WorldWideScience

Sample records for tendon mechanical properties

  1. Mechanical properties of the human Achilles tendon, in vivo

    DEFF Research Database (Denmark)

    Kongsgaard, M; Nielsen, C H; Hegnsvad, S

    2011-01-01

    Ultrasonography has been widely applied for in vivo measurements of tendon mechanical properties. Assessments of human Achilles tendon mechanical properties have received great interest. Achilles tendon injuries predominantly occur in the tendon region between the Achilles-soleus myotendinous...... Achilles tendon in vivo by the use of ultrasonography and 2) assess the between-day reproducibility of these measurements....

  2. Mechanical properties of the human Achilles tendon, in vivo

    DEFF Research Database (Denmark)

    Kongsgaard, M; Nielsen, C H; Hegnsvad, S

    2011-01-01

    Ultrasonography has been widely applied for in vivo measurements of tendon mechanical properties. Assessments of human Achilles tendon mechanical properties have received great interest. Achilles tendon injuries predominantly occur in the tendon region between the Achilles-soleus myotendinous...... junction and Achilles-calcaneus osteotendinous junction i.e. in the free Achilles tendon. However, there has been no adequate ultrasound based method for quantifying the mechanical properties of the free human Achilles tendon. This study aimed to: 1) examine the mechanical properties of the free human...

  3. Region-specific mechanical properties of the human patella tendon

    DEFF Research Database (Denmark)

    Haraldsson, B T; Aagaard, P; Krogsgaard, M

    2004-01-01

    The present study investigated the mechanical properties of tendon fascicles from the anterior and posterior human patellar tendon. Collagen fascicles from the anterior and posterior human patellar tendon in healthy young men (mean +/- SD, 29.0 +/- 4.6 yr, n = 6) were tested in a mechanical rig. ...

  4. Ultrasound-based testing of tendon mechanical properties

    DEFF Research Database (Denmark)

    Seynnes, O R; Bojsen-Møller, J.; Albracht, K

    2015-01-01

    In the past 20 years, the use of ultrasound-based methods has become a standard approach to measure tendon mechanical properties in vivo. Yet the multitude of methodological approaches adopted by various research groups probably contribute to the large variability of reported values. The technique......, or signal synchronization; and 2) in physiological considerations related to the viscoelastic behavior or length measurements of tendons. Hence, the purpose of the present review is to assess and discuss the physiological and technical aspects connected to in vivo testing of tendon mechanical properties...

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

    DEFF Research Database (Denmark)

    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......)), 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....

  6. The Achilles tendon: fundamental properties and mechanisms governing healing

    Science.gov (United States)

    Freedman, Benjamin R.; Gordon, Joshua A.; Soslowsky, Louis J.

    2014-01-01

    Summary This review highlights recent research on Achilles tendon healing, and comments on the current clinical controversy surrounding the diagnosis and treatment of injury. The processes of Achilles tendon healing, as demonstrated through changes in its structure, composition, and biomechanics, are reviewed. Finally, a review of tendon developmental biology and mechano transductive pathways is completed to recognize recent efforts to augment injured Achilles tendons, and to suggest potential future strategies for therapeutic intervention and functional tissue engineering. Despite an abundance of clinical evidence suggesting that current treatments and rehabilitation strategies for Achilles tendon ruptures are equivocal, significant questions remain to fully elucidate the basic science mechanisms governing Achilles tendon injury, healing, treatment, and rehabilitation. PMID:25332943

  7. The structural and mechanical properties of the Achilles tendon 2 years after surgical repair.

    Science.gov (United States)

    Geremia, Jeam Marcel; Bobbert, Maarten Frank; Casa Nova, Mayra; Ott, Rafael Duvelius; Lemos, Fernando de Aguiar; Lupion, Raquel de Oliveira; Frasson, Viviane Bortoluzzi; Vaz, Marco Aurélio

    2015-06-01

    Acute ruptures of the Achilles tendon affect the tendon's structural and mechanical properties. The long-term effects of surgical repair on these properties remain unclear. To evaluate effects of early mobilization versus traditional immobilization rehabilitation programs 2 years after surgical Achilles tendon repair, by comparing force-elongation and stress-strain relationships of the injured tendon to those of the uninjured tendon. A group of males with previous Achilles tendon rupture (n=18) and a group of healthy male controls (n=9) participated. Achilles tendon rupture group consisted of patients that had received early mobilization (n=9) and patients that had received traditional immobilization with a plaster cast (n=9). Comparisons of tendon structural and mechanical properties were made between Achilles tendon rupture and healthy control groups, and between the uninjured and injured sides of the two rehabilitation groups in Achilles tendon rupture group. Ultrasound was used to determine bilaterally tendon cross-sectional area, tendon resting length, and tendon elongation as a function of torque during maximal voluntary plantar flexion. From these data, Achilles tendon force-elongation and stress-strain relationships were determined. The Achilles tendon rupture group uninjured side was not different from healthy control group. Structural and mechanical parameters of the injured side were not different between the Achilles tendon rupture early mobilization and the immobilization groups. Compared to the uninjured side, the injured side showed a reduction in stress at maximal voluntary force, in Young's modulus and in stiffness. Two years post-surgical repair, the Achilles tendon mechanical properties had not returned to the uninjured contralateral tendon values. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Mechanical Properties of Human Patellar Tendon at the Hierarchical levels of Tendon and Fibril

    DEFF Research Database (Denmark)

    Svensson, Rene Brüggebusch; Hansen, Philip; Hassenkam, Tue

    2012-01-01

    that of tendon supports that fibrillar rather than interfibrillar properties govern sub-failure 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...

  9. Alterations in Leg Extensor Muscle-Tendon Unit Biomechanical Properties With Ageing and Mechanical Loading

    Directory of Open Access Journals (Sweden)

    Christopher McCrum

    2018-02-01

    Full Text Available Tendons transfer forces produced by muscle to the skeletal system and can therefore have a large influence on movement effectiveness and safety. Tendons are mechanosensitive, meaning that they adapt their material, morphological and hence their mechanical properties in response to mechanical loading. Therefore, unloading due to immobilization or inactivity could lead to changes in tendon mechanical properties. Additionally, ageing may influence tendon biomechanical properties directly, as a result of biological changes in the tendon, and indirectly, due to reduced muscle strength and physical activity. This review aimed to examine age-related differences in human leg extensor (triceps surae and quadriceps femoris muscle-tendon unit biomechanical properties. Additionally, this review aimed to assess if, and to what extent mechanical loading interventions could counteract these changes in older adults. There appear to be consistent reductions in human triceps surae and quadriceps femoris muscle strength, accompanied by similar reductions in tendon stiffness and elastic modulus with ageing, whereas the effect on tendon cross sectional area is unclear. Therefore, the observed age-related changes in tendon stiffness are predominantly due to changes in tendon material rather than size with age. However, human tendons appear to retain their mechanosensitivity with age, as intervention studies report alterations in tendon biomechanical properties in older adults of similar magnitudes to younger adults over 12–14 weeks of training. Interventions should implement tendon strains corresponding to high mechanical loads (i.e., 80–90% MVC with repetitive loading for up to 3–4 months to successfully counteract age-related changes in leg extensor muscle-tendon unit biomechanical properties.

  10. Ropivacaine alters the mechanical properties of hamstring tendons: In vitro controlled mechanical testing of tendons from living donors.

    Science.gov (United States)

    Ollivier, M; Sbihi, J; Sbihi, A; Pithioux, M; Parratte, S; Argenson, J-N

    2017-11-01

    Intraarticular or periarticular injection of ropivacaine (RI) is an element of current knee surgery practices. The goal of this study was to determine the effects of RI on the mechanical properties of hamstring tendons. We hypothesized that RI would have a detrimental effect on the mechanical properties of periarticular soft tissues METHODS: A tensile test to failure was performed on 120 hamstring tendon segments harvested during ACL reconstruction surgery in 120 patients. Two sets of tensile tests were done. The first evaluated the effect of RI itself on the mechanical properties of tendons: 30 samples were soaked for 1hour in a 2% RI solution and compared to 30 samples soaked in a saline solution (control group). The second evaluated the effect of RI concentration on the mechanical properties of hamstring tendons: 30 samples were soaked for 1hour in a 2% RI solution and 30 samples were soaked in a 7.5% RI solution. In the first test, 29 samples from each group were analyzed as two samples (one in each group) failed at the grip interface. The specimens exposed to 2% RI had lower ultimate tensile strength (Δ=4.4MPa, P=0.001), strain energy (Δ=13MPa, P=0.001) and Young's modulus (Δ=1.6MPa, P=0.02) than the specimens in the control group. There was no significant difference in the strain at failure between groups (Δ=5%, P=0.3). In the second test, one specimen from the 7.5% RI group failed during the preloading and was excluded. There was no significant difference in terms of the load at failure and ultimate tensile stress (Δ=0.45MPa, P=0.6) and strain energy (Δ=0.49MPa, P=0.49) between the two groups. There were significant differences in terms of elongation at failure (Δ=28%, P=0.0003) and Young's modulus (Δ=2.6MPa, P=0.005), with the specimens exposed to 7.5% RI undergoing greater deformation and having a lower Young's modulus. While local RI injections are widely performed in clinical practice, the results of this in vitro study point to short

  11. Structural and mechanical properties of the human Achilles tendon: Sex and strength effects.

    Science.gov (United States)

    Morrison, Sidney M; Dick, Taylor J M; Wakeling, James M

    2015-09-18

    Tendons are elastic structures that connect muscle to the skeletal system and transmit force relative to the amount of stretch they experience. The mechanical properties of human tendons are difficult to measure non-invasively, so generic values are often assumed in musculoskeletal models to represent all subjects. We aimed to determine the in vivo mechanical properties of the human Achilles tendon by calculating tendon stiffness and resting length in 10 male and 10 female trained cyclists. B-mode ultrasound coupled with motion capture was used to track the tendon lengths for the medial and lateral gastrocnemii concurrently with ankle torque measurements during ramped isometric contractions. Achilles tendon stiffness was calculated as the slope of the linear portion of the force-length curve, and this was extrapolated to zero force to yield the tendon resting length. Average Achilles tendon stiffness was 201.8 ± 5.9 N mm(-1). There was no difference in Achilles tendon stiffness or maximum isometric force between males and females, however tendon stiffness varied between individuals. The resting lengths of the MG and LG tendon were 0.209 ± 0.002 m and 0.222 ± 0.002 m respectively, and regression models determined that shank length was the best predictor of resting tendon length. Our results indicate that Achilles tendon stiffness varies with muscle strength and not sex. The variability in Achilles tendon stiffness between subjects support the need for experimentally measured subject-specific tendon properties as input parameters to improve the accuracy of musculoskeletal models. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. The structural and mechanical properties of the Achilles tendon 2 years after surgical repair

    NARCIS (Netherlands)

    Geremia, J.M.; Bobbert, M.F.; Casa Nova, M.; Ott, R.D.; De Aguiar Lemos, F.; De Oliveira Lupion, R.; Frasson, V.B.

    2015-01-01

    Background Acute ruptures of the Achilles tendon affect the tendon's structural and mechanical properties. The long-term effects of surgical repair on these properties remain unclear. Purpose To evaluate effects of early mobilization versus traditional immobilization rehabilitation programs 2 years

  13. Effects of habitual loading on patellar tendon mechanical and morphological properties in basketball and volleyball players.

    Science.gov (United States)

    Zhang, Z J; Ng, G Y F; Fu, S N

    2015-11-01

    Tendon mechanical properties are linked to sports performance and tendon-related injuries, such as tendinopathy. Whether habitual loading, such as participation in regular jumping activities, would induce adaptation on tendon mechanical properties remains unclear. Forty healthy subjects (10 sedentary, 15 volleyball players, and 15 basketball players) aged between 18 and 35 years were recruited. Supersonic shearwave imaging was used to measure the shear elastic modulus and thickness and cross-sectional area (CSA) of the proximal patellar tendons of both knees at 30° of flexion. Significant group differences in tendon shear elastic modulus were found among the three groups. In the dominant leg, reduction in tendon shear elastic modulus by 18.9 % (p = 0.018) and 48.7 % (p = 0.000) were observed in the basketball and volleyball players, respectively, when compared with sedentary subjects. In the non-dominant leg, reduction in tendon shear elastic modulus were 27.3 % (p = 0.034) and 47.1 % (p = 0.02) in the basketball and volleyball players, respectively. The athlete groups were found to have larger CSA but with similar tendon thickness than sedentary group. The CSA were larger by 24-29 % and by 22-24 % in the basketball players and volleyball players, for the dominant and non-dominant legs, respectively (all p < 0.05). Age and body mass are related to tendon stiffness and CSA, particularly in the sedentary subjects. The proximal patellar tendon can undergo substantial adaptation on tendon mechanical and morphological properties when exposed in jumping sports. Intrinsic factors such as age and body mass could influence tendon properties.

  14. Mechanical properties of the patellar tendon in elite volleyball players with and without patellar tendinopathy.

    Science.gov (United States)

    Helland, Christian; Bojsen-Møller, Jens; Raastad, Truls; Seynnes, Olivier R; Moltubakk, Marie M; Jakobsen, Vidar; Visnes, Håvard; Bahr, Roald

    2013-09-01

    Although differences in mechanical properties between symptomatic and healthy tendons have been observed for the Achilles tendon, the impact of tendinopathy on patellar tendon mechanics is not fully documented. The aim of the present case-control study was to assess the mechanical properties of the tendon and jump performance in elite athletes with and without patellar tendinopathy. We identified 17 male volleyball players with patellar tendinopathy and 18 healthy matched controls from a 5-year prospective cohort study on junior elite volleyball players. Outcome variables included three measures of maximal vertical jump performance and ultrasound-based assessments of patellar tendon cross-sectional area, stiffness and Young's modulus. The proximal cross-sectional area of the patellar tendon was significantly larger in the tendinopathic group (133 ± 11 vs 112 ± 9 mm(2), respectively; p jump height and the squat jump height (3.4 ± 2.2 vs 1.2 ± 1.5 cm, p = 0.005) was significantly higher in the tendinopathic group compared with the control group. Patellar tendinopathy is associated with a decrease in the mechanical and material properties of the tendon in elite athletes subjected to a high volume of jumping activity. However, compared with their healthy counterparts, tendinopathic volleyball players have a better ability to utilise the stretch-shortening cycle when jumping.

  15. Mechanical properties of the triceps surae tendon and aponeurosis in relation to intensity of sport activity.

    Science.gov (United States)

    Arampatzis, Adamantios; Karamanidis, Kiros; Morey-Klapsing, Gaspar; De Monte, Gianpiero; Stafilidis, Savvas

    2007-01-01

    The purpose of the present study was to investigate whether the mechanical properties (i.e. force strain relationship) of the triceps surae tendon and aponeurosis relate to the performed sport activity in an intensity-dependent manner. This was done by comparing sprinters with endurance runners and subjects not active in sports. Sixty-six young male subjects (26+/-5 yr; 183+/-6 cm; 77.6+/-6.7 kg) participated in the study. Ten of these subjects were adults not active in sports, 28 were endurance runners and 28 sprinters. All subjects performed isometric maximal voluntary plantar flexion contractions (MVC) on a dynamometer. The distal aponeuroses of the gastrocnemius medialis (GM) was visualised by ultrasound during the MVC. The results showed that only the sprinters had higher normalised stiffness (relationship between tendon force and tendon strain) of the triceps surae tendon and aponeurosis and maximal calculated tendon forces than the endurance runners and the subjects not active in sports. Furthermore, including the data of all 66 examined participants tendon stiffness correlated significantly (r=0.817, Psport activity but rather remain at control level in a wide range of applied strains and that strain amplitude and/or frequency should exceed a given threshold in order to trigger additional adaptation effects. The results further indicate that subjects with higher muscle strength possibly increase the margin of tolerated mechanical loading of the tendon due to the greater stiffness of their triceps surae tendon and aponeurosis.

  16. Effect of alpine skiing training on tendon mechanical properties in older men and women.

    Science.gov (United States)

    Seynnes, O R; Koesters, A; Gimpl, M; Reifberger, A; Niederseer, D; Niebauer, J; Pirich, C; Müller, E; Narici, M V

    2011-08-01

    Strain is one of the parameters determining tendon adaptation to mechanical stimuli. The aim of this study was to test whether the patellar tendon strain induced during recreational alpine skiing would affect tendon mechanical properties in older individuals. Twenty-two older males and females (67 ± 2 years) were assigned to a 12-week guided skiing programme (IG) and 20 aged-matched volunteers served as controls (CG). Patellar tendon mechanical properties and cross-sectional area (CSA) were measured before and after training, with combined dynamometry and ultrasonography scanning. None of the variables changed significantly in the CG after training. In the IG, tendon stiffness and Young's modulus were increased (respectively, 14% and 12%, Palpine skiing is sufficient to elicit adaptive changes in patellar tendon mechanical and material properties in older subjects. Furthermore, the present sex-specific adaptations are consistent with previous reports of lower collagen metabolic responsiveness in women and may be underpinned by anthropometric and metabolic differences. © 2011 John Wiley & Sons A/S.

  17. The effects of immobilization on the mechanical properties of the patellar tendon in younger and older men

    DEFF Research Database (Denmark)

    Couppé, C; Suetta, C; Kongsgaard, M

    2012-01-01

    It remains unknown if inactivity changes the mechanical properties of the human patellar tendon in younger and older healthy persons. The purpose was to examine the effects of short-term unilateral immobilization on the structural and mechanical properties of the patellar tendon in older men and ...

  18. Mechanical muscle and tendon properties of the plantar flexors are altered even in highly functional children with spastic cerebral palsy.

    Science.gov (United States)

    Kruse, Annika; Schranz, Christian; Svehlik, Martin; Tilp, Markus

    2017-12-01

    Recent ultrasound studies found increased passive muscle stiffness and no difference in tendon stiffness in highly impaired children and young adults with cerebral palsy. However, it is not known if muscle and tendon mechanical properties are already altered in highly functional children with cerebral palsy. Therefore, the purpose of this study was to compare the mechanical and material properties of the plantar flexors in highly functional children with cerebral palsy and typically developing children. Besides strength measurements, ultrasonography was used to assess gastrocnemius medialis and Achilles tendon elongation and stiffness, Achilles tendon stress, strain, and Young's modulus in twelve children with cerebral palsy (GMFCS levels I and II) and twelve typically developing peers during passive dorsiflexion rotations as well as maximum voluntary contractions. Despite no difference in ankle joint stiffness (P>0.05) between groups, passive but not active Achilles tendon stiffness was significantly decreased (-39%) and a tendency of increased passive muscle stiffness was observed even in highly functional children with cerebral palsy. However, material properties of the tendon were not altered. Maximum voluntary contraction showed reduced plantar flexor strength (-48%) in the cerebral palsy group. Even in children with mild spastic cerebral palsy, muscle and tendon mechanical properties are altered. However, it appears that the Achilles tendon stiffness is different only when low forces act on the tendon during passive movements. Although maximum voluntary force is already decreased, forces acting on the Achilles tendon during activity appear to be sufficient to maintain typical material properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Effects of resistance training on tendon mechanical properties and rapid force production in prepubertal children.

    Science.gov (United States)

    Waugh, C M; Korff, T; Fath, F; Blazevich, A J

    2014-08-01

    Children develop lower levels of muscle force, and at slower rates, than adults. Although strength training in children is expected to reduce this differential, a synchronous adaptation in the tendon must be achieved to ensure forces continue to be transmitted to the skeleton with efficiency while minimizing the risk of strain-related tendon injury. We hypothesized that resistance training (RT) would alter tendon mechanical properties in children concomitantly with changes in force production characteristics. Twenty prepubertal children (age 8.9 ± 0.3 yr) were equally divided into control (nontraining) and experimental (training) groups. The training group completed a 10-wk RT intervention consisting of 2-3 sets of 8-15 plantar flexion contractions performed twice weekly on a recumbent calf-raise machine. Achilles tendon properties (cross-sectional area, elongation, stress, strain, stiffness, and Young's modulus), electromechanical delay (EMD; time between the onset of muscle activity and force), rate of force development (RFD; slope of the force-time curve), and rate of electromyographic (EMG) increase (REI; slope of the EMG time curve) were measured before and after RT. Tendon stiffness and Young's modulus increased significantly after RT in the experimental group only (∼29% and ∼25%, respectively); all other tendon properties were not significantly altered, although there were mean decreases in both peak tendon strain and strain at a given force level (14% and 24%, respectively; not significant) which may have implications for tendon injury risk and muscle fiber mechanics. A decrease of ∼13% in EMD was found after RT for the experimental group, which paralleled the increase in tendon stiffness (r = -0.59); however, RFD and REI were unchanged. The present data show that the Achilles tendon adapts to RT in prepubertal children and is paralleled by a change in EMD, although the magnitude of this change did not appear to be sufficient to influence RFD. These

  20. Effects of mechanical properties of muscle and tendon on performance in long distance runners.

    Science.gov (United States)

    Kubo, Keitaro; Tabata, Tomonori; Ikebukuro, Toshihiro; Igarashi, Katsumi; Yata, Hideaki; Tsunoda, Naoya

    2010-10-01

    The purpose of this study was to investigate the mechanical properties of muscle and tendon in long distance runners and their relations to running performance. Fifteen long distance runners (LDR) and 21 untrained subjects (CON) participated in this study. Muscle strength and activation level of knee extensors and plantar flexors were measured. Tendon elongation was determined using ultrasonography, while subjects performed ramp isometric knee extension and plantar flexion up to the voluntary maximum. Relative MVC (to body mass) of LDR was significantly lower than that of CON for knee extensors, but not for plantar flexors. No significant difference in the neural activation levels was found between LDR and CON for both sites. Maximal tendon elongation of LDR was significantly lower than that of CON for knee extensors, but not for plantar flexors. Furthermore, faster running time in a 5,000 m race (best official record of LDR) was associated with lower tendon stiffness for both sites. In conclusion, the tendon of long distance runners is less extensible than those of untrained subjects for knee extensors, but not for plantar flexors. For both sites, however, the lower tendon stiffness may be in favor of the running performance in long distance runners.

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

    DEFF Research Database (Denmark)

    Volper, Brent D; Huynh, Richard T; Arthur, Kathryn A

    2015-01-01

    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.......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...

  2. Mechanical properties of the equine superficial digital flexor tendon relate to specific collagen cross-link levels.

    Science.gov (United States)

    Thorpe, C T; Stark, R J F; Goodship, A E; Birch, H L

    2010-11-01

    Damage to the flexor tendons, particularly the superficial digital flexor tendon (SDFT), is one of the most common musculoskeletal injuries sustained by horses competing in all disciplines. Our previous work has shown that SDFTs from different individuals show a wide variation in mechanical strengths; this is important clinically as it may relate to predisposition to injury. The high mechanical strength of tendon relies on the correct orientation of collagen molecules within fibrils and stabilisation by the formation of chemical cross-links between collagen molecules. It is not known whether the variation in SDFT mechanical properties between individuals relates to differences in collagen cross-link levels. Enzyme-derived, intermolecular cross-linking of tendon collagen correlates with mechanical properties of the SDFT. SDFTs were collected from 38 horses and mechanically tested to failure. Structural and material properties were calculated from the load/deformation plot and cross-sectional area for each tendon. Following mechanical testing, pyrrolic cross-link levels were measured using a spectrophotometric assay for Ehrlich's reactivity and pyridinoline levels were quantified by HPLC. Cross-link levels were correlated with mechanical properties and statistical significance tested using a Pearson's correlation test. Pyrrole cross-link levels showed a significant positive correlation with ultimate stress (P = 0.004), yield stress (P = 0.003) and elastic modulus (P = 0.018) of the tendons, despite being a minor cross-link in these tendons. There was no significant correlation of mechanical properties with either hydroxylysyl- or lysyl-pyridinoline levels. Given the low absolute levels of pyrrole, we suggest that the correlation with high mechanical strength is through an indirect mechanism. Understanding the nature of the relationships between pyrrole cross-links, other matrix characteristics and tendon material properties may allow development of strategies to

  3. Can chronic stretching change the muscle-tendon mechanical properties? A review.

    Science.gov (United States)

    Freitas, S R; Mendes, B; Le Sant, G; Andrade, R J; Nordez, A; Milanovic, Z

    2017-08-12

    It is recognized that stretching is an effective method to chronically increase the joint range of motion. However, the effects of stretching training on the muscle-tendon structural properties remain unclear. This systematic review with meta-analysis aimed to determine whether chronic stretching alter the muscle-tendon structural properties. Published papers regarding longitudinal stretching (static, dynamic and/or PNF) intervention (either randomized or not) in humans of any age and health status, with more than 2 weeks in duration and at least 2 sessions per week, were searched in PubMed, PEDro, ScienceDirect and ResearchGate databases. Structural or mechanical variables from joint (maximal tolerated passive torque or resistance to stretch) or muscle-tendon unit (muscle architecture, stiffness, extensibility, shear modulus, volume, thickness, cross-sectional area, and slack length) were extracted from those papers. A total of 26 studies were selected, with a duration ranging from 3 to 8 weeks, and an average total time under stretching of 1165 seconds per week. Small effects were seen for maximal tolerated passive torque, but trivial effects were seen for joint resistance to stretch, muscle architecture, muscle stiffness, and tendon stiffness. A large heterogeneity was seen for most of the variables. Stretching interventions with 3- to 8-week duration do not seem to change either the muscle or the tendon properties, although it increases the extensibility and tolerance to a greater tensile force. Adaptations to chronic stretching protocols shorter than 8 weeks seem to mostly occur at a sensory level. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Effect of habitual exercise on the structural and mechanical properties of human tendon, in vivo, in men and women.

    Science.gov (United States)

    Westh, E; Kongsgaard, M; Bojsen-Moller, J; Aagaard, P; Hansen, M; Kjaer, M; Magnusson, S P

    2008-02-01

    We examined whether long-term habitual training (a) was associated with differences in structural and mechanical properties in tendon in women and (b) yielded different tendon properties in men and women. Ten male runners, 10 female runners and 10 female non-runners were tested. Tendon cross-sectional area (CSA) and length of the patellar and Achilles tendon were determined with MRI. Ultrasonography-based measurement of tendon elongation and force during isometric contractions provided mechanical properties. Distal patellar and Achilles tendon CSAs were greater than the proximal part in all three groups (Puntrained women (2.60+/-0.13 mm(2)/kg(3/4)), while that in trained men (3.77+/-0.27 mm(2)/kg(3/4)) was greater compared with trained women (Puntrained women, while that in trained men was greater compared with trained women (Prunners (3528+/-773 N/mm) compared with female runners (2069+/-666 N/mm) and non-runners (2477+/-381 N/mm), (P<0.01), but patellar tendon deformation, stress, strain and modulus were similar. These data indirectly suggest that the ability of Achilles and patellar tendons to adapt in response to habitual loading such as running is attenuated in women.

  5. Mechanical properties and collagen cross-linking of the patellar tendon in old and young men

    DEFF Research Database (Denmark)

    Couppé, C; Hansen, P; Kongsgaard, M

    2009-01-01

    in animals but has never been examined in humans in vivo. In this study, we examined the mechanical properties and pyridinoline and pentosidine cross-link and collagen concentrations of the patellar tendon in vivo in old (OM) and young men (YM). Seven OM (67 +/- 3 years, 86 +/- 10 kg) and 10 YM (27 +/- 2...... lower in OM than in YM (0.49 +/- 0.27 vs. 0.73 +/- 0.14 mg/mg dry wt; P P P ... were higher in OM than in YM (73 +/- 13 vs. 11 +/- 2 mmol/mol; P

  6. Asymmetry of Achilles tendon mechanical and morphological properties between both legs.

    Science.gov (United States)

    Bohm, S; Mersmann, F; Marzilger, R; Schroll, A; Arampatzis, A

    2015-02-01

    Although symmetry of Achilles tendon (AT) properties between legs is commonly assumed in research and clinical settings, different loading profiles of both legs in daily life (i.e., foot dominance) may affect the tendon properties in a side-depended manner. Therefore, AT properties were examined with regard to symmetry between legs. Thirty-six male healthy adults (28 ± 4 years), who were physically active but not involved in sports featuring dissimilar leg load participated. Mechanical and morphological AT properties of the non-dominant and dominant leg were measured by means of ultrasound, magnetic resonance imaging and dynamometry. The AT of the dominant leg featured a significant higher Young's modulus and length (P sport-specific side-depended leg loading. The observed asymmetry may be a result of different loading profiles of both legs during daily activities (i.e., foot dominance) and challenges the general assumption of symmetrical AT properties between legs. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

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

    Science.gov (United States)

    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

  8. Effect of simvastatin on rat supraspinatus tendon mechanical and histological properties in a diet-induced hypercholesterolemia model.

    Science.gov (United States)

    Tucker, Jennica J; Soslowsky, Louis J

    2016-11-01

    Hypercholesterolemia is a common condition and is a risk factor for tendon rupture, specifically in the supraspinatus tendon. In the clinic, statins are commonly prescribed to lower cholesterol, but little information is available examining the effect of statin treatment on the musculoskeletal system. Therefore, the objective of this study was to determine the biomechanical and histological effects of statin treatment in a diet-induced hypercholesterolemia model. We hypothesized that hypercholesterolemic rats treated with statins would have improved tendon biomechanical and histological properties compared to hypercholesterolemic rats not receiving daily statin treatment. Thirty adult male Sprague-Dawley rats ate either high-cholesterol (HC) diet (n = 20) or normal chow (CTL, n = 10). After 6 months, a subset of HC rats began daily oral simvastatin dosing (HC+S) at 20 mg/kg. All rats were sacrificed after a total of 9 months (3 months of statin treatment) and evaluated for histology and mechanics. For mechanics, at the insertion region, HC+S group had increased tendon cross-sectional area decreased and modulus. No differences were noted in mechanical properties at the midsubstance. For histology, no differences were noted in the insertion region. In the midsubstance region, HC+S group had more spindle shaped cells. Our results suggest that 3 months of simvastatin treatment in a diet-induced hypercholesterolemia rat model alters some tendon mechanical and histological properties, although a strong conclusion in support of improved parameters cannot be drawn. Therefore, we conclude that simvastatin treatment does not negatively affect tendon properties. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2009-2015, 2016. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  9. New imaging methods for non-invasive assessment of mechanical, structural and biochemical properties of Human Achilles tendon: a mini review

    Directory of Open Access Journals (Sweden)

    Alexandre Fouré

    2016-07-01

    Full Text Available 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.

  10. Effects of replacing soybean meal with chickpea seeds in the diet on mechanical and thermal properties of tendon tissue in broiler chicken.

    Science.gov (United States)

    Muszynski, S; Kwiecien, M; Swietlicki, M; Dobrowolski, P; Tatarczak, J; Gladyszewska, B

    2018-02-01

    The efficiency of the musculoskeletal system of broiler chickens, in particular during locomotion and in ensuring its supportive function, depends directly on the adequate function and mechanical endurance of soft tissues, including tendons. However, little is known whether the properties of musculoskeletal soft tissues can be influenced by changes of dietary protein. We substituted soybean meal with raw chickpea seeds as the primary protein source in the diet and studied the effects it had on the mechanical and thermal properties of drumstick tendons in broiler Ross 308 chickens. In the experiment, 160 chicks were divided into 2 groups, receiving in their diet either soybean meal (n = 80) or chickpea seeds (n = 80). The experiment lasted 42 days. The physical condition of the drumstick tendons was analyzed on the basis of a tensile test and the results of thermal denaturation as measured by a differential scanning calorimetry. The mechanical evaluation of tendon tensile strength of the broilers fed with chickpea seeds demonstrated an increase in the ultimate strain (for over 22%, P tendon until rupture (for over 57%, P tendon collagen cross-linking as transition onset temperature decreased (from 63.8 to 61.8°C, P tendons and showed that thermal analysis can be a useful tool for studying the effect of nutrition on the development and structural changes in tendons of broiler chickens. © 2017 Poultry Science Association Inc.

  11. Structural mechanical properties of radiation-sterilized human Bone-Tendon-Bone grafts preserved by different methods.

    Science.gov (United States)

    Gut, Grzegorz; Marowska, Joanna; Jastrzebska, Anna; Olender, Ewa; Kamiński, Artur

    2016-06-01

    To avoid the risk of infectious disease transmission from donor to recipient, allografts should be terminally sterilized. In the previous paper (Kaminski et al. in Cell Tissue Bank 10:215-219, 2009) we presented the effect of various methods of preservation (deep fresh freezing, glycerolization, lyophilization), followed by irradiation with different doses of electron beam (EB), on material (intrinsic) mechanical properties of human patellar tendons cut out as for anterior cruciate ligament reconstruction, obtained in failure tensile test. As structural mechanical properties are equally important to predict the behaviour of the graft as a whole functional unit, the purpose of the present paper was to show the results for failure load and elongation, obtained in the same experiment. Paired Bone-Tendon-Bone grafts (BTB) were prepared from cadaveric human patella tendons with both patellar and tibial attachments. They were preserved by deep freezing, glycerolization or lyophilization and subsequently EB-irradiated with the doses of 25, 35, 50 or 100 kGy (fresh-frozen grafts) or a single dose of 35 kGy (glycerolized and lyophilized grafts). Each experimental (irradiated) group was provided with control (non-irradiated), donor-matched group. The specimens from all groups were subjected to mechanical failure tensile test with the use of Instron system in order to measure their structural properties (failure load and elongation). All lyophilized grafts were rehydrated before mechanical testing. In our study we did not observe significant deterioration of structural mechanical properties of BTB grafts processed by fresh-freezing and then terminal sterilized with growing doses of EB up to 100 kGy. In contrast, BTB grafts processed by glycerolization or lyophilization and irradiated with 35 kGy showed significant decrease of failure load. Obtained results suggest that deep-frozen irradiated grafts retain their initial mechanical properties to an extent which does not

  12. Fibril morphology and tendon mechanical properties in patellar tendinopathy: effects of heavy slow resistance training

    DEFF Research Database (Denmark)

    Kongsgaard, Mads; Qvortrup, Klaus; Larsen, Jytte Overgaard

    2010-01-01

    BACKGROUND: Patellar tendinopathy is characterized by pathologic abnormalities. Heavy slow resistance training (HSR) is effective in the management of patellar tendinopathy, but the underlying functional mechanisms remain elusive. PURPOSE: To investigate fibril morphology and mechanical propertie...

  13. Anatomic, Vascular, and Mechanical Overview of the Achilles Tendon.

    Science.gov (United States)

    Dayton, Paul

    2017-04-01

    The Achilles tendon is the strongest and thickest tendon in the body and is subjected to unique forces during the activities of living. A variety of pathologic processes have been identified causing clinical symptoms in patients of all ages. A detailed understanding of Achilles anatomy is necessary to understand the pathologic process that are seen in the tendon. As with all medical topics and conditions, our understanding is evolving as new research sheds light on pathologic processes involved with the Achilles tendon. This article reviews the anatomic, histologic, hemodynamic, and mechanical properties of the Achilles tendon and associated muscle structures. Copyright © 2016 Elsevier Inc. All rights reserved.

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

    DEFF Research Database (Denmark)

    Haraldsson, B T; Aagaard, P; Crafoord-Larsen, D

    2009-01-01

    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 m...

  15. Effect of androgenic-anabolic steroids and heavy strength training on patellar tendon morphological and mechanical properties.

    Science.gov (United States)

    Seynnes, Olivier R; Kamandulis, Sigitas; Kairaitis, Ramutis; Helland, Christian; Campbell, Emma-Louise; Brazaitis, Marius; Skurvydas, Albertas; Narici, Marco V

    2013-07-01

    Combined androgenic-anabolic steroids (AAS) and overloading affects tendon collagen metabolism and ultrastructure and is often associated with a higher risk of injury. The aim of this prospective study was to investigate whether such effects would be reflected in the patellar tendon properties of individuals with a history of long-term resistance training and AAS abuse (RTS group), compared with trained (RT) and untrained (CTRL) nonsteroids users. Tendon cross-sectional area (CSA), stiffness, Young's modulus, and toe limit strain were measured in vivo, from synchronized ultrasonography and dynamometry data. The patellar tendon of RT and RTS subjects was much stiffer and larger than in the CTRL group. However, stiffness and modulus were higher in the RTS group (26%, P < 0.05 and 30%, P < 0.01, respectively) than in the RT group. Conversely, tendon CSA was 15% (P < 0.05) larger in the RT group than in RTS, although differences disappeared when this variable was normalized to quadriceps maximal isometric torque. Yet maximal tendon stress was higher in RTS than in RT (15%, P < 0.05), without any statistical difference in maximal strain and toe limit strain between groups. The present lack of difference in toe limit strain does not substantiate the hypothesis of changes in collagen crimp pattern associated with AAS abuse. However, these findings indicate that tendon adaptations from years of heavy resistance training are different in AAS users, suggesting differences in collagen remodeling. Some of these adaptations (e.g., higher stress) could be linked to a higher risk of tendon injury.

  16. Basic mechanisms of tendon fatigue damage

    OpenAIRE

    Neviaser, Andrew; Andarawis-Puri, Nelly; Flatow, Evan

    2012-01-01

    Pathologic processes intrinsic and extrinsic to the tendons have been proposed as the underlying cause of rotator cuff disease, but the precise etiology is not known. Tear formation is, in part, attributable to the accumulation of subrupture tendon fatigue damage. We review the molecular, mechanical, and structural changes induced in tendons subjected to controlled amounts of fatigue loading in an animal model of early tendinopathy. The distinct tendon responses to low and moderate levels of ...

  17. The effect of running, strength, and vibration strength training on the mechanical, morphological, and biochemical properties of the Achilles tendon in rats

    DEFF Research Database (Denmark)

    Legerlotz, Kirsten; Schjerling, Peter; Langberg, Henning

    2007-01-01

    on the mechanical, morphological, and biochemical properties of the Achilles tendon. Sixty-four female Sprague-Dawley rats were divided into five groups: nonactive age-matched control (AMC; n = 20), voluntary wheel running (RT; n = 20), vibration strength-trained (LVST; n = 12), high-vibration strength......-trained (HVST; n = 6), and high strength-trained (HST; n = 6) group. After a 12-wk-long experimental period, the Achilles tendon was tested mechanically and the cross-sectional area, the soleus and gastrocnemius muscle mass, and mRNA concentration of collagen I, collagen III, tissue inhibitor...

  18. Simvastatin and atorvastatin reduce the mechanical properties of tendon constructs in vitro and introduce catabolic changes in the gene expression pattern

    DEFF Research Database (Denmark)

    Eliasson, Pernilla; Svensson, Rene B; Giannopoulos, Antonis

    2017-01-01

    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...... expression pattern and a reduced collagen content indicated a disturbed balance in matrix production of tendon due to statin administration....

  19. Flexor tendon tissue engineering: acellularization of human flexor tendons with preservation of biomechanical properties and biocompatibility.

    Science.gov (United States)

    Pridgen, Brian C; Woon, Colin Y L; Kim, Maxwell; Thorfinn, Johan; Lindsey, Derek; Pham, Hung; Chang, James

    2011-08-01

    Acellular human tendons are a candidate scaffold for tissue engineering flexor tendons of the hand. This study compared acellularization methods and their compatibility with allogeneic human cells. Human flexor tendons were pretreated with 0.1% ethylenediaminetetracetic acid (EDTA) for 4  h followed by 24  h treatments of 1% Triton X-100, 1% tri(n-butyl)phosphate, or 0.1% or 1% sodium dodecyl sulfate (SDS) in 0.1% EDTA. Outcomes were assessed histologically by hematoxylin and eosin and SYTO green fluorescent nucleic acid stains and biochemically by a QIAGEN DNeasy kit, Sircol collagen assay, and 1,9 dimethylmethylene blue glycosaminoglycan assay. Mechanical data were collected using a Materials Testing System to pull to failure tendons acellularized with 0.1% SDS. Acellularized tendons were re-seeded in a suspension of human dermal fibroblasts. Attachment of viable cells to acellularized tendon was assessed biochemically by a cell viability assay and histologically by a live/dead stain. Data are reported as mean±standard deviation. Compared with the DNA content of fresh tendons (551±212  ng DNA/mg tendon), only SDS treatments significantly decreased DNA content (1% SDS [202.8±37.4  ng DNA/mg dry weight tendon]; 0.1% SDS [189±104  ng DNA/mg tendon]). These findings were confirmed by histology. There was no decrease in glycosaminoglycans or collagen following acellularization with SDS. There was no difference in the ultimate tensile stress (55.3±19.2 [fresh] vs. 51.5±6.9 [0.1% SDS] MPa). Re-seeded tendons demonstrated attachment of viable cells to the tendon surface using a viability assay and histology. Human flexor tendons were acellularized with 0.1% SDS in 0.1% EDTA for 24  h with preservation of mechanical properties. Preservation of collagen and glycoaminoglycans and re-seeding with human cells suggest that this scaffold is biocompatible. This will provide a promising scaffold for future human flexor tendon tissue engineering studies to

  20. Tendon Mineralization Is Progressive and Associated with Deterioration of Tendon Biomechanical Properties, and Requires BMP-Smad Signaling in the Mouse Achilles Tendon Injury Model

    Science.gov (United States)

    Zhang, Kairui; Asai, Shuji; Hast, Michael W.; Liu, Min; Usami, Yu; Iwamoto, Masahiro; Soslowsky, Louis J.; Enomoto-Iwamoto, Motomi

    2016-01-01

    Ectopic tendon mineralization can develop following tendon rupture or trauma surgery. The pathogenesis of ectopic tendon mineralization and its clinical impact have not been fully elucidated yet. In this study, we utilized a mouse Achilles tendon injury model to determine whether ectopic tendon mineralization alters the biomechanical properties of the tendon and whether BMP signaling is involved in this condition. A complete transverse incision was made at the midpoint of the right Achilles tendon in 8-week-old CD1 mice and the gap was left open. Ectopic cartilaginous mass formation was found in the injured tendon by 4 weeks post-surgery and ectopic mineralization was detected at 8–10 weeks post-surgery. Ectopic mineralization grew over time and volume of the mineralized materials of 25-weeks samples was about 2.5 fold bigger than that of 10-weeks samples, indicating that injury-induced ectopic tendon mineralization is progressive. In vitro mechanical testing showed that max force, max stress and mid-substance modulus in the 25-weeks samples were significantly lower than the 10-weeks samples. We observed substantial increases in expression of bone morphogenetic protein family genes in injured tendons 1 week post-surgery. Immunohistochemical analysis showed that phosphorylation of both Smad1 and Smad3 were highly increased in injured tendons as early as 1 week post-injury and remained high in ectopic chondrogenic lesions 4 weeks post-injury. Treatment with the BMP receptor kinase inhibitor (LDN193189) significantly inhibited injury-induced tendon mineralization. These findings indicate that injury-induced ectopic tendon mineralization is progressive, involves BMP signaling and associated with deterioration of tendon biomechanical properties. PMID:26825318

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

    Science.gov (United States)

    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 (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.

  2. Tensile properties of a morphologically split supraspinatus tendon.

    Science.gov (United States)

    Matsuhashi, Tomoya; Hooke, Alexander W; Zhao, Kristin D; Goto, Akira; Sperling, John W; Steinmann, Scott P; An, Kai-Nan

    2014-07-01

    The supraspinatus tendon consists morphologically of two sub-regions, anterior and posterior. The anterior sub-region is thick and tubular while the posterior is thin and strap-like. The purpose of this study was to compare the structural and mechanical properties of the anterior and posterior sub-regions of the supraspinatus tendon. The supraspinatus tendons from seven human cadaveric shoulders were morphologically divided into the anterior and posterior sub-regions. Length, width, and thickness were measured. A servo-hydraulic testing machine (MTS Systems Corporation, Minneapolis, MN) was used for tensile testing. The maximal load at failure, modulus of elasticity and ultimate tendon stress were calculated. Repeated measures were used for statistical comparisons. The mean anterior tendon cross-sectional area was 47.3 mm(2) and the posterior was 32.1 mm(2) . Failure occurred most often at the insertion site: anterior (5/7) and posterior (6/7). All parameters of the anterior sub-region were significantly greater than those of the posterior sub-region. The moduli of elasticity at the insertion site were 592.4 MPa in the anterior sub-region and 217.7 MPa in the posterior (P = 0.01). The ultimate failure loads were 779.2 N in the anterior sub-region and 335.6 N in the posterior (P = 0.003). The ultimate stresses were 22.1 MPa in the anterior sub-region and 11.6 MPa in the posterior (P = 0.008). We recognized that the anterior and posterior sub-regions of the SSP tendon have significantly different mechanical properties. In a future study, we need to evaluate how best to repair an SSP tendon considering these region-specific properties. Copyright © 2013 Wiley Periodicals, Inc.

  3. Tendon material properties vary and are interdependent among turkey hindlimb muscles

    Science.gov (United States)

    Matson, Andrew; Konow, Nicolai; Miller, Samuel; Konow, Pernille P.; Roberts, Thomas J.

    2012-01-01

    SUMMARY The material properties of a tendon affect its ability to store and return elastic energy, resist damage, provide mechanical feedback and amplify or attenuate muscle power. While the structural properties of a tendon are known to respond to a variety of stimuli, the extent to which material properties vary among individual muscles remains unclear. We studied the tendons of six different muscles in the hindlimb of Eastern wild turkeys to determine whether there was variation in elastic modulus, ultimate tensile strength and resilience. A hydraulic testing machine was used to measure tendon force during quasi-static lengthening, and a stress–strain curve was constructed. There was substantial variation in tendon material properties among different muscles. Average elastic modulus differed significantly between some tendons, and values for the six different tendons varied nearly twofold, from 829±140 to 1479±106 MPa. Tendons were stretched to failure, and the stress at failure, or ultimate tensile stress, was taken as a lower-limit estimate of tendon strength. Breaking tests for four of the tendons revealed significant variation in ultimate tensile stress, ranging from 66.83±14.34 to 112.37±9.39 MPa. Resilience, or the fraction of energy returned in cyclic length changes was generally high, and one of the four tendons tested was significantly different in resilience from the other tendons (range: 90.65±0.83 to 94.02±0.71%). An analysis of correlation between material properties revealed a positive relationship between ultimate tensile strength and elastic modulus (r2=0.79). Specifically, stiffer tendons were stronger, and we suggest that this correlation results from a constrained value of breaking strain, which did not vary significantly among tendons. This finding suggests an interdependence of material properties that may have a structural basis and may explain some adaptive responses observed in studies of tendon plasticity. PMID:22771746

  4. Influence of aging on the in vivo properties of human patellar tendon

    DEFF Research Database (Denmark)

    Carroll, CC; Dickinson, J M; Haus, J M

    2008-01-01

    Tendons are important for optimal muscle force transfer to bone and play a key role in functional ability. Changes in tendon properties with aging could contribute to declines in physical function commonly associated with aging. We investigated the in vivo mechanical properties of the patellar te...... of the tendon is altered with aging; however, the physiological and functional consequence of this finding requires further study.......Tendons are important for optimal muscle force transfer to bone and play a key role in functional ability. Changes in tendon properties with aging could contribute to declines in physical function commonly associated with aging. We investigated the in vivo mechanical properties of the patellar.......05), respectively, in men compared with women. After normalization of mechanical properties to a common force, no age differences were apparent; however, stress and strain were 26 and 22% higher, respectively, in women compared with men (P

  5. Males have Inferior Achilles Tendon Material Properties Compared to Females in a Rodent Model.

    Science.gov (United States)

    Pardes, A M; Freedman, B R; Fryhofer, G W; Salka, N S; Bhatt, P R; Soslowsky, L J

    2016-10-01

    The Achilles tendon is the most commonly ruptured tendon in the human body. Numerous studies have reported incidence of these injuries to be upwards of five times as common in men than women. Therefore, the objective of this study was to investigate the sex- and hormone-specific differences between Achilles tendon and muscle between female, ovariectomized female (ovarian hormone deficient), and male rats. Uninjured tissues were collected from all groups for mechanical, structural, and histological analysis. Our results showed that while cross-sectional area and failure load were increased in male tendons, female tendons exhibited superior tendon material properties and decreased muscle fiber size. Specifically, linear and dynamic moduli were increased while viscoelastic properties (e.g., hysteresis, percent relaxation) were decreased in female tendons, suggesting greater resistance to deformation under load and more efficient energy transfer, respectively. No differences were identified in tendon organization, cell shape, cellularity, or proteoglycan content. Additionally, no differences in muscle fiber type distribution were observed between groups. In conclusion, inferior tendon mechanical properties and increased muscle fiber size may explain the increased susceptibility for Achilles tendon injury observed clinically in men compared to women.

  6. Combination of biochemical and mechanical cues for tendon tissue engineering.

    Science.gov (United States)

    Testa, Stefano; Costantini, Marco; Fornetti, Ersilia; Bernardini, Sergio; Trombetta, Marcella; Seliktar, Dror; Cannata, Stefano; Rainer, Alberto; Gargioli, Cesare

    2017-11-01

    Tendinopathies negatively affect the life quality of millions of people in occupational and athletic settings, as well as the general population. Tendon healing is a slow process, often with insufficient results to restore complete endurance and functionality of the tissue. Tissue engineering, using tendon progenitors, artificial matrices and bioreactors for mechanical stimulation, could be an important approach for treating rips, fraying and tissue rupture. In our work, C3H10T1/2 murine fibroblast cell line was exposed to a combination of stimuli: a biochemical stimulus provided by Transforming Growth Factor Beta (TGF-β) and Ascorbic Acid (AA); a three-dimensional environment represented by PEGylated-Fibrinogen (PEG-Fibrinogen) biomimetic matrix; and a mechanical induction exploiting a custom bioreactor applying uniaxial stretching. In vitro analyses by immunofluorescence and mechanical testing revealed that the proposed combined approach favours the organization of a three-dimensional tissue-like structure promoting a remarkable arrangement of the cells and the neo-extracellular matrix, reflecting into enhanced mechanical strength. The proposed method represents a novel approach for tendon tissue engineering, demonstrating how the combined effect of biochemical and mechanical stimuli ameliorates biological and mechanical properties of the artificial tissue compared to those obtained with single inducement. © 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  7. Assessment of the mechanical properties of the muscle-tendon unit by supersonic shear wave imaging elastography: a review

    Directory of Open Access Journals (Sweden)

    Kelly Mônica Marinho e Lima

    2018-01-01

    Full Text Available This review aimed to describe the state of the art in muscle-tendon unit (MTU assessment by supersonic shear wave imaging (SSI elastography in states of muscle contraction and stretching, during aging, and in response to injury and therapeutic interventions. A consensus exists that MTU elasticity increases during passive stretching or contraction, and decreases after static stretching, electrostimulation, massage, and dry needling. There is currently no agreement regarding changes in the MTU due to aging and injury. Currently, the application of SSI for the purpose of diagnosis, rehabilitation, and physical training remains limited by a number of issues, including the lack of normative value ranges, the lack of consensus regarding the appropriate terminology, and an inadequate understanding of the main technical limitations of this novel technology.

  8. Converting round tendons to flat tendon constructs: Does the preparation process have an influence on the structural properties?

    Science.gov (United States)

    Domnick, C; Herbort, M; Raschke, M J; Schliemann, B; Siebold, R; Śmigielski, R; Fink, C

    2017-05-01

    The structural properties of hamstring tendon grafts were evaluated in a porcine model, after processing it to a flat shape, to better replace or augment anatomic flat structures (e.g. ACL, MPFL or MCL). In this biomechanical study, porcine flexor tendons were used which have a comparable shape to semitendinosus and gracilis tendons. One part of the tendon was prepared to a flat tendon construct by splitting the tendon longitudinally with a knife to half of the diameter of the tendon. The semi-split tendon was scratched out to a flat shape. The other matched part was tested in its original round shape. The tendons (n = 40) have been fixed in a uniaxial testing machine (Zwick/Roell) by cryo-clamps after preparing the fixed ends by 2-0 polyester sutures (2-0 Ethibond(®) EXCEL, Ethicon, Somerville, NJ). In every specimen, there was a free 60-mm tendon part between both clamps. The tendons have been loaded to failure to evaluate typical biomechanical parameters such as stiffness, yield load and maximum load. No statistically significant differences (n.s.) regarding stiffness, yield load and maximum load between natively round and processed flat tendons could be detected. A prepared flat-shaped tendon does not show any different structural properties compared with an original round tendon. Therefore, a flat tendon seems to be a biomechanical stable graft option for anatomic reconstruction or augmentation of injured natively flat-shaped structures such as MCL, MPFL or ACL.

  9. From mechanical loading to collagen synthesis, structural changes and function in human tendon

    DEFF Research Database (Denmark)

    Kjær, Michael; Langberg, Henning; Heinemeier, Katja

    2009-01-01

    a similar response whether the tendon was stimulated by concentric, isometric or eccentric muscle contraction, suggesting that strain rather that stress/torque determines the collagen-synthesis stimulating response seen with exercise. The adaptation time to chronic loading is longer in tendon tissue...... of TGF-beta, PGE2, IGF-I plus its binding proteins and interleukin-6 takes place after exercise. The increase in IGF-I expression in tendon includes the isoform that has so far been thought only to exist in skeletal muscle (mechano growth factor). The increase in IGF-I and procollagen expression showed...... compared with contractile elements of skeletal muscle or the heart, and only with very prolonged loading are significant changes in gross dimensions of the tendon observed, suggesting that habitual loading is associated with a robust change in the size and mechanical properties of human tendons...

  10. Uphill running improves rat Achilles tendon tissue mechanical properties and alters gene expression without inducing pathological changes

    DEFF Research Database (Denmark)

    Heinemeier, K M; Skovgaard, D; Bayer, M L

    2012-01-01

    Overuse Achilles tendinopathy is a common and challenging problem in sports medicine. Little is known about the etiology of this disorder, and the development of a good animal model for overuse tendinopathy is essential for advancing insight into the disease mechanisms. Our aim was to test...

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

    Science.gov (United States)

    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.

  12. Quantitative US Elastography Can Be Used to Quantify Mechanical and Histologic Tendon Healing in a Rabbit Model of Achilles Tendon Transection.

    Science.gov (United States)

    Yamamoto, Yohei; Yamaguchi, Satoshi; Sasho, Takahisa; Fukawa, Taisuke; Akatsu, Yorikazu; Akagi, Ryuichiro; Yamaguchi, Tadashi; Takahashi, Kenji; Nagashima, Kengo; Takahashi, Kazuhisa

    2017-05-01

    Purpose To determine the time-dependent change in strain ratios (SRs) at the healing site of an Achilles tendon rupture in a rabbit model of tendon transection and to assess the correlation between SRs and the mechanical and histologic properties of the healing tissue. Materials and Methods Experimental methods were approved by the institutional animal care and use committee. The Achilles tendons of 24 New Zealand white rabbits (48 limbs) were surgically transected. The SRs of Achilles tendons were calculated by using compression-based quantitative ultrasonographic elastography measurements obtained 2, 4, 8, and 12 weeks after transection. After in vivo elastography, the left Achilles tendon was harvested for mechanical testing of ultimate load, ultimate stress, elastic modulus, and linear stiffness, and the right tendons were harvested for tissue histologic analysis with the Bonar scale. Time-dependent changes in SRs, mechanical parameters, and Bonar scale scores were evaluated by using repeated-measures analysis of variance. The correlation between SRs and each measured variable was evaluated by using the Spearman rank correlation coefficient. Results Mean SRs and Bonar scale values decreased as a function of time after transection, whereas mechanical parameters increased (P tendon. (©) RSNA, 2017 Online supplemental material is available for this article.

  13. Differences in tendon properties in elite badminton players with or without patellar tendinopathy.

    Science.gov (United States)

    Couppé, C; Kongsgaard, M; Aagaard, P; Vinther, A; Boesen, M; Kjaer, M; Magnusson, S P

    2013-03-01

    The aim of this study was to examine the structural and mechanical properties of the patellar tendon in elite male badminton players with and without patellar tendinopathy. Seven players with unilateral patellar tendinopathy (PT group) on the lead extremity (used for forward lunge) and nine players with no current or previous patellar tendinopathy (CT group) were included. Magnetic resonance imaging was used to assess distal patellar tendon dimensions. Patellar tendon mechanical properties were assessed using simultaneous tendon force and deformation measurements. Distal tendon cross-sectional area (CSA) normalized for body weight (mm(2) /kg(2/3) ) was lower in the PT group compared with the CT group on both the non-lead extremity (6.1 ± 0.3 vs 7.4 ± 0.2, P < 0.05) and the lead extremity (6.5 ± 0.6 vs 8.4 ± 0.3, P < 0.05). Distal tendon stress was higher in the PT group compared with the CT group for both the non-lead extremity (31 ± 1 vs 27 ± 1 MPa, P < 0.05) and the lead extremity (32 ± 3 vs 21 ± 3 MPa, P < 0.01). Conclusively, the PT group had smaller distal patellar tendon CSA on both the injured (lead extremity) and the uninjured side (non-lead extremity) compared with the CT group. Subsequently, the smaller CSA yielded a greater distal patellar tendon stress in the PT group. Therefore, a small tendon CSA may predispose to the development of tendinopathy. © 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

  14. Effects of flunixin meglumine on experimental tendon wound healing: A histopathological and mechanical study in rabbits

    Science.gov (United States)

    Behfar, Mehdi; Hobbenaghi, Rahim; Sarrafzadeh-Rezaei, Farshid

    2013-01-01

    Tendons are frequently targets of injury in sports and work. Whether nonsteroidal anti-inflammatory drugs (NSAIDs) have beneficial effects on tendon healing is still a matter of debate. This study was conducted to evaluate effects of flunixin meglumine (FM) on tendon healing after experimentally induced acute trauma. Twenty eight adult male New Zealand White rabbits were subjected to complete transection of deep digital flexor tendons followed by suture placement. Treatment group received intramuscular injection of FM for three days, and controls received placebo. Subsequently, cast immobilization was continued for two weeks. Animals were sacrificed four weeks after surgery and tissue samples were taken. The histological evaluations revealed improved structural characteristics of neotendon formation including fibrillar linearity, fibrillar continuity and neovascularization in treatment group compared to those of controls (p 0.05). Mechanical evaluation revealed significant increase in load-related material properties including ultimate load, yield load, energy absorption and ultimate stress in treatment group compared to those of control group (p 0.05). The present study showed that intramuscular injection of FM resulted in improved structural and mechanical properties of tendon repairs and it could be an effective treatment for acute tendon injuries like severance and laceration. PMID:25568677

  15. Effects of flunixin meglumine on experimental tendon wound healing: A histopathological and mechanical study in rabbits

    Directory of Open Access Journals (Sweden)

    Mehdi Behfar

    2014-12-01

    Full Text Available Tendons are frequently targets of injury in sports and work. Whether nonsteroidal anti-inflammatory drugs (NSAIDs have beneficial effects on tendon healing is still a matter of debate. This study was conducted to evaluate effects of flunixin meglumine (FM on tendon healing after experimentally induced acute trauma. Twenty eight adult male New Zealand White rabbits were subjected to complete transection of deep digital flexor tendons followed by suture placement. Treatment group received intramuscular injection of FM for three days, and controls received placebo. Subsequently, cast immobilization was continued for two weeks. Animals were sacrificed four weeks after surgery and tissue samples were taken. The histological evaluations revealed improved structural characteristics of neotendon formation including fibrillar linearity, fibrillar continuity and neovascularization in treatment group compared to those of controls (p 0.05. Mechanical evaluation revealed significant increase in load-related material properties including ultimate load, yield load, energy absorption and ultimate stress in treatment group compared to those of control group (p 0.05. The present study showed that intramuscular injection of FM resulted in improved structural and mechanical properties of tendon repairs and it could be an effective treatment for acute tendon injuries like severance and laceration.

  16. Exposure to buffer solution alters tendon hydration and mechanics.

    Science.gov (United States)

    Safa, Babak N; Meadows, Kyle D; Szczesny, Spencer E; Elliott, Dawn M

    2017-08-16

    A buffer solution is often used to maintain tissue hydration during mechanical testing. The most commonly used buffer solution is a physiological concentration of phosphate buffered saline (PBS); however, PBS increases the tissue's water content and decreases its tensile stiffness. In addition, solutes from the buffer can diffuse into the tissue and interact with its structure and mechanics. These bathing solution effects can confound the outcome and interpretation of mechanical tests. Potential bathing solution artifacts, including solute diffusion, and their effect on mechanical properties, are not well understood. The objective of this study was to measure the effects of long-term exposure of rat tail tendon fascicles to several concentrations (0.9-25%) of NaCl, sucrose, polyethylene glycol (PEG), and SPEG (NaCl+PEG) solutions on water content, solute diffusion, and mechanical properties. We found that with an increase in solute concentration the apparent water content decreased for all solution types. Solutes diffused into the tissue for NaCl and sucrose, however, no solute diffusion was observed for PEG or SPEG. The mechanical properties changed for both NaCl solutions, in particular after long-term (8h) incubation the modulus and equilibrium stress decreased compared to short-term (15min) for 25% NaCl, and the cross sectional area increased for 0.9% NaCl. However, the mechanical properties were unchanged for both PEG and SPEG except for minor alterations in stress relaxation parameters. This study shows that NaCl and sucrose buffer solutions are not suitable for long-term mechanical tests. We therefore propose using PEG or SPEG as alternative buffer solutions that after long-term incubation can maintain tissue hydration without solute diffusion and produce a consistent mechanical response. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Immediate effects of whole body vibration on patellar tendon properties and knee extension torque.

    Science.gov (United States)

    Rieder, F; Wiesinger, H-P; Kösters, A; Müller, E; Seynnes, O R

    2016-03-01

    Reports about the immediate effects of whole body vibration (WBV) exposure upon torque production capacity are inconsistent. However, the changes in the torque-angle relationship observed by some authors after WBV may hinder the measurement of torque changes at a given angle. Acute changes in tendon mechanical properties do occur after certain types of exercise but this hypothesis has never been tested after a bout of WBV. The purpose of the present study was to investigate whether tendon compliance is altered immediately after WBV, effectively shifting the optimal angle of peak torque towards longer muscle length. Twenty-eight subjects were randomly assigned to either a WBV (n = 14) or a squatting control group (n = 14). Patellar tendon CSA, stiffness and Young's modulus and knee extension torque-angle relationship were measured using ultrasonography and dynamometry 1 day before and directly after the intervention. Tendon CSA was additionally measured 24 h after the intervention to check for possible delayed onset of swelling. The vibration intervention had no effects on patellar tendon CSA, stiffness and Young's modulus or the torque-angle relationship. Peak torque was produced at ~70° knee angle in both groups at pre- and post-test. Additionally, the knee extension torque globally remained unaffected with the exception of a small (-6%) reduction in isometric torque at a joint angle of 60°. The present results indicate that a single bout of vibration exposure does not substantially alter patellar tendon properties or the torque-angle relationship of knee extensors.

  18. 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.

    Science.gov (United States)

    Li, Shengkun; Ma, Kui; Li, Hong; 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.

