Custom megaprosthesis for the management of a failed total ankle replacement with massive cortical osteolysis

Ankle arthritis is a common, debilitating condition. Total ankle replacement (TAR) has become a popular management option for end stage ankle arthritis. Aseptic loosening is the most common mechanism for implant failure. Third body-mediated inflammatory bone resorption, such as metallosis, is a described mechanism of aseptic loosening. Metallosis can result in massive cortical lysis. Standard revision TAR is not a viable option in the setting of massive cortical osteolysis. The authors present a case of a 67-year-old female,15 years post-primary TAR, presenting with a failed TAR secondary to periprosthetic osteolysis due to metallosis. She was managed with staged revision. The first stage included implant removal, biopsy, debridement, and cement spacer insertion. Histology diagnosed aseptic loosening due to metallosis. Due to massive cortical osteolysis and poor bone stock, the second stage procedure was a custom total ankle megaprosthesis. At the 2-year follow-up, the patient had regained pain-free function, and the AOFAS score improved from 18 to 97. Cortical osteolysis in the setting of a failed TAR makes revision TAR surgery impossible using off-the-shelf revision implants. We describe the successful management of this pathology using a custom-made total ankle megaprosthesis, with good clinical outcomes at two years. Routine clinical and radiographic follow-up is critical following TAR. Level of evidence V, Case Study