Proximal Femoral Allograft-Prosthetic Composites: Do They Really Restore Bone? A Retrospective Review of Revision Allograft-Prosthetic Composites

Background: Large bone deficiencies are a challenging problem, historically treated with an allograft-prosthetic composite (APC) or megaprosthesis. There were several advantages of the APC compared with early megaprostheses, including the theoretical benefit of restoring bone stock. To our knowledge, there are no studies that have evaluated this claim. Our purpose was to review our institution's experience with APCs of the proximal femur that underwent revision for an aseptic cause and determine if the allograft bone was retained or removed during the revision procedure. Methods: We identified 203 proximal femoral allograft prosthetic composites placed from 1988 through 2014. Twenty-seven of these patients underwent a revision because of an aseptic cause. Three categories were devised to classify the amount of allograft retention: type A, complete allograft retention; type B, partial retention; and type C, no allograft retention. Results: The mean time from the initial APC to revision surgery was 5 years. The most common indication for revision included failure of the allograft (loosening or fracture). At the time of revision, there were 3 type A cases (11%), 4 type B cases (15%), and 20 type C cases (74%). Three of the 4 type B cases used the retained allograft as a strut graft around a newly inserted megaprosthesis. Conclusion: The results of this study are contradictory to previous literature that suggests APCs restore bone stock. In this series, the allograft was retained in only a small percentage of cases when the APC was revised for an aseptic cause. Level of Evidence: IV. (C) 2018 Elsevier Inc. All rights reserved.