Bone-grafting and bone-graft substitutes

The treatment of delayed unions, malunions, and nonunions requires restoration of alignment, stable fixation, and in many cases adjunctive measures such as bone-grafting or use of bone-graft substitutes. Bone-graft materials usually have one or more components: an osteoconductive matrix, which supports the ingrowth of new bone; osteoinductive proteins, which support mitogenesis of undifferentiated cells; and osteogenic cells (osteoblasts or osteoblast precursors), which are capable of forming bone in the proper environment. Autologous bone graft, usually harvested from the iliac crest, is an excellent graft material, but its availability may be limited and the procedure to harvest the material is associated with complications. Bone-graft substitutes can either replace autologous bone graft or expand an existing amount of autologous bone graft. Various forms of bone-graft substitutes are available and include allograft bone preparations such as demineralized bone matrix and calcium-based materials.