Risk factors and preventive strategy for excessive coronal inclination of tibial plateau following medial opening-wedge high tibial osteotomy

Purpose: To investigate risk factors and suggest preventive strategy for excessive coronal inclination of tibial plateau following medial opening-wedge high tibial osteotomy (MOWHTO). Methods: A total of 133 consecutive patients who underwent MOWHTO were retrospectively enrolled. Patients were divided into two groups based on postoperative medial proximal tibial angle (post-MPTA) of 95°: control group (n = 111, 83.5%) with post-MPTA less than 95° and excessive MPTA group (n = 22, 16.5%) with post-MPTA 95° or more. Demographics, radiographic parameters [mechanical lateral distal femoral angle (mLDFA), MPTA, posterior tibial slope, joint line obliquity (JLO), hip-knee-ankle angle, joint line convergence angle (JLCA), weight bearing line ratio, and correction angle], and clinical outcomes of patients were compared. Multiple logistic regression analysis was performed to determine risk factors for post-MPTA 95° or more. Results: Multiple logistic regression analysis showed that preoperative JLO ≥ 3° [odds ratio (OR) 6.940, 95% confidence interval (CI) 2.373–20.296, p < 0.001] and preoperative JLCA ≥ 5° (OR 5.723, 95% CI 1.833–17.865, p = 0.008) were statistically significant risk factors for post-MPTA ≥ 95°. Incidences of excessive MPTA following MOWHTO in patients with none, one, and two risk factors preoperatively were 3.7%, 26.7%, and 77.8%, respectively. Conclusion: Preoperative JLO ≥ 3° and JLCA ≥ 5° were two significant risk factors for excessive MPTA following MOWHTO. Thus, surgeon should consider other types of osteotomy if these two risk factors are present together preoperatively in MOWHTO candidates. Level of evidence: Level III.