Effects of Creep and Cyclic Loading on the Mechanical Properties and Failure of Human Achilles Tendons

Wren, Tishya A. L.; Lindsey, Derek P.; Beaupré, Gary S.; Carter, Dennis R.

doi:10.1114/1.1569267

Cited by 211 publications

(238 citation statements)

References 22 publications

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“…Exercise may have induced an increased capacity of tenocytes to repair microdamage, but no analysis was performed on the metabolic activity of the cells within the tendon in this study. In addition, fatigue resistance is a difficult characteristic to measure objectively with biological relevance, although some attempts have been made in other species (31,47,63).…”

Section: Discussionmentioning

confidence: 99%

Can exercise modulate the maturation of functionally different immature tendons in the horse?

Kasashima

Takahashi²,

Birch³

et al. 2008

Journal of Applied Physiology

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Tendons can be considered in two functional groups, those contributing to energetics of locomotion and those acting solely to position the limb. The energy-storing tendons in both human and equine athletes have a high frequency of injury with similar pathophysiology. In previous studies, high-intensity exercise appears to induce a disruption of the matrix rather than functional adaptation in adults. Here we explore the hypothesis that the introduction of controlled exercise during growth would result in an adaptive response without deleterious effects. Young horses were given a controlled exercise program similar to that previously shown to induce matrix changes in energy-storing tendons of skeletally mature animals. The tendons were assessed in relation to mechanical properties, molecular composition, and morphology. Results showed a significant increase in cartilage oligomeric matrix protein (COMP) in the positional tendon but not in the energy-storing tendon. Other matrix properties and mechanical properties were not significantly changed. While the imposition of high-strain-rate exercise in immature horses failed to augment the development of the energy-storing tendon over and above that induced by normal pasture exercise, it did not induce deleterious changes, supporting an earlier introduction of athletic training in horses.adaptation; hypertrophy; cartilage oligomeric matrix protein; biomechanics TENDON OVERUSE INJURIES are not only responsible for considerable loss of athletic potential in both horses (30,35,58) and humans (64), but their prevalence appears to be increasing, with a doubling in Achilles tendinopathy in recent years (26,27,34,37,38). While tendons that link muscle to bone can act merely as force transmitters to position limbs, a specific subgroup of tendons whose function is to store elastic energy contributes to efficient locomotion by acting as springs, while the associated muscle fibers serve primarily to dampen vibrations (1, 59). The Thoroughbred racehorse is a prime example of an elite animal athlete both in terms of evolution and subsequent genetic selection and conditioning. The superficial digital flexor tendon (SDFT) in the horse is an energy-storing tendon with functional and compositional similarities to the Achilles tendon in humans (7). This tendon is highly susceptible to injury, accounting for 93% of all tendon and ligament injuries in a study by Ely et al. (15) and thus can be used as a "natural" model to study tendon development and degeneration (51). The common digital extensor tendon (CDET) in contrast is a good example of a positional tendon analogous to the anterior tibialis in the human (3, 62).Over the last two decades there has been a great increase in the scientific understanding of the response of bone and muscle to mechanical loading. The mechanobiology of tendon, however, is less well understood. Effects of exercise on tendon properties have been studied in various species, including mouse (36), rat (49, 55), rabbit (61), chicken (2), guinea fowl (8), miniatur...

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Section: Discussionmentioning

confidence: 99%

Can exercise modulate the maturation of functionally different immature tendons in the horse?

Kasashima

Takahashi²,

Birch³

et al. 2008

Journal of Applied Physiology

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“…While there is an active debate regarding the relative continuity/interconnectivity of collagen fibrils and how collagen fibrils are effectively cross-linked and/or interwoven to provide structural integrity (Provenzano and Vanderby, 2006), a large number of studies suggest that collagen fibrils are relatively short and assume a discontinuous fibril network (Birk et al, 1997;Dahners et al, 2000;Mosler et al, 1985;Thurmond and Trotter, 1994;Trotter and Koob, 1989). Thus tendon is widely modeled as a fiber reinforced composite material in which force is laterally transferred between neighboring fibrils (Ciarletta et al, 2008;Haut, 1986;Humphrey and Yin, 1987;Korhonen et al, 2003;Lanir, 1978;Mommersteeg et al, 1996;Preston and Meyer, 1971;Wren et al, 2003). However, the mechanism that governs lateral load transfer among collagen fibrils is largely unknown.…”

Section: Introductionmentioning

confidence: 99%

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

Fessel¹,

Snedeker²

2009

Matrix Biology

138

112

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Evidence against proteoglycan mediated collagen fibril load transmission and dynamic viscoelasticity in tendon Fessel, G; Snedeker, J G Fessel, G; Snedeker, J G (2009 The glycosaminoglycan (GAG) dermatan sulphate and chondroitin sulphate side-chains of small leucine-rich proteoglycans have been increasingly posited to act as molecular cross links between adjacent collagen fibrils and to directly contribute to tendon elasticity. GAGs have also been implicated in tendon viscoelasticity, supposedly affecting frictional loss during elongation or fluid flow through the extra cellular matrix.The current study sought to systematically test these theories of tendon structure-function by investigating the mechanical repercussions of enzymatic depletion of GAG complexes by chondroitinase ABC in a reproducible tendon structure-function model (rat tail fascicles). The extent of GAG removal (at least 93%) was verified by relevant spectrophotometric assays and transmission electron microscopy. Dynamic viscoelastic tensile tests on GAG depleted rat tail tendon fascicle were not mechanically different from controls in storage modulus (elastic behavior) over a wide range of strain-rates (0.05, 0.5, and 5% change in length per second) in either the linear or nonlinear regions of the material curve. Loss modulus (viscoelastic behavior) was only affected in the nonlinear region at the highest strain rate, and even this effect was marginal (19% increased loss modulus, p=0.035). Thus glycosaminoglycan chains of small leucine rich proteoglycans do not appear to mediate dynamic elastic behavior nor do they appear to regulate the dynamic viscoelastic properties in rat tail tendon fascicles.

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“…The material testing system is the most direct and valid method for assessing in-vitro tendon elastic properties [20,21]. However, this method cannot be applied in-vivo.…”

Section: Discussionmentioning

confidence: 99%

A Novel Method for Assessing Regional Tendon Stiffness and Its Significance

Wang

Huang

2018

Applied Sciences

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Elastography can be used to estimate the regional shear modulus of a tendon. This can advance our knowledge on the impact of patellar alignment and regional patellar tendon stiffness. This is important as patellar tendon abnormality is mainly found in the medial portion of the tendon in subjects with proximal patellar tendinopathy. This paper aims to assess the effect of patellar displacement on differential modulation on the shear modulus of the patellar tendon. Shear modulus is captured on the medial and lateral half of the patella tendon using the Axiplorer ® ultrasound unit in conjunction with a 4-15 MHz, 50 mm linear transducer with the patellar being positioned in its resting, medio-and laterally displaced positions on 40 adults (19 females, 21 males). When the patellar is displaced laterally, the shear modulus is significantly increased at the medial half in both genders but decreased at the lateral half only in females. Conclusions: Elastography detects changes in regional tendon stiffness associated with alteration in patellar positions. The modulation on the shear modulus is gender and region specific.

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Effects of Creep and Cyclic Loading on the Mechanical Properties and Failure of Human Achilles Tendons

Cited by 211 publications

References 22 publications

Can exercise modulate the maturation of functionally different immature tendons in the horse?

Can exercise modulate the maturation of functionally different immature tendons in the horse?

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

A Novel Method for Assessing Regional Tendon Stiffness and Its Significance

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