visualization. Steroid treatment followed the creation of an injury in the rats in the injury and steroid treatment group. At one, three, and five weeks after the injury, the total RNA isolated from tendons was quantified with real-time polymerase chain reaction with use of primers for type-I and type-III collagen and ribosomal 18s RNA. Results The type-III to type-I collagen expression ratio remained at baseline at all time-points in the control and sham groups. At one week, the type-III to type-I collagen expression ratio increased more than fourfold above the control level in the tendon injury group (p = 0.017) and the tendon injury and steroid treatment group (p = 0.003). The ratio remained greater than twofold above the control at three weeks in both groups (p = 0.003 and p = 0.037) and returned to baseline at five weeks. Interestingly, the group that had steroid treatment only showed an increase of >4.5-fold (p = 0.001) in the type-III to type-I collagen expression ratio, without structural injury to the

  20. Position Control of Tendon-Driven Fingers

    NASA Technical Reports Server (NTRS)

    Abdallah, Muhammad E.; Platt, Robert, Jr.; Hargrave, B.; Pementer, Frank

    2011-01-01

    Conventionally, tendon-driven manipulators implement some force control scheme based on tension feedback. This feedback allows the system to ensure that the tendons are maintained taut with proper levels of tensioning at all times. Occasionally, whether it is due to the lack of tension feedback or the inability to implement sufficiently high stiffnesses, a position control scheme is needed. This work compares three position controllers for tendon-driven manipulators. A new controller is introduced that achieves the best overall performance with regards to speed, accuracy, and transient behavior. To compensate for the lack of tension feedback, the controller nominally maintains the internal tension on the tendons by implementing a two-tier architecture with a range-space constraint. These control laws are validated experimentally on the Robonaut-2 humanoid hand. I

  1. Flexor tendon repair in zone III.

    PubMed

    Al-Qattan, Mohammad M

    2011-01-01

    There is a paucity of the literature on the outcome of zone III flexor tendon injuries. In this paper, we report on the results of zone III flexor tendon repair in 35 consecutive adult patients with clean cut lacerations of both flexor tendons in 42 fingers. There were 25 men and 10 women with an average age of 32 years. Repair of both flexor tendons was performed using 'figure of eight' core sutures and a continuous epitendinous suture. Postoperatively, an immediate active range of motion protocol was applied to ensure full active extension of the interphalangeal joints. The results were assessed using the Strickland-Glogovac grading system. There were no ruptures. One patient with two injured fingers developed complex regional pain syndrome and the final outcome was fair in both fingers. In the remaining 34 patients (40 fingers), 33 patients (38 fingers) had an excellent outcome and the remaining patient (two fingers) had a good outcome.

  2. Glycosaminoglycans in Tendon Physiology, Pathophysiology, and Therapy.

    PubMed

    Ryan, Christina N M; Sorushanova, Anna; Lomas, Alex J; Mullen, Anne Maria; Pandit, Abhay; Zeugolis, Dimitrios I

    2015-07-15

    Although glycosaminoglycans constitute a minor portion of native tissues, they play a crucial role in various physiological processes, while their abnormal expression is associated with numerous pathophysiologies. Glycosaminoglycans have become increasingly prevalent in biomaterial design for tendon repair, given their low immunogenicity and their inherent capacity to stimulate the regenerative processes, while maintaining resident cell phenotype and function. Further, their incorporation into three-dimensional scaffold conformations significantly improves their mechanical properties, while reducing the formation of peritendinous adhesions. Herein, we discuss the role of glycosaminoglycans in tendon physiology and pathophysiology and the advancements achieved to date using glycosaminoglycan-functionalized scaffolds for tendon repair and regeneration. It is evidenced that glycosaminoglycan functionalization has led to many improvements in tendon tissue engineering and it is anticipated to play a pivotal role in future reparative therapies.

  3. Direct E-jet printing of three-dimensional fibrous scaffold for tendon tissue engineering.

    PubMed

    Wu, Yang; Wang, Zuyong; Ying Hsi Fuh, Jerry; San Wong, Yoke; Wang, Wilson; San Thian, Eng

    2017-04-01

    Tissue engineering (TE) offers a promising strategy to restore diseased tendon tissue. However, a suitable scaffold for tendon TE has not been achieved with current fabrication techniques. Herein, we report the development of a novel electrohydrodynamic jet printing (E-jetting) for engineering 3D tendon scaffold with high porosity and orientated micrometer-size fibers. The E-jetted scaffold comprised tubular multilayered micrometer-size fibrous bundles, with interconnected spacing and geometric anisotropy along the longitudinal direction of the scaffold. Fiber diameter, stacking pattern, and interfiber distance have been observed to affect the structural stability of the scaffold, of which the enhanced mechanical strength can be obtained for scaffolds with thick fibers as the supporting layer. Human tenocytes showed a significant increase in cellular metabolism on the E-jetted scaffolds as compared to that on conventional electrospun scaffolds (2.7-, 2.8-, and 3.1-fold increase for 150, 300, and 600 µm interfiber distance, respectively; p < 0.05). Furthermore, the scaffolds provided structural support for human tenocytes to align with controlled orientation along the longitudinal direction of the scaffold, and promoted the expression of collagen type I. For the first time, E-jetting has been explored as a novel scaffolding approach for tendon TE, and offers a 3D fibrous scaffold to promote organized tissue reconstruction for potential tendon healing. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 616-627, 2017.

  4. The effect of screw insertion torque on tendons fixed with spiked washers.

    PubMed

    Beynnon, B D; Meriam, C M; Ryder, S H; Fleming, B C; Johnson, R J

    1998-01-01

    The long-term success of a hamstring tendon graft depends not only on the type of device that is used for fixation but also on the mechanical interlocking of the soft tissue between the fixation device and bone. The purpose of this study was to evaluate the effect of screw insertion torque on the structural properties of soft tissue fixed to bone with a spiked metal washer. Two bovine tendons, one similar in size to a human semitendinosus tendon and the other similar in size to a human gracilis tendon, were secured to a bovine femur using a figure-of-8 technique with screws and metal spiked washers. A single load to failure was applied at 25 mm/sec. A significant positive linear correlation was observed between fixation screw insertion torque magnitude and the ultimate failure load value. An increase in the fixation screw insertion torque produced an increase in the ultimate failure load value. Similarly, there was a significant positive linear correlation between fixation screw insertion torque magnitude and the average maximum linear load value. No relationship was detected between screw insertion torque magnitude and the linear stiffness values of the tendon-fixation construct, indicating that a reproducible model was used. This study demonstrates that screw insertion torque is an important variable that controls the initial strength of soft tissue fixation to bone.

  5. Lipoma arborescens of the biceps tendon sheath.

    PubMed

    White, Eric A; Omid, Reza; Matcuk, George R; Domzalski, Jerome T; Fedenko, Alexander N; Gottsegen, Christopher J; Forrester, Deborah M; Patel, Dakshesh B

    2013-10-01

    Lipoma arborescens, described as lipomatous infiltration and distention of synovial villi resulting in a frond-like appearance, most frequently affects the suprapatellar recess of the knee. While there have been reports of this entity involving the upper extremity joints, bursa, and tendon sheaths, we present the first reported case of lipoma arborescens isolated to the biceps tendon sheath. We describe imaging and histologic findings with clinical correlation.

  6. Grasp Assist Device with Shared Tendon Actuator Assembly

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Bergelin, Bryan J. (Inventor); Bridgwater, Lyndon (Inventor)

    2015-01-01

    A grasp assist device includes a glove with first and second tendon-driven fingers, a tendon, and a sleeve with a shared tendon actuator assembly. Tendon ends are connected to the respective first and second fingers. The actuator assembly includes a drive assembly having a drive axis and a tendon hook. The tendon hook, which defines an arcuate surface slot, is linearly translatable along the drive axis via the drive assembly, e.g., a servo motor thereof. The flexible tendon is routed through the surface slot such that the surface slot divides the flexible tendon into two portions each terminating in a respective one of the first and second ends. The drive assembly may include a ball screw and nut. An end cap of the actuator assembly may define two channels through which the respective tendon portions pass. The servo motor may be positioned off-axis with respect to the drive axis.

  7. Tension Distribution in a Tendon-Driven Robotic Finger

    NASA Technical Reports Server (NTRS)

    Abdallah, Muhammad E. (Inventor); Platt, Robert (Inventor); Wampler, II, Charles W. (Inventor)

    2013-01-01

    A method is provided for distributing tension among tendons of a tendon-driven finger in a robotic system, wherein the finger characterized by n degrees of freedom and n+1 tendons. The method includes determining a maximum functional tension and a minimum functional tension of each tendon of the finger, and then using a controller to distribute tension among the tendons, such that each tendon is assigned a tension value less than the maximum functional tension and greater than or equal to the minimum functional tension. The method satisfies the minimum functional tension while minimizing the internal tension in the robotic system, and satisfies the maximum functional tension without introducing a coupled disturbance to the joint torques. A robotic system includes a robot having at least one tendon-driven finger characterized by n degrees of freedom and n+1 tendons, and a controller having an algorithm for controlling the tendons as set forth above.

  8. Laminar Tendon Composites with Enhanced Mechanical Properties

    PubMed Central

    Alberti, Kyle A.; Sun, Jeong-Yun; Illeperuma, Widusha R.; Suo, Zhigang; Xu, Qiaobing

    2015-01-01

    Purpose A strong isotropic material that is both biocompatible and biodegradable is desired for many biomedical applications, including rotator cuff repair, tendon and ligament repair, vascular grafting, among others. Recently, we developed a technique, called “bioskiving” to create novel 2D and 3D constructs from decellularized tendon, using a combination of mechanical sectioning, and layered stacking and rolling. The unidirectionally aligned collagen nanofibers (derived from sections of decellularized tendon) offer good mechanical properties to the constructs compared with those fabricated from reconstituted collagen. Methods In this paper, we studied the effect that several variables have on the mechanical properties of structures fabricated from tendon slices, including crosslinking density and the orientation in which the fibers are stacked. Results We observed that following stacking and crosslinking, the strength of the constructs is significantly improved, with crosslinked sections having an ultimate tens ile strength over 20 times greater than non-crosslinked samples, and a modulus nearly 50 times higher. The mechanism of the mechanical failure mode of the tendon constructs with or without crosslinking was also investigated. Conclusions The strength and fiber organization, combined with the ability to introduce transversely isotropic mechanical properties makes the laminar tendon composites a biocompatiable material that may find future use in a number of biomedical and tissue engineering applications. PMID:25691802

  9. The cell biology of suturing tendons

    PubMed Central

    Wong, J.K.F.; Alyouha, S.; Kadler, K.E.; Ferguson, M.W.J.; McGrouther, D.A.

    2010-01-01

    Trauma by suturing tendon form areas devoid of cells termed “acellular zones” in the matrix. This study aimed to characterise the cellular insult of suturing and acellular zone formation in mouse tendon. Acellular zone formation was evaluated using single grasping sutures placed using flexor tendons with time lapse cell viability imaging for a period of 12 h. Both tension and injury were required to induce cell death and cell movement in the formation of the acellular zone. DNA fragmentation studies and transmission electron microscopy indicated that cells necrosed. Parallel in vivo studies showed that cell-to-cell contacts were disrupted following grasping by the suture in tensioned tendon. Without tension, cell death was lessened and cell-to-cell contacts remained intact. Quantitative immunohistochemistry and 3D cellular profile mapping of wound healing markers over a one year time course showed that acellular zones arise rapidly and showed no evidence of healing whilst the wound healing response occurred in the surrounding tissues. The acellular zones were also evident in a standard modified “Kessler” clinical repair. In conclusion, the suture repair of injured tendons produces acellular zones, which may potentially cause early tendon failure. PMID:20600895

  10. Adding Stiffness to the Foot Modulates Soleus Force-Velocity Behaviour during Human Walking

    PubMed Central

    Takahashi, Kota Z.; Gross, Michael T.; van Werkhoven, Herman; Piazza, Stephen J.; Sawicki, Gregory S.

    2016-01-01

    Previous studies of human locomotion indicate that foot and ankle structures can interact in complex ways. The structure of the foot defines the input and output lever arms that influences the force-generating capacity of the ankle plantar flexors during push-off. At the same time, deformation of the foot may dissipate some of the mechanical energy generated by the plantar flexors during push-off. We investigated this foot-ankle interplay during walking by adding stiffness to the foot through shoes and insoles, and characterized the resulting changes in in vivo soleus muscle-tendon mechanics using ultrasonography. Added stiffness decreased energy dissipation at the foot (p < 0.001) and increased the gear ratio (i.e., ratio of ground reaction force and plantar flexor muscle lever arms) (p < 0.001). Added foot stiffness also altered soleus muscle behaviour, leading to greater peak force (p < 0.001) and reduced fascicle shortening speed (p < 0.001). Despite this shift in force-velocity behaviour, the whole-body metabolic cost during walking increased with added foot stiffness (p < 0.001). This increased metabolic cost is likely due to the added force demand on the plantar flexors, as walking on a more rigid foot/shoe surface compromises the plantar flexors’ mechanical advantage. PMID:27417976

  11. Adding Stiffness to the Foot Modulates Soleus Force-Velocity Behaviour during Human Walking

    NASA Astrophysics Data System (ADS)

    Takahashi, Kota Z.; Gross, Michael T.; van Werkhoven, Herman; Piazza, Stephen J.; Sawicki, Gregory S.

    2016-07-01

    Previous studies of human locomotion indicate that foot and ankle structures can interact in complex ways. The structure of the foot defines the input and output lever arms that influences the force-generating capacity of the ankle plantar flexors during push-off. At the same time, deformation of the foot may dissipate some of the mechanical energy generated by the plantar flexors during push-off. We investigated this foot-ankle interplay during walking by adding stiffness to the foot through shoes and insoles, and characterized the resulting changes in in vivo soleus muscle-tendon mechanics using ultrasonography. Added stiffness decreased energy dissipation at the foot (p < 0.001) and increased the gear ratio (i.e., ratio of ground reaction force and plantar flexor muscle lever arms) (p < 0.001). Added foot stiffness also altered soleus muscle behaviour, leading to greater peak force (p < 0.001) and reduced fascicle shortening speed (p < 0.001). Despite this shift in force-velocity behaviour, the whole-body metabolic cost during walking increased with added foot stiffness (p < 0.001). This increased metabolic cost is likely due to the added force demand on the plantar flexors, as walking on a more rigid foot/shoe surface compromises the plantar flexors’ mechanical advantage.

  12. Effects of isotretinoin treatment on cartilage and tendon thicknesses: an ultrasonographic study.

    PubMed

    Yıldızgören, Mustafa Turgut; Karataş Toğral, Arzu; Baki, Ali Erdem; Ekiz, Timur

    2015-07-01

    Effects of retinoic acid on collagen synthesis and cartilage have previously been shown. However, its effects on cartilage and tendons in humans have not been studied yet. Therefore, in order to provide a morphologic insight, the aim of this study was to measure femoral cartilage, Achilles and supraspinatus tendon thicknesses in patients under systemic isotretinoin treatment by using ultrasound. Fifteen patients (nine F, six M) who used isotretinoin for their acnes were included. All patients were treated with isotretinoin 0.5 mg/kg/day for the first month, and the dosage was escalated up to 1 mg/kg/day thereafter. Distal femoral cartilage, supraspinatus, and Achilles tendons thicknesses have been evaluated both before the treatment and at the end of the third month. Femoral cartilage thicknesses were assessed from three midpoints bilaterally; medial condyle, lateral condyle, and intercondylar area. Short/long-axis diameters and cross-sectional area of the Achilles tendons and axial tendon thicknesses of supraspinatus tendon were evaluated from the nondominant side. The mean age of the patients was 20.1 ± 4.9 years, and body mass index was 21.7 ± 2.5 kg/m(2). Although posttreatment cartilage measurements of 30 knees were lower for the three midpoints, it reached significance only for lateral condyle (p = 0.05). In addition, posttreatment tendon measurements were not statistically significant compared with pretreatment values (all p > 0.05). Systemic isotretinoin treatment seems to make cartilage thinner. Further studies considering histological and molecular evaluations with more sample sizes are awaited.

  13. Application of stem cells derived from the periodontal ligament or gingival tissue sources for tendon tissue regeneration

    PubMed Central

    Moshaverinia, Alireza; Xu, Xingtian; Chen, Chider; Ansari, Sahar; Zadeh, Homayoun H.; Snead, Malcolm L.; Shi, Songtao

    2014-01-01

    Tendon injuries are often associated with significant dysfunction and disability due to tendinous tissue’s very limited self-repair capacity and propensity for scar formation. Dental-derived mesenchymal stem cells (MSCs) in combination with appropriate scaffold material present an alternative therapeutic option for tendon repair/regeneration that may be advantageous compared to other current treatment modalities. The MSC delivery vehicle is the principal determinant for successful implementation of MSC-mediated regenerative therapies. In the current study, a co-delivery system based on TGF-β3-loaded RGD-coupled alginate microspheres was developed for encapsulating periodontal ligament stem cells (PDLSCs) or gingival mesenchymal stem cells (GMSCs). The capacity of encapsulated dental MSCs to differentiate into tendon tissue was investigated in vitro and in vivo. Encapsulated dental-derived MSCs were transplanted subcutaneously into immunocompromised mice. Our results revealed that after 4 weeks of differentiation in vitro, PDLSCs and GMSCs as well as the positive control human bone marrow mesenchymal stem cells (hBMMSCs) exhibited high levels of mRNA expression for gene markers related to tendon regeneration (Scx, DCn, Tnmd, and Bgy) via qPCR measurement. In a corresponding in vivo animal model, ectopic neo-tendon regeneration was observed in subcutaneous transplanted MSC-alginate constructs, as confirmed by histological and immunohistochemical staining for protein markers specific for tendons. Interestingly, in our quantitative PCR and in vivo histomorphometric analyses, PDLSCs showed significantly greater capacity for tendon regeneration than GMSCs or hBMMSCs (P<0.05). Altogether, these findings indicate that periodontal ligament and gingival tissues can be considered as suitable stem cell sources for tendon engineering. PDLSCs and GMSCs encapsulated in TGF-β3-loaded RGD-modified alginate microspheres are promising candidates for tendon regeneration. PMID

  14. Application of stem cells derived from the periodontal ligament or gingival tissue sources for tendon tissue regeneration.

    PubMed

    Moshaverinia, Alireza; Xu, Xingtian; Chen, Chider; Ansari, Sahar; Zadeh, Homayoun H; Snead, Malcolm L; Shi, Songtao

    2014-03-01

    Tendon injuries are often associated with significant dysfunction and disability due to tendinous tissue's very limited self-repair capacity and propensity for scar formation. Dental-derived mesenchymal stem cells (MSCs) in combination with appropriate scaffold material present an alternative therapeutic option for tendon repair/regeneration that may be advantageous compared to other current treatment modalities. The MSC delivery vehicle is the principal determinant for successful implementation of MSC-mediated regenerative therapies. In the current study, a co-delivery system based on TGF-β3-loaded RGD-coupled alginate microspheres was developed for encapsulating periodontal ligament stem cells (PDLSCs) or gingival mesenchymal stem cells (GMSCs). The capacity of encapsulated dental MSCs to differentiate into tendon tissue was investigated in vitro and in vivo. Encapsulated dental-derived MSCs were transplanted subcutaneously into immunocompromised mice. Our results revealed that after 4 weeks of differentiation in vitro, PDLSCs and GMSCs as well as the positive control human bone marrow mesenchymal stem cells (hBMMSCs) exhibited high levels of mRNA expression for gene markers related to tendon regeneration (Scx, DCn, Tnmd, and Bgy) via qPCR measurement. In a corresponding in vivo animal model, ectopic neo-tendon regeneration was observed in subcutaneous transplanted MSC-alginate constructs, as confirmed by histological and immunohistochemical staining for protein markers specific for tendons. Interestingly, in our quantitative PCR and in vivo histomorphometric analyses, PDLSCs showed significantly greater capacity for tendon regeneration than GMSCs or hBMMSCs (P < 0.05). Altogether, these findings indicate that periodontal ligament and gingival tissues can be considered as suitable stem cell sources for tendon engineering. PDLSCs and GMSCs encapsulated in TGF-β3-loaded RGD-modified alginate microspheres are promising candidates for tendon regeneration.

  15. [Treatment of unrecent patellar tendon tear with semitendinous and gracilis tendons].

    PubMed

    Estrada-Malacón, C A; García-Estrada, G A

    2011-01-01

    The patellar tendon lesion is very important due to the role of this tendon on the conformation of the extensor mechanism of the quadriceps. When the terminal end of this mechanism is injured, the extensor function of the knee is completely lost and thus the functional capability of the involved limb is completely disrupted.

  16. MR Imaging and US of the Wrist Tendons.

    PubMed

    Plotkin, Benjamin; Sampath, Srihari C; Sampath, Srinath C; Motamedi, Kambiz

    2016-10-01

    The tendons of the wrist are commonly symptomatic. They can be injured, infected, or inflamed. Magnetic resonance imaging and ultrasonography are useful tools for evaluating the wrist. Pathologic conditions of the wrist tendons include de Quervain tenosynovitis, extensor carpi ulnaris tendinopathy, rheumatoid tenosynovitis, infectious synovitis, tendon tears, hydroxyapatite deposition disease, intersection syndrome, tenosynovial giant cell tumor, and fibroma of the tendon sheath. In this article, we review the normal appearance of the wrist tendons, discuss relevant anatomy, and give an overview of common pathologic conditions affecting the wrist tendons. Online supplemental material is available for this article. (©)RSNA, 2016.

  17. Acute partial rupture of the common extensor tendon.

    PubMed

    Kachrimanis, G; Papadopoulou, O

    2010-06-01

    Rupture of the common extensor tendon is the most common acute tendon injury of the elbow. The authors describe a case of a patient with a clinical history of tendinopathy caused by functional overload of the common extensor tendon, treated also with infiltrations of steroids, and subsequent partial rupture of the tendon during sport activity. The diagnosis was made clinically and at ultrasound (US) examination; US follow-up after some time showed the healing of the lesion. This case confirms that injections of steroids may be a contributory cause of tendon rupture, and emphasizes the sensitivity and specificity of US in the study of pathologies of the elbow tendons.

  18. Novel Model of Tendon Regeneration Reveals Distinct Cell Mechanisms Underlying Regenerative and Fibrotic Tendon Healing

    PubMed Central

    Howell, Kristen; Chien, Chun; Bell, Rebecca; Laudier, Damien; Tufa, Sara F.; Keene, Douglas R.; Andarawis-Puri, Nelly; Huang, Alice H.

