[Effect of gamma irradiation sterilization on the osteoinductive capacity of demineralized bone matrix]

ABSTRACT

Gamma irradiation has been widely used for secondary sterilization of bone allograft before clinical use to reduce the risk of infection and associated complications. The current study evaluated the effect of gamma irradiation sterilization on the osteoinductive capability of human demineralized bone matrix using a rat model. Eighteen euthymic rats received two separate implants consisting of 30 mg sterile-harvest demineralized bone matrix and 30 mg gamma irradiation-sterilized demineralized bone matrix. The demineralized bone matrix from each group was placed into two separate muscle pouches created in the paravertebral muscles of each rat. All 18 rats were euthanized after 4 weeks and each implantation site was removed with 0, 5 cm normal tissue around the implant. Histological examination was performed to determine the presence or absence of new bone, cartilage and bone marrow elements, All except one of 18 [94.4%] sterile-harvest demineralized bone matrix sites histologically contained new bone elements and five of 18 [27.7%] ethylene oxide sterilized demineralized bone matrix sites showed evidence of new bone elements, which was statistically significant [p<0.05]. The results of this study indicate that demineralized bone matrix sterilized with gamma irradiation loses its osteoinductive capacity in a manner similar to that of steamsterilized demineralized bone matrix, making it unsuitable as a method of secondary sterilization of demineralized bone matrix