Bone Morphogenesis of Rabbit Bone Morphogenetic Protein-Bound Hydroxyapatite-Fibrin Composite

Hydroxyapatite (HAP) and fibrin have been implanted in patients and observed to be well tolerated in orthotopic sites. This is a report on a composite of HAP, fibrin, and rabbit bone morphogenetic protein and insoluble noncollagenous protein (BMP-iNCP). Drill holes in the femoral condyles of rabbits were packed with granulated HAP (200 mg), fibrin (0.3 ml), BMP-iNCP (5 mg), or various combinations of the two. The fibrin consisted mainly of sterilized human fibrinogen and thrombin, and BMP-iNCP was prepared from demineralized rabbit cortical bone. New bone formation was observed at one, two, four, and eight weeks after implantation. The BMP-iNCP augmented new bone formation in rabbit femoral condyles. Fibrin made the composite easier to manipulate and did not inhibit osteogenesis at any period. The composites of HAP with BMP-iNCP and of HAP with BMP-iNCP and fibrin produced higher yields of new bone than fibrin alone or HAP alone.