Mandibular reconstruction with a prefabricated vascularized bone graft using recombinant human osteogenic protein-1: an experimental study in miniature pigs. Part 1: Prefabrication

Osteogenic protein-1 (rhOP-1), also called bone morphogenetic protein-7 (BM P-7), is osteoinductive. It may be possible to reconstruct a mandible by lo cal application of rhOP-1. However, in tumour patients this can be impossib le due to scars or preceding radiotherapy. Usually vascularized bone grafts are indicated. The aim of this study was to prefabricate a vascularized bo ne graft in the latissimus dorsi muscle for microsurgical transplantation. In nine minipigs 600 mug rhOP-1 were used with 8 ml xenogenic bone mineral (BioOss (R), Geistlich, Waldenburg, Germany) as a carrier and inserted into a pouch prepared in the M. latissimus dorsi, After 6, 12, and 24 weeks the grafts were harvested. The results were evaluated using computed tomograph y, histology, macro- and microangiography. A high yield of newly formed bon e was obtained on the osteoconductive scaffold of the xenogenic bone. It wa s possible to create a vascularized osseous graft in the given shape of the BioOss blocks. In cross-sections, 68% of the scaffold was coated with new bone. The amount of new bone did not differ between the prefabrication time s. Bone overgrowth was 2.1% of the graft volume. In conclusion, this study has shown that it can be possible to prefabricate a neomandible within a mu scle graft. which then could be transferred for microvascular reconstructio n of the mandible. Further research is required before this technique can b e refined for clinical use.