Posttraumatic bone defects around the knee

Larger bone defects around the knee are difficult to heal spontaneously. Therefore, surgical treatment is necessary to provide cells with osteogenic potential, an osteoconductive material, an osteoinductive stimulus, and a mechanically stable environment. Typically bone grafts are used for this and they can be autologous, allogeneic, xenogeneic or synthetic. Autologous bone grafts are a powerful means to fill bone defects. However, autologous bone for grafting is not an unlimited source in the body. For large bone defects, mostly more bone graft material is needed then can be harvested. Moreover, harvesting autologous bone grafts is associated with co-morbidities. Allogenic bone grafts are similar to autografts with the exception of the osteogenic ability. Due to treatment of the allograft, cells are removed to avoid immune reactions, but these are the osteogenic entities. Thus, an allograft is less potent than an autograft. Similar to allografts are xenografts. Finally, synthetic bone grafts can be obtained in different shapes and of different materials. Indications for using such grafts are large defects, during revision total knee arthroplasty and in high tibial osteotomies with opening angles larger than 10°