BackgroundWe hypothesized that hemiarthroplasty with a synthetic device in skeletally immature patients with osteosarcoma around the knee would be functional due to high adaptability in the pediatric age group, and may decrease the number of surgeries until limb equalization by preserving the nearby physis. MethodsWe analyzed the outcomes of 25 hemiarthroplasties (12 distal femur, 13 proximal tibia). Average patient age was 11.8 years. We assessed (1) whether hemiarthroplasty could be considered as a viable option and could preserve growth of the nearby physis, and (2) whether these patients could reach the final goal of adult-type tumor prosthesis implantation within a preplanned number of surgeries. ResultsThree (12%) of 25 hemiarthroplasties showed failure. Average Musculoskeletal Tumor Society functional score of 23 patients was 25.1. Average tibial and femoral shortening for the corresponding reconstruction was 0.3cm and 0.5cm, respectively. In terms of number of surgeries for limb equalization, 19 patients (76%) had less, four (16%) had equal, and two (8%) had more surgeries than planned. ConclusionsHemiarthroplasty is a sound option until skeletal maturity, allowing surgeons to choose the appropriate procedure based on the patient's growth status, and may reduce the amount of shortening by preserving nearby physis. J. Surg. Oncol. 2015 111:107-114. (c) 2015 Wiley Periodicals, Inc.