Higher correction leads to more hinge fractures but does not affect short-term outcomes in medial opening wedge high tibial osteotomy in medial compartment osteoarthritis

Objectives: Medial opening wedge high tibial osteotomy (MOW-HTO) is a commonly used procedure for the correction of genu varum deformity in medial compartment osteoarthritis of the knee. In this study, we aim to evaluate whether larger correction angles in MOW-HTO increase the incidence of intraoperative lateral hinge fractures and to determine if these corrections or complications impact short-term functional outcomes. Materials and Methods: This retrospective cohort study analyzed 46 knees (37 patients) with isolated medial compartment osteoarthritis treated with MOW-HTO between 2020 and 2023. Patients were divided into two groups based on the required wedge opening: Group 1 (<10 mm, n = 23) and Group 2 (≥10 mm, n = 23). Surgical technique involved a biplane osteotomy with hinge protection using a 2-mm Kirschner wire, replaced by a 4-mm cannulated cancellous screw if a fracture was suspected. Functional outcomes were measured using the Oxford Knee Score (OKS) at 3, 6, and 12 months postoperatively. Results: The incidence of intraoperative lateral hinge fractures (Takeuchi Type I and II) was significantly higher in Group 2 (43.4%) compared to Group 1 (4.3%; P = 0.0031). Group 2 started with a lower baseline OKS, but at 3 months, both groups showed improvement in OKS with no significant intergroup difference ( P = 0.095). However, at 6 and 12 months, Group 2 demonstrated significantly greater OKS improvement compared to Group 1 ( P < 0.001), potentially reflecting the lower baseline scores and greater magnitude of correction in the high-correction group. Conclusion: Larger corrections in MOW-HTO increase the risk of lateral hinge fractures. However, the clinical outcomes are not affected in the short-term. Proper counseling is needed to address the risks and benefits.