    2017-01-01

    To date, the cell and molecular mechanisms regulating tendon healing are poorly understood. Here, we establish a novel model of tendon regeneration using neonatal mice and show that neonates heal via formation of a ‘neo-tendon’ that differentiates along the tendon specific lineage with functional restoration of gait and mechanical properties. In contrast, adults heal via fibrovascular scar, aberrant differentiation toward cartilage and bone, with persistently impaired function. Lineage tracing identified intrinsic recruitment of Scx-lineage cells as a key cellular mechanism of neonatal healing that is absent in adults. Instead, adult Scx-lineage tenocytes are not recruited into the defect but transdifferentiate into ectopic cartilage; in the absence of tenogenic cells, extrinsic αSMA-expressing cells persist to form a permanent scar. Collectively, these results establish an exciting model of tendon regeneration and uncover a novel cellular mechanism underlying regenerative vs non-regenerative tendon healing. PMID:28332620

  19. Extensor-tendons reconstruction using autogenous palmaris longus tendon grafting for rheumatoid arthritis patients

    PubMed Central

    Chu, Po-Jung; Lee, Hung-Maan; Hou, Yao-Tung; Hung, Sheng-Tsai; Chen, Jung-Kuei; Shih, Jui-Tien

    2008-01-01

    Background The purpose of the study is to retrospectively review the clinical outcome of our study population of middle-aged RA patients who had suffered extensor-tendon rupture. We reported the outcome of autogenous palmaris tendon grafting of multiple extensor tendons at wrist level in 14 middle-aged rheumatoid patients. Methods Between Feb. 2000 to Feb. 2004, thirty-six ruptured wrist level extensor tendons were reconstructed in fourteen rheumatoid patients (11 women and three men) using autogenous palmaris longus tendon as a free interposition graft. In each case, the evaluation was based on both subjective and objective criteria, including the range of MCP joint flexion after surgery, the extension lag at the metacarpophalangeal joint before and after surgery, and the ability of the patient to work. Results and Discussion The average of follow-up was 54.1 months (range, 40 to 72 months). The average range of MCP joint flexion after reconstruction was 66°. The extension lag at the metacarpophalangeal joint significantly improved from a preoperative mean of 38° (range, 25°–60°) to a postoperative mean of 16° (range, 0°–30°). Subjectively all patients were satisfied with the clinical results, and achieved a return to their level of ability before tendon rupture. We found good functional results in our series of interposition grafting using palmaris longus to reconstruct extensor tendon defects in the rheumatoid patients. Conclusion Reconstruction for multiple tendon ruptures is a salvage procedure that is often associated with extensor lag and impairment of overall function. Early aggressive treatment of extensor tendon reconstruction using autogenous palmaris longus tendon as a free interposition graft in the rheumatoid wrist is another viable option to achieve good clinical functional result. PMID:18435845

  20. [The Achilles tendon in sports].

    PubMed

    Segesser, B; Goesele, A; Renggli, P

    1995-06-01

    Achillodynia is a generic term for various types of ailments in the region of the Achilles tendon. For adequate therapy a specific diagnosis is absolutely necessary. Besides an accurate anamnesis and the right choice of terrain and shoes, as well as a clinical examination where one has to specifically keep an eye on muscular imbalance between the gastrocnemius and the soleus muscle and disorders of the ligamentous control of the calcaneus caused by fibular ligament instabilities, a procedure such as radiology, ultrasound, and MR imaging is inevitable. From the differential diagnosis point of view a distinction between peritendinitis, mechanically triggered bursitis (calcaneal and subachilles), bony alterations of the calcaneus (calcaneus spur, Haglund exostosis persistent nucleus of the apophysis, fatigue fracture, etc) and a partial or total rupture (a one-time occurrence or multiple occurrences) has to be made. Occasionally, entrapment of the ramus calcaneus of the sural nerve causes calcaneal pain. If clinically not confirmed, lumbar pain ought to be taken into consideration (discopathy, Bechterew disease, etc). Metabolic disorders (especially uric acid) and underlying rheumatic diseases must be excluded. The therapy of achillodynia includes local and peroral antiphlogistic medication as a concomitant measure. More important is the causal influence of etiological factors, i.e., the correction of muscular imbalance, ensuring control of the calcaneus through bandages and adjustment of sport shoes, changes in training buildup and exercise intensity, just to mention a few. If necessary, surgically splitting the peritendineum, sanitation of a partial rupture, bursectomy and removal of mechanically obstructive exostosis must be done.

  1. Dynamic loading of electrospun yarns guides mesenchymal stem cells towards a tendon lineage

    PubMed Central

    Bosworth, L.A.; Rathbone, S.R.; Bradley, R.S.; Cartmell, S.H.

    2014-01-01

    Alternative strategies are required when autograft tissue is not sufficient or available to reconstruct damaged tendons. Electrospun fibre yarns could provide such an alternative. This study investigates the seeding of human mesenchymal stem cells (hMSC) on electrospun yarns and their response when subjected to dynamic tensile loading. Cell seeded yarns sustained 3600 cycles per day for 21 days. Loaded yarns demonstrated a thickened cell layer around the scaffold׳s exterior compared to statically cultured yarns, which would suggest an increased rate of cell proliferation and/or matrix deposition, whilst maintaining a predominant uniaxial cell orientation. Tensile properties of cell-seeded yarns increased with time compared to acellular yarns. Loaded scaffolds demonstrated an up-regulation in several key tendon genes, including collagen Type I. This study demonstrates the support of hMSCs on electrospun yarns and their differentiation towards a tendon lineage when mechanically stimulated. PMID:25129861

  2. Micropatterning of nanocomposite polymer scaffolds using sacrificial phosphate glass fibers for tendon tissue engineering applications.

    PubMed

    Alshomer, Feras; Chaves, Camilo; Serra, Tiziano; Ahmed, Ifty; Kalaskar, Deepak M

    2017-01-20

    This study presents a simple and reproducible method of micropatterning the novel nanocomposite polymer (POSS-PCU) using a sacrificial phosphate glass fiber template for tendon tissue engineering applications. The diameters of the patterned scaffolds produced were dependent on the diameter of the glass fibers (15 μm) used. Scaffolds were tested for their physical properties and reproducibility using various microscopy techniques. For the first time, we show that POSS-PCU supports growth of human tenocytes cells. Furthermore, we show that cellular alignment, their biological function and expression of various tendon related proteins such as scleraxis, collagen I and III, tenascin-C are significantly elevated on the micropatterned polymer surfaces compared to flat samples. This study demonstrated a simple, reproducible method of micropatterning POSS-PCU nanocomposite polymer for novel tendon repair applications, which when provided with physical cues could help mimic the microenvironment of tenocytes cells.

  3. After rotator cuff tears, the remaining (intact) tendons are mechanically altered.

    PubMed

    Perry, Stephanie M; Getz, Charles L; Soslowsky, Louis J

    2009-01-01

    Although presumed, damage in the remaining (intact) rotator cuff tendons in the presence of an isolated supraspinatus tendon tear or multiple tendon tear has not been well studied. This study used an animal model of multiple rotator cuff tendon tears to investigate alterations in the remaining (intact) tendon mechanical properties at 4 and 8 weeks after injury. Twenty-four rats served as uninjured controls, whereas 72 were divided among 3 tendon detachment groups: supraspinatus tendon detachment, supraspinatus + infraspinatus tendon detachment, and supraspinatus + subscapularis tendon detachment. The remaining (intact) rotator cuff tendons had decreased mechanical properties in the presence of rotator cuff tears. The remaining (intact) subscapularis and infraspinatus tendon cross-sectional areas increased, whereas tendon modulus decreased after tears of both 1 and 2 tendons. The remaining (intact) tendon cross-sectional areas continued to increase with time after injury. These alterations could potentially lead to further tendon damage and tear progression.

  4. The effect of tendon surface treatment on cell attachment for potential enhancement of tendon graft healing: an ex vivo model.

    PubMed

    Hashimoto, Takahiro; Sun, Yu-Long; An, Kai-Nan; Amadio, Peter C; Zhao, Chunfeng

    2012-12-01

    For both tendon allografts and autografts, the surface, initially optimized for gliding, may not be ideal to facilitate tissue integration for graft healing to host tendon or bone. As a prelude to studying tendon-bone integration, we investigated the effect of surface treatments with trypsin or mechanical abrasion on cell attachment to the tendon surface in a canine ex vivo intrasynovial tendon tissue culture model. Intrasynovial tendon allograft surfaces were seeded with cells after the following treatments: (1) no treatment, (2) mechanical abrasion, (3) trypsin, and (4) abrasion and trypsin. The area covered by cells was determined using confocal laser microscopy at one and two weeks. Results were compared to untreated extrasynovial tendon. Additional tendons were characterized with scanning electron microscopy. Tendons with trypsin treatment had significantly more surface coverage with cells than the other groups, after both one and two weeks of culture. In terms of the cellular shape and size, cells on tendons with trypsin treatment spread more and were more polygonal in shape, whereas tendons with mechanical abrasion with/without trypsin treatment contained smaller, more spindle-like cells. Surface roughening can affect cell behavior with topographical stimulation. Trypsin surface digestion exposes a mesh-like structure on the tendon surface, which could enhance cell adherence and, possibly, tendon/bone healing.

  5. Robot Arm with Tendon Connector Plate and Linear Actuator

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Diftler, Myron A. (Inventor); Bridgwater, Lyndon (Inventor); Nguyen, Vienny (Inventor); Millerman, Alexander (Inventor)

    2014-01-01

    A robotic system includes a tendon-driven end effector, a linear actuator, a flexible tendon, and a plate assembly. The linear actuator assembly has a servo motor and a drive mechanism, the latter of which translates linearly with respect to a drive axis of the servo motor in response to output torque from the servo motor. The tendon connects to the end effector and drive mechanism. The plate assembly is disposed between the linear actuator assembly and the tendon-driven end effector and includes first and second plates. The first plate has a first side that defines a boss with a center opening. The second plate defines an accurate through-slot having tendon guide channels. The first plate defines a through passage for the tendon between the center opening and a second side of the first plate. A looped end of the flexible tendon is received within the tendon guide channels.

  6. Nutritional research may be useful in treating tendon injuries.

    PubMed

    Curtis, Luke

    2016-06-01

    Tendon injures cause a great deal of disability and pain, and increase medical costs. However, relatively little is known about tendon biology and healing. Many tendon-related surgical procedures are not very successful and leave the patient with essentially a chronic injury. New therapeutic approaches for tendon injury are needed. Preliminary evidence suggests that various nutrients such as proteins, amino acids (leucine, arginine, glutamine), vitamins C and D, manganese, copper, zinc, and phytochemicals may be useful in improving tendon growth and healing. More research on nutrition and tendon health is needed. Because many nutrients are required for tendon health, nutritional interventions involving multiple nutrients may be more effective than single-nutrient strategies. In the future, ideal treatment regimens for tendon injuries may include a multifaceted "bundle" of nutrition, drugs, biologic products, extracellular matrix therapies, exercise/physical therapy, and possibly surgery.

  7. The use of nanotechnology in tendon regeneration and repair.

    PubMed

    Oragui, Emeka; Sachinis, Nick; Hope, Natalie; Khan, Wasim S; Adesida, Adetola

    2012-01-01

    Tendon injuries are common and due to their limited capacity for self-healing, the biomechanical and functional properties of healed tendon are usually inferior to normal tissue. Tissue engineering offers the hope of regenerating tendon tissue with the same biomechanical properties of the native undamaged tissue by augmenting the regenerative process of in vivo tissue or producing a functional tissue in vitro that can be implanted into the defective tendon site. Current research on tendon tissue engineering has focused on the role of stem cell and tendon derived cell therapy, scaffolds, chemical and physical stimulation and gene-therapeutic approaches. In this review we review the important functional anatomy and pathomechanics of tendon injury and discuss the current advances in tendon tissue engineering.

  8. Modelling approaches for evaluating multiscale tendon mechanics

    PubMed Central

    Fang, Fei; Lake, Spencer P.

    2016-01-01

    Tendon exhibits anisotropic, inhomogeneous and viscoelastic mechanical properties that are determined by its complicated hierarchical structure and varying amounts/organization of different tissue constituents. Although extensive research has been conducted to use modelling approaches to interpret tendon structure–function relationships in combination with experimental data, many issues remain unclear (i.e. the role of minor components such as decorin, aggrecan and elastin), and the integration of mechanical analysis across different length scales has not been well applied to explore stress or strain transfer from macro- to microscale. This review outlines mathematical and computational models that have been used to understand tendon mechanics at different scales of the hierarchical organization. Model representations at the molecular, fibril and tissue levels are discussed, including formulations that follow phenomenological and microstructural approaches (which include evaluations of crimp, helical structure and the interaction between collagen fibrils and proteoglycans). Multiscale modelling approaches incorporating tendon features are suggested to be an advantageous methodology to understand further the physiological mechanical response of tendon and corresponding adaptation of properties owing to unique in vivo loading environments. PMID:26855747

  9. No Telescoping Effect with Dual Tendon Vibration

    PubMed Central

    Bellan, Valeria; Wallwork, Sarah B.; Stanton, Tasha R.; Reverberi, Carlo; Gallace, Alberto; Moseley, G. Lorimer

    2016-01-01

    The tendon vibration illusion has been extensively used to manipulate the perceived position of one’s own body part. However, findings from previous research do not seem conclusive sregarding the perceptual effect of the concurrent stimulation of both agonist and antagonist tendons over one joint. On the basis of recent data, it has been suggested that this paired stimulation generates an inconsistent signal about the limb position, which leads to a perceived shrinkage of the limb. However, this interesting effect has never been replicated. The aim of the present study was to clarify the effect of a simultaneous and equal vibration of the biceps and triceps tendons on the perceived location of the hand. Experiment 1 replicated and extended the previous findings. We compared a dual tendon stimulation condition with single tendon stimulation conditions and with a control condition (no vibration) on both ‘upward-downward’ and ‘towards-away from the elbow’ planes. Our results show a mislocalisation towards the elbow of the position of the vibrated arm during dual vibration, in line with previous results; however, this did not clarify whether the effect was due to arm representation contraction (i.e., a ‘telescoping’ effect). Therefore, in Experiment 2 we investigated explicitly and implicitly the perceived arm length during the same conditions. Our results clearly suggest that in all the vibration conditions there was a mislocalisation of the entire arm (including the elbow), but no evidence of a contraction of the perceived arm length. PMID:27305112

  10. Ethinyl oestradiol administration in women suppresses synthesis of collagen in tendon in response to exercise

    PubMed Central

    Hansen, Mette; Koskinen, Satu O; Petersen, Susanne G; Doessing, Simon; Frystyk, Jan; Flyvbjerg, Allan; Westh, Eva; Magnusson, S Peter; Kjaer, Michael; Langberg, Henning

    2008-01-01

    Women are at greater risk than men of sustaining certain kinds of injury and diseases of collagen-rich tissues. To determine whether a high level of oestradiol has an acute influence on collagen synthesis in tendons at rest and in response to exercise, one-legged kicking exercise was performed for 60 min at 67% of maximum power by healthy, young oral contraceptive (OC) users when circulating synthetic (ethinyl) oestradiol was high (n = 11, HE-OC) and compared to similar women who had never used OCs when circulating endogenous oestrogen was low (n = 12, LE-NOC). Interstitial fluid was collected 24 h post-exercise through microdialysis catheters placed anterior to the patellar tendon in both legs and subsequently analysed for the amino-terminal propeptide of type I collagen (PINP), a marker of tendon collagen synthesis. To determine the long-term effect of OC usage, patellar tendon cross-sectional area (CSA) was measured by magnetic resonance imaging (MRI). A lower exercise-induced increase in tendon collagen synthesis was observed in HE-OC than in LE-NOC (ΔPINP (mean ±s.e.m.) 1.5 ± 5.3 versus 24.2 ± 9.4 ng ml−1, P < 0.05). Furthermore, serum and the interstitial peritendinous tissue concentrations of insulin-like growth factor I (IGF-I) and IGF-binding proteins showed a reduced bioavailability in HE-OC compared with results in LE-NOC. No difference in patellar tendon CSA was observed between groups. In conclusion, the selective increase in tendon collagen synthesis in LE-NOC but not HE-OC 24 h post-exercise is consistent with the hypothesis that oestradiol inhibits exercise-induced collagen synthesis in human tendon. The mechanism behind this is either a direct effect of oestradiol, or an indirect effect via a reduction in levels of free IGF-I. However, the data did not indicate any long-term effect on tendon size associated with chronic OC use. PMID:18420709

  11. Structure-function relationships in tendons: a review

    PubMed Central

    Benjamin, M; Kaiser, E; Milz, S

    2008-01-01

    The purpose of the current review is to highlight the structure-function relationship of tendons and related structures to provide an overview for readers whose interest in tendons needs to be underpinned by anatomy. Because of the availability of several recent reviews on tendon development and entheses, the focus of the current work is primarily directed towards what can best be described as the ‘tendon proper’ or the ‘mid-substance’ of tendons. The review covers all levels of tendon structure from the molecular to the gross and deals both with the extracellular matrix and with tendon cells. The latter are often called ‘tenocytes’ and are increasingly recognized as a defined cell population that is functionally and phenotypically distinct from other fibroblast-like cells. This is illustrated by their response to different types of mechanical stress. However, it is not only tendon cells, but tendons as a whole that exhibit distinct structure-function relationships geared to the changing mechanical stresses to which they are subject. This aspect of tendon biology is considered in some detail. Attention is briefly directed to the blood and nerve supply of tendons, for this is an important issue that relates to the intrinsic healing capacity of tendons. Structures closely related to tendons (joint capsules, tendon sheaths, pulleys, retinacula, fat pads and bursae) are also covered and the concept of a ‘supertendon’ is introduced to describe a collection of tendons in which the function of the whole complex exceeds that of its individual members. Finally, attention is drawn to the important relationship between tendons and fascia, highlighted by Wood Jones in his concept of an ‘ectoskeleton’ over half a century ago – work that is often forgotten today. PMID:18304204

  12. p38 MAPK Signaling in Postnatal Tendon Growth and Remodeling

    PubMed Central

    Schwartz, Andrew J.; Sarver, Dylan C.; Sugg, Kristoffer B.; Dzierzawski, Justin T.; Gumucio, Jonathan P.; Mendias, Christopher L.

    2015-01-01

    Tendon is a dynamic tissue whose structure and function is influenced by mechanical loading, but little is known about the fundamental mechanisms that regulate tendon growth and remodeling in vivo. Data from cultured tendon fibroblasts indicated that the p38 MAPK pathway plays an important role in tendon fibroblast proliferation and collagen synthesis in vitro. To gain greater insight into the mechanisms of tendon growth, and explore the role of p38 MAPK signaling in this process, we tested the hypotheses that inducing plantaris tendon growth through the ablation of the synergist Achilles tendon would result in rapid expansion of a neotendon matrix surrounding the original tendon, and that treatment with the p38 MAPK inhibitor SB203580 would prevent this growth. Rats were treated with vehicle or SB203580, and subjected to synergist ablation by bilateral tenectomy of the Achilles tendon. Changes in histological and biochemical properties of plantaris tendons were analyzed 3, 7, or 28 days after overload, and comparisons were made to non-overloaded animals. By 28 days after overload, tendon mass had increased by 30% compared to non-overloaded samples, and cross-sectional area (CSA) increased by around 50%, with most of the change occurring in the neotendon. The expansion in CSA initially occurred through the synthesis of a hyaluronic acid rich matrix that was progressively replaced with mature collagen. Pericytes were present in areas of active tendon growth, but never in the original tendon ECM. Inhibition of p38 MAPK resulted in a profound decrease in IL6 expression, and had a modest effect on the expression of other ECM and cell proliferation genes, but had a negligible impact on overall tendon growth. The combined results from this study provided novel insights into tendon mechanobiology, and suggest that p38 MAPK signaling does not appear to be necessary for tendon growth in vivo. PMID:25768932

  13. The influence of ageing and exercise on tendon growth and degeneration--hypotheses for the initiation and prevention of strain-induced tendinopathies.

    PubMed

    Smith, R K W; Birch, H L; Goodman, S; Heinegård, D; Goodship, A E

    2002-12-01

    Strain-induced tendinopathy is a common injury in both human and equine athletes, with increasing incidence associated with greater involvement in sport and an increasingly aged population. This paper reviews our studies on the abundant non-collagenous protein, cartilage oligomeric matrix protein (COMP), in equine tendons. Its variation between tendon type and site, age and exercise has provided an insight into how age and exercise influence tendon growth and maturation. Tendons can be broadly divided into two types, reflecting their different matrix composition and function: the energy-storing tendons used for weight-bearing and locomotion, which suffer a high incidence of strain-induced tendinopathy, and positional tendons involved in limb placement or manipulative skills. It would appear that while energy-storing tendon can respond to the mechanical forces applied to it during growth, there is no evidence that it can do so after skeletal maturity. Instead, cumulative fatigue damage causes degeneration at the molecular level, potentially weakening it and increasing the risk of clinical injury. Appropriate exercise regimes early in life may help to improve the quality of growing tendon, thereby reducing the incidence of injury during ageing or subsequent athletic career.

  14. Shear Elastic Modulus on Patellar Tendon Captured from Supersonic Shear Imaging: Correlation with Tangent Traction Modulus Computed from Material Testing System and Test-Retest Reliability.

    PubMed

    Zhang, Zhi Jie; Fu, Siu Ngor

    2013-01-01

    Characterization of the elastic properties of a tendon could enhance the diagnosis and treatment of tendon injuries. The purpose of this study was to examine the correlation between the shear elastic modulus on the patellar tendon captured from a Supersonic Shear Imaging (SSI) and the tangent traction modulus computed from a Material testing system (MTS) on 8 fresh patellar pig tendons (Experiment I). Test-retest reliability of the shear elastic modulus captured from the SSI was established in Experiment II on 22 patellar tendons of 11 healthy human subjects using the SSI. Spearman Correlation coefficients for the shear elastic modulus and tangent traction modulus ranged from 0.82 to 1.00 (all p<0.05) on the 8 tendons. The intra and inter-operator reliabilities were 0.98 (95% CI: 0.93-0.99) and 0.97 (95% CI: 0.93-0.98) respectively. The results from this study demonstrate that the shear elastic modulus of the patellar tendon measured by the SSI is related to the tangent traction modulus quantified by the MTS. The SSI shows good intra and inter-operator repeatability. Therefore, the present study shows that SSI can be used to assess elastic properties of a tendon.

  15. Tendon neuroplastic training: changing the way we think about tendon rehabilitation: a narrative review

    PubMed Central

    Rio, Ebonie; Kidgell, Dawson; Moseley, G Lorimer; Docking, Sean; Purdam, Craig; Cook, Jill

    2016-01-01

    Tendinopathy can be resistant to treatment and often recurs, implying that current treatment approaches are suboptimal. Rehabilitation programmes that have been successful in terms of pain reduction and return to sport outcomes usually include strength training. Muscle activation can induce analgesia, improving self-efficacy associated with reducing one's own pain. Furthermore, strength training is beneficial for tendon matrix structure, muscle properties and limb biomechanics. However, current tendon rehabilitation may not adequately address the corticospinal control of the muscle, which may result in altered control of muscle recruitment and the consequent tendon load, and this may contribute to recalcitrance or symptom recurrence. Outcomes of interest include the effect of strength training on tendon pain, corticospinal excitability and short interval cortical inhibition. The aims of this concept paper are to: (1) review what is known about changes to the primary motor cortex and motor control in tendinopathy, (2) identify the parameters shown to induce neuroplasticity in strength training and (3) align these principles with tendon rehabilitation loading protocols to introduce a combination approach termed as tendon neuroplastic training. Strength training is a powerful modulator of the central nervous system. In particular, corticospinal inputs are essential for motor unit recruitment and activation; however, specific strength training parameters are important for neuroplasticity. Strength training that is externally paced and akin to a skilled movement task has been shown to not only reduce tendon pain, but modulate excitatory and inhibitory control of the muscle and therefore, potentially tendon load. An improved understanding of the methods that maximise the opportunity for neuroplasticity may be an important progression in how we prescribe exercise-based rehabilitation in tendinopathy for pain modulation and potentially restoration of the corticospinal

  16. 21 CFR 888.3025 - Passive tendon prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) Identification. A passive tendon prosthesis is a device intended to be implanted made of silicon elastomer or a... flexor tendon of the hand. The device is implanted for a period of 2 to 6 months to aid growth of a new tendon sheath. The device is not intended as a permanent implant nor to function as a replacement for...

