REVASCULARIZATION OF CALVARIAL, MANDIBULAR, TIBIAL, AND ILIAC BONE-GRAFTS IN RATS

Some studies have suggested that membranous bone grafts undergo less r esorption than endochondral grafts, and faster revascularization of th e former has been proposed as the explanation. We studied fresh syngen eic full-thickness bone grafts from calvaria, mandibula, tibia diaphys is, and iliac bone implanted in the back muscles of young Lewis rats. As a measure of the quantity of cancellous bone in grafts before impla ntation, the ratio of the total area of soft-tissue spaces to the tota l area of the graft was measured histomorphometrically. Revascularizat ion in grafts 3 weeks postoperatively was evaluated by deposit of Ce-1 41-labeled microspheres. Both the quantity of cancellous bone (before implantation) and the revascularization (3 weeks postoperatively) were greater in the mandibular and iliac bone grafts than in the calvarial and tibia diaphyseal grafts. The results suggest that the anatomical area of harvest of bone graft is important regarding early revasculari zation, but the results do not support the theory that different embry ological mode of development is the cause since mandibula (high Ce-141 index) and calvaria (low Ce-141 index) are of membranous origin and i liac bone (high Ce-141 index) and tibia (low Ce-141 index) are of endo chondral origin. The difference in revascularization between the diffe rent grafts may be explained by differences in quantity of cancellous bone since cancellous bone is revascularized faster than cortical bone .