Platelet-rich plasma, rhOP-1 (rhBMP-7) and frozen rib allograft for the reconstruction of bony mandibular defects in sheep. A pilot experimental study

A 6 cm bony defect in the mandible of 15 sheep, 8 years old, was reconstructed using variously allograft of frozen rib, rhOP-1 (rh BMP-7), platelet-rich plasma (PRP), and a combination of frozen rib allograft and rhOP-1. The histological, histomorphometric, immunohistochemical and radiographic features of reconstruction were analysed. The animals were euthanised at 2 months postoperatively. In the control and PRP groups, no bone formation was detected. The sheep receiving rhOP-1 showed some and those receiving both rhOP-1 and allograft showed most new bone formation; in both groups this was through endochondral and also fibrous ossification. The combination of bone allograft with growth factors demonstrated osteoconductive as well as osteoinductive properties, and is appealing in the management of problem fractures.