Revascularization of cranial versus iliac crest bone grafts in the rat

Full-thickness cranial (membranous) and split-thickness iliac crest (endochondral) onlay bone grafts were placed subperiosteally without fixation onto the snout (membranous) and tibia (endochondral) in 30 rats. The animals had been divided into three equal groups in which the bone grafts had been demineralized, autoclaved, or used fresh. Recipient sites were harvested at 7 and 14 days at the snout and 14 days at the tibia, and revascularization was studied utilizing silicone rubber injection and a gridcounting technique. Endochondral grafts were found to have quantitatively greater revascularization than membranous grafts in all three groups at both sites (p less than 0.005). There was generally no statistically significant difference in revascularization between fresh and demineralized grafts, but vessel ingrowth was significantly decreased in autoclaved implants as compared with fresh grafts. Differences in graft architecture are theorized to account for the disparity in revascularization in endochondral and membranous grafts. Angiogenic and chemotactic factors are thought to play a role in the similarities and differences in revascularization among fresh, demineralized, and autoclaved bone.