  19. Differences in tendon properties in elite badminton players with or without patellar tendinopathy

    DEFF Research Database (Denmark)

    Couppé, C; Kongsgaard, M; Aagaard, P

    2012-01-01

    The aim of this study was to examine the structural and mechanical properties of the patellar tendon in elite male badminton players with and without patellar tendinopathy. Seven players with unilateral patellar tendinopathy (PT group) on the lead extremity (used for forward lunge) and nine players...

  20. Glutaraldehyde cross-linking of tendon mechanical effects at the level of the tendon fascicle and fibril

    DEFF Research Database (Denmark)

    Hansen, Philip; Hassenkam, Tue; Svensson, Rene Bruggebusch

    2009-01-01

    Conclusive insight into the microscopic principles that govern the strength of tendon and related connective tissues is lacking and the importance of collagen cross-linking has not been firmly established. The combined application of whole-tissue mechanical testing and atomic force spectroscopy......-linking on the tensile properties of a single collagen fibril was investigated by a novel methodology based on atomic force spectroscopy. The Young's modulus of a secluded fibril increased from approximately 407 MPa to approximately 1.1 GPa with glutaraldehyde treatment. Collectively, the findings indicate that cross...

  1. The Effect of Phospholipids (Surfactant on Adhesion and Biomechanical Properties of Tendon: A Rat Achilles Tendon Repair Model

    Directory of Open Access Journals (Sweden)

    T. Kursat Dabak

    2015-01-01

    Full Text Available Adhesion of the tendon is a major challenge for the orthopedic surgeon during tendon repair. Manipulation of biological environment is one of the concepts to prevent adhesion. Lots of biochemicals have been studied for this purpose. We aimed to determine the effect of phospholipids on adhesion and biomechanical properties of tendon in an animal tendon repair model. Seventy-two Wistar rats were divided into 4 groups. Achilles tendons of rats were cut and repaired. Phospholipids were applied at two different dosages. Tendon adhesion was determined histopathologically and biomechanical test was performed. At macroscopic evaluation of adhesion, there are statistically significant differences between multiple-dose phospholipid injection group and Control group and also hyaluronic acid group and Control group (p0.008. Ultimate strength was highest at hyaluronic acid injection group and lowest at multiple-dose phospholipid injection group. Single-dose phospholipids (surfactant application may have a beneficial effect on the tendon adhesion. Although multiple applications of phospholipids seem the most effective regime to reduce the tendon adhesion among groups, it deteriorated the biomechanical properties of tendon.

  2. Looped versus single-stranded flexor tendon repairs: a cadaveric mechanical study.

    Science.gov (United States)

    Calfee, Ryan P; Boone, Sean; Stepan, Jeffrey G; Osei, Daniel A; Thomopoulos, Stavros; Boyer, Martin I

    2015-05-01

    To compare the tensile properties of 4-strand modified Kessler flexor tendon repairs using a looped or single-stranded suture. We evaluated the mechanical properties of 4-strand Kessler zone II core suture repairs using either looped or single-stranded suture in human flexor digitorum profundus and flexor pollicis longus tendons. Forty repairs were performed on tendons from bilateral cadaveric hands: 20 matched tendons were divided into equal groups of 3-0 looped and 3-0 single-strand repairs and 20 additional matched tendons were divided into equal groups of 4-0 looped and 4-0 single-strand repairs. Repaired tendons were tested in uniaxial tension to failure to determine mechanical properties and failure modes. Data were analyzed to determine the effect of repair type (ie, looped vs single-stranded) for each suture caliber (ie, 3-0 and 4-0). Single-strand repairs with 3-0 suture demonstrated a significantly greater maximum load to failure and a significantly higher force at 2-mm gap compared with repairs with looped 3-0 suture. All 8 looped repairs with 3-0 suture failed by suture pullout whereas 7 of 8 repairs with 3-0 single-stranded suture failed by suture breakage. The mechanical properties of looped versus single-stranded repairs with 4-0 caliber suture were not statistically different. Repairs with 4-0 caliber suture failed by suture breakage in 8 of 10 single-strand repairs and failed by suture pullout in 6 of 10 repairs with looped suture. In a time-0 ex vivo human cadaveric core suture model, the mechanical properties of a 4-strand repair using 3-0 single-stranded suture were significantly better than the same 4-strand repair performed with looped suture. Four-strand flexor tendon repairs with 3-0 suture are mechanically superior when performed with single-strand suture versus looped suture. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  3. Science to Practice: Quantitative US Elastography Can Be Used to Quantify Mechanical and Histologic Tendon Healing in a Rabbit Model of Achilles Tendon Transection.

    Science.gov (United States)

    Lee, Kenneth S; Martin, Jack; Thelen, Darryl

    2017-05-01

    Compression-based ultrasonographic (US) elastography is associated with time-dependent mechanical and histologic changes of the healing tendon in a transected rabbit model of the Achilles tendon. This finding will lead to continued development of quantitative US, which can be used to objectively assess a diseased or healing tendon. With advances in the method used, clinical translation of tendon elastography may enable clinicians to diagnose tendon damage and track healing, which should improve both treatment and outcome.

  4. Mechanical Analysis of Extra-Articular Knee Ligaments. Part two: Tendon grafts used for knee ligament reconstruction.

    Science.gov (United States)

    Smeets, Kristof; Bellemans, Johan; Scheys, Lennart; Eijnde, Bert O; Slane, Joshua; Claes, Steven

    2017-10-01

    The aim of this study was to provide information about the mechanical properties of grafts used for knee ligament reconstructions and to compare those results with the mechanical properties of native knee ligaments. Eleven cadaveric knees were dissected for the semitendinosus, gracilis, iliotibial band (ITB), quadriceps and patellar tendon. Uniaxial testing to failure was performed using a standardized method and mechanical properties (elastic modulus, ultimate stress, ultimate strain, strain energy density) were determined. The elastic modulus of the gracilis tendon (1458±476MPa) (Pligament reconstructions often differ significantly from the original knee ligament which the graft is supposed to emulate. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Living nanofiber yarn-based woven biotextiles for tendon tissue engineering using cell tri-culture and mechanical stimulation.

    Science.gov (United States)

    Wu, Shaohua; Wang, Ying; Streubel, Philipp N; Duan, Bin

    2017-10-15

    Non-woven nanofibrous scaffolds have been developed for tendon graft application by using electrospinning strategies. However, electrospun nanofibrous scaffolds face some obstacles and limitations, including suboptimal scaffold structure, weak tensile and suture-retention strengths, and compact structure for cell infiltration. In this work, a novel nanofibrous, woven biotextile, fabricated based on electrospun nanofiber yarns, was implemented as a tissue engineered tendon scaffold. Based on our modified electrospinning setup, polycaprolactone (PCL) nanofiber yarns were fabricated with reproducible quality, and were further processed into plain-weaving fabrics interlaced with polylactic acid (PLA) multifilaments. Nonwoven nanofibrous PCL meshes with random or aligned fiber structures were generated using typical electrospinning as comparative counterparts. The woven fabrics contained 3D aligned microstructures with significantly larger pore size and obviously enhanced tensile mechanical properties than their nonwoven counterparts. The biological results revealed that cell proliferation and infiltration, along with the expression of tendon-specific genes by human adipose derived mesenchymal stem cells (HADMSC) and human tenocytes (HT), were significantly enhanced on the woven fabrics compared with those on randomly-oriented or aligned nanofiber meshes. Co-cultures of HADMSC with HT or human umbilical vein endothelial cells (HUVEC) on woven fabrics significantly upregulated the functional expression of most tenogenic markers. HADMSC/HT/HUVEC tri-culture on woven fabrics showed the highest upregulation of most tendon-associated markers than all the other mono- and co-culture groups. Furthermore, we conditioned the tri-cultured constructs with dynamic conditioning and demonstrated that dynamic stretch promoted total collagen secretion and tenogenic differentiation. Our nanofiber yarn-based biotextiles have significant potential to be used as engineered scaffolds to

  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

    Science.gov (United States)

    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. Nonsurgical treatment and early return to activity leads to improved Achilles tendon fatigue mechanics and functional outcomes during early healing in an animal model.

    Science.gov (United States)

    Freedman, Benjamin R; Gordon, Joshua A; Bhatt, Pankti R; Pardes, Adam M; Thomas, Stephen J; Sarver, Joseph J; Riggin, Corinne N; Tucker, Jennica J; Williams, Alexis W; Zanes, Robert C; Hast, Michael W; Farber, Daniel C; Silbernagel, Karin G; Soslowsky, Louis J

    2016-12-01

    Achilles tendon ruptures are common and devastating injuries; however, an optimized treatment and rehabilitation protocol has yet to be defined. Therefore, the objective of this study was to investigate the effects of surgical repair and return to activity on joint function and Achilles tendon properties after 3 weeks of healing. Sprague-Dawley rats (N = 100) received unilateral blunt transection of their Achilles tendon. Animals were then randomized into repaired or non-repaired treatments, and further randomized into groups that returned to activity after 1 week (RTA1) or after 3 weeks (RTA3) of limb casting in plantarflexion. Limb function, passive joint mechanics, and tendon properties (mechanical, organizational using high frequency ultrasound, histological, and compositional) were evaluated. Results showed that both treatment and return to activity collectively affected limb function, passive joint mechanics, and tendon properties. Functionally, RTA1 animals had increased dorsiflexion ROM and weight bearing of the injured limb compared to RTA3 animals 3-weeks post-injury. Such functional improvements in RTA1 tendons were evidenced in their mechanical fatigue properties and increased cross sectional area compared to RTA3 tendons. When RTA1 was coupled with nonsurgical treatment, superior fatigue properties were achieved compared to repaired tendons. No differences in cell shape, cellularity, GAG, collagen type I, or TGF-β staining were identified between groups, but collagen type III was elevated in RTA3 repaired tendons. The larger tissue area and increased fatigue resistance created in RTA1 tendons may prove critical for optimized outcomes in early Achilles tendon healing following complete rupture. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2172-2180, 2016. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  8. How does static stretching influence the tendons mechanical response?

    Science.gov (United States)

    Rossetto, Nathalia Polisello; Fabbro, Inácio Maria Dal; Piedade, Sérgio Rocha

    2013-01-01

    Analyze in vitro the mechanical response of bovine calcaneus tendons subjected to static stretching in three different intervals (15, 30, 45 s). Six groups of bovine calcaneus tendons (n=10) were formed according to the static stretching protocol: three different intervals (15, 30, 45 s) and initial stretching percentage (2.5% and 3.5%). The control group (n=10) did not perform prior stretching. At the end of the stretching tests, the specimens were subjected to stress rupture tests. The values for force relaxation presented stability after the 30(th) second (p<0.0001) at both levels of deformation. Greater force relaxation (p<0.0026) and the least tensile strength (p=0.0123) was observed in the group that was subjected to the highest stretch percentage (3.5%). No difference was observed between the rupture parameters of the stretch and control groups. The variables, stretch duration and percentage did not demonstrate interaction. In relation to force relaxation, the 30 second interval seems to be the most effective when stretching tendons. This fact should be considered when establishing new clinical stretching protocols. Laboratory investigation.

  9. The influence of physical activity during youth on structural and functional properties of the Achilles tendon

    DEFF Research Database (Denmark)

    Lenskjold, A; Kongsgaard, M; Larsen, J O

    2015-01-01

    were either physically active (HAY) or inactive (LAY) in young age. Twelve men in HAY group and eight men in LAY group participated. Structural, functional, and biochemical properties of Achilles tendon were estimated from magnetic resonance imaging, ultrasound video recordings, mechanical tests......-link density did not differ between the groups, nor did collagen fibril density, diameter, and area. There was a correlation between age and pentosidine/collagen within the groups [(HAY: P activity during youth...

  10. Micromechanical properties and collagen composition of ruptured human achilles tendon

    DEFF Research Database (Denmark)

    Hansen, Philip; Kovanen, Vuokko; Hölmich, Per

    2013-01-01

    The Achilles tendon is one of the strongest tendons in the human body, and yet it frequently ruptures, which is a substantial clinical problem. However, the cause of ruptures remains elusive.......The Achilles tendon is one of the strongest tendons in the human body, and yet it frequently ruptures, which is a substantial clinical problem. However, the cause of ruptures remains elusive....

  11. 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

    Directory of Open Access Journals (Sweden)

    Shengkun Li

    2016-01-01

    Full Text Available 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.

  12. Achilles tendon elastic properties remain decreased in long term after rupture.

    Science.gov (United States)

    Frankewycz, B; Penz, A; Weber, J; da Silva, N P; Freimoser, F; Bell, R; Nerlich, M; Jung, E M; Docheva, D; Pfeifer, C G

    2017-11-16

    Rupture of the Achilles tendon results in inferior scar tissue formation. Elastography allows a feasible in vivo investigation of biomechanical properties of the Achilles tendon. The purpose of this study is to investigate the biomechanical properties of healed Achilles tendons in the long term. Patients who suffered from Achilles tendon rupture were recruited for an elastographic evaluation. Unilateral Achilles tendon ruptures were included and scanned in the mid-substance and calcaneal insertion at least 2 years after rupture using shear wave elastography. Results were compared to patients' contralateral non-injured Achilles tendons and additionally to a healthy population. Descriptive statistics, reliability analysis, and correlation analysis with clinical scores were performed. Forty-one patients were included in the study with a mean follow-up-time of 74 ± 30; [26-138] months after rupture. Significant differences were identified in shear wave elastography in the mid-substance of healed tendons (shear wave velocity 1.2 ±1.5 m/s) compared to both control groups [2.5 ±1.5 m/s (p Achilles tendon after rupture has inferior elastic properties even after a long-term healing phase. Differences in elastic properties after rupture mainly originate from the mid-substance of the Achilles tendon, in which most of the ruptures occur. Elastographic results do not correspond with subjective perception. Clinically, sonoelastographical measurements of biomechanical properties can be useful to provide objective insights in tendon recovery.

  13. Medial gastrocnemius muscle fascicle active torque-length and Achilles tendon properties in young adults with spastic cerebral palsy.

    Science.gov (United States)

    Barber, Lee; Barrett, Rod; Lichtwark, Glen

    2012-10-11

    Individuals with spastic cerebral palsy (CP) typically experience muscle weakness. The mechanisms responsible for muscle weakness in spastic CP are complex and may be influenced by the intrinsic mechanical properties of the muscle and tendon. The purpose of this study was to investigate the medial gastrocnemius (MG) muscle fascicle active torque-length and Achilles tendon properties in young adults with spastic CP. Nine relatively high functioning young adults with spastic CP (GMFCS I, 17±2 years) and 10 typically developing individuals (18±2 years) participated in the study. Active MG torque-length and Achilles tendon properties were assessed under controlled conditions on a dynamometer. EMG was recorded from leg muscles and ultrasound was used to measure MG fascicle length and Achilles tendon length during maximal isometric contractions at five ankle angles throughout the available range of motion and during passive rotations imposed by the dynamometer. Compared to the typically developing group, the spastic CP group had 33% lower active ankle plantarflexion torque across the available range of ankle joint motion, partially explained by 37% smaller MG muscle and 4% greater antagonistic co-contraction. The Achilles tendon slack length was also 10% longer in the spastic CP group. This study confirms young adults with mild spastic CP have altered muscle-tendon mechanical properties. The adaptation of a longer Achilles tendon may facilitate a greater storage and recovery of elastic energy and partially compensate for decreased force and work production by the small muscles of the triceps surae during activities such as locomotion. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. What is the impact of inflammation on the critical interplay between mechanical signaling and biochemical changes in tendon matrix?

    DEFF Research Database (Denmark)

    Kjaer, Michael; Bayer, Monika L; Eliasson, Pernilla

    2013-01-01

    Mechanical loading can influence tendon collagen homeostasis in animal models, while the dynamics of the human adult tendon core tissue are more debatable. Currently available data indicate that human tendon adaptation to loading may happen primarily in the outer tendon region. A role of inflamma......Mechanical loading can influence tendon collagen homeostasis in animal models, while the dynamics of the human adult tendon core tissue are more debatable. Currently available data indicate that human tendon adaptation to loading may happen primarily in the outer tendon region. A role...... of inflammation in this peritendinous adaptation is supported by a rise in inflammatory mediators in the peritendinous area after physiological mechanical loading in humans. This plays a role in the exercise-induced rise in tendon blood flow and peritendinous collagen synthesis. Although inflammatory activity can...... at rest nor after acute exercise display any enhanced inflammatory activity, and thus the basis for using anti-inflammatory medication to treat tendon overuse seems limited....

  15. Effect of estrogen on tendon collagen synthesis, tendon structural characteristics, and biomechanical properties in postmenopausal women

    DEFF Research Database (Denmark)

    Hansen, M.; Kongsgaard, M; Holm, Lars

    2009-01-01

    therapy (ERT, n = 10) were studied at rest and in response to one-legged resistance exercise. Synthesis of tendon collagen was determined by stable isotope incorporation [fractional synthesis rate (FSR)] and microdialysis technique (NH(2)-terminal propeptide of type I collagen synthesis). Tendon area...

  16. Functionally Distinct Tendons From Elastin Haploinsufficient Mice Exhibit Mild Stiffening and Tendon-Specific Structural Alteration.

    Science.gov (United States)

    Eekhoff, Jeremy D; Fang, Fei; Kahan, Lindsey G; Espinosa, Gabriela; Cocciolone, Austin J; Wagenseil, Jessica E; Mecham, Robert P; Lake, Spencer P

    2017-11-01

    Elastic fibers are present in low quantities in tendon, where they are located both within fascicles near tenocytes and more broadly in the interfascicular matrix (IFM). While elastic fibers have long been known to be significant in the mechanics of elastin-rich tissue (i.e., vasculature, skin, lungs), recent studies have suggested a mechanical role for elastic fibers in tendons that is dependent on specific tendon function. However, the exact contribution of elastin to properties of different types of tendons (e.g., positional, energy-storing) remains unknown. Therefore, this study purposed to evaluate the role of elastin in the mechanical properties and collagen alignment of functionally distinct supraspinatus tendons (SSTs) and Achilles tendons (ATs) from elastin haploinsufficient (HET) and wild type (WT) mice. Despite the significant decrease in elastin in HET tendons, a slight increase in linear stiffness of both tendons was the only significant mechanical effect of elastin haploinsufficiency. Additionally, there were significant changes in collagen nanostructure and subtle alteration to collagen alignment in the AT but not the SST. Hence, elastin may play only a minor role in tendon mechanical properties. Alternatively, larger changes to tendon mechanics may have been mitigated by developmental compensation of HET tendons and/or the role of elastic fibers may be less prominent in smaller mouse tendons compared to the larger bovine and human tendons evaluated in previous studies. Further research will be necessary to fully elucidate the influence of various elastic fiber components on structure-function relationships in functionally distinct tendons.

  17. Collagen V-heterozygous and -null supraspinatus tendons exhibit altered dynamic mechanical behaviour at multiple hierarchical scales.

    Science.gov (United States)

    Connizzo, Brianne K; Han, Lin; Birk, David E; Soslowsky, Louis J

    2016-02-06

    Tendons function using a unique set of mechanical properties governed by the extracellular matrix and its ability to respond to varied multi-axial loads. Reduction of collagen V expression, such as in classic Ehlers-Danlos syndrome, results in altered fibril morphology and altered macroscale mechanical function in both clinical and animal studies, yet the mechanism by which changes at the fibril level lead to macroscale functional changes has not yet been investigated. This study addresses this by defining the multiscale mechanical response of wild-type, collagen V-heterozygous and -null supraspinatus tendons. Tendons were subjected to mechanical testing and analysed for macroscale properties, as well as microscale (fibre re-alignment) and nanoscale (fibril deformation and sliding) responses. In many macroscale parameters, results showed a dose-dependent response with severely decreased properties in the null group. In addition, both heterozygous and null groups responded to load faster than in wild-type tendons via earlier fibre re-alignment and fibril stretch. However, the heterozygous group exhibited increased fibril sliding, while the null group exhibited no fibril sliding. These studies demonstrate that dynamic responses play an important role in determining overall function and that collagen V is a critical regulator in the development of these relationships.

  18. Acute effects of constant torque and constant angle stretching on the muscle and tendon tissue properties.

    Science.gov (United States)

    Konrad, Andreas; Budini, Francesco; Tilp, Markus

    2017-08-01

    Static stretching induces acute structural changes of the muscle-tendon unit (MTU) that are related to the intensity or duration of stretching. It has been reported that stretching with a constant torque (CT) leads to greater joint range of motion changes than stretching with a constant angle (CA). Whether or not this difference is due to different structural changes of the MTUs of the lower leg and ankle plantar flexors is not known. Therefore, the purpose of this study was to compare the acute effects of single CA and CT stretching on various muscle and tendon mechanical properties. Seventeen young, healthy volunteers were tested on two separate days using either CT or CA stretching (4 × 30 s each). Before and after stretching, dorsiflexion range of motion (RoM), passive resistive torque (PRT), and maximum voluntary contraction (MVC) were measured with a dynamometer. Ultrasonography of the medial gastrocnemius (GM) muscle-tendon junction (MTJ) displacement allowed us to determine the length changes in the tendon and muscle, respectively, and hence to calculate their stiffness. Maximum dorsiflexion increased while PRT, muscle-tendon stiffness, and muscle stiffness decreased following both CA and CT stretching. There was a greater increase in RoM following CT stretching compared to CA stretching. Moreover, the decline in PRT was greater during CT stretching compared to CA stretching. As expected, several functional adaptations (RoM, PRT) were different between CT and CA stretching due to the higher intensity of CT stretching. However, no structural differences in the adaptations to the stretching modalities could be detected. We suggest that the different functional adaptations between CA and CT stretching are the consequence of different adaptations in the perception of stretch and pain.

  19. Glutaraldehyde Cross-Linking of TendonMechanical Effects at the Level of the Tendon Fascicle and Fibril

    DEFF Research Database (Denmark)

    Hansen, P.; Svensson, R.B.; Aagaard, P.

    2009-01-01

    Conclusive insight into the microscopic principles that govern the strength of tendon and related connective tissues is lacking and the importance of collagen cross-linking has not been firmly established. The combined application of whole-tissue mechanical testing and atomic force spectroscopy...

  20. Study of optical properties and proteoglycan content of tendons by polarization sensitive optical coherence tomography

    Science.gov (United States)

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

    2012-08-01

    The highly orientated collagen fibers in tendons play a critical role for transferring tensile stress, and they demonstrate birefringent optical properties. However, the influence that proteoglycans (PGs) have on the optical properties of tendons is yet to be fully elucidated. PGs are the essential components of the tendon extracellular matrix; the changes in their quantities and compositions have been associated with tendinopathies. In this study, polarization sensitive optical coherence tomography (PS-OCT) has been used to reveal the relationship between PG content/location and birefringence properties of tendons. Fresh chicken tendons were imaged at regular intervals by PS-OCT and polarization light microscopy during the extraction of PGs, using guanidine hydrochloride (GuHCl). Complementary time-lapsed images taken from the two modalities mutually demonstrated that the extraction of PGs disturbed the local organization of collagen bundles. This corresponded with a decrease in birefringence and associated banding pattern observed by PS-OCT. Furthermore, this study revealed there was a higher concentration of PGs in the outer sheath region than in the fascicles, and therefore the change in birefringence was reduced when extraction was performed on unsheathed tendons. The results provide new insights of tendon structure and the role of PGs on the structural stability of tendons, which also demonstrates the great potential for using PS-OCT as a diagnostic tool to examine tendon pathology.

  1. Development of Mechanical Anchor for CFRP Tendons Using Integrated Sleeve

    DEFF Research Database (Denmark)

    Schmidt, Jacob Wittrup; Bennitz, Anders; Täljsten, Björn

    2010-01-01

    A durable and very efficient external strengthening system is achieved if steel tendons for post-tensioning applications can be replaced with CFRP (Carbon Fibre Reinforced Polymer) tendons and if reliable anchorage systems are developed,. This paper presents a newly developed and simple-to-use tw...

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

    Science.gov (United States)

    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.

  3. Changes of calf muscle-tendon biomechanical properties induced by passive-stretching and active-movement training in children with cerebral palsy

    Science.gov (United States)

    Zhao, Heng; Wu, Yi-Ning; Hwang, Miriam; Ren, Yupeng; Gao, Fan; Gaebler-Spira, Deborah

    2011-01-01

    Biomechanical properties of calf muscles and Achilles tendon may be altered considerably in children with cerebral palsy (CP), contributing to childhood disability. It is unclear how muscle fascicles and tendon respond to rehabilitation and contribute to improvement of ankle-joint properties. Biomechanical properties of the calf muscle fascicles of both gastrocnemius medialis (GM) and soleus (SOL), including the fascicle length and pennation angle in seven children with CP, were evaluated using ultrasonography combined with biomechanical measurements before and after a 6-wk treatment of passive-stretching and active-movement training. The passive force contributions from the GM and SOL muscles were separated using flexed and extended knee positions, and fascicular stiffness was calculated based on the fascicular force-length relation. Biomechanical properties of the Achilles tendon, including resting length, cross-sectional area, and stiffness, were also evaluated. The 6-wk training induced elongation of muscle fascicles (SOL: 8%, P = 0.018; GM: 3%, P = 0.018), reduced pennation angle (SOL: 10%, P = 0.028; GM: 5%, P = 0.028), reduced fascicular stiffness (SOL: 17%, P = 0.128; GM: 21%, P = 0.018), decreased tendon length (6%, P = 0.018), increased Achilles tendon stiffness (32%, P = 0.018), and increased Young's modulus (20%, P = 0.018). In vivo characterizations of calf muscles and Achilles tendon mechanical properties help us better understand treatment-induced changes of calf muscle-tendon and facilitate development of more effective treatments. PMID:21596920

  4. Radioprotection provides functional mechanics but delays healing of irradiated tendon allografts after ACL reconstruction in sheep.

    Science.gov (United States)

    Seto, Aaron U; Culp, Brian M; Gatt, Charles J; Dunn, Michael

    2013-12-01

    Successful protection of tissue properties against ionizing radiation effects could allow its use for terminal sterilization of musculoskeletal allografts. In this study we functionally evaluate Achilles tendon allografts processed with a previously developed radioprotective treatment based on (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide) crosslinking and free radical scavenging using ascorbate and riboflavin, for ovine anterior cruciate ligament reconstruction. Arthroscopic anterior cruciate ligament (ACL) reconstruction was performed using double looped allografts, while comparing radioprotected irradiated and fresh frozen allografts after 12 and 24 weeks post-implantation, and to control irradiated grafts after 12 weeks. Radioprotection was successful at preserving early subfailure mechanical properties comparable to fresh frozen allografts. Twelve week graft stiffness and anterior-tibial (A-T) translation for radioprotected and fresh frozen allografts were comparable at 30 % of native stiffness, and 4.6 and 5 times native A-T translation, respectively. Fresh frozen allograft possessed the greatest 24 week peak load at 840 N and stiffness at 177 N/mm. Histological evidence suggested a delay in tendon to bone healing for radioprotected allografts, which was reflected in mechanical properties. There was no evidence that radioprotective treatment inhibited intra-articular graft healing. This specific radioprotective method cannot be recommended for ACL reconstruction allografts, and data suggest that future efforts to improve allograft sterilization procedures should focus on modifying or eliminating the pre-crosslinking procedure.

  5. Combined Effects of Scaffold Stiffening and Mechanical Preconditioning Cycles on Construct Biomechanics, Gene Expression, and Tendon Repair Biomechanics

    OpenAIRE

    Nirmalanandhan, Victor Sanjit; Juncosa-Melvin, Natalia; Shearn, Jason T.; Boivin, Gregory P; Galloway, Marc T.; Gooch, Cynthia; Bradica, Gino; Butler, David L.

    2009-01-01

    Our group has previously reported that in vitro mechanical stimulation of tissue-engineered tendon constructs significantly increases both construct stiffness and the biomechanical properties of the repair tissue after surgery. When optimized using response surface methodology, our results indicate that a mechanical stimulus with three components (2.4% strain, 3000 cycles/day, and one cycle repetition) produced the highest in vitro linear stiffness. Such positive correlations between construc...

  6. A rare knee extensor mechanism injury: Vastus intermedius tendon rupture

    Directory of Open Access Journals (Sweden)

    Engin Cetinkaya

    2015-01-01

    Conclusion: We report the first case of isolated rupture of the vastus intermedius tendon in the literature and we claim that disorder may be succesfully treated with conservative treatment and adequate physiotheraphy.

  7. The wrinkled patellar tendon: An indication of abnormality in the extensor mechanism of the knee

    Energy Technology Data Exchange (ETDEWEB)

    Berlin, R.C.; Levinsohn, E.M. (State Univ. of New York, Syracuse, NY (USA). Dept. of Radiology); Chrisman, H. (State Univ. of New York, Syracuse, NY (USA). Coll. of Medicine)

    1991-04-01

    Rupture of the quadriceps tendon is an uncommon condition which requires early diagnosis and treatment to avert prolonged disability. In four patients who had surgically confirmed quadriceps tendon rupture, lateral radiographs of the knee and/or sagittal magnetic resonance (MR) images demonstrated a corrugated appearance to the patellar tendon. Sagittal MR images of the knee following patellectomy in one patient and radiographs of a transverse fracture of the patella in another also demonstrated this appearance. MRI has superb contrast resolution which provides optimal visualization of the contour of the patellar tendon on sagittal images. A retrospective review of 50 consecutive knee MRI examinations was carried out to evaluate the appearance of the normal patellar tendon. In 49 of 50 patients, the sagittal images demonstrated a straight or nearly straight patellar tendon. A corrugated appearance of the patellar tendon on sagittal images indicates a reduction in the normal tensile force applied to it and indicates the need for careful evaluation of the patella and quadriceps tendon mechanism. (orig.).

  8. Alteration of the material properties of the normal supraspinatus tendon by nicotine treatment in a rat model.

    Science.gov (United States)

    Ichinose, Ryogo; Sano, Hirotaka; Kishimoto, Koshi N; Sakamoto, Naoya; Sato, Masaaki; Itoi, Eiji

    2010-10-01

    Several studies have shown that nicotine has a detrimental effect on the development of rotator cuff tear. However, little is known about its mechanism. We evaluated the effect of nicotine on the maximum tensile load, the maximum tensile stress, and the elastic modulus of the supraspinatus tendon in a rat model. 27 rats were randomly assigned to 3 groups. Subcutaneously implanted osmotic pumps delivered two different concentrations of nicotine solution (high dose: 45 ng/mL; low dose: 22.5 ng/mL) or saline solution (controls) over a 12-week period. The level of serum cotinine, a breakdown product of nicotine, was evaluated. We performed tensile testing using the left supraspinatus tendon in each rat. The maximum load of the supraspinatus tendon was measured, and the maximum tensile stress and elastic modulus were calculated. Serum cotinine levels showed controlled systemic release of nicotine. The maximum tensile load and stress were similar in the three groups. The elastic modulus was, however, higher in the nicotine groups than in the control group. In a rat model, nicotine caused a change in the material properties of the supraspinatus tendon. This change may predispose to a tear in the supraspinatus tendon.

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

    Science.gov (United States)

    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

  10. Characterization of differential properties of rabbit tendon stem cells and tenocytes

    Directory of Open Access Journals (Sweden)

    Wang James

    2010-01-01

    Full Text Available Abstract Background Tendons are traditionally thought to consist of tenocytes only, the resident cells of tendons; however, a recent study has demonstrated that human and mouse tendons also contain stem cells, referred to as tendon stem/progenitor cells (TSCs. However, the differential properties of TSCs and tenocytes remain largely undefined. This study aims to characterize the properties of these tendon cells derived from rabbits. Methods TSCs and tenocytes were isolated from patellar and Achilles tendons of rabbits. The differentiation potential and cell marker expression of the two types of cells were examined using histochemical, immunohistochemical, and qRT-PCR analysis as well as in vivo implantation. In addition, morphology, colony formation, and proliferation of TSCs and tenocytes were also compared. Results It was found that TSCs were able to differentiate into adipocytes, chondrocytes, and osteocytes in vitro, and form tendon-like, cartilage-like, and bone-like tissues in vivo. In contrast, tenocytes had little such differentiation potential. Moreover, TSCs expressed the stem cell markers Oct-4, SSEA-4, and nucleostemin, whereas tenocytes expressed none of these markers. Morphologically, TSCs possessed smaller cell bodies and larger nuclei than ordinary tenocytes and had cobblestone-like morphology in confluent culture whereas tenocytes were highly elongated. TSCs also proliferated more quickly than tenocytes in culture. Additionally, TSCs from patellar tendons formed more numerous and larger colonies and proliferated more rapidly than TSCs from Achilles tendons. Conclusions TSCs exhibit distinct properties compared to tenocytes, including differences in cell marker expression, proliferative and differentiation potential, and cell morphology in culture. Future research should investigate the mechanobiology of TSCs and explore the possibility of using TSCs to more effectively repair or regenerate injured tendons.

  11. Altered Biomechanical Properties of Gastrocnemius Tendons of Turkeys Infected with Turkey Arthritis Reovirus

    Directory of Open Access Journals (Sweden)

    Tamer A. Sharafeldin

    2016-01-01

    Full Text Available Turkey arthritis reovirus (TARV causes lameness and tenosynovitis in commercial turkeys and is often associated with gastrocnemius tendon rupture by the marketing age. This study was undertaken to characterize the biomechanical properties of tendons from reovirus-infected turkeys. One-week-old turkey poults were orally inoculated with O’Neil strain of TARV and observed for up to 16 weeks of age. Lameness was first observed at 8 weeks of age, which continued at 12 and 16 weeks. At 4, 8, 12, and 16 weeks of age, samples were collected from legs. Left intertarsal joint with adjacent gastrocnemius tendon was collected and processed for histological examination. The right gastrocnemius tendon’s tensile strength and elasticity modulus were analyzed by stressing each tendon to the point of rupture. At 16 weeks of age, gastrocnemius tendons of TARV-infected turkeys showed significantly reduced (P<0.05 tensile strength and modulus of elasticity as compared to those of noninfected control turkeys. Gastrocnemius tendons revealed lymphocytic tendinitis/tenosynovitis beginning at 4 weeks of age, continuing through 8 and 12 weeks, and progressing to fibrosis from 12 to 16 weeks of age. We propose that tendon fibrosis is one of the key features contributing to reduction in tensile strength and elasticity of gastrocnemius tendons in TARV-infected turkeys.

  12. Mechanical anchorage of FRP tendons – A literature review

    DEFF Research Database (Denmark)

    Schmidt, Jacob W.; Bennitz, Anders; Täljsten, Björn

    2012-01-01

    High tensile strength, good resistance to degradation and creep, low weight and, to some extent, the ability to change the modulus of elasticity are some of the advantages of using prestressed, unidirectional FRP (Fibre Reinforced Polymer) tendon systems. Bonded and non-bonded versions of these s......High tensile strength, good resistance to degradation and creep, low weight and, to some extent, the ability to change the modulus of elasticity are some of the advantages of using prestressed, unidirectional FRP (Fibre Reinforced Polymer) tendon systems. Bonded and non-bonded versions...... with such systems. This is especially important in external post-tensioned tendon systems, where the anchorage points are exposed to the full load throughout the life span of the structure. Consequently, there are large requirements related to the long-term capacity and fatigue resistance of such systems. Several...... anchorage systems for use with Aramid, Glass and Carbon FRP tendons have been proposed over the last two decades. Each system is usually tailored to a particular type of tendon. This paper presents a brief overview of bonded anchorage applications while the primary literature review discusses three methods...

  13. Mechanical Loading Improves Tendon-Bone Healing in a Rabbit Anterior Cruciate Ligament Reconstruction Model by Promoting Proliferation and Matrix Formation of Mesenchymal Stem Cells and Tendon Cells

    Directory of Open Access Journals (Sweden)

    Fanglong Song

    2017-02-01

    Full Text Available Background/Aims: This study investigated the effect of mechanical stress on tendon-bone healing in a rabbit anterior cruciate ligament (ACL reconstruction model as well as cell proliferation and matrix formation in co-culture of bone-marrow mesenchymal stem cells (BMSCs and tendon cells (TCs. Methods: The effect of continuous passive motion (CPM therapy on tendon-bone healing in a rabbit ACL reconstruction model was evaluated by histological analysis, biomechanical testing and gene expressions at the tendon-bone interface. Furthermore, the effect of mechanical stretch on cell proliferation and matrix synthesis in BMSC/TC co-culture was also examined. Results: Postoperative CPM therapy significantly enhanced tendon-bone healing, as evidenced by increased amount of fibrocartilage, elevated ultimate load to failure levels, and up-regulated gene expressions of Collagen I, alkaline phosphatase, osteopontin, Tenascin C and tenomodulin at the tendon-bone junction. In addition, BMSC/TC co-culture treated with mechanical stretch showed a higher rate of cell proliferation and enhanced expressions of Collagen I, Collagen III, alkaline phosphatase, osteopontin, Tenascin C and tenomodulin than that of controls. Conclusion: These results demonstrated that proliferation and differentiation of local precursor cells could be enhanced by mechanical stimulation, which results in enhanced regenerative potential of BMSCs and TCs in tendon-bone healing.

  14. Inhibitory mechanisms following electrical stimulation of tendon and cutaneous afferents in the lower limb.

    Science.gov (United States)

    Khan, Serajul I; Burne, John A

    2010-01-13

    Electrical stimulation of the Achilles tendon (TES) produced strong reflex depression (duration>250 ms) of a small background contraction in both heads of gastrocnemius (GA) via large diameter electrodes localized to the tendon. The inhibitory responses were produced without electrical (M wave) or mechanical (muscle twitch) signs of direct muscle stimulation. In this study, the contribution of presynaptic and postsynaptic mechanisms to the depression was investigated by studying conditioning effects of tendon afferent stimulation on the mechanical tendon reflex (TR) and magnetic motor evoked potential (MEP). TES completely inhibited the TR over an ISI of 300 ms that commenced before and continued during and after the period of voluntary EMG depression. Tendon afferent conditioning stimuli also partially inhibited the MEP, but over a short time course confined to the period of voluntary EMG depression. The strength and extended time course of tendon afferent conditioning of the TR and its failure to produce a similar depression of the MEP are consistent with a mechanism involving presynaptic inhibition of Ia terminals. Cutaneous (sural nerve) afferent conditioning partially inhibited the TR and MEP over a short time course (ISI origin of cutaneous inhibition of the motoneurons.

  15. Effect of the Position of Immobilization Upon the Tensile Properties in Injured Achilles Tendon of Rat

    Science.gov (United States)

    Min, Yong; Kwon, Young-Bae; Lee, Min-Ho

    2013-01-01

    Objective To examine the effect of the posture of immobilization upon the tensile properties in injured Achilles tendon of rat for an initial period of immobilization. Methods Forty-two Sprague-Dawley rats were used in the present study. Eighteen rats received a total tenotomy of the right Achilles tendon to mimic total rupture and were divided into three groups comprising of 6 rats each. Ankles of group A were immobilized at 60° of plantarflexion. Ankles of group B were immobilized at neutral position. Whereas, those of group C were immobilized at 60° of dorsiflexion. Other 18 rats received hemitenotomy to mimic partial rupture and were divided into three groups. The remaining 6 rats were kept free as control. After 14 days, we dissected the tendons and analyzed maximum force, stiffness, and energy uptake during pulling of the tendons until they ruptured. The tendons of 6 rats in each group and control were reserved for histology. Picrosirius staining was done for the analysis of collagen organization. Results In total tenotomy, tensile properties were significantly different between the control and the intervention groups (p0.05). In partial tenotomy, tensile properties were significantly different between the control and the intervention groups (pdorsiflexion posture were higher than the ones for plantarflexion. Conclusion Dorsiflexion posture in partial ruptured Achilles tendon showed better functional recovery than other immobilized postures. In total ruptured case, the tensile properties showed increasing tendency in dorsiflexion posture. PMID:23525566

  16. Muscle-tendon mechanics explain unexpected effects of exoskeleton assistance on metabolic rate during walking.

    Science.gov (United States)

    Jackson, Rachel W; Dembia, Christopher L; Delp, Scott L; Collins, Steven H

    2017-06-01

    The goal of this study was to gain insight into how ankle exoskeletons affect the behavior of the plantarflexor muscles during walking. Using data from previous experiments, we performed electromyography-driven simulations of musculoskeletal dynamics to explore how changes in exoskeleton assistance affected plantarflexor muscle-tendon mechanics, particularly for the soleus. We used a model of muscle energy consumption to estimate individual muscle metabolic rate. As average exoskeleton torque was increased, while no net exoskeleton work was provided, a reduction in tendon recoil led to an increase in positive mechanical work performed by the soleus muscle fibers. As net exoskeleton work was increased, both soleus muscle fiber force and positive mechanical work decreased. Trends in the sum of the metabolic rates of the simulated muscles correlated well with trends in experimentally observed whole-body metabolic rate (R2=0.9), providing confidence in our model estimates. Our simulation results suggest that different exoskeleton behaviors can alter the functioning of the muscles and tendons acting at the assisted joint. Furthermore, our results support the idea that the series tendon helps reduce positive work done by the muscle fibers by storing and returning energy elastically. We expect the results from this study to promote the use of electromyography-driven simulations to gain insight into the operation of muscle-tendon units and to guide the design and control of assistive devices. © 2017. Published by The Company of Biologists Ltd.

  17. Biomechanical properties of Achilles tendon repair augmented with a bioadhesive-coated scaffold.

    Science.gov (United States)

    Brodie, Michael; Vollenweider, Laura; Murphy, John L; Xu, Fangmin; Lyman, Arinne; Lew, William D; Lee, Bruce P

    2011-02-01

    The Achilles tendon is the most frequently ruptured tendon. Both acute and chronic (neglected) tendon ruptures can dramatically affect a patient's quality of life, and require a prolonged period of recovery before return to pre-injury activity levels. This paper describes the use of an adhesive-coated biologic scaffold to augment primary suture repair of transected Achilles tendons. The adhesive portion consisted of a synthetic mimic of mussel adhesive proteins that can adhere to various surfaces in a wet environment, including biologic tissues. When combined with biologic scaffolds such as bovine pericardium or porcine dermal tissues, these adhesive constructs demonstrated lap shear adhesive strengths significantly greater than that of fibrin glue, while reaching up to 60% of the strength of a cyanoacrylate-based adhesive. These adhesive constructs were wrapped around transected cadaveric porcine Achilles tendons repaired with a combination of parallel and three-loop suture patterns. Tensile mechanical testing of the augmented repairs exhibited significantly higher stiffness (22-34%), failure load (24-44%), and energy to failure (27-63%) when compared to control tendons with suture repair alone. Potential clinical implications of this novel adhesive biomaterial are discussed.

  18. Biomechanical properties of Achilles tendon repair augmented with a bioadhesive-coated scaffold

    Energy Technology Data Exchange (ETDEWEB)

    Brodie, Michael; Vollenweider, Laura; Murphy, John L; Xu Fangmin; Lyman, Arinne; Lew, William D; Lee, Bruce P, E-mail: b-lee@nerites.com [Nerites Corporation, 505 S. Rosa Road, Suite 123, Madison, WI 53719 (United States)

    2011-02-15

    The Achilles tendon is the most frequently ruptured tendon. Both acute and chronic (neglected) tendon ruptures can dramatically affect a patient's quality of life, and require a prolonged period of recovery before return to pre-injury activity levels. This paper describes the use of an adhesive-coated biologic scaffold to augment primary suture repair of transected Achilles tendons. The adhesive portion consisted of a synthetic mimic of mussel adhesive proteins that can adhere to various surfaces in a wet environment, including biologic tissues. When combined with biologic scaffolds such as bovine pericardium or porcine dermal tissues, these adhesive constructs demonstrated lap shear adhesive strengths significantly greater than that of fibrin glue, while reaching up to 60% of the strength of a cyanoacrylate-based adhesive. These adhesive constructs were wrapped around transected cadaveric porcine Achilles tendons repaired with a combination of parallel and three-loop suture patterns. Tensile mechanical testing of the augmented repairs exhibited significantly higher stiffness (22-34%), failure load (24-44%), and energy to failure (27-63%) when compared to control tendons with suture repair alone. Potential clinical implications of this novel adhesive biomaterial are discussed.

  19. Plantarflexor Muscle Tendon Properties are Associated With Mobility in Healthy Older Adults

    OpenAIRE

    Stenroth, Lauri; Sillanpää, Elina; McPhee, Jamie S.; Narici, Marco V.; Gapeyeva, Helena; Pääsuke, Mati; Barnouin, Yoann; Hogrel, Jean-Yves; Butler-Browne, Gillian; Bijlsma, Astrid; Meskers, Carel G. M.; Maier, Andrea B.; Finni Juutinen, Taija; Sipilä, Sarianna

    2015-01-01

    Background. Muscle mass, strength, and power are known determinants of mobility in older adults but there is limited knowledge on the influence of muscle architecture or tendon properties on mobility. The purpose of this study was to examine the relationship between mobility and plantarflexor muscle–tendon properties in healthy older adults. Methods. A total of 52 subjects (age 70–81 years) were measured for 6-minute walk test (6MWT), timed “up and go”-test (TUG), isometric pla...

  20. Biomechanical properties of isolated fascicles of the Iliopsoas and Achilles tendons in African American and Caucasian men

    DEFF Research Database (Denmark)

    Hanson, P; Aagaard, P; Magnusson, S P

    2012-01-01

    To investigate biomechanical properties of the Iliopsoas and Achilles tendons in young African American (AA) and Caucasian (CC) men, and attempt to clarify whether the difference in Achilles tendon ruptures between AA and CC can be explained by differences in material properties....

  1. Tenomodulin is Required for Tendon Endurance Running and Collagen I Fibril Adaptation to Mechanical Load

    Directory of Open Access Journals (Sweden)

    Sarah Dex

    2017-06-01

    Full Text Available Tendons are dense connective tissues that attach muscles to bone with an indispensable role in locomotion because of their intrinsic properties of storing and releasing muscle- generated elastic energy. Tenomodulin (Tnmd is a well-accepted gene marker for the mature tendon/ligament lineage and its loss-of -function in mice leads to a phenotype with distinct signs of premature aging on tissue and stem/progenitor cell levels. Based on these findings, we hypothesized that Tnmd might be an important factor in the functional performance of tendons. Firstly, we revealed that Tnmd is a mechanosensitive gene and that the C-terminus of the protein co-localize with collagen I-type fibers in the extracellular matrix. Secondly, using an endurance training protocol, we compared Tnmd knockout mice with wild types and showed that Tnmd deficiency leads to significantly inferior running performance that further worsens with training. In these mice, endurance running was hindered due to abnormal response of collagen I cross-linking and proteoglycan genes leading to an inadequate collagen I fiber thickness and elasticity. In sum, our study demonstrates that Tnmd is required for proper tendon tissue adaptation to endurance running and aids in better understanding of the structural-functional relationships of tendon tissues.

  2. Microtrauma stimulates rat Achilles tendon healing via an early gene expression pattern similar to mechanical loading

    DEFF Research Database (Denmark)

    Hammerman, Malin; Aspenberg, Per; Eliasson, Pernilla

    2014-01-01

    rats received Botox into the calf muscle to reduce loading, and the Achilles tendon was transected. Ten rats were randomized to needling days 2-5. Mechanical testing on day 8 showed increased strength by 45% in the needling group. Next, another 24 rats were similarly unloaded, and 16 randomized...

  3. Plantarflexor Muscle-Tendon Properties are Associated With Mobility in Healthy Older Adults

    NARCIS (Netherlands)

    Stenroth, L.; Sillanpaa, E.; McPhee, J.S.; Narici, M.V.; Gapeyeva, H.; Paasuke, M.; Barnouin, Y.; Hogrel, J.Y.; Butler-Browne, G.; Bijlsma, A.; Meskers, C.G.M.; Maier, A.B.; Finni, T.; Sipila, S.

    2015-01-01

    Background. Muscle mass, strength, and power are known determinants of mobility in older adults but there is limited knowledge on the influence of muscle architecture or tendon properties on mobility. The purpose of this study was to examine the relationship between mobility and plantarflexor

  4. The effects of substance P on the biomechanic properties of ruptured rat Achilles' tendon.

    Science.gov (United States)

    Steyaert, Adelheid E; Burssens, Peter J; Vercruysse, Chris W; Vanderstraeten, Guy G; Verbeeck, Ronald M

    2006-02-01

    To determine whether injection of substance P into the paratendinous region of a ruptured and subsequently sutured rat Achilles' tendon alters the biomechanic properties of the tendon. Interventional animal study. Animal laboratory at a university hospital. Ninety-six 2-month-old, male Sprague-Dawley rats. Injection of saline, substance P (10(-6)micromol/kg of body weight [BW] or 10(-8)micromol/kg BW) associated with neutral endopeptidase inhibitors, or neutral endopeptidase inhibitors alone into the paratendinous region of ruptured and subsequently sutured rat Achilles' tendons from the second until the sixth day postoperatively. Stress at maximal load and work to maximal load and stiffness. Stress at maximal load was higher in the groups injected with substance P than in the saline group in the first, second, and sixth weeks. Work to maximal load was higher from the second until the sixth weeks in the substance P-treated groups than in the saline group. Stiffness did not differ between the 4 groups in any of the weeks. Injection of substance P into the paratendinous region of ruptured and subsequently sutured rat Achilles' tendons improved tendon healing by enhancing stress at maximal load and work to maximal load. However, stiffness was not significantly affected.

  5. Alpine Skiing With total knee ArthroPlasty (ASWAP): effect on tendon properties.

    Science.gov (United States)

    Kösters, A; Rieder, F; Wiesinger, H-P; Dorn, U; Hofstaedter, T; Fink, C; Müller, E; Seynnes, O R

    2015-08-01

    The aim of this study was to investigate the effect of alpine skiing on patellar tendon properties in patients with total knee arthroplasty (TKA). Thirty-one adults (70.4 ± 4.7 years) with unilateral TKA were recruited 2.7 ± 0.9 years after surgery and assigned to an intervention (IG) or a control group (CG). The IG underwent a 12-week guided skiing program. Tendon stiffness, Young's modulus, and cross-sectional area (CSA) were measured before and after the intervention. In both groups, mean tendon CSA was 28% (P alpine skiing appears to offer a suitable rehabilitation strategy for TKA patients. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

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

    Science.gov (United States)

    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.

  7. Tendon biomechanics and mechanobiology - a mini-review of basic concepts and recent advancements

    Science.gov (United States)

    Wang, James H-C.; Guo, Qianping; Li, Bin

    2011-01-01

    Due to their unique hierarchical structure and composition, tendons possess characteristic biomechanical properties, including high mechanical strength and viscoelasticity, which enable them to carry and transmit mechanical loads (muscular forces) effectively. Tendons are also mechano-responsive by adaptively changing their structure and function in response to altered mechanical loading conditions. In general, mechanical loading at physiological levels is beneficial to tendons, but excessive loading or disuse of tendons is detrimental. This mechano-adaptability is due to the cells present in tendons. Tendon fibroblasts (tenocytes) are the dominant tendon cells responsible for tendon homeostasis and repair. Tendon stem cells (TSCs), which were recently discovered, also play a vital role in tendon maintenance and repair by virtue of their ability to self-renew and differentiate into tenocytes. TSCs may also be responsible for chronic tendon injury, or tendinopathy, by undergoing aberrant differentiation into non-tenocytes in response to excessive mechanical loading. Thus, it is necessary to devise optimal rehabilitation protocols in order to enhance tendon healing while reducing scar tissue formation and tendon adhesions. Moreover, along with scaffolds that can mimic tendon matrix environments and platelet-rich plasma (PRP), which serves as a source of growth factors, TSCs may be the optimal cell type for enhancing repair of injured tendons. PMID:21925835

  8. [ISOLATION OF RAT PATELLAR TENDON STEM CELLS AND EFFECT OF MECHANICAL STRETCHING ON Sox-9 EXPRESSION].

    Science.gov (United States)

    Qin, Shengnan; Wang, Wen; Fu, Shiquan; Cheng, Yushan; Chen, Honghui; Dong, Fei; Chen, Qiming; Li, Aiguo

    2015-07-01

    To isolate the tendon stem cells (TSCs) from rat patellar tendon and to investigate the effect of mechanical stretching on the expression of Sox-9. TSCs were isolated from Sprague Dawley rat (12 weeks old) patellar tendon by collagenase digestion and low density culture. The cell colony morphology and number were observed by crystal violet staining; the cell morphology was observed by inverted phase contrast microscope, and the immunophenotypes of mesenchymal stem cells (MSCs) were determined by flow cytometry. The TSCs at passage 3 was given the mechanical stretching at 4%, 0.17 Hz for 4 hours and 24 hours in the experimental group, and cells without stretching was used as control. The Sox-9 gene and protein expressions were detected by real-time fluorescence quantitative PCR and Western blot. Primary cells showed clonal growth and star shape; after subculture, cells at passage 1 showed fibroblast-like shape. The cells formed cell colonies after 7 days; the expressions were positive for CD29, CD44, and CD90 and negative for CD45. The result of real-time fluorescence quantitative PCR showed that Sox-9 gene was down-regulated at 4 hours after mechanical stretching compared with control (P Sox-9 protein expression was lower at 4 hours after stretching, but higher at 24 hours after mechanical stretching than that in control group (P Sox-9 expression, but the inhibited effect might stimulate the Sox-9 expression after the mechanical stretching effect disappears.

  9. Biocompatibility and strength properties of nitinol shape memory alloy suture in rabbit tendon.

    Science.gov (United States)

    Kujala, Sauli; Pajala, Ari; Kallioinen, Matti; Pramila, Antti; Tuukkanen, Juha; Ryhänen, Jorma

    2004-01-01

    Nitinol (NiTi) is a promising new tendon suture material with good strength, easy handling and good super-elastic properties. NiTi sutures were implanted for biocompatibility testing into the right medial gastrocnemius tendon in 15 rabbits for 2, 6 and 12 weeks. Additional sutures were implanted in subcutaneous tissue for strength measurements in order to determine the effect of implantation on strength properties of NiTi suture material. Braided polyester sutures (Ethibond) of approximately the same diameter were used as control. Encapsulating membrane formation around the sutures was minimal in the case of both materials. The breaking load of NiTi was significantly greater compared to braided polyester. Implantation did not affect the strength properties of either material.

  10. A longitudinal assessment of running economy and tendon properties in long-distance runners.

    Science.gov (United States)

    Kubo, Keitaro; Tabata, Tomonori; Ikebukuro, Toshihiro; Igarashi, Katsumi; Tsunoda, Naoya

    2010-07-01

    The aim of this study was to investigate longitudinal changes in tendon properties and running economy of long-distance runners (LDRs) in the preparatory periods of track season (TS) and road season (RS). Eleven well-trained LDRs and 6 untrained subjects participated in the present study. In each period, muscle strength, neural activation level, and tendon elongation for both knee extensors and plantar flexors, jump performances, and oxygen consumption during submaximal running velocities were measured. No significant differences observed in any measured variables between the 2 seasons for untrained subjects. For LDRs, the total running distance during 1 month preceding RS (832 +/- 95 km) was significantly longer than that during 1 month preceding TS (718 +/- 80 km). No significant differences in the muscle strength, neural activation level, and jump performances were found between TS and RS. The stiffness of tendon structures in RS was significantly lower than those in TS for both knee extensors (-14.4%, p = 0.023) and plantar flexors (-16.6%, p = 0.040). At 3 running velocities, the oxygen consumptions in RS were significantly lower than those in TS. These results suggested that the lower oxygen consumption during submaximal running velocities observed in the preparatory period of RS may be attributable to the more compliant tendon structures but not in the neuromuscular characteristics.

  11. Viscoelastic Properties of Healthy Achilles Tendon are Independent of Isometric Plantar Flexion Strength and Cross-Sectional Area

    Science.gov (United States)

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

    2015-01-01

    Changes in tendon viscoelastic properties are observed after injuries and during healing as a product of altered composition and structure. Continuous Shear Wave Elastography is a new technique measuring viscoelastic properties of soft tissues using external shear waves. Tendon has not been studied with this technique, therefore, the aims of this study were to establish the range of shear and viscosity moduli in healthy Achilles tendons, determine bilateral differences of these parameters and explore correlations of viscoelasticity to plantar flexion strength and tendon area. Continuous Shear Wave Elastography was performed over the free portion of both Achilles tendons from 29 subjects. Isometric plantar flexion strength and cross sectional area were measured. The average shear and viscous moduli was 83.2kPa and 141.0Pa-s, respectively. No correlations existed between the shear or viscous modulus and area or strength. This indicates that viscoelastic properties can be considered novel, independent biomarkers. The shear and viscosity moduli were bilaterally equivalent (p=0.013,0.017) which allows determining pathologies through side-to-side deviations. The average bilateral coefficient of variation was 7.2% and 9.4% for shear and viscosity modulus, respectively. The viscoelastic properties of the Achilles tendon may provide an unbiased, non-subjective rating system of tendon recovery and optimizing treatment strategies. PMID:25882209

  12. Augmentation of Distal Biceps Repair With an Acellular Dermal Graft Restores Native Biomechanical Properties in a Tendon-Deficient Model.

    Science.gov (United States)

    Conroy, Christine; Sethi, Paul; Macken, Craig; Wei, David; Kowalsky, Marc; Mirzayan, Raffy; Pauzenberger, Leo; Dyrna, Felix; Obopilwe, Elifho; Mazzocca, Augustus D

    2017-07-01

    -deficient, complete distal biceps rupture model, acellular dermal allograft augmentation restored the native tendon's biomechanical properties at time zero. The grafted tissue-deficient model demonstrated no significant differences in the load to failure and gap formation compared with the native tendon. As expected, dermal augmentation of attritional tendon repair increased the load to failure and stiffness as well as decreased displacement compared with the ungrafted tissue-deficient model. Tendons with their native width showed no statistical difference or negative biomechanical consequences of dermal augmentation. Dermal augmentation of the distal biceps is a biomechanically feasible option for patients with an attritionally thinned-out tendon.

  13. Combined effects of scaffold stiffening and mechanical preconditioning cycles on construct biomechanics, gene expression, and tendon repair biomechanics.

    Science.gov (United States)

    Nirmalanandhan, Victor Sanjit; Juncosa-Melvin, Natalia; Shearn, Jason T; Boivin, Gregory P; Galloway, Marc T; Gooch, Cynthia; Bradica, Gino; Butler, David L

    2009-08-01

    Our group has previously reported that in vitro mechanical stimulation of tissue-engineered tendon constructs significantly increases both construct stiffness and the biomechanical properties of the repair tissue after surgery. When optimized using response surface methodology, our results indicate that a mechanical stimulus with three components (2.4% strain, 3000 cycles/day, and one cycle repetition) produced the highest in vitro linear stiffness. Such positive correlations between construct and repair stiffness after surgery suggest that enhancing structural stiffness before surgery could not only accelerate repair stiffness but also prevent premature failures in culture due to poor mechanical integrity. In this study, we examined the combined effects of scaffold crosslinking and subsequent mechanical stimulation on construct mechanics and biology. Autologous tissue-engineered constructs were created by seeding mesenchymal stem cells (MSCs) from 15 New Zealand white rabbits on type I collagen sponges that had undergone additional dehydrothermal crosslinking (termed ADHT in this manuscript). Both constructs from each rabbit were mechanically stimulated for 8h/day for 12 consecutive days with half receiving 100 cycles/day and the other half receiving 3000 cycles/day. These paired MSC-collagen autologous constructs were then implanted in bilateral full-thickness, full-length defects in the central third of rabbit patellar tendons. Increasing the number of in vitro cycles/day delivered to the ADHT constructs in culture produced no differences in stiffness or gene expression and no changes in biomechanical properties or histology 12 weeks after surgery. Compared to MSC-based repairs from a previous study that received no additional treatment in culture, ADHT crosslinking of the scaffolds actually lowered the 12-week repair stiffness. Thus, while ADHT crosslinking may initially stiffen a construct in culture, this specific treatment also appears to mask any benefits

  14. Mechanical Properties of Polymers.

    Science.gov (United States)

    Aklonis, J. J.

    1981-01-01

    Mechanical properties (stress-strain relationships) of polymers are reviewed, taking into account both time and temperature factors. Topics include modulus-temperature behavior of polymers, time dependence, time-temperature correspondence, and mechanical models. (JN)

  15. p38 MAPK signaling in postnatal tendon growth and remodeling.

    Directory of Open Access Journals (Sweden)

    Andrew J Schwartz

    Full Text Available 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.

  16. [Molecular repair mechanisms using the Intratissue Percutaneous Electrolysis technique in patellar tendonitis].

    Science.gov (United States)

    Abat, F; Valles, S L; Gelber, P E; Polidori, F; Stitik, T P; García-Herreros, S; Monllau, J C; Sanchez-Ibánez, J M

    2014-01-01

    To investigate the molecular mechanisms of tissue response after treatment with the Intratissue Percutaneous Electrolysis (EPI(®)) technique in collagenase-induced tendinopathy in Sprague-Dawley rats. Tendinopathy was induced by injecting 50 μg of type i collagenase into the patellar tendon of 24 Sprague Dawley rats of 7 months of age and weighting 300 g. The sample was divided into 4 groups: the control group, collagenase group, and two EPI(®) technique treatment groups of 3 and 6 mA, respectively. An EPI(®) treatment session was applied, and after 3 days, the tendons were analysed using immunoblotting and electrophoresis techniques. An analysis was also made of cytochrome C protein, Smac/Diablo, vascular endothelial growth factor and its receptor 2, as well as the nuclear transcription factor peroxisome proliferator-activated receptor gamma. A statistically significant increase, compared to the control group, was observed in the expression of cytochrome C, Smac/Diablo, vascular endothelial growth factor, its receptor 2 and peroxisome proliferator-activated receptor gamma in the groups in which the EPI(®) technique was applied. EPI(®) technique produces an increase in anti-inflammatory and angiogenic molecular mechanisms in collagenase-induced tendon injury in rats. Copyright © 2013 SECOT. Published by Elsevier Espana. All rights reserved.