  17. Tibialis posterior tendon rupture: a cause of rheumatoid flat foot.

    PubMed

    Downey, D J; Simkin, P A; Mack, L A; Richardson, M L; Kilcoyne, R F; Hansen, S T

    1988-03-01

    Flat foot, a major cause of foot pain and disability, may result from rupture of the tibialis posterior tendon. We describe 2 patients with rheumatoid arthritis who developed flat feet secondary to surgically confirmed tendon rupture, and we discuss the anatomy and diagnosis of this condition. In the second patient, we also present the results of tendon imaging with both magnetic resonance and ultrasound.

  18. An Overview of the Management of Flexor Tendon Injuries

    PubMed Central

    Griffin, M; Hindocha, S; Jordan, D; Saleh, M; Khan, W

    2012-01-01

    Flexor tendon injuries still remain a challenging condition to manage to ensure optimal outcome for the patient. Since the first flexor tendon repair was described by Kirchmayr in 1917, several approaches to flexor tendon injury have enabled successful repairs rates of 70-90%. Primary surgical repair results in better functional outcome compared to secondary repair or tendon graft surgery. Flexor tendon injury repair has been extensively researched and the literature demonstrates successful repair requires minimal gapping at the repair site or interference with tendon vascularity, secure suture knots, smooth junction of tendon end and having sufficient strength for healing. However, the exact surgical approach to achieve success being currently used among surgeons is still controversial. Therefore, this review aims to discuss the results of studies demonstrating the current knowledge regarding the optimal approach for flexor tendon repair. Post-operative rehabilitation for flexor tendon surgery is another area, which has caused extensive debate in hand surgery. The trend to more active mobilisation protocols seems to be favoured but further study in this area is needed to find the protocol, which achieves function and gliding but avoids rupture of the tendons. Lastly despite success following surgery complications commonly still occur post surgery, including adhesion formation, tendon rupture and stiffness of the joints. Therefore, this review aims to discuss the appropriate management of these difficulties post surgery. New techniques in management of flexor tendon will also be discussed including external laser devices, addition of growth factors and cytokines. PMID:22431948

  19. Acute flexor tendon repairs in zone II.

    PubMed

    Coats, Robert W; Echevarría-Oré, Julio C; Mass, Daniel P

    2005-05-01

    Flexor tendon repair in zone II is still a technically demanding procedure, but the outcomes have become more predictable and satisfying. Of keystone importance for obtaining the goals of normal strength and gliding of repaired flexor tendons are an atraumatic surgical technique, an appropriate suture material, a competent pulley system, and the use of early motion rehabilitation protocols. The overall goal of hand and finger function also implies timely addressing of neurovascular injuries. New devices such as the TenoFix (Ortheon Medical; Winter Park, Florida) have shown adequate strength in the laboratory but are bulky and untested for work of flexion. Insufficient clinical data and high cost may prevent widespread use.

  20. Flexor Tendon Pulley Injuries in Rock Climbers.

    PubMed

    King, Elizabeth A; Lien, John R

    2017-02-01

    Closed pulley ruptures are rare in the general population but occur more frequently in rock climbers due to biomechanical demands on the hand. Injuries present with pain and swelling over the affected pulley, and patients may feel or hear a pop at the time of injury. Sequential pulley ruptures are required for clinical bowstringing of the flexor tendons. Ultrasound confirms diagnosis of pulley rupture and evaluates degree of displacement of the flexor tendons. Isolated pulley ruptures frequently are treated conservatively with early functional rehabilitation. Sequential pulley ruptures require surgical reconstruction. Most climbers are able to return to their previous activity level.

  1. Tendon ruptures: mallet, flexor digitorum profundus.

    PubMed

    Yeh, Peter C; Shin, Steven S

    2012-08-01

    Mallet injuries are the most common closed tendon injury in the athlete. Flexor digitorum profundus ruptures are rare in baseball, but are common injuries in contact sports. The diagnosis for each condition is based on clinical examination, although radiographs should be evaluated for a possible bony component. Treatment for mallet injury depends on the athlete's goals of competition and understanding of the consequences of any treatment chosen. Gripping, throwing, and catching would be restricted or impossible with the injured finger immobilized. Treatment of FDP ruptures is almost always surgical and requires reattachment of the torn tendon to the distal phalanx.

  2. Variability in Hoffmann and tendon reflexes in healthy male subjects

    NASA Technical Reports Server (NTRS)

    Good, E.; Do, S.; Jaweed, M.

    1992-01-01

    There is a time dependent decrease in amplitude of H- and T-reflexes during Zero-G exposure and subsequently an increase in the amplitude of the H-reflex 2-4 hours after return to a 1-G environment. These alterations have been attributed to the adaptation of the human neurosensory system to gravity. The Hoffman reflex (H-reflex) is an acknowledged method to determine the integrity of the monosynaptic reflex arc. However deep tendon reflexes (DTR's or T-reflexes), elicited by striking the tendon also utilize the entire reflex arc. The objective of this study was to compare the variability in latency and amplitude of the two reflexes in healthy subjects. Methods: Nine healthy male subjects, 27-43 years in age, 161-175 cm in height plus 60-86 Kg in weight, underwent weekly testing for four weeks with a Dan-Tec EMG counterpoint EMG system. Subjects were studied prone and surface EMG electrodes were placed on the right and left soleus muscles. The H-reflex was obtained by stimulating the tibial nerve in the politeal fossa with a 0.2 msec square wave pulse delivered at 2 Hz until the maximum H-reflex was obtained. The T-reflex was invoked by tapping the achilles tendon with a self triggering reflex hammer connected to the EMG system. The latencies and amplitudes for the H- and T-reflexes were measured. Results: These data indicate that the amplitudes of these reflexes varied considerably. However, latencies to invoked responses were consistent. The latency of the T-reflex was approximately 3-5 msec longer than the H-reflex. Conclusion: The T-reflex is easily obtained, requires less time, and is more comfortable to perform. Qualitative data can be obtained by deploying self triggering, force plated reflex hammers both in the 1-G and Zero-G environment.

  3. Acute effect of heel-drop exercise with varying ranges of motion on the gastrocnemius aponeurosis-tendon's mechanical properties.

    PubMed

    Jeong, Siwoo; Lee, Dae-Yeon; Choi, Dong-Sung; Lee, Hae-Dong

    2014-06-01

    The objectives of this study was to investigate the acute effects of various magnitudes of tendon strain on the mechanical properties of the human medial gastrocnemius (MG) in vivo during controlled heel-drop exercises. Seven male and seven female volunteers performed two different exercises executed one month apart: one was a heel-drop exercise on a block (HDB), and the other was a heel-drop exercise on level floor (HDL). In each regimen, the subjects completed a session of 150 heel-drop exercises (15 repetitions×10 sets; with a 30 s rest following each set). Before and immediately after the heel-drop exercise, the ankle plantar flexor torque and elongation of the MG were measured using a combined measurement system of dynamometry and ultrasonography and then the MG tendon strain and stiffness were evaluated in each subject. The tendon stiffness measured prior to the exercises was not significantly different between the two groups 23.7±10.6N/mm and 24.1±10.0N/mm for the HDB and HDL, respectively (p>.05). During the heel-drop exercise, it was found that the tendon strain during the heel-drop exercise on a block (8.4±3.7%) was significantly higher than the strain measured on the level floor (5.4±3.8%) (p<.05). In addition, the tendon stiffness following the heel-drop exercise on a block (32.3±12.2N/mm) was significantly greater than the tendon stiffness measured following the heel-drop exercise on the level floor (25.4±11.4N/mm) (p<.05). The results of this study suggest that tendon stiffness immediately following a heel-drop exercise depends on the magnitude of tendon strain.

  4. Full-thickness tears of the supraspinatus tendon: A three-dimensional finite element analysis.

    PubMed

    Quental, C; Folgado, J; Monteiro, J; Sarmento, M

    2016-12-08

    Knowledge regarding the likelihood of propagation of supraspinatus tears is important to allow an early identification of patients for whom a conservative treatment is more likely to fail, and consequently, to improve their clinical outcome. The aim of this study was to investigate the potential for propagation of posterior, central, and anterior full-thickness tears of different sizes using the finite element method. A three-dimensional finite element model of the supraspinatus tendon was generated from the Visible Human Project data. The mechanical behaviour of the tendon was fitted from experimental data using a transversely isotropic hyperelastic constitutive model. The full-thickness tears were simulated at the supraspinatus tendon insertion by decreasing the interface area. Tear sizes from 10% to 90%, in 10% increments, of the anteroposterior length of the supraspinatus footprint were considered in the posterior, central, and anterior regions of the tendon. For each tear, three finite element analyses were performed for a supraspinatus force of 100N, 200N, and 400N. Considering a correlation between tendon strain and the risk of tear propagation, the simulated tears were compared qualitatively and quantitatively by evaluating the volume of tendon for which a maximum strain criterion was not satisfied. The finite element analyses showed a significant impact of tear size and location not only on the magnitude, but also on the patterns of the maximum principal strains. The mechanical outcome of the anterior full-thickness tears was consistently, and significantly, more severe than that of the central or posterior full-thickness tears, which suggests that the anterior tears are at greater risk of propagating than the central or posterior tears.

  5. Adult Cells Combined With Platelet-Rich Plasma for Tendon Healing

    PubMed Central

    Rubio-Azpeitia, Eva; Sánchez, Pello; Delgado, Diego; Andia, Isabel

    2017-01-01

    Background: The combination of cells with platelet-rich plasma (PRP) may fulfill tendon deficits and help overcome the limited ability of tendons to heal. Purpose: To examine the suitability of 3 human cell types in combination with PRP and the potential impact of the tenocyte-conditioned media (CM) to enhance tendon healing. Study Design: Controlled laboratory study. Methods: Tenocytes, bone marrow–derived mesenchymal stem cells, and skin fibroblasts were cultured in 3-dimensional PRP hydrogels supplemented or not with CM, and cell proliferation and migration were examined. The effect of tendon-derived CM on matrix-forming phenotype and secretion of inflammatory proteins was determined through their administration to mesenchymal stem cells, tendon, and skin fibroblasts by reverse transcription quantitative polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Results: Differences were found in the matrix-forming phenotype between each of the cell types. The ratio of collagen I:collagen III was greater in bone marrow–derived mesenchymal stem cells than in skin fibroblasts and tenocytes. The bone marrow–derived mesenchymal stem cells expressed increased levels of cartilage-related genes than tenocytes or skin fibroblasts. The presence of the tenocyte-CM stimulated basic healing mechanisms including proliferation and chemotaxis in all cell types. In addition, the tenocyte-CM modified the matrix-forming phenotype of every cell type when cultured in PRP hydrogels. Each cell type secreted interleukin-6, interleukin-8, and monocyte chemotactic protein-1 in PRP hydrogels, but mesenchymal stem cells secreted less interleukin-8 and monocyte chemotactic protein-1 than tenocytes or skin fibroblasts. Conclusion: The tenocyte-CM combined with PRP stimulated tenogenesis in mesenchymal stem cells and in skin fibroblasts and reduced the secretion of inflammatory proteins. Clinical Relevance: Modifying the target tissue with PRP prior to cell

  6. Photodiode Camera Measurement of Surface Strains on Tendons during Multiple Cyclic Tests

    NASA Astrophysics Data System (ADS)

    Chun, Keyoung Jin; Hubbard, Robert Philip

    The objectives of this study are to introduce the use of a photodiode camera for measuring surface strain on soft tissue and to present some representative responses of the tendon. Tendon specimens were obtained from the hindlimbs of canines and frozen to -70°C. After thawing, specimens were mounted in the immersion bath at a room temperature (22°C), preloaded to 0.13N and then subjected to 3% of the initial length at a strain rate of 2%/sec. In tendons which were tested in two blocks of seven repeated extensions to 3% strain with a 120 seconds wait period between, the surface strains were measured with a photodiode camera and near the gripped ends generally were greater than the surface strains in the middle segment of the tendon specimens. The recovery for peak load after the rest period was consistent but the changes in patterns of surface strains after the rest period were not consistent. The advantages of a photodiode measurement of surface strains include the followings: 1) it is a noncontacting method which eliminates errors and distortions caused by clip gauges or mechanical/electronic transducers; 2) it is more accurate than previous noncontact methods, e.g. the VDA and the high speed photographic method; 3) it is a fully automatic, thus reducing labor for replaying video tapes or films and potential errors from human judgement which can occur during digitizing data from photographs. Because the photodiode camera, employs a solid state photodiode array to sense black and white images, scan targets (black image) on the surface of the tendon specimen and back lighting system (white image), and stored automatically image data for surface strains of the tendon specimen on the computer during cyclic extensions.

  7. [Traumatic and degenerative tendon lesions of the hand].

    PubMed

    Schöffl, V; Winkelmann, H-P

    2010-12-01

    Tendon lesions are the second most common injury in the hand and therefore an important factor in orthopedic patients. Most injuries are open injuries to the flexor or extensor tendons; nevertheless, also less frequent injuries such as damage to the functional system of tendon sheath and pulley or dull avulsions need to be considered. Besides the clinical examination, ultrasound and MRI have proven to be important diagnostic tools. In the postoperative course of flexor tendon injuries, the principle of early passive movement is important to trigger "intrinsic" tendon healing to guarantee a good outcome.

  8. The role of animal models in tendon research

    PubMed Central

    Hast, M. W.; Zuskov, A.; Soslowsky, L. J.

    2014-01-01

    Tendinopathy is a debilitating musculoskeletal condition which can cause significant pain and lead to complete rupture of the tendon, which often requires surgical repair. Due in part to the large spectrum of tendon pathologies, these disorders continue to be a clinical challenge. Animal models are often used in this field of research as they offer an attractive framework to examine the cascade of processes that occur throughout both tendon pathology and repair. This review discusses the structural, mechanical, and biological changes that occur throughout tendon pathology in animal models, as well as strategies for the improvement of tendon healing. Cite this article: Bone Joint Res 2014;3:193–202. PMID:24958818

  9. Mechanical properties of UV irradiated rat tail tendon (RTT) collagen.

    PubMed

    Sionkowska, Alina; Wess, Tim

    2004-04-01

    The mechanical properties of RTT collagen tendon before and after UV irradiation have been investigated by mechanical testing (Instron). Air-dried tendon were submitted to treatment with UV irradiation (wavelength 254 nm) for different time intervals. The changes in such mechanical properties as breaking strength and percentage elongation have been investigated. The results have shown, that the mechanical properties of the tendon were greatly affected by time of UV irradiation. Ultimate tensile strength and ultimate percentage elongation decreased after UV irradiation of the tendon. Increasing UV irradiation leads to a decrease in Young's modulus of the tendon.

  10. Mechanical Characterization and Shape Optimization of Fascicle-Like 3D Skeletal Muscle Tissues Contracted with Electrical and Optical Stimuli

    PubMed Central

    Neal, Devin; Sakar, Mahmut Selman; Bashir, Rashid; Chan, Vincent

    2015-01-01

    In this study, we present a quantitative approach to construct effective 3D muscle tissues through shape optimization and load impedance matching with electrical and optical stimulation. We have constructed long, thin, fascicle-like skeletal muscle tissue and optimized its form factor through mechanical characterization. A new apparatus was designed and built, which allowed us to measure force–displacement characteristics with diverse load stiffnesses. We have found that (1) there is an optimal form factor that maximizes the muscle stress, (2) the energy transmitted to the load can be maximized with matched load stiffness, and (3) optical stimulation using channelrhodopsin2 in the muscle tissue can generate a twitch force as large as its electrical counterpart for well-developed muscle tissue. Using our tissue construct method, we found that an optimal initial diameter of 500 μm outperformed tissues using 250 μm by more than 60% and tissues using 760 μm by 105%. Using optimal load stiffness, our tissues have generated 12 pJ of energy per twitch at a peak generated stress of 1.28 kPa. Additionally, the difference in optically stimulated twitch performance versus electrically stimulated is a function of how well the overall tissue performs, with average or better performing strips having less than 10% difference. The unique mechanical characterization method used is generalizable to diverse load conditions and will be used to match load impedance to muscle tissue impedance for a wide variety of applications. PMID:25714129

  11. Severe extensor tendon attrition and multiple tendon ruptures resulting from Kienböck's disease.

    PubMed

    Ramkumar, S; Josty, I C; Sykes, P J

    2000-12-01

    Kienböck's disease is a rare but recognized cause of chronic wrist pain. Occasionally, complications arise leading to tendon rupture. The authors present the first reported case of attrition to all extensors of the hand, and extensor tendon rupture to the little finger in a patient with a 45-year history of Kienböck's disease. This is also the first reported incidence of this complication in whites. Clinical features, surgical management, and the successful outcome are discussed.

  12. Achilles Tendon Rupture: Avoiding Tendon Lengthening during Surgical Repair and Rehabilitation

    PubMed Central

    Maquirriain, Javier

    2011-01-01

    Achilles tendon rupture is a serious injury for which the best treatment is still controversial. Its primary goal should be to restore normal length and tension, thus obtaining an optimal function. Tendon elongation correlates significantly with clinical outcome; lengthening is an important cause of morbidity and may produce permanent functional impairment. In this article, we review all factors that may influence the repair, including the type of surgical technique, suture material, and rehabilitation program, among many others. PMID:21966048

  13. Abductor pollicis longus tendon division with swan neck thumb deformity.

    PubMed

    Zacharia, Balaji; Puthezhath, Kishore

    2012-08-01

    Swan neck thumb deformity can be caused by osteoarthritis, rheumatoid arthritis, systemic lupus erythematosus, tendon transfers and paralytic diseases. Abductor pollicis longus is one of the major stabilizing tendon of the carpometacarpal joint of thumb. To the best of our knowledge, swan neck thumb deformity owing to division of abductor pollicis longus tendon is rare. In this article, we describe a case of isolated division of abductor pollicis longus tendon presenting with swan-neck deformity of thumb and discuss the mechanism, management and outcome. The patient was treated by repair of the divided tendon using palmaris longus tendon graft. At approximately 107 weeks following treatment, the patient was having full range of thumb movement and the deformity completely disappeared. We also describe the unusual mechanism whereby an isolated division of abductor pollicis longus tendon results in swan neck thumb deformity. Level of clinical evidence IV.

  14. [Flexor tendon pulley system: anatomy, pathology, treatment].

    PubMed

    Moutet, F

    2003-02-01

    Flexor tendon pulley has been very early noticed and described. Terminology usually accepted recognizes 6 arcifom pulleys (A0 to A5) and 3 cruciform pulleys (C1 to C3). Anatomy and physiology of this flexor tendon gliding and reflection system at the level of the digital sheet are exposed. The integrity necessity of this system became obvious regarding the flexor tendons repair. Four main pathologies may be concerned: the trigger finger congenital or progressive, due to a chondroid metaplasia of the A1 pulley; tenosynovial ganglions arising at the weak point between A1 and A2 pulley; lesions of the flexor tendon sheet during traumatic lacerations or surgical repairs; quite experimental lesions creating isolated ruptures of one or several pulleys which occur during sport practice, especially high level rock climbing. The repair techniques are exposed to allow to graduate and hierarchy the reparation technique regarding the pathology. A2 and A4 repair is always indicated. The best reconstruction material is an extensor retinaculum graft. But its poor surface available often draws to use conventional palmaris longus free graft.

  15. The acoustoelastic effect in prestressing tendons

    NASA Astrophysics Data System (ADS)

    Washer, Glenn Alden

    There are currently more than 130,000 prestressed concrete bridges in the United States and approximately 37,000 of these bridges are more than 30 years old. Steel tendons that are pre-tensioned to counteract the effect of design loads are critical to structural performance of these bridges. However, there are currently no accepted nondestructive evaluation techniques to evaluate the condition of these tendons. The goal of this research was to examine ultrasonic stress measurement techniques for the condition assessment of prestressing tendons. Acoustoelastic measurements were made in prestressing rods and strands, and constants are reported that relate the change in ultrasonic velocity to the change in stress. The effects of dispersion in prestressing tendons, which act as circular wave guides for ultrasonic waves, are evaluated. Factors that could effect the design of a practical sensor are examined, including temperature dependence, effect of varying boundary conditions, and the variation in acoustoelastic properties between typical materials produced by different manufacturers. It is concluded that several of these factors have a larger effect on the ultrasonic velocities than stress. Therefore, it may be impractical to design a sensor system to measure absolute stress, but measurement of stress changes from a known initial condition may be possible under certain circumstances.

  16. Mouse models in tendon and ligament research.

    PubMed

    Mienaltowski, Michael J; Birk, David E

    2014-01-01

    Mutant mouse models are valuable resources for the study of tendon and ligament biology. Many mutant mouse models are used because their manifested phenotypes mimic clinical pathobiology for several heritable disorders, such as Ehlers-Danlos Syndrome and Osteogenesis Imperfecta. Moreover, these models are helpful for discerning roles of specific genes in the development, maturation, and repair of musculoskeletal tissues. There are several categories of genes with essential roles in the synthesis and maintenance of tendon and ligament structures. The form and function of these tissues depend highly upon fibril-forming collagens, the primary extracellular macromolecules of tendons and ligaments. Models for these fibril-forming collagens, as well as for regulatory molecules like FACITs and SLRPs, are important for studying fibril assembly, growth, and maturation. Additionally, mouse models for growth factors and transcription factors are useful for defining regulation of cell proliferation, cell differentiation, and cues that stimulate matrix synthesis. Models for membrane-bound proteins assess the roles of cell-cell communication and cell-matrix interaction. In some cases, special considerations need to be given to spatio-temporal control of a gene in a model. Thus, conditional and inducible mouse models allow for specific regulation of genes of interest. Advances in mouse models have provided valuable tools for gaining insight into the form and function of tendons and ligaments.

