Radiation sterilized bone response to dynamic loading

Allogeneic bone grafts are used on a large scale in surgeries. To avoid the risk of infectious diseases, allografts should be radiation-sterilized. So far, no international consensus has been achieved regarding the optimal radiation dose. Many authors suggest that bone sterilization deteriorates bone mechanical properties. However, no data on the influence of ionizing radiation on bone dynamic mechanical properties are available. Bovine femurs from 2-year old animal were machine cut and irradiated with the doses 10, 15, 25, 35, 45 and 50 kGy. Dynamic mechanical analysis was performed at 1–10 Hz at the temperature range of 0–350 °C in 3-point bending configuration. No statistically significant differences in storage modulus were observed. However, there were significant decreased values of loss modulus between the samples irradiated with doses of 10 (↓14.3%), 15, 45 and 50 kGy (↓33.2%) and controls. It was stated that increased irradiation dose decreases the temperature where collagen denaturation process starts and increases the temperature where the collagen denaturation process finishes. It was shown that activation energy of denaturation process is significantly higher for the samples irradiated with the dose of 50 kGy (615 kJ/mol) in comparison with control samples and irradiation with other doses (100–135 kJ/mol).