Cemented Distal Femoral Endoprostheses for Musculoskeletal Tumor: Improved Survival of Modular versus Custom Implants

BACKGROUND Advocates of newer implant designs cite high rates of aseptic loosening and failure as reasons to abandon traditional cemented endoprosthetic reconstruction of the distal femur. QUESTIONS/PURPOSES We asked whether newer, modular distal femoral components had improved survivorship compared with older, custom-casted designs. PATIENTS AND METHODS We retrospectively reviewed 254 patients who underwent distal femoral endoprosthetic reconstruction. We excluded two patients with cementless implants, 27 with expandable prostheses, and 39 who had a nontumor diagnosis. This left 186 patients: 101 with older custom implants and 85 with contemporary modular implants. The minimum followup was 1 month (mean, 96.0 months; range, 1-336 months). The tumor was classified as Stage IIA/IIB in 122 patients, Stage IA/IB or benign in 43, and Stage III or metastatic in 21. RESULTS Kaplan-Meier analysis revealed overall 10-, 20-, and 25-year implant survival rates of 77%, 58%, and 50%, respectively, using revision of the stemmed components as an end point. The 85 modular components had a greater 15-year survivorship than the 101 custom-designed implants: 93.7% versus 51.7%, respectively. Thirty-five stemmed components (18.8%) were revised for aseptic loosening in 22 patients, implant fatigue fracture in 10, infection in two, and local recurrence in one. CONCLUSIONS Cemented modular rotating-hinge distal femoral endoprostheses demonstrated improved survivorship compared with custom-casted implants during this three-decade experience. Patients with low-grade disease and long-term survivors of high-grade localized disease should expect at least one or more revision procedures in their lifetime. LEVEL OF EVIDENCE Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.