Tensile properties of human Achilles tendon

There were three foci of this study. The first was a delineation of the effect of two variables on the tensile properties of human Achilles tendon, To that end, the values of the ultimate tensile strength, UTS, strain at the UTS point, ε_max and tangent modulus of elasticity, E_T, of cadaveric Achilles tendon were obtained as a function of (a) donor age (36 to 100 y), at a fired loading rate of 10 %/s; and (b) loading rate (for tendons from the 52to 67-year-old donor group). The second focus was the presentation of a suitable constitutive relation between the tensile stress, σ, and the tensile strain, ε, for this tissue. The aim of these two foci was to provide information that will aid in the selection of Achilles tendon for the repair of ruptured Achilles tendons as well as anterior cruciate ligaments (ACLs). The third focus was, thus, a comparison of the tensile properties of Achilles tendon and patellar tendon, which is now widely used for the repair of ruptured ACLs. It was found that: (a) age exerts a marked effect on UTS, an insignificant one on ε^max and a moderate one on E_T; (b) a ten-fold increase in loading rate results In a moderate but insignificant increase in UTS, a significant decrease in ε_max , and a significant increase in E_T; (c) a suitable constitutive relation is σ=Cεexp[Dε+Fε² ], with C, D, and F being material constants; and (d) the tensile properties of Achilles and patellar tendons have similar values