High tibial osteotomy effectively restores motor function during daily activities in patients with knee osteoarthritis and varus deformity

Purpose: This study evaluated the effects of high tibial osteotomy (HTO) on spatio-temporal parameters, kinematics and kinetics during walking, stair ascent and descent, in patients with medial knee osteoarthritis and varus malalignment, by using a prospective randomized case-control design, which compares the effects of HTO with a non-surgical conservative treatment. Methods: A total of 49 patients with medial knee osteoarthritis and varus malalignment were enroled in a prospective randomized case-control study. Patients were randomly assigned to the Surgical Group (n = 25), which underwent open-wedge HTO, or the Conservative Group (n = 24), which followed non-surgical conservative treatment. An additional 20 healthy subjects were included as controls. Radiographs in double-leg stance and gait analysis during the motor activities were conducted at baseline and follow-up. Statistical comparisons of spatio-temporal parameters, joint rotations and joint moments were performed to assess the effects of surgery on motor function. Results: In the Surgical Group, HTO significantly corrected the tibiofemoral angle (from 8.3 ± 3.3° to 0.9 ± 2.4°, p < 0.001), restoring values comparable to healthy controls. Knee and ankle adduction were fully restored in all motor tasks, with significant improvements in at least 60% of the movement cycle (p < 0.05). Knee adduction and rotation moments were significantly reduced, with some patients even showing lower-than-normal knee adduction moments during walking, suggesting possible overcorrection. However, pelvic obliquity and ankle flexion remained altered, and no significant changes were observed in walking speed or stride length. The Conservative Group showed no improvements at follow-up. Conclusions: HTO effectively restores knee alignment and major motor function parameters during walking and stair tasks, whereas non-surgical conservative treatments do not lead to any improvement. However, some residual motor function deviations persist after surgery, suggesting that certain biomechanical adaptations may remain after surgical correction. Level of Evidence: Level I, randomized controlled trial.