Osteogenic Protein-1 in Knee Arthritis and Arthroplasty

The use of graft materials to restore bone stock and promote healing and implant stabilization is a crucial part of total knee arthroplasty, especially in revision surgery. Recent research has centered on the use of osteoinductive materials to promote bone formation. Osteogenic proteins are members of a superfamily of proteins called transforming growth factor-beta that, either alone or in combination with other regulatory molecules, induce new bone formation. The cloning and genetic expression of recombinant human osteogenic proteins has led to production of quantities sufficient for their clinical use. Recombinant human osteogenic protein-1 has been combined with bone-derived Type I collagen for delivery to an implant site. Preclinical studies have shown that the osteoinductive capacity of autograft and allograft bone and bone graft substitute materials can be notably improved with the addition of osteogenic protein-1. The use of this protein consistently improved the amount and rate of new bone formation compared with graft alone, resulting in earlier graft incorporation and consolidation. In addition, because osteogenic proteins are chondrogenic, they also may have a role in the treatment of cartilage injury and degeneration. Osteogenic protein-1 has been shown to induce hyalinelike cartilage repair of full thickness osteochondral defects in animal models with no degradation of the tissue with time. Although no detailed clinical studies in knee surgery have been reported with the use of osteogenic protein-1, in anecdotal cases its use alone and with bone graft materials indicate results consistent with those obtained in preclinical studies.