Lateral opening wedge distal femoral osteotomy for symptomatic lateral compartment osteoarthritis: Survivorship and predictive factors at mean 10-year follow-up

Abstract

Introduction: Lateral opening wedge distal femoral osteotomy (LOWDFO) is a reliable joint-preserving surgical procedure for isolated lateral compartment knee osteoarthritis (OA) and overload in valgus knees. The aim of this study was to evaluate the long-term survivorship and clinical outcomes of patients undergoing LOWDFO, and to identify the factors associated with conversion to total knee arthroplasty (TKA).

Methods: This was a retrospective study of prospectively collected patients who underwent LOWDFO for isolated lateral osteoarthritis and mechanical overload between 2003 and 2023. Clinical outcomes including the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Veterans RAND-12 (VR-12) Physical and Mental scores, and the International Knee Documentation Committee subjective evaluation form (IKDC) were collected and analyzed. Radiographic parameters included hip-knee-ankle angle (HKA) and lateral distal femoral angle (LDFA). Postoperative complications and further reoperations during the follow-up period were recorded. Survivorship was from conversion to TKA and investigated using Kaplan-Meier curve. Logistic regression was used to identify factors associated with conversion, and p values ​< ​0.05 were considered significant.

Results: A total of 48 patients (56% males, mean age 36.5 ​± ​11.3 years) were included for analysis. The complication rate was 35.4%, and the reoperation rate was 29.2% at a mean 10.1 ​± ​4.9-year follow-up. Removal of metal hardware due to pain and/or discomfort was the main cause of reoperation in 20.8% of the patients. The cumulative rate of conversion to TKA at 5 years was 7.0%, 10 years 15.0% and 15 years 29%. Older age was significantly associated with an odd ratio (OR) of 1.16 (R²_N ​= ​0.31; 95% CI: 1.03 to 1.30). The survival analysis showed that patients >45 years at the time of index surgery had an increased hazard ratio (HR) for conversion to TKA of 5.16 (95% CI: 1.32 to 10.10).

Conclusion: LOWDFO yields a 10-year cumulative survivorship of 85% in young patients with lateral compartment isolated knee OA and overload in valgus knees. Age at the time of index surgery is associated with an increased odds of conversion. Removal of metal hardware can affect one in five patients.

Level of evidence: IV.

Keywords: distal femoral osteotomy; knee alignment; knee osteotomy; total knee arthroplasty.