Primary biomechanical influence of different sterilization methods on a freeze-dried bone-ligament transplant

Abstract

The transmission of bacteria and viruses in ligament transplants should be prevented by sterilization. In this study, the influence of two different methods on the mechanical properties of a freeze-dried medial collateral ligament was analyzed in sheep. Group I (n = 10) was treated with irradiation (26 kGy) and group II (n = 10) with ethyleneoxide. The mechanical properties changed in respect of the maximal load: group I (–29.9%; P < 0.05), group II (–7.7%), elongation: group I (–6.6%), group II (–0.3%), stress: group I (–20.1%), group II (–6.8%), strain: group I (–0.64%), group II (–0.3%), stiffness: group I (–10.2%), group II (–10.5%), energy: group I (–31.4%), group II (–6.9%) and elastic modulus: group I (–1.3%), group II (–5.0%). The irradiation dose significantly reduced the maximal load, whereas ethyleneoxide sterilization resulted only in minor changes. Because of the potential cancerogenity of ethyleneoxide, a close monitoring of aeration times and its residuals are very essential. Further studies with lower irradiation doses of between 15 and 26 kGy seem to be justified.