Dolph Houben

32 CHAPTER 2 The Clinical Problem Large segmental bone defects cause significant disability in patients after limb-sparing surgery. Segmental bone loss is often the result of trauma, primary malignant tumor resection, meta-static tumor resection, infection, failed primary reconstruction, or congenital pseudarthrosis. Treatment of these large bone defects is a challenging problem. The eventual goal of limb-sparing surgery is to preserve limb function and prevent amputation. All current treatment options have their specific advantages and disadvantages. The current state of treatment options Although amputation remains an option for treatment of segmental bone loss, reconstruction of the bony defect is often to be preferred. Limb function can generally be restored when tissue loss for whatever reason spares critical neurovascular structures. Methods used to restore gaps in structural bone include vascularized bone transfer (commonly fibula or iliac crest [1-4] ), bone transport, the Masquelet technique [5] , prosthetic replacement, re-implantation of autoclaved tumor bone and structural and osteoarticular allograft bone, used alone or in combination with other methods. Allografts segments are frequently used to reconstruct large segmental defects. They are readily available and selected to match defect size and shape. With internal fixation, they provide desirable immediate stability. Over time they remain largely necrotic and are therefore susceptible to infection, non-union, and late stress fracture [6, 7] . Bone transport will close only modest bone segmental gaps, with healing times of 1-3 years [8] . Custom endoprosthetic replacement provides immediate function, but with limited endurance [9] . The complexity of reconstruction by any technique does not surprisingly result in higher rates of complications than those of amputation. For example, prosthetic failure rate reports range from 33% to 100 %, mostly due to mechanical failure and/or infection, requiring revision or amputation [10-12] . Allograft/ prostheses hybrids have also generally failed, with frequent implant loosening, allograft fracture, nonunion, or infection [13-15] . The re-use of autoclaved tumor bone risks incomplete tumor death and an incidence of a stress fracture and infection greater than cryopreserved allograft bone [11, 12] . History of the (Vascularized) Bone Grafts Bone autografts, allografts, and vascularized bone grafts are currently widely used for the reconstruction of large segmental defects. The history of bone grafts is ludicrous and cruel. The use of bone grafts for the treatment of bone defects was first described in 1668 by a Dutch surgeon Job van Meekeren [16] . He described the first procedure of using a bone graft. This bone graft was derived from a dog’s skull. He implanted the bone segment in a traumatic bone defect of a soldier's cranium. In the 17 th century, this method was considered unchristian and the patient was excommunicated. For this reason, the soldier asked the surgeon Job van Meekeren to remove the bone graft, although by this time the bone graft was already healed. The idea of bone grafting has been invented by the Dutch scientist Antoni van Leeuwenhoek [17] . The French scientist Ollier experimented with bone grafts on rabbits and dogs and concluded that bone autografts are viable. He recognized that separated bone fragments could survive in a suitable environment without periosteum [18] . In more recent decades, several experimental and clinical