The effect of sterilization and storage on the viscoelastic properties of human tendon allografts - Continued: Storage for 0 to 4 months.

The role of donor-derived tendons, also known as allografts, in anterior cruciate ligament replacement surgeries is steadily increasing. Before surgery, temporary storage and, in most cases, sterilization are essential. It is, thus, crucial to determine how these procedures alter the grafts' biomechanical properties. The purpose of this research was to analyze the effect of different sterilization methods (native, frozen, frozen + 21 kGy gamma irradiation, frozen + 21 kGy electron beam irradiation) and storage durations (0 to 4 months) on the deformation and creep of two tendon types (tibialis anterior, peroneus longus). 80 tibialis anterior and 83 peroneus longus tendons from 51 human cadavers were included. The samples were removed, placed in a radio-cryoprotectant solution, then slowly cooled, sterilized and stored at -80 °C. All groups were subject to 60 s static creep test with 250 N load. Deformation during the loading phase, creep during static loading, and the ratio of these two were evaluated. Deformation at the end of the loading phase and creep consistently exhibited significantly smaller values in the tibialis anterior compared to the peroneus longus type, as well as in electron beam-sterilized grafts as opposed to gamma beam-sterilized ones. Prolonged storage periods (within 0 to 4 months) resulted in a notable increase in these values, particularly in deformation. Based on the experimental data, the tibialis anterior tendon type and sterilization by gamma beam irradiation are better choices for anterior cruciate ligament reconstruction than the peroneus longus and sterilization by electron beam. Increased storage time affects negatively the evaluated mechanical properties.