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. 2018 Jan 10;7(3):548-553.
doi: 10.11138/mltj/2017.7.3.548. eCollection 2017 Jul-Sep.

The effect of strain and age on the mechanical properties of rat Achilles tendons

Emily C Vafek  1 , Johannes F Plate  1 , Eric Friedman  1 , Sandeep Mannava  1 , Aaron T Scott  1 , Kerry A Danelson  1
Affiliations

The effect of strain and age on the mechanical properties of rat Achilles tendons

Emily C Vafek et al. Muscles Ligaments Tendons J. .

Abstract

Background: Achilles tendon (AT) ruptures are common in the middle age population; however, the pathophysiology and influence of age on AT ruptures is not fully understood. This study evaluates the effect and interactions between, strain and age on the in vitro biomechanical properties of ATs.

Methods: Bilateral ATs were harvested from 17 young (8 months) and 14 middle-aged (24 months) rats and underwent stress-relaxation using Fung's quasilinear viscoelastic (QLV) modeling and load-to-failure testing.

Results: The initial viscoelastic response (parameter B) in middle-age animals was dependent on the amount of strain applied to the tendon and was significantly increased in middle-aged animals at higher strain. Higher strain in older animals led to a prolonged relaxation time (parameter tau 2). There was a trend toward an increased magnitude of the relaxation response (parameter C) at higher strain in the middle-aged animals. Middle-aged animals had a significantly lower mean stress at ultimate failure (p=0.01), while Young's modulus was similar in both groups (p=0.46).

Conclusions: The passive biomechanical properties of the rat AT change with age and the influence stress-relaxation response of the AT, thereby possibly predisposing the AT of older animals to fail at lower loads compared to younger animals.

Level of evidence: Not applicable, this is a basic science study.

Keywords: Achilles tendon rupture; aging; fung; quasilinear viscoelastic.

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Conflict of interest statement

Conflict of interest No other relationships, conditions, or circumstances present potential conflict of interest.

Figures

Figure 1
Figure 1
Box plots of the comparison of Young’s modulus and ultimate failure stress demonstrating the similarity in the modulus and the variation in failure stress.
See this image and copyright information in PMC

References

    1. Leppilahti J, Puranen J, Orava S. Incidence of Achilles tendon rupture. Acta Orthop Scand. 1996;67(3):277–279. - PubMed
    1. Suchak AA, et al. The incidence of Achilles tendon ruptures in Edmonton, Canada. Foot Ankle Int. 2005;26(11):932–936. - PubMed
    1. Jarvinen TA, et al. Achilles tendon injuries. Curr Opin Rheumatol. 2001;13(2):150–155. - PubMed
    1. Sharma P, Maffulli N. Tendon injury and tendinopathy: healing and repair. J Bone Joint Surg Am. 2005;87(1):187–202. - PubMed
    1. Lin R, Chang G, Chang L. Biomechanical properties of muscle-tendon unit under high-speed passive stretch. Clin Biomech (Bristol, Avon) 1999;14(6):412–417. - PubMed

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