  17. An in vitro scratch tendon tissue injury model: effects of high frequency low magnitude loading.

    Science.gov (United States)

    Adekanmbi, Isaiah; Zargar, Nasim; Hulley, Philippa

    2017-03-01

    The healing process of ruptured tendons is suboptimal, taking months to achieve tissue with inferior properties to healthy tendon. Mechanical loading has been shown to positively influence tendon healing. However, high frequency low magnitude (HFLM) loads, which have shown promise in maintaining healthy tendon properties, have not been studied with in vitro injury models. Here, we present and validate an in vitro scratch tendon tissue injury model to investigate effects of HFLM loading on the properties of injured rat tail tendon fascicles (RTTFs). A longitudinal tendon tear was simulated using a needle aseptically to scratch a defined length along individual RTTFs. Tissue viability, biomechanical, and biochemical parameters were investigated before and 7 days after culture . The effects of static, HFLM (20 Hz), and low frequency (1 Hz) cyclic loading or no load were also investigated. Tendon viability was confirmed in damaged RTTFs after 7 days of culture, and the effects of a 0.77 ± 0.06 cm scratch on the mechanical property (tangent modulus) and tissue metabolism in damaged tendons were consistent, showing significant damage severity compared with intact tendons. Damaged tendon fascicles receiving HFLM (20 Hz) loads displayed significantly higher mean tangent modulus than unloaded damaged tendons (212.7 ± 14.94 v 92.7 ± 15.59 MPa), and damaged tendons receiving static loading (117.9 ± 10.65 MPa). HFLM stimulation maintained metabolic activity in 7-day cultured damaged tendons at similar levels to fresh tendons immediately following damage. Only damaged tendons receiving HFLM loads showed significantly higher metabolism than unloaded damaged tendons (relative fluorescence units -7021 ± 635.9 v 3745.1 ± 641.7). These validation data support the use of the custom-made in vitro injury model for investigating the potential of HFLM loading interventions in treating damaged tendons.

  18. Postinjury biomechanics of Achilles tendon vary by sex and hormone status

    Science.gov (United States)

    Fryhofer, George W.; Freedman, Benjamin R.; Hillin, Cody D.; Salka, Nabeel S.; Pardes, Adam M.; Weiss, Stephanie N.; Farber, Daniel C.

    2016-01-01

    Achilles tendon ruptures are common injuries. Sex differences are present in mechanical properties of uninjured Achilles tendon, but it remains unknown if these differences extend to tendon healing. We hypothesized that ovariectomized females (OVX) and males would exhibit inferior postinjury tendon properties compared with females. Male, female, and OVX Sprague-Dawley rats (n = 32/group) underwent acclimation and treadmill training before blunt transection of the Achilles tendon midsubstance. Injured hindlimbs were immobilized for 1 wk, followed by gradual return to activity and assessment of active and passive hindlimb function. Animals were euthanized at 3 or 6 wk postinjury to assess tendon structure, mechanics, and composition. Passive ankle stiffness and range of motion were superior in females at 3 wk; however, by 6 wk, passive and active function were similar in males and females but remained inferior in OVX. At 6 wk, female tendons had greater normalized secant modulus, viscoelastic behavior, and laxity compared with males. Normalized secant modulus, cross-sectional area and tendon glycosaminoglycan composition were inferior in OVX compared with females at 6 wk. Total fatigue cycles until tendon failure were similar among groups. Postinjury muscle fiber size was better preserved in females compared with males, and females had greater collagen III at the tendon injury site compared with males at 6 wk. Despite male and female Achilles tendons withstanding similar durations of fatigue loading, early passive hindlimb function and tendon mechanical properties, including secant modulus, suggest superior healing in females. Ovarian hormone loss was associated with inferior Achilles tendon healing. PMID:27633741

  19. Are the knee and ankle angles at contact related to the tendon properties of lower limbs in long distance runners?

    OpenAIRE

    Kubo, Keitaro; Miyazaki, Daisuke; Yamada, Kenji; Shimoju, Shozo; Tsunoda, Naoya

    2016-01-01

    The purpose of this study was to investigate whether the knee and ankle angles at contact during running were related to the elastic properties of tendon structures in knee extensors and plantar flexors and performance in trained long distance runners. Thirty-two highly trained male long distance runners participated in this study. Elongation of tendon structures in knee extensors and plantar flexors were measured using ultrasonography while subjects performed ramp isometric contractions up t...

  20. Suture anchor repair yields better biomechanical properties than transosseous sutures in ruptured quadriceps tendons.

    Science.gov (United States)

    Petri, M; Dratzidis, A; Brand, S; Calliess, T; Hurschler, C; Krettek, C; Jagodzinski, M; Ettinger, M

    2015-04-01

    This human cadaveric study compares the biomechanical properties of quadriceps tendon repair with suture anchors and the commonly applied transosseous sutures. The hypothesis was that suture anchors provide at least equal results concerning gap formation and ultimate failure load compared with transosseous suture repair. Thirty human cadaveric knees underwent tenotomy followed by repair with either 5.5-mm-double-loaded suture anchors [titanium (TA) vs. resorbable hydroxyapatite (HA)] or transpatellar suture tunnels using No. 2 Ultrabraid™ and the Krackow whipstitch. Biomechanical analysis included pretensioning the constructs with 20 N for 30 s and then cyclic loading of 250 cycles between 20 and 100 N at 1 Hz in a servohydraulic testing machine with measurement of elongation. Ultimate failure load analysis and failure mode analysis were performed subsequently. Tendon repairs with suture anchors yielded significantly less gap formation during cyclic loading (20th-250th cycle: TA 1.9 ± 0.1, HA 1.5 ± 0.5, TS 33.3 ± 1.9 mm, p sutures. Common failure mode was pull-out of the eyelet within the suture anchor in the HA group and rupture of the suture in the TA and TS group. Quadriceps tendon repair with suture anchors yields significantly better biomechanical results than the commonly applied transosseous sutures in this human cadaveric study. These biomechanical findings may change the future clinical treatment for quadriceps tendon ruptures. Randomised controlled clinical trials are desirable for the future. Not applicable, controlled laboratory human cadaveric study.

  1. Biomechanical and structural response of healing Achilles tendon to fatigue loading following acute injury.

    Science.gov (United States)

    Freedman, Benjamin R; Sarver, Joseph J; Buckley, Mark R; Voleti, Pramod B; Soslowsky, Louis J

    2014-06-27

    Achilles tendon injuries affect both athletes and the general population, and their incidence is rising. In particular, the Achilles tendon is subject to dynamic loading at or near failure loads during activity, and fatigue induced damage is likely a contributing factor to ultimate tendon failure. Unfortunately, little is known about how injured Achilles tendons respond mechanically and structurally to fatigue loading during healing. Knowledge of these properties remains critical to best evaluate tendon damage induction and the ability of the tendon to maintain mechanical properties with repeated loading. Thus, this study investigated the mechanical and structural changes in healing mouse Achilles tendons during fatigue loading. Twenty four mice received bilateral full thickness, partial width excisional injuries to their Achilles tendons (IACUC approved) and twelve tendons from six uninjured mice were used as controls. Tendons were fatigue loaded to assess mechanical and structural properties simultaneously after 0, 1, 3, and 6 weeks of healing using an integrated polarized light system. Results showed that the number of cycles to failure decreased dramatically (37-fold, ptendon structural properties, the apparent birefringence was able to best predict dynamic modulus (R(2)=0.88-0.92) throughout healing and fatigue life. This study reinforces the concept that fatigue loading is a sensitive metric to assess tendon healing and demonstrates potential structural metrics to predict mechanical properties. © 2013 Published by Elsevier Ltd.

  2. The effect of mechanical stimulation on the maturation of TDSCs-poly(L-lactide-co-e-caprolactone)/collagen scaffold constructs for tendon tissue engineering.

    Science.gov (United States)

    Xu, Yuan; Dong, Shiwu; Zhou, Qiang; Mo, Xiumei; Song, Lei; Hou, Tianyong; Wu, Jinglei; Li, Songtao; Li, Yudong; Li, Pei; Gan, Yibo; Xu, Jianzhong

    2014-03-01

    Mechanical stimulation plays an important role in the development and remodeling of tendons. Tendon-derived stem cells (TDSCs) are an attractive cell source for tendon injury and tendon tissue engineering. However, these cells have not yet been fully explored for tendon tissue engineering application, and there is also lack of understanding to the effect of mechanical stimulation on the maturation of TDSCs-scaffold construct for tendon tissue engineering. In this study, we assessed the efficacy of TDSCs in a poly(L-lactide-co-ε-caprolactone)/collagen (P(LLA-CL)/Col) scaffold under mechanical stimulation for tendon tissue engineering both in vitro and in vivo, and evaluated the utility of the transplanted TDSCs-scaffold construct to promote rabbit patellar tendon defect regeneration. TDSCs displayed good proliferation and positive expressed tendon-related extracellular matrix (ECM) genes and proteins under mechanical stimulation in vitro. After implanting into the nude mice, the fluorescence imaging indicated that TDSCs had long-term survival, and the macroscopic evaluation, histology and immunohistochemistry examinations showed high-quality neo-tendon formation under mechanical stimulation in vivo. Furthermore, the histology, immunohistochemistry, collagen content assay and biomechanical testing data indicated that dynamically cultured TDSCs-scaffold construct could significantly contributed to tendon regeneration in a rabbit patellar tendon window defect model. TDSCs have significant potential to be used as seeded cells in the development of tissue-engineered tendons, which can be successfully fabricated through seeding of TDSCs in a P(LLA-CL)/Col scaffold followed by mechanical stimulation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Specialisation of extracellular matrix for function in tendons and ligaments

    Science.gov (United States)

    Birch, Helen L.; Thorpe, Chavaunne T.; Rumian, Adam P.

    2013-01-01

    Summary 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. PMID:23885341

  4. Turkey model for flexor tendon research: in vitro comparison of human, canine, turkey, and chicken tendons.

    Science.gov (United States)

    Kadar, Assaf; Thoreson, Andrew R; Reisdorf, Ramona L; Amadio, Peter C; Moran, Steven L; Zhao, Chunfeng

    2017-08-01

    Flexor tendon injuries are one of the most common hand injuries and remain clinically challenging for functional restoration. Canine and chicken have been the most commonly used animal models for flexor tendon-related research but possess several disadvantages. The purpose of this study was to explore a potential turkey model for flexor tendon research. The third digit from human cadaveric hands, canine forepaws, turkey foot, and chicken foot were used for this study. Six digits in each of four species were studied in detail, comparing anatomy of the flexor apparatus, joint range of motioņ tendon excursion, tendon cross-sectional area, work of flexion, gliding resistance at the level of the A2 pulley, modulus of elasticity, suture retention strength, and histology across species. Anatomically, the third digit in the four species displayed structural similarities; however, the tendon cross-sectional area of the turkey and human were similar and larger than canine and chicken. Furthermore, the turkey digit resembles the human's finger with the lack of webbing between digits, similar vascularization, tendon excursion, work of flexion, gliding resistance, mechanical properties, and suture holding strength. More importantly, human and turkey tendons were most similar in histological appearance. Turkey flexor tendons have many properties that are comparable to human flexor tendons which would provide a clinically relevant, economical, nonhuman companion large animal model for flexor tendon research. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Mechanical properties of transription

    Science.gov (United States)

    Sevier, Stuart; Levine, Herbert

    Over the last several decades it has been increasingly recognized that both stochastic and mechanical processes play a central role in transcription. Though many aspects have been explained a number of fundamental properties are undeveloped. Recent results have pointed to mechanical feedback as the source of transcriptional bursting and DNA supercoiling but a reconciliation of this perspective with preexisting views of transcriptional is lacking. In this work we present a simple model of transcription where RNA elongation, RNA polymerase rotation and DNA supercoiling are coupled. The mechanical properties of each object form a foundational framework for understanding the physical nature of transcription. The resulting model can explain several important aspects of chromatin structure and generates a number of predictions for the mechanical properties of transcription.

  6. The effect of glucocorticoids on tendon cell viability in human tendon explants

    Science.gov (United States)

    Lui, Wai Ting; Chuen Fu, Sai; Man Lee, Kwong

    2009-01-01

    Background and purpose Previous studies on the culture of human tenocytes have shown that dexamethasone and triamcino-lone reduce cell viability, suppress cell proliferation, and reduce collagen synthesis. However, such cell cultures lack the extracellular matrix and three-dimensional structure of normal tendons, which affects their response to stimuli. We established a human tendon explant culture system and tested the effects of dexamethasone and triamcinolone on cell viability. Methods Primary human tendon explant cultures were prepared from healthy hamstring tendons. Tendon strips were harvested from hamstring tendons and cultured in 24-well plates in Dulbecco’s modification of Eagle’s Medium (DMEM) supplemented with 2% fetal calf serum. The tendon explants were treated with 0 μM (control), 10 μM, or 100 μM dexamethasone sodium phosphate or 0 μM (control), 10 μM, or 100 μM triamcinolone acetonide in DMEM for 96 h. Cell viability was measured by Alamar blue assay before and after glucocorticoid treatment. Results Incubation with 10 μM and 100 μM dexamethasone reduced cell viability in human tendon explants by 35% and 45%, respectively, as compared to a 6% increase in the controls (p = 0.01, mixed-effects ANOVA). Triamcinolone at 10 μM and 100 μM reduced cell viability by 33% and 36%, respectively, as compared to a 9% increase in the controls (p = 0.07, mixed-effects ANOVA). Interpretation Human tendon explant cultures can be used to study the effects of glucocorticoids on human tendon. Dexamethasone and triamcinolone suppress the cell viability of human tendon in its natural 3-dimensional environment with matrix anchorage. Human tendon explant cultures provide a species-specific model for further investigation of the effects of glucocorticoids on the metabolism of the extracellular matrix of human tendon, and on its mechanical properties. PMID:19421908

  7. Nanoparticles for tendon healing and regeneration: literature review.

    Directory of Open Access Journals (Sweden)

    Paolo Domenico Parchi

    2016-08-01

    Full Text Available 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

  8. Tendon-Sheath Mechanisms in Flexible Membrane Wing Mini-UAVs: Control and Performance

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    Tegoeh Tjahjowidodo

    2017-01-01

    Full Text Available Flexible membrane wings (FMWs are known for two inherent advantages, that is, adaptability to gusty airflow as the wings can flex according to the gust load to reduce the effective angle of attack and the ability to be folded for compact storage purposes. However, the maneuverability of UAV with FMWs is rather limited as it is impossible to install conventional ailerons. The maneuver relies only on the rudders. Some applications utilize torque rods to warp the wings, but this approach makes the FMW become unfoldable. In this research, we proposed the application of a tendon-sheath mechanism to manipulate the wing shape of UAV. Tendon-sheath mechanism is relatively flexible; thus, it can also be folded together with the wings. However, its severe nonlinearity in its dynamics makes the wing warping difficult to control. To compensate for the nonlinearity, a dedicated adaptive controller is designed and implemented. The proposed approach is validated experimentally in a wind tunnel facility with imitated gusty condition and subsequently tested in a real flight condition. The results demonstrate a stable and robust wing warping actuation, while the adaptive washout capability is also validated. Accurate wing warping is achieved and the UAV is easily controlled in a real flight test.

  9. Tissue engineering of flexor tendons: the effect of a tissue bioreactor on adipoderived stem cell-seeded and fibroblast-seeded tendon constructs.

    Science.gov (United States)

    Angelidis, Ioannis K; Thorfinn, Johan; Connolly, Ian D; Lindsey, Derek; Pham, Hung M; Chang, James

    2010-09-01

    Tissue-engineered flexor tendons could eventually be used for reconstruction of large tendon defects. The goal of this project was to examine the effect of a tissue bioreactor on the biomechanical properties of tendon constructs seeded with adipoderived stem cells (ASCs) and fibroblasts (Fs). Rabbit rear paw flexor tendons were acellularized and seeded with ASCs or Fs. A custom bioreactor applied a cyclic mechanical load of 1.25 N at 1 cycle/minute for 5 days onto the tendon constructs. Three additional groups were used as controls: fresh tendons and tendons reseeded with either ASCs or Fs that were not exposed to the bioreactor treatment and were left in stationary incubation for 5 days. We compared the ultimate tensile stress (UTS) and elastic modulus (EM) of bioreactor-treated tendons with the unloaded control tendons and fresh tendons. Comparison across groups was assessed using one-way analysis of variance with the significance level set at ptendons that were exposed to cyclic load were significantly higher than those of unloaded control tendons. Acellularized tendon constructs that were reseeded with ASCs and exposed to a cyclic load had a UTS of 66.76 MPa and an EM of 906.68 MPa; their unloaded equivalents had a UTS of 47.90 MPa and an EM of 715.57 MPa. Similar trends were found in the fibroblast-seeded tendon constructs that were exposed to the bioreactor treatment. The bioreactor-treated tendons approached the UTS and EM values of fresh tendons. Histologically, we found that cells reoriented themselves parallel to the direction of strain in response to cyclic strain. The application of cyclic strain on seeded tendon constructs that were treated with the bioreactor helped achieve a UTS and an EM comparable with those of fresh tendons. Bioreactor pretreatment and alternative cell lines, such as ASCs and Fs, might therefore contribute to the in vitro production of strong tendon material. Copyright 2010. Published by Elsevier Inc.

  10. Effects of repeated ankle stretching on calf muscle-tendon and ankle biomechanical properties in stroke survivors.

    Science.gov (United States)

    Gao, Fan; Ren, Yupeng; Roth, Elliot J; Harvey, Richard; Zhang, Li-Qun

    2011-06-01

    The objective of this study was to investigate changes in active and passive biomechanical properties of the calf muscle-tendon unit induced by controlled ankle stretching in stroke survivors. Ten stroke survivors with ankle spasticity/contracture and ten healthy control subjects received intervention of 60-min ankle stretching. Joint biomechanical properties including resistance torque, stiffness and index of hysteresis were evaluated pre- and post-intervention. Achilles tendon length was measured using ultrasonography. The force output of the triceps surae muscles was characterized via the torque-angle relationship, by stimulating the calf muscles at a controlled intensity across different ankle positions. Compared to healthy controls, the ankle position corresponding to the peak torque of the stroke survivors was shifted towards plantar flexion (Pstretching intervention, especially in dorsiflexion (P=0.013). Stretching significantly improved the force output of the impaired calf muscles in stroke survivors under matched stimulations (Pstretching (Pstretching loosened the ankle joint with increased passive joint range of motion and decreased joint stiffness. At the muscle-tendon level, repeated stretching improved calf muscle force output, which might be associated with decreased muscle fascicle stiffness, increased fascicle length and shortening of the Achilles tendon. The study provided evidence of improvement in muscle tendon properties through stretching intervention. Copyright © 2010 Elsevier Ltd. All rights reserved.

  11. Characterizing the macro and micro mechanical properties of scaffolds for rotator cuff repair.

    Science.gov (United States)

    Smith, Richard D J; Zargar, Nasim; Brown, Cameron P; Nagra, Navraj S; Dakin, Stephanie G; Snelling, Sarah J B; Hakimi, Osnat; Carr, Andrew

    2017-11-01

    Retearing after rotator cuff surgery is a major clinical problem. Numerous scaffolds are being used to try to reduce retear rates. However, few have demonstrated clinical efficacy. We hypothesize that this lack of efficacy is due to insufficient mechanical properties. Therefore, we compared the macro and nano/micro mechanical properties of 7 commercially available scaffolds to those of the human supraspinatus tendons, whose function they seek to restore. The clinically approved scaffolds tested were X-Repair, LARS ligament, Poly-Tape, BioFiber, GraftJacket, Permacol, and Conexa. Fresh frozen cadaveric human supraspinatus tendon samples were used. Macro mechanical properties were determined through tensile testing and rheometry. Scanning probe microscopy and scanning electron microscopy were performed to assess properties of materials at the nano/microscale (morphology, Young modulus, loss tangent). None of the scaffolds tested adequately approximated both the macro and micro mechanical properties of human supraspinatus tendon. Macroscale mechanical properties were insufficient to restore load-bearing function. The best-performing scaffolds on the macroscale (X-Repair, LARS ligament) had poor nano/microscale properties. Scaffolds approximating tendon properties on the nano/microscale (BioFiber, biologic scaffolds) had poor macroscale properties. Existing scaffolds failed to adequately approximate the mechanical properties of human supraspinatus tendons. Combining the macroscopic mechanical properties of a synthetic scaffold with the micro mechanical properties of biologic scaffold could better achieve this goal. Future work should focus on advancing techniques to create new scaffolds with more desirable mechanical properties. This may help improve outcomes for rotator cuff surgery patients. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  12. Radiographic analysis of factors predisposing toward tendon tears in the knee extensor mechanism

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    Rodrigo Pires e Albuquerque

    2014-08-01

    Full Text Available Objectives:To review radiographs of patients who suffered tendon tears of the knee extensor apparatus and observe alterations that might be factors predisposing toward this type of injury.Methods:We retrospectively analyzed 60 cases of injury to the knee extensor mechanism that were treated surgically at the Miguel Couto Municipal Hospital between March 2004 and March 2011. Four patients were excluded due to poor quality of the examination.Results:Of the 56 patients evaluated, 23 were considered to be normal and 33 presented radiographic alterations. Among these, eight (24.3% presented suprapatellar osteophytes alone; seven (21.2%, infrapatellar calcification; seven (21.2%, suprapatellar calcification; six (18.2%, supra- and infrapatellar osteophytes; and five (15.1%, infrapatellar osteophytes alone.Conclusion:Radiographic alterations were frequently observed in patients with extensor mechanism tears.

  13. Sex differences in tendon structure and function.

    Science.gov (United States)

    Sarver, Dylan C; Kharaz, Yalda Ashraf; Sugg, Kristoffer B; Gumucio, Jonathan P; Comerford, Eithne; Mendias, Christopher L

    2017-10-01

    Tendons play a critical role in the transmission of forces between muscles and bones, and chronic tendon injuries and diseases are among the leading causes of musculoskeletal disability. Little is known about sex-based differences in tendon structure and function. Our objective was to evaluate the mechanical properties, biochemical composition, transcriptome, and cellular activity of plantarflexor tendons from 4 month old male and female C57BL/6 mice using in vitro biomechanics, mass spectrometry-based proteomics, genome-wide expression profiling, and cell culture techniques. While the Achilles tendons of male mice were approximately 6% larger than female mice (p differences in mechanical properties (p > 0.05) of plantaris tendons were observed. Mass spectrometry proteomics analysis revealed no significant difference between sexes in the abundance of major extracellular matrix (ECM) proteins such as collagen types I (p = 0.30) and III (p = 0.68), but female mice had approximately twofold elevations (p differed by only 1%. In vitro, neither the sex of the serum that fibroblasts were cultured in, nor the sex of the ECM in which they were embedded, had profound effects on the expression of collagen and cell proliferation genes. Our results indicate that while male mice expectedly had larger tendons, male and female tendons have very similar mechanical properties and biochemical composition, with small increases in some ECM proteins and proteoglycans evident in female tendons. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2117-2126, 2017. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  14. Shear Wave Measurements for Evaluation of Tendon Diseases.

    Science.gov (United States)

    Yeh, Chia-Lun; Kuo, Po-Ling; Gennisson, Jean-Luc; Brum, Javier; Tanter, Mickael; Li, Pai-Chi

    2016-11-01

    This paper investigated the feasibility of using supersonic shear wave measurements to quantitatively differentiate normal and damaged tendons based on their mechanical properties. Five freshly harvested porcine tendons excised from pig legs were used. Tendon damage was induced by incubating the tendons with a 1% w/v collagenase solution. Values of shear modulus were derived both by a time-of-flight (TOF) approach and a transverse isotropic plate model (TI-model). The results show that as the preload applied to the tendon increased from 0 to 3 N, the mean shear modulus derived based on the TOF approach, the TI-model, and Young's modulus estimated from mechanical testing increased from 14.6 to 89.9 kPa, 53.9 to 348 kPa, and from 1.45 to 10.36 MPa, respectively, in untreated tendons, and from 8.4 to 67 kPa, 28 to 258 kPa, and from 0.93 to 7.2 MPa in collagenase-treated tendons. Both the TOF approach and the TI-model correlated well with the changes in Young's modulus. Although there is bias on the estimation of shear modulus using the TOF approach, it still provides statistical significance to differentiate normal and damaged tendons. Our data indicate that supersonic shear wave imaging is a valuable imaging technique to assess tendon stiffness dynamics and characterize normal and collagenase-damaged tendons.

  15. Increased unilateral tendon stiffness and its effect on gait 2-6 years after Achilles tendon rupture.

    Science.gov (United States)

    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. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  16. Achilles tendon stress is more sensitive to subject-specific geometry than subject-specific material properties: A finite element analysis.

    Science.gov (United States)

    Hansen, Wencke; Shim, Vickie B; Obst, Steven; Lloyd, David G; Newsham-West, Richard; Barrett, Rod S

    2017-05-03

    This study used subject-specific measures of three-dimensional (3D) free Achilles tendon geometry in conjunction with a finite element method to investigate the effect of variation in subject-specific geometry and subject-specific material properties on tendon stress during submaximal isometric loading. Achilles tendons of eight participants (Aged 25-35years) were scanned with freehand 3D ultrasound at rest and during a 70% maximum voluntary isometric contraction. Ultrasound images were segmented, volume rendered and transformed into subject-specific 3D finite element meshes. The mean (±SD) lengths, volumes and cross-sectional areas of the tendons at rest were 62±13mm, 3617±984mm3 and 58±11mm2 respectively. The measured tendon strain at 70% MVIC was 5.9±1.3%. Subject-specific material properties were obtained using an optimisation approach that minimised the difference between measured and modelled longitudinal free tendon strain. Generic geometry was represented by the average mesh and generic material properties were taken from the literature. Local stresses were subsequently computed for combinations of subject-specific and generic geometry and material properties. For a given geometry, changing from generic to subject-specific material properties had little effect on the stress distribution in the tendon. In contrast, changing from generic to subject-specific geometry had a 26-fold greater effect on tendon stress distribution. Overall, these findings indicate that the stress distribution experienced by the living free Achilles tendon of a young and healthy population during voluntary loading are more sensitive to variation in tendon geometry than variation in tendon material properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Extensor mechanism of the knee: MR imaging of tendon injuries; Sistema extensor do joelho: ressonancia magnetica das lesoes tendinosas

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    Torriani, Martin; Maeda, Lucimara; Cerqueira, Elza M.F.P.; Montandon, Cristiano; Zanardi, Veronica A. [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Ciencias Medicas. Dept. de Radiologia

    2000-04-01

    The authors describe the normal MR imaging appearance of the extensor tendons of the knee and the lesions that may affect these structures. MR imaging was performed in patients presenting with a variety of injuries of the extensor mechanism of the knee. MR imaging is the method of choice to evaluate tendon injuries, due to its high anatomic resolution. The knowledge of the normal anatomy and the recognition of the spectrum of the injuries that involve these structures are important for an early diagnosis and appropriate management of these patients. (author)

  18. FIBRILLINS IN TENDON

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    Betti Giusti

    2016-10-01

    Full Text Available Tendons among connective tissue, mainly collagen, contain also elastic fibres 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 elastic fibres in tendons have been performed. Aim of this review is to revise data on the organization of elastic fibres in tendons, in particular fibrillin structure and function, and on the clinical manifestations associated to alterations of elastic fibres 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 and Beals syndrome. The two diseases are caused by mutations in genes FBN1 and FBN2 encoding fibrillin 1 and fibrillin 2, respectively.

  19. Mechanical properties of wood

    Science.gov (United States)

    David W. Green; Jerrold E. Winandy; David E. Kretschmann

    1999-01-01

    The mechanical properties presented in this chapter were obtained from tests of small pieces of wood termed “clear” and “straight grained” because they did not contain characteristics such as knots, cross grain, checks, and splits. These test pieces did have anatomical characteristics such as growth rings that occurred in consistent patterns within each piece. Clear...

  20. Influence of mechanical unloading on histological changes of the patellar tendon insertion in rabbits.

    Science.gov (United States)

    Mutsuzaki, Hirotaka; Nakajima, Hiromi; Wadano, Yasuyoshi; Takahashi, Hikaru; Sakane, Masataka

    2015-12-01

    The purpose of this study was to clarify the influence of mechanical unloading on histological changes of the patellar tendon (PT) insertion in rabbits. The PT was completely released from stress by drawing the patella toward the tibial tubercle with a stainless steel wire installed between the patella and tibial tubercle (mechanical unloading group, n=28). The animals of the sham group underwent the same surgical procedure; however, the wire was not tightened (n=28). The average thickness of the Safranin O-stained glycosaminoglycan (GAG) area, chondrocyte apoptosis rate and chondrocyte proliferation rate of the cartilage layer at the insertion were measured at one, two, four, and six weeks. The chondrocyte apoptosis rate in the mechanical unloading group was significantly higher than that in the sham group at one and four weeks (pmechanical unloading group was significantly lower than that in the sham group at four and six weeks (pmechanical unloading group was significantly lower than that in the sham group at six weeks (pMechanical unloading significantly affected the increase in the chondrocyte apoptosis rate, decrease in the chondrocyte proliferation rate, and decrease in the GAG layer thickness at the PT insertion for up to six weeks in rabbits. We suggest that more than 6 weeks of mechanical unloading should be avoided to prevent degeneration at the PT insertion. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Mechanical Properties of Transcription.

    Science.gov (United States)

    Sevier, Stuart A; Levine, Herbert

    2017-06-30

    The mechanical properties of transcription have recently been shown to play a central role in gene expression. However, a full physical characterization of this central biological process is lacking. In this Letter, we introduce a simple description of the basic physical elements of transcription where RNA elongation, RNA polymerase rotation, and DNA supercoiling are coupled. The resulting framework describes the relative amount of RNA polymerase rotation and DNA supercoiling that occurs during RNA elongation. Asymptotic behavior is derived and can be used to experimentally extract unknown mechanical parameters of transcription. Mechanical limits to transcription are incorporated through the addition of a DNA supercoiling-dependent RNA polymerase velocity. This addition can lead to transcriptional stalling and resulting implications for gene expression, chromatin structure and genome organization are discussed.

  2. Engineering Tendon: Scaffolds, Bioreactors, and Models of Regeneration.

    Science.gov (United States)

    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.

  3. Engineering Tendon: Scaffolds, Bioreactors, and Models of Regeneration

    Directory of Open Access Journals (Sweden)

    Daniel W. Youngstrom

    2016-01-01

    Full Text Available 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.

  4. Effect of exercise-induced enhancement of the leg-extensor muscle-tendon unit capacities on ambulatory mechanics and knee osteoarthritis markers in the elderly.

    Science.gov (United States)

    Karamanidis, Kiros; Oberländer, Kai Daniel; Niehoff, Anja; Epro, Gaspar; Brüggemann, Gert-Peter

    2014-01-01

    Leg-extensor muscle weakness could be a key component in knee joint degeneration in the elderly because it may result in altered muscular control during locomotion influencing the mechanical environment within the joint. This work aimed to examine whether an exercise-induced enhancement of the triceps surae (TS) and quadriceps femoris (QF) muscle-tendon unit (MTU) capacities would affect mechanical and biological markers for knee osteoarthritis in the elderly. Twelve older women completed a 14-week TS and QF MTU exercise intervention, which had already been established as increasing muscle strength and tendon stiffness. Locomotion mechanics and serum cartilage oligomeric matrix protein (COMP) levels were examined during incline walking. MTU mechanical properties were assessed using simultaneously ultrasonography and dynamometry. Post exercise intervention, the elderly had higher TS and QF contractile strength and tendon-aponeurosis stiffness. Regarding the incline gait task, the subjects demonstrated a lower external knee adduction moment and lower knee adduction angular impulse during the stance phase post-intervention. Furthermore, post-intervention compared to pre-intervention, the elderly showed lower external hip adduction moment, but revealed higher plantarflexion pushoff moment. The changes in the external knee adduction moment were significantly correlated with the improvement in ankle pushoff function. Serum COMP concentration increased in response to the 0.5-h incline walking exercise with no differences in the magnitude of increment between pre- and post-intervention. This work emphasizes the important role played by the ankle pushoff function in knee joint mechanical loading during locomotion, and may justify the inclusion of the TS MTU in prevention programs aiming to positively influence specific mechanical markers for knee osteoarthritis in the elderly. However, the study was unable to show that COMP is amenable to change in the elderly following a

  5. The mechanical interaction between three geometric types of nylon core suture and a running epitenon suture in repair of porcine flexor tendons

    NARCIS (Netherlands)

    Wit, T.; Walbeehm, E.T.; Hovius, S.E.; McGrouther, D.A.

    2013-01-01

    The effect of core suture geometry on the mechanical interaction with the epitenon suture in terms of gap prevention, failure strength and mode of failure was investigated in a flexor tendon repair model. A total of 48 porcine flexor tendons were repaired using three techniques with distinct core

  6. Mechanical Properties of Cells

    Science.gov (United States)

    Bradley, Robert; Becerril, Joseph; Jeevarajan, Anthony

    2007-01-01

    Many physiologic and pathologic processes alter the biomechanical properties of the tissue they affect, and these changes may be manifest at the single cell level. The normal and abnormal mechanical properties of a given cell type can be established with the aid of an atomic force microscope (AFM), nonetheless, consistency in the area of the tip has been a mayor limitation of using the AFM for quantitative measurements of mechanical properties. This project attempts to overcome this limitation by using materials with a known elastic modulus, which resembles the one of the cell, to create force-deformation curves to calculate the area of indentation by means of Hooke s Law (sigma = E(epsilon)), which states that stress (sigma) is proportional to the strain (epsilon) where the constant of proportionality, E, is called the Young s modulus, also referred as the elastic modulus. Hook s Law can be rearranged to find the area of indentation (Area= Force/ E(epsilon)), where the indentation force is defined by the means of the added mass spring calibration method.

  7. Achilles Tendonitis

    Science.gov (United States)

    ... You Treat Achilles Tendonitis? en español Tendinitis de Aquiles Kim didn't do much over the summer ... Achilles Tendonitis and Who Gets It? Your Achilles tendon is located at the back of your foot, ...

  8. Evaluation of Elastic Stiffness in Healing Achilles Tendon After Surgical Repair of a Tendon Rupture Using In Vivo Ultrasound Shear Wave Elastography.

    Science.gov (United States)

    Zhang, Li-ning; Wan, Wen-bo; Wang, Yue-xiang; Jiao, Zi-yu; Zhang, Li-hai; Luo, Yu-kun; Tang, Pei-fu

    2016-04-09

    BACKGROUND There has been no published report assessing the mechanical properties of a repaired Achilles tendon after surgery using shear wave elastography (SWE). The aim of this study was to investigate the changes in mechanical properties of the healing Achilles tendon after surgical repair of a tendon rupture using ultrasound SWE and how these changes correlate with tendon function. MATERIAL AND METHODS Twenty-six patients who underwent surgical repair for Achilles tendon rupture were examined with ultrasound SWE coupled with a linear array transducer (4-15 MHz). The elasticity values of the repaired Achilles tendon in a longitudinal view were measured at 12, 24, and 48 weeks postoperatively. Functional outcomes were assessed with the American Orthopedic Foot and Ankle Society (AOFAS) rating system at 12, 24, and 48 weeks postoperatively. General linear regression analysis and correlation coefficients were used to analyze the relationship between elasticity and the AOFAS score. RESULTS There were significant differences with respect to the mean elasticity values and functional scores of the repaired Achilles tendon at 12, 24, and 48 weeks postoperatively (all PTendon function was positively correlated with the elasticity of the repaired Achilles tendon (P=0.0003). CONCLUSIONS Our findings suggest that SWE can provide biomechanical information for evaluating the mechanical properties of healing Achilles tendon and predict Achilles tendon function.

  9. Primary gene response to mechanical loading in healing rat Achilles tendons

    DEFF Research Database (Denmark)

    Eliasson, Pernilla; Andersson, Therese; Hammerman, Malin

    2013-01-01

    Loading can stimulate tendon healing. In healing rat Achilles tendons, we have found more than 150 genes upregulated or downregulated 3 h after one loading episode. We hypothesized that these changes were preceded by a smaller number of regulatory genes and thus performed a microarray 15 min afte...

  10. Effects of gamma irradiation on the biomechanical properties of peroneus tendons

    Directory of Open Access Journals (Sweden)

    Aguila CM

    2016-09-01

    Full Text Available Christopher M Aguila,1 Gaëtan J-R Delcroix,2–5 David N Kaimrajh,6 Edward L Milne,6 H Thomas Temple,5,7 Loren L Latta2,6 1Department of Biological Sciences, Florida International University, Miami, FL, USA; 2Department of Orthopaedics, Miller School of Medicine, University of Miami, Miami, FL, USA; 3Research Service & Geriatric Research, Education, and Clinical Center, Bruce W. Carter Veterans Affairs Medical Center, Miami, FL, USA; 4Interdisciplinary Stem Cell Institute, University of Miami, Miami, FL, USA; 5Vivex Biomedical Inc., Marietta, GA, USA; 6Max Biedermann Institute for Biomechanics, Miami Beach, FL, USA; 7Translational Research and Economic Development, Nova Southeastern University, Fort-Lauderdale, FL, USA Purpose: This study was designed to investigate the biomechanical properties of nonirradiated (NI and irradiated (IR peroneus tendons to determine if they would be suitable allografts, in regards to biomechanical properties, for anterior cruciate ligament reconstruction after a dose of 1.5–2.5 Mrad.Methods: Seven pairs of peroneus longus (PL and ten pairs of peroneus brevis (PB tendons were procured from human cadavers. The diameter of each allograft was measured. The left side of each allograft was IR at 1.5–2.5 Mrad, whereas the right side was kept aseptic and NI. The allografts were thawed, kept wet with saline, and attached in a single-strand fashion to custom freeze grips using liquid nitrogen. A preload of 10 N was then applied and, after it had reached steady state, the allografts were pulled at 4 cm/sec. The parameters recorded were the displacement and force.Results: The elongation at the peak load was 10.3±2.3 mm for the PB NI side and 13.5±3.3 mm for the PB IR side. The elongation at the peak load was 17.4±5.3 mm for the PL NI side and 16.3±2.0 mm for the PL IR side. For PL, the ultimate load was 2,091.6±148.7 N for NI and 2,122.8±380.0 N for IR. The ultimate load for the PB tendons was 1,485.7±209.3 N for

  11. Experimental flexor tendon healing without adhesion formation--a new concept of tendon nutrition and intrinsic healing mechanisms. A preliminary report.

    Science.gov (United States)

    Lundborg, G

    1976-10-01

    An experimental model is presented enabling an analysis of the healing process of completely cut and re-sutured free segments of rabbit flexor tendons, kept avascular in a synovial milieu and completely isolated from adhesion formation. Under these conditions the cut tendons heal within a few weeks. It can be shown that this healing process is a result of intrinsic tendon cell activity only.

  12. The adaptability of tendon to loading differs in men and women

    DEFF Research Database (Denmark)

    Magnusson, S Peter; Hansen, Mette; Langberg, Henning

    2007-01-01

    The reason why women sustain more soft tissue injury than men during physical activity is unknown. Connective tissue properties and extracellular matrix adaptability in human tendon were investigated in models that addressed biochemical, physiological and biomechanical aspects of tendon connective...... tissue in response to mechanical loading. Habitual training resulted in a larger patellar tendon in men but not in women. Following an acute bout of exercise, men had an elevated tendon collagen synthesis rate and this effect was less pronounced or absent in women. Moreover, levels of circulating...... oestrogen affected the acute exercise-related increase in collagen synthesis. Finally, the mechanical strength of isolated tendon collagen fascicles in men surpassed that of women. Thus, compared to men, women have (i) an attenuated tendon hypertrophy response to habitual training; (ii) a lower tendon...

  13. Is the Dresden technique a mechanical design of choice suitable for the repair of middle third Achilles tendon ruptures? A biomechanical study.

    Science.gov (United States)

    de la Fuente, C; Carreño-Zillmann, G; Marambio, H; Henríquez, H

    2016-01-01

    To compare the mechanical failure of the Dresden technique for Achilles tendon repair with the double modified Kessler technique controlled repair technique. The maximum resistance of the two repair techniques are also compared. A total of 30 Achilles tendon ruptures in bovine specimens were repaired with an Ethibond(®) suture to 4.5cm from the calcaneal insertion. Each rupture was randomly distributed into one of two surgical groups. After repair, each specimen was subjected to a maximum traction test. The mechanical failure (tendon, suture, or knot) rates (proportions) were compared using the exact Fisher test (α=.05), and the maximum resistances using the Student t test (α=.05). There was a difference in the proportions of mechanical failures, with the most frequent being a tendon tear in the Dresden technique, and a rupture of the suture in the Kessler technique. The repair using the Dresden technique performed in the open mode, compared to the Kessler technique, has a more suitable mechanical design for the repair of middle third Achilles tendon ruptures on developing a higher tensile resistance in 58.7%. However, its most common mechanical failure was a tendon tear, which due to inappropriate loads could lead to lengthening of the Achilles tendon. Copyright © 2016 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

  14. Effects of Contract-Relax, Static Stretching, and Isometric Contractions on Muscle-Tendon Mechanics.

    Science.gov (United States)

    Kay, Anthony D; Husbands-Beasley, Jade; Blazevich, Anthony J

    2015-10-01

    Loading characteristics of stretching techniques likely influence the specific mechanisms responsible for acute increases in range of motion (ROM). Therefore, the effects of a version of contract-relax (CR) proprioceptive neuromuscular facilitation stretching, static stretching (SS), and maximal isometric contraction (Iso) interventions were studied in 17 healthy human volunteers. Passive ankle moment was recorded on an isokinetic dynamometer, with EMG recording from the triceps surae, simultaneous real-time motion analysis, and ultrasound-imaging-recorded gastrocnemius medialis muscle and Achilles tendon elongation. Subjects then performed each intervention randomly on separate days before reassessment. Significant increases in dorsiflexion ROM (2.5°-5.3°; P stretching (P stretching and Iso (17.7%-22.1%; P 0.05), whereas significant reductions in muscle stiffness occurred after CR stretching and SS (16.0%-20.5%; P 0.05). Increases in peak passive moment (stretch tolerance) occurred after Iso (6.8%; P stretching (10.6%; P = 0.08), and SS (5.2%; P = 0.08); no difference in changes between conditions was found (P > 0.05). Significant correlations (rs = 0.69-0.82; P stretching suggest a broader adaptive response that likely explains its superior efficacy in acutely increasing ROM. Although mechanical changes appear tissue-specific between interventions, similar increases in stretch tolerance after all interventions are strongly correlated with changes in ROM.

  15. Exploratory factor analysis for differentiating sensory and mechanical variables related to muscle-tendon unit elongation

    Directory of Open Access Journals (Sweden)

    Mauro H. Chagas

    2016-01-01

    Full Text Available ABSTRACT Background Stretching exercises are able to promote adaptations in the muscle-tendon unit (MTU, which can be tested through physiological and biomechanical variables. Identifying the key variables in MTU adaptations is crucial to improvements in training. Objective To perform an exploratory factor analysis (EFA involving the variables often used to evaluate the response of the MTU to stretching exercises. Method Maximum joint range of motion (ROMMAX, ROM at first sensation of stretching (FSTROM, peak torque (torqueMAX, passive stiffness, normalized stiffness, passive energy, and normalized energy were investigated in 36 participants during passive knee extension on an isokinetic dynamometer. Stiffness and energy values were normalized by the muscle cross-sectional area and their passive mode assured by monitoring the EMG activity. Results EFA revealed two major factors that explained 89.68% of the total variance: 53.13% was explained by the variables torqueMAX, passive stiffness, normalized stiffness, passive energy, and normalized energy, whereas the remaining 36.55% was explained by the variables ROMMAX and FSTROM. Conclusion This result supports the literature wherein two main hypotheses (mechanical and sensory theories have been suggested to describe the adaptations of the MTU to stretching exercises. Contrary to some studies, in the present investigation torqueMAX was significantly correlated with the variables of the mechanical theory rather than those of the sensory theory. Therefore, a new approach was proposed to explain the behavior of the torqueMAX during stretching exercises.

  16. Tendon functional extracellular matrix.

    Science.gov (United States)

    Screen, Hazel R C; Berk, David E; Kadler, Karl E; Ramirez, Francesco; Young, Marian F

    2015-06-01

    This article is one of a series, summarizing views expressed at the Orthopaedic Research Society New Frontiers in Tendon Research Conference. This particular article reviews the three workshops held under the "Functional Extracellular Matrix" stream. The workshops focused on the roles of the tendon extracellular matrix, such as performing the mechanical functions of tendon, creating the local cell environment, and providing cellular cues. Tendon is a complex network of matrix and cells, and its biological functions are influenced by widely varying extrinsic and intrinsic factors such as age, nutrition, exercise levels, and biomechanics. Consequently, tendon adapts dynamically during development, aging, and injury. The workshop discussions identified research directions associated with understanding cell-matrix interactions to be of prime importance for developing novel strategies to target tendon healing or repair. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  17. The effect of decellularized matrices on human tendon stem/progenitor cell differentiation and tendon repair.

    Science.gov (United States)

    Yin, Zi; Chen, Xiao; Zhu, Ting; Hu, Jia-jie; Song, Hai-xin; Shen, Wei-liang; Jiang, Liu-yun; Heng, Boon Chin; Ji, Jun-feng; Ouyang, Hong-Wei

    2013-12-01

    It is reported that decellularized collagen matrices derived from dermal skin and bone have been clinically used for tendon repair. However, the varying biological and physical properties of matrices originating from different tissues may influence the differentiation of tendon stem cells, which has not been systematically evaluated. In this study, the effects of collagenous matrices derived from different tissues (tendon, bone and dermis) on the cell differentiation of human tendon stem/progenitor cells (hTSPCs) were investigated, in the context of tendon repair. It was found that all three matrices supported the adhesion and proliferation of hTSPCs despite differences in topography. Interestingly, tendon-derived decellularized matrix promoted the tendinous phenotype in hTSPCs and inhibited their osteogenesis, even under osteogenic induction conditions, through modulation of the teno- and osteolineage-specific transcription factors Scleraxis and Runx2. Bone-derived decellularized matrix robustly induced osteogenic differentiation of hTSPCs, whereas dermal skin-derived collagen matrix had no apparent effect on hTSPC differentiation. Based on the specific biological function of the tendon-derived decellularized matrix, a tissue-engineered tendon comprising TSPCs and tendon-derived matrix was successfully fabricated for Achilles tendon reconstruction. Implantation of this cell-scaffold construct led to a more mature structure (histology score: 4.08 ± 0.61 vs. 8.51 ± 1.66), larger collagen fibrils (52.2 ± 1.6 nm vs. 47.5 ± 2.8 nm) and stronger mechanical properties (stiffness: 21.68 ± 7.1 Nm m(-1) vs.13.2 ± 5.9 Nm m(-1)) of repaired tendons compared to the control group. The results suggest that stem cells promote the rate of repair of Achilles tendon in the presence of a tendinous matrix. This study thus highlights the potential of decellularized matrix for future tissue engineering applications, as well as developing a practical strategy for functional tendon

  18. Are Sport-Specific Profiles of Tendon Stiffness and Cross-Sectional Area Determined by Structural or Functional Integrity?

    Directory of Open Access Journals (Sweden)

    Hans-Peter Wiesinger

    Full Text Available The present study aimed to determine whether distinct sets of tendon properties are seen in athletes engaged in sports with contrasting requirements for tendon function and structural integrity. Patellar and Achilles tendon morphology and force-deformation relation were measured by combining ultrasonography, electromyography and dynamometry in elite ski jumpers, distance runners, water polo players and sedentary individuals. Tendon cross-sectional area normalized to body mass2/3 was smaller in water polo players than in other athletes (patellar and Achilles tendon; -28 to -24% or controls (patellar tendon only; -9%. In contrast, the normalized cross-sectional area was larger in runners (patellar tendon only; +26% and ski jumpers (patellar and Achilles tendon; +21% and +13%, respectively than in controls. Tendon stiffness normalized to body mass2/3 only differed in ski jumpers, compared to controls (patellar and Achilles tendon; +11% and +27%, respectively and to water polo players (Achilles tendon only; +23%. Tendon size appears as an adjusting variable to changes in loading volume and/or intensity, possibly to preserve ultimate strength or fatigue resistance. However, uncoupled morphological and mechanical properties indicate that functional requirements may also influence tendon adaptations.

  19. Effects of short duration static stretching on jump performance, maximum voluntary contraction, and various mechanical and morphological parameters of the muscle-tendon unit of the lower extremities.

    Science.gov (United States)

    Stafilidis, Savvas; Tilp, Markus

    2015-03-01

    Static stretching is used in sport practice but it has been associated with decrements in force and performance. Therefore, we examined the effect of short duration static stretch on the mechano-morphological properties of the m. vastus lateralis (VL) muscle tendon unit (MTU) and on the jumping performance. Eight males and three females (mean ± SD, 25.5 ± 3.1 years) stretched their lower legs for a 15 or 60 s duration or acted as their own control without stretching in a randomized order. In a pre-post design, a passive movement (5°/s) and a maximum voluntary knee extension contraction (MVC) were performed on dynamometer while the VL tendon and aponeurosis was observed via ultrasound. Furthermore, the participants performed countermovement (CMJ) and squat jumps (SJ). Repeated measures ANOVA did not show significant differences in MVC, active and passive strain, stiffness, elongation, knee joint angle range, and jump performance between and within groups. The applied stretch stimuli (15 or 60 s) were not sufficient to trigger adaptations in the mechano-morphological properties of the lower extremities MTU which therefore did neither affect jump performance nor MVC. As a possible mechanism, we hypothesized that the dose-time dependency effect of static stretch might have important implications when measuring functional parameters of the MTU and performance. Further examination is necessary to elucidate its impact in the examination of the MTU mechano-morphological properties.

  20. Dose- and time-dependent effects of genipin crosslinking on cell viability and tissue mechanics - toward clinical application for tendon repair.

    Science.gov (United States)

    Fessel, Gion; Cadby, Jennifer; Wunderli, Stefania; van Weeren, René; Snedeker, Jess G

    2014-05-01

    The crosslinking agent genipin is increasingly invoked for the mechanical augmentation of collagen tissues and implants, and has previously been demonstrated to arrest mechanical damage accumulation in various tissues. This study established an in vitro dose-response baseline for the effects of genipin treatment on tendon cells and their matrix, with a view to in vivo application to the repair of partial tendon tears. Regression models based on a broad range of experimental data were used to delineate the range of concentrations that are likely to achieve functionally effective crosslinking, and predict the corresponding degree of cell loss and diminished metabolic activity that can be expected. On these data, it was concluded that rapid mechanical augmentation of tissue properties can only be achieved by accepting some degree of cytotoxicity, yet that post-treatment cell survival may be adequate to eventually repopulate and stabilize the tissue. On this basis, development of delivery strategies and subsequent in vivo study seems warranted. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. Does aerobic exercise training promote changes in structural and biomechanical properties of the tendons in experimental animals? A systematic review.

    Science.gov (United States)

    Bezerra, M A; Lemos, A; Lira, K D S; Silveira, P V C; Coutinho, M P G; E Moraes, S R A

    2012-12-01

    To develop a systematic review to evaluate, through the best scientific evidence available, the effectiveness of aerobic exercise in improving the biomechanical characteristics of tendons in experimental animals. Two independent assessors conducted a systematic search in the databases Medline/PUBMED and Lilacs/BIREME, using the following descriptors of Mesh in animal models. The ultimate load of traction and the elastic modulus tendon were used as primary outcomes and transverse section area, ultimate stress and tendon strain as secondary outcomes. The assessment of risk of bias in the studies was carried out using the following methodological components: light/dark cycle, temperature, nutrition, housing, research undertaken in conjunction with an ethics committee, randomization, adaptation of the animals to the training and preparation for the mechanical test. Eight studies, comprising 384 animals, were selected; it was not possible to combine them into one meta-analysis due to the heterogeneity of the samples. There was a trend to increasing ultimate load without changes in the other outcomes studied. Only one study met more than 80% of the quality criteria. Physical training performed in a structured way with imposition of overloads seems to be able to promote changes in tendon structure of experimental models by increasing the ultimate load supported. However, the results of the influence of exercise on the elastic modulus parameters, strain, transverse section area and ultimate stress, remain controversial and inconclusive. Such a conclusion must be evaluated with reservation as there was low methodological control in the studies included in this review.

  2. Effects of plasma rich in growth factors (PRGF) on biomechanical properties of Achilles tendon repair.

    Science.gov (United States)

    López-Nájera, Diego; Rubio-Zaragoza, Mónica; Sopena-Juncosa, Joaquín J; Alentorn-Geli, Eduard; Cugat-Bertomeu, Ramón; Fernández-Sarmiento, J Andrés; Domínguez-Pérez, Juan M; García-Balletbó, Montserrat; Primo-Capella, Víctor J; Carrillo-Poveda, José M

    2016-12-01

    To assess the biomechanical effects of intra-tendinous injections of PRGF on the healing Achilles tendon after repair in a sheep model. Thirty sheep were randomly assigned into one of the six groups depending on the type of treatment received (PRGF or placebo) and survival time (2, 4 and 8 weeks). The Achilles tendon injury was repaired by suturing the tendinous edges employing a three-loop pulley pattern. A trans-articular external fixation system was then used for immobilization. The PRGF or placebo was administered on a weekly basis completing a maximum of three infiltrations. The force, section and tension values were compared between the operated and healthy Achilles tendons across all groups. The PRGF-treated tendons had higher force at 8 weeks compared with the placebo group (p = 0.007). Between 2 and 4 weeks, a significant increase in force in both the PRGF-treated tendon (p = 0.0027) and placebo group (p = 0.0095) occurred. No significant differences were found for section ratio between PRGF-treated tendons and the placebo group for any of the time periods evaluated. At 2 weeks, PRGF-treated tendons had higher tension ratio compared with placebo group tendons (p = 0.0143). Both PRGF and placebo treatments significantly improved the force (p Achilles tendon repair strength at 8 weeks compared with the use of placebo. The use of PRGF does not modify section and tension ratios compared with placebo at 8 weeks. The tension ratio progressively increases between 2 and 8 weeks compared with the placebo.

  3. Therapeutic Mechanisms of Human Adipose-Derived Mesenchymal Stem Cells in a Rat Tendon Injury Model.

    Science.gov (United States)

    Lee, Sang Yoon; Kwon, Bomi; Lee, Kyoungbun; Son, Young Hoon; Chung, Sun G

    2017-05-01

    Although survival of transplanted stem cells in vivo and differentiation of stem cells into tenocytes in vitro have been reported, there have been no in vivo studies demonstrating that mesenchymal stem cells (MSCs) could secrete their own proteins as differentiated tenogenic cells. Purpose/Hypothesis: Using a xenogeneic MSC transplantation model, we aimed to investigate whether MSCs could differentiate into the tenogenic lineage and secrete their own proteins. The hypothesis was that human MSCs would differentiate into the human tenogenic lineage and the cells would be able to secrete human-specific proteins in a rat tendon injury model. Controlled laboratory study. The Achilles tendons of 57 Sprague Dawley rats received full-thickness rectangular defects. After the modeling, the defective tendons were randomly assigned to 3 groups: (1) cell group, implantation with human adipose-derived mesenchymal stem cells (hASCs) and fibrin glue (106 cells in 60 μL); (2) fibrin group, implantation with fibrin glue and same volume of cell media; and (3) sham group, identical surgical procedure without any treatment. Gross observation and biomechanical, histopathological, immunohistochemistry, and Western blot analyses were performed at 2 and 4 weeks after modeling. hASCs implanted into the defective rat tendons were viable for 4 weeks as detected by immunofluorescence staining. Tendons treated with hASCs showed better gross morphological and biomechanical recovery than those in the fibrin and sham groups. Furthermore, the expression of both human-specific collagen type I and tenascin-C was significantly higher in the cell group than in the other 2 groups. Transplantation of hASCs enhanced rat tendon healing biomechanically. hASCs implanted into the rat tendon defect model survived for at least 4 weeks and secreted human-specific collagen type I and tenascin-C. These findings suggest that transplanted MSCs may be able to differentiate into the tenogenic lineage and contribute

  4. Influence of acetaminophen and ibuprofen on in vivo patellar tendon adaptations to knee extensor resistance exercise in older adults

    DEFF Research Database (Denmark)

    Carroll, C C; Dickinson, J M; LeMoine, J K

    2011-01-01

    adults induces modest changes in the mechanical properties of the patellar tendon. Over-the-counter doses of acetaminophen, but not ibuprofen, have a strong influence on tendon mechanical and material property adaptations to resistance training. These findings add to a growing body of evidence...

  5. Mechanical properties of ceramics

    CERN Document Server

    Pelleg, Joshua

    2014-01-01

    This book discusses the mechanical properties of ceramics and aims to provide both a solid background for undergraduate students, as well as serving as a text to bring practicing engineers up to date with the latest developments in this topic so they can use and apply these to their actual engineering work.  Generally, ceramics are made by moistening a mixture of clays, casting it into desired shapes and then firing it to a high temperature, a process known as 'vitrification'. The relatively late development of metallurgy was contingent on the availability of ceramics and the know-how to mold them into the appropriate forms. Because of the characteristics of ceramics, they offer great advantages over metals in specific applications in which hardness, wear resistance and chemical stability at high temperatures are essential. Clearly, modern ceramics manufacturing has come a long way from the early clay-processing fabrication method, and the last two decades have seen the development of sophisticated technique...

  6. Obesity/Type II diabetes alters macrophage polarization resulting in a fibrotic tendon healing response.

    Science.gov (United States)

    Ackerman, Jessica E; Geary, Michael B; Orner, Caitlin A; Bawany, Fatima; Loiselle, Alayna E

    2017-01-01

    Type II Diabetes (T2DM) dramatically impairs the tendon healing response, resulting in decreased collagen organization and mechanics relative to non-diabetic tendons. Despite this burden, there remains a paucity of information regarding the mechanisms that govern impaired healing of diabetic tendons. Mice were placed on either a high fat diet (T2DM) or low fat diet (lean) and underwent flexor tendon transection and repair surgery. Healing was assessed via mechanical testing, histology and changes in gene expression associated with collagen synthesis, matrix remodeling, and macrophage polarization. Obese/diabetic tendons healed with increased scar formation and impaired mechanical properties. Consistent with this, prolonged and excess expression of extracellular matrix (ECM) components were observed in obese/T2DM tendons. Macrophages are involved in both inflammatory and matrix deposition processes during healing. Obese/T2DM tendons healed with increased expression of markers of pro-inflammatory M1 macrophages, and elevated and prolonged expression of M2 macrophages markers that are involved in ECM deposition. Here we demonstrate that tendons from obese/diabetic mice heal with increased scar formation and increased M2 polarization, identifying excess M2 macrophage activity and matrix synthesis as a potential mechanism of the fibrotic healing phenotype observed in T2DM tendons, and as such a potential target to improve tendon healing in T2DM.

  7. Athletic training affects the uniformity of muscle and tendon adaptation during adolescence.

    Science.gov (United States)

    Mersmann, Falk; Bohm, Sebastian; Schroll, Arno; Marzilger, Robert; Arampatzis, Adamantios

    2016-10-01

    With the double stimulus of mechanical loading and maturation acting on the muscle-tendon unit, adolescent athletes might be at increased risk of developing imbalances of muscle strength and tendon mechanical properties. This longitudinal study aims to provide detailed information on how athletic training affects the time course of muscle-tendon adaptation during adolescence. In 12 adolescent elite athletes (A) and 8 similar-aged controls (C), knee extensor muscle strength and patellar tendon mechanical properties were measured over 1 yr in 3-mo intervals. A linear mixed-effects model was used to analyze time-dependent changes and the residuals of the model to quantify fluctuations over time. The cosine similarity (CS) served as a measure of uniformity of the relative changes of tendon force and stiffness. Muscle strength and tendon stiffness increased significantly in both groups (P uniformity of changes of tendon force and stiffness was lower in athletes (CS A, -0.02 ± 0.5; C, 0.5 ± 0.4; P uniformity of muscle and tendon adaptation, which increases the demand on the tendon with potential implications for tendon injury. Copyright © 2016 the American Physiological Society.

  8. Elastic properties of muscle-tendon complex in long-distance runners.

    Science.gov (United States)

    Kubo, K; Kanehisa, H; Kawakami, Y; Fukunaga, T

    2000-02-01

    The purpose of this study was to investigate the elastic properties of muscle-tendon complex (MTC) in knee extensor muscles and the capacity for elastic energy utilization in long-distance runners (LDR) by comparing with data obtained from untrained individuals (CON). The elongation (L) of the tendon and aponeurosis of vastus lateralis muscle during isometric knee extension was determined by real-time brightness mode ultrasonography, while the subjects developed a gradually increasing torque from 0 (relaxed) to maximal effort (MVC) within 7 s. In addition, performances in two kinds of maximal vertical jumps, i.e. squatting (SJ) and counter-movement jumps (CMJ), were measured. The relationship between L muscle and force (F) was curvilinear and consisted of an initial region (toe region), characterized by a large increase in L with increasing F, immediately followed by a linear region. The slope of the regression equation for the L-F relationship in the range 50%-100% of MVC was defined as an index of MTC compliance, where the rate of the changes in L to that in muscle F at every 10% of MVC became almost constant. The maximal L (Lmax) and MTC compliance were significantly lower in LDR than in CON: 29.9 (SD 3.9) mm in LDR compared to 33.3 (SD 5.5) mm in CON for Lmax and 1.55 (SD 0.25) x 10(-2) mm.N-1 in LDR compared to 1.88 (SD 0.82) x 10(-2) mm.N-1 in CON for MTC compliance. Also, LDR showed significantly less elastic energy absorption (Ee) than CON, defined as the area below the L-F relationship curve from 0 to 100% of MVC. Not only jump heights but also the differences between the heights in SJ and CMJ, expressed as the percentage of the height in SJ, were significantly lower in LDR than in CON. The augmentation with counter-movement was significantly correlated to either MTC compliance (r = 0.554, P untrained individuals. These elastic profiles of vastus lateralis muscle in LDR may be associated with their lower performances during CMJ.

  9. The bio-tribological properties of anti-adhesive agents commonly used during tendon repair.

    Science.gov (United States)

    McGonagle, Lorcan; Jones, Michael D; Dowson, Duncan; Theobald, Peter S

    2012-05-01

    Frictional resistance to tendon gliding is minimized by surrounding loose areolar tissue. During periods of prolonged immobilization, for example, post-tendon-repair, adhesions can form between these two adjacent tissues, thereby limiting tendon function. Anti-adhesive agents can be applied during surgery to prevent adhesion formation, whilst reportedly providing some reduction in friction during in vitro tendon-bony pulley investigations. This bio-tribological study evaluates whether application of these agents can improve the lubrication between the tendon and surrounding tissue, thus potentially reducing the risk of re-rupturing the tendon at the repair site. The use of bovine synovial fluid (BSF) enabled an approximation of the in vivo lubrication regime, and subsequent comparison of the performance of three synthetic agents (50 mg/ml 5-fluorouracil; 5 mg/ml hyaluronic acid; ADCON-T/N). Coefficient of friction data was recorded and then compared with the Stribeck curve. BSF generated a fluid film that separated the two surfaces, giving rise to optimal lubrication conditions. This efficient regime was also generated following application of each anti-adhesion agent. The use of phosphate-buffered saline solution in generating only a boundary lubrication regime highlighted the effectiveness of the agents in reducing friction. Hyaluronic acid (5 mg/ml) was marginally deemed the most effective anti-adhesive agent at lubricating the tendon. Subsequently, it is concluded that the application of anti-adhesive agents post-surgery has secondary, tribological benefits that serve to reduce friction, and thus potentially the risk of failure, at the tendon repair site. Copyright © 2011 Orthopaedic Research Society.

