Membranous vs Endochondral Bone Autografts

Twenty-four rabbits were used to compare the fate of membranous bone from the frontoparietal region with endochondral bone taken from the ilium. Both types of bone were placed subcutaneously and subperiosteally. Animals were killed in groups of six, at 1, 3, 6, and 12 months. Membranous bone grafts showed an increase in volume at each time period regardless of recipient site. Endochondral bone showed evidence of resorption, with only 25% of its original volume remaining at one year, regardless of recipient site. Both types of bone were similar histologically at one year in that they were almost totally replaced by new bone. They differed in that membranous bone maintained its architecture and endochondral bone was transformed into a thin shell of lamellar bone.