Outcome after treatment of osteoarthritis with open-wedge high-tibial osteotomy with a plate: 2-year results of a Japanese cohort study

Purpose: This prospective multicenter study evaluated patient reported outcomes (PROs) in individuals undergoing medial open-wedge high-tibial osteotomy (OWHTO) with plate stabilization compared to conservative care or no treatment. Methods: One hundred eighteen of 148 patients older than 40 years were elected for OWHTO with plate treatment. Thirty patients declined surgery and were followed as a conservative group. The primary outcome measure was the Knee Injury and Osteoarthritis Outcome Score (KOOS) at 2 years. Secondary measures included Oxford knee score, Western Ontario and McMaster Universities osteoarthritis index, range of motion (ROM), joint space width (JSW), femorotibial angle (FTA), and weight-bearing line ratio (WBLR). Results: Patient enrollment and baseline characteristics were heterogeneously distributed and led to group characteristics that were not comparable. Therefore, the comparison of the KOOS between the groups showing no differences must be treated with caution. In the OWHTO plate group, all PROs and the ROM significantly improved between baseline and 2-year follow-up. JSW remained stable in the OWHTO group. The FTA and WBLR significantly changed from a mean of 179.3 (95% confidence interval (CI): 178.7, 179.9) to 169.8 (95% CI: 169.2, 170.5) and from 23.1 (95% CI: 20.7, 25.5) to 62.4 (95% CI 59.0, 65.8), respectively. Treatment failure with conversion to total knee arthroplasty occurred in 1% of the OWHTO group; and in the conservative group, 10% converted to HTO or knee arthroplasty. Conclusions: OWHTO with plate leads to significant improvement of PROs and function 2 years after intervention and demonstrates reliable mechanical axis correction with subsequent shift of weight-bearing.