  10. Expression of insulin-like growth factor I, insulin-like growth factor binding proteins, and collagen mRNA in mechanically loaded plantaris tendon

    DEFF Research Database (Denmark)

    Olesen, Jens L; Heinemeier, Katja M; Haddad, Fadia

    2006-01-01

    . However, it is not known whether MGF is expressed and upregulated in mechanically loaded tendon. This study examined the effect of mechanical load on tendon collagen mRNA in relation to changes in the IGF-I systems mRNA expression. Data were collected at 2, 4, 8 and 16 days after surgical removal...... of synergistic muscle to the plantaris muscle of the rat, thus increasing the load to plantaris muscle and tendon. Nearly a doubling of the tendon mass was observed after 16 days of loading. A rapid rise in tendon procollagen III mRNA was seen after 2 days whereas the increase in procollagen I m......RNA was significant from day 8. MGF was expressed and upregulated in loaded tendon tissue with a faster response than IGF-I, which was increased from day 8. Finally, IGFBP-4 mRNA was increased with a time pattern similar to procollagen III, whereas IGFBP-5 decreased at day 8. In conclusion, loading of tendon tissue...

  11. Influence of stretching and warm-up on Achilles tendon material properties.

    Science.gov (United States)

    Park, Don Young; Rubenson, Jonas; Carr, Amelia; Mattson, James; Besier, Thor; Chou, Loretta B

    2011-04-01

    Controversy exists on stretching and warm-up in injury prevention. We hypothesized that warm up has a greater effect on Achilles tendon biomechanics than static stretching. This study investigated static stretching and warm-up on Achilles tendon biomechanics in recreational athletes, in vivo. Ten active, healthy subjects, 5 males, 5 females, With a mean age of 22.9 years with no previous Achilles tendon injuries were recruited. Typical stretching and warm-up routines were created. Testing was performed in a randomized cross-over design. A custom-built dynamometer was utilized to perform controlled isometric plantarflexion. A low profile ultrasound probe was utilized to visualize the musculotendinous junction of the medial gastrocnemius. An eight-camera motion capture system was used to capture ankle motion. Custom software calculated Achilles tendon biomechanics. Achilles tendon force production was consistent. No statistically significant differences were detected in stretch, stiffness, and strain between pre-, post-stretching, and post-warm-up interventions. Stretching or warm-up alone, and combined did not demonstrate statistically significant differences. Stretching and warm-up may have an equivalent effect on Achilles tendon biomechanics. Prolonged and more intense protocols may be required for changes to occur. Stretching and warm-up of the Achilles before exercise are commonly practiced. Investigating the effect of stretching and warm-up may shed light on potential injury prevention.

  12. Alteration of the material properties of the normal supraspinatus tendon by nicotine treatment in a rat model

    OpenAIRE

    Ichinose, Ryogo; Sano, Hirotaka; Kishimoto, Koshi N.; Sakamoto, Naoya; Sato, Masaaki; Itoi, Eiji

    2010-01-01

    Background and purpose Several studies have shown that nicotine has a detrimental effect on the development of rotator cuff tear. However, little is known about its mechanism. We evaluated the effect of nicotine on the maximum tensile load, the maximum tensile stress, and the elastic modulus of the supraspinatus tendon in a rat model. Methods 27 rats were randomly assigned to 3 groups. Subcutaneously implanted osmotic pumps delivered two different concentrations of nicotine solution (high dos...

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

    Science.gov (United States)

    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. © 2014 AlphaMed Press.

  14. The Mechanical Properties of Nanowires

    Science.gov (United States)

    Wang, Shiliang; Shan, Zhiwei

    2017-01-01

    Applications of nanowires into future generation nanodevices require a complete understanding of the mechanical properties of the nanowires. A great research effort has been made in the past two decades to understand the deformation physics and mechanical behaviors of nanowires, and to interpret the discrepancies between experimental measurements and theoretical predictions. This review focused on the characterization and understanding of the mechanical properties of nanowires, including elasticity, plasticity, anelasticity and strength. As the results from the previous literature in this area appear inconsistent, a critical evaluation of the characterization techniques and methodologies were presented. In particular, the size effects of nanowires on the mechanical properties and their deformation mechanisms were discussed. PMID:28435775

  15. Exposure of a tendon extracellular matrix to synovial fluid triggers endogenous and engrafted cell death: A mechanism for failed healing of intrathecal tendon injuries.

    Science.gov (United States)

    Garvican, Elaine R; Salavati, Mazdak; Smith, Roger K W; Dudhia, Jayesh

    2017-09-01

    The purpose of this study was to investigate the effect of normal synovial fluid (SF) on exposed endogenous tendon-derived cells (TDCs) and engrafted mesenchymal stem cells (MSCs) within the tendon extracellular matrix. Explants from equine superficial digital flexor (extra-synovial) and deep digital flexor tendons (DDFTs) from the compressed, intra-synovial and the tensile, extra-synovial regions were cultured in allogeneic or autologous SF-media. Human hamstring explants were cultured in allogeneic SF. Explant viability was assessed by staining. Proliferation of equine monolayer MSCs and TDCs in SF-media and co-culture with DDFT explants was determined by alamarblue®. Non-viable Native Tendon matrices (NNTs) were re-populated with MSCs or TDCs and cultured in SF-media. Immunohistochemical staining of tendon sections for the apoptotic proteins caspase-3, -8, and -9 was performed. Contact with autologous or allogeneic SF resulted in rapid death of resident tenocytes in equine and human tendon. SF did not affect the viability of equine epitenon cells, or of MSCs and TDCs in the monolayer or indirect explant co-culture. MSCs and TDCs, engrafted into NNTs, died when cultured in SF. Caspase-3, -8, and -9 expression was the greatest in SDFT explants exposed to allogeneic SF. The efficacy of cells administered intra-synovially for tendon lesion repair is likely to be limited, since once incorporated into the matrix, cells become vlnerable to the adverse effects of SF. These observations could account for the poor success rate of intra-synovial tendon healing following damage to the epitenon and contact with SF, common with most soft tissue intra-synovial pathologies.

  16. Outcomes after knee joint extensor mechanism disruptions: is it better to fracture the patella or rupture the tendon?

    Science.gov (United States)

    Tejwani, Nirmal C; Lekic, Nikola; Bechtel, Christopher; Montero, Nicole; Egol, Kenneth A

    2012-11-01

    The purpose of this study was to compare the outcome after the operative treatment of patella fractures (PFs) as compared with those of quadriceps tendon and patella tendon (PT) ruptures. This pertains to a retrospective case control. The setting was in academic teaching hospitals. Ninety-four patients with 99 extensor mechanism disruptions were treated operatively. Of these, 50 (50%) were PFs; 36 (37%) were quadriceps ruptures; and 13 (13%) were PT ruptures. The patients were evaluated at 6 and 12 months and were tested for range of motion, quadriceps circumference and strength, SF36, Lysholm, and Tegner outcome scores by independent observers. Radiographs of the knee were obtained to assess bony healing, posttraumatic arthritis, and heterotopic ossification. A minimum of 12-month follow-up (range 12-81 months) was available for 76 patients (77%). PFs were seen more commonly in women (P < 0.001) and PT ruptures tended to occur in younger males (P < 0.001), with no difference in the body mass index. Thigh circumference was significantly smaller than normal in PFs at 1 year as compared with tendon injuries. At latest follow-up, there were no significant differences noted with respect to knee range of motion, radiographic arthritis, Tegner, Lysholm, or SF36 scores. There were no significant differences with regard to outcome in patients sustaining these injuries. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

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

    Science.gov (United States)

    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

  18. Tendon Injuries

    Science.gov (United States)

    ... What OT Can Do: Video For Professionals Ethics Tendon Injuries When a person experiences a tendon injury in the hand that affects the ability ... plan. What can a person with a hand tendon injury do? Implement a home exercise program recommended ...

  19. Exploiting elasticity: Modeling the influence of neural control on mechanics and energetics of ankle muscle-tendons during human hopping.

    Science.gov (United States)

    Robertson, Benjamin D; Sawicki, Gregory S

    2014-07-21

    We present a simplified Hill-type model of the human triceps surae-Achilles tendon complex working on a gravitational-inertial load during cyclic contractions (i.e. vertical hopping). Our goal was to determine the role that neural control plays in governing muscle, or contractile element (CE), and tendon, or series elastic element (SEE), mechanics and energetics within a compliant muscle-tendon unit (MTU). We constructed a 2D parameter space consisting of many combinations of stimulation frequency and magnitude (i.e. neural control strategies). We compared the performance of each control strategy by evaluating peak force and average positive mechanical power output for the system (MTU) and its respective components (CE, SEE), force-length (F-L) and -velocity (F-V) operating point of the CE during active force production, average metabolic rate for the CE, and both MTU and CE apparent efficiency. Our results suggest that frequency of stimulation plays a primary role in governing whole-MTU mechanics. These include the phasing of both activation and peak force relative to minimum MTU length, average positive power, and apparent efficiency. Stimulation amplitude was primarily responsible for governing average metabolic rate and within MTU mechanics, including peak force generation and elastic energy storage and return in the SEE. Frequency and amplitude of stimulation both played integral roles in determining CE F-L operating point, with both higher frequency and amplitude generally corresponding to lower CE strains, reduced injury risk, and elimination of the need for passive force generation in the CE parallel elastic element (PEE). Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. DOES AEROBIC EXERCISE TRAINING PROMOTE CHANGES IN STRUCTURAL AND BIOMECHANICAL PROPERTIES OF THE TENDONS IN EXPERIMENTAL ANIMALS? A SYSTEMATIC REVIEW

    Directory of Open Access Journals (Sweden)

    Márcio A. Bezerra

    2012-11-01

    Full Text Available To develop a systematic review to evaluate, through the best scientific evidence available, the effectiveness of aerobic exercise in improving the biomechanical characteristics of tendons in experimental animals. Two independent assessors conducted a systematic search in the databases Medline/PUBMED and Lilacs/BIREME, using the following descriptors of Mesh in animal models. The ultimate load of traction and the elastic modulus tendon were used as primary outcomes and transverse section area, ultimate stress and tendon strain as secondary outcomes. The assessment of risk of bias in the studies was carried out using the following methodological components: light/dark cycle, temperature, nutrition, housing, research undertaken in conjunction with an ethics committee, randomization, adaptation of the animals to the training and preparation for the mechanical test. Eight studies, comprising 384 animals, were selected; it was not possible to combine them into one meta-analysis due to the heterogeneity of the samples. There was a trend to increasing ultimate load without changes in the other outcomes studied. Only one study met more than 80% of the quality criteria. Physical training performed in a structured way with imposition of overloads seems to be able to promote changes in tendon structure of experimental models by increasing the ultimate load supported. However, the results of the influence of exercise on the elastic modulus parameters, strain, transverse section area and ultimate stress, remain controversial and inconclusive. Such a conclusion must be evaluated with reservation as there was low methodological control in the studies included in this review.

  1. The Physiological Mechanisms of Effect of Vitamins and Amino Acids on Tendon and Muscle Healing: A Systematic Review.

    Science.gov (United States)

    Tack, Christopher; Shorthouse, Faye; Kass, Lindsy

    2017-11-15

    To evaluate current literature via systematic review to ascertain whether amino acids/ vitamins provide any influence on musculotendinous healing, and by which physiological mechanisms Methods: EBSCO, PUBMED, Science Direct, Embase Classic/ Embase, and MEDLINE were searched using terms including "vitamins", "amino acids", "healing", "muscle" and "tendon". The primary search had 479 citations, 466 of which were excluded predominantly due to non-randomised design. Randomised human and animal studies investigating all supplement types/ forms of administration were included. Critical appraisal of internal validity was assessed using the Cochrane risk of bias tool or the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) risk of bias tool for human and animal studies, respectively. 2 reviewers performed duel data extraction. Twelve studies met criteria for inclusion: 8 examined tendon healing, 4 examined muscle healing. All studies used animal models, except 2 human trials using a combined integrator. Narrative synthesis was performed via content analysis of demonstrated statistically significant effects, and thematic analysis of proposed physiological mechanisms of intervention. Vitamin C/ taurine demonstrated indirect effects on tendon healing through anti-oxidant activity. Vitamin A/ glycine showed direct effects on extra-cellular matrix tissue synthesis. Vitamin E shows an anti-proliferative influence on collagen deposition. Leucine directly influences signalling pathways to promote muscle protein synthesis. Preliminary evidence exists demonstrating vitamins and amino acids may facilitate multi-level changes in musculotendinous healing; however recommendations on clinical utility should be made with caution. All animal studies and one human study show high risk of bias with moderate inter-observer agreement (k=0.46). Currently, there is limited evidence to support the use of vitamins and amino acids for musculotendinous injury. Both high quality

  2. Tendon collagen synthesis declines with immobilization in elderly humans

    DEFF Research Database (Denmark)

    Dideriksen, Kasper; Boesen, Anders P; Reitelseder, Søren

    2017-01-01

    -80 yr) were randomly assigned to NSAIDs (ibuprofen 1,200 mg/day; Ibu) or placebo (Plc). One lower limb was immobilized in a cast for 2 wk and retrained for 6 wk. Tendon collagen protein synthesis, mechanical properties, size, expression of genes related to collagen turnover and remodeling, and signal...... intensity (from magnetic resonance imaging) were investigated. Tendon collagen synthesis decreased (P ... immobilization in both groups, whereas scleraxis mRNA decreased with inactivity in the Plc group only (P collagen protein synthesis decreased after 2 wk of immobilization, whereas tendon stiffness and modulus were only marginally reduced, and NSAIDs had no influence upon this...

  3. Evaluation of tissue displacement and regional strain in the Achilles tendon using quantitative high-frequency ultrasound.

    Science.gov (United States)

    Bogaerts, Stijn; De Brito Carvalho, Catarina; Scheys, Lennart; Desloovere, Kaat; D'hooge, Jan; Maes, Frederik; Suetens, Paul; Peers, Koen

    2017-01-01

    The Achilles tendon has a unique structure-function relationship thanks to its innate hierarchical architecture in combination with the rotational anatomy of the sub-tendons from the triceps surae muscles. Previous research has provided valuable insight in global Achilles tendon mechanics, but limitations with the technique used remain. Furthermore, given the global approach evaluating muscle-tendon junction to insertion, regional differences in tendon mechanical properties might be overlooked. However, recent advancements in the field of ultrasound imaging in combination with speckle tracking have made an intratendinous evaluation possible. This study uses high-frequency ultrasound to allow for quantification of regional tendon deformation. Also, an interactive application was developed to improve clinical applicability. A dynamic ultrasound of both Achilles tendons of ten asymptomatic subjects was taken. The displacement and regional strain in the superficial, middle and deep layer were evaluated during passive elongation and isometric contraction. Building on previous research, results showed that the Achilles tendon displaces non-uniformly with a higher displacement found in the deep layer of the tendon. Adding to this, a non-uniform regional strain behavior was found in the Achilles tendon during passive elongation, with the highest strain in the superficial layer. Further exploration of tendon mechanics will improve the knowledge on etiology of tendinopathy and provide options to optimize existing therapeutic loading programs.

  4. Mechanical Properties of Materials

    CERN Document Server

    Pelleg, Joshua

    2013-01-01

    The subject of mechanical behavior has been in the front line of basic studies in engineering curricula for many years.  This textbook was written for engineering students with the aim of presenting, in a relatively simple manner, the basic concepts of mechanical behavior in solid materials. A second aim of the book is to guide students in their laboratory experiments by helping them to understand their observations in parallel with the lectures of their various courses; therefore the first chapter of the book is devoted to mechanical testing. Another aim of the book is to provide practicing engineers with basic help to bridge the gap of time that has passed from their graduation up to their actual involvement in engineering work. The book also serves as the basis for more advanced studies and seminars when pursuing courses on a graduate level. The content of this textbook and the topics discussed correspond to courses that are usually taught in universities and colleges all over the world, but with a differ...

  5. Dynamic adaptation of tendon and muscle connective tissue to mechanical loading

    DEFF Research Database (Denmark)

    Mackey, Abigail; Heinemeier, Katja Maria; Koskinen, Satu Osmi Anneli

    2008-01-01

    The connective tissue of tendon and skeletal muscle is a crucial structure for force transmission. A dynamic adaptive capacity of these tissues in healthy individuals is evident from reports of altered gene expression and protein levels of the fibrillar and network-forming collagens, when subjected...... in this article provide strong evidence for the highly adaptable nature of connective tissue in muscle and tendon......., in particular TGF-beta-1, and matrix remodelling enzymes such as MMP-2. Furthermore, it is under hormonal influence. In skeletal muscle, the extracellular matrix demonstrates its potential for cross-talk by regulating the activity of cells with which it is in contact. Taken together, the studies highlighted...

  6. Effect of PNF stretching training on the properties of human muscle and tendon structures.

    Science.gov (United States)

    Konrad, A; Gad, M; Tilp, M

    2015-06-01

    The purpose of this study was to investigate the influence of a 6-week proprioceptive neuromuscular facilitation (PNF) stretching training program on the various parameters of the human gastrocnemius medialis muscle and the Achilles tendon. Therefore, 49 volunteers were randomly assigned into PNF stretching and control groups. Before and after the stretching intervention, we determined the maximum dorsiflexion range of motion (RoM) with the corresponding fascicle length and pennation angle. Passive resistive torque (PRT) and maximum voluntary contraction (MVC) of the musculo-articular complex were measured with a dynamometer. Muscle-tendon junction (MTJ) displacement allowed us to determine the length changes in tendon and muscle, and hence to calculate stiffness. Mean RoM increased from 31.1 ± 7.2° to 33.1 ± 7.2° (P = 0.02), stiffness of the tendon decreased significantly in both active (from 21.1 ± 8.0 to 18.1 ± 5.5 N/mm) and passive (from 12.1 ± 4.9 to 9.6 ± 3.2 N/mm) conditions, and the pennation angle increased from 18.5 ± 1.8° to 19.5 ± 2.1° (P = 0.01) at the neutral ankle position (90°), only in the intervention group, whereas MVC and PRT values remained unchanged. We conclude that a 6-week PNF stretching training program increases RoM and decreases tendon stiffness, despite no change in PRT. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

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

    Science.gov (United States)

    Konrad, A; Stafilidis, S; Tilp, M

    2017-10-01

    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. © 2017 The Authors Scandinavian Journal of Medicine & Science In Sports Published by John Wiley & Sons Ltd.

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

    Science.gov (United States)

    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.

  9. Systemic stiffening of mouse tail tendon is related to dietary advanced glycation end products but not high-fat diet or cholesterol

    DEFF Research Database (Denmark)

    Eriksen, Christian; Svensson, R B; Scheijen, J

    2014-01-01

    Tendon pathology is related to metabolic disease and mechanical overloading, but the effect of metabolic disease on tendon mechanics is unknown. This study investigated the effect of diet and apolipoprotein E deficiency (ApoE(-/-)) on mechanical properties and advanced glycation end product (AGE...

  10. Adipose derived stromal vascular fraction improves early tendon healing: an experimental study in rabbits

    Directory of Open Access Journals (Sweden)

    Mehdi Behfar

    2011-11-01

    Full Text Available Tendon never restores the complete biological and mechanical properties after healing. Bone marrow and recently adipose tissue have been used as the sources of mesenchymal stem cells, which have been proven to enhance tendon healing. Stromal vascular fraction (SVF, derived from adipose tissue by an enzymatic digestion, represents an alternative source of multipotent cells, which undergo differentiation into multiple lineages to be used in regenerative medicine. In the present study, we investigated potentials of this source on tendon healing. Twenty rabbits were divided into control and treatment groups. Five rabbits were used as donors of adipose tissue. The injury model was unilateral complete transection through the middle one third of deep digital flexor tendon. Immediately after suture repair, either fresh stromal vascular fraction from enzymatic digestion of adipose tissue or placebo was intratendinously injected into the suture site in treatments and controls, respectively. Cast immobilization was continued for two weeks after surgery. Animals were sacrificed at the third week and tendons underwent histological, immunohistochemical, and mechanical evaluations. By histology, improved fibrillar organization and remodeling of neotendon were observed in treatment group. Immunohistochemistry revealed an insignificant increase in collagen type III and I expression in treatments over controls. Mechanical testing showed significant increase in maximum load and energy absorption in SVF treated tendons. The present study showed that intratendinous injection of uncultured adipose derived stromal vascular fraction improved structural and mechanical properties of repaired tendon and it could be an effective modality for treating tendon laceration.

  11. Mechanical stimulation (pulsed electromagnetic fields "PEMF" and extracorporeal shock wave therapy "ESWT" and tendon regeneration: a possible alternative.

    Directory of Open Access Journals (Sweden)

    Federica eRosso

    2015-11-01

    Full Text Available The pathogenesis of tendon degeneration and tendinopathy is still partially unclear. However, an active role of metalloproteinases (MMP, growth factors, such as vascular endothelial growth factor (VEGF and a crucial role of inflammatory elements and cytokines was demonstrated. Mechanical stimulation may play a role in regulation of inflammation. In vitro studies demonstrated that both pulsed electromagnetic fields (PEMF and extracorporeal shock wave therapy (ESWT increased the expression of pro-inflammatory cytokine such as interleukin (IL-6 and IL-10. Moreover ESWT increases the expression of growth factors, such as transforming growth factor beta (TGF-beta, Vascular Endothelial Growth Factor (VEGF, and insulin-like growth factor 1 (IGF1, as well as the synthesis of collagen I fibers. These pre-clinical results, in association with several clinical studies, suggest a potential effectiveness of ESWT for tendinopathy treatment. Recently PEMF gained popularity as adjuvant for fracture healing and bone regeneration. Similarly to ESWT, the mechanical stimulation obtained using PEMFs may play a role for treatment of tendinopathy and for tendon regeneration, increasing in-vitro TGF-beta production, as well as scleraxis and collagen I gene expression. In this manuscript the rational of mechanical stimulations and the clinical studies on the efficacy of extracorporeal shock wave (ESW and PEMF will be discussed. However, no clear evidence of a clinical value of ESW and PEMF has been found in literature with regards to the treatment of tendinopathy in human, so further clinical trials are needed to confirm the promising hypotheses concerning the effectiveness of ESWT and PEMF mechanical stimulation.

  12. Tensile force transmission in human patellar tendon fascicles is not mediated by glycosaminoglycans

    DEFF Research Database (Denmark)

    Svensson, René B; Hassenkam, Tue; Hansen, Philip

    2011-01-01

    Correct mechanical function of tendons is essential to human physiology and therefore the mechanical properties of tendon have been a subject of research for many decades now. However, one of the most fundamental questions remains unanswered: How is load transmitted through the tendon? It has been...... change the tendon modulus, relative energy dissipation, peak stress, or peak strain. The effect of deformation rate was not modulated by the treatment either, indicating no effect on viscosity. These results suggest that GAGs cannot be considered mediators of tensile force transmission in the human...... patellar tendon, and as such, force transmission must either take place through other matrix components or the fibrils must be mechanically continuous at least to the tested length of 7 mm....

  13. Comparison of the Achilles tendon moment arms determined using the tendon excursion and three?dimensional methods

    OpenAIRE

    Hashizume, Satoru; Fukutani, Atsuki; Kusumoto, Kazuki; Kurihara, Toshiyuki; Yanagiya, Toshio

    2016-01-01

    Abstract The moment arm of muscle?tendon force is a key parameter for calculating muscle and tendon properties. The tendon excursion method was used for determining the Achilles tendon moment arm (ATMA). However, the accuracy of this method remains unclear. This study aimed to investigate the magnitude of error introduced in determining the ATMA using the tendon excursion method by comparing it with the reference three?dimensional (3D) method. The tendon excursion method determined the ATMA a...

  14. Changes in morphological and elastic properties of patellar tendon in athletes with unilateral patellar tendinopathy and their relationships with pain and functional disability.

    Directory of Open Access Journals (Sweden)

    Zhi Jie Zhang

    Full Text Available Patellar tendinopathy (PT is one of the most common knee disorders among athletes. Changes in morphology and elasticity of the painful tendon and how these relate to the self-perceived pain and dysfunction remain unclear.To compare the morphology and elastic properties of patellar tendons between athlete with and without unilateral PT and to examine its association with self-perceived pain and dysfunction.In this cross-sectional study, 33 male athletes (20 healthy and 13 with unilateral PT were enrolled. The morphology and elastic properties of the patellar tendon were assessed by the grey and elastography mode of supersonic shear imaging (SSI technique while the intensity of pressure pain, self-perceived pain and dysfunction were quantified with a 10-lb force to the most painful site and the Victorian Institute of Sport Assessment-patella (VISA-P questionnaire, respectively.In athletes with unilateral PT, the painful tendons had higher shear elastic modulus (SEM and larger tendon than the non-painful side (p<0.05 or the dominant side of the healthy athletes (p<0.05. Significant correlations were found between tendon SEM ratio (SEM of painful over non-painful tendon and the intensity of pressure pain (rho  = 0.62; p = 0.024, VISA-P scores (rho  = -0.61; p = 0.026, and the sub-scores of the VISA-P scores on going down stairs, lunge, single leg hopping and squatting (rho ranged from -0.63 to -0.67; p<0.05.Athletes with unilateral PT had stiffer and larger tendon on the painful side than the non-painful side and the dominant side of healthy athletes. No significant differences on the patellar tendon morphology and elastic properties were detected between the dominant and non-dominant knees of the healthy control. The ratio of the SEM of painful to non-painful sides was associated with pain and dysfunction among athletes with unilateral PT.

  15. Mechanical Properties of Polymer Concrete

    Directory of Open Access Journals (Sweden)

    Raman Bedi

    2013-01-01

    Full Text Available Polymer concrete was introduced in the late 1950s and became well known in the 1970s for its use in repair, thin overlays and floors, and precast components. Because of its properties like high compressive strength, fast curing, high specific strength, and resistance to chemical attacks polymer concrete has found application in very specialized domains. Simultaneously these materials have been used in machine construction also where the vibration damping property of polymer concrete has been exploited. This review deals with the efforts of various researchers in selection of ingredients, processing parameters, curing conditions, and their effects on the mechanical properties of the resulting material.

  16. Mechanical Properties of Respiratory Muscles

    Science.gov (United States)

    Sieck, Gary C.; Ferreira, Leonardo F.; Reid, Michael B.; Mantilla, Carlos B.

    2014-01-01

    Striated respiratory muscles are necessary for lung ventilation and to maintain the patency of the upper airway. The basic structural and functional properties of respiratory muscles are similar to those of other striated muscles (both skeletal and cardiac). The sarcomere is the fundamental organizational unit of striated muscles and sarcomeric proteins underlie the passive and active mechanical properties of muscle fibers. In this respect, the functional categorization of different fiber types provides a conceptual framework to understand the physiological properties of respiratory muscles. Within the sarcomere, the interaction between the thick and thin filaments at the level of cross-bridges provides the elementary unit of force generation and contraction. Key to an understanding of the unique functional differences across muscle fiber types are differences in cross-bridge recruitment and cycling that relate to the expression of different myosin heavy chain isoforms in the thick filament. The active mechanical properties of muscle fibers are characterized by the relationship between myoplasmic Ca2+ and cross-bridge recruitment, force generation and sarcomere length (also cross-bridge recruitment), external load and shortening velocity (cross-bridge cycling rate), and cross-bridge cycling rate and ATP consumption. Passive mechanical properties are also important reflecting viscoelastic elements within sarcomeres as well as the extracellular matrix. Conditions that affect respiratory muscle performance may have a range of underlying pathophysiological causes, but their manifestations will depend on their impact on these basic elemental structures. PMID:24265238

  17. Mechanical Properties of Composite Materials

    Directory of Open Access Journals (Sweden)

    Mitsuhiro Okayasu

    2014-10-01

    Full Text Available An examination has been made of the mechanical and failure properties of several composite materials, such as a short and a long carbon fiber reinforced plastic (short- and long-CFRP and metal based composite material. The short CFRP materials were used for a recycled CFRP which fabricated by the following process: the CFRP, consisting of epoxy resin with carbon fiber, is injected to a rectangular plate cavity after mixing with acrylonitrile butadiene styrene resin with different weight fractions of CFRP. The fatigue and ultimate tensile strength (UTS increased with increasing CFRP content. These correlations, however, break down, especially for tensile strength, as the CFPR content becomes more than 70%. Influence of sample temperature on the bending strength of the long-CFRP was investigated, and it appears that the strength slightly decreases with increasing the temperature, due to the weakness in the matrix. Broken fiber and pull-out or debonding between the fiber and matrix were related to the main failure of the short- and long-CFRP samples. Mechanical properties of metal based composite materials have been also investigated, where fiber-like high hardness CuAl2 structure is formed in aluminum matrix. Excellent mechanical properties were obtained in this alloy, e.g., the higher strength and the higher ductility, compared tothe same alloy without the fiber-like structure. There are strong anisotropic effects on the mechanical properties due to the fiber-like metal composite in a soft Al based matrix.

  18. Mechanical Properties of Picea sitchensis

    DEFF Research Database (Denmark)

    Bräuner, Lise; Hoffmeyer, Preben; Poulsson, Lise

    2000-01-01

    the requirements at the same level as Danish grown Norway spruce. The study shows that Sitka spruce and Norway spruce of the same origin exhibit highly comparable mechanical properties. Key words: annual ring width, bending strength, characteristic strength, dry density, EN 338, INSTA 142, modulus of elasticity...

  19. Mechanical properties of organic nanofibers

    DEFF Research Database (Denmark)

    Kjelstrup-Hansen, Jakob; Hansen, Ole; Rubahn, H.R.

    2006-01-01

    Intrinsic elastic and inelastic mechanical Properties of individual, self-assembled, quasi-single-crystalline para-hexaphenylene nanofibers supported on substrates with different hydrophobicities are investigated as well as the interplay between the fibers and the underlying substrates. We find...

  20. Mechanical Properties of Composite Materials

    Directory of Open Access Journals (Sweden)

    Mitsuhiro Okayasu

    2014-10-01

    Full Text Available An examination has been made of the mechanical and failure properties of several composite materials, such as a short and a long carbon fiber reinforced plastic (short- and long-CFRP and metal based composite material. The short CFRP materials were used for a recycled CFRP which fabricated by the following process: the CFRP, consisting of epoxy resin with carbon fiber, is injected to a rectangular plate cavity after mixing with acrylonitrile butadiene styrene resin with different weight fractions of CFRP. The fatigue and ultimate tensile strength (UTS increased with increasing CFRP content. These correlations, however, break down, especially for tensile strength, as the CFPR content becomes more than 70%. Influence of sample temperature on the bending strength of the long-CFRP was investigated, and it appears that the strength slightly degreases with increasing the temperature, due to the weakness in the matrix. Broken fiber and pull-out or debonding between the fiber and matrix were related to the main failure of the short- and long-CFRP samples. Mechanical properties of metal based composite materials have been also investigated, where fiber-like high hardness CuAl2 structure is formed in aluminum matrix. Excellent mechanical properties were obtained in this alloy, e.g., the higher strength and the higher ductility, compared tothe same alloy without the fiber-like structure. There are strong anisotropic effects on the mechanical properties due to the fiber-like metal composite in a soft Al based matrix.

  1. Subject-specific tendon-aponeurosis definition in Hill-type model predicts higher muscle forces in dynamic tasks.

    Directory of Open Access Journals (Sweden)

    Pauline Gerus

    Full Text Available Neuromusculoskeletal models are a common method to estimate muscle forces. Developing accurate neuromusculoskeletal models is a challenging task due to the complexity of the system and large inter-subject variability. The estimation of muscles force is based on the mechanical properties of tendon-aponeurosis complex. Most neuromusculoskeletal models use a generic definition of the tendon-aponeurosis complex based on in vitro test, perhaps limiting their validity. Ultrasonography allows subject-specific estimates of the tendon-aponeurosis complex's mechanical properties. The aim of this study was to investigate the influence of subject-specific mechanical properties of the tendon-aponeurosis complex on a neuromusculoskeletal model of the ankle joint. Seven subjects performed isometric contractions from which the tendon-aponeurosis force-strain relationship was estimated. Hopping and running tasks were performed and muscle forces were estimated using subject-specific tendon-aponeurosis and generic tendon properties. Two ultrasound probes positioned over the muscle-tendon junction and the mid-belly were combined with motion capture to estimate the in vivo tendon and aponeurosis strain of the medial head of gastrocnemius muscle. The tendon-aponeurosis force-strain relationship was scaled for the other ankle muscles based on tendon and aponeurosis length of each muscle measured by ultrasonography. The EMG-driven model was calibrated twice - using the generic tendon definition and a subject-specific tendon-aponeurosis force-strain definition. The use of subject-specific tendon-aponeurosis definition leads to a higher muscle force estimate for the soleus muscle and the plantar-flexor group, and to a better model prediction of the ankle joint moment compared to the model estimate which used a generic definition. Furthermore, the subject-specific tendon-aponeurosis definition leads to a decoupling behaviour between the muscle fibre and muscle-tendon unit

  2. A new device combining mechanical stimulation of plantar sole and Achilles' tendon to alleviate the consequences of muscle deconditioning.

    Science.gov (United States)

    Canu, Marie-Hélène; Fryziel, Fabrice; Noel, Jean-Pierre; Tiffreau, Vincent; Digumber, Marc; Bastide, Bruno

    2016-05-01

    Limb immobilization or confinement to bed results in a severe atrophy and weakness of lower leg muscles. Full recovery of muscle strength and physical function is rare and may impact the patient's outcome. Studies performed on rodents have demonstrated that the deleterious structural and functional adaptations which occur during muscle deconditioning can be counteracted through adequate physiological stimuli. Thus, based on this fundamental work, we developed a device that combines mechanical stimulation of proprioceptors located in the plantar sole and Achilles' tendon. The device is adapted to patients immobilized and confined to bed. Stimulations can be applied on muscle in passive state. The protocol is non-invasive and is well accepted by patients. This paper presents the technical features of the device, as well as preliminary results of the first clinical study. This device might allow considering new therapeutic strategies for prevention of atrophy in many pathologies.

  3. Axial speed of sound for the monitoring of injured equine tendons: a preliminary study.

    Science.gov (United States)

    Vergari, Claudio; Pourcelot, Philippe; Ravary-Plumioën, Bérangère; Dupays, Anne-Gaëlle; Jacquet, Sandrine; Audigié, Fabrice; Denoix, Jean-Marie; Laugier, Pascal; Mitton, David; Crevier-Denoix, Nathalie

    2012-01-03

    Equine superficial digital flexor tendons (SDFT) are often injured, and they represent an excellent model for human sport tendinopathies. While lesions can be precisely diagnosed by clinical evaluation and ultrasonography, a prognosis is often difficult to establish; the knowledge of the injured tendon's mechanical properties would help in anticipating the outcome. The objectives of the present study were to compare the axial speed of sound (SOS) measured in vivo in normal and injured tendons and to investigate their relationship with the tendons' mechanical parameters, in order to assess the potential of quantitative axial ultrasound to monitor the healing of the injured tendons. SOS was measured in vivo in the right fore SDFTs of 12 horses during walk, before and 3.5 months after the surgical induction of a bilateral core lesion. The 12 horses were then euthanized, their SDFTs isolated and tested in tension to measure their elastic modulus and maximal load (and corresponding stress). SOS significantly decreased from 2179.4 ± 31.4 m/s in normal tendons to 2065.8 ± 67.1 m/s 3.5 months after the surgical induction, and the tendons' elastic modulus (0.90 ± 0.17 GPa) was found lower than what has been reported in normal tendons. While SOS was not correlated to tendon maximal load and corresponding stress, the SOS normalized on its value in normal tendons was correlated to the tendons' elastic modulus. These preliminary results confirm the potential of axial SOS in helping the functional assessment of injured tendon. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Mechanical Properties of Flexographic Prints

    Directory of Open Access Journals (Sweden)

    Simona Grigaliūnienė

    2014-02-01

    Full Text Available Mechanical properties of paper and flexographic prints madewith different anilox rollers were investigated experimentally.Flexographic prints roughness, breaking force and folding resistancevalues were determined. The results showed that foldingresistance is bigger for machine direction prints than for crossmachine direction prints. Flexographic prints on cardboardsfolding resistance values are different for machine direction andcross machine direction. It was determined that roughness offlexographic prints increases with the amount of ink on aniloxroller. Results were explained by the ink water influence.

  5. Acute effects of static stretching on muscle-tendon mechanics of quadriceps and plantar flexor muscles.

    Science.gov (United States)

    Bouvier, Tom; Opplert, Jules; Cometti, Carole; Babault, Nicolas

    2017-07-01

    This study aimed to determine the acute effects of static stretching on stiffness indexes of two muscle groups with a contrasting difference in muscle-tendon proportion. Eleven active males were tested on an isokinetic dynamometer during four sessions randomly presented. Two sessions were dedicated to quadriceps and the two others to triceps surae muscles. Before and immediately after the stretching procedure (5 × 30 s), gastrocnemius medialis and rectus femoris fascicle length and myotendinous junction elongation were determined using ultrasonography. Passive and maximal voluntary torques were measured. Fascicle and myotendinous junction stiffness indexes were calculated. After stretching, maximal voluntary torque similarly decreased for both muscle groups. Passive torque significantly decreased on triceps surae and remained unchanged on quadriceps muscles. Fascicle length increased similarly for both muscles. However, myotendinous junction elongation remained unchanged for gastrocnemius medialis and increased significantly for rectus femoris muscle. Fascicle stiffness index significantly decreased on medial gastrocnemius and remained unchanged on rectus femoris muscle. In contrast, myotendinous junction stiffness index similarly decreased on both muscles. Depending on the muscle considered, the present results revealed different acute stretching effects. This muscle dependency appeared to affect primarily fascicle stiffness index rather than the myotendinous junction.

  6. Transcription factor EGR1 directs tendon differentiation and promotes tendon repair

    Science.gov (United States)

    Guerquin, Marie-Justine; Charvet, Benjamin; Nourissat, Geoffroy; Havis, Emmanuelle; Ronsin, Olivier; Bonnin, Marie-Ange; Ruggiu, Mathilde; Olivera-Martinez, Isabel; Robert, Nicolas; Lu, Yinhui; Kadler, Karl E.; Baumberger, Tristan; Doursounian, Levon; Berenbaum, Francis; Duprez, Delphine

    2013-01-01

    Tendon formation and repair rely on specific combinations of transcription factors, growth factors, and mechanical parameters that regulate the production and spatial organization of type I collagen. Here, we investigated the function of the zinc finger transcription factor EGR1 in tendon formation, healing, and repair using rodent animal models and mesenchymal stem cells (MSCs). Adult tendons of Egr1–/– mice displayed a deficiency in the expression of tendon genes, including Scx, Col1a1, and Col1a2, and were mechanically weaker compared with their WT littermates. EGR1 was recruited to the Col1a1 and Col2a1 promoters in postnatal mouse tendons in vivo. Egr1 was required for the normal gene response following tendon injury in a mouse model of Achilles tendon healing. Forced Egr1 expression programmed MSCs toward the tendon lineage and promoted the formation of in vitro–engineered tendons from MSCs. The application of EGR1-producing MSCs increased the formation of tendon-like tissues in a rat model of Achilles tendon injury. We provide evidence that the ability of EGR1 to promote tendon differentiation is partially mediated by TGF-β2. This study demonstrates EGR1 involvement in adult tendon formation, healing, and repair and identifies Egr1 as a putative target in tendon repair strategies. PMID:23863709

  7. Can PRP effectively treat injured tendons?

    Science.gov (United States)

    Wang, James H-C

    2014-01-01

    PRP is widely used to treat tendon and other tissue injuries in orthopaedics and sports medicine; however, the efficacy of PRP treatment on injured tendons is highly controversial. In this commentary, I reason that there are many PRP- and patient-related factors that influence the outcomes of PRP treatment on injured tendons. Therefore, more basic science studies are needed to understand the mechanism of PRP on injured tendons. Finally, I suggest that better understanding of the PRP action mechanism will lead to better use of PRP for the effective treatment of tendon injuries in clinics.

  8. Impact of oral contraceptive use and menstrual phases on patellar tendon morphology, biochemical composition and biomechanical properties in female athletes

    DEFF Research Database (Denmark)

    Hansen, Mette; Couppe, Christian; Hansen, Christina S

    2013-01-01

    Introduction: Gender differences exist with regards to ligament and tendon injuries. Lower collagen synthesis has been observed in exercising females vs. males, and in users of oral contraceptives (OC) vs non-users, but it is unknown if OC will influence tendon biomechanics of females undergoing ...

  9. Feasibility of using a hand-held device to characterize tendon tissue biomechanics.

    Directory of Open Access Journals (Sweden)

    Sahand Sohirad

    Full Text Available To examine the feasibility of using the MyotonPRO digital palpation device in measuring the transverse stiffness of tendon tissue.Experimental study.The MyotonPRO was used to measure the stiffness and related properties of ballistics gel in comparison with an external materials testing system (PCB electronics. The device was then used to measure the same properties of avian Achilles tendons before and after the removal of the overlying skin and subcutaneous tissue. Next, the test-retest reliability of the Achilles and patellar tendons was determined in humans. Finally, the stiffness of the Achilles tendon was measured before and after competitive running races of varying distances (10, 21 and 42 km, total number of athletes analyzed = 66.The MyotonPRO demonstrated a high degree of consistency when testing ballistics gel with known viscoelastic properties. The presence of skin overlying the avian Achilles tendon had a statistically significant impact on stiffness (p<0.01 although this impact was of very small absolute magnitude (with skin; 728 Nm ±17 Nm, without skin; Nm 704 Nm ±7 Nm. In healthy adults of normal body mass index (BMI, the reliability of stiffness values was excellent both for the patellar tendon (ICC, 0.96 and the Achilles tendon (ICC,0.96. In the the field study, men had stiffer tendons than women (p<0.05, and the stiffness of the Achilles tendon tended to increase following running (p = 0.052.The MyotonPRO can reliably determine the transverse mechanical properties of tendon tissue. The measured values are influenced by the presence of overlying skin, however this does not appear to compromise the ability of the device to record physiologically and clinically relevant measurements.

  10. The early effects of sustained platelet-derived growth factor administration on the functional and structural properties of repaired intrasynovial flexor tendons: an in vivo biomechanic study at 3 weeks in canines.

    Science.gov (United States)

    Gelberman, Richard H; Thomopoulos, Stavros; Sakiyama-Elbert, Shelly E; Das, Rosalina; Silva, Matthew J

    2007-03-01

    A bioactive fibrin-based delivery system was used to provide sustained administration of platelet-derived growth factor (PDGF-BB) in a clinically relevant model of intrasynovial flexor tendon repair. We hypothesized that PDGF-BB administered in this manner would improve the sutured tendon's functional and structural properties 3 weeks after repair. A delivery system consisting of 30 microL of fibrin matrix, peptide, heparin, and 100 ng of PDGF-BB was incorporated into the repair sites of randomly selected medial or lateral forepaw flexor digitorum profundus tendons of 8 adult mongrel dogs. The remaining forepaw flexor digitorum profundus tendons were repaired without the growth-factor and fibrin-based delivery system and served as controls. The surgically treated forelimbs were treated with controlled passive motion rehabilitation. The animals were killed at 3 weeks, at which time the tendons were tested for range of motion with a motion analysis system and for tensile properties with a materials testing machine. Proximal interphalangeal joint and distal interphalangeal joint rotation values were significantly higher for the PDGF-BB-treated tendons compared with the repair-alone tendons. Excursion values were also significantly higher in the PDGF-BB-treated tendons. There were no significant differences in tensile properties when comparing PDGF-BB-treated with repair-alone tendons. The functional properties of repaired intrasynovial flexor tendons were significantly improved with the sustained administration of PDGF-BB. The failure to achieve improvements in ultimate load, stiffness, and strain in the experimental group may have been due to suboptimal PDGF-BB dosage or suboptimal release kinetics.

  11. Mechanical Properties of Niobium Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Dhakal, Pashupati [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Matalevich, Joseph R. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Myneni, Ganapati Rao [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

    2015-09-01

    The mechanical stability of bulk Nb cavity is an important aspect to be considered in relation to cavity material, geometry and treatments. Mechanical properties of Nb are typically obtained from uniaxial tensile tests of small samples. In this contribution we report the results of measurements of the resonant frequency and local strain along the contour of single-cell cavities made of ingot and fine-grain Nb of different purity subjected to increasing uniform differential pressure, up to 6 atm. Measurements have been done on cavities subjected to different heat treatments. Good agreement between finite element analysis simulations and experimental data in the elastic regime was obtained with a single set of values of Young’s modulus and Poisson’s ratio. The experimental results indicate that the yield strength of medium-purity ingot Nb cavities is higher than that of fine-grain, high-purity Nb.

  12. Incorporation of a Decorin Biomimetic Enhances the Mechanical Properties of Electrochemically Aligned Collagen Threads

    Science.gov (United States)

    Kishore, Vipuil; Paderi, John E.; Akkus, Anna; Smith, Katie M.; Balachandran, Dave; Beaudoin, Stephen; Panitch, Alyssa; Akkus, Ozan

    2011-01-01

    Orientational anisotropy of collagen molecules is integral for the mechanical strength of collagen-rich tissues. We have previously reported a novel methodology to synthesize highly oriented electrochemically aligned collagen (ELAC) threads with mechanical properties converging upon those of native tendon. Decorin, a small leucine rich proteoglycan (SLRP), binds to fibrillar collagen and has been suggested to enhance the mechanical properties of tendon. Based on the structure of natural decorin, we have previously designed and synthesized a peptidoglycan (DS-SILY) that mimics decorin both structurally and functionally. In this study, we investigated the effect of the incorporation of DS-SILY on the mechanical properties and structural organization of ELAC threads. The results indicated that the addition of DS-SILY at a molar ratio of 30:1 (Collagen:DS-SILY) significantly enhanced the ultimate stress and ultimate strain of the ELAC threads. Furthermore, differential scanning calorimetry revealed that the addition of DS-SILY at a molar ratio of 30:1 resulted in a more thermally stable collagen structure. However, addition of DS-SILY at a higher concentration (10:1 Collagen:DS-SILY) yielded weaker threads with mechanical properties comparable to collagen control threads. Transmission emission microscopy revealed that the addition of DS-SILY at a higher concentration (10:1) resulted in pronounced aggregation of collagen fibrils. More importantly, these aggregates were not aligned along the long axis of the ELAC thereby compromising on the overall tensile properties of the material. We conclude that incorporation of an optimal amount of DS-SILY is a promising approach to synthesize mechanically competent collagen based biomaterials for tendon tissue engineering applications. PMID:21356334

  13. Ultrasound elasticity imaging of human posterior tibial tendon

    Science.gov (United States)

    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

  14. Biomimetic Scaffold Design for Functional and Integrative Tendon Repair

    Science.gov (United States)

    Zhang, Xinzhi; Bogdanowicz, Danielle; Erisken, Cevat; Lee, Nancy M.; Lu, Helen H.

    2012-01-01

    Rotator cuff tears represent the most common shoulder injuries in the United States. The debilitating effect of this degenerative condition coupled with the high incidence of failure associated with existing graft choices underscore the clinical need for alternative grafting solutions. The two critical design criteria for the ideal tendon graft would require the graft to not only exhibit physiologically relevant mechanical properties but also be able to facilitate functional graft integration by promoting the regeneration of the native tendon-to-bone interface. Centered on these design goals, this review will highlight current approaches to functional and integrative tendon repair. In particular, the application of biomimetic design principles through the use of nanofiber- and nanocomposite-based scaffolds for tendon tissue engineering will be discussed. This review will begin with nanofiber-based approaches to functional tendon repair, followed by a section highlighting the exciting research on tendon-to-bone interface regeneration, with an emphasis on implementation of strategic biomimicry in nanofiber scaffold design and the concomitant formation of graded multi-tissue systems for integrative soft tissue repair. This review will conclude with a summary and future directions section. PMID:22244070

  15. A mathematical model characterising Achilles tendon dynamics in flexion.

    Science.gov (United States)

    Chatzistefani, N; Chappell, M J; Hutchinson, C; Kletzenbauer, S; Evans, N D

    2017-02-01

    The purpose of this study is to acquire mechanistic knowledge of the gastrocnemius muscle-Achilles tendon complex behaviour during specific movements in humans through mathematical modelling. Analysis of this muscle-tendon complex was performed to see if already existing muscle-tendon models of other parts of the body could be applied to the leg muscles, especially the gastrocnemius muscle-Achilles tendon complex, and whether they could adequately characterise its behaviour. Five healthy volunteers were asked to take part in experiments where dorsiflexion and plantar flexion of the foot were studied. A model of the Achilles tendon-gastrocnemius muscle was developed, incorporating assumptions regarding the mechanical properties of the muscle fibres and the tendinous tissue in series. Ultrasound images of the volunteers, direct measurements and additional mathematical calculations were used to parameterise the model. Ground reaction forces, forces on specific joints and moments and angles for the ankle were obtained from a Vicon 3D motion capture system. Model validation was performed from the experimental data captured for each volunteer and from reconstruction of the movements of specific trajectories of the joints, muscles and tendons involved in those movements. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. [Pathophysiology of overuse tendon injury].

    Science.gov (United States)

    Kannus, P; Paavola, M; Paakkala, T; Parkkari, J; Järvinen, T; Järvinen, M

    2002-10-01

    Overuse tendon injury is one of the most common injuries in sports. The etiology as well as the pathophysiological mechanisms leading to tendinopathy are of crucial medical importance. At the moment intrinsic and extrinsic factors are assumed as mechanisms of overuse tendon injury. Except for the acute, extrinsic trauma, the chronic overuse tendon injury is a multifactorial process. There are many other factors, such as local hypoxia, less of nutrition, impaired metabolism and local inflammatory that may also contribute to the development of tissue damage. The exact interaction of these factors cannot be explained entirely at the moment. Further studies will be necessary in order to get more information.

  17. Muscle and Tendon Adaptation in Adolescence: Elite Volleyball Athletes Compared to Untrained Boys and Girls.

    Science.gov (United States)

    Mersmann, Falk; Charcharis, Georgios; Bohm, Sebastian; Arampatzis, Adamantios

    2017-01-01

    Though the plasticity of human tendons is well explored in adults, it is still unknown how superimposed mechanical loading by means of athletic training affects the properties of tendons during maturation. Due to the increased responsiveness of muscle to mechanical loading, adolescence is an important phase to investigate the effects of training on the mechanical properties of tendons. Hence, in the present study we compared vastus lateralis (VL) architecture, muscle strength of the knee extensor muscles and patellar tendon mechanical properties of male and female adolescent elite athletes to untrained boys and girls. Twenty-one adolescent volleyball athletes (A; 16.7 ± 1 years; 12 boys, 9 girls) and 24 similar-aged controls (C; 16.7 ± 1 years; 12 boys and girls, respectively) performed maximum isometric contractions on a dynamometer for the assessment of muscle strength and, by integrating ultrasound imaging, patellar tendon mechanical properties. Respective joint moments were calculated using an inverse dynamics approach and an electromyography-based estimation of antagonistic contribution. Additionally, the VL pennation angle, fascicle length and muscle-thickness were determined in the inactive state by means of ultrasound. Adolescent athletes produced significantly greater knee extension moments (normalized to body mass) compared to controls (A: 4.23 ± 0.80 Nm/kg, C: 3.57 ± 0.67 Nm/kg; p = 0.004), and showed greater VL thickness and pennation angle (+38% and +27%; p volleyball training provides a more efficient stimulus for muscle compared to tendon adaptation, which results in an increased demand placed upon the tendon by the working muscle in adolescent volleyball athletes. Besides implications for sport performance, these findings might have important consequences for the risk of tendon overuse injury.

  18. Tendon exhibits complex poroelastic behavior at the nanoscale as revealed by high-frequency AFM-based rheology.

    Science.gov (United States)

    Connizzo, Brianne K; Grodzinsky, Alan J

    2017-03-21

    Tendons transmit load from muscle to bone by utilizing their unique static and viscoelastic tensile properties. These properties are highly dependent on the composition and structure of the tissue matrix, including the collagen I hierarchy, proteoglycans, and water. While the role of matrix constituents in the tensile response has been studied, their role in compression, particularly in matrix pressurization via regulation of fluid flow, is not well understood. Injured or diseased tendons and tendon regions that naturally experience compression are known to have alterations in glycosaminoglycan content, which could modulate fluid flow and ultimately mechanical function. While recent theoretical studies have predicted tendon mechanics using poroelastic theory, no experimental data have directly demonstrated such behavior. In this study, we use high-bandwidth AFM-based rheology to determine the dynamic response of tendons to compressive loading at the nanoscale and to determine the presence of poroelastic behavior. Tendons are found to have significant characteristic dynamic relaxation behavior occurring at both low and high frequencies. Classic poroelastic behavior is observed, although we hypothesize that the full dynamic response is caused by a combination of flow-dependent poroelasticity as well as flow-independent viscoelasticity. Tendons also demonstrate regional dependence in their dynamic response, particularly near the junction of tendon and bone, suggesting that the structural and compositional heterogeneity in tendon may be responsible for regional poroelastic behavior. Overall, these experiments provide the foundation for understanding fluid-flow-dependent poroelastic mechanics of tendon, and the methodology is valuable for assessing changes in tendon matrix compressive behavior at the nanoscale. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Tendon Force Transmission at the Nanoscale

    DEFF Research Database (Denmark)

    Svensson, René

    2013-01-01

    of connective tissue function that are poorly understood. One such aspect is the microscopic mechanisms of force transmission through tendons over macroscopic distances. Force transmission is at the heart of tendon function, but the large range of scales in the hierarchical structure of tendons has made...... it difficult to tackle. The tendon hierarchy ranges from molecules (2 nm) over fibrils (200 nm), fibers (2 μm) and fascicles (200 μm) to tendons (10 mm), and to derive the mechanisms of force transmission it is necessary to know the mechanical behavior at each hierarchical level. The aim of the present work...... was to elucidate the mechanisms of force transmission in tendons primarily by investigating the mechanical behavior at the hierarchical level of collagen fibrils. To do so we have developed an atomic force microscopy (AFM) method for tensile testing of native collagen fibrils. The thesis contains five papers...

  20. Cross-linking in collagen by nonenzymatic glycation increases the matrix stiffness in rabbit achilles tendon.

    Science.gov (United States)

    Reddy, G Kesava

    2004-01-01

    Nonenzymatic glycation of connective tissue matrix proteins is a major contributor to the pathology of diabetes and aging. Previously the author and colleagues have shown that nonenzymatic glycation significantly enhances the matrix stability in the Achilles tendon (Reddy et al., 2002, Arch. Biochem. Biophys., 399, 174-180). The present study was designed to gain further insight into glycation-induced collagen cross-linking and its relationship to matrix stiffness in the rabbit Achilles tendon. The glycation process was initiated by incubating the Achilles tendons (n = 6) in phosphate-buffered saline containing ribose, whereas control tendons (n = 6) were incubated in phosphate-buffered saline without ribose. Eight weeks following glycation, the biomechanical attributes as well as the degree of collagen cross-linking were determined to examine the potential associations between matrix stiffness and molecular properties of collagen. Compared to nonglycated tendons, the glycated tendons showed increased maximum load, stress, strain, Young's modulus of elasticity, and toughness indicating that glycation increases the matrix stiffness in the tendons. Glycation of tendons resulted in a considerable decrease in soluble collagen content and a significant increase in insoluble collagen and pentosidine. Analysis of potential associations between the matrix stiffness and degree of collagen cross-linking showed that both insoluble collagen and pentosidine exhibited a significant positive correlation with the maximum load, stress, and strain, Young's modulus of elasticity, and toughness (r values ranging from.61 to.94) in the Achilles tendons. However, the soluble collagen content present in neutral salt buffer, acetate buffer, and acetate buffer containing pepsin showed an inverse relation with the various biomechanical attributes tested (r values ranging from.22 to.84) in the Achilles tendons. The results of the study demonstrate that glycation-induced collagen cross

  1. Investigation of a robust tendon-sheath mechanism for flexible membrane wing application in mini-UAV

    Science.gov (United States)

    Lee, Shian; Tjahjowidodo, Tegoeh; Lee, Hsuchew; Lai, Benedict

    2017-02-01

    Two inherent issues manifest themselves in flying mini-unmanned aerial vehicles (mini-UAV) in the dense area at tropical climate regions, namely disturbances from gusty winds and limited space for deployment tasks. Flexible membrane wing (FMW) UAVs are seen to be potentials to mitigate these problems. FMWs are adaptable to gusty airflow as the wings are able to flex according to the gust load to reduce the effective angle-of-attack, thus, reducing the aerodynamic loads on the wing. On the other hand, the flexible structure is allowing the UAV to fold in a compact package, and later on, the mini-UAV can be deployed instantly from the storage tube, e.g. through a catapult mechanism. This paper discusses the development of an FMW UAV actuated by a tendon-sheath mechanism (TSM). This approach allows the wing to morph to generate a rolling moment, while still allowing the wing to fold. Dynamic characteristics of the mechanism that exhibits the strong nonlinear phenomenon of friction on TSM are modeled and compensated for. A feed-forward controller was implemented based on the identified nonlinear behavior to control the warping position of the wing. The proposed strategy is validated experimentally in a wind tunnel facility by creating a gusty environment that is imitating a realistic gusty condition based upon the results of computational fluid dynamics (CFD) simulation. The results demonstrate a stable and robust wing-warping actuation, even in gusty conditions. Accurate wing-warping can be achieved via the TSM, while also allowing the wings to fold.

  2. Effect of an aqueous extract of Phaseolus vulgaris on the properties of tail tendon collagen of rats with streptozotocin-induced diabetes

    OpenAIRE

    L. Pari; S. Venkateswaran

    2003-01-01

    Changes in the structural and functional properties of collagen caused by advanced glycation might be of importance for the etiology of late complications in diabetes. The present study was undertaken to investigate the influence of oral administration of aqueous pod extract (200 mg/kg body weight) of Phaseolus vulgaris, an indigenous plant used in Ayurvedic Medicine in India, on collagen content and characteristics in the tail tendon of streptozotocin-diabetic rats. In diabetic rats, collage...

  3. Mechanical Properties of Nanocrystal Supercrystals

    Energy Technology Data Exchange (ETDEWEB)

    Tam, Enrico; Podsiadlo, Paul; Shevchenko, Elena; Ogletree, D. Frank; Delplancke-Ogletree, Marie-Paule; Ashby, Paul D.

    2009-12-30

    Colloidal nanocrystals attract significant interest due to their potential applications in electronic, magnetic, and optical devices. Nanocrystal supercrystals (NCSCs) are particularly appealing for their well ordered structure and homogeneity. The interactions between organic ligands that passivate the inorganic nanocrystal cores critically influence their self-organization into supercrystals, By investigating the mechanical properties of supercrystals, we can directly characterize the particle-particle interactions in a well-defined geometry, and gain insight into both the self-assembly process and the potential applications of nanocrystal supercrystals. Here we report nanoindentation studies of well ordered lead-sulfide (Pbs) nanocrystal supercrystals. Their modulus and hardness were found to be similar to soft polymers at 1.7 GPa and 70 MPa respectively and the fractures toughness was 39 KPa/m1/2, revealing the extremely brittle nature of these materials.

  4. Chondroitin sulphate glycosaminoglycans contribute to widespread inferior biomechanics in tendon after focal injury.

    Science.gov (United States)

    Choi, Rachel K; Smith, Margaret M; Martin, Joshua H; Clarke, Jillian L; Dart, Andrew J; Little, Christopher B; Clarke, Elizabeth C

    2016-09-06

    Both mechanical and structural properties of tendon change after injury however the causal relationship between these properties is presently unclear. This study aimed to determine the extent of biomechanical change in post-injury tendon pathology and whether the sulphated glycosaminoglycans (glycosaminoglycans) present are a causal factor in these changes. Equine superficial digital flexor tendons (SDF tendons) were surgically-injured in vivo (n=6 injured, n=6 control). Six weeks later they were harvested and regionally dissected into twelve regions around the lesion (equal medial/lateral, proximal/distal). Glycosaminoglycans were removed by enzymatic (chondroitinase) treatment. Elastic modulus (modulus) and ultimate tensile strength (UTS) were measured under uniaxial tension to failure, and tendon glycosaminoglycan content was measured by spectrophotometry. Compared to healthy tendons, pathology induced by the injury decreased modulus (-38%; 95%CI -49% to -28%; Ptendon. Chondroitinase-mediated glycosaminoglycan removal (50%; 95%CI 21-79%; Ptendons caused a significant increase in modulus (5.6MPa/µg removed; 95%CI 0.31-11; P=0.038) and UTS (1.0MPa per µg removed; 95%CI 0.043-2; P=0.041). These results demonstrate that the chondroitin/dermatan sulphate glycosaminoglycans that accumulate in pathological tendon post-injury are partly responsible for the altered biomechanical properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Mechanical properties of human pulleys.

    Science.gov (United States)

    Lin, G T; Cooney, W P; Amadio, P C; An, K N

    1990-11-01

    In order to determine the mechanical properties of the fibro-osseous pulleys in the hand, the diaphyseal annular pulleys, the volar plate annular pulleys and the cruciate or condensable portions were tested. A custom-made loading device provided proper fit of the soft tissues for a uniform distribution of the pulley load during testing. The A2 pulley was found to be the strongest of the pulleys; the A1 and A4 were the next strongest. The A3 pulley was nearly equal in mean breaking strength to the other annular pulleys, but in absolute breaking load was considerably weaker because of its shortness. The A4 was the least compliant of the pulleys. We concluded that the fibro-osseous A2 and A4 were mechanically stronger and stiffer pulleys than the A1, A3, A5 (volar plate) pulleys. In testing one type of pulley reconstruction, we found that the "belt loop" technique of Karev nearly matched the annular pulleys in strength and energy absorption.

  6. DOES AEROBIC EXERCISE TRAINING PROMOTE CHANGES IN STRUCTURAL AND BIOMECHANICAL PROPERTIES OF THE TENDONS IN EXPERIMENTAL ANIMALS? A SYSTEMATIC REVIEW

    OpenAIRE

    Márcio A. Bezerra; Kamilla D.S. Lira; Patrícia V. C. Silveira; Marcos P.G. Coutinho; Andrea Lemos; Silvia R. A. Moraes

    2012-01-01

    To develop a systematic review to evaluate, through the best scientific evidence available, the effectiveness of aerobic exercise in improving the biomechanical characteristics of tendons in experimental animals. Two independent assessors conducted a systematic search in the databases Medline/PUBMED and Lilacs/BIREME, using the following descriptors of Mesh in animal models. The ultimate load of traction and the elastic modulus tendon were used as primary outcomes and transverse section area,...

  7. Biomechanical properties of suture anchor repair compared with transosseous sutures in patellar tendon ruptures: a cadaveric study.

