FUTURE OF MASSIVE RECONSTRUCTION WITH BON E ALLOGRAFTS AFTER MASSIVE BONE RESECTION FOR TUMORS

Currently cryopreservation offers the best means of preserving bone ti ssue for allografts. At -196 degrees C all enzyme activity is halted a nd tissue preservation is unlimited. Perfect sterilization, adapted cr yoprotection and controlled freezing and thawing are now part of the w ell-controlled process of bone preservation in bone banks. At implanta tion, the mechanical properties of cryopreserved bone is as good as or better than fresh bone, although the diaphyseal cortical bone is more fragile. Anatomic and physiologic reconstruction of the graft area is a major factor in graft resistance. It takes approximately three week s for vessels to penetrate cancellous allografts and at least one mont h for total revascularization. The delay may reach several years for c ortical bone. The immune response of the host is determined by the ant igenic properties of the leukocytes in the bone marrow as well as the blood vessels and nerves. The protein-mineral complex itself has littl e antigenic effect. A certain number of nonspecific immune reactions r esult from transfusions almost always performed with bone grafting. At the present time, there is no artificial material capable of providin g a mechanically acceptable substitute for allograft bone in limb reco nstruction. Allograft bone currently stocked in bone banks provides a biologically and clinically acceptable means of reconstruction after m ajor bone loss. Other factors such as public acceptance and administra tive authorizations will also play an important role in the future of massive reconstruction with bone allografts.