  17. The role of tendon microcirculation in Achilles and patellar tendinopathy.

    PubMed

    Knobloch, Karsten

    2008-04-30

    Tendinopathy is of distinct interest as it describes a painful tendon disease with local tenderness, swelling and pain associated with sonographic features such as hypoechogenic texture and diameter enlargement. Recent research elucidated microcirculatory changes in tendinopathy using laser Doppler flowmetry and spectrophotometry such as at the Achilles tendon, the patellar tendon as well as at the elbow and the wrist level. Tendon capillary blood flow is increased at the point of pain. Tendon oxygen saturation as well as tendon postcapillary venous filling pressures, determined non-invasively using combined Laser Doppler flowmetry and spectrophotometry, can quantify, in real-time, how tendon microcirculation changes over with pathology or in response to a given therapy. Tendon oxygen saturation can be increased by repetitive, intermittent short-term ice applications in Achilles tendons; this corresponds to 'ischemic preconditioning', a method used to train tissue to sustain ischemic damage. On the other hand, decreasing tendon oxygenation may reflect local acidosis and deteriorating tendon metabolism. Painful eccentric training, a common therapy for Achilles, patellar, supraspinatus and wrist tendinopathy decreases abnormal capillary tendon flow without compromising local tendon oxygenation. Combining an Achilles pneumatic wrap with eccentric training changes tendon microcirculation in a different way than does eccentric training alone; both approaches reduce pain in Achilles tendinopathy. The microcirculatory effects of measures such as extracorporeal shock wave therapy as well as topical nitroglycerine application are to be studied in tendinopathy as well as the critical question of dosage and maintenance. Interestingly it seems that injection therapy using color Doppler for targeting the area of neovascularisation yields to good clinical results with polidocanol sclerosing therapy, but also with a combination of epinephrine and lidocaine.

  18. Control of position and movement is simplified by combined muscle spindle and Golgi tendon organ feedback.

    PubMed

    Kistemaker, Dinant A; Van Soest, Arthur J Knoek; Wong, Jeremy D; Kurtzer, Isaac; Gribble, Paul L

    2013-02-01

    Whereas muscle spindles play a prominent role in current theories of human motor control, Golgi tendon organs (GTO) and their associated tendons are often neglected. This is surprising since there is ample evidence that both tendons and GTOs contribute importantly to neuromusculoskeletal dynamics. Using detailed musculoskeletal models, we provide evidence that simple feedback using muscle spindles alone results in very poor control of joint position and movement since muscle spindles cannot sense changes in tendon length that occur with changes in muscle force. We propose that a combination of spindle and GTO afferents can provide an estimate of muscle-tendon complex length, which can be effectively used for low-level feedback during both postural and movement tasks. The feasibility of the proposed scheme was tested using detailed musculoskeletal models of the human arm. Responses to transient and static perturbations were simulated using a 1-degree-of-freedom (DOF) model of the arm and showed that the combined feedback enabled the system to respond faster, reach steady state faster, and achieve smaller static position errors. Finally, we incorporated the proposed scheme in an optimally controlled 2-DOF model of the arm for fast point-to-point shoulder and elbow movements. Simulations showed that the proposed feedback could be easily incorporated in the optimal control framework without complicating the computation of the optimal control solution, yet greatly enhancing the system's response to perturbations. The theoretical analyses in this study might furthermore provide insight about the strong physiological couplings found between muscle spindle and GTO afferents in the human nervous system.

  19. The Biomechanical Role of Scaffolds in Augmented Rotator Cuff Tendon Repairs

    DTIC Science & Technology

    2012-01-01

    ultimate load (56%-76%) of rotator cuff repairs in a human cadaver model.20 X-Repair augmentation also altered the mode of repair failure: failure by...amore clinically relevant repair and loading conditions in a human cadaver model: full-thickness supraspinatus tendon repairs (with and without...Andreychik D, Ahmad S. Determinants of outcome in the treatment of rotator cuff disease . Clin Orthop Rel Res 1994;308:90-7. 6. Bishop J, Klepps S, Lo IK

  20. Changes in Achilles tendon mechanical properties following eccentric heel drop exercise are specific to the free tendon.

    PubMed

    Obst, S J; Newsham-West, R; Barrett, R S

    2016-04-01

    Mechanical loading of the Achilles tendon during isolated eccentric contractions could induce immediate and region-dependent changes in mechanical properties. Three-dimensional ultrasound was used to examine the immediate effect of isolated eccentric exercise on the mechanical properties of the distal (free tendon) and proximal (gastrocnemii) regions of the Achilles tendon. Participants (n = 14) underwent two testing sessions in which tendon measurements were made at rest and during a 30% and 70% isometric plantar flexion contractions immediately before and after either: (a) 3 × 15 eccentric heel drops or (b) 10-min rest. There was a significant time-by-session interaction for free tendon length and strain for all loading conditions (P < 0.05). Pairwise comparisons revealed a significant increase in free tendon length and strain at all contraction intensities after eccentric exercise (P < 0.05). There was no significant time-by-session interaction for the gastrocnemii (medial or lateral) aponeurosis or tendon for any of the measured parameters. Immediate changes in Achilles tendon mechanical properties were specific to the free tendon and consistent with changes due to mechanical creep. These findings suggest that the mechanical properties of the free tendon may be more vulnerable to change with exercise compared with the gastrocnemii aponeurosis or tendon.

  1. Mineral Distributions at the Developing Tendon Enthesis

    PubMed Central

    Schwartz, Andrea G.; Pasteris, Jill D.; Genin, Guy M.; Daulton, Tyrone L.; Thomopoulos, Stavros

    2012-01-01

    Tendon attaches to bone across a functionally graded interface, “the enthesis”. A gradient of mineral content is believed to play an important role for dissipation of stress concentrations at mature fibrocartilaginous interfaces. Surgical repair of injured tendon to bone often fails, suggesting that the enthesis does not regenerate in a healing setting. Understanding the development and the micro/nano-meter structure of this unique interface may provide novel insights for the improvement of repair strategies. This study monitored the development of transitional tissue at the murine supraspinatus tendon enthesis, which begins postnatally and is completed by postnatal day 28. The micrometer-scale distribution of mineral across the developing enthesis was studied by X-ray micro-computed tomography and Raman microprobe spectroscopy. Analyzed regions were identified and further studied by histomorphometry. The nanometer-scale distribution of mineral and collagen fibrils at the developing interface was studied using transmission electron microscopy (TEM). A zone (∼20 µm) exhibiting a gradient in mineral relative to collagen was detected at the leading edge of the hard-soft tissue interface as early as postnatal day 7. Nanocharacterization by TEM suggested that this mineral gradient arose from intrinsic surface roughness on the scale of tens of nanometers at the mineralized front. Microcomputed tomography measurements indicated increases in bone mineral density with time. Raman spectroscopy measurements revealed that the mineral-to-collagen ratio on the mineralized side of the interface was constant throughout postnatal development. An increase in the carbonate concentration of the apatite mineral phase over time suggested possible matrix remodeling during postnatal development. Comparison of Raman-based observations of localized mineral content with histomorphological features indicated that development of the graded mineralized interface is linked to endochondral

  2. Mineral distributions at the developing tendon enthesis.

    PubMed

    Schwartz, Andrea G; Pasteris, Jill D; Genin, Guy M; Daulton, Tyrone L; Thomopoulos, Stavros

    2012-01-01

    Tendon attaches to bone across a functionally graded interface, "the enthesis". A gradient of mineral content is believed to play an important role for dissipation of stress concentrations at mature fibrocartilaginous interfaces. Surgical repair of injured tendon to bone often fails, suggesting that the enthesis does not regenerate in a healing setting. Understanding the development and the micro/nano-meter structure of this unique interface may provide novel insights for the improvement of repair strategies. This study monitored the development of transitional tissue at the murine supraspinatus tendon enthesis, which begins postnatally and is completed by postnatal day 28. The micrometer-scale distribution of mineral across the developing enthesis was studied by X-ray micro-computed tomography and Raman microprobe spectroscopy. Analyzed regions were identified and further studied by histomorphometry. The nanometer-scale distribution of mineral and collagen fibrils at the developing interface was studied using transmission electron microscopy (TEM). A zone (∼20 µm) exhibiting a gradient in mineral relative to collagen was detected at the leading edge of the hard-soft tissue interface as early as postnatal day 7. Nanocharacterization by TEM suggested that this mineral gradient arose from intrinsic surface roughness on the scale of tens of nanometers at the mineralized front. Microcomputed tomography measurements indicated increases in bone mineral density with time. Raman spectroscopy measurements revealed that the mineral-to-collagen ratio on the mineralized side of the interface was constant throughout postnatal development. An increase in the carbonate concentration of the apatite mineral phase over time suggested possible matrix remodeling during postnatal development. Comparison of Raman-based observations of localized mineral content with histomorphological features indicated that development of the graded mineralized interface is linked to endochondral

  3. Anatomic variation of the 5th extensor tendon compartment and extensor digiti minimi tendon.

    PubMed

    Tanaka, Toshikazu; Moran, Steven L; Zhao, Chunfeng; Zobitz, Mark E; An, Kai-Nan; Amadio, Peter C

    2007-08-01

    Anatomic variation within the 5th extensor compartment may contribute to the development of tenosynovitis and limit the usefulness of the extensor digiti minimi (EDM) for tendon transfer. The purpose of this study was to assess the anatomic variation of the EDM tendon and its surrounding retinaculum, with particular attention to anatomical variation between specimens. Forty-one fresh cadaver hands were dissected. The length of the 5th compartment retinaculum was noted. The incidence of an intercompartmental septum was noted in each specimen as well as the type of tendinous attachments present between the EDM and extensor digitorum communis (EDC) tendons. The presence and length of any accessory retinacular bands distal to the edge of proper extensor retinaculum was also noted. Only one specimen contained a single EDM tendon, while 71% (n = 29) of specimens contained two slips and 23% (n = 9) had three slips; 24% (n = 10) of EDC tendons had no slip to the small finger, while 61% (n = 25) of specimens had a single slip to the small finger. The EDC's contribution to the small finger was found to be an independent tendon in 42% of cases (n = 17), while 34% (n = 14) of specimens were found to have a common EDC slip, which branched to both the ring and small finger. Three EDM tendons divided distal to the extensor retinaculum, while the remaining EDM tendons divided beneath or proximal to the extensor retinaculum. Seventy-three percent (n = 30) of the specimens had an accessory retinacular band surrounding the EDM tendon identified at the base of the 5th metacarpal. Eighty-eight percent (n = 36) of hands had a septum between the EDM slips. The surgeon should be aware of variability within the 5th dorsal compartment in cases of trauma and in cases of tendon transfer. In our series 30 of 41 specimens were noted to contain an accessory dorsal retinacular band surrounding the EDM and 36 specimens were noted to contain a septum within the 5th compartment. The presence of an

  4. Simvastatin and atorvastatin reduce the mechanical properties of tendon constructs in vitro and introduce catabolic changes in the gene expression pattern

    PubMed Central

    Svensson, Rene B.; Giannopoulos, Antonis; Eismark, Christian; Kjær, Michael; Schjerling, Peter; Heinemeier, Katja M.

    2017-01-01

    Treatment with lipid-lowering drugs, statins, is common all over the world. Lately, the occurrence of spontaneous tendon ruptures or tendinosis have suggested a negative influence of statins upon tendon tissue. But how statins might influence tendons is not clear. In the present study, we investigated the effect of statin treatment on mechanical strength, cell proliferation, collagen content and gene expression pattern in a tendon-like tissue made from human tenocytes in vitro. Human tendon fibroblasts were grown in a 3D tissue culture model (tendon constructs), and treated with either simvastatin or atorvastatin, low or high dose, respectively, for up to seven days. After seven days of treatment, mechanical testing of the constructs was performed. Collagen content and cell proliferation were also determined. mRNA levels of several target genes were measured after one or seven days. The maximum force and stiffness were reduced by both statins after 7 days (p<0.05), while the cross sectional area was unaffected. Further, the collagen content was reduced by atorvastatin (p = 0.01) and the cell proliferation rate was decreased by both types of statins (p<0.05). Statin treatment also introduced increased mRNA levels of MMP-1, MMP-3, MMP-13, TIMP-1 and decreased levels of collagen type 1 and 3. In conclusion, statin treatment appears to have a negative effect on tendon matrix quality as seen by a reduced strength of the tendon constructs. Further, activated catabolic changes in the gene expression pattern and a reduced collagen content indicated a disturbed balance in matrix production of tendon due to statin administration. PMID:28264197

  5. Effect of tendon tensioning: an in vitro study in porcine extensor tendons.

    PubMed

    Figueroa, David; Calvo, Rafael; Vaisman, Alex; Meleán, Patricio; Figueroa, Francisco

    2010-06-01

    Graft tensioning is a controversial issue in anterior cruciate ligament reconstruction (ACLR) that has not achieved consensus between peers. The purpose of this study is to determine if after tensioning tendon length and resistance to maximal load changes. We performed an in vitro study with 50 porcine extensors tendons. The first group (P=25) was tensioned with 80 N (19.97 lb) for 10 min, using an ACL graft preparation board. The second group (C=25) was used as control and was not tensioned. The average initial (groups P and C) and post tensioning tendon length (group C) were measured; the average initial and post tensioning tendon diameter were measured as well. All samples were fixated in a tube-clamp system connected to a tension sensor. The samples were stressed with continuous and progressive tension until ultimate failure at maximum load (UFML) occurs. The initial mean length was: P before tensioning=13.4 mm+/-1.4 mm (range 10.5-16.5); P after tensioning=13.8 mm+/-1.4 mm (range 11.5-16.5); C=13 mm+/-1.35 mm (p=0.005). The mean diameter was: P=5.6 mm (4.5-6); C=5.5 mm (range 4.5-6) (p>0.05). The UFML was: P=189.7 N (114-336); C=229.9 N (143-365) (p=0.029). Tendon tensioning with 80 N for 10 min produced 3% average elongation. These could be beneficial in ACLR since tendon tensioning decreases elongation of the graft after fixation. Regardless, tendon tensioning is not innocuous since it diminishes their resistance when continuously stressed until complete failure occurs.

  6. Flexor tendon injuries. Part 5. Flexor tenolysis, rehabilitation and results.

    PubMed

    Strickland, J W

    1987-03-01

    In this five-part series, we have attempted to review our current understanding of flexor tendon anatomy, physiology, biomechanics, healing and adhesion formation around a repaired tendon. The methods of acute flexor tendon repair, conventional free tendon grafting, staged flexor tendon reconstruction and pulley restoration have been discussed as well as flexor tenolysis, rehabilitation and results. From these articles it may be seen that flexor tendon surgery is a complex and difficult art which requires a thorough appreciation of the normal flexor tendon system, the exact status of that system following injury and a strong understanding of the techniques which may be best utilized to restore flexor tendon function. The procedures described require both technical skill and experience and postoperative therapy programs must be carefully instituted based on the unique status of each patient. With the important advances occurring in many areas of flexor tendon surgery, it is realistic to believe that in the near future the techniques described in these articles may be substantially altered and modified. Results will continue to improve until the patient and surgeon can realistically expect to return most digits to nearly full function after flexor tendon interruption.

  7. The Cellular Biology of Flexor Tendon Adhesion Formation

    PubMed Central

    Wong, Jason K.F.; Lui, Yin H.; Kapacee, Zoher; Kadler, Karl E.; Ferguson, Mark W. J.; McGrouther, Duncan A.

    2009-01-01

    Intrasynovial flexor tendon injuries of the hand can frequently be complicated by tendon adhesions to the surrounding sheath, limiting finger function. We have developed a new tendon injury model in the mouse to investigate the three-dimensional cellular biology of intrasynovial flexor tendon healing and adhesion formation. We investigated the cell biology using markers for inflammation, proliferation, collagen synthesis, apoptosis, and vascularization/myofibroblasts. Quantitative immunohistochemical image analysis and three-dimensional reconstruction with cell mapping was performed on labeled serial sections. Flexor tendon adhesions were also assessed 21 days after wounding using transmission electron microscopy to examine the cell phenotypes in the wound. When the tendon has been immobilized, the mouse can form tendon adhesions in the flexor tendon sheath. The cell biology of tendon healing follows the classic wound healing response of inflammation, proliferation, synthesis, and apoptosis, but the greater activity occurs in the surrounding tissue. Cells that have multiple “fibripositors” and cells with cytoplasmic protrusions that contain multiple large and small diameter fibrils can be found in the wound during collagen synthesis. In conclusion, adhesion formation occurs due to scarring between two damaged surfaces. The mouse model for flexor tendon injury represents a new platform to study adhesion formation that is genetically tractable. PMID:19834058

  8. Decellularized and Engineered Tendons as Biological Substitutes: A Critical Review

    PubMed Central

    Lovati, Arianna B.; Bottagisio, Marta; Moretti, Matteo

    2016-01-01

    Tendon ruptures are a great burden in clinics. Finding a proper graft material as a substitute for tendon repair is one of the main challenges in orthopaedics, for which the requirement of a biological scaffold would be different for each clinical application. Among biological scaffolds, the use of decellularized tendon-derived matrix increasingly represents an interesting approach to treat tendon ruptures. We analyzed in vitro and in vivo studies focused on the development of efficient protocols for the decellularization and for the cell reseeding of the tendon matrix to obtain medical devices for tendon substitution. Our review considered also the proper tendon source and preclinical animal models with the aim of entering into clinical trials. The results highlight a wide panorama in terms of allogenic or xenogeneic tendon sources, specimen dimensions, physical or chemical decellularization techniques, and the cell type variety for reseeding from terminally differentiated to undifferentiated mesenchymal stem cells and their static or dynamic culture employed to generate implantable constructs tested in different animal models. We try to identify the most efficient approach to achieve an optimal biological scaffold for biomechanics and intrinsic properties, resembling the native tendon and being applicable in clinics in the near future, with particular attention to the Achilles tendon substitution. PMID:26880985

  9. Crimp morphology in relaxed and stretched rat Achilles tendon.

    PubMed

    Franchi, Marco; Fini, Milena; Quaranta, Marilisa; De Pasquale, Viviana; Raspanti, Mario; Giavaresi, Gianluca; Ottani, Vittoria; Ruggeri, Alessandro

    2007-01-01

    Fibrous extracellular matrix of tendon is considered to be an inextensible anatomical structure consisting of type I collagen fibrils arranged in parallel bundles. Under polarized light microscopy the collagen fibre bundles appear crimped with alternating dark and light transverse bands. This study describes the ultrastructure of the collagen fibrils in crimps of both relaxed and in vivo stretched rat Achilles tendon. Under polarized light microscopy crimps of relaxed Achilles tendons appear as isosceles or scalene triangles of different size. Tendon crimps observed via SEM and TEM show the single collagen fibrils that suddenly change their direction containing knots. The fibrils appear partially squeezed in the knots, bent on the same plane like bayonets, or twisted and bent. Moreover some of them lose their D-period, revealing their microfibrillar component. These particular aspects of collagen fibrils inside each tendon crimp have been termed 'fibrillar crimps' and may fulfil the same functional role. When tendon is physiologically stretched in vivo the tendon crimps decrease in number (46.7%) (P<0.01) and appear more flattened with an increase in the crimp top angle (165 degrees in stretched tendons vs. 148 degrees in relaxed tendons, P<0.005). Under SEM and TEM, the 'fibrillar crimps' are still present, never losing their structural identity in straightened collagen fibril bundles of stretched tendons even where tendon crimps are not detectable. These data suggest that the 'fibrillar crimp' may be the true structural component of the tendon crimp acting as a shock absorber during physiological stretching of Achilles tendon.

  10. Cryotherapy suppresses tendon inflammation in an animal model

    PubMed Central

    Zhang, Jianying; Pan, Tiffany; Wang, James H.-C.

    2015-01-01

    Summary Cryotherapy (or cold treatment) has been a popular treatment to relieve pain caused by injuries to tissues such as tendons. However, the exact mechanisms behind the beneficial effects of cryotherapy in tendons remain largely unclear. As prostaglandin E2 (PGE2) is known to be a major mediator of acute inflammation in tissues, which is related to tissue pain, we hypothesized that the beneficial effects of cryotherapy in tendons are mediated by downregulation of PGE2 levels. To test this hypothesis, we applied cold treatment to mouse patellar and Achilles tendons using two animal models: exhaustive mouse treadmill running and acute mouse tendon injury by needle penetration. We then measured the levels of PGE2 and protein expression levels of COX-2, an enzyme responsible for PGE2 production in tissues, under both experimental conditions. We found that treadmill running increased PGE2 levels in both patellar and Achilles tendons compared to control mice without running. Cold treatment for 30 min after treadmill running was sufficient to reduce PGE2 levels to near baseline control levels in both tendons. An extension of cold treatment to 60 min resulted only in a marginal decrease in patellar tendons, but a marked decrease in Achilles tendons. Moreover, COX-2 protein levels in both tendons were also lowered by cold treatment, suggesting that the reduction of PGE2 levels in tendons by cold treatment is at least in part due to the decreased COX-2 expression. Similarly, in the acutely injured tendons, 30 min of cold treatment after needle penetration reduced PGE2 levels when compared to the controls at room temperature (22°C). This decrease was sustained up to at least 3 h after the administration of cryotherapy. Given that PGE2 is a known pain sensitiser, the results of this study suggest that the ability of cold treatment to reduce pain may be attributable to its ability to decrease PGE2 production in tendons. PMID:26594634

  11. Effects of prolonged patellar tendon vibration on force steadiness in quadriceps femoris during force-matching task.

    PubMed

    Saito, Akira; Ando, Ryosuke; Akima, Hiroshi

    2016-01-01

    The quadriceps femoris (QF) muscle group plays an essential role in human movement, such as standing, walking and running. The ability to maintain a steady force during physical activity of the human lower limb is important for mobility, postural control and balance. Although prolonged mechanical vibration of the muscle-tendon unit can moderate the efficacy of synaptic input from Ia afferent onto the α-motor neuron pathway, the effect of prolonged tendon vibration on fluctuations of knee extensor force has received little attention. The purpose of the present study was to examine the effects of prolonged patellar tendon vibration on the force steadiness of the QF muscle. Nine healthy men performed a submaximal force-matching task involving isometric knee extension before and after patellar tendon vibration or quiet seated rest (n = 7, control condition) for 30 min. The target force was 2.5, 10 and 30 % of maximal voluntary contraction (MVC). Surface electromyography (EMG) of the four QF synergists was recorded and normalized to EMG amplitude during the MVC. The knee extension force and the EMG amplitude of vastus medialis during the MVC were significantly reduced after the vibration, but did not significantly decrease in the control condition. Fluctuations of force and normalized EMG of individual QF muscles at each submaximal force level did not significantly change after the vibration. We conclude that prolonged patellar tendon vibration does not influence the force steadiness of the QF muscle during an isometric force-matching task.

  12. Gliding resistance of flexor tendon associated with carpal tunnel pressure: a biomechanical cadaver study.

    PubMed

    Zhao, Chunfeng; Ettema, Anke M; Berglund, Lawrence J; An, Kai-Nan; Amadio, Peter C

    2011-01-01

    The purpose of this study was to investigate the effect of carpal tunnel pressure on the gliding characteristics of flexor tendons within the carpal tunnel. Eight fresh human cadaver wrists and hands were used. A balloon was inserted into the carpal tunnel to elevate the pressure. The mean gliding resistance of the middle finger flexor digitorum superficialis tendon was measured with the following six conditions: (1) as a baseline, before balloon insertion; (2) balloon with 0 mmHg pressure; (3) 30 mmHg; (4) 60 mmHg; (5) 90 mmHg; (6) 120 mmHg. The gliding resistance of flexor tendon gradually increased as the carpal tunnel pressure was elevated. At pressures above 60 mmHg, the increase in gliding resistance became significant compared to the baseline condition. This study helps us to understand the relationship between carpal tunnel pressure, which is elevated in the patient with carpal tunnel syndrome (CTS) and tendon gliding resistance, which is a component of the work of flexion. These findings suggest that patients with CTS may have to expend more energy to accomplish specific motions, which may in turn affect symptoms of hand pain, weakness and fatigue, seen commonly in such patients.

