Long-term outcomes of limb salvage treatment with custom-made extendible endoprosthesis for bone sarcoma around the knee in children

Background Limb salvage for bone sarcoma around the knee in skeletally immature children is challenging because of interference on two critical growth plates in the lower limb. This retrospective study aims to evaluate long-term outcomes and influence on growth of the lower limb of the cemented extendible endoprostheses. Methods Forty-five children with bone sarcoma around the knee, who underwent custom-made extendible endoprosthesis replacements, were included in this study. The average follow-up was 10.1 years. Survival, prosthetic-related complications and revision, functional outcomes, and influence on growth by prosthesis implantation were recorded. Results The 5-year disease-free survival and overall survival are 54.9% and 72.7%, and the 5-year prosthesis survival rate is 59.4%. The prosthesis was extended 4.2 cm in average. Limb length discrepancies of 20 patients were within 2 cm, and growth inhibition of proximal tibial epiphysis by passive implant insertion was observed. Aseptic loosening in 7 patients was the most significant complication. The Musculoskeletal Tumor Society score at last visit was 83.2%. Conclusions The use of custom-made extendible endoprosthesis provided good functional results for children with bone tumor around the knee. Further improvement of the prosthesis design and operation technique will help to decrease complication and gain better limb function.