Short metaphyseal segments remaining after distal femoral tumor resection pose a unique challenge. Limb sparing options include a short stemmed modular prosthesis, total endoprosthetic replacement, cross-pin fixation to a custom implant, and allograft prosthetic composite reconstruction (APC). A series of patients with APC reconstruction were evaluated to determine functional and radiologic outcome and complication rates. Twelve patients were retrospectively identified who had a distal femoral APC reconstruction between 1994 and 2007 to salvage an extremity with a segment of remaining bone that was less than 20 centimeters in length. Seventeen APC reconstructions were performed in twelve patients. Eight were primary procedures and nine were revision procedures. Average f/u was 89 months. Twelve APC reconstructions (71%) united and five (29%) were persistent nonunions. At most recent followup 10 patients (83%) had a healed APC which allowed WBAT. One pt (8%) had an amputation and one pt (8%) died prior to union. Average time to union was 19 months. Four pts (33%) or five APC reconstructions (29%) required further surgery to obtain a united reconstruction. Although Distal Femoral APC reconstruction has a high complication rate, a stable reconstruction was obtained in 83% of patients. 1. Introduction Resection of large skeletal tumors can result in short metaphyseal juxtaarticular segments of host bone which can pose a reconstructive challenge to the musculoskeletal tumor surgeon. In addition, aseptic loosening or fracture around a standard reconstruction can lead to loss of bone stock so that only a short metaphyseal segment of host bone remains for fixation in revision surgery. Limb salvage reconstructive options in this scenario include the use of a standard endoprosthesis with fixation of the stem into the short segment of host bone, use of custom implants allowing for cross-pin fixation of the endoprosthesis to the host bone, use of an endoprosthesis to replace the entire bone, and use of a composite of an allograft and an endoprosthesis [1–3]. Use of a standard, modular endoprosthesis with cement or press fit fixation in this setting has not been directly investigated to our knowledge; however, the use of a short stem cemented into the metaphyseal segment would be expected to have a high rate of aseptic loosening due to the high stress imparted on the relatively short interface between host bone and cement [2] (Figure 1). Use of cross-pin fixation of a custom prosthesis to host bone has been described previously with a low rate of aseptic loosening
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