    Science.gov (United States)

    Ettinger, Max; Dratzidis, Antonios; Hurschler, Christof; Brand, Stephan; Calliess, Tilman; Krettek, Christian; Jagodzinski, Michael; Petri, Maximilian

    2013-11-01

    Ruptures of the patellar tendon are debilitating injuries requiring surgical repair. Reliable data about the most appropriate suture technique and suture material are missing. The standard procedure consists of refixing the tendon with sutures in transpatellar tunnels, sometimes combined with augmentation. Suture anchors provide at least equal results concerning gap formation during cyclic loading and ultimate failure load compared with transosseous suture repair. Controlled laboratory study. A total of 30 human cadaveric patellar tendons underwent tenotomy followed by repair with 5.5-mm titanium suture anchors, 5.5-mm resorbable hydroxyapatite suture anchors, or transpatellar suture tunnels with No. 2 Ultrabraid and the Krackow whipstitch technique. Biomechanical analysis included pretensioning the constructs at 20 N for 30 seconds and then cyclic loading of 250 cycles between 20 and 100 N at 1 Hz in a servohydraulic testing machine with measurement of elongation. After this, ultimate failure load and failure mode analysis was performed. Compared with transosseous sutures, tendon repairs with suture anchors yielded significantly less gap formation during cyclic loading (P suture anchor in the hydroxyapatite anchor group and rupture of the suture in the titanium anchor group and-at lower load to failure-in the transosseous group. Patellar tendon repair with suture anchors yields significantly better biomechanical results than repair with the commonly applied transosseous sutures. These findings may be of relevance for future clinical treatment of patellar tendon ruptures. Randomized controlled clinical trials comparing suture anchors to transosseous suture repair are desirable.

  8. Human flexor tendon tissue engineering: decellularization of human flexor tendons reduces immunogenicity in vivo.

    Science.gov (United States)

    Raghavan, Shyam S; Woon, Colin Y L; Kraus, Armin; Megerle, Kai; Choi, Matthew S S; Pridgen, Brian C; Pham, Hung; Chang, James

    2012-04-01

    In mutilating hand injuries, tissue engineered tendon grafts may provide a reconstructive solution. We have previously described a method to decellularize cadaveric human flexor tendons while preserving mechanical properties and biocompatibility. The purpose of this study is to evaluate the immunogenicity and strength of these grafts when implanted into an immunocompetent rat model. Cadaveric human flexor tendons were divided into two groups. Group 1 was untreated, and Group 2 was decellularized by treatment with sodium dodecyl sulfate (SDS), ethylenediaminetetraacetic acid (EDTA), and peracetic acid (PAA). Both groups were then analyzed for the presence of major histocompatibility complexes by immunohistochemistry (IHC). Pair-matched tendons from each group were then placed into the dorsal subcutaneous tissue and anchored to the spinal ligaments of Wistar rats for 2 or 4 weeks, and harvested. The infiltration of B-cells and macrophages was determined using IHC. The explants where then subjected to mechanical testing to determine the ultimate tensile stress (UTS) and elastic modulus (EM). Statistical analysis was performed using a paired Student's t-test. The decellularization protocol successfully removed cells and MHC-1 complexes. At 2 weeks after implantation, there was increased infiltration of B-cells in Group 1 (untreated) compared with Group 2 (acellular), both in the capsule and tendon substance. There was improved ultimate tensile stress (UTS, 42.7 ± 8.3 vs. 22.8 ± 7.8 MPa, ptendons that were decellularized. At 4 weeks, there was continued B-cell infiltration in Group 1 (untreated) compared with Group 2 (acellular). There was no appreciable difference in macrophage infiltration at both time points. At 4 weeks Group 2 (acellular) demonstrated persistently greater UTS (40.5 ± 9.1 vs. 14.6 ± 4.2 MPa, ptendons that were decellularized with SDS, EDTA, and PAA resulted in removal of cellular antigens and a decreased immune response when placed into Wistar

  9. Investigating tendon mineralisation in the avian hindlimb: a model for tendon ageing, injury and disease

    Science.gov (United States)

    Agabalyan, Natacha A; Evans, Darrell J R; Stanley, Rachael L

    2013-01-01

    Mineralisation of the tendon tissue has been described in various models of injury, ageing and disease. Often resulting in painful and debilitating conditions, the processes underlying this mechanism are poorly understood. To elucidate the progression from healthy tendon to mineralised tendon, an appropriate model is required. In this study, we describe the spontaneous and non-pathological ossification and calcification of tendons of the hindlimb of the domestic chicken (Gallus gallus domesticus). The appearance of the ossified avian tendon has been described previously, although there have been no studies investigating the developmental processes and underlying mechanisms leading to the ossified avian tendon. The tissue and cells from three tendons – the ossifying extensor and flexor digitorum longus tendons and the non-ossifying Achilles tendon – were analysed for markers of ageing and mineralisation using histology, immunohistochemistry, cytochemistry and molecular analysis. Histologically, the adult tissue showed a loss of healthy tendon crimp morphology as well as markers of calcium deposits and mineralisation. The tissue showed a lowered expression of collagens inherent to the tendon extracellular matrix and presented proteins expressed by bone. The cells from the ossified tendons showed a chondrogenic and osteogenic phenotype as well as tenogenic phenotype and expressed the same markers of ossification and calcification as the tissue. A molecular analysis of the gene expression of the cells confirmed these results. Tendon ossification within the ossified avian tendon seems to be the result of an endochondral process driven by its cells, although the roles of the different cell populations have yet to be elucidated. Understanding the role of the tenocyte within this tissue and the process behind tendon ossification may help us prevent or treat ossification that occurs in injured, ageing or diseased tendon. PMID:23826786

  10. Time-dependent ultrasound echo changes occur in tendon during viscoelastic testing.

    Science.gov (United States)

    Duenwald-Kuehl, Sarah; Kobayashi, Hirohito; Lakes, Roderic; Vanderby, Ray

    2012-11-01

    The viscoelastic behavior of tendons has been extensively studied in vitro. A noninvasive method by which to acquire mechanical data would be highly beneficial, as it could lead to the collection of viscoelastic data in vivo. Our lab has previously presented acoustoelasticity as an alternative ultrasound-based method of measuring tendon stress and strain by reporting a relationship between ultrasonic echo intensity (B mode ultrasound image brightness) and mechanical behavior of tendon under pseudoelastic in vitro conditions [Duenwald, S., Kobayashi, H., Frisch, K., Lakes, R., and Vanderby Jr, R., 2011, "Ultrasound Echo is Related to Stress and Strain in Tendon," J. Biomech., 44(3), pp. 424-429]. Viscoelastic properties of the tendons were not examined in that study, so the presence of time-dependent echo intensity changes has not been verified. In this study, porcine flexor tendons were subjected to relaxation and cyclic testing while ultrasonic echo response was recorded. We report that time- and strain history-dependent mechanical properties during viscoelastic testing are manifested in ultrasonic echo intensity changes. We also report that the patterns of the echo intensity changes do not directly mimic the patterns of viscoelastic load changes, but the intensity changed in a repeatable (and therefore predictable) fashion. Although mechanisms need further elucidation, viscoelastic behavior can be anticipated from echo intensity changes. This phenomenon could potentially lead to a more extensive characterization of in vivo tissue behavior.

  11. Muscle and Tendon Adaptation in Adolescence: Elite Volleyball Athletes Compared to Untrained Boys and Girls

    Directory of Open Access Journals (Sweden)

    Falk Mersmann

    2017-06-01

    Full Text Available Though the plasticity of human tendons is well explored in adults, it is still unknown how superimposed mechanical loading by means of athletic training affects the properties of tendons during maturation. Due to the increased responsiveness of muscle to mechanical loading, adolescence is an important phase to investigate the effects of training on the mechanical properties of tendons. Hence, in the present study we compared vastus lateralis (VL architecture, muscle strength of the knee extensor muscles and patellar tendon mechanical properties of male and female adolescent elite athletes to untrained boys and girls. Twenty-one adolescent volleyball athletes (A; 16.7 ± 1 years; 12 boys, 9 girls and 24 similar-aged controls (C; 16.7 ± 1 years; 12 boys and girls, respectively performed maximum isometric contractions on a dynamometer for the assessment of muscle strength and, by integrating ultrasound imaging, patellar tendon mechanical properties. Respective joint moments were calculated using an inverse dynamics approach and an electromyography-based estimation of antagonistic contribution. Additionally, the VL pennation angle, fascicle length and muscle-thickness were determined in the inactive state by means of ultrasound. Adolescent athletes produced significantly greater knee extension moments (normalized to body mass compared to controls (A: 4.23 ± 0.80 Nm/kg, C: 3.57 ± 0.67 Nm/kg; p = 0.004, and showed greater VL thickness and pennation angle (+38% and +27%; p < 0.001. Tendon stiffness (normalized to rest length was also significantly higher in athletes (A: 86.0 ± 27.1 kN/strain, C: 70.2 ± 18.8 kN/strain; p = 0.04, yet less pronounced compared to tendon force (A: 5785 ± 1146 N, C: 4335 ± 1015 N; p < 0.001, which resulted in higher levels of tendon strain during maximum contractions in athletes (A: 8.0 ± 1.9%, C: 6.4 ± 1.8%; p = 0.008. We conclude that athletic volleyball training provides a more efficient stimulus for muscle

  12. Achilles Tendon Rupture

    Science.gov (United States)

    ... Achilles tendon rupture. Obesity. Excess weight puts more strain on the tendon. Prevention To reduce your chance of developing Achilles tendon problems, follow these tips: Stretch and strengthen calf muscles. Stretch your calf until you feel a noticeable ...

  13. Posterior Tibial Tendon Dysfunction

    Science.gov (United States)

    .org Posterior Tibial Tendon Dysfunction Page ( 1 ) Posterior tibial tendon dysfunction is one of the most common problems of the foot and ankle. It occurs when the posterior tibial tendon becomes inflamed or torn. As a result, the ...

  14. Achilles tendon repair

    Science.gov (United States)

    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 ...

  15. Selected mechanical properties of modified beech wood

    Directory of Open Access Journals (Sweden)

    Jiří Holan

    2008-01-01

    Full Text Available This thesis deals with an examination of mechanical properties of ammonia treated beach wood with a trademark Lignamon. For determination mechanical properties were used procedures especially based on ČSN. From the results is noticeable increased density of wood by 22% in comparison with untreated beach wood, which makes considerable increase of the most mechanical wood properties. Considering failure strength was raised by 32% and modulus of elasticity was raised at average about 46%.

  16. Bond Performance of Sand Coated UHM CFRP Tendons in High Performance Concrete

    Directory of Open Access Journals (Sweden)

    Tobias Dominik Lämmlein

    2017-02-01

    Full Text Available The bond behaviour of novel, sand-coated ultra-high modulus (UHM carbon fibre reinforced polymers (CFRP tendons to high performance concrete (HPC was studied by a combined numerical and experimental approach. A series of pull-out tests revealed that the failure type can vary between sudden and continuous pull-out depending on the chosen sand coating grain size. Measuring the same shear stress vs. tendon draw-in (τ-δ curves in the same test set-up, for sand coated CFRP tendons with a longitudinal stiffness of 137 and 509 GPa, respectively, indicated that the absolute bond strength in both cases was not influenced by the tendon’s stiffness. However, the τ-δ curves significantly differed in terms of the draw-in rate, showing higher draw-in rate for the UHM CFRP tendon. With the aid of X-ray computed tomography (CT, scanning electron microscopy (SEM and visual analysis methods, the bond failure interface was located between the CFRP tendon and the surrounding sand-epoxy layer. For further investigation, a simplified finite element analysis (FEA of the tendon pull-out was performed using a cohesive surface interaction model and the software Abaqus 6.14. A parametric study, varying the tendon-related material properties, revealed the tendon’s longitudinal stiffness to be the only contributor to the difference in the τ-δ curves found in the experiments, thus to the shear stress transfer behaviour between the CFRP tendon and the concrete. In conclusion, the excellent bond of the sand-coated UHM CFRP tendons to HPC as well as the deeper insight in the bond failure mechanism encourages the application of UHM CFRP tendons for prestressing applications.

  17. Histologic pattern of biomechanic properties of the carbon fiber-augmented ligament tendon. A laboratory and clinical study.

    Science.gov (United States)

    Mendes, D G; Iusim, M; Angel, D; Rotem, A; Roffman, M; Grishkan, A; Mordohohovich, D; Boss, J

    1985-06-01

    Implantation of carbon fiber tow (CFT) for ligament and tendon augmentation was investigated in ten dogs and 45 patients. CFT produced a new structure with a remarkably consistent structural pattern. The basic pattern of the CFT-augmented unit consisted of a core of carbon fiber surround by concentric layers of fibroblasts and collagen fibers. This unit structure was developed from continuous irritation of physical structure of the carbon fiber. In dogs, ultimate tensile strength of the augmented tendon one year after surgery averaged 88% of natural tendon. Digestion of the connective tissue component of the CFT unit exposed the original carbon fiber tow. The connective tissue-free CFT maintained its original tensile strength. The continuous production of collagenous tissue surrounding carbon fibers produced a ligamentous structure that was physiologically compatible and biomechanically sufficient.

  18. Research on mechanical properties of corn stalk

    Science.gov (United States)

    Zhang, Kaifei; He, Yujing; Zhang, Hongmei; Li, He

    2017-03-01

    Many domestic scholars have studied on straw utilization from lodging resistance, by breeding agricultural experts to optimization parameters, which selected by agricultural mechanical experts and efficient utilization after the harvest crush. Therefore, the study of the mechanical properties of corn stalks has great prospects. It can provide the basis for the design of agricultural machinery and comprehensive utilization of straw that study the relationship between the properties of the corn stalk and the mechanical properties. In this paper, the radial compression and bending mechanical properties of corn stalk was conducted by universal material testing machine, which contributes to the increase of corn crop and provides basis for the development of equipment.

  19. Collagen Structure of Tendon Relates to Function

    Directory of Open Access Journals (Sweden)

    Marco Franchi

    2007-01-01

    Full Text Available A tendon is a tough band of fibrous connective tissue that connects muscle to bone, designed to transmit forces and withstand tension during muscle contraction. Tendon may be surrounded by different structures: 1 fibrous sheaths or retinaculae; 2 reflection pulleys; 3 synovial sheaths; 4 peritendon sheaths; 5 tendon bursae. Tendons contain a few cells, mostly represented by tenoblasts along with endothelial cells and some chondrocytes; b proteoglycans (PGs, mainly decorin and hyaluronan, and c collagen, mostly type I. Tendon is a good example of a high ordered extracellular matrix in which collagen molecules assemble into filamentous collagen fibrils (formed by microfibrils which aggregate to form collagen fibers, the main structural components. It represents a multihierarchical structure as it contains collagen molecules arranged in fibrils then grouped in fibril bundles, fascicles and fiber bundles that are almost parallel to the long axis of the tendon, named as primary, secondary and tertiary bundles. Collagen fibrils in tendons show prevalently large diameter, a D-period of about 67 nm and appear built of collagen molecules lying at a slight angle (< 5°. Under polarized light microscopy the collagen fiber bundles appear crimped with alternative dark and light transverse bands. In recent studies tendon crimps observed via SEM and TEM show that the single collagen fibrils suddenly changing their direction contain knots. These knots of collagen fibrils inside each tendon crimp have been termed “fibrillar crimps”, and even if they show different aspects they all may fulfil the same functional role. As integral component of musculoskeletal system, the tendon acts to transmit muscle forces to the skeletal system. There is no complete understanding of the mechanisms in transmitting/absorbing tensional forces within the tendon; however it seems likely that a flattening of tendon crimps may occur at a first stage of tendon stretching

  20. Growth hormone stimulates the collagen synthesis in human tendon and skeletal muscle without affecting myofibrillar protein synthesis

    DEFF Research Database (Denmark)

    Doessing, Simon; Heinemeier, Katja; Holm, Lars

    2010-01-01

    matrix collagen synthesis in skeletal muscle and tendon, but without any effect upon myofibrillar protein synthesis. The results suggest that GH is more important in strengthening the matrix tissue than for muscle cell hypertrophy in adult human musculotendinous tissue.......In skeletal muscle and tendon the extracellular matrix confers important tensile properties and is crucially important for tissue regeneration after injury. Musculoskeletal tissue adaptation is influenced by mechanical loading, which modulates the availability of growth factors, including growth...... young individuals. rhGH administration caused an increase in serum GH, serum IGF-I, and IGF-I mRNA expression in tendon and muscle. Tendon collagen I mRNA expression and tendon collagen protein synthesis increased by 3.9-fold and 1.3-fold, respectively (P muscle collagen I m...

  1. Biochemical organization of single motor units in two multi-tendoned muscles of the cat distal forelimb.

    Science.gov (United States)

    Fritz, N; Schmidt, C; Yamaguchi, T

    1992-01-01

    In anesthetized cats single motor units (MUs) of the extensor carpi ulnaris (ECU) and extensor digitorum communis (EDC) muscles were selectively activated by stimulation of cervical ventral root filaments. The distribution of force developed by single MUs at the four distal tendons of the EDC muscle and at three portions of the distal tendon of the ECU muscle was analysed. In general, single MUs of both muscles distributed force over all tendons in a unimodal pattern, with the maximal force levels generated at one specific tendon which was termed the best-tendon. Distributions of force were quantitatively described by a parameter representing the mean direction of force output (output-index) and a further one representing the dispersion of force over the distal tendons (divergence). Generally, these parameters and the best-tendon remained stable when a MU was stimulated at different frequencies, but varied from MU to MU. Despite the general stability of the force distribution, slight systematic changes were regularly found in EDC MUs, when they developed a higher amount of force due to a higher frequency of stimulation: the relative amount of force at the best-tendon increased; e.g. the MUs got more selective for the best-tendon. These changes were partly due to overcoming mechanical cross-coupling between neighbouring compartments of the EDC muscle. Such changes of force distribution were only found in a part of the ECU MUs; other ECU MUs did not change their force distribution at all or became less selective for the best-tendon. The phenomenon that MUs of multi-tendoned muscles distribute their force output to the distal tendons in specific patterns is probably due to mechanical partitioning of the parent muscles: the localization of spatial territories of MUs within different anatomical muscle compartments should correspond to the best-tendon. Complex mechanisms allowing passive transmission of force from limited territories along the transverse axis of both

  2. Transcription factor EGR1 directs tendon differentiation and promotes tendon repair

    National Research Council Canada - National Science Library

    Guerquin, Marie-Justine; Charvet, Benjamin; Nourissat, Geoffroy; Havis, Emmanuelle; Ronsin, Olivier; Bonnin, Marie-Ange; Ruggiu, Mathilde; Olivera-Martinez, Isabel; Robert, Nicolas; Lu, Yinhui; Kadler, Karl E; Baumberger, Tristan; Doursounian, Levon; Berenbaum, Francis; Duprez, Delphine

    2013-01-01

    Tendon formation and repair rely on specific combinations of transcription factors, growth factors, and mechanical parameters that regulate the production and spatial organization of type I collagen...

  3. Effects of short duration static stretching on jump performance, maximum voluntary contraction, and various mechanical and morphological parameters of the muscle?tendon unit of the lower extremities

    OpenAIRE

    Stafilidis, Savvas; Tilp, Markus

    2014-01-01

    Purpose Static stretching is used in sport practice but it has been associated with decrements in force and performance. Therefore, we examined the effect of short duration static stretch on the mechano-morphological properties of the m. vastus lateralis (VL) muscle tendon unit (MTU) and on the jumping performance. Methods Eight males and three females (mean???SD, 25.5???3.1?years) stretched their lower legs for a 15 or 60?s duration or acted as their own control without stretching in a rando...

  4. A benchtop biorobotic platform for in vitro observation of muscle-tendon dynamics with parallel mechanical assistance from an elastic exoskeleton.

    Science.gov (United States)

    Robertson, Benjamin D; Vadakkeveedu, Siddarth; Sawicki, Gregory S

    2017-05-24

    We present a novel biorobotic framework comprised of a biological muscle-tendon unit (MTU) mechanically coupled to a feedback controlled robotic environment simulation that mimics in vivo inertial/gravitational loading and mechanical assistance from a parallel elastic exoskeleton. Using this system, we applied select combinations of biological muscle activation (modulated with rate-coded direct neural stimulation) and parallel elastic assistance (applied via closed-loop mechanical environment simulation) hypothesized to mimic human behavior based on previously published modeling studies. These conditions resulted in constant system-level force-length dynamics (i.e., stiffness), reduced biological loads, increased muscle excursion, and constant muscle average positive power output-all consistent with laboratory experiments on intact humans during exoskeleton assisted hopping. Mechanical assistance led to reduced estimated metabolic cost and MTU apparent efficiency, but increased apparent efficiency for the MTU+Exo system as a whole. Findings from this study suggest that the increased natural resonant frequency of the artificially stiffened MTU+Exo system, along with invariant movement frequencies, may underlie observed limits on the benefits of exoskeleton assistance. Our novel approach demonstrates that it is possible to capture the salient features of human locomotion with exoskeleton assistance in an isolated muscle-tendon preparation, and introduces a powerful new tool for detailed, direct examination of how assistive devices affect muscle-level neuromechanics and energetics. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Acute Effects of Stretching on Passive Properties of Human Gastrocnemius Muscle-Tendon Unit: Analysis of Differences Between Hold-Relax and Static Stretching.

    Science.gov (United States)

    Nakamura, Masatoshi; Ikezoe, Tome; Tokugawa, Takahiro; Ichihashi, Noriaki

    2015-08-01

    Hold-relax stretching (HRS) and static stretching (SS) are commonly used to increase joint range of motion (ROM) and decrease muscle stiffness. However, whether there are differences between acute effects of HRS and SS on end ROM, passive torque, and muscle stiffness is unclear. In addition, any differences between the mechanisms by which HRS and SS lead to an increase in end ROM are unclear. To compare the acute effects of HRS and SS on the passive properties of the gastrocnemius muscle-tendon unit (MTU), end ROM, passive torque, and muscle stiffness in vivo and to investigate the factors involved in increasing end ROM. Crossover experimental design. 30 healthy men (21.7 ± 1.2 y) with no history of neuromuscular disease or musculoskeletal injury involving the lower limbs. Both HRS and SS of 30 s were repeated 4 times, lasting a total of 2 min. End ROM, passive torque, and muscle stiffness were measured during passive ankle dorsiflexion using a dynamometer and ultrasonography before and immediately after HRS and SS. The results showed that end ROM and passive torque at end ROM significantly increased immediately after both HRS and SS, whereas muscle stiffness significantly decreased. In addition, the percentage change in passive torque at end ROM on use of the HRS technique was significantly higher than that after use of the SS technique. However, the percentage change in muscle stiffness after SS was significantly higher than that with HRS. These results suggest that both HRS and SS can effectively decrease muscle stiffness of the gastrocnemius MTU and that HRS induces a change in the passive torque at end ROM--i.e., sensory perception--rather than changing muscle stiffness.

  6. Anterior cruciate ligament- and hamstring tendon- derived cells: in vitro differential properties of cells involved in ACL reconstruction

    NARCIS (Netherlands)

    Ghebes, C.A.; Kelder, C.; Schot, T.; Renard, A.J.S.; Pakvis, D.F.M.; Fernandes, H.; Saris, Daniël B.F.

    2015-01-01

    Anterior cruciate ligament (ACL) reconstruction involves the replacement of the torn ligament with a new graft, often a hamstring tendon (HT). Described as similar, the ACL and HT have intrinsic differences related to their distinct anatomical locations. From a cellular perspective, identifying

  7. Flexor tendon physiology: tendon nutrition and cellular activity in injury and repair.

    Science.gov (United States)

    Gelberman, R H

    1985-01-01

    Scientific studies of the past 20 years have done much to redefine the mechanisms by which flexor tendons heal. Several points have become increasingly clear: Flexor tendons are nourished to a greater extent by synovial fluid diffusion than vascular perfusion. Tendon cells are capable of proliferating, producing collagen, and reconstructing their own gliding surface in the absence of adhesion ingrowth. The key to a successful outcome after flexor tendon repair appears to be an early restoration of tendon continuity, reconstruction of the sheath, if possible, and early passive mobilization. This complex stimulates the tendon's intrinsic repair potential, which is contained within the cells of the tendon itself but appears to be expressed only under ideal experimental and clinical situations.

  8. From Tendon Injury to Collagen-based Tendon Regeneration: Overview and Recent Advances.

    Science.gov (United States)

    Rieu, Clement; Picaut, Lise; Mosser, Gervaise; Trichet, Lea

    2017-01-01

    Tendon injury is a clinical, societal and economical issue. Moreover, tendon repair represents an important clinical challenge, partly due to the mechanical constraints that occur at the junctions with muscle and bone. Several strategies have been developed for tendon repair. In this review, we first assess the importance of tendon injuries from different sites and their causes. After a short overview of tendon three-dimensional organization, the complexity of the perfect repair quest is presented ranging from current clinical procedures to new engineering scaffolds. We then sum up tendon engineering requirements and focus on new collagen-based scaffolds, which raise promising prospects to mimic and repair tendon. In particular, we survey quantitatively a large panel of techniques to produce these scaffolds, detailing their principle and recent improvements. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  9. Muscle and tendon adaptation in adolescent athletes: A longitudinal study.

    Science.gov (United States)

    Mersmann, F; Bohm, S; Schroll, A; Boeth, H; Duda, G N; Arampatzis, A

    2017-01-01

    There is evidence that a non-uniform adaptation of muscle and tendon in young athletes results in increased tendon stress during mid-adolescence. The present longitudinal study investigated the development of the morphological and mechanical properties of muscle and tendon of volleyball athletes in a time period of 2 years from mid-adolescence to late adolescence. Eighteen elite volleyball athletes participated in magnetic resonance imaging and ultrasound-dynamometry sessions to determine quadriceps femoris muscle strength, vastus lateralis, medialis and intermedius morphology, and patellar tendon mechanical and morphological properties in mid-adolescence (16 ± 1 years) and late adolescence (18 ± 1 years). Muscle strength, anatomical cross-sectional area (CSA), and volume showed significant (P muscle. These adaptive processes may compensate the unfavorable relation of muscle strength and tendon loading capacity in mid-adolescence and might have implications on athletic performance and tendon injury risk. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Firm anchoring between a calcium phosphate-hybridized tendon and bone for anterior cruciate ligament reconstruction in a goat model

    Energy Technology Data Exchange (ETDEWEB)

    Mutsuzaki, Hirotaka [Department of Orthopaedic Surgery, Ibaraki Prefectural University of Health Sciences, 4669-2 Ami Ami-machi, Inashiki-gun, Ibaraki 300-0394 (Japan); Sakane, Masataka; Ochiai, Naoyuki [Department of Orthopaedic Surgery, Institute of Clinical Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575 (Japan); Hattori, Shinya; Kobayashi, Hisatoshi, E-mail: sakane-m@md.tsukuba.ac.j [Biomaterial Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2009-08-15

    Using an alternative soaking process improved the tendon-bone attachment for a calcium phosphate (CaP)-hybridized tendon graft. We characterized the deposited CaP on and in tendons and analyzed the histology and mechanical properties of the tendon-bone interface in anterior cruciate ligament (ACL) reconstruction in goats. The tendon grafts to be implanted were soaked ten times alternately in a Ca-containing solution and a PO{sub 4}-containing solution for 30 s each. Needlelike CaP nanocrystals including low-crystalline apatite were deposited on and between collagen fibrils from the surface to a depth of 200{mu}m inside the tendon. The structure resembles the extracellular matrix of bone. In animal experiments, the CaP-hybridized tendon directly bonded with newly formed bone at 6 weeks (n = 3), while fibrous bonding was observed in the control (n = 3). The ultimate failure load was not statistically different between the CaP (n = 7) and control (n = 7). However, in the failure mode, all the tendon-bone interfaces were intact in the CaP group, while three of seven specimens were pulled out from bone tunnels in the control. The result suggested that the strength of the tendon-bone interface in the CaP group is superior to that in the control group. Clinically, firm tendon-bone anchoring may lead to good results without the knee instability associated with the loosening of the bone-tendon junction in ACL reconstruction.

  11. Simulation of tendon energy storage in pedaling

    DEFF Research Database (Denmark)

    Rasmussen, John; Damsgaard, Michael; Christensen, Søren Tørholm

    2001-01-01

    system is based on inverse dynamics, where the redundancy problem is solved by a minimum fatigue criterion guaranteeing maximuminter-muscular collaboration. The tendons are assumed to be linearly elastic. It is concluded that tendon elasticity is responsible for metabolic power loss......The role of elastic energy stored in tendons during pedaling is investigated by means of numerical simulation using the AnyBody body modeling system. The loss of metabolic energy due to tendon elasticity is computed and compared to the mechanical work involved in the process. The AnyBody simulation...

  12. Strain mapping in the Achilles tendon - A systematic review.

    Science.gov (United States)

    Bogaerts, Stijn; Desmet, Hannelore; Slagmolen, Pieter; Peers, Koen

    2016-06-14

    Achilles tendinopathy remains one of the most prevalent overuse injuries in elite as well as recreational athletes. Regardless of the fact that the aetiology of tendinopathy has not been fully understood, therapeutic mechanical loading programs have emerged as being the treatment of choice. In this light, mechanical properties of the tendon and their response to changes in loading or unloading have been the subject of many previous investigations. One of these properties often investigated is strain, a measure of relative deformation. By means of a systematic review, an overview was given of research in this field, with a primary objective to list the methods used and secondary aim to synthesize data on strain mapping in the Achilles tendon. Following the guidelines of the PRISMA statement, 47 articles were found appropriate for qualitative assessment. Achilles tendon strain has been investigated across a variety of contexts, including the response to exercise, walking, unloading, ageing, hormonal changes and weight. Only three studies investigated the effect of the presence of tendinopathy on strain. Ultrasound was the most often used imaging modality to measure or estimate strain. Further methodological parameters, e.g. the location of measurement, differed greatly between all different studies. Nearly all studies considered global strain. Some studies investigated the transverse strain response of the Achilles tendon. Recently, however, the role of local - intratendinous - strain distribution has been found to be of critical importance and further studies should focus on imaging modalities to investigate these local changes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Flexor tendon nutrition.

    Science.gov (United States)

    Manske, P R; Lesker, P A

    1985-02-01

    The concepts regarding nutrient pathways to flexor tendons within the digital sheath are reviewed. Historically, both diffusion and perfusion have been considered significant pathways to the flexor tendon. Theories of tendon healing and adhesion formation, as well as techniques employed by the surgeon in the repair of tendons, are based on these concepts.

  14. Iliopsoas Tendon Reformation after Psoas Tendon Release

    Directory of Open Access Journals (Sweden)

    K. Garala

    2013-01-01

    Full Text Available Internal snapping hip syndrome, or psoas tendonitis, is a recognised cause of nonarthritic hip pain. The majority of patients are treated conservatively; however, occasionally patients require surgical intervention. The two surgical options for iliopsoas tendinopathy are step lengthening of the iliopsoas tendon or releasing the tendon at the lesser trochanter. Although unusual, refractory snapping usually occurs soon after tenotomy. We report a case of a 47-year-old active female with internal snapping and pain following an open psoas tenotomy. Postoperatively she was symptom free for 13 years. An MRI arthrogram revealed reformation of a pseudo iliopsoas tendon reinserting into the lesser trochanter. The pain and snapping resolved after repeat iliopsoas tendon release. Reformation of tendons is an uncommon sequela of tenotomies. However the lack of long-term studies makes it difficult to calculate prevalence rates. Tendon reformation should be included in the differential diagnosis of failed tenotomy procedures after a period of symptom relief.

  15. Animal Models for Tendon Repair Experiments: A Comparison of Pig, Sheep and Human Deep Flexor Tendons in Zone II.

    Science.gov (United States)

    Peltz, Tim Sebastian; Hoffman, Stuart William; Scougall, Peter James; Gianoutsos, Mark Peter; Savage, Robert; Oliver, Rema Antoinette; Walsh, William Robert

    2017-09-01

    This laboratory study compared pig, sheep and human deep flexor tendons in regards to their biomechanical comparability. To investigate the relevant biomechanical properties for tendon repair experiments, the tendons resistance to cheese-wiring (suture drag/splitting) was assessed. Cheese-wiring of a suture through a tendon is an essential factor for repair gapping and failure in a tendon repair. Biomechanical testing showed that forces required to pulling a uniform suture loop through sheep or pig tendons in Zone II were higher than in human tendons. At time point zero of testing these differences did not reach statistical significance, but differences became more pronounced when forces were measured beyond initial cheese-wiring (2 mm, 5 mm and 10 mm). The stronger resistance to cheese-wiring was more pronounced in the pig tendons. Also regarding size and histology, sheep tendons were more comparable to human tendons than pig tendons. Differences in tendon bio-properties should be kept in mind when comparing and interpreting the results of laboratory tendon experiments.

  16. Peroneal tendon disorders

    OpenAIRE

    Davda, Kinner; Malhotra, Karan; O'Donnell, Paul; Singh, Dishan; Cullen, Nicholas

    2017-01-01

    Pathological abnormality of the peroneal tendons is an under-appreciated source of lateral hindfoot pain and dysfunction that can be difficult to distinguish from lateral ankle ligament injuries. Enclosed within the lateral compartment of the leg, the peroneal tendons are the primary evertors of the foot and function as lateral ankle stabilisers. Pathology of the tendons falls into three broad categories: tendinitis and tenosynovitis, tendon subluxation and dislocation, and tendon splits and ...

  17. Robot Arm with Tendon Connector Plate and Linear Actuator

    Science.gov (United States)

    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.

  18. Endoscopic adhesiolysis for extensive tibialis posterior tendon and Achilles tendon adhesions following compound tendon rupture

    OpenAIRE

    Lui, Tun Hing

    2013-01-01

    Tendon adhesion is one of the most common causes of disability following tendon surgery. A case of extensive peritendinous adhesions of the Achilles tendon and tibialis posterior tendon after compound rupture of the tendons was reported. This was managed by endoscopic adhesiolysis of both tendons. The endoscopic approach allows early postoperative mobilisation which can relieve the tendon adhesion.

  19. Mechanical properties and cellular response of novel electrospun nanofibers for ligament tissue engineering: Effects of orientation and geometry.

    Science.gov (United States)

    Pauly, Hannah M; Kelly, Daniel J; Popat, Ketul C; Trujillo, Nathan A; Dunne, Nicholas J; McCarthy, Helen O; Haut Donahue, Tammy L

    2016-08-01

    Electrospun nanofibers are a promising material for ligamentous tissue engineering, however weak mechanical properties of fibers to date have limited their clinical usage. The goal of this work was to modify electrospun nanofibers to create a robust structure that mimics the complex hierarchy of native tendons and ligaments. The scaffolds that were fabricated in this study consisted of either random or aligned nanofibers in flat sheets or rolled nanofiber bundles that mimic the size scale of fascicle units in primarily tensile load bearing soft musculoskeletal tissues. Altering nanofiber orientation and geometry significantly affected mechanical properties; most notably aligned nanofiber sheets had the greatest modulus; 125% higher than that of random nanofiber sheets; and 45% higher than aligned nanofiber bundles. Modifying aligned nanofiber sheets to form aligned nanofiber bundles also resulted in approximately 107% higher yield stresses and 140% higher yield strains. The mechanical properties of aligned nanofiber bundles were in the range of the mechanical properties of the native ACL: modulus=158±32MPa, yield stress=57±23MPa and yield strain=0.38±0.08. Adipose derived stem cells cultured on all surfaces remained viable and proliferated extensively over a 7 day culture period and cells elongated on nanofiber bundles. The results of the study suggest that aligned nanofiber bundles may be useful for ligament and tendon tissue engineering based on their mechanical properties and ability to support cell adhesion, proliferation, and elongation. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  2. Evidence of imbalanced adaptation between muscle and tendon in adolescent athletes.

    Science.gov (United States)

    Mersmann, F; Bohm, S; Schroll, A; Boeth, H; Duda, G; Arampatzis, A

    2014-08-01

    Adolescence may be regarded as a critical phase of tissue plasticity in young growing athletes, as the adaptation process of muscle-tendon unit is affected by both environmental mechanical stimuli and maturation. The present study investigated potential imbalances of knee extensor muscle strength and patellar tendon properties in adolescent compared with middle-aged athletes featuring long-term musculotendinous adaptations. Nineteen adolescent elite volleyball athletes [(A), 15.9 ± 0.6 years] and 18 middle-aged competitively active former elite volleyball athletes [(MA), 46.9 ± 0.6 years] participated in magnetic resonance imaging and ultrasound-dynamometry sessions to determine quadriceps femoris muscle strength, vastus lateralis morphology and patellar tendon mechanical and morphological properties. There was no significant age effect on the physiological cross-sectional area of the vastus lateralis and maximum knee extension moment (P > 0.05) during voluntary isometric contractions. However, the patellar tendon cross-sectional area was significantly smaller (A: 107.4 ± 27.5 mm(2) ; MA: 121.7 ± 39.8 mm(2) ) and the tendon stress during the maximal contractions was significantly higher in adolescent compared with the middle-aged athletes (A: 50.0 ± 10.1 MPa; MA: 40.0 ± 9.5 MPa). These findings provide evidence of an imbalanced development of muscle strength and tendon mechanical and morphological properties in adolescent athletes, which may have implications for the risk of tendon overuse injuries. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Mechanical properties of low tantalum alloys

    Science.gov (United States)

    Kortovich, C. S.

    1982-01-01

    The mechanical property behavior of equiaxed cast B-1900 + Hf alloy as a function of tantalum content was studied. Tensile and stress rupture characterization was conducted on cast to size test bars containing tantalum at the 4.3% (standard level), 2.2% and 0% levels. Casting parameters were selected to duplicate conditions used to prepare test specimens for master metal heat qualification. The mechanical property results as well as results of microstructural/phase analysis of failed test bars are presented.

  4. [Clinical application of peroneal muscles tendon transposition in repair of Achilles tendon rupture].

    Science.gov (United States)

    Jin, Rihao; Jin, Yu; Fang, Xiulin

    2006-07-01

    To discuss applied anatomy, biomechanics and surgical procedures of long peroneal muscles tendon transposition in repair of occlusive achilles tendon rupture. The blood supply and the morphology of long peroneal muscles tendon were observed in the lower extremity of 50 sides adult specimens and the mechanical tests which stretch load on the tendon were carried out. The methods were designed on the basis of the anatomical characteristics and morphology. Ten patients suffering occlusive Achilles tendon rupture were treated by using long peroneal muscles tendon transposition from March 2001 to July 2004. Among 10 patients, there were 7 males and 3 females, aging 32 to 54 years including 6 cases of jump injury, 2 cases of bruise, 1 case of step vacancy and 1 case of spontaneity injury. The interval between injury and surgery was 6 hours to 7 days in 7 fresh rupture and 21 days to 3 months in 3 old rupture. All cases belonged to occlusive Achilles tendon rupture (8 cases of complete rupture and 2 cases of incomplete rupture). The origin of long peroneal muscles was proximal tibia and fibular head, the end of them was base of first metatarsal bones and medial cuboid. The length of tendon was 13.5 +/- 2.5 cm. The width of origin tendon was 0.9 +/- 0.2 cm and the thickness was 0.3 +/- 0.1 cm; the width on apex of lateral malleolus was 0.7 +/- 0.1 cm and the thickness was 0.4 +/- 0.1 cm, the width on head of cuboid was 0.7 +/- 0.1 cm and the thickness was 0.3 +/- 0.1 cm. The long peroneal muscles tendon had abundant blood supply. The results of mechanical test showed that the biggest load was 2,292.4 +/- 617.3 N on tendon calcaneus, 1,020.4 +/- 175.4 N on long peroneal muscles tendon, 752.0 +/- 165.4 N on peroneus brevis tendon and 938.2 +/- 216.7 N on tibialis posterior tendon. Ten cases of occlusive Achilles tendon rupture achieved healing by first intention and were followed up 18-24 months. No Achilles tendon re-rupture, necrosis of skin or other complications occurred

  5. Tissue memory in healing tendons: short loading episodes stimulate healing.

    Science.gov (United States)

    Andersson, Therese; Eliasson, Pernilla; Aspenberg, Per

    2009-08-01

    Intact tendons adapt slowly to changes in mechanical loading, whereas in healing tendons the effect of mechanical loading or its absence is dramatic. The longevity of the response to a single loading episode is, however, unknown. We hypothesized that the tissue has a "memory" of loading episodes and that therefore short loadings are sufficient to elicit improved healing. The Achilles tendon of 70 female rats was transected and unloaded by tail suspension for 12 days (suspension started on day 2 after surgery). Each day, the rats were let down from suspension for short daily training episodes according to different regimes: 15 min of cage activity or treadmill running for 15, 30, 60, or 2x15 min. Rats with transected Achilles tendons and full-time cage activity served as controls. The results demonstrated that full-time cage activity increased the peak force over three times compared with unloading. Short daily loading episodes (treadmill running) increased the peak force about half as much as full-time activity. Prolongation of treadmill running above 15 min or dividing the daily training in two separate episodes had minimal further effect. This mechanical stimulation increased the cross-sectional area but had no effect on the mechanical properties of the repair tissue. The findings indicate that once the tissue had received information from a certain loading type and level, this is "memorized" and leads to a response lasting many hours. This suggests that patients might be allowed early short loading episodes following, e.g., an Achilles tendon rupture for a better outcome.

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

    Science.gov (United States)

    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 tendons and ligaments of the distal forelimb in horses. © 2013 American College of Veterinary Radiology.

  7. The microstructure and micromechanics of the tendon-bone insertion

    Science.gov (United States)

    Rossetti, L.; Kuntz, L. A.; Kunold, E.; Schock, J.; Müller, K. W.; Grabmayr, H.; Stolberg-Stolberg, J.; Pfeiffer, F.; Sieber, S. A.; Burgkart, R.; Bausch, A. R.

    2017-06-01

    The exceptional mechanical properties of the load-bearing connection of tendon to bone rely on an intricate interplay of its biomolecular composition, microstructure and micromechanics. Here we identify that the Achilles tendon-bone insertion is characterized by an interface region of ~500 μm with a distinct fibre organization and biomolecular composition. Within this region, we identify a heterogeneous mechanical response by micromechanical testing coupled with multiscale confocal microscopy. This leads to localized strains that can be larger than the remotely applied strain. The subset of fibres that sustain the majority of loading in the interface area changes with the angle of force application. Proteomic analysis detects enrichment of 22 proteins in the interfacial region that are predominantly involved in cartilage and skeletal development as well as proteoglycan metabolism. The presented mechanisms mark a guideline for further biomimetic strategies to rationally design hard-soft interfaces.

  8. Changes of Achilles tendon properties via 12-week PNF based robotic rehabilitation of ankle joints with spasticity and/or contracture.

    Science.gov (United States)

    Zhou, Zhihao; Zhou, Yuan; Wang, Ninghua; Gao, Fan; Wang, Long; Wei, Kunlin; Wang, Qining

    2014-01-01

    Ankle joint with spasticity and/or contracture can severely affect mobility and independence of stroke survivors. Due to that, the Achilles tendon(AT) is affected. In this paper, we aim to study changes of AT properties via proprioceptive neuromuscular facilitation (PNF) treatment. A robotic ankle-foot rehabilitation system has been proposed, which consists of a robotic ankle-foot platform and a graphic user interface. In this pilot study, two post-stroke patients participated and carried out a 12-week PNF treatment with the robotic system. The treatment is evaluated quantitatively in AT properties. The evaluation shows that after the PNF treatment, the average decrease of AT length is 4.1 mm (6.5%) and the recovery ratio is 30.4%, while the thickness has no change. The results indicate that the PNF based robotic rehabilitation for ankle joints with spasticity and/or contracture is effective to improve the ankle spasticity/contracture.

  9. Diseases of the tendons and tendon sheaths.

    Science.gov (United States)

    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. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Primary flexor tendon repair: surgical techniques based on the anatomy and biology of the flexor tendon system.

    Science.gov (United States)

    Tonkin, M A

    1991-01-01

    The anatomy, biology and bio-mechanics of the flexor tendon system demand a precise approach to flexor tendon repair. Within the fibroosseous canal, the synovial fluid and a complex intratendinous vascular network provide nutrition for intrinsic flexor tendon healing. Retention of the synovial sheath theoretically maintains an enclosed tendon/tendon sheat environment in which the tendon repair is bathed in synovial fluid, and may glide within a smooth tunnel. The preservation of the intricate double tendon inter-relationship and the annular pulley system is vital to the efficiency of finger flexion. This review details surgical and postoperative techniques aimed at restoring the normal anatomy and providing optimal conditions for the return of flexor tendon function.

  11. Anterior cruciate ligament- and hamstring tendon-derived cells: in vitro differential properties of cells involved in ACL reconstruction.

    Science.gov (United States)

    Ghebes, Corina Adriana; Kelder, Cindy; Schot, Thomas; Renard, Auke J; Pakvis, Dean F M; Fernandes, Hugo; Saris, Daniel B

    2017-04-01

    Anterior cruciate ligament (ACL) reconstruction involves the replacement of the torn ligament with a new graft, often a hamstring tendon (HT). Described as similar, the ACL and HT have intrinsic differences related to their distinct anatomical locations. From a cellular perspective, identifying these differences represents a step forward in the search for new cues that enhance recovery after the reconstruction. The purpose of this study was to characterize the phenotype and multilineage potential of ACL- and HT-derived cells. ACL- and HT-derived cells were isolated from tissue harvest from patients undergoing total knee arthroplasty (TKA) or ACL reconstruction. In total, three ACL and three HT donors were investigated. Cell morphology, self-renewal potential (CFU-F), surface marker profiling, expression of tendon/ligament-related markers (PCR) and multilineage potential were analysed for both cell types; both had fibroblast-like morphology and low self-renewal potential. No differences in the expression of tendon/ligament-related genes or a selected set of surface markers were observed between the two cell types. However, differences in their multilineage potential were observed: while ACL-derived cells showed a high potential to differentiate into chondrocytes and adipocytes, but not osteoblasts, HT-derived cells showed poor potential to form adipocytes, chondrocytes and osteoblasts. Our results demonstrated that HT-derived cells have low multilineage potential compared to ACL-derived cells, further highlighting the need for extrinsic signals to fully restore the function of the ACL upon reconstruction. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  12. Tendon Vasculature in Health and Disease

    Science.gov (United States)

    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

  13. A Biomechanical Study of a Novel Asymmetric 6-Strand Flexor Tendon Repair Using Porcine Tendons.

    Science.gov (United States)

    Wong, Yoke Rung; Tay, Shian Chao

    2018-01-01

    This study evaluated the biomechanical performance of a novel asymmetric 6-strand flexor tendon repair technique without locking loops. Twenty porcine flexor tendons were equally repaired by using the asymmetric technique and compared with the modified Lim-Tsai repair technique. The ultimate tensile strength, load to 1-mm gap force, stiffness, and mechanism of failure were measured. The asymmetric repair technique had significantly higher tensile strength (63.3 ± 3.7 N) than the modified Lim-Tsai repairs (46.7 ± 8.3 N). A novel flexor tendon repair technique with improved biomechanical performance may be available for use in flexor tendon repairs.

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

    Science.gov (United States)

    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. Copyright © 2013 Orthopaedic Research Society.

  15. Peroneal Tendon Injuries

    Science.gov (United States)

    ... the type of peroneal tendon injury. Options include: Immobilization. A cast or splint may be used to ... arthritis, gout, tendonitis, fracture, nerve compression (tarsal tunnel syndrome), infection and... Founded in 1942, the American College ...

  16. Chronic Achilles Tendon Rupture

    Science.gov (United States)

    Maffulli, Nicola; Via, Alessio Giai; Oliva, Francesco

    2017-01-01

    Background: The Achilles tendon, the largest and strongest tendon in the human body, is nevertheless one of the tendons which most commonly undergoes a complete subcutaneous tear. Achilles tendon ruptures are especially common in middle aged men who occasionally participate in sport. Even though Achilles tendon ruptures are frequent, up to 25% of acute injuries are misdiagnosed, and present as chronic injuries. Methods: This is a review article about diagnosis and management of chronic Achilles tendon ruptures. Minimally invasive Achilles tendon reconstruction is discussed. Results: The optimal surgical procedure is still debated, however, less invasive peroneus brevis reconstruction technique and free hamstring autograft provide good functional results. Conclusion: The management of chronic ruptures is more demanding than acute tears, because of the retraction of the tendon ends, and the gap makes primary repair impossible. Wound complications and infections are frequent after open procedures. Minimally invasive treatments provide good functional results and lower complications rate. PMID:29081863

  17. Tensile force transmission in human patellar tendon fascicles is not mediated by glycosaminoglycans

    DEFF Research Database (Denmark)

    Svensson, René B; Hassenkam, Tue; Hansen, Philip

    2011-01-01

    the mechanical properties of fascicles from human patellar tendon at two different deformation rates before and after removal of GAGs by treatment with chondroitinase ABC. Efficiency of enzyme treatment was quantified using dimethylmethylene blue assay. Removal of at least 79% of the GAGs did not significantly...

  18. Cell-material interactions in tendon tissue engineering.

    Science.gov (United States)

    Lin, Junxin; Zhou, Wenyan; Han, Shan; Bunpetch, Varitsara; Zhao, Kun; Liu, Chaozhong; Yin, Zi; Ouyang, Hongwei

    2018-01-31

    The interplay between cells and materials is a fundamental topic in biomaterial-based tissue regeneration. One of the principles for biomaterial development in tendon regeneration is to stimulate tenogenic differentiation of stem cells. To this end, efforts have been made to optimize the physicochemical and bio-mechanical properties of biomaterials for tendon tissue engineering. However, recent progress indicated that innate immune cells, especially macrophages, can also respond to the material cues and undergo phenotypical changes, which will either facilitate or hinder tissue regeneration. This process has been, to some extent, neglected by traditional strategies and may partially explain the unsatisfactory outcomes of previous studies; thus, more researchers have turned their focus on developing and designing immunoregenerative biomaterials to enhance tendon regeneration. In this review, we will first summarize the effects of material cues on tenogenic differentiation and paracrine secretion of stem cells. A brief introduction will also be made on how material cues can be manipulated for the regeneration of tendon-to-bone interface. Then, we will discuss the characteristics and influences of macrophages on the repair process of tendon healing and how they respond to different materials cues. These principles may benefit the development of novel biomaterials provided with combinative bioactive cues to activate tenogenic differentiation of stem cells and pro-resolving macrophage phenotype. The progress achieved with the rapid development of biomaterial-based strategies for tendon regeneration has not yielded broad benefits to clinical patients. In addition to the interplay between stem cells and biomaterials, the innate immune response to biomaterials also plays a determinant role in tissue regeneration. Here, we propose that fine-tuning of stem cell behaviors and alternative activation of macrophages through material cues may lead to effective tendon

  19. Biologics for tendon repair☆

    Science.gov (United States)

    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

  20. Hydrogen storage properties on mechanically milled graphite

    OpenAIRE

    Ichikawa, Takayuki; Chen, D. M.; Isobe, Shigehito; Gomibuchi, Emi; Fujii, Hironobu

    2004-01-01

    We investigated hydrogen absorption/desorption and structural properties in mechanically milled graphite under hydrogen pressures up to 6 MPa to clarify catalytic and hydrogen pressure effects in the milling. The results indicate that a small amount of iron contamination during milling plays a quite important role as a catalyst for hydrogen absorption/desorption properties in graphite. Two-peak structure for hydrogen desorption in the TDS profile is due to existence of two different occupatio...

  1. Mechanical Properties of Ingot Nb Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi; Dhakal, Pashupati; Kneisel, Peter; Mammosser, John; Matalevich, Joseph; Rao Myneni, Ganapati

    2014-07-01

    This contribution presents the results of measurements of the resonant frequency and of strain along the contour of a single-cell cavity made of ingot Nb subjected to increasing uniform differential pressure, up to 6 atm. The data were used to infer mechanical properties of this material after cavity fabrication, by comparison with the results from simulation calculations done with ANSYS. The objective is to provide useful information about the mechanical properties of ingot Nb cavities which can be used in the design phase of SRF cavities intended to be built with this material.

  2. MicroRNA29a Treatment Improves Early Tendon Injury.

    Science.gov (United States)

    Watts, Ashlee E; Millar, Neal L; Platt, Josh; Kitson, Susan M; Akbar, Moeed; Rech, Raquel; Griffin, Jay; Pool, Roy; Hughes, Tom; McInnes, Iain B; Gilchrist, Derek S

    2017-10-04

    Tendon injuries (tendinopathies) are common in human and equine athletes and characterized by dysregulated collagen matrix, resulting in tendon damage. We have previously demonstrated a functional role for microRNA29a (miR29a) as a post-transcriptional regulator of collagen 3 expression in murine and human tendon injury. Given the translational potential, we designed a randomized, blinded trial to evaluate the potential of a miR29a replacement therapy as a therapeutic option to treat tendinopathy in an equine model that closely mimics human disease. Tendon injury was induced in the superficial digital flexor tendon (SDFT) of 17 horses. Tendon lesions were treated 1 week later with an intralesional injection of miR29a or placebo. miR29a treatment reduced collagen 3 transcript levels at week 2, with no significant changes in collagen 1. The relative lesion cross-sectional area was significantly lower in miR29a tendons compared to control tendons. Histology scores were significantly better for miR29a-treated tendons compared to control tendons. These data support the mechanism of microRNA-mediated modulation of early pathophysiologic events that facilitate tissue remodeling in the tendon after injury and provides a strong proof of principle that a locally delivered miR29a therapy improves early tendon healing. Copyright © 2017 The American Society of Gene and Cell Therapy. All rights reserved.

  3. Autologous tendon-derived cell-seeded nanofibrous scaffolds improve rotator cuff repair in an age-dependent fashion.

    Science.gov (United States)

    Huegel, Julianne; Kim, Dong Hwa; Cirone, James M; Pardes, Adam M; Morris, Tyler R; Nuss, Courtney A; Mauck, Robert L; Soslowsky, Louis J; Kuntz, Andrew F

    2017-06-01

    Rotator cuff tendon tears are one of the most common shoulder pathologies, especially in the aging population. Due to a poor healing response and degenerative changes associated with aging, rotator cuff repair failure remains common. Although cell-based therapies to augment rotator cuff repair appear promising, it is unknown whether the success of such a therapy is age-dependent. We hypothesized that autologous cell therapy would improve tendon-to-bone healing across age groups, with autologous juvenile cells realizing the greatest benefit. In this study, juvenile, adult, and aged rats underwent bilateral supraspinatus tendon repair with augmentation of one shoulder with autologous tendon-derived cell-seeded polycaprolactone scaffolds. At 8 weeks, shoulders treated with cells in both juvenile and aged animals exhibited increased cellularity, increased collagen organization, and improved mechanical properties. No changes between treated and control limbs were seen in adult rats. These findings suggest that cell delivery during supraspinatus repair initiates earlier matrix remodeling in juvenile and aged animals. This may be due to the relative "equilibrium" of adult tendon tissue with regards to catabolic and anabolic processes, contrasted with actively growing juvenile tendons and degenerative aged tendons. This study demonstrates the potential for autologous cell-seeded scaffolds to improve repairs in both the juvenile and aged population. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1250-1257, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  4. The tendon of flexor pollicis longus: its effects on the muscular control of force and position at the human thumb.

    Science.gov (United States)

    Rack, P M; Ross, H F

    1984-06-01

    Human flexor pollicis longus tendons obtained at autopsy were subjected to repeated sinusoidal stretching movements. The associated force changes were almost in phase with the movement (force led position by less than 4 degrees), and alterations in the frequency of movement between 2 and 16 Hz had little effect on them. Examination of the thumbs of formalin-fixed cadavers demonstrated that the tendon exerts its force 7.4-8.0 mm in front of the axis of movement of the interphalangeal joint. From a knowledge of the tendon properties and the joint anatomy, one can calculate the changes in tendon length that would accompany any force change at the joint. Equipped with this information one can re-examine the responses to sinusoidal movements of the thumb interphalangeal joints of normal subjects. When the subject exerts a steady flexing force in which stretch reflexes play no important part, measurements of joint stiffness indicate that only a portion of the imposed movement reaches the muscle fibres. The extension of those (visco-elastic) muscle fibres lags behind the extension of the (elastic) tendon. Stretch reflexes contribute to the mechanical resistance of muscle fibres to low frequency (3-5 Hz) displacements, but in the presence of a compliant tendon the length of the muscle fibres does not determine the angle of the joint in any positive way. It is suggested that the compliant tendons of many thumb and finger muscles simplify the neuromuscular control of forces during gripping and handling movements.

  5. Targeted Deletion of Collagen V in Tendons and Ligaments Results in a Classic Ehlers-Danlos Syndrome Joint Phenotype

    Science.gov (United States)

    Sun, Mei; Connizzo, Brianne K.; Adams, Sheila M.; Freedman, Benjamin R.; Wenstrup, Richard J.; Soslowsky, Louis J.; Birk, David E.

    2016-01-01

    Collagen V mutations underlie classic Ehlers-Danlos syndrome, and joint hypermobility is an important clinical manifestation. We define the function of collagen V in tendons and ligaments, as well as the role of alterations in collagen V expression in the pathobiology in classic Ehlers-Danlos syndrome. A conditional Col5a1flox/flox mouse model was bred with Scleraxis-Cre mice to create a targeted tendon and ligament Col5a1-null mouse model, Col5a1Δten/Δten. Targeting was specific, resulting in collagen V–null tendons and ligaments. Col5a1Δten/Δten mice demonstrated decreased body size, grip weakness, abnormal gait, joint laxity, and early-onset osteoarthritis. These gross changes were associated with abnormal fiber organization, as well as altered collagen fibril structure with increased fibril diameters and decreased fibril number that was more severe in a major joint stabilizing ligament, the anterior cruciate ligament (ACL), than in the flexor digitorum longus tendon. The ACL also had a higher collagen V content than did the flexor digitorum longus tendon. The collagen V–null ACL and flexor digitorum longus tendon both had significant alterations in mechanical properties, with ACL exhibiting more severe changes. The data demonstrate critical differential regulatory roles for collagen V in tendon and ligament structure and function and suggest that collagen V regulatory dysfunction is associated with an abnormal joint phenotype, similar to the hypermobility phenotype in classic Ehlers-Danlos syndrome. PMID:25797646

  6. Development of a surgically optimized graft insertion suture technique to accommodate a tissue-engineered tendon in vivo.

    Science.gov (United States)

    Sawadkar, Prasad; Alexander, Susan; Tolk, Marten; Wong, Jason; McGrouther, Duncan; Bozec, Laurent; Mudera, Vivek

    2013-10-01

    The traumatic rupture of tendons is a common clinical problem. Tendon repair is surgically challenging because the tendon often retracts, resulting in a gap between the torn end and its bony insertion. Tendon grafts are currently used to fill this deficit but are associated with potential complications relating to donor site morbidity and graft necrosis. We have developed a highly reproducible, rapid process technique to manufacture compressed cell-seeded type I collagen constructs to replace tendon grafts. However, the material properties of the engineered constructs are currently unsuitable to withstand complete load bearing in vivo. A modified suture technique has been developed to withstand physiological loading and off load the artificial construct while integration occurs. Lapine tendons were used ex vivo to test the strength of different suture techniques with different sizes of Prolene sutures and tissue-engineered collagen constructs in situ. The data were compared to standard modified Kessler suture using a standard tendon graft. Mechanical testing was carried out and a finite element analysis stress distribution model constructed using COMSOL 3.5 software. The break point for modified suture technique with a tissue-engineered scaffold was significantly higher (50.62 N) compared to a standard modified Kessler suture (12.49 N, ptechnique is suitable for testing in vivo, and this will be the next stage of our research.

  7. Do cells contribute to tendon and ligament biomechanics?

    Directory of Open Access Journals (Sweden)

    Niels Hammer

    Full Text Available Acellular scaffolds are increasingly used for the surgical repair of tendon injury and ligament tears. Despite this increased use, very little data exist directly comparing acellular scaffolds and their native counterparts. Such a comparison would help establish the effectiveness of the acellularization procedure of human tissues. Furthermore, such a comparison would help estimate the influence of cells in ligament and tendon stability and give insight into the effects of acellularization on collagen.Eighteen human iliotibial tract samples were obtained from nine body donors. Nine samples were acellularized with sodium dodecyl sulphate (SDS, while nine counterparts from the same donors remained in the native condition. The ends of all samples were plastinated to minimize material slippage. Their water content was adjusted to 69%, using the osmotic stress technique to exclude water content-related alterations of the mechanical properties. Uniaxial tensile testing was performed to obtain the elastic modulus, ultimate stress and maximum strain. The effectiveness of the acellularization procedure was histologically verified by means of a DNA assay.The histology samples showed a complete removal of the cells, an extensive, yet incomplete removal of the DNA content and alterations to the extracellular collagen. Tensile properties of the tract samples such as elastic modulus and ultimate stress were unaffected by acellularization with the exception of maximum strain.The data indicate that cells influence the mechanical properties of ligaments and tendons in vitro to a negligible extent. Moreover, acellularization with SDS alters material properties to a minor extent, indicating that this method provides a biomechanical match in ligament and tendon reconstruction. However, the given protocol insufficiently removes DNA. This may increase the potential for transplant rejection when acellular tract scaffolds are used in soft tissue repair. Further research

  8. Mechanical properties of thermoelectric lanthanum telluride from quantum mechanics

    Science.gov (United States)

    Li, Guodong; Aydemir, Umut; Wood, Max; Goddard, William A., III; Zhai, Pengcheng; Zhang, Qingjie; Snyder, G. Jeffrey

    2017-07-01

    Lanthanum telluride (La3Te4) is an n-type high-performance thermoelectric material in the high temperature range, but its mechanical properties remain unknown. Since we want robust mechanical properties for their integration into industrial applications, we report here quantum mechanics (QM) simulations to determine the ideal strength and deformation mechanisms of La3Te4 under pure shear deformations. Among all plausible shear deformation paths, we find that shearing along the (0 0 1)/text{1} 0 0> slip system has the lowest ideal shear strength of 0.99 GPa, making it the most likely slip system to be activated under pressure. We find that the long range La-Te ionic interactions play the predominant role in resisting shear deformation. To enhance the mechanical strength, we suggest improving the long ionic La-Te bond stiffness to strengthen the ionic La-Te framework in La3Te4 by a defect-engineering strategy, such as partial substitution of La by Ce or Pr having isotypic crystal structures. This work provides the fundamental information to understand the intrinsic mechanics of La3Te4.