  13. Gliding characteristics between flexor tendons and surrounding tissues in the carpal tunnel: a biomechanical cadaver study.

    PubMed

    Zhao, Chunfeng; Ettema, Anke M; Osamura, Naoki; Berglund, Lawrence J; An, Kai-Nan; Amadio, Peter C

    2007-02-01

    The purpose of this study was to investigate the gliding characteristics of flexor tendons within the carpal tunnel with varied wrist positions and tendon motion styles, which may help us to understand the relationship between carpal tunnel syndrome (CTS) and repetitive hand motion. Eight fresh human cadaveric wrists and hands were used. The peak (PGR) and mean (MGR) gliding resistance of the middle finger flexor digitorum superficialis tendon were measured with the wrist in 0, 30, and 60 degrees of flexion and extension. While moving all three fingers together, the PGR at 60 degrees flexion was significantly higher than that at 0, 30, or 60 degrees extension. While moving the middle finger alone, the PGR at 60 and 30 degrees flexion was significantly higher than the PGR at 60 degrees extension. The PGR moving the middle finger FDS alone was significantly greater than that for all three digits moving together in 0, 30, and 60 degrees flexion. Differential finger motion with wrist flexion elevated the tendon gliding resistance in the carpal tunnel, which may be relevant in considering the possible role of wrist position and activity in the etiology of CTS.

  14. Anisotropy of the transverse mode ultrasonic properties of fixed tendon and fixed myocardium.

    PubMed

    Hoffmeister, B K; Gehr, S E; Miller, J G

    1996-06-01

    This study investigates the influence of the fiber-reinforced nature of myocardium and tendon on the propagation of transverse mode ultrasonic waves. Formalin fixed specimens of normal human left ventricular cardiac muscle and bovine Achilles tendon were prepared for this study in such a way that transverse mode ultrasonic waves could be propagated perpendicular to the fiber axis of the tissue with the polarization oriented either parallel or perpendicular to the fiber axis. Measurements of velocity and attenuation were made at 3 MHz to assess the degree of anisotropy in these parameters for both tissues. Formalin fixed tendon exhibited a significant anisotropy whereas formalin fixed myocardium displayed a similar trend of more modest magnitude. Results of these measurements were used to compute two elastic stiffness coefficients for each tissue, yielding c44 = 37.2 MPa and c66 = 18.0 MPa for formalin fixed tendon, and c44 = 8.97 MPa and c66 = 8.45 MPa for formalin fixed myocardium. To validate this approach, additional studies were conducted to measure the transverse mode ultrasonic properties of silicone rubber and motor oil.

  15. Peritendinous elastase treatment induces tendon degeneration in rats: A potential model of tendinopathy in vivo.

    PubMed

    Wu, Yen-Ting; Wu, Po-Ting; Jou, I-Ming

    2016-03-01

    The purpose of this study was to investigate the role of elastase on tendinopathy, as well as to evaluate the potential for peritendinous injections of elastase into rats to cause tendinopathy. We first investigated the expression of elastase in the tendons of patients with tendinopathy, and then established the effects of elastase injection on the Achilles tendons of rats. Ultrasonographic and incapacitance testing was used to conduct tests for 8 weeks. Tendon tissues were collected for histological observation and protein levels of collagen type I and type III were detected using Western blotting. The percentage of elastase-positive cells increased in human specimens with grades II and III tendinopathy. The rat model demonstrated that the thickness of the tendon increased after elastase injection during Week 2-8. Hypercellularity and focal lesions were detected after Week 2. The expression of elastase was increased and elastin was decreased in Week 8. Collagen type I expression was decreased, but type III was increased in Week 4. These results suggested that elastase may be involved in the development of chronic tendinopathy, and that peritendinous injection of elastase may result in tendinopathy in rats.

  16. Development of a mouse model of supraspinatus tendon insertion site healing.

    PubMed

    Bell, Rebecca; Taub, Peter; Cagle, Paul; Flatow, Evan L; Andarawis-Puri, Nelly

    2015-01-01

    Supraspinatus (SS) tendon tears are common musculoskeletal injuries whose surgical repair exhibits the highest incidence of re-tear of any tendon. Development of therapeutics for improving SS tendon healing is impaired by the lack of a model that allows biological perturbations to identify mechanisms that underlie ineffective healing. The objective of this study was to develop a mouse model of supraspinatus insertion site healing by creating a reproducible SS tendon detachment and surgical repair which can be applied to a wide array of inbred mouse strains and genetic mutants. Anatomical and structural analyses confirmed that the rotator cuff of the mouse is similar to that of human, including the presence of a coracoacromial (CA) arch and an insertion site that exhibits a fibrocartilagenous transition zone. The surgical repair was successfully conducted on seven strains of mice that are commonly used in Orthopaedic Research suggesting that the procedure can be applied to most inbred strains and genetic mutants. The quality of the repair was confirmed with histology through 14 days after surgery in two mouse strains that represent the variation in mouse strains evaluated. The developed mouse model will allow us to investigate mechanisms involved in insertion site healing.

  17. LRT, a tendon-specific leucine-rich repeat protein, promotes muscle-tendon targeting through its interaction with Robo.

    PubMed

    Wayburn, Bess; Volk, Talila

    2009-11-01

    Correct muscle migration towards tendon cells, and the adhesion of these two cell types, form the basis for contractile tissue assembly in the Drosophila embryo. While molecules promoting the attraction of muscles towards tendon cells have been described, signals involved in the arrest of muscle migration following the arrival of myotubes at their corresponding tendon cells have yet to be elucidated. Here, we describe a novel tendon-specific transmembrane protein, which we named LRT due to the presence of a leucine-rich repeat domain (LRR) in its extracellular region. Our analysis suggests that LRT acts non-autonomously to better target the muscle and/or arrest its migration upon arrival at its corresponding tendon cell. Muscles in embryos lacking LRT exhibited continuous formation of membrane extensions despite arrival at their corresponding tendon cells, and a partial failure of muscles to target their correct tendon cells. In addition, overexpression of LRT in tendon cells often stalled muscles located close to the tendon cells. LRT formed a protein complex with Robo, and we detected a functional genetic interaction between Robo and LRT at the level of muscle migration behavior. Taken together, our data suggest a novel mechanism by which muscles are targeted towards tendon cells as a result of LRT-Robo interactions. This mechanism may apply to the Robo-dependent migration of a wide variety of cell types.

  18. Increased unilateral tendon stiffness and its effect on gait 2-6 years after Achilles tendon rupture.

    PubMed

    Agres, A N; Duda, G N; Gehlen, T J; Arampatzis, A; Taylor, W R; Manegold, S

    2015-12-01

    Achilles tendon rupture (ATR) alters tissue composition, which may affect long-term tendon mechanics and ankle function during movement. However, a relationship between Achilles tendon (AT) properties and ankle joint function during gait remains unclear. The primary hypotheses were that (a) post-ATR tendon stiffness and length differ from the noninjured contralateral side and that (b) intra-patient asymmetries in AT properties correlate to ankle function asymmetries during gait, determined by ankle angles and moments. Ultrasonography and dynamometry were used to assess AT tendon stiffness, strain, elongation, and rest length in both limbs of 20 ATR patients 2-6 years after repair. Three-dimensional ankle angles and moments were determined using gait analysis. Injured tendons exhibited increased stiffness, rest length, and altered kinematics, with higher dorsiflexion and eversion, and lower plantarflexion and inversion. Intra-patient tendon stiffness and tendon length ratios were negatively correlated to intra-patient ratios of the maximum plantarflexion moment and maximum dorsiflexion angle, respectively. These results suggest that after surgical ATR repair, higher AT stiffness, but not a longer AT, may contribute to deficits in plantarflexion moment generation. These data further support the claim that post-ATR tendon regeneration results in the production of a tissue that is functionally different than noninjured tendon.

  19. Bifurcated intraarticular long head of biceps tendon

    PubMed Central

    Pandey, Vivek; van Laarhoven, Simon Nurettin; Arora, Gaurav; Rao, Sripathi

    2014-01-01

    Though rare, many anomalous origins of long head of the biceps tendon (LHBT) have been reported in the literature. Anatomic variations commonly explained are a third humeral head, anomalous insertion, congenital absence and adherence to the rotator cuff. We report a rare case who underwent shoulder arthroscopy with impingement symptoms where in LHBT was found to be bifurcated with a part attached to superior labrum and the other part to the posterior capsule of joint. Furthermore, intraarticular portion of LHBT was adherent to the undersurface of the supraspinatus tendon. Awareness of such an anatomical aberration during the shoulder arthroscopy is of great importance as it can potentially avoid unnecessary confusion and surgery. PMID:25143652

  20. Chronic Achilles Tendon Rupture Treated with Allograft: A Case Report.

    PubMed

    Restuccia, Giuseppe; Lippi, Alessandro; Casella, Francesco; Citarelli, Carmine; Sacchetti, Federico; Benifei, Maurizio

    2017-02-07

    In clinical practice, chronic Achilles tendon ruptures are uncommon. Usually, these lesions are discovered four to six weeks after injuries. More frequently, Achilles tendon ruptures are acute and treated with tendon sutures.1 Many surgical techniques are available to treat chronic lesions such as sutures or V-Y elongation with or without augments.2-3 Our case is about a chronic Achilles tendon rupture discovered two years after injury. Our patient came to our attention with a 6 cm tendon gap. We performed tendon repair with cadaver allograft. After four years of follow-up, our patient has a complete functional recovery and he can normally perform daily and working tasks without pain.

  1. Towards inference of human brain connectivity from MR diffusion tensor data.

    PubMed

    Poupon, C; Mangin, J; Clark, C A; Frouin, V; Régis, J; Le Bihan, D; Bloch, I

    2001-03-01

    This paper describes a method to infer the connectivity induced by white matter fibers in the living human brain. This method stems from magnetic resonance tensor imaging (DTI), a technique which gives access to fiber orientations. Given typical DTI spatial resolution, connectivity is addressed at the level of fascicles made up by a bunch of parallel fibers. We propose first an algorithm dedicated to fascicle tracking in a direction map inferred from diffusion data. This algorithm takes into account fan-shaped fascicle forks usual in actual white matter organization. Then, we propose a method of inferring a regularized direction map from diffusion data in order to improve the robustness of the tracking. The regularization stems from an analogy between white matter organization and spaghetti plates. Finally, we propose a study of the tracking behavior according to the weight given to the regularization and some examples of the tracking results with in vivo human brain data.

  2. Surgical Management of Fractures and Tendons.

    PubMed

    Pentecost, Rebecca; Niehaus, Andrew J; Anderson, David E

    2016-11-01

    Long bone fractures and disorders of tendons and ligaments represent a significant proportion of surgical orthopedic cases presented to ruminant veterinarians. The presentation of these patients, their diagnostic work-up, surgical treatment, and expected outcome will be discussed. The outcome of these cases depends largely on the presenting problem; however, accurate diagnosis and prompt surgical intervention can greatly improve the outcome of many of these cases.

  3. Rat Achilles tendon healing: mechanical loading and gene expression.

    PubMed

    Eliasson, Pernilla; Andersson, Therese; Aspenberg, Per

    2009-08-01

    Injured tendons require mechanical tension for optimal healing, but it is unclear which genes are upregulated and responsible for this effect. We unloaded one Achilles tendon in rats by Botox injections in the calf muscles. The tendon was then transected and left to heal. We studied mechanical properties of the tendon calluses, as well as mRNA expression, and compared them with loaded controls. Tendon calluses were studied 3, 8, 14, and 21 days after transection. Intact tendons were studied similarly for comparison. Altogether 110 rats were used. The genes were chosen for proteins marking inflammation, growth, extracellular matrix, and tendon specificity. In intact tendons, procollagen III and tenascin-C were more expressed in loaded than unloaded tendons, but none of the other genes was affected. In healing tendons, loading status had small effects on the selected genes. However, TNF-alpha, transforming growth factor-beta1, and procollagens I and III were less expressed in loaded callus tissue at day 3. At day 8 procollagens I and III, lysyl oxidase, and scleraxis had a lower expression in loaded calluses. However, by days 14 and 21, procollagen I, cartilage oligomeric matrix protein, tenascin-C, tenomodulin, and scleraxis were all more expressed in loaded calluses. In healing tendons, the transverse area was larger in loaded samples, but material properties were unaffected, or even impaired. Thus mechanical loading is important for growth of the callus but not its mechanical quality. The main effect of loading during healing might thereby be sought among growth stimulators. In the late phase of healing, tendon-specific genes (scleraxis and tenomodulin) were upregulated with loading, and the healing tissue might to some extent represent a regenerate rather than a scar.

  4. Extensor tendon ruptures after total knee arthroplasty.

    PubMed

    Bonnin, M; Lustig, S; Huten, D

    2016-02-01

    Extensor tendon rupture is a rare but serious complication after total knee arthroplasty (TKA) that impairs active knee extension, thereby severely affecting knee function. Surgery is usually required. Surgical options range from simple suturing to allograft reconstruction of the entire extensor mechanism and include intermediate methods such as reconstruction using neighbouring tendons or muscles, synthetic ligament implantation, and partial allograft repair. Simple suturing carries a high failure rate and should therefore be routinely combined with tissue augmentation using a neighbouring tendon or a synthetic ligament. After allograft reconstruction, outcomes are variable and long-term complications common. Salvage procedures for managing the most severe cases after allograft failure involve reconstruction using gastrocnemius or vastus flaps. Regardless of the technique used, suturing must be performed under tension, with the knee fully extended, and rehabilitation must be conducted with great caution. Weaknesses of available case-series studies include small sample sizes, heterogeneity, and inadequate follow-up duration. All treatment options are associated with substantial failure rates. The patient should be informed of this fact and plans made for a salvage option. Here, the main techniques and their outcomes are discussed, and a therapeutic strategy is suggested.

  5. Low level laser therapy in healing tendon

    NASA Astrophysics Data System (ADS)

    Carvalho, P. T. C.; Batista, Cheila O. C.; Fabíola, C.

    2005-11-01

    This study aims to verify the effects of AsGa Laser in the scarring of tendon lesion in rats with low nourishment condition and to analyze the ideal light density by means of histopathologic findings highlighted by light microscopy. After the proposed nutritional condition was verified the animals were divided into 3 groups denominated as follows: GI control group, GII laser 1 J/sq.cm. and GIII laser 4 J/sq.cm. The lesions were induced by means of routine surgical process for tendon exposure: There was a crushing process with Allis pincers followed by saturated incision. The data obtained in relation to the amount of macrophage, leukocyte, fibroblast, vessel neoformation, fibrosis and collagen were submitted to parametric statistic procedures of variance analysis and "Tukey" Test and the result obtained was p < 0,05. According to the obtained results it can be concluded that low power laser therapy proved to be efficient in tendon repairing even though the animals suffered from malnutrition as well as the 1 J energy density proved to be more efficient in this case.

  6. Retropharyngeal calcific tendonitis: report of two cases.

    PubMed

    Razon, Rhea Victoria B; Nasir, Asad; Wu, George S; Soliman, Manal; Trilling, Jeffrey

    2009-01-01

    Retropharyngeal calcific tendonitis is an inflammatory process of the superior oblique tendons of the longus colli muscle, a neck flexor in the upper cervical spine, caused by deposition of calcium hydroxyapatite crystals; the definitive diagnostic test is computed tomography (CT). Presented in this article are two cases seen at our institution. Patients typically present with acute onset of neck pain/spasm, odynophagia, dysphagia, and/or low grade fevers. Leukocytosis and elevated erythrocyte sedimentation rate may be noted. It is important to understand this entity because its signs and symptoms are mimickers of those of the more serious condition of retropharyngeal space abscess. Calcific tendonitis is managed conservatively whereas retropharyngeal abscess requires incision and drainage. Some may argue that this entity is a zebra because its reported incidence in the literature is low. However, most of these studies were done in an era when CT was not yet in vogue. With today's widespread use of CT and its superb ability to visualize the calcification, the true incidence of this condition is probably higher and, thus, it is important for the family practitioner to be aware of this entity. The astute clinician may save the patient from unnecessary diagnostic workup, undue anxiety, and delays in hospital discharge.

  7. An Artificial Tendon with Durable Muscle Interface

    PubMed Central

    Melvin, Alan; Litsky, Alan; Mayerson, Joel; Witte, David; Melvin, David; Juncosa-Melvin, Natalia

    2010-01-01

    A coupling mechanism that can permanently fix a forcefully contracting muscle to a bone anchor or any totally inert prosthesis would meet a serious need in orthopaedics. Our group developed the OrthoCoupler™ device to satisfy these demands. The objective of this study was to test OrthoCoupler’s performance in vitro and in vivo in the goat semitendinosus tendon model. For in vitro evaluation, 40 samples were fatigue-tested, cycling at 10 load levels, n=4 each. For in vivo evaluation, the semitendinosus tendon was removed bilaterally in 8 goats. Left sides were reattached with an OrthoCoupler, and right sides were reattached using the Krackow stitch with #5 braided polyester sutures. Specimens were harvested 60 days post-surgery and assigned for biomechanics and histology. Fatigue strength of the devices in vitro was several times the contractile force of the semitendinosus muscle. The in vivo devices were built equivalent to two of the in vitro devices, providing an additional safety factor. In strength testing at necropsy, suture controls pulled out at 120.5 ± 68.3 N, whereas each OrthoCoupler was still holding after the muscle tore, remotely, at 298±111.3N (mean ± SD)(p<0.0003). Muscle tear strength was reached with the fiber-muscle composite produced in healing still soundly intact. This technology may be of value for orthopaedic challenges in oncology, revision arthroplasty, tendon transfer, and sports-injury reconstruction. PMID:19639642

  8. Use of the semitendinosus tendon for foot and ankle tendon reconstructions☆☆☆

    PubMed Central

    Lutti Guerra de Aguiar Zink, Frederico; Glória Mendonça, Danilo; Kelly Bittar, Cintia; Luís Amim Zabeu, José; Salomão, Osny; Egydio de Carvalho Junior, Antonio; Tarso Torquato, Marcelo; Cerqueira de Moraes Filho, Décio

    2014-01-01

    Objective To demonstrate the results obtained from foot and ankle tendon reconstructions using the tendon of the semitendinosus muscle. The clinical results, the patient's degree of satisfaction and complications in the graft donor and recipient areas were evaluated. Methods This was a retrospective study in which the medical files of 38 patients who underwent this surgical procedure between 2006 and 2010 were surveyed. The functional results from this technique, the complications in the donor and recipient areas and the patients’ degree of satisfaction were evaluated. Results Three patients presented complications in the recipient area (skin necrosis); one patient showed complications in the donor area (pain and insensitivity); and all patients had satisfactory functional results, with complete range of motion. Conclusion The semitendinosus muscle is a good option for treatments for foot and ankle tendon injuries. PMID:26229856

  9. Nanoparticles for Tendon Healing and Regeneration: Literature Review

    PubMed Central

    Parchi, Paolo D.; Vittorio, Orazio; Andreani, Lorenzo; Battistini, Pietro; Piolanti, Nicola; Marchetti, Stefano; Poggetti, Andrea; Lisanti, Michele

    2016-01-01

    Tendon injuries are commonly met in the emergency department. Unfortunately, tendon tissue has limited regeneration potential and usually the consequent formation of scar tissue causes inferior mechanical properties. Nanoparticles could be used in different way to improve tendon healing and regeneration, ranging from scaffolds manufacturing (increasing the strength and endurance or anti-adhesions, anti-microbial, and anti-inflammatory properties) to gene therapy. This paper aims to summarize the most relevant studies showing the potential application of nanoparticles for tendon tissue regeneration. PMID:27597828

  10. Tendon synovial cells secrete fibronectin in vivo and in vitro

    SciTech Connect

    Banes, A.J.; Link, G.W.; Bevin, A.G.; Peterson, H.D.; Gillespie, Y.; Bynum, D.; Watts, S.; Dahners, L.

    1988-01-01

    The chemistry and cell biology of the tendon have been largely overlooked due to the emphasis on collagen, the principle structural component of the tendon. The tendon must not only transmit the force of muscle contraction to bone to effect movement, but it must also glide simultaneously over extratendonous tissues. Fibronectin is classified as a cell attachment molecule that induces cell spreading and adhesion to substratum. The external surface of intact avian flexor tendon stained positively with antibody to cellular fibronectin. However, if the surface synovial cells were first removed with collagenase, no positive reaction with antifibronectin antibody was detected. Analysis of immunologically stained frozen sections of tendon also revealed fibronectin at the tendon synovium, but little was associated with cells internal in tendon. The staining pattern with isolated, cultured synovial cells and fibroblasts from the tendon interior substantiated the histological observations. Analysis of polyacrylamide gel profiles of /sup 35/S-methionine-labeled proteins synthesized by synovial cells and internal fibroblasts indicated that fibronectin was synthesized principally by synovial cells. Fibronectin at the tendon surface may play a role in cell attachment to prevent cell removal by the friction of gliding. Alternatively, fibronectin, with its binding sites for hyaluronic acid and collagen, may act as a complex for boundary lubrication.

