The prefabrication of a bone graft in a rat model

The prefabrication of bone grafts in a rat model was investigated. In 26 Sprague-Dawley rats, free iliac crest bone graft was harvested, bivalved, and reinserted heterotopically into the groin, where it was closed around the mobilized superficial inferior epigastric vascular bundle. In half the animals, the vascular bundle remained in continuity as a flow-through pedicle (group 1); in the remaining animals, the pedicle was ligated and divided distal to the bone graft. All grafts were isolated from other tissues by a silicone sheet envelope. At 3 or 6 weeks, the grafts were re-explored and analyzed by India ink perfusion and histologic examination for evidence of viability and neovascularization. Three weeks after insertion, India ink perfusion of the group 1 and 2 grafts revealed neovascularization extending to the periphery of the graft, and histologic examination showed extensive new bone formation on endosteal, periosteal, and trabecular surfaces of the graft. Six weeks after insertion, creeping substitution had almost completely remodelled the cortical and cancellous bone of both group 1 and 2 grafts to create a viable vascularized bone graft on a pedicle. In 3 control nonvascularized grafts (free iliac cortical bone without an implanted pedicle), all pre-existing bone of the graft was dead 3 weeks after insertion, and only very limited new bone formation was present within the graft.