Tibial axis inclination becomes vertical within 1 year after double‐level osteotomy, whereas one‐leg standing stability requires up to 2 years

PURPOSE: To evaluate temporal changes in coronal alignment parameters up to 24 months after double-level osteotomy (DLO), as the postoperative time course of tibial axis inclination (TAI) under one-leg stance and its relationship with standing stability remain unknown. METHODS: Eighty-one knees undergoing DLO for severe varus knee osteoarthritis were prospectively evaluated. Radiographic parameters, including hip-knee-ankle angle (HKA), weight-bearing line (WBL) ratio, knee and ankle joint line obliquity (KJLO, AJLO), femoral axis inclination (FAI) and TAI, were measured preoperatively and at 6, 12 and 24 months in one-leg standing radiographs. To capture functional recovery over time, clinical one-leg standing stability was assessed using the one-leg balancing test (OLBT) at 12 and 24 months postoperatively. RESULTS: TAI and FAI showed significant changes by 6 months, and TAI demonstrated an additional significant change between 6 and 12 months (p < 0.05). HKA and WBL ratio improved significantly at 6 months, with only small changes between 6 and 12 months. KJLO and AJLO stabilised by 12 months. At 1 year, 59% of patients achieved 'good' OLBT performance, increasing to 91% at 2 years. Radiographic parameters stabilised earlier than clinical one-leg standing stability. CONCLUSION: After DLO, TAI became nearly vertical and coronal alignment parameters (KJLO, AJLO) stabilised within 1 year, whereas clinical one-leg standing stability required up to 2 years to recover. These findings indicate a temporal association between radiographic alignment stabilisation and recovery of one-leg standing stability. LEVEL OF EVIDENCE: Level Ⅳ, retrospective cohort study.