What Is the Survivorship of Megaprosthetic Reconstruction Following the Resection of Renal Cell Carcinoma Long Bone Metastases and What Are the Potential Risk Factors for a Prosthetic Complication?

Long bone metastases are common in patients with metastatic renal cell carcinoma (RCC). One potential surgical treatment option is resection and megaprosthetic reconstruction. However, implant complications and survival are poorly understood. This study analyzes patient and implant survival as well as associated risk factors. This is a retrospective study from a single academic center, analyzing 86 patients that underwent resection and megaprosthetic reconstruction performed between 1993 and 2017. The most common location of megaprosthetic reconstruction was the proximal femur (PFR) in 38% (33 of 86) of patients. We calculated overall patient survival and associated risk factors using the Kaplan-Meier method and implant survivorship using a competing risk analysis. A total of 73% (63/86) of patients died of their disease after a median of 19 (IQR 9-37) months following surgery, and a median of 71 (IQR 31-132) months after the initial diagnosis of RCC. The overall survival probability was 29% (95% CI 18-40%) five years after surgery. The five-year risk of revision surgery (within a competing risk framework) was 18% (95% CI 11-28). A total of 8% (7 of 86) of patients underwent an exchange of the implant itself. Patients with total bone replacements had a higher revision risk (SHR 19.46 (95% CI 6.9-54.9), < 0.01). Furthermore, the revision risk was higher with increasing reconstruction length per mm (SHR 1.01 (95% CI 1.01-1.02), = 0.03) and prolonged surgical time per minute (SHR: 1.01 (95% CI 1.0-1.02), < 0.01). Local postoperative radiation treatment (RTX) was associated with an increased risk for revisions (SHR 2.59 (95% CI 0.96-6.95), = 0.06). Modular megaprostheses demonstrated a fairly low risk of implant revision although postoperative radiation therapy and total bone replacements are associated with an increased risk.