Medial opening wedge high tibial osteotomy: a prospective cohort study of gait, radiographic, and patient-reported outcomes.

To evaluate the effect of medial opening wedge high tibial osteotomy on gait, radiographic, and patient-reported outcomes over a 2-year postoperative period in patients with varus alignment and medial compartment knee osteoarthritis, and to identify significant predictors of outcome. We used an observational cohort study design and prospectively administered 3-dimensional quantitative gait analysis, hip to ankle weight-bearing radiographs, and patient-reported outcomes preoperatively and 6, 12, 18, and 24 months postoperatively. Observed changes with 95% confidence intervals (95% CIs) were calculated. Multivariate linear regression and cluster analysis were used to evaluate associations between patient characteristics and 2-year outcomes in dynamic knee joint load (external knee adduction moment during gait) and Knee Injury and Osteoarthritis Outcome Scores (KOOS). A total of 126 patients (mean age 47.48 years) were included in the study. Mean changes suggested clinically important improvements in malalignment (change in mechanical axis angle 8.04 degrees [95% CI 7.16 degrees , 8.93 degrees ]), medial compartment load during gait (change in knee adduction moment -1.38 [95% CI -1.53, -1.22] percentage body weight x height), and all KOOS domain scores (change in pain 23.19 [95% CI 19.49, 26.89] KOOS points). A small (13%) increase in knee adduction moment was observed from 6 to 24 months postoperatively. Few preoperative clinical and/or gait characteristics assessed at baseline were significantly associated with 2-year outcomes. A medial opening wedge high tibial osteotomy with correction to approximately neutral alignment produces substantial and clinically important changes in dynamic knee joint load and patient-reported measures of pain, function, and quality of life 2 years postoperatively. Changes in knee adduction moment observed in the first 2 years postoperatively should be explored as potential predictors of longer-term success and subgroups of patients with poor outcomes.