Improved Coronal Alignment Using the Preemptive Joint Line Convergence Angle Compensation Method in Medial Open Wedge High Tibial Osteotomy: A Retrospective Propensity Score-Matched Analysis

Abstract

Background: Accurate coronal alignment is crucial in medial open wedge high tibial osteotomy (MOWHTO). Postoperative changes in the joint line convergence angle (JLCA) can cause coronal alignment errors. A preemptive JLCA compensation method has been proposed to address this; however, its clinical value remains unclear.Purpose: To assess the accuracy of the preemptive JLCA compensation method for correction angle calculation in MOWHTO.Study Design: Cohort study; Level of evidence, 3.Methods: Patients who underwent MOWHTO for varus osteoarthritis alignment between 2010 and 2024 were reviewed. The patients were classified into 2 groups based on whether the preemptive JLCA compensation method was applied (group 1: the conventional Miniaci method, group 2: the preemptive JLCA compensation method). After propensity score matching for sex, body mass index, hip-knee-ankle (HKA) angle, Kellgren-Lawrence grade, and correction angle on standing radiography, we conducted a comparative analysis of radiologic outcomes (weightbearing ratio) and functional outcomes (Lysholm score and International Knee Documentation Committee [IKDC] scores). Acceptable alignment was defined as a postoperative weightbearing line ratio between 55% and 70%.Results: After propensity score matching, 20 patients were included in each group. The mean preoperative HKA angle was varus 6.2 degrees +/- 2.2 degrees and 6.3 degrees +/- 2.2 degrees (P = .922), while the correction angle measured by the Miniaci method was 10.0 degrees +/- 2.1 degrees and 10.3 degrees +/- 1.7 degrees for the conventional and preemptive JLCA compensation method group, respectively (P = .855). The mean postoperative weightbearing line ratio at 1 year postoperatively was 64.1 +/- 7.4 and 62.5 +/- 4.7 for the conventional and preemptive JLCA compensation methods, respectively, with no significant difference. However, 95.0% of patients in the JCLA modification group achieved acceptable target alignment, compared with 60.0% (12/20) in the conventional group (P = .014). Despite the significant difference in coronal alignment accuracy, functional outcomes showed no significant difference between the 2 groups.Conclusion: The preemptive JLCA compensation method significantly improved correction accuracy, with 95.0% of patients achieving acceptable target alignment, compared with 60.0% with the conventional Miniaci method, although no significant differences in clinical scores were found in the short-term follow-up period.