Temporal changes in ankle alignment after medial opening wedge high tibial osteotomy: a long term study

The effect of medial opening wedge high tibial osteotomy (MOWHTO) in coronal limb alignment is known but it may induce secondary changes in ankle alignment. The long-term temporal behaviour of ankle alignment after MOWHTO remains understudied. This study aims at evaluating the long-term changes in ankle alignment following MOWHTO and whether these changes differ according to the degree of coronal plane correction. This retrospective study included 203 knees undergoing MOWHTO. Ankle joint line orientation (AJLO), tibial plafond inclination (TPI), talar tilt (TT), and lateral distal tibial angle (LDTA) were measured preoperatively, at 6 months, and at final follow-up. Patients were categorized into optimum correction, overcorrection, undercorrection, and loss of correction groups based on hip–knee–ankle alignment. Temporal changes were analysed using paired t-tests, and intergroup comparisons of alignment changes were done using the Kruskal–Wallis test. AJLO and TPI demonstrated significant correction toward neutral or valgus alignment at 6 months (p < 0.001), followed by partial loss of correction at final follow-up (p < 0.001). TT showed significant early postoperative change but remained stable thereafter, while LDTA showed a significant decrease only at final follow-up. Categorical analysis revealed a shift from predominantly varus ankle alignment preoperatively to neutral or valgus alignment at 6 months, with partial return toward varus at final follow-up. No significant differences were observed in the magnitude of AJLO or TPI changes between the groups during follow-up (p > 0.05). MOWHTO results in significant early improvement in ankle alignment, with partial regression observed during long-term follow-up. The relation between knee alignment and ankle changes could not be strongly established statistically. Nevertheless, ankle alignment at final follow-up remains in less varus than preoperative values, suggesting a degree of sustained secondary correction following MOWHTO.