We report a method of femoral varus osteotomy performed with the threadwire saw in three patients. The purpose was prevent proximal femoral fracture and perform the proximal femoral osteotomy precisely. Richard et al. reported fourteen complications of proximal femoral fractures occurring in 157 patients; Peter J. et al. reported sixteen complications in 79 patients. We performed femoral varus osteotomy with the threadwire saw, and no complications occurred in our patients. The average age of patients at operation was 8 years (range 2 to 13 years). The average follow-up was 1 year 7 months (range 1 year 2 months to 2 years 3 months). All patients underwent operation of the left hip joint. Avulsion fracture of the lesser trochanter occurred easily with the chisel, and the risk of damage to the femoral nerve, artery, and vein were high when varus osteotomy of the femur was performed. Osteotomy using a T-saw produces bone cross section smooth, allowing the medical cortical bone to be arranged in order. We conclude that use of the threadwire saw for femoral osteotomy does not cause avulsion fracture and damage to the femoral nerve, artery, vein and tendon of the iliopsoas muscle.
