2025 ISAKOS Biennial Congress ePoster
Increased early conversion to knee replacement after medial opening wedge high tibial osteotomy for varus alignment without bony deformity
Takaaki Hiranaka, MD, PhD, Sydney, NSW AUSTRALIA
Takeo Tokura, MD, Kobe, Hyogo JAPAN
Ryan M. Degen, MD, FRCSC, London, ON CANADA
Kevin R. Willits, MD, FRCS, London, ON CANADA
Robert Litchfield, MD, FRCSC, London, ON CANADA
Alan Getgood, MD, FRCS(Tr&Orth), DipSEM, Doha QATAR
Fowler Kennedy Sports Medicine Clinic, Western University, London, ON, CANADA
FDA Status Cleared
Summary
Patients with varus alignment and no bony deformity undergoing medial opening wedge high tibial osteotomy have a significantly higher risk of early conversion to knee replacement (9%) compared to those with bony deformities (3%), highlighting the need for careful preoperative assessment and caution in the absence of bony deformities.
ePosters will be available shortly before Congress
Abstract
Purpose
Medial opening wedge high tibial osteotomy (MOWHTO) is commonly used to correct varus alignment, but its effectiveness in patients without bony deformities remains unclear. This study aims to evaluate the early conversion rate to total knee arthroplasty (TKA) after MOWHTO in patients with varus alignment, comparing those with and without bony deformities.
Methods
A total of 271 digital full-leg standing radiographs of patients with varus alignment (defined as mechanical tibiofemoral varus angle [mFTA] ≥ 3°) who underwent MOWHTO were retrospectively analyzed (mean age 51.6 ± 8.4 years, mean follow-up 3.6 ± 0.9 years; range 2 to 5 years). Patients undergoing MOWHTO for full-thickness chondral defects, meniscal deficiencies, or in conjunction with joint restoration procedures were included. Deformity analysis was performed to measure the mFTA, mechanical medial proximal tibial angle (mMPTA), and mechanical lateral distal femoral angle (mLDFA) using an automated software (MediCAD, Germany). An abnormal mMPTA was defined as <85°, and an abnormal mLDFA as >90°. Patients were classified into two groups: those with bony deformity (tibia, femur, or combined tibia and femur) and those without. Conversion rates to TKA and time to conversion were compared between the two groups. Chi-square tests compared conversion rates, and Mann–Whitney U tests analyzed time to conversion. Statistical significance was set at P = 0.05.
Results
The mean mFTA was 7° ± 3° of varus (range 3°–15°). Among the 271 patients, 67% had bony deformity (38% had tibial deformity, 18% had femoral deformity, and 11% had combined deformity), and 33% had no bony deformity. Conversion to TKA occurred in 3% of the tibial deformity group, 0% of the femoral deformity group, 7% of the combined deformity group, and 9% of the non-bony deformity group. The conversion rate was significantly higher in the non-bony deformity group (9%) compared to the bony deformity group (3%) (p=0.036). The mean time to conversion was 2.5 ± 0.5 years in the bony deformity group and 3.2 ± 0.9 years in the non-bony deformity group, with no significant difference between groups.
Conclusion
Patients undergoing MOWHTO for varus alignment without bony deformity have a significantly higher risk of early conversion to TKA compared to those with bony deformity. These findings highlight the importance of preoperative assessment of bony deformity, the lack of which can still result in a satisfactory outcome following MOWHTO. However, patients should be aware of the greater risk of earlier conversion to TKA In these circumstances.