Current use of biologic graft extenders for spinal fusion.

Use of biologic graft extenders in spinal fusions is increasing. Multiple allograft alternatives exist to the "gold-standard" autologous bone grafting. The ideal graft extender is osteoconductive, osteoinductive and has osteogenic potential. While the ideal graft extender has yet to be found, available bone graft extenders have varying degrees of predominantly osteoconductive and osteoinductive properties. This review will provide an update on available graft extenders including bone morphogenetic proteins, mesenchymal stem cells, and demineralized bone matrix. The goal is to provide a review of the current use in spinal fusions and future directions in biologics for spinal fusion.