  11. Multiple variations of the tendons of the anatomical snuffbox

    PubMed Central

    Thwin, San San; Zaini, Fazlin; Than, Myo

    2014-01-01

    INTRODUCTION Multiple tendons of the abductor pollicis longus (APL) in the anatomical snuffbox of the wrist can lead to the development of de Quervain's syndrome, which is caused by stenosing tenosynovitis. A cadaveric study was performed to establish the variations present in the tendons of the anatomical snuffbox in a Malaysian population, in the hope that this knowledge would aid clinical investigation and surgical treatment of de Quervain's tenosynovitis. METHODS Routine dissection of ten upper limbs was performed to determine the variations in the tendons of the anatomical snuffbox of the wrist. RESULTS In all the dissected upper limbs, the APL tendon of the first extensor compartment was found to have several (3–14) tendon slips. The insertion of the APL tendon slips in all upper limbs were at the base of the first metacarpal bone, trapezium and fascia of the opponens pollicis muscle; however, in seven specimens, they were also found to be attached to the fleshy belly of the abductor pollicis brevis muscle. In two specimens, double tendons of the extensor pollicis longus located in the third extensor compartment were inserted into the capsule of the proximal interphalangeal joints before being joined to the extensor expansion. In two other specimens, the first extensor compartment had two osseofibrous tunnels divided by a septum that separated the APL tendon from the extensor pollicis brevis tendon. CONCLUSION Multiple variations were found in the anatomical snuffbox region of the dissected upper limbs. Knowledge of these variations would be useful in interventional radiology and orthopaedic surgery. PMID:24452976

  12. Mechanical characteristics of native tendon slices for tissue engineering scaffold

    PubMed Central

    Qin, Ting-Wu; Chen, Qingshan; Sun, Yu-Long; Steinmann, Scott P.; Amadio, Peter C.; An, Kai-Nan; Zhao, Chunfeng

    2014-01-01

    The purpose of this study was to characterize the mechanical behavior of tendon slices with different thicknesses. Tendon slices of 100, 200, 300, 400, and 500 μm thickness were mechanically tested. The 300 μm slices were further tested for strength and modulus after 21,000-cycle fatigue testing under different applied strain levels (0, 1, 3, 5, 8, 10, and 12%). The tendon slice structure, morphology, and viability of bone marrow stromal cells (BMSCs) seeded onto the slices were also examined with histology, scanning electron microscopy, and vital cell labeling, respectively. Tendon slices 300 μm or more in thickness had similar ultimate tensile strength and Young's modulus to the intact tendon bundle. A strain of 5% or less did not cause any structural damage, nor did it change the mechanical properties of a 300 μm-thick tendon slice after 21,000-cycle fatigue testing. BMSCs were viable between and on the tendon slices after 2 weeks in tissue culture. This study demonstrated that, if tendon slices are used as a scaffold for tendon tissue engineering, slices 300 μm or more in thickness would be preferable from a mechanical strength point of view. If mechanical stimulation is performed for seeded-cell preparations, 5% strain or less would be appropriate. PMID:22323314

  13. Compression therapy promotes proliferative repair during rat Achilles tendon immobilization.

    PubMed

    Schizas, Nikos; Li, Jian; Andersson, Therese; Fahlgren, Anna; Aspenberg, Per; Ahmed, Mahmood; Ackermann, Paul W

    2010-07-01

    Achilles tendon ruptures are treated with an initial period of immobilization, which obstructs the healing process partly by a reduction of blood circulation. Intermittent pneumatic compression (IPC) has been proposed to enhance tendon repair by stimulation of blood flow. We hypothesized that daily IPC treatment can counteract the deficits caused by 2 weeks of immobilization post tendon rupture. Forty-eight Sprague-Dawley SD) rats, all subjected to blunt Achilles tendon transection, were divided in three equal groups. Group A was allowed free cage activity, whereas groups B-C were immobilized at the operated hindleg. Group C received daily IPC treatment. Two weeks postrupture the rats were euthanatized and the tendons analyzed with tensile testing and histological assessments of collagen organization and collagen III-LI occurrence. Immobilization significantly reduced maximum force, energy uptake, stiffness, tendon length, transverse area, stress, organized collagen diameter and collagen III-LI occurrence by respectively 80, 75, 77, 22, 47, 65, 49, and 83% compared to free mobilization. IPC treatment improved maximum force 65%, energy 168%, organized collagen diameter 50%, tendon length 25%, and collagen III-LI occurrence 150% compared to immobilization only. The results confirm that immobilization impairs healing after tendon rupture and furthermore demonstrate that IPC-treatment can enhance proliferative tendon repair by counteracting biomechanical and morphological deficits caused by immobilization.

  14. Engineering Tendon: Scaffolds, Bioreactors, and Models of Regeneration

    PubMed Central

    Youngstrom, Daniel W.; Barrett, Jennifer G.

    2016-01-01

    Tendons bridge muscle and bone, translating forces to the skeleton and increasing the safety and efficiency of locomotion. When tendons fail or degenerate, there are no effective pharmacological interventions. The lack of available options to treat damaged tendons has created a need to better understand and improve the repair process, particularly when suitable autologous donor tissue is unavailable for transplantation. Cells within tendon dynamically react to loading conditions and undergo phenotypic changes in response to mechanobiological stimuli. Tenocytes respond to ultrastructural topography and mechanical deformation via a complex set of behaviors involving force-sensitive membrane receptor activity, changes in cytoskeletal contractility, and transcriptional regulation. Effective ex vivo model systems are needed to emulate the native environment of a tissue and to translate cell-matrix forces with high fidelity. While early bioreactor designs have greatly expanded our knowledge of mechanotransduction, traditional scaffolds do not fully model the topography, composition, and mechanical properties of native tendon. Decellularized tendon is an ideal scaffold for cultivating replacement tissue and modeling tendon regeneration. Decellularized tendon scaffolds (DTS) possess high clinical relevance, faithfully translate forces to the cellular scale, and have bulk material properties that match natural tissue. This review summarizes progress in tendon tissue engineering, with a focus on DTS and bioreactor systems. PMID:26839559

  15. Endoscopic Resection of the Tibialis Anterior Tendon Bursa.

    PubMed

    Lui, Tun Hing

    2016-10-01

    The tibialis anterior tendon bursa is located between the tibialis anterior tendon and the medial cuneiform bone and close to the tendon insertion. Bursitis can occur as a result of excessive local friction, infection, arthritides, or direct trauma. Endoscopic resection of the bursa is indicated in case of symptomatic bursitis that is not responding to conservative treatment or infection is suspected. It is contraindicated if there is skin infection at the portal sites. The purpose of this technical note is to describe a minimally invasive approach of endoscopic resection of the tibialis anterior tendon bursa through anterior tibial tendoscopy.

  16. Reconstruction and restoration of neglected ruptured patellar tendon using semitendinosus and gracilis tendons with preserved distal insertions: two case reports.

    PubMed

    Chen, Bin; Li, Runguang; Zhang, Sheng

    2012-08-01

    Neglected rupture of the patellar tendon is rare but becomes more difficult to repair the longer it is left untreated. The most common rupture sites are the inferior pole of the patella and distal insertion. Proximal retraction of the patella and extensor mechanism adhesions makes the treatment more difficult than acute tendon rupture. We report two patients with neglected patellar tendon rupture treated by reconstruction and restoration using semitendinosus-gracilis (STG) tendons with preserved distal insertions. Preserved distal insertion provided sufficient blood supply to accelerate healing, while combined fixation with tension-reducing wire, offered the initial stability of the closed-loop sutured tendon. Both patients reacquired near normal strength and stability of the patellar tendon and restoration of function after operation and rehabilitation.

  17. Neural compensation within the human triceps surae during prolonged walking.

    PubMed

    Cronin, Neil J; Peltonen, Jussi; Sinkjaer, Thomas; Avela, Janne

    2011-02-01

    During human walking, muscle activation strategies are approximately constant across consecutive steps over a short time, but it is unknown whether they are maintained over a longer duration. Prolonged walking may increase tendinous tissue (TT) compliance, which can influence neural activation, but the neural responses of individual muscles have not been investigated. This study investigated the hypothesis that muscle activity is up- or down-regulated in individual triceps surae muscles during prolonged walking. Thirteen healthy subjects walked on a treadmill for 60 min at 4.5 km/h, while triceps surae muscle activity, maximal muscle compound action potentials, and kinematics were recorded every 5 min, and fascicle lengths were estimated at the beginning and end of the protocol using ultrasound. After 1 h of walking, soleus activity increased by 9.3 ± 0.2% (P < 0.05) and medial gastrocnemius activity decreased by 9.3 ± 0.3% (P < 0.01). Gastrocnemius fascicle length at ground contact shortened by 4.45 ± 0.99% (P < 0.001), whereas soleus fascicle length was unchanged (P = 0.988). Throughout the stance phase, medial gastrocnemius fascicle lengthening decreased by 44 ± 13% (P < 0.001), whereas soleus fascicle lengthening amplitude was unchanged (P = 0.650). The data suggest that a compensatory neural strategy exists between triceps surae muscles and that changes in muscle activation are generally mirrored by changes in muscle fascicle length. These findings also support the notion of muscle-specific changes in TT compliance after prolonged walking and highlight the ability of the CNS to maintain relatively constant movement patterns in spite of neuromechanical changes in individual muscles.

  18. Statins induce biochemical changes in the Achilles tendon after chronic treatment.

    PubMed

    de Oliveira, Letícia Prado; Vieira, Cristiano Pedrozo; Da Ré Guerra, Flávia; de Almeida, Marcos dos Santos; Pimentel, Edson Rosa

    2013-09-15

    Statins have been widely prescribed as lipid-lowering drugs and are associated with tendon rupture. Therefore, this study aimed to evaluate the possible biochemical changes in the Achilles tendon of rats after chronic treatment with statins. Dosages of statins were calculated using allometric scaling with reference to the 80mg/day and 20mg/day, doses recommended for humans. The rats were divided into the following groups: treated with simvastatin (S-20 and S-80), treated with atorvastatin (A-20 and A-80), and the control group that received no treatment (C). Measurements of low-density lipoprotein (LDL) in the plasma were performed. The levels of non-collagenous proteins, glycosaminoglycans (GAGs) and hydroxyproline were quantified. Western blotting for collagen I was performed, and the presence of metalloproteinases (MMPs)-2 and -9 was investigated through zymography. The concentration of non-collagenous proteins in S-20 was less than the C group. There was a significant increase in pro-MMP-2 activity in A-80 group and in active MMP-2 in S-20 group compared to the C group. A significant increase in latent MMP-9 activity was observed in both the A-80 and S-20 groups when compared to C group. In the A-20 group, there was a lower amount of collagen I in relation to C group. In addition, a higher concentration of hydroxyproline was found in the S-20 group than the C group. The analysis of GAGs showed a significant increase in the A-20 group when compared to C group. The treatment induced remarkable alterations in the Achilles tendon and the response of the tissue seems to depend of the used statin dosage. The presence of MMP-2 and MMP-9 is evidence of the degradation and remodeling processes in the extracellular matrix of the tendons. Our results show that statins induce imbalance of extracellular matrix components and possibly induce microdamage in tendons.

  19. MicroRNAs Associated with Shoulder Tendon Matrisome Disorganization in Glenohumeral Arthritis

    PubMed Central

    Thankam, Finosh G.; Boosani, Chandra S.; Dilisio, Matthew F.; Dietz, Nicholas E.

    2016-01-01

    The extracellular matrix (ECM) provides core support which is essential for the cell and tissue architectural development. The role of ECM in many pathological conditions has been well established and ECM-related abnormalities leading to serious consequences have been identified. Though much has been explored in regards to the role of ECM in soft tissue associated pathologies, very little is known about its role in inflammatory disorders in tendon. In this study, we performed microRNA (miRNA) expression analysis in the long head of the human shoulder biceps tendon to identify key genes whose expression was altered during inflammation in patients with glenohumeral arthritis. We identified differential regulation of matrix metalloproteinases (MMPs) that could be critical in collagen type replacement during tendinopathy. The miRNA profiling showed consistent results between the groups and revealed significant changes in the expression of seven different miRNAs in the inflamed tendons. Interestingly, all of these seven miRNAs were previously reported to have either a direct or indirect role in regulating the ECM organization in other pathological disorders. In addition, these miRNAs were also found to alter the expression levels of MMPs, which are the key matrix degrading enzymes associated with ECM-related abnormalities and pathologies. To our knowledge, this is the first report which identifies specific miRNAs associated with inflammation and the matrix reorganization in the tendons. Furthermore, the findings also support the potential role of these miRNAs in altering the collagen type ratio in the tendons during inflammation which is accompanied with differential expression of MMPs. PMID:27992561

  20. Effects of submaximal and maximal long-lasting contractions on the compliance of vastus lateralis tendon and aponeurosis in vivo.

    PubMed

    Ullrich, Anne Charlotte; Mademli, Lida; Arampatzis, Adamantios

    2009-06-01

    The present study investigated the effects of submaximal sustained and maximal repetitive contractions on the compliance of human vastus lateralis (VL) tendon and aponeurosis in vivo using two different fatiguing protocols. Twelve male subjects performed three maximum voluntary isometric contractions (MVC) of the knee extensors before and after two fatiguing protocols on a dynamometer. The first fatiguing protocol consisted of a long-lasting sustained isometric knee extension contraction at 25% MVC until failure (inability to hold the defined load). The second fatiguing protocol included long-lasting isokinetic (90 degrees/s) knee extension contractions, where maximum moment was exerted and failure was proclaimed when this value fell below 70% of unfatigued maximum isokinetic moment. Ultrasonography was used to determine the elongation and strain of the VL tendon and aponeurosis. Muscle fatigue was indicated by a significant decrease in maximum resultant knee extension moment (p<0.05) observed during the MVCs after both long-lasting contractions. No significant (p>0.05) differences in elongation and strain of the VL tendon and aponeurosis were found, when compared every 300 N (tendon force) before and after the fatiguing protocols. The present data indicate, that the VL tendon and aponeurosis in vivo do not suffer from changes in the compliance neither after long-lasting static mechanical loading (strain approximately 3.2%) nor after long-lasting cyclic mechanical loading (strain 6.2-5.5%).

  1. Endoscopic Resection of Gouty Tophus of the Patellar Tendon.

    PubMed

    Lui, Tun Hing

    2015-08-01

    Tophaceous deposition of tendon can result in spontaneous patellar tendon rupture. Surgical therapy may be needed to control symptoms and prevent tendon rupture. Open debridement of the lesion requires a lengthy incision over the lesion; this may result in symptomatic scar adhesion of the patellar tendon or an unhealed wound with persistent tophaceous discharge. Moreover, the other part of the patellar tendon cannot be examined through the incision. We describe a technique for endoscopic resection of a gouty tophus of the patellar tendon. It has the advantage of small incisions away from the lesion and tendon and minimizes wound problems. The whole patellar tendon can be examined endoscopically.

  2. Reconstruction of chronic patellar tendon rupture using graft from contralateral patella graft together with reinforcement from flexor tendons. Case report.

    PubMed

    Frois Temponi, Eduardo; de Carvalho, Lúcio Honório; da Silva Bernardes, Cláudio Otávio; Presses Teixeira, Bruno

    2016-01-01

    Chronic patellar tendon rupture is a rare disabling injury that is technically difficult to repair. The true prevalence of this injury is unknown. Delayed reconstruction of chronic patellar tendon rupture has yielded suboptimal clinical and functional results. Many different surgical methods for reconstruction of chronic patellar tendon injury have been reported. In this report, we present a case with chronic patellar tendon injury that was addressed using a technique that had not previously been described in the literature, through combining procedures that had been described separately. The reconstruction method presented in this article has the advantages of being easy and reproducible, without a requirement of allografts.

  3. Floating patella: combined quadriceps tendon, retinacula, and patellar tendon ruptures in a high-performance elite athlete.

    PubMed

    Langer, Phillip R; Selesnick, F Harlan

    2010-09-01

    Simultaneous quadriceps and patellar tendon rupture is rare. To our knowledge, we present the first known case of simultaneous quadriceps tendon, patella tendon, and retinacula rupture in the ipsilateral knee of a high-performance elite athlete. This disabling injury in the active person results in an inability to actively obtain and maintain full knee extension. When the tendons do not heal properly, at the correct length and tension, knee range of motion and strength can become significantly altered, leading to early fatigue, patellofemoral pain, and possibly instability, preventing return to preinjury status. Immediate surgical repair is recommended for optimal return of knee function and power.

  4. The development of zebrafish tendon and ligament progenitors.

    PubMed

    Chen, Jessica W; Galloway, Jenna L

    2014-05-01

    Despite the importance of tendons and ligaments for transmitting movement and providing stability to the musculoskeletal system, their development is considerably less well understood than that of the tissues they serve to connect. Zebrafish have been widely used to address questions in muscle and skeletal development, yet few studies describe their tendon and ligament tissues. We have analyzed in zebrafish the expression of several genes known to be enriched in mammalian tendons and ligaments, including scleraxis (scx), collagen 1a2 (col1a2) and tenomodulin (tnmd), or in the tendon-like myosepta of the zebrafish (xirp2a). Co-expression studies with muscle and cartilage markers demonstrate the presence of scxa, col1a2 and tnmd at sites between the developing muscle and cartilage, and xirp2a at the myotendinous junctions. We determined that the zebrafish craniofacial tendon and ligament progenitors are neural crest derived, as in mammals. Cranial and fin tendon progenitors can be induced in the absence of differentiated muscle or cartilage, although neighboring muscle and cartilage are required for tendon cell maintenance and organization, respectively. By contrast, myoseptal scxa expression requires muscle for its initiation. Together, these data suggest a conserved role for muscle in tendon development. Based on the similarities in gene expression, morphology, collagen ultrastructural arrangement and developmental regulation with that of mammalian tendons, we conclude that the zebrafish tendon populations are homologous to their force-transmitting counterparts in higher vertebrates. Within this context, the zebrafish model can be used to provide new avenues for studying tendon biology in a vertebrate genetic system.

  5. EGR1 Regulates Transcription Downstream of Mechanical Signals during Tendon Formation and Healing

    PubMed Central

    Delalande, Antony; Bonnin, Marie-Ange; Pichon, Chantal

    2016-01-01

    Background Tendon is a mechanical tissue that transmits forces generated by muscle to bone in order to allow body motion. The molecular pathways that sense mechanical forces during tendon formation, homeostasis and repair are not known. EGR1 is a mechanosensitive transcription factor involved in tendon formation, homeostasis and repair. We hypothesized that EGR1 senses mechanical signals to promote tendon gene expression. Methodology/Principal findings Using in vitro and in vivo models, we show that the expression of Egr1 and tendon genes is downregulated in 3D-engineered tendons made of mesenchymal stem cells when tension is released as well as in tendon homeostasis and healing when mechanical signals are reduced. We further demonstrate that EGR1 overexpression prevents tendon gene downregulation in 3D-engineered tendons when tension is released. Lastly, ultrasound and microbubbles mediated EGR1 overexpression prevents the downregulation of tendon gene expression during tendon healing in reduced load conditions. Conclusion/Significance These results show that Egr1 expression is sensitive to mechanical signals in tendon cells. Moreover, EGR1 overexpression prevents the downregulation of tendon gene expression in the absence of mechanical signals in 3D-engineered tendons and tendon healing. These results show that EGR1 induces a transcriptional response downstream of mechanical signals in tendon cells and open new avenues to use EGR1 to promote tendon healing in reduced load conditions. PMID:27820865

  6. Achilles tendon biomechanics in response to acute intense exercise.

    PubMed

    Joseph, Michael F; Lillie, Kurtis R; Bergeron, Daniel J; Cota, Kevin C; Yoon, Joseph S; Kraemer, William J; Denegar, Craig R

    2014-05-01

    Achilles tendinopathy is a common disorder and is more prevalent in men. Although differences in tendon mechanics between men and women have been reported, understanding of tendon mechanics in young active people is limited. Moreover, there is limited understanding of changes in tendon mechanics in response to acute exercise. Our purpose was to compare Achilles tendon mechanics in active young adult men and women at rest and after light and strenuous activity in the form of repeated jumping with an added load. Participants consisted of 17 men and 14 women (18-30 years) who were classified as being at least moderately physically active as defined by the International Physical Activity Questionnaire. Tendon force/elongation measures were obtained during an isometric plantarflexion contraction on an isokinetic dynamometer with simultaneous ultrasound imaging of the Achilles tendon approximate to the soleus myotendinous junction. Data were collected at rest, after a 10-minute treadmill walk, and after a fatigue protocol of 100 toe jumps performed in a Smith machine, with a load equaling 20% of body mass. We found greater tendon elongation, decreased stiffness, and lower Young's modulus only in women after the jumping exercise. Force and stress were not different between groups but decreased subsequent to the jumping exercise bout. In general, women had greater elongation and strain, less stiffness, and a lower Young's modulus during plantarflexor contraction. These data demonstrate differences in tendon mechanics between men and women and suggest a potential protective mechanism explaining the lower incidence of Achilles tendinopathy in women.

  7. Ultrasonic evaluations of Achilles tendon mechanical properties poststroke

    PubMed Central

    Zhao, Heng; Ren, Yupeng; Wu, Yi-Ning; Liu, Shu Q.; Zhang, Li-Qun

    2009-01-01

    Spasticity, contracture, and muscle weakness are commonly observed poststroke in muscles crossing the ankle. However, it is not clear how biomechanical properties of the Achilles tendon change poststroke, which may affect functions of the impaired muscles directly. Biomechanical properties of the Achilles tendon, including the length and cross-sectional area, in the impaired and unimpaired sides of 10 hemiparetic stroke survivors were evaluated using ultrasonography. Elongation of the Achilles tendon during controlled isometric ramp-and-hold and ramping up then down contractions was determined using a block-matching method. Biomechanical changes in stiffness, Young's modulus, and hysteresis of the Achilles tendon poststroke were investigated by comparing the impaired and unimpaired sides of the 10 patients. The impaired side showed increased tendon length (6%; P = 0.04), decreased stiffness (43%; P < 0.001), decreased Young's modulus (38%; P = 0.005), and increased mechanical hysteresis (1.9 times higher; P < 0.001) compared with the unimpaired side, suggesting Achilles tendon adaptations to muscle spasticity, contracture, and/or disuse poststroke. In vivo quantitative characterizations of the tendon biomechanical properties may help us better understand changes of the calf muscle-tendon unit as a whole and facilitate development of more effective treatments. PMID:19118156

  8. Surgical Strategy for the Chronic Achilles Tendon Rupture

    PubMed Central

    Yang, Liu; Yin, Li

    2016-01-01

    Background. Chronic Achilles tendon rupture is usually misdiagnosed and treated improperly. This study aims to better understand the treatment of chronic Achilles tendon rupture. Methods. Patients who were not able to perform a single-limb heel rise were chosen. Pre- and postoperative magnetic resonance imaging (MRI) were conducted. By evaluating the presence or absence of Achilles tendon stumps and the gap length of rupture, V-Y advancement, gastrocnemius fascial turndown flap, or flexor halluces longus tendon transfer were selected for tendon repair. The function of ankle and foot was assessed by American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot scores and Achilles Tendon Total Rupture Score (ATRS). Results. Twenty-nine patients were followed up. One patient had superficial incision infection, which was healed after debridement and oral antibiotics. Three months postoperatively, MRI showed some signs of inflammation, which disappeared at one or two years postoperatively. All patients were able to perform a single-limb heel rise. Mean AOFAS scores and ATRS scores were increased at the latest follow-up. Conclusion. Surgical options can be determined by evaluating the presence of the Achilles tendon stumps and the gap length, which can avoid using the nearby tendon and yield satisfactory functional results. PMID:27847806

  9. The biceps tendons: From the top and from the bottom

    PubMed Central

    Brasseur, J.L.

