Does a different dose of gamma irradiation have the same effect on five different types of tendon allografts? - a biomechanical study.

INTRODUCTION: The goals of our study were to evaluate the biomechanical differences between five tendons and the changes in biomechanical properties caused by irradiation.

METHODS: Achilles, quadriceps, semitendinosus + gracilis (STG), tibialis anterior (TA) and the peroneus longus (PL) were harvested from 30 donors. Group A contained 50 tendons without gamma irradiation. The groups were irradiated with a dose of 21 kGy (group B 50 tendons) and with a dose of 42 kGy (group C 50 tendons). The grafts were soaked in a radio-protectant solution and frozen at -80 °C. Cyclic loading tests were performed followed by load to failure tests. Young modulus of elasticity, maximum force, strain at tensile strength and strain at rupture were calculated.

RESULTS: The Achilles tendons had significantly lower Young modulus than the TA (p = 0.0036) in group A. The Achilles showed significantly lower than PL (p = 0.000042) and TA (p = 0.00142) in group B and C. The quadriceps and the ST (p = 0.0037) provided poorer values than the TA (p = 0.0432) in group C. We found no difference in maximum loads among the tendons in group A. The maximum load of the Achilles and quadriceps showed better results than the PL (p = 0.0016), (p = 0.0018) and the STG (p = 0.0066), (p = 0.0019) in group C. The TA had similar results like the Achilles and quadriceps.

DISCUSSION AND CONCLUSIONS: The vulnerability of gamma irradiation of TA was less than Achilles and quadriceps tendons.