Background: Limb preservation in musculoskeletal tumor surgery has largely replaced amputation. Biologic reconstructions are now performed as preferred choice; if not feasible options are “megaprostheses”, allografts or composites. Endoprosthetic reconstructions usually provide immediate function, but fail at long term. Osteochondral allografts allow for one-to-one restoration and have potential for incorporation; however degeneration of the cartilage requiring revision almost inevitably will occur. In most cases, revision is then done by endoprosthetic replacement. Aim: In our patients, resurfacing of retained allografts failed. Problems encountered are presented and solutions proposed. Case Presentation: Resurfacing over retained allografts in the 2 index cases has resulted in failures related to fractures and instability. Revision with massive constrained endoprostheses was needed. Based on the experience with these failures, primary endoprosthetic replacement anchored in vital bone in a following case resulted in stable function. Conclusion: Knee replacement for advanced degeneration of the osteochondral allograft apparently needs choosing increased femoro-tibial constraint systems and stem extensions anchored to vital host bone.
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