The stability of osteosyntheses bridging defects.

Segmental defects of 2 cm in the femoral midshaft of dogs were bridged with either single, double or a single plate and cortical bone graft. The massive bone transplant was fixed with screws opposite the plate in order to diminish harmful bending loads. The biomechanical behavior was tested under continuous increasing axial stress. The combined osteosynthesis of internal plate and contralateral cortical bone graft fixation increased the stability in the defect region significantly (see Figs. 3 and 4). The results of our tests are discussed with respect to the basic problem that the biological behavior of transplanted cortical bone depends mainly on absolute stability in the transplanted area. We think--although the transplantation of autologous cancellous bone should be favoured--the transplantation of massive bone grafts still has its indications under well defined conditions particularly when good mechanical stability is present.