    2011-01-01

    The biceps brachii muscle, which inserts proximally onto the scapula and distally onto the forearm, has several tendons with numerous anatomic peculiarities, which render their sonographic examination highly variable. Proximally, the tendon of the short head of the biceps inserts onto the coracoid process and that of the long head on the superior aspect of the glenoid. The distal biceps tendon is bifurcated, and it generally inserts on the radial tuberosity, around which it rolls during pronation/supination. There is a third distal structure, the Lacertus fibrosus, an aponeurosis that branches off from the medial aspect of the tendon, crossing the median artery and median nerve, and inserting on the superficial aponeurosis of the flexor muscles. The sonographic examination of these tendons focuses on nine separate zones of interest: the glenoid insertion of the long head, its extension to the upper pole of the humeral head, the rotator interval, the reflection to the upper bicipital groove, the bicipital groove, the upper myotendinous junction, the lower myotendinous junction, the distal tendon(s), and the inferior enthesis. Because of their morphological and topographical characteristics, the biceps tendons are subject to a variety of lesions, some of which are frequently misdiagnosed on the basis of clinical findings. Ultrasound plays an important role in detecting and characterizing these lesions. Proper examination of the biceps (the distal portion in particular) is a difficult task that cannot be improvised. PMID:23397031

  10. Estimation of Musculotendon Kinematics under Controlled Tendon Indentation

    PubMed Central

    Chardon, Matthieu K.; Dhaher, Yasin Y.; Suresh, Nina I.; Jaramillo, Giselle; Rymer, W. Zev

    2015-01-01

    The effects of tendon indentation on musculotendon unit mechanics have been left largely unexplored. Tendon indentation is however routinely used in the tendon reflex exam to diagnose the state of reflex pathways. Because muscle mechanoreceptors are sensitive to mechanical changes of the musculotendon unit, this gap in knowledge could potentially impact our understanding of these neurological exams. Accordingly, we have used ultrasound (US) imaging to compare the effects of tendon indentation with the effects angular rotation of the elbow in six neurologically intact individuals. We used sagittal ultrasound movies of the biceps brachii to compare length changes induced by each of these perturbations. Length changes were quantified using a pixel-tracking protocol. Our results show that a 20 mm indentation of the distal tendon is broadly equivalent to a 15° elbow rotation. We also show that within the imaging window the strain differences between the two stretching protocols are statistically insignificant. Finally, we show that there exists a significant linear relationship between the two stretching techniques and that this relationship spans a large rotational angle to indentation depth. We have used a novel tendon probe to administer controlled tendon indentations as a way to characterize musculotendon kinematics. Using this probe, we confirm that tendon indentation can be physiologically equated with joint rotation, and can thus be used as an input for muscle stretching protocols. Furthermore, this is potentially a simpler and more practical alternative to externally imposed angular joint motion. PMID:26321363

  11. A biomechanical study of pediatric flexor profundus tendon repair

    PubMed Central

    Al-Thunayan, Turki A.; Al-Zahrani, Mohammed T.; Hakeem, Ahmad A.; Al-Zahrani, Fahad M.; Al-Qattan, Mohammad M.

    2016-01-01

    Objectives: To investigate the tensile strength of repaired flexor profundus tendons in young lambs, which would be equivalent to repairs in children older than 2 years of age. Methods: A comparative in-vitro experimental study conducted at King Saud University, Riyadh, Kingdom of Saudi Arabia from October 2014 to December 2015. We utilized 30 flexor profundus tendons of young lambs with a width of 4 mm. All tendons were repaired with a 4-strand repair technique using 4/0 polypropylene core sutures. In group I (n=10 tendons), 2 separate figure-of-eight sutures were applied. In group II (n=10 tendons), simple locking sutures were added to the corners of 2 separate figure-of-eight sutures. In group III (n=10 tendons), the locked cruciate repair was used. All tendon repairs were tested to single-cycle tensile failure. Results: There was no significant difference between groups II and III with regards to gap and breaking forces; and all forces of these 2 groups were significantly higher than the forces in group I. Conclusion: It was concluded that 4 mm-wide pediatric flexor tendons allow a 4-strand repair and the use of 4/0 sutures. The use of locking sutures increases the tensile strength to values that may allow protective mobilization in children. PMID:27570850

  12. Relationship between tendon stiffness and failure: a metaanalysis.

    PubMed

    LaCroix, Andrew S; Duenwald-Kuehl, Sarah E; Lakes, Roderic S; Vanderby, Ray

    2013-07-01

    Tendon is a highly specialized, hierarchical tissue designed to transfer forces from muscle to bone; complex viscoelastic and anisotropic behaviors have been extensively characterized for specific subsets of tendons. Reported mechanical data consistently show a pseudoelastic, stress-vs.-strain behavior with a linear slope after an initial toe region. Many studies report a linear, elastic modulus, or Young's modulus (hereafter called elastic modulus) and ultimate stress for their tendon specimens. Individually, these studies are unable to provide a broader, interstudy understanding of tendon mechanical behavior. Herein we present a metaanalysis of pooled mechanical data from a representative sample of tendons from different species. These data include healthy tendons and those altered by injury and healing, genetic modification, allograft preparation, mechanical environment, and age. Fifty studies were selected and analyzed. Despite a wide range of mechanical properties between and within species, elastic modulus and ultimate stress are highly correlated (R(2) = 0.785), suggesting that tendon failure is highly strain-dependent. Furthermore, this relationship was observed to be predictable over controlled ranges of elastic moduli, as would be typical of any individual species. With the knowledge gained through this metaanalysis, noninvasive tools could measure elastic modulus in vivo and reasonably predict ultimate stress (or structural compromise) for diseased or injured tendon.

  13. Ultrasonic evaluations of Achilles tendon mechanical properties poststroke.

    PubMed

    Zhao, Heng; Ren, Yupeng; Wu, Yi-Ning; Liu, Shu Q; Zhang, Li-Qun

    2009-03-01

    Spasticity, contracture, and muscle weakness are commonly observed poststroke in muscles crossing the ankle. However, it is not clear how biomechanical properties of the Achilles tendon change poststroke, which may affect functions of the impaired muscles directly. Biomechanical properties of the Achilles tendon, including the length and cross-sectional area, in the impaired and unimpaired sides of 10 hemiparetic stroke survivors were evaluated using ultrasonography. Elongation of the Achilles tendon during controlled isometric ramp-and-hold and ramping up then down contractions was determined using a block-matching method. Biomechanical changes in stiffness, Young's modulus, and hysteresis of the Achilles tendon poststroke were investigated by comparing the impaired and unimpaired sides of the 10 patients. The impaired side showed increased tendon length (6%; P = 0.04), decreased stiffness (43%; P < 0.001), decreased Young's modulus (38%; P = 0.005), and increased mechanical hysteresis (1.9 times higher; P < 0.001) compared with the unimpaired side, suggesting Achilles tendon adaptations to muscle spasticity, contracture, and/or disuse poststroke. In vivo quantitative characterizations of the tendon biomechanical properties may help us better understand changes of the calf muscle-tendon unit as a whole and facilitate development of more effective treatments.

  14. Stem Cell Applications in Tendon Disorders: A Clinical Perspective

    PubMed Central

    Young, Mark

    2012-01-01

    Tendon injuries are a common cause of morbidity and a significant health burden on society. Tendons are structural tissues connecting muscle to bone and are prone to tearing and tendinopathy, an overuse or degenerative condition that is characterized by failed healing and cellular depletion. Current treatments, for tendon tear are conservative, surgical repair or surgical scaffold reconstruction. Tendinopathy is treated by exercises, injection therapies, shock wave treatments or surgical tendon debridement. However, tendons usually heal with fibrosis and scar tissue, which has suboptimal tensile strength and is prone to reinjury, resulting in lifestyle changes with activity restriction. Preclinical studies show that cell therapies have the potential to regenerate rather than repair tendon tissue, a process termed tenogenesis. A number of different cell lines, with varying degrees of differentiation, have being evaluated including stem cells, tendon derived cells and dermal fibroblasts. Even though cellular therapies offer some potential in treating tendon disorders, there have been few published clinical trials to determine the ideal cell source, the number of cells to administer, or the optimal bioscaffold for clinical use. PMID:22448174

  15. Tendon Transfers Around the Foot: When and Where.

    PubMed

    Kuo, Ken N; Wu, Kuan-Wen; Krzak, Joseph J; Smith, Peter A

    2015-12-01

    Tendon transfers are invaluable in the treatment of severe children's foot deformities. They are often preferable to simple releases, lengthening, or fusion in surgical treatment because they provide an active motor function for deformity correction and, when properly selected, the procedures stabilize the foot against progressive deformity. The authors describe 4 commonly used tendon transfer procedures that are useful in children's foot deformity surgeries.

  16. Torque Control of Underactuated Tendon-driven Robotic Fingers

    NASA Technical Reports Server (NTRS)

    Abdallah, Muhammad E. (Inventor); Ihrke, Chris A. (Inventor); Reiland, Matthew J. (Inventor); Wampler, Charles W. (Inventor); Diftler, Myron A. (Inventor); Platt, Robert (Inventor); Bridgwater, Lyndon (Inventor)

    2013-01-01

    A robotic system includes a robot having a total number of degrees of freedom (DOF) equal to at least n, an underactuated tendon-driven finger driven by n tendons and n DOF, the finger having at least two joints, being characterized by an asymmetrical joint radius in one embodiment. A controller is in communication with the robot, and controls actuation of the tendon-driven finger using force control. Operating the finger with force control on the tendons, rather than position control, eliminates the unconstrained slack-space that would have otherwise existed. The controller may utilize the asymmetrical joint radii to independently command joint torques. A method of controlling the finger includes commanding either independent or parameterized joint torques to the controller to actuate the fingers via force control on the tendons.

  17. Bioreactor optimization of tissue engineered rabbit flexor tendons in vivo.

    PubMed

    Thorfinn, J; Angelidis, I K; Gigliello, L; Pham, H M; Lindsey, D; Chang, J

    2012-02-01

    Tissue-engineered rabbit flexor tendons reseeded with cells are stronger in vitro after culture in a bioreactor. It is not known whether this effect persists in vivo. Tenocytes from New Zealand white rabbits were seeded onto rabbit rear paw flexor tendons that were deprived of cells and exposed to cyclic strain in a bioreactor. Reseeded constructs that were kept unloaded in a medium for 5 days were used as controls. The tendons were implanted to bridge a zone II defect in the rabbit. After explantation 4 weeks later, the ultimate tensile strength (UTS) and elastic modulus (EM) were determined. Tendon constructs that were exposed to cyclic strain had significantly improved UTS and EM. Histology showed that cellularity was increased in the bioreactor tendons.

  18. System and Method for Tensioning a Robotically Actuated Tendon

    NASA Technical Reports Server (NTRS)

    Reiland, Matthew J. (Inventor); Diftler, Myron A. (Inventor)

    2013-01-01

    A tendon tensioning system includes a tendon having a proximal end and a distal end, an actuator, and a motor controller. The actuator may include a drive screw and a motor, and may be coupled with the proximal end of the tendon and configured to apply a tension through the tendon in response to an electrical current. The motor controller may be electrically coupled with the actuator, and configured to provide an electrical current having a first amplitude to the actuator until a stall tension is achieved through the tendon; provide a pulse current to the actuator following the achievement of the stall tension, where the amplitude of the pulse current is greater than the first amplitude, and return the motor to a steady state holding current following the conclusion of the pulse current.

  19. Force Model for Control of Tendon Driven Hands

    NASA Technical Reports Server (NTRS)

    Pena, Edward; Thompson, David E.

    1997-01-01

    Knowing the tendon forces generated for a given task such as grasping via a model, an artificial hand can be controlled. A two-dimensional force model for the index finger was developed. This system is assumed to be in static equilibrium, therefore, the equations of equilibrium were applied at each joint. Constraint equations describing the tendon branch connectivity were used. Gaussian elimination was used to solve for the unknowns of the Linear system. Results from initial work on estimating tendon forces in post-operative hands during active motion therapy were discussed. The results are important for understanding the effects of hand position on tendon tension, elastic effects on tendon tension, and overall functional anatomy of the hand.

  20. Specialisation of extracellular matrix for function in tendons and ligaments.

    PubMed

    Birch, Helen L; Thorpe, Chavaunne T; Rumian, Adam P

    2013-01-01

    Tendons and ligaments are similar structures in terms of their composition, organisation and mechanical properties. The distinction between them stems from their anatomical location; tendons form a link between muscle and bone while ligaments link bones to bones. A range of overlapping functions can be assigned to tendon and ligaments and each structure has specific mechanical properties which appear to be suited for particular in vivo function. The extracellular matrix in tendon and ligament varies in accordance with function, providing appropriate mechanical properties. The most useful framework in which to consider extracellular matrix differences therefore is that of function rather than anatomical location. In this review we discuss what is known about the relationship between functional requirements, structural properties from molecular to gross level, cellular gene expression and matrix turnover. The relevance of this information is considered by reviewing clinical aspects of tendon and ligament repair and reconstructive procedures.

  1. Tendon disorders of the hand and wrist.

    PubMed

    McAuliffe, John A

    2010-05-01

    The terminology used to describe most common tendon disorders in the hand and wrist suggests that they are inflammatory in nature, although current evidence indicates that mechanical and degenerative factors are more important. Corticosteroid injections provide relief in 60% or more of cases; however, the duration of their effectiveness remains uncertain. Surgical release of the stenotic pulley or sheath is curative in well over 90% of cases; complications of surgery are rare, and relief is long-lasting. Enlightened management of these common problems demands evidence-based guidelines defining indications for surgery that will maximize outcomes and minimize costs.

  2. Use of X-rays to treat shoulder tendonitis/bursitis: a historical assessment.

    PubMed

    Calabrese, Edward J; Dhawan, Gaurav; Kapoor, Rachna

    2014-08-01

    This article assesses the therapeutic efficacy of ionizing radiation for the treatment of shoulder tendonitis/bursitis in the USA over the period of its use (human 1936-1961; veterinary 1954-1974). Results from ~3,500 human cases were reported in the clinical case studies over 30 articles, and indicated a high treatment efficacy (>90 %) for patients. Radiotherapy was effective with a single treatment. The duration of treatment effectiveness was prolonged, usually lasting until the duration of the follow-up period (i.e., 1-5 years). Therapeutic effectiveness was reduced for conditions characterized as chronic. Similar findings were reported with race horses in the veterinary literature. These historical findings are consistent with clinical studies over the past several decades in Germany, which have used more rigorous study designs and a broader range of clinical evaluation parameters. Radiotherapy treatment was widely used in the mid twentieth century in the USA, but was abandoned following the discovery of anti-inflammatory drugs and the fear of radiation-induced cancer. That X-ray treatment could be an effective means of treating shoulder tendonitis/bursitis, as a treatment option, and is essentially unknown by the current medical community. This paper is the first comprehensive synthesis of the historical use of X-rays to treat shoulder tendonitis/bursitis and its efficacy in the USA.

  3. New anchoring method for tarsal tendon transfers in myelomeningocele patients.

    PubMed

    Tomonori, Kenmoku; Makoto, Kamegaya; Takashi, Saisu

    2007-12-01

    We describe a new anchoring method for tarsal tendon transfers in myelomeningocele patients to protect the sole of the foot from pressure sores and skin necrosis and to loosen the tension of the transferred tendon.Tendon transfer procedures were performed in 51 feet (33 patients) with myelomeningocele. We transferred tibialis anterior tendons to the second or third cuneiform in 19 with equinovarus deformities, and transferred tibialis anterior tendons to the calcaneus through the interosseous membrane in 32 with talipes calcaneus. Clinical results were evaluated with the muscle power of transferred tendons using manual muscle testing 6 months after surgery. The muscle test result was classified as good, fair, and poor.After passing the tendon through the bony hole, a 2.0-mm Kirschner wire was inserted from the sole to the tibia through the ankle joint at neutral. (It extended from the sole through the posterior cortex of the tibia.) The remaining part of the wire was bent and formed into a loop shaped like the Greek letter "zeta" (zeta). The thread was then tied to the loop of the wire as tightly as possible. In this way, there was no contact with the sole during anchoring, thus avoiding ulcers. In addition, the transferred tendon could be kept stable because the patient's ankle was fixed by the Kirschner wire.No cases of wound infection or skin necrosis of the sole occurred. In 49 of the 51 cases, transferred tendons were firmly anchored to tarsal bones. Muscle strength was good for 83%, fair for 13%, and poor for 4%. Consequently, 45 feet could obtain plantigrade pattern during their walking with shoe inserts or occasional use of ankle-foot orthoses.Our anchoring method has the advantage of protecting the sole of the foot from pressure sores and skin necrosis, as well as maintaining tension on the transferred tendon until it settles down in an anchor hole.

  4. Characterization of mechanical and biochemical properties of developing embryonic tendon

    PubMed Central

    Marturano, Joseph E.; Arena, Jeffrey D.; Schiller, Zachary A.; Georgakoudi, Irene; Kuo, Catherine K.

    2013-01-01

    Tendons have uniquely high tensile strength, critical to their function to transfer force from muscle to bone. When injured, their innate healing response results in aberrant matrix organization and functional properties. Efforts to regenerate tendon are challenged by limited understanding of its normal development. Consequently, there are few known markers to assess tendon formation and parameters to design tissue engineering scaffolds. We profiled mechanical and biological properties of embryonic tendon and demonstrated functional properties of developing tendon are not wholly reflected by protein expression and tissue morphology. Using force volume-atomic force microscopy, we found that nano- and microscale tendon elastic moduli increase nonlinearly and become increasingly spatially heterogeneous during embryonic development. When we analyzed potential biochemical contributors to modulus, we found statistically significant but weak correlation between elastic modulus and collagen content, and no correlation with DNA or glycosaminoglycan content, indicating there are additional contributors to mechanical properties. To investigate collagen cross-linking as a potential contributor, we inhibited lysyl oxidase-mediated collagen cross-linking, which significantly reduced tendon elastic modulus without affecting collagen morphology or DNA, glycosaminoglycan, and collagen content. This suggests that lysyl oxidase-mediated cross-linking plays a significant role in the development of embryonic tendon functional properties and demonstrates that changes in cross-links alter mechanical properties without affecting matrix content and organization. Taken together, these data demonstrate the importance of functional markers to assess tendon development and provide a profile of tenogenic mechanical properties that may be implemented in tissue engineering scaffold design to mechanoregulate new tendon regeneration. PMID:23576745

  5. Effect of glenohumeral abduction angle on the mechanical interaction between the supraspinatus and infraspinatus tendons for the intact, partial-thickness torn, and repaired supraspinatus tendon conditions.

    PubMed

    Andarawis-Puri, Nelly; Kuntz, Andrew F; Ramsey, Matthew L; Soslowsky, Louis J

    2010-07-01

    Rotator cuff tears are difficult to manage because of the structural and mechanical inhomogeneity of the supraspinatus tendon. Previously, we showed that with the arm at the side, the supraspinatus and infraspinatus tendons mechanically interact such that conditions that increase supraspinatus tendon strain, such as load or full-thickness tears, also increase infraspinatus tendon strain. This suggests that the infraspinatus tendon may shield the supraspinatus tendon from further injury while becoming at increased risk of injury itself. In this study, the effect of glenohumeral abduction angle on the interaction between the two tendons was evaluated for supraspinatus tendon partial-thickness tears and two repair techniques. Principal strains were quantified in both tendons for 0 degrees , 30 degrees , and 60 degrees of glenohumeral abduction. Results showed that interaction between the two tendons is interrupted by an increase in abduction angle for all supraspinatus tendon conditions evaluated. Infraspinatus tendon strain was lower at 30 degrees and 60 degrees than at 0 degrees abduction angle. In conclusion, interaction between the supraspinatus and infraspinatus tendons is interrupted with increase in abduction angle. Additionally, 30 degrees abduction should be further evaluated for management of rotator cuff tears and repairs as it is the angle at which both supraspinatus and infraspinatus tendon strain is decreased.

  6. Markers for the identification of tendon-derived stem cells in vitro and tendon stem cells in situ - update and future development.

    PubMed

    Lui, Pauline Po Yee

    2015-06-02

    The efficacy of tendon-derived stem cells (TDSCs) for the promotion of tendon and tendon-bone junction repair has been reported in animal studies. Modulation of the tendon stem cell niche in vivo has also been reported to influence tendon structure. There is a need to have specific and reliable markers that can define TDSCs in vitro and tendon stem cells in situ for several reasons: to understand the basic biology of TDSCs and their subpopulations in vitro; to understand the identity, niches and functions of tendon/progenitor stem cells in vivo; to meet the governmental regulatory requirements for quality of TDSCs when translating the exciting preclinical findings into clinical trial/practice; and to develop new treatment strategies for mobilizing endogenous stem/progenitor cells in tendon. TDSCs were reported to express the common mesenchymal stem cell (MSC) markers and some embryonic stem cell (ESC) markers, and there were attempts to use these markers to label tendon stem cells in situ. Are these stem cell markers useful for the identification of TDSCs in vitro and tracking of tendon stem cells in situ? This review aims to discuss the values of the panel of MSC, ESC and tendon-related markers for the identification of TDSCs in vitro. Important factors influencing marker expression by TDSCs are discussed. The usefulness and limitations of the panel of MSC, ESC and tendon-related markers for tracking stem cells in tendon, especially tendon stem cells, in situ are then reviewed. Future research directions are proposed.

  7. Microscopic and histological examination of the mouse hindpaw digit and flexor tendon arrangement with 3D reconstruction

    PubMed Central

    Wong, Jason; Bennett, William; Ferguson, Mark W J; McGrouther, Duncan A

    2006-01-01

    Mice are currently the species of choice for the in vivo study of injury, but few detailed anatomical descriptions have been made of rodent digits, limiting their use for the investigation of intrasynovial tendon healing. In this study a detailed microscopic and histological investigation was performed using C57/BL6 and Tie2 LacZ reporter gene transgenic mice. Serial-sectioned mouse hindpaw digits were characterized using haematoxylin and eosin, Masson's trichrome (collagen), Alcian blue (fibrocartilage), Miller's stain (elastin) and TRITC-phalloidin (cellular cytoskeleton) staining. Digital vasculature was demonstrated using FITC-labelled dextran perfusion studies supplemented with LacZ expression in Tie2 LacZ transgenic mice digits. Imaging of the digit used a combination of brightfield and confocal microscopy with three-dimensional reconstruction. Our findings demonstrated that the mouse hindpaw possesses deep and superficial flexor tendons within a synovial sheath comparable with that found in other mammalian species. The intrasynovial tendons were avascular and had regions of fibrocartilaginous specialization relating to areas of compression. Corresponding vascular networks were demonstrated around the sheath using Tie2 LacZ mice and FITC-perfused hindpaws. Furthermore, there is an area of digit where both deep and superficial tendons reside between two pulleys, similar to zone 2 in the human hand where it would be possible to study intrasynovial tendon injury and adhesion formation. In conclusion, although the dimensions of the mouse digit pose technical challenges for surgical intervention, we have identified a model for the study of flexor tendon injury that will permit future genetic manipulation studies. PMID:17005025

  8. Ruptures of the distal biceps tendon.

    PubMed

    Ward, James P; Shreve, Mark C; Youm, Thomas; Strauss, Eric J

    2014-01-01

    Distal biceps ruptures occur most commonly in middle-aged males and result from eccentric contraction of the biceps tendon. The injury typically presents with pain and a tearing sensation in the antecubital fossa with resultant weakness in flexion and supination strength. Physical exam maneuvers and diagnostic imaging aid in determining the diagnosis. Nonoperative management is reserved for elderly, low demand patients, while operative intervention is generally pursued for younger patients and can consist of nonanatomic repair to the brachialis or anatomic repair to the radial tuberosity. Anatomic repair through a one-incision or two-incision approach is commonplace, while the nonanatomic repairs are rarely performed. No clear advantage exists in operative management with a one-incision versus two-incision techniques. Chronic ruptures present a more difficult situation, and allograft augmentation is often necessary. Common complications after repair include transient nerve palsy, which often resolves, and heterotopic ossification. Despite these possible complications, most studies suggest that better patient outcomes are obtained with operative, anatomic reattachment of the distal biceps tendon.

