Survival, failure modes and function of combined distal femur and proximal tibia reconstruction following tumor resection.

BACKGROUND: Tumor spread to the knee joint or skip metastasis to the adjacent bones of the knee require reconstruction with combined distal femur and proximal tibia replacements. The literature on implant survival and failure modes with this type of reconstruction is sparse. The goals of this study were to determine the implant survival, the different failure modes and the functional outcome of this megaendoprosthetic reconstruction.

PATIENTS AND METHODS: Thirty-nine patients with combined distal femur and proximal tibia reconstruction were retrospectively reviewed. Median follow-up was 8.8 years (quartiles 4.7-15.5 years). Twenty-one patients received combined distal femur and proximal tibia reconstruction as a primary mode of reconstruction, 18 patients as revision surgery after failed tumor prosthesis. For survival estimations, competing risk analyses were performed.

RESULTS: The revision-free survival at five years was 42% (95% CI 22%-56%) and implant survival with exchange of the original implant was 54% (95% CI 35%-68%). Five-year revision-free survival for soft tissue failure was 72% (95% CI 52%-84%), for infection 67% (95% CI 48%-80%), for structural failure 82% (95% CI 63%-91%), for aseptic loosening and tumor progression 97% (95% CI 82%-99%), respectively. Patients with revision surgery had higher risk for infection (p < 0.001), structural failure (p = 0.037) and shorter revision-free- (p = 0.025) and implant-survival (p = 0.006). Limb survival at 20 years was 94%. Mean musculoskeletal Tumor Society score was 76%.

CONCLUSION: Despite high failure rates with short revision-free survivals, combined distal femur and proximal tibia reconstruction achieved longtime limb survival in the majority of patients with satisfying function.