  9. Multi-Layer Electrospun Membrane Mimicking Tendon Sheath for Prevention of Tendon Adhesions

    Directory of Open Access Journals (Sweden)

    Shichao Jiang

    2015-03-01

    Full Text Available Defect of the tendon sheath after tendon injury is a main reason for tendon adhesions, but it is a daunting challenge for the biomimetic substitute of the tendon sheath after injury due to its multi-layer membrane-like structure and complex biologic functions. In this study, a multi-layer membrane with celecoxib-loaded poly(l-lactic acid-polyethylene glycol (PELA electrospun fibrous membrane as the outer layer, hyaluronic acid (HA gel as middle layer, and PELA electrospun fibrous membrane as the inner layer was designed. The anti-adhesion efficacy of this multi-layer membrane was compared with a single-layer use in rabbit flexor digitorum profundus tendon model. The surface morphology showed that both PELA fibers and celecoxib-loaded PELA fibers in multi-layer membrane were uniform in size, randomly arrayed, very porous, and smooth without beads. Multi-layer membrane group had fewer peritendinous adhesions and better gliding than the PELA membrane group and control group in gross and histological observation. The similar mechanical characteristic and collagen expression of tendon repair site in the three groups indicated that the multi-layer membrane did not impair tendon healing. Taken together, our results demonstrated that such a biomimetic multi-layer sheath could be used as a potential strategy in clinics for promoting tendon gliding and preventing adhesion without poor tendon healing.

  10. Imbalances in the Development of Muscle and Tendon as Risk Factor for Tendinopathies in Youth Athletes: A Review of Current Evidence and Concepts of Prevention

    Science.gov (United States)

    Mersmann, Falk; Bohm, Sebastian; Arampatzis, Adamantios

    2017-01-01

    Tendons feature the crucial role to transmit the forces exerted by the muscles to the skeleton. Thus, an increase of the force generating capacity of a muscle needs to go in line with a corresponding modulation of the mechanical properties of the associated tendon to avoid potential harm to the integrity of the tendinous tissue. However, as summarized in the present narrative review, muscle and tendon differ with regard to both the time course of adaptation to mechanical loading as well as the responsiveness to certain types of mechanical stimulation. Plyometric loading, for example, seems to be a more potent stimulus for muscle compared to tendon adaptation. In growing athletes, the increased levels of circulating sex hormones might additionally augment an imbalanced development of muscle strength and tendon mechanical properties, which could potentially relate to the increasing incidence of tendon overload injuries that has been indicated for adolescence. In fact, increased tendon stress and strain due to a non-uniform musculotendinous development has been observed recently in adolescent volleyball athletes, a high-risk group for tendinopathy. These findings highlight the importance to deepen the current understanding of the interaction of loading and maturation and demonstrate the need for the development of preventive strategies. Therefore, this review concludes with an evidence-based concept for a specific loading program for increasing tendon stiffness, which could be implemented in the training regimen of young athletes at risk for tendinopathy. This program incorporates five sets of four contractions with an intensity of 85–90% of the isometric voluntary maximum and a movement/contraction duration that provides 3 s of high magnitude tendon strain. PMID:29249987

  11. Imbalances in the Development of Muscle and Tendon as Risk Factor for Tendinopathies in Youth Athletes: A Review of Current Evidence and Concepts of Prevention

    Directory of Open Access Journals (Sweden)

    Falk Mersmann

    2017-12-01

    Full Text Available Tendons feature the crucial role to transmit the forces exerted by the muscles to the skeleton. Thus, an increase of the force generating capacity of a muscle needs to go in line with a corresponding modulation of the mechanical properties of the associated tendon to avoid potential harm to the integrity of the tendinous tissue. However, as summarized in the present narrative review, muscle and tendon differ with regard to both the time course of adaptation to mechanical loading as well as the responsiveness to certain types of mechanical stimulation. Plyometric loading, for example, seems to be a more potent stimulus for muscle compared to tendon adaptation. In growing athletes, the increased levels of circulating sex hormones might additionally augment an imbalanced development of muscle strength and tendon mechanical properties, which could potentially relate to the increasing incidence of tendon overload injuries that has been indicated for adolescence. In fact, increased tendon stress and strain due to a non-uniform musculotendinous development has been observed recently in adolescent volleyball athletes, a high-risk group for tendinopathy. These findings highlight the importance to deepen the current understanding of the interaction of loading and maturation and demonstrate the need for the development of preventive strategies. Therefore, this review concludes with an evidence-based concept for a specific loading program for increasing tendon stiffness, which could be implemented in the training regimen of young athletes at risk for tendinopathy. This program incorporates five sets of four contractions with an intensity of 85–90% of the isometric voluntary maximum and a movement/contraction duration that provides 3 s of high magnitude tendon strain.

  12. Mechanical properties of wet granular materials

    NARCIS (Netherlands)

    Fournier, Z.; Geromichalos, D.; Herminghaus, S.; Kohonen, M.M.; Mugele, Friedrich Gunther; Scheel, M.; Schulz, M.

    2005-01-01

    We elaborate on the impact of liquids upon the mechanical properties of granular materials. We find that most of the experimental and simulation results may be accounted for by a simple model assuming frictionless, spherical grains, with a hysteretic attractive interaction between neighbouring

  13. Improving mechanical properties of aluminium alloy through ...

    African Journals Online (AJOL)

    This paper investigates the microstructure and mechanical properties of aluminum alloy (Al-Si-Fe) reinforced with coconut shell-ash particulate. The aluminium (Al-Si-Fe) alloy composite was produced by a double-stir casting process at a speed of 700 rpm for 10 and 5 minutes at first and second stirring respectively.

  14. Material, compressional and mechanical properties of Borassus ...

    African Journals Online (AJOL)

    The compressional and mechanical properties of tablet formulations incorporating native and modified Borassus aethiopum starches as binder were evaluated. The native Borassus aethiopum starch (BAS) was modified to yield fully gelatinised starch (FGBAS) and microcrystalline starch (MBAS). The compressional ...

  15. Mechanical properties of glass polymer multilayer composite

    Indian Academy of Sciences (India)

    Unknown

    Mechanical properties of glass polymer multilayer composite. A SEAL, N R BOSE, S K DALUI, A K MUKHOPADHYAY*, K K PHANI and. H S MAITI. Central Glass and Ceramic Research Institute, Kolkata 700 032, India. Abstract. The preliminary experimental studies on the comparative behaviour of the deformation ...

  16. Tuning the mechanical properties of silica microcapsules

    NARCIS (Netherlands)

    Zhang, L.; D'Acunzi, M.; Kappl, M.; Imhof, A.; van Blaaderen, A.; Butt, H. -J; Graf, R.; Vollmer, D.

    2010-01-01

    Heat treatment is a standard method to increase the hardness of silica in various applications. Here, we tested the effect of high temperature annealing on the mechanical properties of silica microcapsules by force spectroscopy under point loads applied to the particle shell. The Young's modulus of

  17. Thermal, electrochemical and mechanical properties of shape ...

    African Journals Online (AJOL)

    ... resemblance with structure of casted shape memory alloy obtained from the vacuum induction process. The Vickers hardness test was also performed. Quenched microstructure with improved hardness than pre-quenched structure was observed. Keywords: Shape Memory Alloy, Microstructure, Mechanical Properties ...

  18. Synthesis, mechanical, thermal and chemical properties of ...

    Indian Academy of Sciences (India)

    Unknown

    Department of Chemistry, Manonmaniam Sundaranar University, Abishekapatti, Tirunelveli 627 012, India. MS received 28 August 2003; ... thanes were characterized with respect to their resistance to chemical reagents and mechanical properties such as tensile strength, ..... Recent advances (ed.) I S. Bhardwajj (New ...

  19. Nanostructured thin films and coatings mechanical properties

    CERN Document Server

    2010-01-01

    The first volume in "The Handbook of Nanostructured Thin Films and Coatings" set, this book concentrates on the mechanical properties, such as hardness, toughness, and adhesion, of thin films and coatings. It discusses processing, properties, and performance and provides a detailed analysis of theories and size effects. The book presents the fundamentals of hard and superhard nanocomposites and heterostructures, assesses fracture toughness and interfacial adhesion strength of thin films and hard nanocomposite coatings, and covers the processing and mechanical properties of hybrid sol-gel-derived nanocomposite coatings. It also uses nanomechanics to optimize coatings for cutting tools and explores various other coatings, such as diamond, metal-containing amorphous carbon nanostructured, and transition metal nitride-based nanolayered multilayer coatings.

  20. Mechanical Properties of Tyramine Substituted-Hyaluronan Enriched Fascia Extracellular Matrix

    Science.gov (United States)

    Chin, LiKang; Calabro, Anthony; Walker, Esteban; Derwin, Kathleen A.

    2011-01-01

    Naturally-occurring biomaterial scaffolds derived from extracellular matrix (ECM) have been the topic of recent investigation in the context of rotator cuff tendon repair. We previously reported a method to treat fascia ECM with high molecular weight tyramine substituted-hyaluronan (TS-HA) for use as a tendon augmentation scaffold. The presence of cross-linked TS-HA in fascia was associated with an increased macrophage and giant cell response compared to water treated controls after implantation in a rat abdominal wall model. The objective of this study was to determine the extent to which TS-HA treatment was associated with mechanical property changes of fascia after implantation in the rat model. Fascia samples in all groups demonstrated time-dependent decreases in mechanical properties. TS-HA treated fascia with cross-linking exhibited a lower toe modulus, a trend toward lower toe stiffness, and a higher transition strain than water treated controls not only after implantation, but also at time zero. TS-HA treatment, with or without cross-linking, had no significant effect on time-zero or post-implantation load relaxation ratio, load relaxation rate, linear-region stiffness, or linear-region modulus. Our findings demonstrated that the particular TS-HA treatment employed in this study decreased the low-load elastic mechanical properties of fascia ECM, in keeping with the heightened macrophage and giant cell host response seen previously. This work provides a starting point and guidance for investigating alternative HA treatment strategies. PMID:22238019

  1. Isotropic microscale mechanical properties of coral skeletons.

    Science.gov (United States)

    Pasquini, Luca; Molinari, Alan; Fantazzini, Paola; Dauphen, Yannicke; Cuif, Jean-Pierre; Levy, Oren; Dubinsky, Zvy; Caroselli, Erik; Prada, Fiorella; Goffredo, Stefano; Di Giosia, Matteo; Reggi, Michela; Falini, Giuseppe

    2015-05-06

    Scleractinian corals are a major source of biogenic calcium carbonate, yet the relationship between their skeletal microstructure and mechanical properties has been scarcely studied. In this work, the skeletons of two coral species:solitary Balanophyllia europaea and colonial Stylophora pistillata, were investigated by nanoindentation. The hardness HIT and Young's modulus E(IT) were determined from the analysis of several load-depth data on two perpendicular sections of the skeletons: longitudinal (parallel to the main growth axis) and transverse. Within the experimental and statistical uncertainty,the average values of the mechanical parameters are independent on the section's orientation. The hydration state of the skeletons did not affect the mechanical properties. The measured values, EIT in the 76-77 GPa range, and H(IT) in the 4.9–5.1 GPa range, are close to the ones expected for polycrystalline pure aragonite. Notably, a small difference in H(IT) is observed between the species. Different from corals, single-crystal aragonite and the nacreous layer of the seashell Atrina rigida exhibit clearly orientation-dependent mechanical properties. The homogeneous and isotropic mechanical behaviour of the coral skeletons at the microscale is correlated with the microstructure,observed by electron microscopy and atomic force microscopy, and with the X-ray diffraction patterns of the longitudinal and transverse sections.

  2. Mechanical Properties Of Traditional And Nanofibre Textiles

    Directory of Open Access Journals (Sweden)

    Ursíny Petr

    2015-09-01

    Full Text Available This study deals with a comparison of mechanical properties of a conventional yarn and a textile from nanofibres. The conventional yarn represents the textile objects with high degree of orientation of fibres and the textile from nanofibres represents the textile objects with low degree of orientation of fibres. The theoretical section is concerned with the issue of internal structure of plied yarn and resulting differences in the orientation and straightening of fibres and in utilisation of deformation properties of fibres in comparison to the referred nano textile. The experimental section describes the manner of realisation of both static and dynamic tests of conventional yarn and strips of nanofibres. The results show differences in the mechanical properties of conventional yarn and textile strip from nanofibres under static and dynamic loading conditions. The processing technology of conventional yarn has been verified in the long term. But textiles from nanofibres are a relatively new material and mechanical properties of the detected differences point out possible problems with their behaviour during standard technological processes.

  3. Effect of in vitro passaging on the stem cell-related properties of tendon-derived stem cells-implications in tissue engineering.

    Science.gov (United States)

    Tan, Qi; Lui, Pauline Po Yee; Rui, Yun Feng

    2012-03-20

    This study aimed to compare clonogenicity, proliferation, stem cell-related marker expression, senescence, and differentiation potential of rat patellar tendon-derived stem cells (TDSCs) at early (P5), mid (P10), and late (P20, P30) passages. The clonogenicity of the cells was assessed by colony-forming assay and their proliferative potential was assessed by bromodeoxyuridine assay. The surface expression of CD90 and CD73 was assessed by flow cytometry. The cellular senescence was assessed by β-galactosidase activity. The adipogenic, chondrogenic, and osteogenic differentiation potentials of TDSCs were assessed by standard assays after induction. The mRNA expression of tendon-related markers, scleraxis (Scx) and tenomodulin (Tnmd), was measured by quantitative real-time reverse transcription-polymerase chain reaction. Both the colony numbers and proliferative potential of TDSCs increased with passaging. Concomitantly, there was significant upregulation of β-galactosidase activity with TDSC passaging. The subculture of TDSCs downregulated the expression of CD90 and CD73. Lipid droplets were formed in the early and mid passages of TDSCs upon adipogenic induction, but were absent in the late passages. The expression of peroxisome proliferator activator receptor gamma 2 (PPARγ2) and CCAAT/enhancer binding protein alpha (C/EBPα) in TDSCs after adipogenic induction decreased with passaging. Chondrogenesis, proteoglycan deposition, collagen type II protein expression, collagen type 2A1 (Col2AI), and aggrecan (Acan) mRNA expression were less in pellets formed with later passages of TDSCs after chondrogenic induction. The expression of Scx and Tnmd was lower in the late, compared with early and mid, passages of TDSCs. However, matrix mineralization and expression of alkaline phosphatase (Alpl) and osteocalcin (Bglap) mRNA after osteogenic induction increased with TDSC passaging. Researchers and clinicians should consider the changes of stem cell-related properties of

  4. Study on mechanical properties after laser forming

    Science.gov (United States)

    Shen, Hong; Yao, Zhenqiang

    2009-01-01

    Laser forming is a means of processing materials in a novel manner. The mechanical properties of specimens after laser forming are investigated. By tension tests, the tension properties are analyzed to establish Ramberg-Osgood constitutive equations under different laser processing parameters. Experimental data show that the yield strength and tensile strength are improved after laser forming, while the elongation percentage is reduced. Based on the distribution of residual stresses as well as residual strains after the laser forming process, the fatigue life under different laser processing parameters is studied using low-cycle fatigue tests. The residual compressive plastic strain is the most important reason for improving the fatigue life of low carbon steel after laser forming. The fatigue fracture mechanism is shown through the analysis of macro-fracture and micro-fracture using the scanning electronic microscope.

  5. New approach of eggshell mechanical properties determinantion

    Directory of Open Access Journals (Sweden)

    Libor Severa

    2010-01-01

    Full Text Available The paper describes a new approach for determination of mechanical properties of hen’s eggshell. The suitability and applicability of a Berkovich indentation is discussed. The eggshells were tested in the area surrounding equator line. The deformation modes active during indentation have been examinined from the shape of load-displacement curves. According to measured dependencies, the eggshel shown an viscous-elastic deformation.The values of Young’s modulus E obtained from radial and tangential directions did not vary significantly. This fact shows on isotropic nature of eggshell structure. It was found that values of E do not significantly change neither around the cir­cum­fe­ren­ce of the equator. The values obtained within this research correspond to values reported in literature and obtained on macroscopic samples. Nanoindentation was found to be a precise and powerful tool, suitable for determining local variations of mechanical properties of eggshells.

  6. Isotropic microscale mechanical properties of coral skeletons

    OpenAIRE

    Pasquini, Luca; Molinari, Alan; Fantazzini, Paola; Dauphen, Yannicke; Cuif, Jean-Pierre; Levy, Oren; Dubinsky, Zvy; Caroselli, Erik; Prada, Fiorella; Goffredo, Stefano; Di Giosia, Matteo; Reggi, Michela; Falini, Giuseppe

    2015-01-01

    Scleractinian corals are a major source of biogenic calcium carbonate, yet the relationship between their skeletal microstructure and mechanical properties has been scarcely studied. In this work, the skeletons of two coral species: solitary Balanophyllia europaea and colonial Stylophora pistillata, were investigated by nanoindentation. The hardness HIT and Young's modulus EIT were determined from the analysis of several load–depth data on two perpendicular sections of the skeletons: longitud...

  7. Mechanical Properties of Additively Manufactured Thick Honeycombs

    Science.gov (United States)

    Hedayati, Reza; Sadighi, Mojtaba; Mohammadi Aghdam, Mohammad; Zadpoor, Amir Abbas

    2016-01-01

    Honeycombs resemble the structure of a number of natural and biological materials such as cancellous bone, wood, and cork. Thick honeycomb could be also used for energy absorption applications. Moreover, studying the mechanical behavior of honeycombs under in-plane loading could help understanding the mechanical behavior of more complex 3D tessellated structures such as porous biomaterials. In this paper, we study the mechanical behavior of thick honeycombs made using additive manufacturing techniques that allow for fabrication of honeycombs with arbitrary and precisely controlled thickness. Thick honeycombs with different wall thicknesses were produced from polylactic acid (PLA) using fused deposition modelling, i.e., an additive manufacturing technique. The samples were mechanically tested in-plane under compression to determine their mechanical properties. We also obtained exact analytical solutions for the stiffness matrix of thick hexagonal honeycombs using both Euler-Bernoulli and Timoshenko beam theories. The stiffness matrix was then used to derive analytical relationships that describe the elastic modulus, yield stress, and Poisson’s ratio of thick honeycombs. Finite element models were also built for computational analysis of the mechanical behavior of thick honeycombs under compression. The mechanical properties obtained using our analytical relationships were compared with experimental observations and computational results as well as with analytical solutions available in the literature. It was found that the analytical solutions presented here are in good agreement with experimental and computational results even for very thick honeycombs, whereas the analytical solutions available in the literature show a large deviation from experimental observation, computational results, and our analytical solutions. PMID:28773735

  8. Metrenperone enhances collagen turnover and remodeling in the early stages of healing of tendon injury in rabbit.

    Science.gov (United States)

    Oryan, Ahmad; Silver, Ian A; Goodship, Allen E

    2010-12-01

    This study evaluated the effects of metrenperone on healing of unilateral, collagenase-induced lesions in the Superficial Digital Flexor Tendons (SDFT) of rabbits. After controlled injury of the left SDFT, nine rabbits received daily treatment with metrenperone for 28 days. Another nine were untreated controls; in both groups the contra-lateral tendons served as uninjured controls. Histological and ultrastructural changes, mechanical properties, dry weight, collagen content, and amount of DNA in healing and control tendons were assessed 28 days after injury. Restoration of structural hierarchy was more organized in treated than in untreated tendons while cellularity was greater in the latter. At the ultrastructural level, collagen in treated lesions was predominantly in the form of small-diameter, new fibrils, with few large, old fibrils; in untreated lesions there was a high proportion of large, old fibrils but relatively few small, new ones. The amount of DNA in untreated injuries was much greater than in normal tendons, while in treated lesions it was not significantly different from that of uninjured controls. There were no significant differences in total collagen, stiffness and ultimate strength of injured, treated, and untreated tendons 28 days after injury. Both were significantly weaker than their corresponding contralaterals. The findings suggest that metrenperone had positive effects on collagen turnover, remodelling, and organization during acute inflammation and fibroplasia. Provided that the new fibrils subsequently matured in a normal manner, mechanical characteristics of the organized scar should be better than those of an untreated lesion.

  9. Basic mechanical properties of layered steels

    Directory of Open Access Journals (Sweden)

    Michal Černý

    2013-01-01

    Full Text Available This article deals with identifying attributes of layered steel materials (damask steel with the help of mechanical tests. Experimentally verify basic mechanical properties of layered steel and subsequently assessed it in comparison with the values obtained for the classic steel materials. In conclusion, there are listed the possibilities of using multilayer steel materials in technical practice, depending on the economics of production.The damask steel was prepared by forge welding from a packet consisting of 17 layers (9 layers of tool steel 19 133 (ČSN with the thickness of 6 mm and 8 layers 80NiCr11 steel in the form of saw bands with the thickness of 1.2 mm. The packet was cut into 8 parts, folded 3 times and forged together, which provided damask steel with 136 layers. The resulting steel bars were used to make semi-finished products with the approximate dimensions of the test specimens. For evaluation of mechanical properties were applied the following tests: tensile test, Charpy impact test, hardness and microhardness measurementsThe results of tests proved that the properties of damask steel are dependent not only on the direction led impact quality forge weld layers and content iof nhomogeneities in the place of discord, but also on the quenching and tempering temperature, resp. on the choice of quenching bath, which determine the final structure of steel and the resulting hardness, respectively microhardness.

  10. Effects of fibre orientation on mechanical properties of hybrid ...

    Indian Academy of Sciences (India)

    Administrator

    ° and ± 45° was used and its effect on mechanical properties were studied. Composites containing hybrid fibres found to possess better mechanical properties, when compared to pure bamboo. In order to justify this, the following mechanical.

  11. Measuring Mechanical Properties Of Optical Glasses

    Science.gov (United States)

    Tucker, Dennis S.; Nichols, Ronald L.

    1989-01-01

    Report discusses mechanical tests measuring parameters of strength and fracture mechanics of optical glasses. To obtain required tables of mechanical properties of each glass of interest, both initial-strength and delayed-fracture techniques used. Modulus of rupture measured by well-known four-point bending method. Initial bending strength measured by lesser-known double-ring method, in which disk of glass supported on one face near edge by larger ring and pressed on its other face by smaller concentric ring. Method maximizes stress near center, making it more likely specimen fractures there, and thereby suppresses edge effects. Data from tests used to predict reliabilities and lifetimes of glass optical components of several proposed spaceborne instruments.

  12. Mechanical Properties of Nanofilled Polypropylene Composites

    Directory of Open Access Journals (Sweden)

    Cristina-Elisabeta PELIN

    2015-06-01

    Full Text Available The paper presents a study concerning mechanical performance of thermoplastic nanocomposites based on isotactic polypropylene matrix, nanofilled with montmorillonite modified with quaternary ammonium salt and carboxyl functionalized carbon nanotubes, respectively, added in the same concentration relative to the matrix. The nanofilled and single polymer materials were obtained by simple melt compounding through extrusion process followed by injection molding into specific shape specimens for mechanical testing of the samples. Mechanical properties were evaluated by tensile and 3 point bending tests. In terms of modulus of elasticity, the results showed overall positive effects concerning the effect of nanofiller addition to the thermoplastic polymer. The fracture cross section of the tested specimens was characterized by FT-IR spectroscopy and SEM microscopy.

  13. Three-dimensional muscle-tendon geometry after rectus femoris tendon transfer.

    Science.gov (United States)

    Asakawa, Deanna S; Blemker, Silvia S; Rab, George T; Bagley, Anita; Delp, Scott L

    2004-02-01

    Rectus femoris tendon transfer is performed in patients with cerebral palsy to improve knee flexion during walking. This procedure involves detachment of the muscle from its insertion into the quadriceps tendon and reattachment to one of the knee flexor muscles. The purpose of the present study was to evaluate the muscle-tendon geometry and to assess the formation of scar tissue between the rectus femoris and adjacent structures. Magnetic resonance images of the lower extremities were acquired from five subjects after bilateral rectus femoris tendon transfer. A three-dimensional computer model of the musculoskeletal geometry of each of the ten limbs was created from these images. The three-dimensional paths of the rectus femoris muscles after transfer demonstrated that the muscle does not follow a straight course from its origin to its new insertion. The typical muscle-tendon path included an angular deviation; this deviation was sharp (>35 degrees ) in seven extremities. In addition, scar tissue between the transferred rectus femoris and the underlying muscles was visible on the magnetic resonance images. The angular deviations in the rectus femoris muscle-tendon path and the presence of scar tissue between the rectus femoris and the underlying muscles suggest that the beneficial effects of rectus femoris tendon transfer are derived from reducing the effects of the rectus femoris muscle as a knee extensor rather than from converting the muscle to a knee flexor. These findings clarify our understanding of the mechanism by which rectus femoris tendon transfer improves knee flexion.

  14. Percutaneous Achilles Tendon Lengthening

    Science.gov (United States)

    ... Ligament Reconstruction Lateral Ankle Stabilization Mosaicplasty for Osteochondral Lesions of the Talus Peroneus Longus to Achilles Tendon Transfer Pilon Fracture Surgery Posterior Ankle Endoscopy or ...

  15. Tendon and ligament imaging

    Science.gov (United States)

    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

  16. Patellar tendon adaptation in relation to load-intensity and contraction type

    DEFF Research Database (Denmark)

    Malliaras, Peter; Kamal, Beenish; Nowell, Alastair

    2013-01-01

    of contraction type and load-intensity on patellar tendon mechanical properties. METHOD: Load intensity was determined using the 1 repetition maximum (RM) on a resistance exercise device at baseline and fortnightly intervals in four randomly allocated groups of healthy, young males: (1) control (no training); (2......BACKGROUND: Loading leads to tendon adaptation but the influence of load-intensity and contraction type is unclear. Clinicians need to be aware of the type and intensity of loading required for tendon adaptation when prescribing exercise. The aim of this study was to investigate the influence......) concentric (80% of concentric-eccentric 1RM, 4×7-8); (3) standard load eccentric only (80% of concentric-eccentric 1RM, 4×12-15 repetitions) and (4) high load eccentric (80% of eccentric 1RM, 4×7-8 repetitions). Participants exercised three times a week for 12 weeks on a leg extension machine. Knee extension...

  17. Development of high shrinkage polyethylene terephthalate (PET) shape memory polymer tendons for concrete crack closure

    Science.gov (United States)

    Teall, Oliver; Pilegis, Martins; Sweeney, John; Gough, Tim; Thompson, Glen; Jefferson, Anthony; Lark, Robert; Gardner, Diane

    2017-04-01

    The shrinkage force exerted by restrained shape memory polymers (SMPs) can potentially be used to close cracks in structural concrete. This paper describes the physical processing and experimental work undertaken to develop high shrinkage die-drawn polyethylene terephthalate (PET) SMP tendons for use within a crack closure system. The extrusion and die-drawing procedure used to manufacture a series of PET tendon samples is described. The results from a set of restrained shrinkage tests, undertaken at differing activation temperatures, are also presented along with the mechanical properties of the most promising samples. The stress developed within the tendons is found to be related to the activation temperature, the cross-sectional area and to the draw rate used during manufacture. Comparisons with commercially-available PET strip samples used in previous research are made, demonstrating an increase in restrained shrinkage stress by a factor of two for manufactured PET filament samples.

  18. Mechanical Properties of Nylon Harp Strings

    Directory of Open Access Journals (Sweden)

    Nicolas Lynch-Aird

    2017-05-01

    Full Text Available Monofilament nylon strings with a range of diameters, commercially marketed as harp strings, have been tested to establish their long-term mechanical properties. Once a string had settled into a desired stress state, the Young’s modulus was measured by a variety of methods that probe different time-scales. The modulus was found to be a strong function of testing frequency and also a strong function of stress. Strings were also subjected to cyclical variations of temperature, allowing various thermal properties to be measured: the coefficient of linear thermal expansion and the thermal sensitivities of tuning, Young’s modulus and density. The results revealed that the particular strings tested are divided into two groups with very different properties: stress-strain behaviour differing by a factor of two and some parametric sensitivities even having the opposite sign. Within each group, correlation studies allowed simple functional fits to be found to the key properties, which have the potential to be used in automated tuning systems for harp strings.

  19. Unique mechanical properties of nanostructured metals.

    Science.gov (United States)

    Tsuji, Nobuhiro

    2007-11-01

    Recently, it becomes possible to fabricate bulk metals having ultrafine grained or nanocrystalline structures of which grain size is in nano-meter dimensions. One of the promising ways to realize bulk nanostructured metals is severe plastic deformation (SPD) above logarithmic equivalent strain of 4. We have developed an original SPD process, named Accumulative Roll Bonding (ARB) using rolling deformation in principle, and have succeeded in fabricating bulk nanostructured sheets of various kinds of metals and alloys. The ARB process and the nanostructured metals fabricated by the ARB are introduced in this paper. The nanostructured metals sometimes perform quite unique mechanical properties, that is rather surprising compared with conventionally coarse grained materials. The unique properties seem to be attributed to the characteristic structures of the nano-metals full of grain boundaries.

  20. PICA Variants with Improved Mechanical Properties

    Science.gov (United States)

    Thornton, Jeremy; Ghandehari, Ehson M.; Fan, Wenhong; Stackpoole, Margaret; Chavez-Garcia, Jose

    2011-01-01

    Phenolic Impregnated Carbon Ablator (PICA) is a member of the family of Lightweight Ceramic Ablators (LCAs) and was developed at NASA Ames Research Center as a thermal protection system (TPS) material for the Stardust mission probe that entered the Earth s atmosphere faster than any other probe or vehicle to date. PICA, carbon fiberform base and phenolic polymer, shows excellent thermal insulative properties at heating rates from about 250 W/sq cm to 1000 W/sq cm. The density of standard PICA - 0.26 g/cu cm to 0.28 g/cu cm - can be changed by changing the concentration of the phenolic resin. By adding polymers to the phenolic resin before curing it is possible to significantly improve the mechanical properties of PICA without significantly increasing the density.

  1. Characterization of mechanical properties of Inconel alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Soon Hyung; Kim, Hee Young; Sohn, Woong Hee; Ahn, Young Chul [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1997-07-01

    The microstructure and mechanical properties of Inconel 60 and Inconel 690 steam generator tube test-produced by Sammi Steel Co. Ltd. were analyzed to develop the Inconel steam generator tube for nuclear power plant. 2. The mechanical properties such as yield strength, tensile strength and elongation= satisfied the requirement of Combustion Engineering specification, but the yield strength is needed to be decreased. The effect of the carbon content on the mechanical properties in the range of 0.019-0.030 % were not observed. The effects of grain size on the yield strength and tensile strength were well agreed with Hall-Petch relationship. the creep rupture life of Inconel 690 were almost same in, and it is similar to the Inconel 690 first test-produced by Sammi Steel Co., Ltd. It was suggested that the master curve which could be predict the creep life with varying the temperature and stress from Larson-Miller parameter. The stress exponents were measured as 4 and the activation energy for creep were similar to the activation energy for self diffusion of self diffusion. It is analyzed that the creep deformation of Inconel 690 alloy were controlled by the dislocation climb. The solution temperature of carbides precipitates was measured in Inconel 600 and Inconel 690 and the optimum annealing temperature and time to obtain required grain size were suggested. The grain boundary carbides could be controlled by thermal treatment at 700 deg C. The serrations of stress were observed at temperature ranged 300-600 deg C in the stress strain curves. The strain rate sensitivities exhibited the negative value in the serrated region. The temperature range of Inconel 690 showing the serration in stress strain curve is higher than that of Inconel 600 about 50 deg C. (Author) 45 refs., 8 tabs., 33 figs.

  2. Decellularized and Engineered Tendons as Biological Substitutes: A Critical Review

    Directory of Open Access Journals (Sweden)

    Arianna B. Lovati

    2016-01-01

    Full Text Available 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.

  3. Composition and structure of porcine digital flexor tendon-bone insertion tissues.

    Science.gov (United States)

    Chandrasekaran, Sandhya; Pankow, Mark; Peters, Kara; Huang, Hsiao-Ying Shadow

    2017-11-01

    Tendon-bone insertion is a functionally graded tissue, transitioning from 200 MPa tensile modulus at the tendon end to 20 GPa tensile modulus at the bone, across just a few hundred micrometers. In this study, we examine the porcine digital flexor tendon insertion tissue to provide a quantitative description of its collagen orientation and mineral concentration by using Fast Fourier Transform (FFT) based image analysis and mass spectrometry, respectively. Histological results revealed uniformity in global collagen orientation at all depths, indicative of mechanical anisotropy, although at mid-depth, the highest fiber density, least amount of dispersion, and least cellular circularity were evident. Collagen orientation distribution obtained through 2D FFT of histological imaging data from fluorescent microscopy agreed with past measurements based on polarized light microscopy. Results revealed global fiber orientation across the tendon-bone insertion to be preserved along direction of physiologic tension. Gradation in the fiber distribution orientation index across the insertion was reflective of a decrease in anisotropy from the tendon to the bone. We provided elemental maps across the fibrocartilage for its organic and inorganic constituents through time-of-flight secondary ion mass spectrometry (TOF-SIMS). The apatite intensity distribution from the tendon to bone was shown to follow a linear trend, supporting past results based on Raman microprobe analysis. The merit of this study lies in the image-based simplified approach to fiber distribution quantification and in the high spatial resolution of the compositional analysis. In conjunction with the mechanical properties of the insertion tissue, fiber, and mineral distribution results for the insertion from this may potentially be incorporated into the development of a structural constitutive approach toward computational modeling. Characterizing the properties of the native insertion tissue would provide the

  4. Linking properties to microstructure through multiresolution mechanics

    Science.gov (United States)

    McVeigh, Cahal James

    The macroscale mechanical and physical properties of materials are inherently linked to the underlying microstructure. Traditional continuum mechanics theories have focused on approximating the heterogeneous microstructure as a continuum, which is conducive to a partial differential equation mathematical description. Although this makes large scale simulation of material much more efficient than modeling the detailed microstructure, the relationship between microstructure and macroscale properties becomes unclear. In order to perform computational materials design, material models must clearly relate the key underlying microstructural parameters (cause) to macroscale properties (effect). In this thesis, microstructure evolution and instability events are related to macroscale mechanical properties through a new multiresolution continuum analysis approach. The multiresolution nature of this theory allows prediction of the evolving magnitude and scale of deformation as a direct function of the changing microstructure. This is achieved via a two-pronged approach: (a) Constitutive models which track evolving microstructure are developed and calibrated to direct numerical simulations (DNS) of the microstructure. (b) The conventional homogenized continuum equations of motion are extended via a virtual power approach to include extra coupled microscale stresses and stress couples which are active at each characteristic length scale within the microstructure. The multiresolution approach is applied to model the fracture toughness of a cemented carbide, failure of a steel alloy under quasi-static loading conditions and the initiation and velocity of adiabatic shear bands under high speed dynamic loading. In each case the multiresolution analysis predicts the important scale effects which control the macroscale material response. The strain fields predicted in the multiresolution continuum analyses compare well to those observed in direct numerical simulations of the

  5. Passive mechanical properties of ovine rumen tissue

    Science.gov (United States)

    Waite, Stephen J.; Cater, John E.; Walker, Cameron G.; Amirapu, Satya; Waghorn, Garry C.; Suresh, Vinod

    2016-05-01

    Mechanical and structural properties of ovine rumen tissue have been determined using uniaxial tensile testing of tissue from four animals at five rumen locations and two orientations. Animal and orientation did not have a significant effect on the stress-strain response, but there was a significant difference between rumen locations. Histological studies showed two orthogonal muscle layers in all regions except the reticulum, which has a more isotropic structure. A quasi-linear viscoelastic model was fitted to the relaxation stage for each region. Model predictions of the ramp stage had RMS errors of 13-24% and were within the range of the experimental data.

  6. Mechanical properties of low dimensional materials

    Science.gov (United States)

    Saini, Deepika

    Recent advances in low dimensional materials (LDMs) have paved the way for unprecedented technological advancements. The drive to reduce the dimensions of electronics has compelled researchers to devise newer techniques to not only synthesize novel materials, but also tailor their properties. Although micro and nanomaterials have shown phenomenal electronic properties, their mechanical robustness and a thorough understanding of their structure-property relationship are critical for their use in practical applications. However, the challenges in probing these mechanical properties dramatically increase as their dimensions shrink, rendering the commonly used techniques inadequate. This dissertation focuses on developing techniques for accurate determination of elastic modulus of LDMs and their mechanical responses under tensile and shear stresses. Fibers with micron-sized diameters continuously undergo tensile and shear deformations through many phases of their processing and applications. Significant attention has been given to their tensile response and their structure-tensile properties relations are well understood, but the same cannot be said about their shear responses or the structure-shear properties. This is partly due to the lack of appropriate instruments that are capable of performing direct shear measurements. In an attempt to fill this void, this dissertation describes the design of an inexpensive tabletop instrument, referred to as the twister, which can measure the shear modulus (G) and other longitudinal shear properties of micron-sized individual fibers. An automated system applies a pre-determined twist to the fiber sample and measures the resulting torque using a sensitive optical detector. The accuracy of the instrument was verified by measuring G for high purity copper and tungsten fibers. Two industrially important fibers, IM7 carbon fiber and KevlarRTM 119, were found to have G = 17 and 2.4 GPa, respectively. In addition to measuring the shear

  7. Analysis of Mechanical Properties for GEM Foil

    CERN Document Server

    Chin, Yuk Ming

    2016-01-01

    In view of new assembly technique of the GEM detector; in which three foils stack is stretched to get the uniform gaps among the foils. We studied the mechanical properties of the foil material. We conditioned the samples in different environments to make them extra dry and wet. As holes are the major source of the charge amplification their deformation can effect the detector performance. Therefore in our studies we also studied at which level of the stress the holes deformation is seen. These tensile and holes deformation studies can help to optimize the stress during detector assembly.

  8. Parameter optimization for the visco-hyperelastic constitutive model of tendon using FEM.

    Science.gov (United States)

    Tang, C Y; Ng, G Y F; Wang, Z W; Tsui, C P; Zhang, G

    2011-01-01

    Numerous constitutive models describing the mechanical properties of tendons have been proposed during the past few decades. However, few were widely used owing to the lack of implementation in the general finite element (FE) software, and very few systematic studies have been done on selecting the most appropriate parameters for these constitutive laws. In this work, the visco-hyperelastic constitutive model of the tendon implemented through the use of three-parameter Mooney-Rivlin form and sixty-four-parameter Prony series were firstly analyzed using ANSYS FE software. Afterwards, an integrated optimization scheme was developed by coupling two optimization toolboxes (OPTs) of ANSYS and MATLAB for estimating these unknown constitutive parameters of the tendon. Finally, a group of Sprague-Dawley rat tendons was used to execute experimental and numerical simulation investigation. The simulated results showed good agreement with the experimental data. An important finding revealed that too many Maxwell elements was not necessary for assuring accuracy of the model, which is often neglected in most open literatures. Thus, all these proved that the constitutive parameter optimization scheme was reliable and highly efficient. Furthermore, the approach can be extended to study other tendons or ligaments, as well as any visco-hyperelastic solid materials.

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

    Science.gov (United States)

    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. Copyright © 2015 American College of Foot and Ankle

  10. Adaptation of physiological cross-sectional area and serial number of sarcomeres after tendon transfer of rat muscle.

    Science.gov (United States)

    Huijing, P A; Maas, H

    2016-03-01

    Tendon transfer surgery to a new extensor insertion was performed for musculus flexor carpi ulnaris (FCU) of young adult rats, after which animals were allowed to recover. Mechanical properties and adaptive effects on body mass, bone growth, serial number of sarcomeres, and muscle physiological cross-sectional area were studied. Between the transfer and control groups, no differences were found for body mass and forearm length growth. In contrast, transferred muscles had a 19% smaller physiological cross-sectional area and 25% fewer sarcomeres in series within its muscle fibers than control muscles, i.e., a deficit in muscle belly growth is present. Our present results confirm our the length of previous work showing a limited capability of changing the adapted transferred FCU muscle belly, as the muscle-tendon complex is stretched, so that most of the acute FCU length change must originate from the tendon. This should most likely be attributed to surgery-related additional and/or altered connective tissue linkages at the muscle-tendon boundary. The substantially increased FCU tendon length found, after recovery from surgery and adaptation to the conditions of the transferred position, is likely to be related to such enhanced stretching of the FCU tendon. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Isometric contractions reduce plantar flexor moment, Achilles tendon stiffness, and neuromuscular activity but remove the subsequent effects of stretch.

    Science.gov (United States)

    Kay, Anthony D; Blazevich, Anthony J

    2009-10-01

    The effects of isometric contractions and passive stretching on muscle-tendon mechanics and muscle activity were studied in 16 healthy human volunteers. First, peak concentric and passive ankle joint moment data were recorded on an isokinetic dynamometer with electromyographic monitoring of the triceps surae; real-time motion analysis of the lower leg and ultrasound imaging of the Achilles-medial gastrocnemius muscle-tendon junction were simultaneously conducted. Second, the subjects performed six 8-s maximal voluntary isometric contractions (MVICs) before repeating the passive and active trials. Although there was no decrease in isometric joint moment after MVICs, peak concentric moment was significantly reduced (11.5%, P static plantar flexor stretches before being retested 2 and 30 min after stretch. The stretch protocol caused no significant change in any measure. At 30 min after stretching, significant recovery in concentric moment and muscle activity was detected at dorsiflexed joint angles, while Achilles tendon stiffness and passive joint moment remained significantly reduced. These data show that the performance of MVICs interrupts the normal stretch-induced losses in active and passive plantar flexor joint moment and neuromuscular activity, largely because concentric strength and tendon properties were already affected. Importantly, the decrease in Achilles tendon stiffness remained 30 min later, which may be an important etiological factor for muscle-tendon strain injury risk.

  12. Tendon lengthening and transfer.

    Science.gov (United States)

    Fitoussi, F; Bachy, M

    2015-02-01

    Tendon lengthening and transfer are usually indicated for certain neuromuscular disorders, peripheral or central nerve injury, congenital disorder or direct traumatic or degenerative musculotendinous lesion. In musculotendinous lengthening, technique depends on muscle anatomy, degree of correction required, and the need to avoid excessive loss of force. Lengthening within the muscle or aponeurosis is stable. In the tendon, however, it may provide greater gain but is not stable and requires postoperative immobilization to avoid excessive lengthening. Tendon transfer consists in displacing a muscle's tendon insertion in order to restore function. The muscle to be transferred is chosen according to strength, architecture and course, contraction timing, intended direction, synergy and the joint moment arm to be restored. Functions to be restored have to be prioritized, and alternatives to transfer should be identified. The principles of tendon transfer require preoperative assessment of the quality of the tissue through which the transfer is to pass and of the suppleness of the joints concerned. During the procedure, transfer tension should be optimized and the neurovascular bundle should be protected. The method of fixation, whether tendon-to-bone or tendon-to-tendon suture, should be planned according to local conditions and the surgeon's experience. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  13. Patellar tendon strain is increased at the site of the jumper's knee lesion during knee flexion and tendon loading: results and cadaveric testing of a computational model.

    Science.gov (United States)

    Lavagnino, Michael; Arnoczky, Steven P; Elvin, Niell; Dodds, Julie

    2008-11-01

    Patellar tendinopathy (jumper's knee) is characterized by localized tenderness of the patellar tendon at its origin on the inferior pole of the patella and a characteristic increase in signal intensity on magnetic resonance imaging at this location. However, it is unclear why the lesion typically occurs in this area of the patellar tendon as surface strain gauge studies of the patellar tendon through the range of motion have produced conflicting results. The predicted patellar tendon strains that occur as a result of the tendon loads and patella-patellar tendon angles (PPTAs) experienced during a jump landing will be significantly increased in the area of the patellar tendon associated with patellar tendinopathy. Descriptive laboratory study. A 2-dimensional, computational, finite element model of the patella-patellar tendon complex was developed using anatomic measurements taken from lateral radiographs of a normal knee. The patella was modeled with plane strain rigid elements, and the patellar tendon was modeled with 8-node plane strain elements with neo-Hookean material properties. A tie constraint was used to join the patellar tendon and patella. Patella-patellar tendon angles corresponding to knee flexion angles between 0 degrees and 60 degrees and patellar tendon strains ranging from 5% to 15% were used as input variables into the computational model. To determine if the location of increased strain predicted by the computational model could produce isolated tendon fascicle damage in that same area, 5 human cadaveric patella-patellar tendon-tibia specimens were loaded under conditions predicted by the model to significantly increase localized tendon strain. Pre- and posttesting ultrasound images of the patella-patellar tendon specimens were obtained to document the location of any injured fascicles. Localized tendon strain at the classic location of the jumper's knee lesion was found to increase in association with an increase in the magnitude of applied

  14. Viscoelastic properties of short calf muscle-tendon units of older women: effects of slow and fast passive dorsiflexion stretches in vivo.

    Science.gov (United States)

    Gajdosik, Richard L; Vander Linden, Darl W; McNair, Peter J; Riggin, Tammy J; Albertson, Jeff S; Mattick, Danita J; Wegley, Joseph C

    2005-10-01

    Changes in connective tissues of the skeletal muscle-tendon unit (MTU) of aging animal muscles have been associated with increased passive viscoelastic properties. This study examined whether similar changes in the viscoelastic properties were present in short calf MTUs of older women in vivo. Fifteen women 68-87 years of age with short calf MTUs, as represented by limited active dorsiflexion (DF) range of motion (ROM) of plantarflexion to maximal DF at the slow velocity of 5 degrees s(-1) (0.087 rad s(-1)) and the fast velocity of 120 degrees s(-1) (2.094 rad s(-1)) with minimal surface electromyogram activity in the soleus, gastrocnemius, and tibialis anterior muscles. Two-way analysis of variance (ANOVA) tests for repeated measures (Velocity x Group) indicated that all women showed greater passive torque, average passive elastic stiffness, and total absorbed passive elastic energy for the fast stretch than for the slow stretch (P < 0.001). The older women had greater percent increases for the average passive torque (30%) and total absorbed passive elastic energy (26%) for the fast stretch than the younger women (P < 0.05), who had 17.5 and 13% increases, respectively. The older women had less maximal and average passive torque (Nm) and total absorbed passive elastic energy (degrees Nm), but greater average passive elastic stiffness (Nm degrees (-1)) at both stretch velocities (P < 0.001). The results indicated that short calf MTUs of older women have increased passive viscoelastic properties that could have implications for balance and ambulatory function.

  15. Mechanical properties of 3D ceramic nanolattices

    Science.gov (United States)

    Meza, Lucas

    Developments in advanced nanoscale fabrication techniques have allowed for the creation of 3-dimensional hierarchical structural meta-materials that can be designed with arbitrary geometry. These structures can be made on length scales spanning multiple orders of magnitude, from tens of nanometers to hundreds of microns. The smallest features are controllable on length scales where materials have been shown to exhibit size effects in their mechanical properties. Combining novel nanoscale mechanical properties with a 3-dimensional architecture enables the creation of new classes of materials with tunable and unprecedented mechanical properties. We present the fabrication and mechanical deformation of hollow tube alumina nanolattices that were fabricated using two-photon lithography direct laser writing (DLW), atomic layer deposition (ALD), and oxygen plasma etching. Nanolattices were designed in a number of different geometries including octet-truss, octahedron, and 3D Kagome. Additionally, a number of structural parameters were varied including tube wall thickness (t) , tube major axis (a) , and unit cell size (L) . The resulting nanolattices had a range of densities from ρ = 4 to 250 mg/cm3. Uniaxial compression and cyclic loading tests were performed on the nanolattices to obtain the yield strength and modulus. In these tests, a marked change in the deformation response was observed when the wall thickness was reduced below 20nm; thick-walled nanolattices (t>20nm) underwent catastrophic, brittle failure, which transitioned to a gradual, ductile-like deformation as wall thickness was reduced. Thick-walled nanolattices also exhibited no recovery after compression, while thin-walled structures demonstrated notable recovery, with some recovering by 98% after compression to 50% strain and by 80% when compressed to 90% strain. Across all geometries, unit cell sizes, and wall thicknesses, we found a consistent power law relation between strength and modulus with

  16. Mechanical properties of the beetle elytron, a biological composite material

    Science.gov (United States)

    We determined the relationship between composition and mechanical properties of elytral (modified forewing) cuticle of the beetles Tribolium castaneum and Tenebrio molitor. Elytra of both species have similar mechanical properties at comparable stages of maturation (tanning). Shortly after adult ecl...

  17. Environmental properties set cell mechanics and morphology

    Science.gov (United States)

    Janmey, Paul

    2012-02-01

    Many cell types are sensitive to mechanical signals that are produced either by application of exogenous force to their surfaces, or by the resistance that their surroundings place on forces generated by the cells themselves. Cell morphology, motility, proliferation, and protein expression all change in response to substrate stiffness. Changing the elastic moduli of substrates alters the formation of focal adhesions, the assembly of actin filaments into bundles, and the stability of intermediate filaments. The range of stiffness over which different primary cell types respond can vary over a wide range and generally reflects the elastic modulus of the tissue from which these cells were isolated. Mechanosensing depends on the type of adhesion receptor by which the cell binds, and therefore on both the molecular composition of the extracellular matrix and the nature of its link to the cytoskeleton. Many cell types can alter their own stiffness to match that of the substrate to which they adhere. The maximal elastic modulus that cells such as fibroblasts can attain is similar to that of crosslinked actin networks at the concentrations in the cell cortex. The precise mechanisms of mechanosensing are not well defined, but they presumably require an elastic connection between cell and substrate, mediated by transmembrane proteins. The viscoelastic properties of different extracellular matrices and cytoskeletal elements strongly influence the response of cells to mechanical signals, and the unusual non-linear elasticity of many biopolymer gels, characterized by strain-stiffening, leads to novel mechanisms by which cells alter their stiffness by engagement of molecular motors that produce internal stresses. Cell cortical elasticity is dominated by cytoskeletal polymer networks and can be modulated by internal tension. Simultaneous control of substrate stiffness and adhesive patterns suggests that stiffness sensing occurs on a length scale much larger than single molecular

  18. Mechanical properties of chemical vapor deposited diamond

    Science.gov (United States)

    Kant, Avinash

    The hardness, elastic modulus, subcritical crack growth and fracture toughness of chemical vapor deposited (CVD) polycrystalline diamond films have been investigated on thick (˜100 to 300 mum) free-standing films with regard to the composition, microstructure, failure mechanisms and measurement techniques. The rationale for this study was the uncertainty in measuring these properties in previous research and the variability in the composition and microstructure of the material, which may affect these properties. Two predominant micro-hardness measurement techniques, namely Vickers and Knoop indentation, were employed. Existing Young's modulus measurement techniques such as dynamic resonance and nano-indentation were reviewed for modulus measurement on these films. The validity of indentation fracture toughness measurement for CVD diamond films using micro-hardness indentation has been established based on comparison with the conventional method of tensile testing of pre-notched compact-tension samples. The fracture toughness, Ksbc, of diamond was measured using indentation methods and for the first time by the tensile testing of pre-notched fracture-mechanics type compact-tension samples. Measured Ksbc values were found to be between 5 and 7 MPa-msp{1/2} by either method. Studies on subcritical crack growth (i.e., at stress intensities less than Ksbc) indicated that CVD diamond is essentially immune to stress-corrosion cracking under sustained loads in room air, water and acid environments. Extensive studies of the microstructure and mechanisms of failure were conducted. A commonly known toughening mechanism for ceramics by weakening the grain boundary in order to promote intergranular failure and grain bridging, has been implemented to improve the toughness of CVD diamond films. Several films with nominally the same thickness but small differences in their non-diamond content were studied and a significant variation in the toughness measurements was observed

  19. Tendon Gradient Mineralization for Tendon to Bone Interface Integration

    Science.gov (United States)

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

    2014-01-01

    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 5 groups: 1) normal FDP tendon, 2) CaP (Non-extraction and mineralization without fetuin), 3) CaPEXT (Extraction by Na2HPO4 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. PMID:23939935

  20. Mechanical Properties of Graphene-Rubber Nanocomposites

    Science.gov (United States)

    Anhar, N. A. M.; Ramli, M. M.; Hambali, N. A. M. A.; Aziz, A. A.; Mat Isa, S. S.; Danial, N. S.; Abdullah, M. M. A. B.

    2017-11-01

    This research focused on development of wearable sensor device by using Prevulcanized Natural Rubber (PV) and Epoxidized Natural Rubber (ENR 50) latex incorporated with graphene oxide (GO), graphene paste, graphene powder and reduced graphene oxide (rGO) powder. The compounding formulation and calculation were based on phr (parts per hundred rubber) and all the samples were then tested for mechanical properties using Instron 5565 machine. It was found that the sonication effects on tensile strength may have better quality of tensile strength compared to non-sonicated GO. For PV incorporate GO, the optimum loading was best determined at loading 1.5 phr with or without sonication and similar result was recorded for PV/G. For ENR 50 incorporate graphene paste and rGO powder nanocomposite shows the best optimum was at 3.0 phr with 24 hours’ sonication.

  1. Mechanical Properties of Silicon Carbonitride Thin Films

    Science.gov (United States)

    Peng, Xiaofeng; Hu, Xingfang; Wang, Wei; Song, Lixin

    2003-02-01

    Silicon carbonitride thin films were synthesized by reactive rf sputtering a silicon carbide target in nitrogen and argon atmosphere, or sputtering a silicon nitride target in methane and argon atmosphere, respectively. The Nanoindentation technique (Nanoindenter XP system with a continuous stiffness measurement technique) was employed to measure the hardness and elastic modulus of thin films. The effects of sputtering power on the mechanical properties are different for the two SiCN thin films. With increasing sputtering power, the hardness and the elastic modulus decrease for the former but increase for the latter. The tendency is similar to the evolution trend of Si-C bonds in SiCN materials. This reflects that Si-C bonds provide greater hardness for SiCN thin films than Si-N and C-N bonds.

  2. Mechanical properties on geopolymer brick: A review

    Science.gov (United States)

    Deraman, L. M.; Abdullah, M. M. A.; Ming, L. Y.; Ibrahim, W. M. W.; Tahir, M. F. M.

    2017-09-01

    Bricks has stand for many years as durable construction substantial, especially in the area of civil engineering to construct buildings. Brick commonly used in the structure of buildings as a construction wall, cladding, facing perimeter, paving, garden wall and flooring. The contribution of ordinary Portland cement (OPC) in cement bricks production worldwide to greenhouse gas emissions. Due to this issue, some researchers have done their study with other materials to produce bricks, especially as a by-product material. Researchers take effort in this regard to synthesizing from by-product materials such as fly ash, bottom ash and kaolin that are rich in silicon and aluminium in the development of inorganic alumina-silicate polymer, called geopolymer Geopolymer is a polymerization reaction between various aluminosilicate oxides with silicates solution or alkali hydroxide solution forming polymerized Si-O-Al-O bonds. This paper summarized some research finding of mechanical properties of geopolymer brick using by-product materials.

  3. Peroneal tendon disorders.

    Science.gov (United States)

    Davda, Kinner; Malhotra, Karan; O'Donnell, Paul; Singh, Dishan; Cullen, Nicholas

    2017-06-01

    Pathological abnormality of the peroneal tendons is an under-appreciated source of lateral hindfoot pain and dysfunction that can be difficult to distinguish from lateral ankle ligament injuries.Enclosed within the lateral compartment of the leg, the peroneal tendons are the primary evertors of the foot and function as lateral ankle stabilisers.Pathology of the tendons falls into three broad categories: tendinitis and tenosynovitis, tendon subluxation and dislocation, and tendon splits and tears. These can be associated with ankle instability, hindfoot deformity and anomalous anatomy such as a low lying peroneus brevis or peroneus quartus.A thorough clinical examination should include an assessment of foot type (cavus or planovalgus), palpation of the peronei in the retromalleolar groove on resisted ankle dorsiflexion and eversion as well as testing of lateral ankle ligaments.Imaging including radiographs, ultrasound and MRI will help determine the diagnosis. Treatment recommendations for these disorders are primarily based on case series and expert opinion.The aim of this review is to summarise the current understanding of the anatomy and diagnostic evaluation of the peroneal tendons, and to present both conservative and operative management options of peroneal tendon lesions. Cite this article: EFORT Open Rev 2017;2:281-292. DOI: 10.1302/2058-5241.2.160047.

  4. How Obesity Affects Tendons?

    Science.gov (United States)

    Abate, Michele; Salini, Vincenzo; Andia, Isabel

    Several epidemiological and clinical observations have definitely demonstrated that obesity has harmful effects on tendons. The pathogenesis of tendon damage is multi-factorial. In addition to overload, attributable to the increased body weight, which significantly affects load-bearing tendons, systemic factors play a relevant role. Several bioactive peptides (chemerin, leptin, adiponectin and others) are released by adipocytes, and influence tendon structure by means of negative activities on mesenchymal cells. The ensuing systemic state of chronic, sub-clinic, low-grade inflammation can damage tendon structure. Metabolic disorders (diabetes, impaired glucose tolerance, and dislipidemia), frequently associated with visceral adiposity, are concurrent pathogenetic factors. Indeed, high glucose levels increase the formation of Advanced Glycation End-products, which in turn form stable covalent cross-links within collagen fibers, modifying their structure and functionality.Sport activities, so useful for preventing important cardiovascular complications, may be detrimental for tendons if they are submitted to intense acute or chronic overload. Therefore, two caution rules are mandatory: first, to engage in personalized soft training program, and secondly to follow regular check-up for tendon pathology.

  5. Mechanical Properties of Contact Lens Materials.

    Science.gov (United States)

    Kim, Eon; Saha, Mou; Ehrmann, Klaus

    2017-11-07

    To evaluate the mechanical properties of commonly available soft contact lens materials and compare results using custom-built MicroTensometer. The Young modulus, parameters for stress relaxation, and toughness of 18 types of single vision soft contact lenses were measured using custom-built MicroTensometer. Five lenses of each type were soaked in standard phosphate buffered saline and measured at a temperature of 35°C. Each lens was flattened and sliced into a rectangular strip sample using two parallel blades. The Acuvue Moist 1-Day and SofLens Daily lenses measured lowest moduli, whereas Air Optix Night & Day Aqua and Premio measured the highest. The measured moduli for silicone hydrogel materials were generally higher compared with the hydrogels except for Dailies AquaComfort Plus. The exponential curve fitted over the decay in stress showed a consistent time constant of approximately 10 sec for most lens types measured. However, the amplitude constant varied from 2.84% for SofLens Daily to 22.39% for Acuvue TruEye 1-Day. The toughness results showed that Dailies AquaComfort Plus is strong but not necessarily tough. The mechanical properties of commonly prescribed soft contact lens materials were measured using a dedicated instrument. Its reliability was demonstrated, and modulus results were compared against published data from manufacturers and other research groups. Agreement was generally good, with only a few exceptions exceeding 15% difference. The more recently released silicone hydrogel lens types have reduced modulus, approaching that of medium or high water content hydrogel materials.

  6. Mechanical properties of ceramic-polymer nanocomposites

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available Nano crystalline powders of Barium Sodium Niobate (BNN with the composition Ba3–2x Na4+x R Nb10 O30 with (R stands for rare earth = 0, x = 0 have been prepared by conventional ceramic technique. Barium Sodium Niobate can form a wide range of solid solutions, incorporating rare earth and alkali, alkaline earth elements with different compositions. The powder belonged to tungsten bronze type structure with tetragonal symmetry and lattice constants a = b = 1.2421 nm and c = 0.3903 nm. XRD (X-ray Diffraction SEM (Scanning Electron Microscope and AFM (Atomic Force Microscope studies revealed that the particle size is in the nanometer range. Composites are prepared by mixing powders of BNN with polystyrene at different volume fractions of the BNN. Melt mixing technique is carried out in a Brabender Plasticoder at a rotor speed of 60 rpm (rotations per minute for composite preparation. Mechanical properties such as stress-strain behavior, Young’s modulus, tensile strength, strain at break etc. are evaluated. Addition of filler enhances the mechanical properties of the polymer such as Young’s modulus and tensile strength. The composites showed the trend of perfect adhesion between the filler and the polymer. The filler particles are distributed relatively uniform fashion in all composites and the particles are almost spherical in shape with irregular boundaries. To explore more carefully the degree of interfacial adhesion between the two phases, the results are analyzed by using models featuring adhesion parameter. The experimental results are compared with theoretical predictions.

  7. Biodegradable compounds: Rheological, mechanical and thermal properties

    Science.gov (United States)

    Nobile, Maria Rossella; Lucia, G.; Santella, M.; Malinconico, M.; Cerruti, P.; Pantani, R.

    2015-12-01

    Recently great attention from industry has been focused on biodegradable polyesters derived from renewable resources. In particular, PLA has attracted great interest due to its high strength and high modulus and a good biocompatibility, however its brittleness and low heat distortion temperature (HDT) restrict its wide application. On the other hand, Poly(butylene succinate) (PBS) is a biodegradable polymer with a low tensile modulus but characterized by a high flexibility, excellent impact strength, good thermal and chemical resistance. In this work the two aliphatic biodegradable polyesters PBS and PLA were selected with the aim to obtain a biodegradable material for the industry of plastic cups and plates. PBS was also blended with a thermoplastic starch. Talc was also added to the compounds because of its low cost and its effectiveness in increasing the modulus and the HDT of polymers. The compounds were obtained by melt compounding in a single screw extruder and the rheological, mechanical and thermal properties were investigated. The properties of the two compounds were compared and it was found that the values of the tensile modulus and elongation at break measured for the PBS/PLA/Talc compound make it interesting for the production of disposable plates and cups. In terms of thermal resistance the compounds have HDTs high enough to contain hot food or beverages. The PLA/PBS/Talc compound can be, then, considered as biodegradable substitute for polystyrene for the production of disposable plates and cups for hot food and beverages.

  8. Engineered stem cell niche matrices for rotator cuff tendon regenerative engineering.

    Science.gov (United States)

    Peach, M Sean; Ramos, Daisy M; James, Roshan; Morozowich, Nicole L; Mazzocca, Augustus D; Doty, Steven B; Allcock, Harry R; Kumbar, Sangamesh G; Laurencin, Cato T

    2017-01-01

    Rotator cuff (RC) tears represent a large proportion of musculoskeletal injuries attended to at the clinic and thereby make RC repair surgeries one of the most widely performed musculoskeletal procedures. Despite the high incidence rate of RC tears, operative treatments have provided minimal functional gains and suffer from high re-tear rates. The hypocellular nature of tendon tissue poses a limited capacity for regeneration. In recent years, great strides have been made in the area of tendonogenesis and differentiation towards tendon cells due to a greater understanding of the tendon stem cell niche, development of advanced materials, improved scaffold fabrication techniques, and delineation of the phenotype development process. Though in vitro models for tendonogenesis have shown promising results, in vivo models have been less successful. The present work investigates structured matrices mimicking the tendon microenvironment as cell delivery vehicles in a rat RC tear model. RC injuries augmented with a matrix delivering rat mesenchymal stem cells (rMSCs) showed enhanced regeneration over suture repair alone or repair with augmentation, at 6 and 12-weeks post-surgery. The local delivery of rMSCs led to increased mechanical properties and improved tissue morphology. We hypothesize that the mesenchymal stem cells function to modulate the local immune and bioactivity environment through autocrine/paracrine and/or cell homing mechanisms. This study provides evidence for improved tendon healing with biomimetic matrices and delivered MSCs with the potential for translation to larger, clinical animal models. The enhanced regenerative healing response with stem cell delivering biomimetic matrices may represent a new treatment paradigm for massive RC tendon tears.

