Evaluation of Prognostic Factors in Medial Open-Wedge High Tibial Osteotomy Using Preoperative Semiquantitative MRI Findings

Abstract

Background: The association between preoperative whole-organ knee magnetic resonance imaging (MRI) findings and 2-year patient-reported outcomes after medial open-wedge high tibial osteotomy (OWHTO) performed for varus medial compartment knee osteoarthritis remains unclear. Purpose/Hypothesis: The purpose of this study was to evaluate associations between preoperative Whole-Organ MRI Score (WORMS) subscores and 2-year outcomes and to test whether trochlear bone marrow lesion (BML) was independently associated with the Symptoms subscale score of the Knee injury and Osteoarthritis Outcome Score (KOOS) at 2 years, after covariate adjustment. It was hypothesized that higher preoperative WORMS values—particularly higher patellofemoral BML subscores—would be associated with less favorable 2-year patient-reported outcomes after OWHTO. Study Design: Case-control study; Level of evidence, 3. Methods: We retrospectively reviewed patients who underwent OWHTO for varus medial compartment knee osteoarthritis between 2018 and 2020 and had preoperative MRI and ≥2-year follow-up. Preoperative modified WORMS subscores including BML were recorded by each compartment. Preoperative versus 2-year clinical (Lysholm score, KOOS) and radiographic outcomes were compared using paired t tests. Spearman correlations assessed associations between WORMS measures and clinical outcomes. KOOS Symptoms at 2 years was prespecified as the primary outcome; multivariable linear regression was performed only for KOOS Symptoms, with trochlear BML WORMS (0-6 points) entered a priori and adjusted for age, body mass index (BMI), and 2-year hip-knee-ankle angle. Results: A total of 44 knees from 36 patients (mean age, 60.1 ± 9.3 years; BMI, 27.7 ± 5.2 kg/m2) were included. Mean Lysholm score and mean KOOS subscales improved significantly at 2 years, and lower-limb alignment parameters changed significantly after OWHTO (P < .05). The WORMS BML subscale showed weak-to-moderate negative correlations with KOOS Symptoms and other KOOS domains. Regional analysis showed that trochlear BML had the most consistent, although modest, associations with 2-year KOOS scores. In the adjusted model, higher trochlear BML was independently associated with lower absolute 2-year KOOS Symptoms scores (β = −7.18 points per 1-point increase; 95% CI, −13.48 to −0.88; P = .03), indicating greater residual symptoms rather than absence of postoperative improvement. Conclusion: Preoperative trochlear BML was associated with lower absolute KOOS Symptoms scores at 2 years after OWHTO, despite significant overall clinical improvement. Trochlear BML may provide adjunctive information for counseling regarding residual symptoms after OWHTO. However, although statistically significant, these correlations were modest in magnitude, with absolute correlation coefficients ranging from 0.30 to 0.48.