The effect of prolonged ischemia time on osteocyte and osteoblast survival in composite bone grafts revascularized by microvascular anastomoses

Twenty-six adult mongrel dogs were used to investigate the effect of prolonged ischemia on osteocyte and osteoblast survival in composite bone grafts revascularized by microvascular anastomoses. The bone grafts were stored in chilled (+5 degrees C) Collins-Terasaki solution, and ischemia time varied from 90 minutes to 48 hours. With histologic techniques and fluorochrome bone labeling it was shown that the bone marrow, the osteocytes, and the osteoblasts could completely survive up to 25 hours of ischemia. Although bone grafting techniques are employed routinely in many orthopedic and plastic surgical procedures, our knowledge is incomplete concerning the ischemic period tolerated by osteocytes and osteoblasts in these grafts. This information is essential when bone transfer on microvascular pedicles is employed, since 3 to 6 hours of ischemia time may be necessary in these operations. The present experiment has shown that osteocytes and osteoblasts can survive a rather long ischemic period if the medullary nutrient blood supply is later reconstituted. This fact adds validity to the technique of free vascularized bone grafts in reconstructive surgery.