Effects of presurgical and post-surgical irradiation on the healing process of Medpor (R) in dogs

The purpose of this study was to determine the effect of irradiation on the healing process and the effect on the contact surface of Medpor(R) and bon e. Eighteen dogs were studied. The animals were divided into three groups. Six non-irradiated dogs served as controls (Group 1). Twelve dogs irradiate d on the left femur. before and after implantation of Medpor(R), were studi ed. The dogs were euthanized 4 and 8 weeks after Medpor(R) was implanted in presurgical irradiation subgroup animals (Group 2) and after the completio n of irradiation in post-surgical irradiation subgroup animals (Group 3). L ight microscopic and scanning electron microscopic examinations were perfor med. The appearance of osteoblasts and bone matrix formation were remarkabl y late and manifest slight reactions in post-surgical irradiation group com pared to the control group presenting the osteoblasts at 4 weeks, and those osteoblasts were not visible in presurgical irradiation group in both the 4-week and 8-week observation. We concluded that the bone remodeling was de layed in the irradiated bone, especially in the presurgical group.