A seven-year-old girl with osteosarcoma of the proximal tibia who underwent rotationplasty type A II. Bony consolidation was seen at 3 months postoperatively. She maintained an excellent functional outcome and quality of life into adulthood with an MSTS functional score of 93.33% and a global quality of life score of 91.67%. 2-A Preoperative plain radiograph. 2-B Plain radiograph showing union of the tibia to the femoral stump. 2-C Photographs taken with the prosthesis fitted in place showing an active range of motion of the “knee” of 85°.