Does Irradiation Adversely Impact Bone Forming Properties of Demineralized Bone Matrix and Allograft Bone? A Systematic Review of the Literature

Introduction: Demineralized bone matrix (DBM) and allograft bone grafts are used to increase bone formation and stabilize large defects or fusion sites. Donor factors and processing methods can alter bone grafts. The effects of sterilization by irradiation on physical properties of bone grafts are under described. We systematically reviewed the literature to (i) investigate the effects of irradiation on the biophysical properties of DBM and allograft bone and (ii) determine if irradiation impacts in vivo bone formation and clinical outcomes.

Methods: A systematic review was performed following PRIMSA guidelines using PubMed, EMBASE, and Cochrane databases. Inclusion criteria included: laboratory studies (ex vivo) and animal studies (in vivo) reporting the outcomes of irradiation on mechanical and biological properties of different allograft bone types and DBM products including comparative human studies reporting the effect of irradiation on clinical outcomes.

Results: Of the included studies, 51 were laboratory, 22 were animal, 4 were laboratory and animal, and 5 were clinical. The effects of irradiation on mechanical properties of allograft bone were inconsistent. Eighty three percent of studies reporting elastic modulus showed no significant change with irradiation. All studies evaluating fatigue life reported a significant reduction in irradiated bone allograft. Seventy-five percent of studies reporting osteoinductivity showed a significantly negative effect or dose-dependent effect of irradiation using in vivo ectopic rat models. Effects included reduced bone formation, mineralization, alkaline phosphatase activity, or osteocalcin expression. Sixty percent of clinical studies compared irradiated with non-irradiated bone allograft and reported inconsistent effects of irradiation on outcomes.

Conclusion : Irradiation may impact mechanical and biological properties of allograft bone grafts. Variable experimental design hinders identifying specific sources, doses, or protocols with detrimental effects. High quality clinical data is necessary to determine the effects of irradiated allograft bone on graft incorporation and clinical outcomes.