HISTOPATHOLOGIC ANALYSIS OF FAILED VASCULARIZED FIBULAR GRAFTS IN FEMORAL-HEAD OSTEONECROSIS

Salient histopathological features in 13 failed free vascularized fibu lar autografts implanted for osteonecrosis of the femoral head are doc umented. Of particular clinical and/or biomechanical relevance are 1-2 -mm-thick seams of viable lamellar bone bonded circumferentially to an atomically intact but necrotic graft cortices, which appear to preclud e their revascularization and remodeling. Surrounding the grafts are 3 -6-mm-thick rings of reactive bone, fused in many sites (average simil ar to 54%) to the osseous seams. They consist of a layer of sclerotic cortical-like bone melded with an outer layer of thickened cancellous bone. This remodeled reactive bone, largely the result of drilling, ap pears to buttress the grafts structurally and by inference, functional ly. Operative failures in all but one case are attributed primarily to collapse of the necrotic, fractured superior subtending segment of th e graft and of the subchondral plate secondary to size and progression of the osteonecrosis and superimposed osteoarthrosis. Morphological i ntegrity of grafts elsewhere and perifibular reactive sclerotic bone r emain unimpaired for up to 5 1/2 years. The salutary features of vascu larized autografts would appear to give them a decided advantage over their nonvascularized counterpart. (C) 1998 Wiley-Liss, Inc.