Current Strategies for Limb Salvage and Reconstruction in Pediatric Lower Extremity Malignant Bone Tumors: Focus on Growth Preservation and Functional Outcomes.

Background/Objectives: Osteosarcoma and Ewing sarcoma are the predominant malignant bone tumors of the lower limbs in children. With 5-year survival rates of 70-77% for localized disease, limb salvage with growth-compatible reconstruction has replaced amputation as the standard. This review aimed to synthesize current reconstruction strategies, propose an age-and defect-based decision algorithm, and highlight growth-preserving innovations for skeletally immature patients. Methods: This narrative review of surgical techniques-including rotationplasty, biological reconstruction (vascularized/non-vascularized fibula, allograft, recycled autograft, "hot dog" composite), bone transport, and endoprosthetic replacement (modular, extendable, 3D-printed)-was conducted, with a literature search covering January 1990 to October 2025 and emphasized pediatric studies published after 2020, emphasizing pediatric outcomes, complication profiles, and functional scores. Results: Across pediatric and mixed-age cohorts (typically n ≈ 10-30 per technique; median follow-up 3-10 years), rotationplasty demonstrated high durability with Musculoskeletal Tumor Society (MSTS) scores of 21-28/30, especially in children < 6 years. Biological reconstruction achieved >80% union in defects < 6 cm, while vascularized fibula grafts yielded 82-95% union for 6-15 cm defects. Bone transport produced reliable union for 3-15 cm defects but required prolonged fixation (40-60 days/cm) and had high pin-tract infection rates (50-60%). Extendable endoprostheses demonstrated 5-year prosthesis survival of 54-87%, while early joint-preserving 3D-printed implants improved MSTS scores from 17 to 28 points in a pediatric series (n = 7, mean follow-up 30 months). Conclusions: Personalized reconstruction guided by a child-centered algorithm optimizes oncologic control, skeletal growth, and long-term function. Emerging 3D-printed joint-preserving implants and noninvasive lengthening technologies promise further reduction in revisions and complications in pediatric limb salvage.