Changes in the mechanical properties of tibialis anterior and peroneus longus allograft depending on sterilization method and storage time.

Abstract

Aims: The aim of the present research was to analyze the effects of different sterilization methods and storage times on the mechanical properties (load at first break, strain at first break, maximum load, strain at maximum load, and Young's modulus of elasticity) of different allografts compared to native groups.

Methods: Two types of grafts were harvested from human cadavers: 165 tibialis anterior (TA) and 166 peroneus longus (PL) tendons. According to the two types of sterilization methods (γ and electron beam irradiation) or the lack of one, and the six types of storage time (one to six months), 36 groups were created. In addition, we created a 1 to 1 native group, which was not sterilized and stored, tested within four hours of collection.

Results: In the results of tendon type TA compared to TA native group, we observed significant differences at the fifth month of storage for all measured parameters. Load at first break of the frozen values at the fifth month was significantly inferior to the native group (p = 0.034). For strain at first break and strain at maximum load, all sterilization methods were significantly inferior at the fifth month (p = 0.003 to p = 0.009). Maximum load values were significantly superior with E-beam irradiation at the fifth month (p = 0.003), and also significantly higher with γ irradiation at the fifth month (p = 0.009). Young's modulus showed significantly inferior values in the frozen tendons at the fifth month (p = 0.001 to p = 0.003). In tendon type PL, no significant differences were found for any of the tested parameters compared to the native group.

Conclusion: Our results indicate that freezing alters mechanical properties via the decrease seen in the ultimate tensile strength. In addition, at the fifth and sixth months of storage, time could notably affect allografts rather than the sterilization procedures.