Epiphysis distraction before surgery and fixation between the epiphysis and allograft bone during surgery. a) Type I of distal femur osteosarcoma (arrow point shows the gap between osteosarcoma and the epiphyseal plate >2 cm). b) Type II of distal femur osteosarcoma (arrow point shows the gap between osteosarcoma and epiphyseal plate <2 cm). c) Gross view of epiphysis distraction by an external fixator. d) X-ray of epiphyseal distraction by an external fixator(arrow point shows the metaphyseal and epiphyseal plate were completely separated). e) Appearance of proximal epiphysis section (arrow point indicates a cross section of the proximal end of the epiphysis was irregular sawtooth shaped). f) Appearance of tumor bone after resection (the interval between osteotomy level and tumor border was no less than 5 cm). g) The distal part of the allograft bone was trimmed to be consistent with the proximal epiphysis. h) Appearance after fixation between the epiphysis and allograft bone (arrow point shows the fixation of cartilage and allograft bone by lag-screw of cancellous bone).