  9. Tendon neuroplastic training: changing the way we think about tendon rehabilitation: a narrative review

    Science.gov (United States)

    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

  10. Trabecular Bone Mechanical Properties and Fractal Dimension

    Science.gov (United States)

    Hogan, Harry A.

    1996-01-01

    Countermeasures for reducing bone loss and muscle atrophy due to extended exposure to the microgravity environment of space are continuing to be developed and improved. An important component of this effort is finite element modeling of the lower extremity and spinal column. These models will permit analysis and evaluation specific to each individual and thereby provide more efficient and effective exercise protocols. Inflight countermeasures and post-flight rehabilitation can then be customized and targeted on a case-by-case basis. Recent Summer Faculty Fellowship participants have focused upon finite element mesh generation, muscle force estimation, and fractal calculations of trabecular bone microstructure. Methods have been developed for generating the three-dimensional geometry of the femur from serial section magnetic resonance images (MRI). The use of MRI as an imaging modality avoids excessive exposure to radiation associated with X-ray based methods. These images can also detect trabecular bone microstructure and architecture. The goal of the current research is to determine the degree to which the fractal dimension of trabecular architecture can be used to predict the mechanical properties of trabecular bone tissue. The elastic modulus and the ultimate strength (or strain) can then be estimated from non-invasive, non-radiating imaging and incorporated into the finite element models to more accurately represent the bone tissue of each individual of interest. Trabecular bone specimens from the proximal tibia are being studied in this first phase of the work. Detailed protocols and procedures have been developed for carrying test specimens through all of the steps of a multi-faceted test program. The test program begins with MRI and X-ray imaging of the whole bones before excising a smaller workpiece from the proximal tibia region. High resolution MRI scans are then made and the piece further cut into slabs (roughly 1 cm thick). The slabs are X-rayed again

  11. Role of biomechanics in the understanding of normal, injured, and healing ligaments and tendons.

    Science.gov (United States)

    Jung, Ho-Joong; Fisher, Matthew B; Woo, Savio L-Y

    2009-05-20

    their biomechanical properties. Specifically, we hope the reader will pay attention to how the properties of these tissues can be altered due to various experimental and biologic factors. Following this background material, we will present how biomechanics can be applied to gain an understanding of the mechanisms as well as clinical management of various ligament and tendon ailments. To conclude, new technology, including imaging and robotics as well as functional tissue engineering, that could form novel treatment strategies to enhance healing of ligament and tendon are presented.

  12. Role of biomechanics in the understanding of normal, injured, and healing ligaments and tendons

    Directory of Open Access Journals (Sweden)

    Jung Ho-Joong

    2009-05-01

    appropriate methodologies used to obtain their biomechanical properties. Specifically, we hope the reader will pay attention to how the properties of these tissues can be altered due to various experimental and biologic factors. Following this background material, we will present how biomechanics can be applied to gain an understanding of the mechanisms as well as clinical management of various ligament and tendon ailments. To conclude, new technology, including imaging and robotics as well as functional tissue engineering, that could form novel treatment strategies to enhance healing of ligament and tendon are presented.

  13. Nonoperative, dynamic treatment of acute achilles tendon rupture

    DEFF Research Database (Denmark)

    Barfod, Kristoffer Weisskirchner; Bencke, Jesper; Lauridsen, Hanne Bloch

    2015-01-01

    ° dorsiflexion, the stiffness during slow stretching, and the maximal strength were measured in both limbs. The stiffness of the plantar flexor muscle-tendon complex in the terminal part of dorsiflexion was significantly increased (p = .024) in the non-weightbearing group at 12 months. The peak passive torque......Acute Achilles tendon rupture alters the biomechanical properties of the plantar flexor muscle-tendon complex that can affect functional performance and the risk of repeat injury. The purpose of the present study was to compare the biomechanical properties of the plantar flexor muscle......-tendon complex in patients randomized to early weightbearing or non-weightbearing in the nonoperative treatment of Achilles tendon rupture. A total of 60 patients were randomized to full weightbearing from day 1 of treatment or non-weightbearing for 6 weeks. After 6 and 12 months, the peak passive torque at 20...

  14. A novel postoperative immobilization model for murine Achilles tendon sutures.

    Science.gov (United States)

    Shibuya, Yoichiro; Takayama, Yuzo; Kushige, Hiroko; Jacinto, Sandra; Sekido, Mitsuru; Kida, Yasuyuki S

    2016-08-01

    The body's motion and function are all in part effected by a vital tissue, the tendon. Tendon injury often results in limited functioning after postoperative procedures and even for a long time after rehabilitation. Although numerous studies have reported surgical procedures using animal models which have contributed to both basic and clinical research, modeling of tendon sutures or postoperative immobilizations has not been performed on small experimental animals, such as mice. In this study we have developed an easy Achilles tendon suture and postoperative ankle fixation model in a mouse. Right Achilles tendons were incised and 10-0 nylons were passed through the proximal and distal ends using a modified Kessler method. Subsequently, the right ankle was immobilized in a plantarflexed position with novel splints, which were made from readily available extension tubes. Restriction of the tendon using handmade splints reduced swelling, as opposed to fixating with the usual plaster of Paris. Using this method, the usage of the right Achilles tendons began on postoperative days 13.5 ± 4.6, which indicated healing within two weeks. Therefore our simple short-term murine Achilles tendon suture procedure is useful for studying immediate tendon repair mechanisms in various models, including genetically-modified mice. © The Author(s) 2015.

  15. Adequacy of palmaris longus and plantaris tendons for tendon grafting.

    Science.gov (United States)

    Jakubietz, Michael G; Jakubietz, Danni F; Gruenert, Joerg G; Zahn, Robert; Meffert, Rainer H; Jakubietz, Rafael G

    2011-04-01

    The reconstruction of tendon defects is challenging. The palmaris longus and plantaris tendon are generally considered best for tendon grafting. Only a few studies have examined whether these tendons, when present, meet criteria for successful grafting. The purpose of this study was to evaluate these tendons in regard to adequacy as tendon grafts. To evaluate adequacy for grafting, the palmaris longus and plantaris tendons were harvested from 92 arms and legs of 46 cadavers. Macroscopic evaluation and measurements concerning presence, length, and diameter of the tendons were obtained. Criteria for adequacy were a minimum length of 15 cm with diameter of 3 mm or, alternatively, 30 cm with a diameter of 1.5 mm. The palmaris longus tendon was present bilaterally in 36 cases and was absent bilaterally in 4 cases. The plantaris tendon was present bilaterally in 38 cases and absent bilaterally in 4 cases. In 29 cadavers, the palmaris longus tendon did not meet the criteria to be used as a tendon graft. Only in 8 cases were the tendons satisfactory for grafting bilaterally. The plantaris tendon met criteria for grafting in 20 cases bilaterally. In 17 cases, the tendons were considered inadequate bilaterally. Despite their presence, the palmaris longus and plantaris tendons are adequate for grafting less often than previously thought. In less than 50%, the tendons, although present, would serve as useful grafts. Our findings underscore the importance of choosing a second donor site before surgery in case the primarily selected tendon is not found to be suitable. Copyright © 2011 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  16. Regulatory Mechanisms of the Ihh/PTHrP Signaling Pathway in Fibrochondrocytes in Entheses of Pig Achilles Tendon

    Directory of Open Access Journals (Sweden)

    Xuesong Han

    2016-01-01

    Full Text Available This study is aimed at exploring the effect of stress stimulation on the proliferation and differentiation of fibrochondrocytes in entheses mediated via the Indian hedgehog (Ihh/parathyroid hormone-related protein (PTHrP signaling pathway. Differential stress stimulation on fibrochondrocytes in entheses was imposed. Gene expression and protein levels of signaling molecules including collagen type I (Col I, Col II, Col X, Ihh, and PTHrP in the cytoplasm of fibrochondrocytes were detected. Ihh signal blocking group was set up using Ihh signaling pathway-specific blocking agent cyclopamine. PTHrP enhancement group was set up using PTHrP reagent. Ihh/PTHrP double intervention group, as well as control group, was included to study the regulatory mechanisms of the Ihh/PTHrP signaling pathway in fibrochondrocytes. Under low cyclic stress tensile (CTS, PTHrP, Col I, and Col II gene expression and protein synthesis increased. Under high CTS, Ihh and Col X gene expression and protein synthesis increased. Blocking Ihh signaling with cyclopamine resulted in reduced PTHrP gene expression and protein synthesis and increased Col X gene expression and protein synthesis. Ihh and PTHrP coregulate fibrochondrocyte proliferation and differentiation in entheses through negative feedback regulation. Fibrochondrocyte is affected by the CTS. This phenomenon is regulated by stress stimulation through the Ihh/PTHrP signaling pathway.

  17. Tendon Transfers for Tetraplegia.

    Science.gov (United States)

    Bednar, Michael S

    2016-08-01

    It is estimated that 65% to 75% of patients with cervical spinal cord injuries could benefit from upper extremity tendon transfer surgery. The goals of surgery are to restore elbow extension, as well as hand pinch, grasp, and release. Patients who have defined goals, actively participate in therapy, and understand expected outcomes, appear to have the highest satisfaction following tendon transfer procedures. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Mechanical properties of thermal protection system materials.

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, Robert Douglas; Bronowski, David R.; Lee, Moo Yul; Hofer, John H.

    2005-06-01

    An experimental study was conducted to measure the mechanical properties of the Thermal Protection System (TPS) materials used for the Space Shuttle. Three types of TPS materials (LI-900, LI-2200, and FRCI-12) were tested in 'in-plane' and 'out-of-plane' orientations. Four types of quasi-static mechanical tests (uniaxial tension, uniaxial compression, uniaxial strain, and shear) were performed under low (10{sup -4} to 10{sup -3}/s) and intermediate (1 to 10/s) strain rate conditions. In addition, split Hopkinson pressure bar tests were conducted to obtain the strength of the materials under a relatively higher strain rate ({approx}10{sup 2} to 10{sup 3}/s) condition. In general, TPS materials have higher strength and higher Young's modulus when tested in 'in-plane' than in 'through-the-thickness' orientation under compressive (unconfined and confined) and tensile stress conditions. In both stress conditions, the strength of the material increases as the strain rate increases. The rate of increase in LI-900 is relatively small compared to those for the other two TPS materials tested in this study. But, the Young's modulus appears to be insensitive to the different strain rates applied. The FRCI-12 material, designed to replace the heavier LI-2200, showed higher strengths under tensile and shear stress conditions. But, under a compressive stress condition, LI-2200 showed higher strength than FRCI-12. As far as the modulus is concerned, LI-2200 has higher Young's modulus both in compression and in tension. The shear modulus of FRCI-12 and LI-2200 fell in the same range.

  19. Achilles tendon stiffness is unchanged one hour after a marathon.

    Science.gov (United States)

    Peltonen, Jussi; Cronin, Neil J; Stenroth, Lauri; Finni, Taija; Avela, Janne

    2012-10-15

    Overuse-induced injuries have been proposed as a predisposing factor for Achilles tendon (AT) ruptures. If tendons can be overloaded, their mechanical properties should change during exercise. Because there data are lacking on the effects of a single bout of long-lasting exercise on AT mechanical properties, the present study measured AT stiffness before and after a marathon. AT stiffness was determined as the slope of the force-elongation curve between 10 and 80% of maximum voluntary force. AT force-elongation characteristics were measured in an ankle dynamometer using simultaneous motion-capture-assisted ultrasonography. Oxygen consumption and ankle kinematics were also measured on a treadmill at the marathon pace. All measurements were performed before and after the marathon. AT stiffness did not change significantly from the pre-race value of 197±62 N mm(-1) (mean ± s.d.) to the post-race value of 206±59 N mm(-1) (N=12, P=0.312). Oxygen consumption increased after the race by 7±10% (Pmarathon induced a change in their foot strike technique. The AT of the physically active individuals seems to be able to resist mechanical changes under physiological stress. We therefore suggest that natural loading, like in running, may not overstress the AT or predispose it to injury. In addition, decreased running economy, as well as altered foot strike technique, was probably attributable to muscle fatigue.

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

    Science.gov (United States)

    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.

  1. Biomechanical analysis of partial flexor tendon lacerations in zone II of human cadavers.

    Science.gov (United States)

    Manning, David W; Spiguel, Andre R; Mass, Daniel P

    2010-01-01

    The aims of this study were to examine nonrepaired 90% partial lacerations of human cadaver flexor digitorum profundus (FDP) tendon after simulated active motion, and to assess the residual ultimate tensile strength. Partial, transverse zone II flexor tendon lacerations were made in the volar 90% of the tendon substance in 10 FDP tendons from 5 fresh-frozen human cadaver hands. The tendons were cycled in the curvilinear fashion described by Greenwald 500 times to a tension 25% greater than the maximum in vivo active FDP flexion force measured by Schuind and colleagues. The tendons were then loaded to failure using the same curvilinear model. No tendons ruptured during cycling. Triggering occurred in 3 tendons. All 3 began triggering early in the cycling process, and continued to trigger throughout the remainder of the 500 cycles. The observed triggering mechanics in each case involved the interaction of the proximal face of the lacerated tendon with Camper's chiasm and the pulley edges during extension. The load to failure value of the 90% partially lacerated tendons averaged 141.7 +/- 13 N (mean +/- standard deviation). Tendon failure occurred by delamination of the intact collagen fibers from the distal, discontinuous 90% of the tendon. Cadaveric transverse zone II partial flexor tendon lacerations have residual tensile strength greater than the force required for protected active mobilization. Copyright 2010. Published by Elsevier Inc.

  2. Mechanical Properties of Moringa ( Moringa oleifera ) Seeds in ...

    African Journals Online (AJOL)

    Mechanical properties are very important in the design of machines and the analysis of the behaviour of products during agricultural processing. In this research work, the mechanical properties of Moringa were determined as design parameters for the development of an oil expeller for the crop. The properties were the ...

  3. chemical and mechanical properties of velvet tamarind fruit (dialium ...

    African Journals Online (AJOL)

    This study was conducted to investigate the chemical and mechanical properties of unshelled (black), shelled (yellow) and kernel of Dialium guineense fruit. The chemical properties investigated include some proximate and mineral elements. The mechanical properties were bio-yield force, rupture force, deformation at ...

  4. Mechanical Properties of Khaya and Albizia Films Intended for ...

    African Journals Online (AJOL)

    The mechanical properties of khaya and albizia films have been studied to assess their suitability for pharmaceutical coating. The two gums were initially characterized in terms of their physicochemical properties. The mechanical properties evaluated were tensile strength, elastic modulus, and elongation at break, strain ...

  5. High stress monitoring of prestressing tendons in nuclear concrete vessels using fibre-optic sensors

    Energy Technology Data Exchange (ETDEWEB)

    Perry, M., E-mail: marcus.perry@strath.ac.uk [Institute for Energy and Environment, University of Strathclyde, 204 George Street, Glasgow G1 1XW (United Kingdom); Yan, Z.; Sun, Z.; Zhang, L. [Aston Institute of Photonic Technologies, Aston University, Birmingham B4 7ET (United Kingdom); Niewczas, P. [Institute for Energy and Environment, University of Strathclyde, 204 George Street, Glasgow G1 1XW (United Kingdom); Johnston, M. [Civil Design Group, EDF Energy, Nuclear Generation, East Kilbride G74 5PG (United Kingdom)

    2014-03-15

    Highlights: • We weld radiation-resistant optical fibre strain sensors to steel prestressing tendons. • We prove the sensors can survive 1300 MPa stress (80% of steel's tensile strength). • Mechanical relaxation of sensors is characterised under 1300 MPa stress over 10 h. • Strain transfer between tendon and sensor remains at 69% after relaxation. • Sensors can withstand and measure deflection of tendon around a 4.5 m bend radius. - Abstract: Maintaining the structural health of prestressed concrete nuclear containments is a key element in ensuring nuclear reactors are capable of meeting their safety requirements. This paper discusses the attachment, fabrication and characterisation of optical fibre strain sensors suitable for the prestress monitoring of irradiated steel prestressing tendons. The all-metal fabrication and welding process allowed the instrumented strand to simultaneously monitor and apply stresses up to 1300 MPa (80% of steel's ultimate tensile strength). There were no adverse effects to the strand's mechanical properties or integrity. After sensor relaxation through cyclic stress treatment, strain transfer between the optical fibre sensors and the strand remained at 69%. The fibre strain sensors could also withstand the non-axial forces induced as the strand was deflected around a 4.5 m bend radius. Further development of this technology has the potential to augment current prestress monitoring practices, allowing distributed measurements of short- and long-term prestress losses in nuclear prestressed-concrete vessels.

  6. History of flexor tendon repair.

    Science.gov (United States)

    Manske, Paul R

    2005-05-01

    The first issue of Hand Clinics published 20 years ago was devoted to flexor tendon injuries. This was most appropriate, because no subject in hand surgery has sparked more interest or discussion. That inaugural issue included excellent presentations on the basic science of tendon injuries (anatomy, biomechanics, nutrition, healing, adhesions) and the clinical practice of tendon repair. Of interest, there was no presentation on the fascinating history of flexor tendon surgery. It is most appropriate, therefore, that this current update of the flexor tendon begins with a historical review of the evolution of flexor tendon repair.

  7. An Investigation of the Mechanical Properties of Sisal Fibre, Loofah ...

    African Journals Online (AJOL)

    The mechanical properties of sisal fibre, loofah matt, epoxy resin and their resulting composites were determined experimentally. The influence of volume fraction of the reinforcing fibres and matt on the mechanical properties of the composites was investigated. It was found that loofah matt reduces the mechanical ...

  8. Structural Properties and Mechanical Durability of Extruded Fish Feed

    DEFF Research Database (Denmark)

    Haubjerg, Anders Fjeldbo; Veje, Christian; Jørgensen, Bo Nørregaard

    2015-01-01

    This article investigates the possible correlation between mechanical properties of fish feed pellets and their mechanical durability. Mechanical properties were obtained by texture profile analysis (TPA) and stress relaxation test (SRT) of different types of fish feed. The results were correlated...

  9. Effect of fibre content and alkali treatment on mechanical properties ...

    Indian Academy of Sciences (India)

    Effect of fibre content and alkali treatment on mechanical properties of Roystonea regia-reinforced epoxy partially biodegradable composites ... Roystonea regia fibre; epoxy resin; alkali treatment; mechanical properties. ... Department of Mechanical Engineering, National Institute of Technology, Warangal 506 004, India ...

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

    Science.gov (United States)

    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.

  11. Effect of an aqueous extract of Phaseolus vulgaris on the properties of tail tendon collagen of rats with streptozotocin-induced diabetes

    Directory of Open Access Journals (Sweden)

    L. Pari

    2003-07-01

    Full Text Available Changes in the structural and functional properties of collagen caused by advanced glycation might be of importance for the etiology of late complications in diabetes. The present study was undertaken to investigate the influence of oral administration of aqueous pod extract (200 mg/kg body weight of Phaseolus vulgaris, an indigenous plant used in Ayurvedic Medicine in India, on collagen content and characteristics in the tail tendon of streptozotocin-diabetic rats. In diabetic rats, collagen content (117.01 ± 6.84 mg/100 mg tissue as well as its degree of cross-linking was increased, as shown by increased extent of glycation (21.70 ± 0.90 µg glucose/mg collagen, collagen-linked fluorescence (52.8 ± 3.0 AU/µmol hydroxyproline, shrinkage temperature (71.50 ± 2.50ºC and decreased acid (1.878 ± 0.062 mg hydroxyproline/100 mg tissue and pepsin solubility (1.77 ± 0.080 mg hydroxyproline/100 mg tissue. The alpha/ß ratio of acid- (1.69 and pepsin-soluble (2.00 collagen was significantly decreased in streptozotocin-diabetic rats. Administration of P. vulgaris for 45 days to streptozotocin-diabetic rats significantly reduced the accumulation and cross-linking of collagen. The effect of P. vulgaris was compared with that of glibenclamide, a reference drug administered to streptozotocin-diabetic rats at the dose of 600 µg/kg body weight for 45 days by gavage. The effects of P. vulgaris (collagen content, 64.18 ± 1.97; extent of glycation, 12.00 ± 0.53; collagen-linked fluorescence, 33.6 ± 1.9; shrinkage temperature, 57.0 ± 1.0; extent of cross-linking - acid-soluble collagen, 2.572 ± 0.080, and pepsin-soluble collagen, 2.28 ± 0.112 were comparable with those of glibenclamide (collagen content, 71.5 ± 2.04; extent of glycation, 13.00 ± 0.60; collagen-linked fluorescence, 38.9 ± 2.0; shrinkage temperature, 59.0 ± 1.5; extent of cross-linking - acid-soluble collagen, 2.463 ± 0.078, and pepsin-soluble collagen, 2.17 ± 0.104. In

  12. Effect of an aqueous extract of Phaseolus vulgaris on the properties of tail tendon collagen of rats with streptozotocin-induced diabetes.

    Science.gov (United States)

    Pari, L; Venkateswaran, S

    2003-07-01

    Changes in the structural and functional properties of collagen caused by advanced glycation might be of importance for the etiology of late complications in diabetes. The present study was undertaken to investigate the influence of oral administration of aqueous pod extract (200 mg/kg body weight) of Phaseolus vulgaris, an indigenous plant used in Ayurvedic Medicine in India, on collagen content and characteristics in the tail tendon of streptozotocin-diabetic rats. In diabetic rats, collagen content (117.01 6.84 mg/100 mg tissue) as well as its degree of cross-linking was increased, as shown by increased extent of glycation (21.70 0.90 g glucose/mg collagen), collagen-linked fluorescence (52.8 3.0 AU/ mol hydroxyproline), shrinkage temperature (71.50 2.50 C) and decreased acid (1.878 0.062 mg hydroxyproline/100 mg tissue) and pepsin solubility (1.77 0.080 mg hydroxyproline/100 mg tissue). The alpha/ ratio of acid- (1.69) and pepsin-soluble (2.00) collagen was significantly decreased in streptozotocin-diabetic rats. Administration of P. vulgaris for 45 days to streptozotocin-diabetic rats significantly reduced the accumulation and cross-linking of collagen. The effect of P. vulgaris was compared with that of glibenclamide, a reference drug administered to streptozotocin-diabetic rats at the dose of 600 g/kg body weight for 45 days by gavage. The effects of P. vulgaris (collagen content, 64.18 1.97; extent of glycation, 12.00 0.53; collagen-linked fluorescence, 33.6 1.9; shrinkage temperature, 57.0 1.0; extent of cross-linking - acid-soluble collagen, 2.572 0.080, and pepsin-soluble collagen, 2.28 0.112) were comparable with those of glibenclamide (collagen content, 71.5 2.04; extent of glycation, 13.00 0.60; collagen-linked fluorescence, 38.9 2.0; shrinkage temperature, 59.0 1.5; extent of cross-linking - acid-soluble collagen, 2.463 0.078, and pepsin-soluble collagen, 2.17 0.104). In conclusion, administration of P. vulgaris pods had a positive influence on the

  13. [Achilles tendon rupture].

    Science.gov (United States)

    Thermann, H; Hüfner, T; Tscherne, H

    2000-03-01

    The treatment of acute of Achilles tendon rupture experienced a dynamic development in the last ten years. Decisive for this development was the application of MRI and above all the ultrasonography in the diagnostics of the pathological changes and injuries of tendons. The question of rupture morphology as well as different courses of healing could be now evaluated objectively. These advances led consequently to new modalities in treatment concepts and rehabilitation protocols. The decisive input for improvements of the outcome results and particularly the shortening of the rehabilitation period came with introduction of the early functional treatment in contrast to immobilizing plaster treatment. In a prospective randomized study (1987-1989) at the Trauma Dept. of the Hannover Medical School could show no statistical differences comparing functional non-operative with functional operative therapy with a special therapy boot (Variostabil/Adidas). The crucial criteria for therapy selection results from the sonographically measured position of the tendon stumps in plantar flexion (20 degrees). With complete adaptation of the tendons' ends surgical treatment does not achieve better results than non-operative functional treatment in term of tendon healing and functional outcome. Regarding the current therapeutic standards each method has is advantages and disadvantages. Both, the operative and non-operative functional treatment enable a stable tendon healing with a low risk of re-rupture (1-2%). Meanwhile there is consensus for early functional after-treatment of the operated Achilles' tendons. There seems to be a trend towards non-operative functional treatment in cases of adequate sonographical findings, or to minimal invasive surgical techniques.

  14. The effects of 4 weeks stretching training to the point of pain on flexibility and muscle tendon unit properties.

    Science.gov (United States)

    Muanjai, Pornpimol; Jones, David A; Mickevicius, Mantas; Satkunskiene, Danguole; Snieckus, Audrius; Rutkauskaite, Renata; Mickeviciene, Dalia; Kamandulis, Sigitas

    2017-08-01

    The purpose of this study was to compare the benefits and possible problems of 4 weeks stretching when taken to the point of pain (POP) and to the point of discomfort (POD). Twenty-six physically active women (20 ± 1.1 years) took part in group-based stretching classes of the hamstring muscles, 4 times per week for 4 weeks, one group one stretching to POD, the other to POP. Passive stiffness, joint range of motion (ROM), maximal isometric torque and concentric knee flexion torque, were measured before training and 2 days after the last training session. Hip flexion ROM increased by 14.1° (10.1°-18.1°) and 19.8° (15.1°-24.5°) and sit-and-reach by 7.6 (5.2-10.0) cm and 7.5 (5.0-10.0) cm for POD and POP, respectively (Mean and 95% CI; p stretching to POP increased flexibility and had no detrimental effects on muscle function but the benefits were no better than when stretching to POD so there is no justification for recommending painful stretching. The improvements in flexibility over 4 weeks of stretching training appear to be largely due to changes in the perception of pain rather than physical properties of the MTU although less flexible individuals benefited more from the training and increased hamstring muscle length.

  15. Development of a reinforced electrochemically aligned collagen bioscaffold for tendon tissue engineering applications

    Science.gov (United States)

    Uquillas Paredes, Jorge Alfredo

    Type-I collagen is a promising biomaterial that can be used to synthesize bioscaffolds as a strategy to regenerate and repair damaged tendons. The existing in vitro prepared collagen bioscaffolds are in the form of gels, foams, or extruded fibers. These bioscaffolds readily present sites for attachment of biological factors and cells; however, they have extremely poor biomechanical properties in comparison to the properties of native tendons. The biomechanical function of type-I collagen bioscaffolds needs to be elevated to the level of natural tissues for this biomaterial to replace mechanically challenged tendons in a functionally meaningful way. The overall goal of this dissertation is to develop a reinforced electrochemically aligned collagenous bioscaffold for applications in tendon tissue engineering. The bioscaffold is synthesized by a unique electrochemical process via isoelectric focusing (IEF) to attain a very high degree of molecular alignment and packing density. This dissertation presents progress made on four aims: A) development of simple and descriptive electrochemical theory via the mathematical model of IEF and the forces acting on collagen alignment under an electric field; B) optimization of the post-alignment PBS treatment step to achieve d- banding pattern in uncrosslinked electrochemically aligned collagen (ELAC) bioscaffolds; C) optimization of the best crosslinking protocol to produce the strongest possible ELAC biomaterial with excellent cellular compatibility; and D) in vivo evaluation of the biocompatibility and biodegradability properties of electronically aligned collagen bioscaffolds. The results of this dissertation provide strong evidence showing that reinforced ELAC bioscaffolds could be used clinically in the future to repair damaged tendons.

  16. Moderate-duration static stretch reduces active and passive plantar flexor moment but not Achilles tendon stiffness or active muscle length.

    Science.gov (United States)

    Kay, Anthony D; Blazevich, Anthony J

    2009-04-01

    The effects of static stretch on muscle and tendon mechanical properties and muscle activation were studied in fifteen healthy human volunteers. Peak active and passive moment data were recorded during plantar flexion trials on an isokinetic dynamometer. Electromyography (EMG) monitoring of the triceps surae muscles, real-time motion analysis of the lower leg, and ultrasound imaging of the Achilles-medial gastrocnemius muscle-tendon junction were simultaneously conducted. Subjects performed three 60-s static stretches before being retested 2 min and 30 min poststretch. There were three main findings in the present study. First, peak concentric moment was significantly reduced after stretch; 60% of the deficit recovered 30 min poststretch. This was accompanied by, and correlated with (r = 0.81; P stretch and at 30 min poststretch; however, no change in tendon stiffness was detected. Third, passive joint moment was significantly reduced after stretch, and this was accompanied by significant reductions in medial gastrocnemius passive muscle stiffness; both measures fully recovered by 30 min poststretch. These data indicate that the stretching protocol used in this study induced losses in concentric moment that were accompanied by, and related to, reductions in neuromuscular activity, but they were not associated with alterations in tendon stiffness or shorter muscle operating length. Reductions in passive moment were associated with reductions in muscle stiffness, whereas tendon mechanics were unaffected by the stretch. Importantly, the impact on mechanical properties and neuromuscular activity was minimal at 30 min poststretch.

  17. Ultrasonic nondestructive evaluation, microstructure, and mechanical property interrelations

    Science.gov (United States)

    Vary, A.

    1984-01-01

    Ultrasonic techniques for mechanical property characterizations are reviewed and conceptual models are advanced for explaining and interpreting the empirically based results. At present, the technology is generally empirically based and is emerging from the research laboratory. Advancement of the technology will require establishment of theoretical foundations for the experimentally observed interrelations among ultrasonic measurements, mechanical properties, and microstructure. Conceptual models are applied to ultrasonic assessment of fracture toughness to illustrate an approach for predicting correlations found among ultrasonic measurements, microstructure, and mechanical properties.

  18. Quadriceps Tendon Rupture and Contralateral Patella Tendon Avulsion Post Primary Bilateral Total Knee Arthroplasty: A Case Report

    Directory of Open Access Journals (Sweden)

    Gaurav Sharma

    2016-07-01

    Full Text Available Background: Extensor mechanism failure secondary to knee replacement could be due to tibial tubercle avulsion, Patellar tendon rupture, patellar fracture or quadriceps tendon rupture. An incidence of Patella tendon rupture of 0.17% and Quadriceps tendon rupture of around 0.1% has been reported after Total knee arthroplasty. These are considered a devastating complication that substantially affects the clinical results and are challenging situations to treat with surgery being the mainstay of the treatment. Case Description: We report here an interesting case of a patellar tendon rupture of one knee and Quadriceps tendon rupture of the contralateral knee following simultaneous bilateral knee replacement in a case of inflammatory arthritis patient. End to end repair for Quadriceps tear and augmentation with Autologous Hamstring tendon graft was done for Patella tendon rupture. OUTCOME: Patient was followed up for a period of 1 year and there was no Extension lag with a flexion of 100 degrees in both the knees. DISCUSSION: The key learning points and important aspects of diagnosing these injuries early and the management techniques are described in this unique case of bilateral extensor mechanism disruption following knee replacements.

  19. Real-time observations of mechanical stimulus-induced enhancements of mechanical properties in osteoblast cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xu; Liu Xiaoli; Sun Jialun [State Key Laboratory of Bioactive Materials, School of Physics, Nankai University, Tianjin 300073 (China); He Shuojie [State Key Laboratory of Bioactive Materials, School of Physics, Nankai University, Tianjin 300073 (China); Department of Physics, Pusan National University, Pusan (Korea, Republic of); Lee, Imshik [State Key Laboratory of Bioactive Materials, School of Physics, Nankai University, Tianjin 300073 (China)], E-mail: ilee@nankai.edu.cn2; Pak, Hyuk Kyu [Department of Physics, Pusan National University, Pusan (Korea, Republic of)

    2008-09-15

    Osteoblast, playing a key role in the pathophysiology of osteoporosis, is one of the mechanical stress sensitive cells. The effects of mechanical load-induced changes of mechanical properties in osteoblast cells were studied at real-time. Osteoblasts obtained from young Wister rats were exposed to mechanical loads in different frequencies and resting intervals generated by atomic force microscopy (AFM) probe tip and simultaneously measured the changes of the mechanical properties by AFM. The enhancement of the mechanical properties was observed and quantified by the increment of the apparent Young's modulus, E{sup *}. The observed mechanical property depended on the frequency of applied tapping loads. For the resting interval is 50 s, the mechanical load-induced enhancement of E{sup *}-values disappears. It seems that the enhanced mechanical property was recover able under no additional mechanical stimulus.

  20. Steroid injections - tendon, bursa, joint

    Science.gov (United States)

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

  1. Compression, Mechanical and Release Properties of Chloroquine ...

    African Journals Online (AJOL)

    Purpose: A study was made of the binding properties of trifoliate yam starch, obtained from Dioscorea dumetorum (Pax), in chloroquine phosphate tablet formulations in comparison with official corn starch. Method: Compressional properties were analyzed using density measurements and compression equations of Heckel ...

  2. Tendon Driven Finger Actuation System

    Science.gov (United States)

    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); hide

    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.

  3. Mechanical properties of non-woven glass fiber geopolymer composites

    Science.gov (United States)

    Rieger, D.; Kadlec, J.; Pola, M.; Kovářík, T.; Franče, P.

    2017-02-01

    This experimental research focuses on mechanical properties of non-woven glass fabric composites bound by geopolymeric matrix. This study investigates the effect of different matrix composition and amount of granular filler on the mechanical properties of final composites. Matrix was selected as a metakaolin based geopolymer hardened by different amount of potassium silicate activator. The ceramic granular filler was added into the matrix for investigation of its impact on mechanical properties and workability. Prepared pastes were incorporated into the non-woven fabrics by hand roller and final composites were stacked layer by layer to final thickness. The early age hardening of prepared pastes were monitored by small amplitude dynamic rheology approach and after 28 days of hardening the mechanical properties were examined. The electron microscopy was used for detail description of microstructural properties. The imaging methods revealed good wettability of glass fibers by geopolymeric matrix and results of mechanical properties indicate usability of these materials for constructional applications.

  4. The role of the peroneal tendons in passive stabilisation of the ankle joint: an in vitro study.

    Science.gov (United States)

    Ziai, Pejman; Benca, Emir; von Skrbensky, Gobert; Graf, Alexandra; Wenzel, Florian; Basad, Erhan; Windhager, Reinhard; Buchhorn, Tomas

    2013-06-01

    Peroneal tendons are known as active stabilizer in acute ankle sprain while an intact ankle mortise and intact lateral ligaments are required for passive stability of the ankle joint. The goal of this study is to determine the peroneal tendons as passive stabilizer in case of lateral ligament instability. Twelve (12) human lower leg cadaver specimens underwent a torsion simulation in the testing system, 858 Mini Bionix(®) (MTS(®) Systems Corporation, Eden Prairie, MN, USA) and a specially designed mounting platform for the specimens. The preset torsion between tibia and calcaneus was primarily set at 30° of internal rotation during plantar flexion and hindfoot inversion. The resisting torque around mechanical tibial axis was recorded which ensures stability in ankle sprain trauma. The first series of measurements were performed on healthy specimens and the following after transecting structures in following order: ATFL (anterior talofibular ligament) in combination with CFL (calcaneofibular ligament), followed by peroneus longus tendon and finally peroneus brevis tendon. The combined lateral ATFL and CFL instability shows a decrease of the resisting torque which ensures stability in ankle sprain trauma. Only a transection of PLT with existing lateral dual-ligament instability results in a significant decrease in torque (p lesion in ankle sprain trauma. A deficiency in viscoelastic properties of the peroneus longus tendon must be considered in diagnostic and treatment for ankle instability.

  5. Microstructure, mechanical properties, bio-corrosion properties and antibacterial properties of Ti–Ag sintered alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Mian [Key Lab. for Anisotropy and Texture of Materials, Education Ministry of China, Northeastern University, Shenyang 110819 (China); Zhang, Erlin, E-mail: zhangel@atm.neu.edu.cn [Key Lab. for Anisotropy and Texture of Materials, Education Ministry of China, Northeastern University, Shenyang 110819 (China); Zhang, Lan [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China)

    2016-05-01

    In this research, Ag element was selected as an antibacterial agent to develop an antibacterial Ti–Ag alloy by a powder metallurgy. The microstructure, phase constitution, mechanical properties, corrosion resistance and antibacterial properties of the Ti–Ag sintered alloys have been systematically studied by X-ray diffraction (XRD), scanning electron microscope (SEM), compressive test, electrochemical measurements and antibacterial test. The effects of the Ag powder size and the Ag content on the antibacterial property and mechanical property as well as the anticorrosion property have been investigated. The microstructure results have shown that Ti–Ag phase, residual pure Ag and Ti were the mainly phases in Ti–Ag(S75) sintered alloy while Ti{sub 2}Ag was synthesized in Ti–Ag(S10) sintered alloy. The mechanical test indicated that Ti–Ag sintered alloy showed a much higher hardness and the compressive yield strength than cp-Ti but the mechanical properties were slightly reduced with the increase of Ag content. Electrochemical results showed that Ag powder size had a significant effect on the corrosion resistance of Ti–Ag sintered alloy. Ag content increased the corrosion resistance in a dose dependent way under a homogeneous microstructure. Antibacterial tests have demonstrated that antibacterial Ti–Ag alloy was successfully prepared. It was also shown that the Ag powder particle size and the Ag content influenced the antibacterial activity seriously. The reduction in the Ag powder size was benefit to the improvement in the antibacterial property and the Ag content has to be at least 3 wt.% in order to obtain a strong and stable antibacterial activity against Staphylococcus aureus bacteria. The bacterial mechanism was thought to be related to the Ti{sub 2}Ag and its distribution. - Highlights: • Ti–Ag alloy with up to 99% antibacterial rate was developed by powder metallurgy. • The effects of the Ag powder size and the Ag content on the

  6. Mechanical properties determination of AM components

    Science.gov (United States)

    Dzugan, J.; Sibr, M.; Konopík, P.; Procházka, R.; Rund, M.

    2017-02-01

    Characterisation of engineering materials and components is a crucial part for design and save service life utilization. Due to components processing technologies and exploitation conditions local properties can significantly vary from location to location over larger components as well as over small material volumes with gradual material changes such as welds, coatings or additively manufactured parts. The current paper is dealing with local properties characterisation for additively manufacture (AM) components by micro tensile test (M-TT). Components produced by additive manufacturing techniques yield properties variation in dependence of the considered location within the component regarding to direction in relation to deposition process. Properties vary over the thickness, length, angle or contacts with the supporting structures necessary for a successful components production by additive manufacturing techniques. The properties differences are mainly related to varying heating/reheating and cooling conditions at various locations of usually very complex parts produced mainly by these technologies. The standard testing procedures fail to characterize such local properties of complex shaped objects due to large size requirements on specimens. Therefore, new techniques have to be established for such detailed local characterizations. Results of miniaturized tensile tests application for local properties and orientations are shown here.

  7. Clinical aspects of tendon healing

    NARCIS (Netherlands)

    J.C.H.M. van der Meulen (Jacques)

    1974-01-01

    textabstractWe know that healing of a tendon wound takes place by an invasion of fibreblasts from the surrounding tissues; the tendon itself has no intrinsic healing capacity. lt was Potenza (1962) who proved that a traumatic suture of the tendons within their sheath is followed by disintegration of

  8. The tendon-to-bone attachment: Unification through disarray

    Science.gov (United States)

    Genin, Guy M.; Thomopoulos, Stavros

    2017-06-01

    High-resolution imaging, composition analysis and mechanical testing reveal a disordered transitional material within the Achilles tendon-to-bone attachment, structured as a fibrous network to enable force transfer and maximize structural integrity.

  9. Sex Hormones and Tendon

    DEFF Research Database (Denmark)

    Hansen, Mette; Kjaer, Michael

    2016-01-01

    The risk of overuse and traumatic tendon and ligament injuries differ between women and men. Part of this gender difference in injury risk is probably explained by sex hormonal differences which are specifically distinct during the sexual maturation in the teenage years and during young adulthood....... The effects of the separate sex hormones are not fully elucidated. However, in women, the presence of estrogen in contrast to very low estrogen levels may be beneficial during regular loading of the tissue or during recovering after an injury, as estrogen can enhance tendon collagen synthesis rate. Yet...

  10. Open Achilles tendon lacerations.

    Science.gov (United States)

    Said, M Nader; Al Ateeq Al Dosari, Mohamed; Al Subaii, Nasser; Kawas, Alaa; Al Mas, Ali; Al Ser, Yaser; Abuodeh, Yousef; Shakil, Malik; Habash, Ali; Mukhter, Khalid

    2015-04-01

    In contrast to closed Achilles tendon ruptures, open injuries are rarely reported in the literature. This paper provides information about open Achilles tendon wounds that are eventually seen in the Middle East. The reporting unit, Hamad Medical Corporation, is one of the biggest trauma centers in the Gulf area and the major health provider in Qatar. This is a retrospective study including patients admitted and operated for open Achilles tendon injuries between January 2011 and December 2013. Two hundred and five cases of open Achilles tendon lacerations were operated in Hamad General Hospital in this period. Forty-eight cases showed partial injuries, and the remaining are complete tendons cut. In the same period, fifty-one closed ruptured Achilles tendons were operated in the same trauma unit. In the majority of cases, the open injury resulted from a slip in the floor-leveled traditional toilette seats. Local damage to the toilette seats resulted in sharp edges causing the laceration of the heel if the patient was slipping over the wet floor. This occurrence is the cause in the vast majority of the cases. Wounds were located 1-5 cm proximal to tendon insertion. Standard treatment principles were applied. This included thorough irrigation in the emergency room, intravenous antibiotics, surgical debridement and primary repair within 24 h. Patients were kept in the hospital 1-7 days for intravenous antibiotics and possible dressing changes. Postoperatively below knee slabs were applied in the majority of patients and were kept for about 4 weeks followed by gradual weight bearing and range of motion exercises. Outpatients follow up in 1-2 weeks. Further follow-up visits at around 2-, 4-, 8- and 12-week intervals until complete wound healing and satisfactory rehabilitation outcome. Sixteen cases needed a second procedure. A high incidence of Achilles tendon open injuries is reported. This seems to be related to partially damaged floor-level toilettes in the

  11. The development of collagen-GAG scaffold-membrane composites for tendon tissue engineering.

    Science.gov (United States)

    Caliari, Steven R; Ramirez, Manuel A; Harley, Brendan A C

    2011-12-01

    Current tissue engineering approaches for tendon defects require improved biomaterials to balance microstructural and mechanical design criteria. Collagen-glycosaminoglycan (CG) scaffolds have shown considerable success as in vivo regenerative templates and in vitro constructs to study cell behavior. While these scaffolds possess many advantageous qualities, their mechanical properties are typically orders of magnitude lower than orthopedic tissues such as tendon. Taking inspiration from mechanically efficient core-shell composites in nature such as plant stems and porcupine quills, we have created core-shell CG composites that display high bioactivity and improved mechanical integrity. These composites feature integration of a low density, anisotropic CG scaffold core with a high density, CG membrane shell. CG membranes were fabricated via an evaporative process that allowed separate tuning of membrane thickness and elastic moduli and were found to be isotropic in-plane. The membranes were then integrated with an anisotropic CG scaffold core via freeze-drying and subsequent crosslinking. Increasing the relative thickness of the CG membrane shell was shown to increase composite tensile elastic modulus by as much as a factor of 36 in a manner consistent with predictions from layered composites theory. CG scaffold-membrane composites were found to support tendon cell viability, proliferation, and metabolic activity in vitro, suggesting they maintain sufficient permeability while demonstrating improved mechanical strength. This work suggests an effective, biomimetic approach for balancing strength and bioactivity requirements of porous scaffolds for tissue engineering. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Expression, content, and localization of insulin-like growth factor I in human achilles tendon

    DEFF Research Database (Denmark)

    Olesen, Jens L; Heinemeier, Katja M; Langberg, Henning

    2006-01-01

    In animals insulin-like growth factor I (IGF-I) stimulates collagen production by fibroblasts and is expressed in tendons together with its binding protein 4 (IGFBP-4). However, the presence of IGF-I and IGFBP-4 in human tendon tissue is not described. Tissue IGF-I content was examined by immunof...... the tendon fibroblasts and that mRNA for IGF-I and IGFBP-4 can be determined in human tendon tissue. The present study adds support for the roles of IGF-I and IGFBP-4 in the regulation of tendon adaptive responses to mechanical loading....

  13. Determination of Mechanical Properties of Microcapsules

    NARCIS (Netherlands)

    Sagis, L.M.C.

    2015-01-01

    Mechanical characterization methods can be important tools in optimizing the design of an encapsulation system. Food microcapsules can be subjected to considerable shear and extensional forces during their life cycle, and the shell of the capsules needs to be designed with sufficient mechanical

  14. Wave-Mechanical Properties of Stationary States.

    Science.gov (United States)

    Holden, Alan

    This monograph is a review of the quantum mechanical concepts presented in two other monographs, "The Nature of Atoms" and "Bonds Between Atoms," by the same author. It is assumed the reader is familiar with these ideas. The monograph sketches only those aspects of quantum mechanics that are of most direct use in picturing and calculating the…

  15. Microstructure and Mechanical Properties of a Laser Treated Al Alloy

    NARCIS (Netherlands)

    Noordhuis, J.; Hosson, J.Th.M. De

    An Al-Cu-Mg alloy, Al 2024-T3, was exposed to laser treatments at various scan velocities. In this paper the microstructural features and mechanical properties are reported. As far as the mechanical property is concerned a striking observation is a minimum in the hardness value at a laser scan

  16. Microstructure and mechanical properties of laser treated aluminium alloys

    NARCIS (Netherlands)

    deHosson, JTM; vanOtterloo, LDM; Noordhuis, J; Mazumder, J; Conde, O; Villar, R; Steen, W

    1996-01-01

    Al-Cu alloys and an Al-Cu-Mg alloy, Al 2024-T3, were exposed to laser treatments at various scan velocities. In this paper the microstructural features and mechanical properties are reported. As far as the mechanical property of the Al-Cu-Mg alloy is concerned a striking observation is a minimum in

  17. Mechanical properties of natural fibre reinforced polymer composites

    Indian Academy of Sciences (India)

    In the present communication, a study on the synthesis and mechanical properties of new series of green composites involving Hibiscus sabdariffa fibre as a reinforcing material in urea–formaldehyde (UF) resin based polymer matrix has been reported. Static mechanical properties of randomly oriented intimately mixed ...

  18. Investigation of the physical and mechanical properties of Shea Tree ...

    African Journals Online (AJOL)

    This study investigated the physical and mechanical properties of Shea Tree timber (V. paradoxa) for structural use obtained at different areas of Kwara State, Nigeria. Physical properties of the samples like moisture content, specific gravity and density was evaluated and the mechanical tests were tensile strength, modulus ...

  19. Role of Interfaces in Mechanical Properties of Polycrystalline Materials

    Indian Academy of Sciences (India)

    Table of contents. Role of Interfaces in Mechanical Properties of Polycrystalline Materials · Slide 2 · Slide 3 · Slide 4 · Mechanical Properties · Slide 6 · Slide 7 · Commercial Applications · Slide 9 · Slide 10 · Grain Boundary Sliding and Slip · Slide 12 · Slide 13 · Role of Grain Boundaries · Superplasticity in Zirconia · Slide 16.

  20. Using nano-indentation and microscopy to obtain mechanical properties

    NARCIS (Netherlands)

    Lukovic, M.; Schlangen, E.; Savija, B.; Ye, G.; Copuroglu, O.

    2015-01-01

    Simulation of mechanical behaviour of heterogeneous materials is only possible if the local properties of the components are known. In recent years nano-indentation is being applied on different levels to obtain local mechanical properties. The aim of this paper is to explore various ways to obtain

  1. Selected physical and mechanical properties of moso bamboo (Phyllostachys pubescens)

    Science.gov (United States)

    H.Q. Yu; Z.H. Jiang; C.Y. Hse; T.F. Shupe

    2008-01-01

    Selected physical and mechanical properties of moso bamboo (Phyllostachys pubescens). Selected physical and mechanical properties of 4?6 year old moso bamboo (Phyllostachys pubescens) grown in Zhejiang, China were investigated at different vertical and horizontal positions. Two way analysis of variance and Tukey?s mean comparison...

  2. Effect of oven residence time on mechanical properties in ...

    Indian Academy of Sciences (India)

    P L Ramkumar

    Abstract. In rotational moulding of plastics, improving the mechanical properties without sacrificing the processibility is a challenging task. In this paper, an attempt has been made to investigate the effect of oven residence time on the mechanical properties of the rotationally moulded products made using linear low density.

  3. Muscle-tendon glucose uptake in Achilles tendon rupture and tendinopathy before and after eccentric rehabilitation: Comparative case reports.

    Science.gov (United States)

    Masood, Tahir; Kalliokoski, Kari; Bojsen-Møller, Jens; Finni, Taija

    2016-09-01

    Achilles tendon rupture (ATR) is the most common tendon rupture injury. The consequences of ATR on metabolic activity of the Achilles tendon and ankle plantarflexors are unknown. Furthermore, the effects of eccentric rehabilitation on metabolic activity patterns of Achilles tendon and ankle plantarflexors in ATR patients have not been reported thus far. We present a case study demonstrating glucose uptake (GU) in the Achilles tendon, the triceps surae, and the flexor hallucis longus of a post-surgical ATR patient before and after a 5-month eccentric rehabilitation. At baseline, three months post-surgery, all muscles and Achilles tendon displayed much higher GU in the ATR patient compared to a healthy individual despite lower plantarflexion force. After the rehabilitation, plantarflexion force increased in the operated leg while muscle GU was considerably reduced. The triceps surae muscles showed similar values to the healthy control. When compared to the healthy or a matched patient with Achilles tendon pain after 12 weeks of rehabilitation, Achilles tendon GU levels of ATR patient remained greater after the rehabilitation. Past studies have shown a shift in the metabolic fuel utilization towards glycolysis due to immobilization. Further research, combined with immuno-histological investigation, is needed to fully understand the mechanism behind excessive glucose uptake in ATR cases. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Phonon spectrum, mechanical and thermophysical properties of thorium carbide

    Energy Technology Data Exchange (ETDEWEB)

    Pérez Daroca, D., E-mail: pdaroca@tandar.cnea.gov.ar [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica (Argentina); Consejo Nacional de Investigaciones Cientı´ficas y Técnicas (Argentina); Jaroszewicz, S. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica (Argentina); Instituto de Tecnología Jorge A. Sabato, UNSAM-CNEA (Argentina); Llois, A.M. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica (Argentina); Consejo Nacional de Investigaciones Cientı´ficas y Técnicas (Argentina); Mosca, H.O. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica (Argentina); Instituto de Tecnología Jorge A. Sabato, UNSAM-CNEA (Argentina)

    2013-06-15

    In this work, we study, by means of density functional perturbation theory and the pseudopotential method, mechanical and thermophysical properties of thorium carbide. These properties are derived from the lattice dynamics in the quasi-harmonic approximation. The phonon spectrum of ThC presented in this article, to the best authors’ knowledge, have not been studied, neither experimentally, nor theoretically. We compare mechanical properties, volume thermal expansion and molar specific capacities with previous results and find a very good agreement.

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

    Science.gov (United States)

    Zhao, Heng; Ren, Yupeng; Roth, Elliot J.; Harvey, Richard L.

    2015-01-01

    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 tendon CSA (5%, P = 0.04), decreased tendon stiffness (42%, P 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 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. PMID:25663670

  6. A Biomechanical Analysis of the Interlock Suture and a Modified Kessler-Loop Lock Flexor Tendon Suture

    Directory of Open Access Journals (Sweden)

    Wenfeng Yang

    Full Text Available OBJECTIVE: In this work, we attempted to develop a modified single-knot Kessler-loop lock suture technique and compare the biomechanical properties associated with this single-knot suture technique with those associated with the conventional modified Kessler and interlock suture techniques. METHODS: In this experiment, a total of 18 porcine flexor digitorum profundus tendons were harvested and randomly divided into three groups. The tendons were transected and then repaired using three different techniques, including modified Kessler suture with peritendinous suture, interlock suture with peritendinous suture, and modified Kessler-loop lock suture with peritendinous suture. Times required for suturing were recorded and compared among groups. The groups were also compared with respect to 2-mm gap load, ultimate failure load, and gap at failure. RESULTS: For tendon repair, compared with the conventional modified Kessler suture technique, the interlock and modified Kessler-loop lock suture techniques resulted in significantly improved biomechanical properties. However, there were no significant differences between the interlock and modified Kessler-loop lock techniques with respect to biomechanical properties, gap at failure, and time required. CONCLUSIONS: The interlock and modified Kessler-loop lock techniques for flexor tendon sutures produce similar mechanical characteristics in vitro.

  7. Morphology, crystallization and dynamic mechanical properties of ...

    Indian Academy of Sciences (India)

    Unknown

    unique optical, electric, and magnetic properties. Compared to other traditional materials, nanocomposite has .... The reagents such as sodium metasilicate and hydrochloric acid were analytical pure reagents (AR). ... Sodium metasilicate was dissolved into deionized water at a certain concentration in a reactor equipped ...

  8. Achilles tendon rupture - aftercare

    Science.gov (United States)

    ... will cover your foot and go to your knee. Your toes will be pointing downward. The cast will be changed every 2 to 3 weeks to help stretch your tendon. If you have a leg brace, splint, or boot, it will keep you from ...

  9. Mechanical Properties of EPON 826/DEA Epoxy

    Science.gov (United States)

    2008-07-26

    properties of Epon 826 and Epon 828 , a similar resin, have been studied by several authors (Katz et al. 1980; Enns and Gillham 1983; Truong 1990; Kozey and...on hydrostatic pressure up to 17 MPa. Chen and Zhang (1997) and Chen and Zhou (1998) studied Epon 828 with curing agent T-403 under compressive...2002) Chen, W., Zhang, X.: Dynamic response of Epon 828 /T-403 under multiaxial loading at various temperatures. J. Eng. Mater. Technol. Trans. ASME

  10. Mechanical Properties of Spider Dragline Silk: Humidity, Hysteresis, and Relaxation

    Science.gov (United States)

    Vehoff, T.; Glišović, A.; Schollmeyer, H.; Zippelius, A.; Salditt, T.

    2007-01-01

    Spider silk is well-known for its outstanding mechanical properties. However, there is a significant variation of these properties in literature and studies analyzing large numbers of silk samples to explain these variations are still lacking. To fill this gap, the following work examines the mechanical properties of major ampullate silk based on a large ensemble of threads from Nephila clavipes and Nephila senegalensis. In addition, the effect of relative humidity (RH) on the mechanical properties was quantified. The large effect of RH on the mechanical properties makes it plausible that the variation in the literature values can to a large extent be attributed to changes in RH. Spider silk's most remarkable property—its high tenacity—remains unchanged. In addition, this work also includes hysteresis as well as relaxation measurements. It is found that the relaxation process is well described by a stretched exponential decay. PMID:17766337

  11. Mechanical properties of F82H plates with different thicknesses

    Energy Technology Data Exchange (ETDEWEB)

    Sakasegawa, Hideo, E-mail: sakasegawa.hideo@jaea.go.jp; Tanigawa, Hiroyasu

    2016-11-01

    Highlights: • Mass effect, homogeneity, and anisotropy in mechanical properties were studied. • Thickness dependence of tensile property was not observed. • Thickness dependence of Charpy impact property was observed. • Appropriate mechanical properties were obtained using an electric furnace. - Abstract: Fusion DEMO reactor requires over 11,000 tons of reduced activation ferritic/martensitic steel and it is indispensable to develop the manufacturing technology for producing large-scale components of DEMO blanket with appropriate mechanical properties. This is because mechanical properties are generally degraded with increasing production volume. In this work, we focused mechanical properties of F82H–BA12 heat which was melted in a 20 tons electric arc furnace. Plates with difference thicknesses from 18 to 100 mm{sup t} were made from its ingot through forging and hot-rolling followed by heat treatments. Tensile and Charpy impact tests were then performed on plates focusing on their homogeneity and anisotropy. From the result, their homogeneity and anisotropy were not significant. No obvious differences were observed in tensile properties between the plates with different thicknesses. However, Charpy impact property changed with increasing plate thickness, i.e. the ductile brittle transition temperature of a 100 mm{sup t} thick plate was higher than that of the other thinner plates.

  12. Effective mechanical properties of multilayer nano-heterostructures.

    Science.gov (United States)

    Mukhopadhyay, T; Mahata, A; Adhikari, S; Zaeem, M Asle

    2017-11-17

    Two-dimensional and quasi-two-dimensional materials are important nanostructures because of their exciting electronic, optical, thermal, chemical and mechanical properties. However, a single-layer nanomaterial may not possess a particular property adequately, or multiple desired properties simultaneously. Recently a new trend has emerged to develop nano-heterostructures by assembling multiple monolayers of different nanostructures to achieve various tunable desired properties simultaneously. For example, transition metal dichalcogenides such as MoS2 show promising electronic and piezoelectric properties, but their low mechanical strength is a constraint for practical applications. This barrier can be mitigated by considering graphene-MoS2 heterostructure, as graphene possesses strong mechanical properties. We have developed efficient closed-form expressions for the equivalent elastic properties of such multi-layer hexagonal nano-hetrostructures. Based on these physics-based analytical formulae, mechanical properties are investigated for different heterostructures such as graphene-MoS2, graphene-hBN, graphene-stanene and stanene-MoS2. The proposed formulae will enable efficient characterization of mechanical properties in developing a wide range of application-specific nano-heterostructures.

  13. The effect of acute exercise on collagen turnover in human tendons

    DEFF Research Database (Denmark)

    Mørch, Lina Steinrud; Pingel, Jessica; Boesen, Mikael

    2013-01-01

    Mechanical loading of human tendon stimulates collagen synthesis, but the relationship between acute loading responses and training status of the tendon is not clear. We tested the effect of prolonged load deprivation on the acute loading-induced collagen turnover in human tendons, by applying...... the same absolute load to a relative untrained Achilles tendon (2-week immobilization period prior to acute loading) and a habitually loaded contra-lateral Achilles tendon, respectively, within the same individuals. Eight untrained, healthy males had one lower limb totally immobilized for 2 weeks, whereas...... the contra-lateral leg was used habitually. Following the procedure both Achilles tendons and calf muscles were loaded with the same absolute load during a 1-h treadmill run. Tissue collagen turnover was measured by microdialysis performed post-immobilization but pre-exercise around both Achilles tendons...

  14. Computation methods affect the reported values of in vivo human tendon stiffness.

    Science.gov (United States)

    Pearson, Stephen J; Onambélé, Gladys L

    2012-01-01

    Scientific validity is questionable when findings from studies cannot be used to make sense of physiological and/or biomechanical data. In particular, is the case of in vivo determination of tendon stiffness (K). Here, approaches range from taking the gradient (a) throughout the data range of resting to Maximal Voluntary Contraction (MVC), (b) tangents at individual data points, (c) linear regressions at discrete force levels ((b) and (c) being 'reference standard' as they utilise a number of distinct regions of the Force-Elongation Relationship (FER)). A mathematical model approach is used to develop simple curvilinear FERs as seen when determining tendon mechanical properties, to allow variable calculations of K. To compare variability in K estimates using the various approaches currently seen in the literature. Three FER models were developed, representing low, medium and high K. Values of K were determined and compared using the approaches reported in the literature to estimate the magnitude of the difference between values attained of K. Through mathematical modelling, we demonstrate that the impact on the recorded value of K is substantial: relative to the reference standard methods, computation methods published range from underestimating K by 26% to overestimating it by 51%. This modelling helps by providing a 'scaling factor' through which the between studies variability associated with computational methods differences is minimised. This is especially important where researchers or clinicians require values which are consistent in the context of establishing the 'true' tendon mechanical properties to inform models or materials based on the biological properties of the human tendon. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Changes in elbow joint's musculo-articular mechanical properties do not alter reaching-related action-perception coupling.

    Science.gov (United States)

    Daviaux, Yannick; Deschamps, Thibault; Cornu, Christophe

    2017-04-01

    Perception of action capabilities can be altered by changes in sensorimotor processes, as showed in previous works in populations dealing with regular and pathological sensorimotor deficits. Misestimating changes in performance ability could lead to risky behavior, injury, and/or reduced performance. However, the relationship between sensorimotor processes, the action-perception coupling, and the related anatomical structures is still a matter of debate. We investigated whether changes in the muscle-tendon system's mechanical properties experimentally induced by eccentric contractions could alter the action-perception coupling (APC) in a reaching-to-grasp task, in which the participants estimated the maximal distance they predicted that they would able to reach a glass. Based on their repartition, volunteers performed a conditioning session the first day: a series of isokinetic elbow extension in passive condition (control group, n = 11) or when performing elbow flexors eccentric contractions (eccentric group, n = 11). Performance estimates and actual performances in a reaching-to-grasp task were completed before, and immediately, 24 hours and 48 hours after the conditioning session. Alterations of musculo-articular mechanical properties were assessed through global joint stiffness (joint passive torque through load/unload cycles) and local stiffness (muscle elastography). The results showed that the APC related to reaching-to-grasp performance was not impacted by post-exercise changes in mechanical properties of the musculo-articular system. These findings emphasize the central dimension of sensorimotor processing instead of peripheral structures to investigate the APC for an altered sensorimotor environment.

  16. Mechanical Properties of Aluminum Die-casting Alloys

    Directory of Open Access Journals (Sweden)

    Sun Xiaodong

    2016-01-01

    Full Text Available The effects of strontium addition on the microstructure and mechanical properties of aluminum alloys 380 and 413 are researched. All samples are prepared through high pressure die-casting, and the effect of the sample’s thickness is also compared. The results indicate that the Sr addition can refine the metallographic microstructure of two alloys in different degrees, mainly to eutectic Si phase. The mechanical properties of the two alloys are improved slightly through Sr modification to the thin wall castings. The enhancement of mechanical properties is evident to the thick wall castings.

  17. The mechanical and strength properties of diamond

    Science.gov (United States)

    Field, J. E.

