Free vascularized bone grafts: factors affecting their survival and ability to heal to recipient bone defects.

Composite bone grafts revascularized by microvascular anastomoses with respect to bone cell survival, vessel architecture, and the grafts' ability to participate in healing toward a recipient bone were investigated in 21 adult mongrel dogs. Bone grafts with an intact medullary and periosteal supply were compared with bone grafts with only periosteal bone supply intact. It was demonstrated that bone grafts with both medullary and periosteal blood supplies survived completely but were partially resorbed with time. Periosteally supplied bone grafts demonstrated less resorption but showed, in some grafts, bone marrow necrosis and partial loss of osteocytes. The osteoblasts survived equally well in both groups. No difference in the ability to participate in healing to a recipient bone defect could be demonstrated, although microangiograms revealed significant differences in the medullary microvasculature and at the host-graft junctions in these two types of grafts. The question of whether to preserve the medullary blood supply when transferring whole bone segments by microvascular anastomoses is significant with respect to possible donor-site selection. This study has shown that bone grafts with an intact medullary and/or periosteal blood supply will survive transplantation and participate in healing to a recipient defect equally well.