Cancellous impaction grafting in the human femur: histological and radiographic observations in 6 autopsy femurs and 8 biopsies

Abstract

6 whole postmortem femurs and 8 femoral biopsies were studied histologically, 3 months to 8 years after cancellous impaction grafting with a cemented stem for aseptic loosening. All stems were stable. Radiographs showed cortical healing in 5 cases, trabecular remodelling in 1, and trabecular incorporation in 9. There was a radiolucent line in 1 case. The histology varied. There was always a viable cortical shell around the grafted area. 1 patient showed complete bony restitution. The others still had varying amounts of remaining graft in the neo-medullary cavity, even after 8 years. The graft particles were usually embedded in dense fibrous tissue, thus forming a supporting composite tissue capable of carrying load. There was no time-dependent deterioration in the histological appearance. Radiographically, cortical healing and trabecular remodeling corresponded to viable bone. The lack of a radiolucent line said little about the viability of the tissue closest to the cement. The radiographs did not detect thin soft tissue membranes. Radiographic criteria used to assess primary total joint replacement do not necessarily apply to impaction grafting, and radiographic changes should be interpreted cautiously, especially as regards tissue viability.