Dolph Houben

48 CHAPTER 2 Other complications Other complications include limb-length discrepancy, mal-union, and tumor reoccurrence. As many primary bone tumors affect children and adolescents, development and growth need to be taken into account and might lead to a limb-length discrepancy. Therefore, methods chosen must enable bone lengthening, whether by replacement of missing physis or some other method permitting reconstruction of limb length discrepancy [4, 82] . Another method of limiting limb length discrepancy involves epiphysiodesis of the contralateral limb. In tumor cases, local recurrence of the tumor is possible due to incomplete tumor resection or graft metastasis. Post-operative chemotherapy or radiation are frequently used methods to reduce the risk of local recurrence and distal metastasis. With increasing survival rates after limb-sparing surgery, a vascularized bone transfer can be safely performed after resection of primary malignant bone tumors [66, 82] . Mal-union is a relatively uncommon complication but might occur due to excessive ambulation or instability of the reconstruction, while the initial alignment had been satisfactory [72] . Future considerations The ability to safely use vascularized composite allotransplantation (VCA) would be a significant development in the reconstruction of large segmental bone defects. Allotransplantation of living bone or joint segments is a form of vascularized composite allotransplantation such a face, abdominal wall, and hand transplantation. Living bone allotransplants combine the ability to match defect size and shape, similar to cryopreserved banked bone, with the enhanced healing and remodeling potential of living bone [34, 47, 83-86] . Bone and joint VCA’s have been performed only sporadically in a clinical setting, due in part to the need for long-term immunosuppression. The risks and expense of drug immunotherapy are a major obstacle to their use. The use of immunosuppressive regimens needed for VCA cannot be justified in patients with nonlethal conditions. Long-term immunosuppressive regimens may be circumvented by replacing the allogenic bone circulation with a neoangiogenic autogenous blood supply. The autogenous neo-angiogenic circulation is created by implanting an autogenous arteriovenous bundle into the intramedullary space of a vascularized bone allotransplant (Fig. 7). This method would require only short-term immunosuppression. This method has proved to have potential in experimental models in our laboratory.