Repair of long intercalated rib defects using porous beta-tricalcium phosphate cylinders containing recombinant human bone morphogenetic protein-2 in dogs

A new method to repair rib defects with biomaterials containing recombinant human bone morphogenetic protein-2 (rhBMP-2) is presented in this report. We had reported previously the successful regeneration of bony rib defects by placing a short chain of small beta-tricalcium phosphate (β-TCP) cylinders on the intact periosteum. The multi-cylinder implants were ineffective in promoting rib repair when the periosteum was absent. By adding rhBMP-2 to the β-TCP cylinders, we were able to promote rib bone regeneration in the presence or absence of the periosteum. The osteogenic capacity of the rhBMP-2/β-TCP composite implant and the time required to complete regeneration were evaluated in a canine model. An 8 cm long section of rib bone, including the periosteum, was removed and replaced with a chain of the rhBMP-2/β-TCP cylinders. At 6 weeks after implantation, the ribs were restored to their original configuration and mechanical strength. The multi-cylinder β-TCP implants were degraded and replaced by new bone in 12 weeks. This new degradable bone-inducing implant material has significant clinical potential for rib repair.