In vivo studies of bone grafts. The possibility of vascular anastomoses in healing bone.

A titanium chamber enabling vital microscopic studies of bone tissue in situ was installed in the tibiae of 10 rabbits. Using a gentle surgical technique the chamber and surrounding bone were cut in bloc, twisted 360 degrees and reinserted into the same donor bed. Vital microscopy of these orthotopical bone grafts revealed that the circulation was mainly regained via ingrowth of newly developed vessels of host origin, starting at 5--8 days after grafting. Bone remodelling was observed at 3 weeks post grafting in these cases. In two grafts, however, an additional mode of blood flow recovery was seen. Here vessels of more than 30 microns width, registered before grafting, apparently were functioning also afterwards, indicating end-to-end anastomoses between host and pre-existing graft vessels. In these two grafts bone remodelling started as early as 1 week after transplantation.