Fig. 1

Simulated osteotomy. Lower limb 3D model was built with CT scanning data by medical image processing software and then loaded into the medical design software. The parameters of medial OWHTO were set including cutting point, lateral hinge, sawing direction, sawing depth, and correction angle. The distraction of the medial opening wedge was calculated by the "Miniaci” method according to the rotating degree of the target lower limb force line from the trigonometric perspective (a, b). The position of the lateral hinge was suggested to be about 5–10 mm from the lateral edge of the tibia plateau (c, d)