Mandibular reconstruction with prefabricated vascularized bone grafts using recombinant human osteogenic protein-1: an experimental study in miniature pigs. Part II: transplantation.

Osteogenic Protein-1 (rhOP-1), also called bone morphogenetic protein-7 (BMP-7), is osteoinductive. The aim of this study was to present a new surgical technique: the prefabrication of a vascularized bone graft using rhOP-1 and its microsurgical transplantation. During 6 weeks, osteomuscular grafts were prefabricated in the latissimus dorsi muscle of five adult minipigs. Six hundred micrograms rhOP-1 on a carrier of xenogenic bone mineral in block form were used. The grafts were transplanted into defects of the mandibular angles performing a microsurgical anastomosis and using miniplates for fixation. Identical defects of the contralateral side were treated by direct application of 600 microg rhOP-1 and xenogenic bone mineral. A polychrome sequential labelling was applied. After transplantation the bone stayed viable, demonstrated by continuous apposition of fluorochromes (non-decalcified histologic sections) and bone scintigraphy. The reconstructive result was significantly superior in the prefabrication technique, assessed by histology and computerized tomography (CT). In conclusion, the method has a potential to become a clinical alternative for conventional vascularized bone grafts.