Substitutes for autologous bone graft in orthopaedic trauma.

Although bone grafting has a well-recognised role in orthopaedic surgery for the treatment of nonunion, bridging diaphyseal defects and filling metaphyseal defects, it is associated with postoperative pain and morbidity. When extensive grafting is required, as in spinal arthrodesis and the management of large bony defects, inadequate amounts of autologous bone may not be available. Allograft bone has been used as an alternative but it has low osteogenicity, increased immunogenicity and resorbs more rapidly than autogenous bone; transmission of disease remains a concern. Autogenous bone graft is osteogenic, osteoinductive, osteoconductive and completely biocompatible. These characteristics should be present in the ideal substitute. Osteogenic materials have the inherent capacity to form bone, which implies that they have living cells such as osteocytes or osteoblasts, capable of producing it. Osteoinductive materials stimulate cells in the wound or the local environment to undergo phenotypic conversion to osteoprogenitor cell types capable of formation of bone. Osteoconductive materials have no capability to form bone or induce its formation. They merely provide an inert biocompatible scaffold, which local osseous tissue can utilise to regenerate living bone. There is no substitute for bone-graft yet available which embodies all these qualities. To date most of the available materials have tended to be either predominantly osteogenic or osteoinductive, or purely osteoconductive. This article reviews the substitutes which are commonly available and considers the clinical evidence to support their use in the management of orthopaedic trauma. Osteogenic and osteoinductive materials