Fig. 1

Preoperative standing anteroposterior radiographs of the full-length lower limb. A-E pre-simulation, F–H post-simulation. For simulation, the weight bearing line (WBL) was drawn from the center of the femoral head to 62.5% of the width of the tibial plateau (Fujisawa point). The distal tibia was rotated till the WBL passed through the 62.5% coordinate. A WBL ratio: The WBL was drawn from the center of the femoral head to the center of the dome of the talus. The WBL ratio was defined as a ratio of the tibial width which is measured from the medial side to the lateral side. B Pre-simulation (*) / G post-simulation femorotibial angle (FTA): FTA was defined as a lateral angle between the femoral anatomical axis and the tibial anatomical axis. B Neck shaft angle (**) was defined as an angle between the midline drawn in the femoral neck and the femoral anatomical axis. C Pre-simulation (*) / H post-simulation (*) hip-knee-ankle axis (HKA) angle: HKA was formed by the mechanical axes of the femur and tibia. C Pre-simulation mechanical lateral distal femoral angle (mLDFA) (**) was defined as the lateral angle between the mechanical femoral axis and an articular tangential line of the distal femur. C Pre-simulation (***) / H post-simulation (**) mechanical medial proximal tibial angle (mMPTA) was defined as the medial angle between the mechanical tibial axis and an articular tangential line of the proximal tibia. C Pre-simulation joint line convergence angle (JLCA) (****) was defined as the angle between an articular tangential line of the distal femur and an articular tangential line of the proximal tibia. D Coronal femoral/tibial bowing: the femoral diaphysis was divided into four equal parts, and the midpoint of the endosteal intramedullary canal was depicted in each quarter. The angulation between midlines drawn in the proximal and distal quarters of the femoral diaphysis was measured. The tibial diaphysis was divided into three equal parts, and the angulation between midlines drawn in the proximal and distal thirds of the tibial diaphysis was measured. E Pre-simulation lower leg length (*) was defined as the distance between the center of the femoral head and the center of the dome of the talus. E Femoral leg length (**) was defined as the distance between the center of the femoral head and the most proximal point of the femoral notch. E Pre-simulation tibial leg length (***) was defined as the distance between the midpoint of the tibial spines and the center of the dome of the talus. F Opening gap (*) and opening angle (**) were measured