Aim
To describe contemporary knee osteotomy practice in Australia and to determine medium-term conversion rates to total knee replacement (TKR). A secondary aim was to compare conversion risk between valgus-producing tibial osteotomy and medial unicompartmental knee replacement (UKR) in patients aged <55 years with osteoarthritis.
Methods
Australian Orthopaedic Association (AOA) Musculoskeletal Registry data comprising data from the Australian Knee Osteotomy Registry and the AOA National Joint Replacement Registry were analysed from December 2016 to September 2025. Patient demographics, diagnosis, surgical technique, fixation, graft use, coincidental procedures, reoperation, and conversion to knee replacement was recorded. The primary endpoint was time to conversion to primary knee replacement, reported as cumulative percent conversion (CPC) using Kaplan–Meier survivorship methods with 95% confidence intervals (CI). Hazard ratios (HR) adjusted for age and sex were calculated. Reoperation of osteotomy was evaluated as a secondary outcome.
Results
A total of 2,563 knee osteotomy procedures were reported (2,047 tibial, 447 femoral, 69 reoperations), performed by 216 surgeons across 100 hospitals. Mean age was 44.7 ± 10.8 years, and 75.4% were male. Osteoarthritis was the primary diagnosis in 86.4%, with 65% classified as Ahlbäck grade ≤2. Reoperation occurred in 2.7%, most commonly for inadequate correction (49.3%) and delayed union/non-union (27.5%). At eight years, CPC to TKR for valgus-producing tibial osteotomy was 2.1% (95% CI 1.2–3.8). In patients <55 years with osteoarthritis, tibial osteotomy demonstrated lower conversion risk compared with medial UKR (8-year CPC 2.2% vs 7.6%; HR 6.20, 95% CI 3.35–11.49, p<0.001).
Conclusions
Knee osteotomy in Australia is predominantly performed in young, healthy patients with early-to-moderate osteoarthritis and demonstrates encouraging medium-term durability. Valgus-producing tibial osteotomy shows low conversion to TKR and a lower risk of conversion than medial UKR in younger patients. These findings support knee osteotomy as a durable joint-preserving strategy in appropriately selected patients.
