Role of osteogenic protein-1/bone morphogenetic protein-7 in spinal fusion

Justin Munns, Daniel K Park, Kern Singh

Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois, USA

Abstract: Osteogenic protein-1 (OP-1), also known as bone morphogenetic protein-7 (BMP-7), is a protein in the TGF-β family of cellular proteins that has shown potential for application in patients undergoing spinal fusion due to its proven osteoinductive effects, particularly in patients with spondylolisthesis. OP-1 initiates numerous processes at the cellular level, acting on mesenchymal stem cells (MSCs), osteoblasts, and osteoclasts to stimulate bone growth. Animal studies of OP-1 have provided strong evidence for the ability of OP-1 to initiate ossification in posterolateral arthrodesis. Promising findings in early clinical trials with OP-1 prompted FDA approval for use in long bone nonunions in 2001 and subsequently for revision posterolateral arthrodesis in 2004 under a conditional Humanitarian Device Exemption. Larger clinical trials have recently shown no notable safety concerns or increases in adverse events associated with OP-1. However, a recent clinical trial has not conclusively demonstrated the noninferiority of OP-1 compared to autograft in revision posterolateral arthrodesis. The future of OP-1 application in patients with spondylolisthesis thus remains uncertain with the recent rejection of Premarket Approval (PMA) status by the FDA (April 2009). Further investigation of its treatment success and immunological consequences appears warranted to establish FDA approval for its use in its current form.

Keywords: osteogenic protein-1, bone morphogenetic protein-7, spinal fusion