  9. Changes induced by ozone and ultraviolet light in type I collagen. Bovine Achilles tendon collagen versus rat tail tendon collagen.

    PubMed

    Fujimori, E

    1985-10-15

    High-molecular-mass aggregates were made soluble from insoluble collagens of bovine Achilles tendon and rat tail tendon by limited thermal hydrolysis. These polymeric collagen aggregates were cross-linked by 390-nm-fluorescent 3-hydroxy-pyridinium residues (excited at 325 nm) in the former tendon and by unknown non-fluorescent residues in the latter. With the solubilized insoluble-collagens from both tendons, as well as with acid-soluble collagen from rat tail tendon, other 350-385-nm fluorescence intensities (excited at 300 nm) were found to be higher in monomeric chains than in dimeric and polymeric chains. Low levels of ozone inhibited fibril formation of acid-soluble collagen particularly from young rat tail tendon, reacting with tyrosine residues and the 350-385-nm fluorophores. Aldehyde groups, involved in cross-linking, were not effectively modified by ozone. beta-Components (alpha-chain dimers) were not efficiently dissociated even by higher doses of ozone compared to gamma-components (alpha-chain trimers). Polymeric chain aggregates from bovine Achilles tendon collagen, whose 3-hydroxy-pyridinium cross-links are cleaved by ozone, were more readily dissociated by ozone than those from rat tail tendon collagen. Ultraviolet (300-nm) light, which destroyed the 350-385-nm fluorophores, inhibited fibril formation less effectively than ultraviolet (275-nm) light, which is absorbed by tyrosine residues, and did not dissociate collagen polymers from rat tail tendon. On the other hand, ultraviolet (320-nm) light, absorbed by 3-hydroxy-pyridinium cross-links which were rapidly photolyzed, partially dissociated polymeric collagen aggregates from bovine Achilles tendon after subsequent heating.

  10. Calcium phosphate-hybridized tendon graft to enhance tendon-bone healing two years after ACL reconstruction in goats

    PubMed Central

    2011-01-01

    Background We developed a novel technique to improve tendon-bone attachment by hybridizing calcium phosphate (CaP) with a tendon graft using an alternate soaking process. However, the long-term result with regard to the interface between the tendon graft and the bone is unclear. Methods We analyzed bone tunnel enlargement by computed tomography and histological observation of the interface and the tendon graft with and without the CaP hybridization 2 years after anterior cruciate ligament (ACL) reconstruction in goats using EndoButton and the postscrew technique (CaP, n = 4; control, n = 4). Results The tibial bone tunnel enlargement rates in the CaP group were lower than those in the control group (p < 0.05). In the CaP group, in the femoral and tibial bone tunnels at the anterior and posterior of the joint aperture site, direct insertion-like formation that contained a cartilage layer without tidemarks was more observed at the tendon-bone interface than in the control group (p < 0.05). Moreover, the gap area between the tendon graft and the bone was more observed at the femoral bone tunnel of the joint aperture site in the control group than in the CaP group (p < 0.05). The maturation of the tendon grafts determined using the ligament tissue maturation index was similar in both groups. Conclusions The CaP-hybridized tendon graft enhanced the tendon-bone healing 2 years after ACL reconstruction in goats. The use of CaP-hybridized tendon grafts can reduce the bone tunnel enlargement and gap area associated with the direct insertion-like formation in the interface near the joint. PMID:22166674

  11. Conflicts, snapping and instability of the tendons. Pictorial essay

    PubMed Central

    Fantino, Olivier; Borne, J.; Bordet, Bertrand

    2012-01-01

    Conflicts, snapping and instability of the tendons are common, and ultrasound (US) is the method of choice for evidencing these conditions thanks to the possibility to perform dynamic maneuvers during imaging studies. A conflict can occur between a tendon and a bone structure, other tendons, the retinacula or pulleys. Snapping can occur due to instability caused by rupture of the retinaculum, conflict between a thickened retinaculum and a bone prominence or due to an abnormal position of the tendon. Instability can occur due to insufficient ability of the retinaculum to keep the tendons in the bone groove or its failure to hold the tendons applied to the bone. The technique for evidencing conflicts, snapping and instability of the tendons is very demanding because it requires a thorough knowledge of the US appearance and dynamic maneuvers. However, at the present time US examination completed with dynamic maneuvers is the investigation of choice for evidencing these disorders and providing the clinicians with the necessary information. PMID:23396604

  12. Conflicts, snapping and instability of the tendons. Pictorial essay.

    PubMed

    Fantino, Olivier; Borne, J; Bordet, Bertrand

    2012-02-01

    Conflicts, snapping and instability of the tendons are common, and ultrasound (US) is the method of choice for evidencing these conditions thanks to the possibility to perform dynamic maneuvers during imaging studies. A conflict can occur between a tendon and a bone structure, other tendons, the retinacula or pulleys. Snapping can occur due to instability caused by rupture of the retinaculum, conflict between a thickened retinaculum and a bone prominence or due to an abnormal position of the tendon. Instability can occur due to insufficient ability of the retinaculum to keep the tendons in the bone groove or its failure to hold the tendons applied to the bone.The technique for evidencing conflicts, snapping and instability of the tendons is very demanding because it requires a thorough knowledge of the US appearance and dynamic maneuvers. However, at the present time US examination completed with dynamic maneuvers is the investigation of choice for evidencing these disorders and providing the clinicians with the necessary information.

  13. Elbow tendinopathy and tendon ruptures: epicondylitis, biceps and triceps ruptures.

    PubMed

    Rineer, Craig A; Ruch, David S

    2009-03-01

    Lateral and medial epicondylitis are common causes of elbow pain in the general population, with the lateral variety being more common than the medial by a ratio reportedly ranging from 4:1 to 7:1. Initially thought to be an inflammatory condition, epicondylitis has ultimately been shown to result from tendinous microtearing followed by an incomplete reparative response. Numerous nonoperative and operative treatment options have been employed in the treatment of epicondylitis, without the emergence of a single, consistent, universally accepted treatment protocol. Tendon ruptures about the elbow are much less frequent, but result in more significant disability and loss of function. Distal biceps tendon ruptures typically occur in middle-aged males as a result of an event that causes a sudden, eccentric contraction of the biceps. Triceps tendon ruptures are exceedingly rare but usually have a similar etiology with a forceful eccentric contraction of the triceps that causes avulsion of the tendon from the olecranon. The diagnosis of these injuries is not always readily made. Complete ruptures of the biceps or triceps tendons have traditionally been treated surgically with good results. With regard to biceps ruptures, there continues to be debate about the best surgical approach, as well as the best method of fixation of tendon to bone. This article is not meant to be an exhaustive review of the broad topics of elbow tendinopathy and tendon ruptures, but rather is a review of recently published information on the topics that will assist the clinician in diagnosis and management of these conditions.

  14. Temporal Healing in Rat Achilles Tendon: Ultrasound Correlations

    PubMed Central

    Chamberlain, Connie S.; Duenwald-Kuehl, Sarah E.; Okotie, Gregory; Brounts, Sabrina H.; Baer, Geoffrey S.; Vanderby, Ray

    2012-01-01

    The purpose of this study was to explore whether a new ultrasound-based technique correlates with mechanical and biological metrics that describe the tendon healing. Achilles tendons in 32 rats were unilaterally transected and allowed to heal without repair. At 7, 9, 14, or 29 days post-injury, tendons were collected and examined for healing via ultrasound image analysis, mechanical testing, and immunohistochemistry. Consistent with previous studies, we observe that the healing tendons are mechanically inferior (ultimate stress, ultimate load, and normalized stiffness) and biologically altered (cellular and ECM factors) compared to contralateral controls with an incomplete recovery over healing time. Unique to this study, we report: 1) Echo intensity (defined by gray-scale brightness in the ultrasound image) in the healing tissue is related to stress and normalized stiffness. 2) Elongation to failure is relatively constant so that tissue normalized stiffness is linearly correlated with ultimate stress. Together, 1 and 2 suggest a method to quantify mechanical compromise in healing tendons. 3) The amount and type of collagen in healing tendons associates with their strength and normalized stiffness as well as their ultrasound echo intensity. 4) A significant increase of periostin in the healing tissues suggests an important but unexplored role for this ECM protein in tendon healing. PMID:23149902

  15. Tenocyte contraction induces crimp formation in tendon-like tissue

    PubMed Central

    Holmes, David F.; Hill, Patrick; Kadler, Karl E.; Margetts, Lee

    2013-01-01

    Tendons are composed of longitudinally aligned collagen fibrils arranged in bundles with an undulating pattern, called crimp. The crimp structure is established during embryonic development and plays a vital role in the mechanical behaviour of tendon, acting as a shock absorber during loading. However, the mechanism of crimp formation is unknown, partly because of the difficulties of studying tendon development in vivo. Here we used a 3D cell culture system in which embryonic tendon fibroblasts synthesize a tendon-like construct comprised of collagen fibrils arranged in parallel bundles. Investigations using polarized light microscopy, scanning electron microscopy and fluorescence microscopy showed that tendon-constructs contained a regular pattern of wavy collagen fibrils. Tensile testing indicated that this superstructure was a form of embryonic crimp producing a characteristic toe region in the stress-strain curves. Furthermore, contraction of tendon fibroblasts was the critical factor in the buckling of collagen fibrils during the formation of the crimp structure. Using these biological data, a finite element model was built that mimics the contraction of the tendon fibroblasts and monitors the response of the ECM. The results show that the contraction of the fibroblasts is a sufficient mechanical impulse to build a planar wavy pattern. Furthermore, the value of crimp wavelength was determined by the mechanical properties of the collagen fibrils and inter-fibrillar matrix. Increasing fibril stiffness combined with constant matrix stiffness led to an increase in crimp wavelength. The data suggest a novel mechanism of crimp formation, and the finite element model indicates the minimum requirements to generate a crimp structure in embryonic tendon. PMID:21735243

  16. Mechanical properties of the flexor digitorum profundus tendon attachment.

    PubMed

    Felder, Jerrod J; Guseila, Loredana M; Saranathan, Archana; Shary, Timothy J; Lippitt, Steven B; Elias, John J

    2013-12-01

    The current study was performed to determine the strength and rigidity of the intact flexor digitorum profundus (FDP) tendon attachment and compare the rigidity at the attachment site to the rigidity within a more proximal part of the tendon. Eight cadaveric index fingers were tested to failure of the FDP tendon. Lines were drawn on each tendon with India ink stain at the position of the attachment to bone and 5 mm and 10 mm proximally. Each test was recorded using a high resolution video camera. A minimum of six images per test were used for analysis of tissue deformation. The centroid of each line was computationally identified to characterize the deformation of the tendon between the lines. Force vs. deformation curves were generated for the 5 mm region representing the tendon attachment and the 5 mm region adjacent to the attachment. Stiffness measurements were generated for each curve, and normalized by the initial length to determine the rigidity. The failure strength ranged from 263 N to 548 N, with rigidity values ranging from 2201 N/(mm/mm) to 8714 N/(mm/mm) and from 3459 N/(mm/mm) to 6414 N/(mm/mm) for the attachment and the tendon proximal to the attachment, respectively. The rigidity did not vary significantly between the attachment and proximal tendon based on a Wilcoxon signed rank test (p = 0.2). The measured strength and rigidity establish biomechanical properties for the FDP tendon attachment to bone.

  17. Tenocyte contraction induces crimp formation in tendon-like tissue.

    PubMed

    Herchenhan, Andreas; Kalson, Nicholas S; Holmes, David F; Hill, Patrick; Kadler, Karl E; Margetts, Lee

    2012-03-01

    Tendons are composed of longitudinally aligned collagen fibrils arranged in bundles with an undulating pattern, called crimp. The crimp structure is established during embryonic development and plays a vital role in the mechanical behaviour of tendon, acting as a shock-absorber during loading. However, the mechanism of crimp formation is unknown, partly because of the difficulties of studying tendon development in vivo. Here, we used a 3D cell culture system in which embryonic tendon fibroblasts synthesise a tendon-like construct comprised of collagen fibrils arranged in parallel bundles. Investigations using polarised light microscopy, scanning electron microscopy and fluorescence microscopy showed that tendon constructs contained a regular pattern of wavy collagen fibrils. Tensile testing indicated that this superstructure was a form of embryonic crimp producing a characteristic toe region in the stress-strain curves. Furthermore, contraction of tendon fibroblasts was the critical factor in the buckling of collagen fibrils during the formation of the crimp structure. Using these biological data, a finite element model was built that mimics the contraction of the tendon fibroblasts and monitors the response of the Extracellular matrix. The results show that the contraction of the fibroblasts is a sufficient mechanical impulse to build a planar wavy pattern. Furthermore, the value of crimp wavelength was determined by the mechanical properties of the collagen fibrils and inter-fibrillar matrix. Increasing fibril stiffness combined with constant matrix stiffness led to an increase in crimp wavelength. The data suggest a novel mechanism of crimp formation, and the finite element model indicates the minimum requirements to generate a crimp structure in embryonic tendon.

  18. Multiple tendon xanthomas in patient with heterozygous familial hypercholesterolaemia: sonographic and MRI findings

    PubMed Central

    Dagistan, Emine; Canan, Arzu; Kizildag, Betul; Barut, Abdullah Yuksel

    2013-01-01

    Tendon xanthomas are a component of familial hypercholesterolaemia, which is a hereditary disease and characterised by elevated low-density lipo protein cholesterol plasma levels and premature coronary artery disease. Tendon xanthomas are diagnostic for heterozygous familial hypercholesterolaemia (HFH) and they mostly occur in Achilles tendon. Sonography and MRI are superior to clinical assessment and are useful in detecting tendon xanthomas. In this report, we present ultrasonographic and MRI findings of multiple tendon xanthomas in a case of HFH. PMID:24252837

  19. Development and Application of a Tendon Prosthesis for Early Functional Restoration of the Hand.

    DTIC Science & Technology

    1975-09-01

    blood supply, Hunter tendon, ,tendon synovial fluid tendon prosthesis, tendon pseudo sheath, tendon anastawsis. 20L ASIr RACT (Cw - rev e I nemwee.y am...Healing Process 1. Synovial Fluid Characterizatio : A technique has bee defined that is capable of extracting small micro quantities of fluids from...prosthesis is being studied in the dog and primate with referen ce to gliding pseudo sheath fo=- ation, fluid formation and distal and proximal

  20. Incidence of Major Tendon Ruptures and Anterior Cruciate Ligament Tears in US Army Soldiers

    DTIC Science & Technology

    2007-08-01

    patellar tendon [PT], and Achilles tendon [AT]) has increased in recent decades presumably because of increased recreational sports activity in our...1995 and 1996 were identified and evaluated for risk factors. Results: The authors identified 52 major tendon ruptures: 29 Achilles, 12 patellar , 7... patellar tendon rupture; Achilles tendon rupture; race; mechanism of injury *Address correspondence to LTC Daniel W. White, MD, 1 Jarrett White Road

  1. The long head of the biceps tendon is a suitable cell source for tendon tissue regeneration

    PubMed Central

    Pietschmann, Matthias F.; Gülecyüz, Mehmet F.; Ficklscherer, Andreas; Jansson, Volkmar; Müller, Peter E.

    2014-01-01

    Introduction Tendon tissue engineering (TTE) tries to produce tendinous tissue of high quality to replace dysfunctional tissue. One possible application of TTE might be the replacement of ruptured tissue of the rotator cuff. Autologous tenocytes seem to be most suitable as no differentiation in vitro is necessary. Today it is still uncertain if there is a difference between tendon-derived cells (TDC) of different native tissues. Moreover, the search for suitable scaffolds is another important issue in TTE. Material and methods This study compared TDC of the long head of the biceps tendon (LHB), the anterior cruciate ligament (ACL) and the tendon of the musculus semitendinosus (TMS). The TDC were isolated using the cell migration method. Cell morphology was assessed using light microscopy and gene expression was performed using polymerase chain reaction (PCR). Afterwards, cell seeding efficiency and proliferation were tested on a collagen I scaffold using the WST-1 assay. Results were confirmed using H + E staining. Results The TDC of the LHB showed higher expression levels of collagen type I and decorin (p < 0.01) compared to TDC of other origin. Results showed efficient cell seeding and proliferation within the scaffold. Proliferation within the scaffold was not as high as when cells were cultivated without a scaffold. Conclusions The TDC of the LHB seems to be the most suitable cell source. Further research is necessary to find out if the results can be transferred to an in vivo model. The new collagen I scaffold seems to offer an opportunity to combine good biocompatibility and mechanical strength. PMID:25097592

  2. Iliopsoas tendonitis caused by overhang of a collared femoral prosthesis.

    PubMed

    Brew, Christopher J; Stockley, Ian; Grainger, Andrew J; Stone, Martin H

    2011-04-01

    Pain after total hip arthroplasty can be due to a variety of causes, one of the less common being iliopsoas tendonitis. We report an unusual case of iliopsoas tendonitis caused by overhang of the femoral calcar by a collared femoral prosthesis resulting in impingement on the iliopsoas tendon. An ultrasound-guided corticosteroid and local anesthetic diagnostic injection to the site of impingement confirmed the diagnosis with temporary symptom relief. Revision of the femoral stem to a collarless prosthesis resulted in immediate and complete resolution of symptoms.

  3. Chronic Achilles Tendon Disorders: Tendinopathy and Chronic Rupture.

    PubMed

    Maffulli, Nicola; Via, Alessio Giai; Oliva, Francesco

    2015-10-01

    Tendinopathy of the Achilles tendon involves clinical conditions in and around the tendon and it is the result of a failure of a chronic healing response. Although several conservative therapeutic options have been proposed, few of them are supported by randomized controlled trials. The management is primarily conservative and many patients respond well to conservative measures. If clinical conditions do not improve after 6 months of conservative management, surgery is recommended. The management of chronic ruptures is different from that of acute ruptures. The optimal surgical procedure is still debated. In this article chronic Achilles tendon disorders are debated and evidence-based medicine treatment strategies are discussed.

  4. Primary flexor tendon surgery: the search for a perfect result.

    PubMed

    Elliot, David; Giesen, Thomas

    2013-05-01

    Repair of the divided flexor tendon to achieve normal, or near normal, function is an unsolved problem, with each result still uncertain. The authors believe the way forward in primary flexor tendon surgery clinically is by use of strengthened but simpler sutures, appropriate venting of the pulley system, and maintaining early rehabilitation. However, there needs also be consideration of patient factors and other aspects. Research needs to continue more widely, in both the laboratory and the clinical environment, to find ways of better modifying adhesions after surgical repair of the tendon.

  5. Tendon to bone healing and its implications for surgery

    PubMed Central

    Bunker, Daniel Lee John; Ilie, Victor; Ilie, Vladimir; Nicklin, Sean

    2014-01-01

    Summary Entheses are complex structures which act to reduce stress concentrations between tendon and skeleton tissues. Understanding the development and function of the enthesis organ has implications for surgical repair, particularly in regards to healing and the regulation of tendon to bone engraftment. In this paper we review the development and function of entheses as well as the enthesis organ concept. Next we examine the process of tendon to bone healing and how this can be regulated, before addressing implications for surgical repair and post-operative care. PMID:25489553

  6. Bilateral simultaneous infrapatellar tendon ruptures: a case study.

    PubMed

    Noteboom, J T; Lester, M N

    1994-09-01

    This case study reports on a patient with a diagnosis of bilateral patellar tendon ruptures. Bilateral ruptures of the infrapatellar tendons are rare occurrences; approximately 20 cases have been reported in the medical literature. Much of the medical literature concentrates on surgical repair, immediate postoperative follow-up, and final outcome. There is a void in the literature concerning the rehabilitative process of these patients. The subject of this study is a 26-year-old male former collegiate athlete who suffered simultaneous bilateral patellar tendon ruptures while jumping. A rehabilitation model is provided that may assist others treating patients with similar conditions.

  7. A hybrid method for computing achilles tendon moment arm using ultrasound and motion analysis.

    PubMed

    Manal, Kurt; Cowder, Justin D; Buchanan, Thomas S

    2010-05-01

    In this article, we outline a method for computing Achilles tendon moment arm. The moment arm is computed from data collected using two reliable measurement instruments: ultrasound and video-based motion capture. Ultrasound is used to measure the perpendicular distance from the surface of the skin to the midline of the tendon. Motion capture is used to determine the perpendicular distance from the bottom of the probe to the ankle joint center. The difference between these two measures is the Achilles tendon moment arm. Unlike other methods, which require an angular change in joint position to approximate the moment arm, the hybrid method can be used to compute the moment arm directly at a specific joint angle. As a result, the hybrid method involves fewer error-prone measurements and the moment arm can be computed at the limits of the joint range of motion. The method is easy to implement and uses modalities that are less costly and more accessible than MRI. Preliminary testing using a lamb shank as a surrogate for a human ankle revealed good accuracy (3.3% error). We believe the hybrid method outlined here can be used to measure subject-specific moment arms in vivo and thus will potentially benefit research projects investigating ankle mechanics.

  8. NSAID therapy effects on healing of bone, tendon, and the enthesis.

    PubMed

    Su, Bailey; O'Connor, J Patrick

    2013-09-01

    Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used for the treatment of skeletal injuries. The ability of NSAIDs to reduce pain and inflammation is well-established. However, the effects of NSAID therapy on healing of skeletal injuries is less defined. NSAIDs inhibit cyclooxygenase activity to reduce synthesis of prostaglandins, which are proinflammatory, lipid-signaling molecules. Inhibition of cyclooxygenase activity can impact many physiological processes. The effects of NSAID therapy on healing of bone, tendon, and the tendon-to-bone junction (enthesis) have been studied in animal and cell culture models, but human studies are few. Use of different NSAIDs with different pharmacological properties, differences in dosing regimens, and differences in study models and outcome measures have complicated comparisons between studies. In this review, we summarize the mechanisms by which bone, tendon, and enthesis healing occurs, and describe the effects of NSAID therapy on each of these processes. Determining the impact of NSAID therapy on healing of skeletal tissues will enable clinicians to appropriately manage the patient's condition and improve healing outcomes.

  9. Regeneration and repair of tendon and ligament tissue using collagen fibre biomaterials.

    PubMed

    Kew, S J; Gwynne, J H; Enea, D; Abu-Rub, M; Pandit, A; Zeugolis, D; Brooks, R A; Rushton, N; Best, S M; Cameron, R E

    2011-09-01

    Collagen fibres are ubiquitous macromolecular assemblies in nature, providing the structures that support tensile mechanical loads within the human body. Aligned type I collagen fibres are the primary structural motif for tendon and ligament, and therefore biomaterials based on these structures are considered promising candidates for mediating regeneration of these tissues. However, despite considerable investigation, there remains no collagen-fibre-based biomaterial that has undergone clinical evaluation for this application. Recent research in this area has significantly enhanced our understa