Neovascularized bone grafts: experimental investigation

Vascularized bone grafts are standardized procedures in reconstructive surgery but there are some disadvantages: donor site morbidity, limited number of "natural" donor sites, and complex technique. In this study, we test the possibility of creating a "neovascularized" bone graft utilizing a vascular implantation procedure in a rabbit model. Sixteen New Zealand adult white rabbits were used. In each animal, two iliac crest bone grafts (7 x 7 x 10 mm) were harvested. Vascular implantation of the right superficial femoral vessels was performed in one of the two grafts, which was wrapped in a silicone envelope to avoid neovascularization from the surrounding tissues and positioned in a subcutaneous pocket in the right medial thigh. On the left side, the bone block, wrapped in the silicone envelope, was buried subcutaneously without vascular implantation. The operated animals were divided into two groups: Group I included eight rabbits explanted 4 weeks postoperatively and Group II included eight rabbits explanted 8 weeks postoperatively. Tetracycline injection was performed 72 hours preexplantation to evaluate new bone formation. Selective colloidal ink injection in the axial artery was performed to investigate the neovascularization before inclusion in poly-methyl-methacrylate (PMMA). Histological examination was performed in all explanted specimens comparatively. Histological examination 8 weeks after surgery showed a marked neovascularization, with normal bone cells. Tetracycline labeling showed new bone formation with a normal pattern. In all nonvascularized specimens, no viable cells or neovascularization and no bone formation were found. The vascular implantation procedure can induce a good neovascularization with new bone formation in a small bone graft. The possibility of neovascularization induction by the simple vascular implantation procedure has several clinical implications in reconstructive surgery.