Limb Salvage with Non-Expandable Endoprosthesis Reconstruction for Skeletally Immature Sarcoma Patients: A Retrospective Analysis

Background: Megaprosthetic limb salvage in skeletally immature patients with malignant bone tumors is complex due to growth potential, high complication risk, and uncertain long-term outcomes. This study evaluated survival, complications, limb-length discrepancy (LLD), and function after megaprosthetic reconstruction. Methods: We retrospectively reviewed 71 patients aged 10–18 years who underwent limb salvage with megaprosthesis between 2018 and 2024. Diagnoses included osteosarcoma (n=57) and Ewing sarcoma (n=14). Overall survival (OS), disease-free survival (DFS), local-recurrence-free survival (LRFS), and distant-metastasis-free survival (DMFS) were analyzed using Kaplan–Meier methods. Complications, revisions, LLD, functional outcomes (MSTS score, knee arc of motion), and limb status at last follow-up were assessed. Results: Median follow-up was 37 months (IQR 28; range 7–87). Estimated 5-year OS, DFS, LRFS, and DMFS were 82.6%, 60.4%, 86.0%, and 65.7%, respectively. Mean OS, DFS, LRFS, and DMFS were 76.1, 53.2, 70.5, and 56.8 months, respectively, with no significant differences between osteosarcoma and Ewing sarcoma. Most frequent complications noted in patients were neurological deficit n=10(14%), deep infection n=6(8%), wound dehiscence n=7(10%), and skin necrosis n=6(8%). Seven patients (9.9%) underwent revision surgery (8 procedures), predominantly for infection. LLD magnitude was 2–4 cm in 24/63 (38%), <2 cm in 22/63 (35%), and >4 cm in 2/63 (3%) with 15/63 (24%) having no LLD. At last follow-up, 64 patients (90.1%) retained limb reconstruction, while 7 (9.9%) had undergone amputation, primarily for local recurrence (n=5) or infection (n=2). Functional outcomes showed a mean knee arc of motion of 103° in femoral and 93° in tibial reconstructions, with corresponding MSTS scores of 24.8 and 23.2, respectively. Conclusions: Megaprosthesis provides satisfactory oncological outcomes in skeletally immature patients, although complication rates, amputation risk, and modest functional recovery highlight the need for careful patient selection and long-term surveillance.