Fig. 1

Alignment line group. Preoperative planning (A). The preoperative WBL was measured by mechanical axis a. B Targeted alignment line b was drawn according to the target WBL. C A frame was created and rotated until the ankle joint center was on the targeted mechanical axis b, and the rotation angle of the frame was measured. Surgical correction (D). A metal wire was positioned at the center of the hip joint and the ankle joint, confirming that the metal wire passed through the intersecting point of the targeted WBL. Postoperative evaluation (E). The postoperative WBL was measured by mechanical axis c one year after surgery