Distal Femoral Replacement in Nontumor Cases with Severe Bone Loss and Instability

Severe distal femoral bone loss and instability in revision TKA is challenging. We retrospectively reviewed 39 rotating-hinged distal femoral replacement devices in 37 patients to examine whether improved results were obtainable, using one design, over previously published results. The average age of the patients was 76 years (standard deviation, 10 years). Indications for distal femoral replacement included 11 revision TKAs, 13 periprosthetic fractures, 11 reimplantations, two complex primary TKAs, one distal femoral nonunion, and one acute distal femur fracture. Minimum followup was 24 months (mean, 46 months; range, 24-109 months). Eight patients died during followup. There were five reoperations: two patients with recurrent infection after two-stage treatment, one patient with a periprosthetic fracture treated by open reduction and internal fixation, one patient with late hematogenous infection, and one patient with bearing exchange to treat hyperextension. No failures from aseptic loosening were seen. Knee Society scores improved from 39 preoperatively to 87, and pain scores improved from 18 preoperatively to 43. Distal femoral prosthetic replacement with a tumor-type implant in severe cases provides excellent pain relief and function with a low short-term reoperation rate and an implant survivorship rate of 87% at 46 months. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.