Non-neoplastic indications and outcomes of the proximal and distal femur megaprosthesis: a critical review

PURPOSE: Megaprosthesis or endoprosthetic replacement of the proximal and distal femur is a well-established modality for treatment of tumors. The indications for megaprosthesis have been expanded to the treatment of some non-neoplastic conditions of the knee and hip, with the severe bone loss associated with failed arthroplasty, communited fractures in the elderly with poor bone quality, and resistant non-union. Th aim of this study is to find out whether megaprosthesis of the knee and hip is successful in the treatment of non-neoplastic condtions. The study comprises a review of the indications, complications, and outcomes of megaprosthesis of the proximal and distal femur in non-neoplastic conditions of the knee and hip joints. METHODS: We extensively reviewed the literature on non-neoplastic indications for megaprosthesis of the proximal and distal femur after performing a detailed search of the Pubmed database using the medical subject heading (MeSH) terms ‘proximal femur replacement’ or ‘distal femur replacement’ and ‘hip or knee megaprosthesis.’ The data obtained after the structured search were entered into a Microsoft Excel spreadsheet. The frequency distribution of the demographic data, indications, complications, and outcome was calculated. RESULT: We included ten studies (seven proximal femur replacement and three distal femur replacement) of 245 proximal femur and 54 distal femur mega prostheses for treatment of non-neoplastic conditions. Bone loss in failed arthroplasty, either due to periprosthetic fracture or deep infection, was the most common indication for megaprosthesis. Dislocation was the most common complication after proximal femur megaprosthesis, and infection was the leading cause of complications after distal femur megaprosthesis. CONCLUSION: Megaprosthesis for treatment of non-neoplastic conditions around the distal and proximal femur is a viable option for limb salvage, with an acceptable long-term outcome. Although the complications and survival rates of megaprosthesis in non-neoplastic conditions are inferior to a primary arthroplasty of the hip and knee but are comparable or better than the mega prosthetic replacement in the neoplastic conditions. Proximal femoral megaprosthesis has higher dislocation rates and requirement for revision compared to distal femoral megaprosthesis. However, the proximal femoral megaprosthesis has lower rates of infection, periprosthetic fractures, and soft tissue complications, as compared to distal femoral megaprosthetic replacement. Both associated with aseptic loosening but not statistically significant.