Bone formation in cranial, mandibular, tibial and iliac bone grafts in rats

Several studies have suggested that grafts from membranous derived bone (e.g., calvarial grafts) retain their volume better than those from endochondral derived bone (e.g., iliac bone grafts). Increased osteogenesis in grafts of the former type has been offered as the explanation. However, simple volume measurements of the recovered grafts do not differentiate between viable and dead bone. We studied fresh syngeneic full-thickness bone grafts from calvaria, mandibula, tibia diaphysis, and iliac bone implanted in the back muscles of young Lewis rats. Bone formation in grafts recovered 3 weeks postoperatively was quantitatively evaluated by strontium 85 uptake analyses. We found that the strontium 85 uptake was greater in calvarial and mandibular grafts than in tibial grafts. No difference was found among calvarial, mandibular, and iliac grafts or between tibial and iliac grafts. We conclude that the anatomical area of harvest is important regarding new bone formation in syngeneic bone grafts. However, the results do not support the contention that better maintenance of volume of calvarial grafts compared with iliac bone grafts is due to enhanced osteogenesis in the former.