Abstract
BACKGROUND: This study investigated whether the preoperative joint line convergence angle (JLCA) influences post-operative correction accuracy and clinical results in knee osteoarthritis (KOA) patients undergoing medial open-wedge high tibial osteotomy (MOWHTO). METHODS: A total of 169 knees that underwent MOWHTO were followed up for a minimum of 2 years. Preoperative and 2-year postoperative radiographic parameters were used to measure JLCA and the hip–knee–ankle angle (HKA). A post-operative HKA valgus of 0–4° was defined as accurate correction; values outside this range were considered abnormal. Clinical efficacy was evaluated with the Hospital for Special Surgery (HSS) knee score. Multivariate linear regression was performed to identify factors that affected the post-operative HSS scores. RESULTS: The cohort comprised 169 knees (34 male, 135 female patients; mean disease duration 6.60 (5.80, 7.50) years; mean body mass index (BMI) 26.60 (24.80, 27.60) kg/m². In this study, 15 postoperative complications occurred (including 5 cases of delayed wound healing, 2 cases of surgical site infection, 5 cases of thromboembolic events, and 3 cases of lateral hinge fracture), all of which were successfully managed. Forty-two knees (24.85%) were classified as having abnormal correction; these knees had significantly higher pre-operative JLCA and post-operative HKA, and significantly lower post-operative HSS scores (P < 0.05). Receiver operating characteristic (ROC) curve analysis identified 3.8° as the optimal cut-off for pre-operative JLCA to predict abnormal correction (AUC = 0.858, 95% CI: 0.799–0.917, sensitivity = 0.857, specificity = 0.724, P < 0.01). Linear regression confirmed that age (P = 0.049) and pre-operative JLCA (P = 0.007) were independent predictors of the post-operative HSS scores. CONCLUSIONS: An increased pre-operative JLCA is a critical determinant of post-operative radiological alignment and clinical prognosis. When pre-operative JLCA ≥ 3.8°, MOWHTO is more likely to result in inaccurate correction, and inferior clinical outcomes. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12891-026-09584-5.