Introduction

There has been little data on the changes in joint space width (JSW), which could represent cartilage restoration, and factors affecting deterioration of JSW following medial opening-wedge high tibial osteotomy (MOWHTO). The purpose of this study was to evaluate the changes in JSW over time after MOWHTO and identify risk factors for deterioration of JSW using anteroposterior (AP) and Rosenberg views.

Methods

We retrospectively analyzed changes in JSW of 104 MOWHTO patients whose preoperative osteoarthritis (OA) grade was K-L grade 3 or less on AP and Rosenberg views. Serial changes in JSW were assessed from preoperatively to at least 3 years postoperatively. Patients were divided into 2 groups according to JSW change patterns on each of AP and Rosenberg views: group 1 had either unchanged or increased JSW, and group 2 had decreased JSW. Clinical outcomes were compared using Western Ontario and McMaster Universities OA Index (WOMAC) score between groups. Multivariate logistic regression analysis was performed to identify risk factors for deterioration of JSW.

Results

Our study population demonstrated increase in JSW overall by 0.5mm and 0.8mm on AP and Rosenberg views, respectively (p <0.05). Group 1 showed significant improvement based on patient reported outcomes (WOMAC) than group 2 (all p < 0.05). Undercorrection was an independent risk factor for failure to achieve maintained or increased JSW on both AP (OR: 6.274, 95% CI 1.870–21.051, p = 0.003) and Rosenberg (OR: 10.465, 95% CI 2.652–41.305, p = 0.001) views.

Conclusion

JSW increased gradually and continuously on standing AP and Rosenberg views until postoperative 3 years after MOWHTO. Deterioration of JSW following MOWHTO was closely related to the undercorrection, and it affected clinical outcomes.
Level of evidence: Level ?, Case control study
Keywords: High Tibial Osteotomy, Medial Opening Wedge High Tibial Osteotomy, Joint Space Width, Cartilage thickness, Anteroposterior, Flexion, Undercorrection.