    2012-12-01

    Diamond is an exciting material with many outstanding properties; see, for example Field J E (ed) 1979 The Properties of Diamond (London: Academic) and Field J E (ed) 1992 The Properties of Natural and Synthetic Diamond (London: Academic). It is pre-eminent as a gemstone, an industrial tool and as a material for solid state research. Since natural diamonds grew deep below the Earth's surface before their ejection to mineable levels, they also contain valuable information for geologists. The key to many of diamond's properties is the rigidity of its structure which explains, for example, its exceptional hardness and its high thermal conductivity. Since 1953, it has been possible to grow synthetic diamond. Before then, it was effectively only possible to have natural diamond, with a small number of these found in the vicinity of meteorite impacts. Techniques are now available to grow gem quality synthetic diamonds greater than 1 carat (0.2 g) using high temperatures and pressures (HTHP) similar to those found in nature. However, the costs are high, and the largest commercially available industrial diamonds are about 0.01 carat in weight or about 1 mm in linear dimension. The bulk of synthetic diamonds used industrially are 600 µm or less. Over 75% of diamond used for industrial purposes today is synthetic material. In recent years, there have been two significant developments. The first is the production of composites based on diamond; these materials have a significantly greater toughness than diamond while still maintaining very high hardness and reasonable thermal conductivity. The second is the production at low pressures by metastable growth using chemical vapour deposition techniques. Deposition onto non-diamond substrates was first demonstrated by Spitsyn et al 1981 J. Cryst. Growth 52 219-26 and confirmed by Matsumoto et al 1982 Japan J. Appl. Phys. 21 L183-5. These developments have added further to the versatility of diamond. Two other groups of materials

  18. Mechanical properties of alumina porcelain during heating

    Science.gov (United States)

    Šín, Peter; Podoba, Rudolf; ŠtubÅa, Igor; Trník, Anton

    2014-11-01

    The mechanical strength and Young's modulus of green alumina porcelain (50 wt. % of kaolin, 25 wt. % of Al2O3, and 25 wt. % of feldspar) were measured during heating up to 900 °C and 1100 °C, respectively. To this end, we used the three point-bending method and modulated force thermomechanical analysis (mf-TMA). The loss liberation - of the physically bound water (20 - 250 °C) strengthens the sample and Young's modulus increases its values significantly. The dehydroxylation that takes place in the range of 400 - 650 °C causes a slight decrease in Young's modulus. On the other hand, the mechanical strength slightly increases in this temperature range, although it has a sudden drop at 420 °C. Beyond the dehydroxylation range, above 650 °C, both Young's modulus and mechanical strength increase. Above 950 °C, a sharp increase of Young's modulus is caused by the solid-state sintering and the new structure created by the high-temperature reactions in metakaolinite.

  19. Dependence of Glass Mechanical Properties on Thermal and Pressure History

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Bauchy, Mathieu

    Predicting the properties of new glasses prior to manufacturing is a topic attracting great industrial and scientific interest. Mechanical properties are currently of particular interest given the increasing demand for stronger, thinner, and more flexible glasses in recent years. However, as a non......-equilibrium material, the structure and properties of glass depend not only on its composition, but also on its thermal and pressure histories. Here we review our recent findings regarding the thermal and pressure history dependence of indentation-derived mechanical properties of oxide glasses....

  20. Tendon injuries of the hand

    Science.gov (United States)

    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

  1. Mechanical Properties of Austenitic Stainless Steel Made by Additive Manufacturing.

    Science.gov (United States)

    Luecke, William E; Slotwinski, John A

    2014-01-01

    Using uniaxial tensile and hardness testing, we evaluated the variability and anisotropy of the mechanical properties of an austenitic stainless steel, UNS S17400, manufactured by an additive process, selective laser melting. Like wrought materials, the mechanical properties depend on the orientation introduced by the processing. The recommended stress-relief heat treatment increases the tensile strength, reduces the yield strength, and decreases the extent of the discontinuous yielding. The mechanical properties, assessed by hardness, are very uniform across the build plate, but the stress-relief heat treatment introduced a small non-uniformity that had no correlation to position on the build plate. Analysis of the mechanical property behavior resulted in four conclusions. (1) The within-build and build-to-build tensile properties of the UNS S17400 stainless steel are less repeatable than mature engineering structural alloys, but similar to other structural alloys made by additive manufacturing. (2) The anisotropy of the mechanical properties of the UNS S17400 material of this study is larger than that of mature structural alloys, but is similar to other structural alloys made by additive manufacturing. (3) The tensile mechanical properties of the UNS S17400 material fabricated by selective laser melting are very different from those of wrought, heat-treated 17-4PH stainless steel. (4) The large discontinuous yielding strain in all tests resulted from the formation and propagation of Lüders bands.

  2. A ganglion of the patellar tendon in patellar tendon-lateral femoral condyle friction syndrome.

    Science.gov (United States)

    Touraine, Sébastien; Lagadec, Matthieu; Petrover, David; Genah, Idan; Parlier-Cuau, Caroline; Bousson, Valérie; Laredo, Jean-Denis

    2013-09-01

    Intratendinous ganglia are rare. We report the case of a sedentary woman with chronic mechanical anterolateral pain of the knee and an extensive ganglion of the patellar tendon as indicated on magnetic resonance (MR) and ultrasound (US) examinations. There was evidence of a high-riding patella, patellar malalignment and patellar tendon-lateral femoral condyle friction syndrome with significantly close contact between the patellar tendon and the lateral facet of the femoral trochlea. The ultrasound-guided aspiration of the ganglion enabled a localized injection of an anti-inflammatory drug (cortivazol) and the cytopathological examination of the fluid, which confirmed the diagnosis. Clinical improvement was maintained with knee rehabilitation and was satisfactory at follow-up after 1 year. To our knowledge, we report the first case of a ganglion of the patellar tendon subsequent to patellar tendon-lateral femoral condyle friction syndrome. We found that this case was illustrative of mucoid degeneration in connective tissue due to chronic repetitive microtraumas. Additionally, this case provided the opportunity to discuss the management of this condition in a sedentary individual with a high-riding patella and patellar malalignment.

  3. Mechanical Properties of Individual Microgel Particles

    Science.gov (United States)

    Hashmi, Sara; Dufresne, Eric

    2009-03-01

    Microgels are important materials for both basic science and engineering and have wide applications from the study of phase transitions to the delivery of drugs. These micron and sub-micron particles, made of hydrogel materials, respond to solvent conditions. The most common microgels are environmentally sensitive, responding to temperature and pH. Our material of interest, poly(N-isopropylacrylamide) or NIPAM, undergoes a deswelling transition above a critical temperature. The deswelling behavior of this polymeric material has been thoroughly studied in ensemble microgel systems as well as in bulk hydrogel samples. We present measurements of the elastic properties of single microgel particles using atomic force microscopy. We observe a stiffening of the Young's modulus by an order of magnitude at temperatures well above the transition, where the cross-linked polymer network has fully collapsed. Interestingly, near the transition we observe a comparable softening of the material.

  4. Suture materials and suture techniques used in tendon repair.

    Science.gov (United States)

    Ketchum, L D

    1985-02-01

    . The less traumatic suture techniques facilitate closure of the tendon sheath, which not only acts as a mechanical barrier to the ingrowth of extrasheath adhesion, which produces fibroblasts, but also re-establishes the continuity of the synovial fluid system, which is a major source of nutrition to the tendon. The healing tendon then can be thought of as a delicate structure, one not to be overmanipulated, traumatized, strangulated, or stretched.(ABSTRACT TRUNCATED AT 400 WORDS)

  5. Interrelationships between electrical, mechanical and hydration properties of cortical bone.

    Science.gov (United States)

    Unal, Mustafa; Cingoz, Fatih; Bagcioglu, Cevat; Sozer, Yilmaz; Akkus, Ozan

    2018-01-01

    Interrelationship between electrical and mechanical properties of cortical bone and the role of bone composition in this interrelationship are not comprehensively investigated to date. This study aimed to investigate associations of electrical properties (i.e., specific impedance, dielectric constant, and conductivity) with mechanical properties (i.e., toughness, strength and elastic modulus) of wet and sequentially dehydrated cortical bone. Bovine cortical bone samples (N = 24) were subjected to three-point bending test. A sequential heat treatment protocol ensued to tease out contributions of unbound water and bound water. Demineralization was performed to understand contributions of organic matrix and the mineral phase to the electrical properties of cortical bone. Raman-spectroscopy based water measurement was used to investigate involvement of collagen- and mineral-bound water in the electrical properties. Our results showed statistically significant correlations between electrical and mechanical properties of cortical bone. Toughness and ultimate strength were negatively correlated with impedance and positively correlated with conductivity and dielectric constant. The highest correlations between electrical and mechanical properties of cortical bone were typically found at the frequencies of 0.2, 0.5 and 1MHz. The electrical properties of bone changed significantly as a result of sequential dehydration, indicating that unbound and bound water compartments are the key determinants of the electrical properties. Comparison of porosity matched bone samples with high and low amount of bound water showed that bound water compartments may have an independent role in determining electrical properties of cortical bone. Furthermore, the results indicated that collagen and mineral-bound water may contribute differentially to the electrical properties of a bone. In the overall, our results suggest that electrical properties of cortical bone may be used to assess bone

  6. Mechanical Properties of Plug Welds after Micro-Jet Cooling

    Directory of Open Access Journals (Sweden)

    Hadryś D.

    2016-12-01

    Full Text Available New technology of micro-jet welding could be regarded as a new way to improve mechanical properties of plug welds. The main purpose of that paper was analyzing of mechanical properties of plug welds made by MIG welding method with micro-jet cooling. The main way for it was comparison of plug welds made by MIG welding method with micro-jet cooling and plug welds made by ordinary MIG welding method. It is interesting for steel because higher amount of acicular ferrite (AF in weld metal deposit (WMD is obtained in MIG welding method with micro-jet cooling in relation to ordinary MIG welding method. This article presents the influence of the cooling medium and the number of micro-jet streams on mechanical properties of the welded joint. Mechanical properties were described by force which is necessary to destroy weld joint.

  7. Mechanical Properties of Austenitic Stainless Steel Made by Additive Manufacturing

    National Research Council Canada - National Science Library

    Luecke, William E; Slotwinski, John A

    2014-01-01

    Using uniaxial tensile and hardness testing, we evaluated the variability and anisotropy of the mechanical properties of an austenitic stainless steel, UNS S17400, manufactured by an additive process...

  8. Resource Letter MPF-1: Mechanical Properties of Fluids

    Science.gov (United States)

    Stanley, R. C.

    1974-01-01

    Presents an annotated bibliography concerning the mechanical properties of fluids, including topics for use at elementary, secondary, undergraduate, and graduate levels. Indicates that the material can particularly help college physicists in improving course contents in specified fields of physics. (CC)

  9. Mechanical properties of plastics predetermined by empirical method

    Science.gov (United States)

    Lohr, J. J.; Parker, J. A.

    1964-01-01

    To predetermine the mechanical properties of rigid plastics as a function of plasticizer content and composition, a set of equations has been empirically derived. These relate strain rate, yield stress, temperature, and weight fraction of the plasticizer.

  10. Synthesis, growth, optical, mechanical and electrical properties of L ...

    Indian Academy of Sciences (India)

    Ne laser source. Mechanical property of the crystal was determined by Vickers hardness tester. The frequency and temperature dependence of dielectric constant (r), dielectric loss (tan ) and a.c. conductivity (ac) were also measured.

  11. Role of Interfaces in Mechanical Properties of Polycrystalline Materials

    Indian Academy of Sciences (India)

    Role of Interfaces in Mechanical Properties of Polycrystalline Materials. Atul H. Chokshi; Department of Metallurgy; Indian Institute of Science; Bangalore 560 012; E-mail: achokshi@met.iisc.ernet.in.

  12. Mechanical Properties of Stainless Steel Cellular Materials with Polyurethane

    National Research Council Canada - National Science Library

    KISHIMOTO, Satoshi; SHIMIZU, Toru; NAITO, Kimiyoshi; KAGAWA, Yutaka

    2011-01-01

    .... The mechanical properties of this material were measured. The results of the compressive tests showed that the stainless steel cellular material containing the polyurethane has different stress-strain curves from that without any polymer...

  13. Densely crosslinked polycarbosiloxanes .2. Thermal and mechanical properties

    NARCIS (Netherlands)

    Flipsen, T.A C; Derks, R.; van der Vegt, H.A.; Stenekes, R.; Pennings, A.J; Hadziioannou, G

    1997-01-01

    The thermal and mechanical properties of two densely crosslinked polycarbosiloxane systems were investigated in relation to the molecular structure. The networks were prepared from functional branched prepolymers and crosslinked via a hydrosilylation curing reaction. The prepolymers having only

  14. effects of sulphur addition on addition on and mechanical properties

    African Journals Online (AJOL)

    User

    234-8034714355. 8034714355. 1. EFFECTS OF SULPHUR ADDITION ON. ADDITION ON. 2. AND MECHANICAL PROPERTIES O. 3. 4. C. W. Onyia. 5. 1DEPT. OF METALLURGICAL AND MATERIALS. 6. 2, 4DEPT. OF METALLURGICAL ...

  15. Mechanical properties of short doughs and their corresponding biscuits

    NARCIS (Netherlands)

    Baltsavias, A.

    1996-01-01


    The mechanical properties of short doughs of various composition were determined in small amplitude oscillatory experiments and in uniaxial compression. Regardless of composition, the linear region was very limited; beyond that, pronounced yielding and flow occurred. Conductimetry was

  16. Miscellaneous conditions of tendons, tendon sheaths, and ligaments.

    Science.gov (United States)

    Dyson, S J; Dik, K J

    1995-08-01

    The use of diagnostic ultrasonography has greatly enhances our ability to diagnose injuries of tendons and tendon sheaths that were previously either unrecognized or poorly understood. For may of these injuries, there is currently only a small amount of follow-up data. This article considers injuries of the deep digital flexor tendon and its accessory ligament, the carpal tunnel syndrome soft tissue swellings on the dorsal aspect of the carpus, intertubercular (bicipital) bursitis and bicipital tendinitis, injuries of the gastrocnemius tendon, common calcaneal tendinitis, rupture of peroneus (fibularis tertius) and ligaments injuries of the back.

  17. Mechanism of Intellectual Property Management in Engineering Companies

    OpenAIRE

    Pukhalskaya Anastasiya P.

    2013-01-01

    The article offers a mechanism of intellectual property management in engineering companies, which envisages synthesis of a system of opinions upon provision of management with existing objects of intellectual property (IP) in a company with the aim to attract them into economic turnover and increase efficiency of their use. Application of the described mechanism of IP management would provide a company with realisation of monopoly rights on results of intellectual activity and would facilita...

  18. Primate dietary ecology in the context of food mechanical properties.

    Science.gov (United States)

    Coiner-Collier, Susan; Scott, Robert S; Chalk-Wilayto, Janine; Cheyne, Susan M; Constantino, Paul; Dominy, Nathaniel J; Elgart, Alison A; Glowacka, Halszka; Loyola, Laura C; Ossi-Lupo, Kerry; Raguet-Schofield, Melissa; Talebi, Mauricio G; Sala, Enrico A; Sieradzy, Pawel; Taylor, Andrea B; Vinyard, Christopher J; Wright, Barth W; Yamashita, Nayuta; Lucas, Peter W; Vogel, Erin R

    2016-09-01

    Substantial variation exists in the mechanical properties of foods consumed by primate species. This variation is known to influence food selection and ingestion among non-human primates, yet no large-scale comparative study has examined the relationships between food mechanical properties and feeding strategies. Here, we present comparative data on the Young's modulus and fracture toughness of natural foods in the diets of 31 primate species. We use these data to examine the relationships between food mechanical properties and dietary quality, body mass, and feeding time. We also examine the relationship between food mechanical properties and categorical concepts of diet that are often used to infer food mechanical properties. We found that traditional dietary categories, such as folivory and frugivory, did not faithfully track food mechanical properties. Additionally, our estimate of dietary quality was not significantly correlated with either toughness or Young's modulus. We found a complex relationship among food mechanical properties, body mass, and feeding time, with a potential interaction between median toughness and body mass. The relationship between mean toughness and feeding time is straightforward: feeding time increases as toughness increases. However, when considering median toughness, the relationship with feeding time may depend upon body mass, such that smaller primates increase their feeding time in response to an increase in median dietary toughness, whereas larger primates may feed for shorter periods of time as toughness increases. Our results emphasize the need for additional studies quantifying the mechanical and chemical properties of primate diets so that they may be meaningfully compared to research on feeding behavior and jaw morphology. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. MRI of the Achilles tendon

    Energy Technology Data Exchange (ETDEWEB)

    Naegele, M.; Lienemann, A.; Hahn, D.; Lissner, J.; Boehm, P.

    1987-06-01

    The Achilles tendon and preachillar space of 30 patients was studied by MRI. A surface coil (Helmholtz' principle) was applied and all patients were examined with a superconducting magnet operating at 1.0 Tesla field strength. The purpose of the study was to illustrate pathological changes of the tendon and the surrounding soft tissue. In 3 cases MRI diagnosed a total rupture of the Achilles tendon. Furthermore, the strain of the tendon and side effects of an inflammatory process could be demonstrated. The use of a surface coil yields a high resolution of the normal anatomy of the region and of the pathological changes of the tendon and the surrounding soft tissue structures. The advantages of MRI for Achilles tendon diagnostics against competitive modalities are 1) excellent soft tissue contrast, 2) multiplanar imaging, 3) as well as exact delineation and visualisation of the lesion.

  20. Mechanical and Morphological Properties of Nano Filler Polyester Composites

    Directory of Open Access Journals (Sweden)

    Bonnia Noor Najmi

    2016-01-01

    Full Text Available This research is focusing on mechanical and morphological properties of unsaturated polyester (UP reinforced with two different types of filler which is nano size clay Cloisite 30B (C30B and Carbon Black (CB. Samples were fabricated via hand lay-up and open molding technique. Percentages of Cloisite 30B & Carbon Black (CB used vary from 0, 2, 4, 6, 8 and 10 wt%. The mechanical properties were evaluated by impact, flexural and hardness testing. Result shows that the mechanical strength of C30B was better compare to CB filled composite. The combination of UP with C30B helps to improve the properties due to the high surface area of nanosize filler in the matrix. The result shows that increasing of filler content had increased mechanical properties of composites. Optimum percentage represent good mechanical properties are 4% for both fillers. SEM images showed that rough surface image indicate to agglomeration of filler in the matrix for CB sample and smooth surface image on C30B sample indicate to homogenous blending between filler and matrix polyester. SEM images proved that mechanical properties result indicate that C30B polyester composite is a good reinforcement compare to CB polyester composite.

  1. A fully automated system for measuring cellular mechanical properties.

    Science.gov (United States)

    Wang, Zhibo; Liu, Lianqing; Wang, Yuechao; Xi, Ning; Dong, Zaili; Li, Mi; Yuan, Shuai

    2012-12-01

    As a novel effective label-free biomarker, the mechanical properties of cells have become increasingly important. However, the current methods of mapping cellular mechanical properties are mostly carried out manually, resulting in measurements that are time-consuming with low efficiency. In this article, a fully automated system of measuring the mechanical properties of cells based on atomic force microscopy (AFM) is proposed. In this system, the cells are recognized using an image-processing method and the relative position of the cell, and the AFM tip is accurately calibrated by the local scan method, meaning that the mechanical properties of cells can be measured sequentially without performing the step of AFM imaging. In addition, with the implementation of the automation, the high-throughput measurement of cellular mechanical properties can be performed rapidly. The capability of our system is validated on Raji cells, and the results indicate that the measurement rate of our system is 26 times faster than that of the traditional manual method, providing the technology for high-throughput measurement of cellular mechanical properties.

  2. Mechanical properties of short-flax-fibre reinforced compounds

    NARCIS (Netherlands)

    Bos, H.L.; Müssig, J.; Oever, van den M.J.A.

    2006-01-01

    The mechanical properties of flax/polypropylene compounds, manufactured both with a batch kneading and an extrusion process were determined and compared with the properties of Natural fibre Mat Thermoplastic (NMT) composites. The fibre length and width distributions of the fibres from the compounds

  3. Ultrasonic investigation of mechanical properties of double base rocket propellants

    NARCIS (Netherlands)

    Schroeff, J.A. van der; Boer, R.S. de

    1976-01-01

    For a series of double base rocket propellants and for poly-methylmethacrylate (PMMA) the longitudinal and transverse sound wave velocities are measured at a frequency of 0.351 MHz in t h e temperature range of −40°C to +60°C. The relations between these acoustic properties and mechanical properties

  4. The Determination of Some Mechanical Properties of Scheffe's ...

    African Journals Online (AJOL)

    The work determined some mechanical properties of fresh and matured concrete. These properties include Slump, Compressive Strength, Static modulus of elasticity and Modulus of rigidity. It applied Scheffe's optimization theory to determine the ratio of the combined constituents of the concrete mix. The results showed that ...

  5. Optical and mechanical properties of diamond like carbon films ...

    Indian Academy of Sciences (India)

    DLC films deposited at three different bias voltages (–60 V, –100 V and –150 V) were characterized by FTIR, Raman spectroscopy and spectroscopic ellipsometry to study the variation in the bonding and optical properties of the deposited coatings with process parameters. The mechanical properties such as hardness and ...

  6. Investigation of tribological and mechanical properties of metal ...

    Indian Academy of Sciences (India)

    Administrator

    2009-09-02

    Sep 2, 2009 ... this study, tribological and mechanical properties of these journal bearings manufactured by metals were ..... Design 28. 1889. Ünlü B S 2004 Determination of usability of boronized ferrous based materials as bearing and tribological properties in journal bearings, PhD thesis, Celal Bayar University,.

  7. Prediction of mechanical properties for hexagonal boron nitride nanosheets using molecular mechanics model

    Science.gov (United States)

    Natsuki, Toshiaki; Natsuki, Jun

    2017-04-01

    Mechanical behaviors of nanomaterials are not easy to be evaluated in the laboratory because of their extremely small size and difficulty controlling. Thus, a suitable model for the estimation of the mechanical properties for nanomaterials becomes very important. In this study, the elastic properties of boron nitride (BN) nanosheets, including the elastic modulus, the shear modulus, and the Poisson's ratio, are predicted using a molecular mechanics model. The molecular mechanics force filed is established to directly incorporate the Morse potential function into the constitutive model of nanostructures. According to the molecular mechanics model, the chirality effect of hexagonal BN nanosheets on the elastic modulus is investigated through a closed-form solution. The simulated result shows that BN nanosheets exhibit an isotropic elastic property. The present analysis yields a set of very simple formulas and is able to be served as a good approximation on the mechanical properties for the BN nanosheets.

  8. Prediction of mechanical properties for hexagonal boron nitride nanosheets using molecular mechanics model

    Energy Technology Data Exchange (ETDEWEB)

    Natsuki, Toshiaki [Shinshu University, Faculty of Textile Science and Technology, Ueda (Japan); Shinshu University, Institute of Carbon Science and Technology, Nagano (Japan); Natsuki, Jun [Shinshu University, Institute of Carbon Science and Technology, Nagano (Japan)

    2017-04-15

    Mechanical behaviors of nanomaterials are not easy to be evaluated in the laboratory because of their extremely small size and difficulty controlling. Thus, a suitable model for the estimation of the mechanical properties for nanomaterials becomes very important. In this study, the elastic properties of boron nitride (BN) nanosheets, including the elastic modulus, the shear modulus, and the Poisson's ratio, are predicted using a molecular mechanics model. The molecular mechanics force filed is established to directly incorporate the Morse potential function into the constitutive model of nanostructures. According to the molecular mechanics model, the chirality effect of hexagonal BN nanosheets on the elastic modulus is investigated through a closed-form solution. The simulated result shows that BN nanosheets exhibit an isotropic elastic property. The present analysis yields a set of very simple formulas and is able to be served as a good approximation on the mechanical properties for the BN nanosheets. (orig.)

  9. Mechanical and Thermophysical Properties of Cerium Monopnictides

    Science.gov (United States)

    Bhalla, Vyoma; Singh, Devraj; Jain, S. K.

    2016-03-01

    The ultrasonic attenuation due to phonon-phonon interaction, thermoelastic relaxation and dislocation damping mechanisms has been investigated in cerium monopnictides CeX (X: N, P, As, Sb and Bi) for longitudinal and shear waves along {< }100{rangle }, {< }110{rangle } and {< }111{rangle } directions. The second- and third-order elastic constants of CeX have also been computed in the temperature range 0 K to 500 K using Coulomb and Born-Mayer potential upto second nearest neighbours. The computed values of these elastic constants have been applied to find out Young's moduli, bulk moduli, Breazeale's non-linearity parameters, Zener anisotropy, ultrasonic velocity, ultrasonic Grüneisen parameter, thermal relaxation time, acoustic coupling constants and ultrasonic attenuation. The fracture/toughness ratio is less than 1.75, which shows that the chosen materials are brittle in nature as found for other monopnictides. The drag coefficient acting on the motion of screw and edge dislocations due to shear and compressional phonon viscosities of the lattice have also been evaluated for both the longitudinal and shear waves. The thermoelastic loss and dislocation damping loss are negligible in comparison to loss due to Akhieser damping (phonon-phonon interaction). The obtained results for CeX are in qualitative agreement with other semi-metallic monopnictides.

  10. Physical and mechanical properties of membrane Polyacrylonitrile

    Directory of Open Access Journals (Sweden)

    Mataram Agung

    2017-01-01

    Full Text Available Tensile test is a method used to measure the strength of a material by providing the burden of the opposing forces in a straight line. This experiment used to measure a material’s mechanical strength against a static force which is given slowly. This study discusses on the tensile strength polyacrylonitrile (PAN membranes made in three variations of the specimen with a mixed composition of different PAN 15%, 17.5%, 20%, in weight. The membrane was created using Sigma Aldrich Polyacrylonitile of polymer fibers and N,N-Dimethylformamide (DMF as solvent. The process began by mixing the two materials using a magnetic stirrer for 6 hours until the solution is assumed to be homogeneous. The solution wass stored in the bottle airtight and allowed to stand for 24 hours for the next printing. The membrane was keep in storage in tubes desiccator until its water content reduced, then the test can be done. In this study, a machine adhesion terring strength tester was used conducting Strength Test at a speed of 5 mm/min. The test results showed an increase in the value of 359 kPa on the composition of 15%, 473 kPa on the composition of 17.5%, and 653 kPa for the composition of a mixture of 20%.

  11. Mechanical properties of lanthanum and yttrium chromites

    Energy Technology Data Exchange (ETDEWEB)

    Paulik, S.W.; Armstrong, T.R. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-12-31

    In an operating high-temperature (1000{degrees}C) solid oxide fuel cell (SOFC), the interconnect separates the fuel (P(O{sub 2}){approx}10{sup -16} atm) and the oxidant (P(O2){approx}10{sup 0.2} atm), while being electrically conductive and connecting the cells in series. Such severe atmospheric and thermal demands greatly reduce the number of viable candidate materials. Only two materials, acceptor substituted lanthanum chromite and yttrium chromite, meet these severe requirements. In acceptor substituted chromites (Sr{sup 2+} or Ca{sup 2+} for La{sup 3+}), charge compensation is primarily electronic in oxidizing conditions (through the formation of Cr{sup 4+}). Under reducing conditions, ionic charge compensation becomes significant as the lattice becomes oxygen deficient. The formation of oxygen vacancies is accompanied by the reduction of Cr{sup 4+} ions to Cr{sup 3+} and a resultant lattice expansion. The lattice expansion observed in large chemical potential gradients is not desirable and has been found to result in greatly reduced mechanical strength.

  12. High temperature mechanical properties of iron aluminides

    Directory of Open Access Journals (Sweden)

    Morris, D. G.

    2001-04-01

    Full Text Available Considerable attention has been given to the iron aluminide family of intermetallics over the past years since they offer considerable potential as engineering materials for intermediate to high temperature applications, particularly in cases where extreme oxidation or corrosion resistance is required. Despite efforts at alloy development, however, high temperature strength remains low and creep resistance poor. Reasons for the poor high-temperature strength of iron aluminides will be discussed, based on the ordered crystal structure, the dislocation structure found in the material, and the mechanisms of dislocation pinning operating. Alternative ways of improving high temperature strength by microstructural modification and the inclusion of second phase particles will also be considered.

    Durante los últimos años se ha prestado mucha atención a la familia de intermetálicos Fe-Al, puesto que estos constituyen un considerable potencial como materiales de ingeniería en aplicaciones a temperaturas intermedias o altas, sobre todo en casos donde se necesita alta resistencia a la oxidación o corrosión. A pesar del considerable esfuerzo desarrollado para obtener aleaciones con mejores propiedades, su resistencia mecánica a alta temperatura no es muy elevada. Se discutirán los aspectos que contribuyen a la baja resistencia mecánica a temperatura elevada en función de la estructura de dislocaciones y los mecanismos de anclaje que operan en este intermetálico. Se considerarán, también, maneras alternativas para mejorar la resistencia a temperatura elevada mediante la modificación de la microestructura y la incorporación de partículas de segunda fase.

  13. Effect of tomato internal structure on its mechanical properties and ...

    African Journals Online (AJOL)

    ONOS

    2010-03-22

    Mar 22, 2010 ... As different tomatoes have different locular cavities and a particular tomato material is inhomogeneous, the effect of tomato internal structure on its mechanical properties and degree of mechanical damage may be significant during the gripping process with robot fingers. This was studied using the ...

  14. Mechanical property analysis of kenaf–glass fibre reinforced ...

    Indian Academy of Sciences (India)

    Mechanical property analysis of kenaf–glass fibre reinforced polymer composites using finite element analysis. M RAMESH∗ and S NIJANTHAN. Department of Mechanical Engineering, Sri Sai Ram Engineering College, Chennai 600 044, Tamil Nadu, India. MS received 29 June 2015; accepted 29 September 2015.

  15. Mechanical properties of natural fibre reinforced polymer composites

    Indian Academy of Sciences (India)

    Wintec

    In the present communication, a study on the synthesis and mechanical properties of new series of green composites involving .... visual similarity. 3. Results and discussion. The importance of static mechanical analysis (SMA) as a tool in the study of the behaviour of polymer biocompo- sites is of paramount importance.

  16. Estimation of mechanical properties of single wall carbon nanotubes ...

    Indian Academy of Sciences (India)

    The geometry of CNT is built using a macro that is developed for the finite element analysis software. The finite element model of the CNT is con- structed, appropriate boundary conditions are applied and the behavior of mechanical properties of CNT is studied. Keywords. Molecular mechanics; single wall carbon nanotube; ...

  17. Effect of tomato internal structure on its mechanical properties and ...

    African Journals Online (AJOL)

    ... locular cavities and a particular tomato material is inhomogeneous, the effect of tomato internal structure on its mechanical properties and degree of mechanical damage may be significant during the gripping process with robot fingers. This was studied using the loading-unloading experiment as well as the observation of ...

  18. In vitro indentation to determine the mechanical properties of epidermis

    NARCIS (Netherlands)

    Geerligs, M.; Van Breemen, L.; Peters, G.W.M.; Ackermans, P.A.J.; Baaijens,F.P.T.; Oomens, C.

    2011-01-01

    The lack of understanding of the mechanical behavior of the human skin layers makes the development of drug delivery using microneedles or microjets a challenging task. In particular, the key mechanical properties of the epidermis composed of stratum corneum and viable epidermis, should be better

  19. The role of the synovial fluid and tendon sheath for flexor tendon nutrition. An experimental tracer study on diffusional pathways in dogs.

    Science.gov (United States)

    Lundborg, G; Holm, S; Myrhage, R

    1980-01-01

    Radioactive tracers were used to analyse nutritional mechanisms of flexor tendons of dogs during various experimental conditions. The transport and distribution of methyl glucose in the tendon was analysed 15 min after intravenous injection during the following experimental conditions: (1) normal state--rest; (2) passive mobilization of the tendon; (3) active mobilization of the tendon; (4) exclusion of exposure to synovial fluid-preservation of vascular supply; (5) exclusion of vascular supply--preservation of exposure to synovial fluid. The results indicate that active mobilization gives a significant increase in tracer concentration in the volar part of the tendon, while passive mobilization has no such effect. Diffusional pathways from the synovial fluid plays a major role for transport of tracer into the tendon, while the intrinsic vascular system apparently is of no or minor importance in this respect. The main mechanism for solute transport within the tendon is passive diffusion. Transport of sulphate in the volar part follows a similar pattern as in other avascular tissues and the incorporation of sulphate by the cells is low and comparable to that in articular cartilage. The results support our previous hypothesis that the flexor tendon system physiologically corresponds to a joint, and that the synovial fluid plays an important role for flexor tendon nutrition.

  20. Mechanical Properties and Durability of "Waterless Concrete"

    Science.gov (United States)

    Toutanji, Houssam; Grugel, Richard N.

    2008-01-01

    Waterless concrete consists of molten elementary sulfur and aggregate. The aggregates in lunar environment will be lunar rocks and soil. Sulfur is present on the Moon in Troilite soil (FeS) and by oxidation soil iron and sulfur can be produced. Iron can be used to reinforce the sulfur concrete. Sulfur concrete specimens were cycled between liquid nitrogen (approximately 191 C) and room temperature (approximately 21 C) to simulate exposure to a lunar environment. Cycled and control specimens were subsequently tested in compression at room temperatures (approximately 21 C) and approximately 101 C. Test results showed that due to temperature cycling, compressive strength of cycled specimens was 20% of those non-cycled. Microscopic examination of the fracture surfaces from the cycled samples showed clear de-bonding of the sulfur from the aggregate material whereas it was seen well bonded in those non-cycled. This reduction in strength can be attributed to the large differences in thermal coefficients of expansion of the materials constituting the concrete which promoted cracking. Similar sulfur concrete mixtures were strengthened with short and long glass fibers. The glass fibers from lunar regolith simulant was melted in a 25 cc Pt-Rh crucible in a Sybron Thermoline high temperature MoSi2 furnace at melting temperatures of 1450 to 1600 C for times of 30 min to 1 hour. Glass fibers were cast from the melt into graphite crucibles and were annealed for a couple of hours at 600 C. Glass fibers and small rods were pulled from the melt. The glass melt wets the ceramic rod and long continuous glass fibers were easily hand drawn. The glass fibers were immediately coated with a protective polymer to maintain the mechanical strength. The glass fibers were used to reinforce sulfur concrete plated to improve the flexural strength of the sulfur concrete. Prisms beams strengthened with glass fibers were tested in 4-point bending test. Beams strengthened with glass fiber showed to

  1. Mineral distributions at the developing tendon enthesis.

    Directory of Open Access Journals (Sweden)

    Andrea G Schwartz

    to endochondral bone formation near the tendon insertion. These conserved and time-varying aspects of interface composition may have important implications for the growth and mechanical stability of the tendon-to-bone attachment throughout development.

  2. Mechanical properties of carbon nanotube/polymer composites

    Science.gov (United States)

    Arash, B.; Wang, Q.; Varadan, V. K.

    2014-01-01

    The remarkable mechanical properties of carbon nanotubes, such as high elastic modulus and tensile strength, make them the most ideal and promising reinforcements in substantially enhancing the mechanical properties of resulting polymer/carbon nanotube composites. It is acknowledged that the mechanical properties of the composites are significantly influenced by interfacial interactions between nanotubes and polymer matrices. The current challenge of the application of nanotubes in the composites is hence to determine the mechanical properties of the interfacial region, which is critical for improving and manufacturing the nanocomposites. In this work, a new method for evaluating the elastic properties of the interfacial region is developed by examining the fracture behavior of carbon nanotube reinforced poly (methyl methacrylate) (PMMA) matrix composites under tension using molecular dynamics simulations. The effects of the aspect ratio of carbon nanotube reinforcements on the elastic properties, i.e. Young's modulus and yield strength, of the interfacial region and the nanotube/polymer composites are investigated. The feasibility of a three-phase micromechanical model in predicting the elastic properties of the nanocomposites is also developed based on the understanding of the interfacial region. PMID:25270167

  3. Chronic alcohol abuse in men alters bone mechanical properties by affecting both tissue mechanical properties and microarchitectural parameters.

    Science.gov (United States)

    Cruel, M; Granke, M; Bosser, C; Audran, M; Hoc, T

    2017-06-01

    Alcohol-induced secondary osteoporosis in men has been characterized by higher fracture prevalence and a modification of bone microarchitecture. Chronic alcohol consumption impairs bone cell activity and results in an increased fragility. A few studies highlighted effects of heavy alcohol consumption on some microarchitectural parameters of trabecular bone. But to date and to our knowledge, micro- and macro-mechanical properties of bone of alcoholic subjects have not been investigated. In the present study, mechanical properties and microarchitecture of trabecular bone samples from the iliac crest of alcoholic male patients (n=15) were analyzed and compared to a control group (n=8). Nanoindentation tests were performed to determine the tissue's micromechanical properties, micro-computed tomography was used to measure microarchitectural parameters, and numerical simulations provided the apparent mechanical properties of the samples. Compared to controls, bone tissue from alcoholic patients exhibited an increase of micromechanical properties at tissue scale, a significant decrease of apparent mechanical properties at sample scale, and significant changes in several microarchitectural parameters. In particular, a crucial role of structure model index (SMI) on mechanical properties was identified. 3D microarchitectural parameters are at least as important as bone volume fraction to predict bone fracture risk in the case of alcoholic patients. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  4. Lithophysal Rock Mass Mechanical Properties of the Repository Host Horizon

    Energy Technology Data Exchange (ETDEWEB)

    D. Rigby

    2004-11-10

    The purpose of this calculation is to develop estimates of key mechanical properties for the lithophysal rock masses of the Topopah Spring Tuff (Tpt) within the repository host horizon, including their uncertainties and spatial variability. The mechanical properties to be characterized include an elastic parameter, Young's modulus, and a strength parameter, uniaxial compressive strength. Since lithophysal porosity is used as a surrogate property to develop the distributions of the mechanical properties, an estimate of the distribution of lithophysal porosity is also developed. The resulting characterizations of rock parameters are important for supporting the subsurface design, developing the preclosure safety analysis, and assessing the postclosure performance of the repository (e.g., drift degradation and modeling of rockfall impacts on engineered barrier system components).

  5. Effect of vitro preservation on mechanical properties of brain tissue

    Science.gov (United States)

    Zhang, Wei; Liu, Yi-fan; Liu, Li-fu; Niu, Ying; Ma, Jian-li; Wu, Cheng-wei

    2017-05-01

    To develop the protective devices for preventing traumatic brain injuries, it requires the accurate characterization of the mechanical properties of brain tissue. For this, it necessary to elucidate the effect of vitro preservation on the mechanical performance of brain tissue as usually the measurements are carried out in vitro. In this paper, the thermal behavior of brain tissue preserved for various period of time was first investigated and the mechanical properties were also measured. Both reveals the deterioration with prolonged preservation duration. The observations of brain tissue slices indicates the brain tissue experiences karyorrhexis and karyorrhexis in sequence, which accounts for the deterioration phenomena.

  6. Mechanical Properties of Composites Used in High-Voltage Applications

    Directory of Open Access Journals (Sweden)

    Andreas Moser

    2016-07-01

    Full Text Available Materials used in high voltage applications have to meet a lot of regulations for their safety and functional usage during their lifetime. For high voltage applications the electrical properties are the most relevant designing criteria. However, the mechanical properties of such materials have rarely been considered for application dimensioning over the last decades. This article gives an overview of composite materials used in high voltage applications and some basic mechanical and thermo-mechanical characterization methods of such materials, including a discussion of influences on practically used epoxy based thermosets.

  7. Mechanical Properties of Isotactic Polypropylene Modified with Thermoplastic Potato Starch

    Science.gov (United States)

    Knitter, M.; Dobrzyńska-Mizera, M.

    2015-05-01

    In this paper selected mechanical properties of isotactic polypropylene (iPP) modified with potato starch have been presented. Thermoplastic starch (TPS) used as a modifier in the study was produced from potato starch modified with glycerol. Isotactic polypropylene/thermoplastic potato starch composites (iPP/TPS) that contained 10, 30, 50 wt.% of modified starch were examined using dynamic mechanical-thermal analysis, static tensile, Brinell hardness, and Charpy impact test. The studies indicated a distinct influence of a filler content on the mechanical properties of composites in comparison with non-modified polypropylene.

  8. Evaluating the Mechanical Properties of Tomato Based on Electrical Conductivity

    Directory of Open Access Journals (Sweden)

    M Ghasemi

    2014-09-01

    Full Text Available Evaluation of mechanical and electrical properties of agricultural products plays an important role in equipment design and optimizing post-harvest operations. Among the crops, tomato and its products are the major processing industries in the world and its economic importance is increasing. Considering the importance of the quality and various post harvesting uses of tomato, the evaluation of mechanical properties including rupture force and deformation and the work done to establish the rupture of two tomato cultivars (Petoearly CH and Newton were studied under penetration test based on the electrical conductivity. These properties were measured at three levels of 1, 3 and 5 days after harvesting. The evaluated mechanical properties of both cultivars were decreased by increasing the storage time. Interaction of cultivar and time were significant at the 1% level, for all mechanical parameters except the deformation failure in both cultivars. The electrical conductivity of both cultivars was decreased by increasing the storage time. Interaction of cultivar and time on the electrical conductivity of both cultivars were significant at the 1% level. Significant relationships were found at the 1% level between electrical conductivity and mechanical properties except for deformation of Petoearly CH cultivar. Among the mechanical parameters, rupture forces and rupture works of both cultivars were highly correlated with the electrical conductivity.

  9. Effects of foot orthoses on Achilles tendon load in recreational runners.

    Science.gov (United States)

    Sinclair, J; Isherwood, J; Taylor, P J

    2014-09-01

    Achilles tendon pathology is a frequently occurring musculoskeletal disorder in runners. Foot orthoses have been shown to reduce the symptoms of pain in runners but their mechanical effects are still not well understood. This study aimed to examine differences in Achilles tendon load when running with and without orthotic intervention. Twelve male runners ran at 4.0 m·s(-1). Ankle joint moments and Achilles tendon forces were compared when running with and without orthotics. The results indicate that running with foot orthotics was associated with significant reductions in Achilles tendon load compared to without orthotics. In addition to providing insight into the mechanical effects of orthotics in runners, the current investigation suggests that via reductions in Achilles tendon load, foot orthoses may serve to reduce the incidence of chronic Achilles tendon pathologies in runners. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Mechanical properties of jennite: A theoretical and experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Juhyuk, E-mail: juhyuk.moon@stonybrook.edu [Civil Engineering Program, Department of Mechanical Engineering, Stony Brook University, NY 11794 (United States); Yoon, Seyoon [School of Engineering, Kings College, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Monteiro, Paulo J.M. [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States)

    2015-05-15

    The objective of this study is to determine the mechanical properties of jennite. To date, several hypotheses have been proposed to predict the structural properties of jennite. For the first time as reported herein, the isothermal bulk modulus of jennite was measured experimentally. Synchrotron-based high-pressure x-ray diffraction experiments were performed to observe the variation of lattice parameters under pressure. First-principles calculations were applied to compare with the experimental results and predict additional structural properties. Accurately measured isothermal bulk modulus herein (K{sub 0} = 64(2) GPa) and the statistical assessment on experimental and theoretical results suggest reliable mechanical properties of shear and Young's modulus, Poisson's ratio, and elastic tensor coefficients. Determination of these fundamental structural properties is the first step toward greater understanding of calcium–silicate–hydrate, as well as provides a sound foundation for forthcoming atomic level simulations.

  11. Tendon and Ligament Regeneration and Repair: Clinical Relevance and Developmental Paradigm

    Science.gov (United States)

    Tuan, Rocky S.

    2014-01-01

    Tendon and ligament (T/L) are dense connective tissues connecting bone to muscle and bone to bone, respectively. Similar to other musculoskeletal tissues, T/L arise from the somitic mesoderm, but they are derived from a recently discovered somitic compartment, the syndetome. The adjacent sclerotome and myotome provide inductive signals to the interposing syndetome, thereby upregulating the expression of the transcription factor Scleraxis, which in turn leads to further tenogenic and ligamentogenic differentiation. These advances in the understanding of T/L development have been sought to provide a knowledge base for improving the healing of T/L injuries, a common clinical challenge due to the intrinsically poor natural healing response. Specifically, the three most common tendon injuries involve tearing of the rotator cuff of the shoulder, the flexor tendon of the hand, and the Achilles tendon. At present, injuries to these tissues are treated by surgical repair and/or conservative approaches, including biophysical modalities such as physical rehabilitation and cryotherapy. Unfortunately, the healing tissue forms fibrovascular scar and possesses inferior mechanical and biochemical properties as compared to native T/L. Therefore, tissue engineers have sought to improve upon the natural healing response by augmenting the injured tissue with cells, scaffolds, bioactive agents, and mechanical stimulation. These strategies show promise, both in vitro and in vivo, for improving T/L healing. However, several challenges remain in restoring full T/L function following injury, including uncertainties over the optimal combination of these biological agents as well how to best deliver tissue engineered elements to the injury site. A greater understanding of the molecular mechanisms involved in T/L development and natural healing, coupled with the capability of producing complex biomaterials to deliver multiple growth factors with high spatiotemporal resolution and specificity

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

    Science.gov (United States)

    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.

  13. Effect of Suture Material and Bone Quality on the Mechanical Properties of Zone I Flexor Tendon–Bone Reattachment With Bone Anchors

    Science.gov (United States)

    Matsuzaki, Hironori; Zaegel, Melissa A.; Gelberman, Richard H.; Silva, Matthew J.

    2015-01-01

    Purpose To compare the initial biomechanical properties of zone I flexor tendon to bone repairs performed using pull-out and anchor techniques and to investigate the effect of bone quality and suture materials on the strength of anchor repairs. Methods Using computed tomography, we measured bone mineral density and cortical thickness of the distal phalanx of 60 cadaver fingers (mean age, 77 years). Flexor digitorum profundus tendons were then transected at their insertion sites and repaired using a 4-strand grasping suture and either pull-out or anchor fixation. For pull-out repair (n = 20), the suture strands (Supramid 3-0; S. Jackson, Inc., Alexandria, VA) were passed through the distal phalanx and tied over a dorsal button. For anchor repair, 2 bone anchors were inserted into the distal phalanx, and tendons were grasped using either Supramid (n = 21), Ethibond (Ethicon, Inc., Somerville, NJ; n = 10), or FiberWire suture (Arthrex Inc., Naples, FL; n = 9) (all 3-0). Mechanical properties of the repaired tendon– bone constructs were determined in linear, load-to-failure loading and correlated with bone characteristics. Results The FiberWire-anchor repair group had the best combination of mechanical properties, with ultimate force to failure no different from the pull-out repairs but with greater stiffness and reduced displacement. Pull-out suture repairs had significantly higher ultimate force-to-failure values than did Ethibond-anchor and Supramid-anchor repairs (p anchor repairs from all groups (p anchors pulled out for bone mineral density below 420 mg/cm3 or cortical thickness less than0.31 mm, which occurred only for specimens aged greater than75 years. Conclusions The mechanical properties of the double Mitek bone anchors were sensitive to both suture material and bone quality. FiberWire-anchor repairs provided the best combination of mechanical properties. Pull-out suture repairs had good strength but poor stiffness. Anchor fixation may be contraindicated

  14. "Soft, hard, or just right?" Applications and limitations of axial-strain sonoelastography and shear-wave elastography in the assessment of tendon injuries.

    Science.gov (United States)

    Ooi, C C; Malliaras, P; Schneider, M E; Connell, D A

    2014-01-01

    Injury to a tendon leads to alterations in the mechanical properties of the tendon. Axial-strain sonoelastography and shear-wave elastography are relatively new, real-time imaging techniques that evaluate the mechanical properties of tendons in addition to the existing morphological and vascular information that is obtained with traditional imaging tools. Axial-strain sonoelastography displays the subjective distribution of strain data on an elastogram caused by tissue compression, whereas shear-wave elastography provides a more objective, quantitative measure of the intrinsic tissue elasticity using the acoustic push-pulse. Recent studies suggest that axial-strain sonoelastography is able to distinguish between asymptomatic and diseased tendons, and is potentially more sensitive than conventional ultrasound in detecting early tendinopathy. Shear-wave elastography seems to be a feasible tool for depicting elasticity and functional recovery of tendons after surgical management. While initial results have been promising, axial-strain sonoelastography and shear-wave elastography have not yet found routine use in wider clinical practice. Possible barriers to the dissemination of axial-strain sonoelastography technique include operator dependency, technical limitations such as artefacts and lack of reproducibility and quantification of sonoelastography data. Shear-wave elastography may improve the reproducibility of elastography data, although there is only one published study on the topic to date. Large-scale longitudinal studies are needed to further elucidate the clinical relevance and potential applications of axial-strain sonoelastography and shear-wave elastography in diagnosing, predicting, and monitoring the progress of tendon healing before they can be widely adopted into routine clinical practice.

  15. Wide-Awake Primary Flexor Tendon Repair, Tenolysis, and Tendon Transfer

    OpenAIRE

    Tang, Jin Bo

    2015-01-01

    Tendon surgery is unique because it should ensure tendon gliding after surgery. Tendon surgery now can be performed under local anesthesia without tourniquet, by injecting epinephrine mixed with lidocaine, to achieve vasoconstriction in the area of surgery. This method allows the tendon to move actively during surgery to test tendon function intraoperatively and to ensure the tendon is properly repaired before leaving the operating table. I applied this method to primary flexor tendon repair ...

  16. Gastrocnemius tendon length and strain are different when assessed using straight or curved tendon model

    OpenAIRE

    Stosic, Jelena; Finni Juutinen, Taija

    2011-01-01

    The present study investigated the effects of tendon curvature on measurements of tendon length using 3D-kinematic analysis. Curved and straight tendon models were employed for assessing medial gastrocnemius tendon length and strain during hopping (N = 8). Tendon curvature was identified using small reflective markers placed on the skin surface along the length of the tendon and a sum of vectors between the markers from the calcaneous up to the marker at the origin of tendon was calculated. T...

  17. Size Effect on the Mechanical Properties of CF Winding Composite

    Science.gov (United States)

    Cui, Yuqing; Yin, Zhongwei

    2017-12-01

    Mechanical properties of filament winding composites are usually tested by NOL ring samples. Few people have studied the size effect of winding composite samples on the testing result of mechanical property. In this research, winding composite thickness, diameter, and geometry of NOL ring samples were prepared to investigate the size effect on the mechanical strength of carbon fiber (CF) winding composite. The CF T700, T1000, M40, and M50 were adopted for the winding composite, while the matrix was epoxy resin. Test results show that the tensile strength and ILSS of composites decreases monotonically with an increase of thickness from 1 mm to 4 mm. The mechanical strength of composite samples increases monotonically with the increase in diameter from 100 mm to 189 mm. The mechanical strength of composite samples with two flat sides are higher than those of cyclic annular samples.

  18. The fracture properties and toughening mechanisms of bone and dentin

    Science.gov (United States)

    Koester, Kurt John

    The mechanical properties of bone and dentin and in particular their fracture properties, are the subject of intense research. The relevance of these properties is increasing as our population ages and fracture incidence impacts the lives of a greater portion of the population. A robust framework is needed to understand the fracture properties of bone and dentin to guide researchers as they attempt to characterize the effects of aging, disease, and pharmaceutical treatments on the properties of these mineralized tissues. In the present work, this framework is provided and applied to human bone, human dentin, and animal bone. In situ electron microscopy was also used to identify the salient toughening mechanisms in bone and dentin. It was found that bone and dentin are extrinsically toughened materials and consequently their fracture properties are best characterized utilizing a crack-growth resistance approach. A description of the different mechanical measurements commonly employed when using small animal models (rats and mice) to evaluate the influence of drug therapies on bone fragility is provided. A study where these properties were measured for a large population of wild-type rats and mice was also conducted. Given my findings, it was determined that for the most complete understanding of small animal bone it was necessary to measure strength and toughness. Strength measurements probe the flaw distribution and toughness measurements to evaluate the resistance to facture in the presence of a single dominant worst-case flaw.

  19. Novel methods for tendon investigations

    DEFF Research Database (Denmark)

    Kjær, Michael; Langberg, Henning; Bojsen-Møller, J.

    2008-01-01

    Purpose. Tendon structures have been studied for decades, but over the last decade, methodological development and renewed interest for metabolic, circulatory and tissue protein turnover in tendon tissue has resulted in a rising amount of investigations. Method. This paper will detail the various...

  20. Tendon Reattachment to Bone in an Ovine Tendon Defect Model of Retraction Using Allogenic and Xenogenic Demineralised Bone Matrix Incorporated with Mesenchymal Stem Cells.

    Directory of Open Access Journals (Sweden)

    Tanujan Thangarajah

    Full Text Available Tendon-bone healing following rotator cuff repairs is mainly impaired by poor tissue quality. Demineralised bone matrix promotes healing of the tendon-bone interface but its role in the treatment of tendon tears with retraction has not been investigated. We hypothesized that cortical demineralised bone matrix used with minimally manipulated mesenchymal stem cells will result in improved function and restoration of the tendon-bone interface with no difference between xenogenic and allogenic scaffolds.In an ovine model, the patellar tendon was detached from the tibial tuberosity and a complete distal tendon transverse defect measuring 1 cm was created. Suture anchors were used to reattach the tendon and xenogenic demineralised bone matrix + minimally manipulated mesenchymal stem cells (n = 5, or allogenic demineralised bone matrix + minimally manipulated mesenchymal stem cells (n = 5 were used to bridge the defect. Graft incorporation into the tendon and its effect on regeneration of the enthesis was assessed using histomorphometry. Force plate analysis was used to assess functional recovery.Compared to the xenograft, the allograft was associated with significantly higher functional weight bearing at 6 (P = 0.047, 9 (P = 0.028, and 12 weeks (P = 0.009. In the allogenic group this was accompanied by greater remodeling of the demineralised bone matrix into tendon-like tissue in the region of the defect (p = 0.015, and a more direct type of enthesis characterized by significantly more fibrocartilage (p = 0.039. No failures of tendon-bone healing were noted in either group.Demineralised bone matrix used with minimally manipulated mesenchymal stem cells promotes healing of the tendon-bone interface in an ovine model of acute tendon retraction, with superior mechanical and histological results associated with use of an allograft.

  1. Blood supply of the flexor digital tendon in the hand and its clinical significance.

    Science.gov (United States)

    Zhang, Z Z; Zhong, S Z; Sun, B; Ho, G T

    1990-01-01

    An anatomical study on the blood sources and vascularity of the flexor digital tendon was conducted in the upper extremities of fresh cadavers by means of arterial injection and meticulous dissection of the transparent tendon under the microscope. According to whether or not synovial membrane surrounded the tendon, the flexor digital tendon can be divided into 2 regions: non-synovial and synovial. The major intrinsic blood supply of the digital tendon was in the form of longitudinal vascular bundles, while the transverse anastomotic branches were short and sparse. The non-synovial region of the tendon was covered by paratenon and the vascular distribution of this region was uniform. In the synovial sheath, the blood vessels distributed only on the dorsal side, while the volar side was devoid of vessels. The profundus and superficialis tendons had an avascular zone at the proximal interphalangeal and metacarpophalangeal joints respectively. It was considered that the difference of the vascular architecture might be related to the mechanical force to which the tendon was subjected. The nutrition of tendon was discussed and the selection of tendon graft at operation was suggested.

  2. Mechanical Properties of Organic Semiconductors for Stretchable, Highly Flexible, and Mechanically Robust Electronics.

    Science.gov (United States)

    Root, Samuel E; Savagatrup, Suchol; Printz, Adam D; Rodriquez, Daniel; Lipomi, Darren J

    2017-05-10

    Mechanical deformability underpins many of the advantages of organic semiconductors. The mechanical properties of these materials are, however, diverse, and the molecular characteristics that permit charge transport can render the materials stiff and brittle. This review is a comprehensive description of the molecular and morphological parameters that govern the mechanical properties of organic semiconductors. Particular attention is paid to ways in which mechanical deformability and electronic performance can coexist. The review begins with a discussion of flexible and stretchable devices of all types, and in particular the unique characteristics of organic semiconductors. It then discusses the mechanical properties most relevant to deformable devices. In particular, it describes how low modulus, good adhesion, and absolute extensibility prior to fracture enable robust performance, along with mechanical "imperceptibility" if worn on the skin. A description of techniques of metrology precedes a discussion of the mechanical properties of three classes of organic semiconductors: π-conjugated polymers, small molecules, and composites. The discussion of each class of materials focuses on molecular structure and how this structure (and postdeposition processing) influences the solid-state packing structure and thus the mechanical properties. The review concludes with applications of organic semiconductor devices in which every component is intrinsically stretchable or highly flexible.

  3. A Novel Method of Mechanical Oxidation of CNT for Polymer Nanocomposite Application: Evaluation of Mechanical, Dynamic Mechanical, and Rheological Properties

    Directory of Open Access Journals (Sweden)

    Priyanka Pandey

    2014-01-01

    Full Text Available A new approach of oxidation of carbon nanotubes has been used to oxidize the CNTs. A comparative aspect of the mechanical oxidation and acid oxidation process has been established. FTIR analysis and titration method have shown the higher feasibility of the mechanical oxidation method to oxidize the CNTs. Comparatively less damage to the CNTs has been observed in case of mechanically oxidized as compared to acid oxidized CNTs. The mechanical properties of the nanocomposites reinforced with the acid oxidized CNT (ACNT and mechanically oxidized CNTs (McCNT were analyzed and relatively higher properties in the nanocomposites reinforced with McCNT were noticed. The less degree of entanglement in the McCNTs was noticed as compared to ACNTs. The dynamic mechanical analysis of the nanocomposites revealed much improved load transfer capability in the McCNT reinforced composites. Further, the rheological properties of the nanocomposites revealed the higher performance of McCNT reinforced composites.

  4. Method of predicting mechanical properties of decayed wood

    Science.gov (United States)

    Kelley, Stephen S.

    2003-07-15

    A method for determining the mechanical properties of decayed wood that has been exposed to wood decay microorganisms, comprising: a) illuminating a surface of decayed wood that has been exposed to wood decay microorganisms with wavelengths from visible and near infrared (VIS-NIR) spectra; b) analyzing the surface of the decayed wood using a spectrometric method, the method generating a first spectral data of wavelengths in VIS-NIR spectra region; and c) using a multivariate analysis to predict mechanical properties of decayed wood by comparing the first spectral data with a calibration model, the calibration model comprising a second spectrometric method of spectral data of wavelengths in VIS-NIR spectra obtained from a reference decay wood, the second spectral data being correlated with a known mechanical property analytical result obtained from the reference decayed wood.

  5. Microfibrous silver-coated polymeric scaffolds with tunable mechanical properties

    KAUST Repository

    Kalakonda, Parvathalu.

    2017-07-07

    Electrospun scaffolds of poly(glycerol sebacate)/poly(ε-caprolactone) (PGS/PCL) have been used for engineered tissues due to their desirable thermal and mechanical properties as well as their tunable degradability. In this paper, we fabricated micro-fibrous scaffolds from a composite of PGS/PCL using a standard electrospinning method and coated them with silver (Ag). The low temperature coating method prevented substrate melting and the Ag coating decreases the pore size and increases the diameter of fibers which resulted in enhanced thermal and mechanical properties. We further compared the mechanical properties of the composite fibrous scaffolds with different thicknesses of Ag coated scaffolds. The composite fibrous scaffold with a 275 nm Ag coating showed higher tensile modulus (E) and ultimate tensile strength (UTS) without any post-processing treatment. Lastly, potential controlled release of the Ag coating from the composite fibrous scaffolds could present interesting biomedical applications.

  6. Ultrasound-guided tendon fenestration.

    Science.gov (United States)

    Chiavaras, Mary M; Jacobson, Jon A

    2013-02-01

    A potential treatment for chronic tendinosis or tendinopathy is percutaneous ultrasound-guided tendon fenestration, also termed dry needling or tenotomy. This procedure involves gently passing a needle through the abnormal tendon multiple times to change a chronic degenerative process into an acute condition that is more likely to heal. This article reviews the literature on tendon fenestration and describes the technical aspects of this procedure including postprocedural considerations. Although peer-reviewed literature on this topic is limited, studies to date have shown that ultrasound-guided tendon fenestration can improve patient symptoms. Several other percutaneous treatments for tendinopathy that include prolotherapy, autologous whole-blood injection, and autologous platelet-rich plasma injection are often performed in conjunction with fenestration. It is currently unknown if these other percutaneous procedures have any benefit over ultrasound-guided tendon fenestration alone. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  7. Mechanical Properties for Reliability Analysis of Structures in Glassy Carbon

    CERN Document Server

    Garion, Cédric

    2014-01-01

    Despite its good physical properties, the glassy carbon material is not widely used, especially for structural applications. Nevertheless, its transparency to particles and temperature resistance are interesting properties for the applications to vacuum chambers and components in high energy physics. For example, it has been proposed for fast shutter valve in particle accelerator [1] [2]. The mechanical properties have to be carefully determined to assess the reliability of structures in such a material. In this paper, mechanical tests have been carried out to determine the elastic parameters, the strength and toughness on commercial grades. A statistical approach, based on the Weibull’s distribution, is used to characterize the material both in tension and compression. The results are compared to the literature and the difference of properties for these two loading cases is shown. Based on a Finite Element analysis, a statistical approach is applied to define the reliability of a structural component in gl...

  8. Pressing Speed, Specific Pressure and Mechanical Properties of Aluminium Cast

    Directory of Open Access Journals (Sweden)

    Gaspar S.

    2016-06-01

    Full Text Available Recent research in the process of aluminum alloy die castings production, which is nowadays deeply implemented into the rapidly growing automobile, shipping and aircraft industries, is aimed at increasing the useful qualitative properties of the die casting in order to obtain its high mechanical properties at acceptable economic cost. Problem of technological factors of high pressure die casting has been a subject of worldwide research (EU, US, Japan, etc.. The final performance properties of die castings are subjected to a large number of technological factors. The main technological factors of high pressure die casting are as follows: plunger pressing speed, specific (increase pressure, mold temperature as well as alloy temperature. The contribution discusses the impact of the plunger pressing speed and specific (increase pressure on the mechanical properties of the casting aluminum alloy.

  9. Mechanical properties and fiber type composition of chronically inactive muscles

    Science.gov (United States)

    Roy, R. R.; Zhong, H.; Monti, R. J.; Vallance, K. A.; Kim, J. A.; Edgerton, V. R.

    2000-01-01

    A role for neuromuscular activity in the maintenance of skeletal muscle properties has been well established. However, the role of activity-independent factors is more difficult to evaluate. We have used the spinal cord isolation model to study the effects of chronic inactivity on the mechanical properties of the hindlimb musculature in cats and rats. This model maintains the connectivity between the motoneurons and the muscle fibers they innervate, but the muscle unit is electrically "silent". Consequently, the measured muscle properties are activity-independent and thus the advantage of using this model is that it provides a baseline level (zero activity) from which regulatory factors that affect muscle cell homeostasis can be defined. In the present paper, we will present a brief review of our findings using the spinal cord isolation model related to muscle mechanical and fiber type properties.

  10. Phase imaging of mechanical properties of live cells (Conference Presentation)

    Science.gov (United States)

    Wax, Adam

    2017-02-01

    The mechanisms by which cells respond to mechanical stimuli are essential for cell function yet not well understood. Many rheological tools have been developed to characterize cellular viscoelastic properties but these typically require direct mechanical contact, limiting their throughput. We have developed a new approach for characterizing the organization of subcellular structures using a label free, noncontact, single-shot phase imaging method that correlates to measured cellular mechanical stiffness. The new analysis approach measures refractive index variance and relates it to disorder strength. These measurements are compared to cellular stiffness, measured using the same imaging tool to visualize nanoscale responses to flow shear stimulus. The utility of the technique is shown by comparing shear stiffness and phase disorder strength across five cellular populations with varying mechanical properties. An inverse relationship between disorder strength and shear stiffness is shown, sugg