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Reconstruction of the femur depends on the quantity of bone loss and the quality of the remaining bone stock. Multiple classifications and reporting systems can be used to characterize the bone defect. We present a simple algorithmic approach for proximal femoral bone loss reconstruction during revision total hip arthroplasty. Quantity of bone loss is assessed using radiographs based on different classification systems, whereas quality of the remaining bone stock is assessed intraoperatively. Based on the type of proximal bone loss and the quality of the available bone, we describe our preferred reconstruction technique. For minor bone loss, the metaphysis is expanded but intact with partially absent calcar. There is minimal bone loss anteriorly and posteriorly, and the diaphysis is intact. For significant bone loss, the metaphysis is compromised, and there is no calcar. There is minimal bone loss anteriorly and posteriorly. The available proximal bone may be thin, sclerotic, and incapable of support. However, the diaphysis is intact. For massive bone loss, there is complete circumferential bone loss in the metaphysis, extending to the diaphysis. The anterolateral bone and supporting subtrochanteric metaphyseal bone are absent. The metaphysis is not stable and will not offer rotational stability. There is massive bone loss anteriorly and posteriorly. The stability of the implant is dependent on distal diaphyseal fixation. For complete proximal bone loss, there is extensive circumferential segmental bone loss proximally and extensive cavitary loss involving the entire diaphysis. Additionally, there is extensive ectasia of the diaphysis.

During preparation for uncemented femoral arthroplasty, a phenomenon has been observed that indicates thinning of anterior metaphyseal bone to a critical level. Light can be seen from within the canal passing through the anterior cortex. This skylight sign alerts the surgeon that a cortical defect or fracture can occur on reaming, broaching, or component insertion. In 420 consecutive arthroplasties, a skylight sign was noted in 97 (23%) hips. In 5 of those hips an oval cortical defect was created and in 3 hips a fracture occurred during broaching or insertion. Loosening developed in 1 hip with fracture. No fractures or defects occurred in hips without a skylight sign. If a skylight sign is present, the femur is at risk and preventive measures should be taken.

Educational Objectives: As a result of reading this article, physicians should be able to: 1. Identify the available types of reconstruction for failed total hip arthroplasty. 2. Summarize the preoperative workup of patients with failed total hip arthroplasty and massive proximal femoral bone loss. 3. Assess the surgical technique of proximal femoral replacement for failed total hip arthroplasty. 4. Recognize treatment complications, patient outcomes, and survival of proximal femoral megaprostheses for revision of failed total hip arthroplasty. Despite recent advances in device manufacturing and surgical techniques, the management of proximal femoral bone loss in revision total hip arthroplasty remains challenging. Currently, failed total hip arthroplasty in elderly and less active patients, nonunion of the proximal femur with multiple failed attempts at osteosynthesis, resection arthroplasty, and massive proximal femoral bone loss can be salvaged with proximal femoral replacement using a megaprosthesis. The procedure is technically demanding and requires careful preoperative planning. Instability and aseptic loosening are the major complications, especially in younger and more active patients. The new generation of modular proximal femoral replacement megaprostheses and the increased experience obtained with these surgeries have reduced complication rates and improved outcomes., (Copyright 2014, SLACK Incorporated.)