[Biological background of clinical bone transplantation]

The biologic incorporation of bone grafts into host bone is dependent upon the type of graft, but the aim in all cases is to replace the graft with host bone by bone resorption and new bone formation. This is best achieved by transplanting fresh autogeneic bone. Allogeneic bone grafts are less efficient because of immunological reactions to the grafts, but they are the only alternative in clinical practice. There are several methods of preparing the allogeneic grafts to make them more suitable for clinical use, e.g. deep-freezing, freeze-drying, or demineralization. Experimentally attempts have been made to reduce the immunological reactions to allogeneic bone, or to combine the graft with bone-inducing substances. The basic knowledge of bone transplant biology has improved greatly in recent years, but is still inadequate to achieve an improvement in the established clinical practice.