The use of irradiation to sterilise bone allografts

Large skeletal defects are often encountered in the surgery of bone tumours, revision arthroplasty and trauma. Skeletal stability can be restored using either large endoprostheses or structural allografts. The latter have the advantage of restoring bone in the defect. However, transplantation of allograft bone carries with it the risk of transmissal of contaminant or blood borne infection. Sterilisation of such grafts is commonly performed by the use of gamma irradiation.;The first part of this study was the audit of an allograft bank to determine the incidence of contamination of the grafts and the risk of subsequent infection. Five percent of femoral head grafts and eighteen percent of bulk grafts yielded positive bacterial cultures. The cultures indicate that the organisms which contaminate an individual graft are not the same organisms that cause subsequent clinical sepsis of that graft.;Blood borne disease may be eliminated by irradiation of bone graft at sufficient dosage. However large doses of irradiation may weaken the biomechanical properties of the graft or interfere with its incorporation. The second part of this study was the development of a simple animal model of allograft incorporation.;The final part of the study used this model to explore the question whether irradiation of bone grafts, at a commonly used dosage, interferes with graft incorporation. The results confirm that there is a marked difference between the incorporation of autograft and allograft. However, no statistically significant difference was observed between the incorporation of irradiated and non-irradiated allografts. The strong periosteal response of the host bone probably masks any possible effect of irradiation on incorporation in this model. Suggestions for future research are given.