Radiographic Progression of Patellofemoral Osteoarthritis Is Not Associated With Long-Term Clinical Outcomes After Open-Wedge High Tibial Osteotomy: A 10-Year Minimum Follow-Up.

PURPOSE: To evaluate the radiographic findings of the patellofemoral (PF) joint and the PF-specific clinical outcomes after open-wedge high tibial osteotomy for medial osteoarthritis (OA) in varus knees with a minimum 10-year follow-up. METHODS: Consecutive patients who underwent open-wedge high tibial osteotomy for medial compartment knee OA or osteonecrosis between 2007 and 2014 with ≥10 years of follow-up were retrospectively reviewed. Patients with incomplete radiographic data or missing scores were excluded. Knees were classified into PF OA progression and nonprogression groups according to changes in the Kellgren-Lawrence grade from preoperative to final follow-up. Progression was defined as an increase of at least 1 Kellgren-Lawrence grade. Clinical outcomes were assessed using the Knee Injury and Osteoarthritis Outcome Score-patellofemoral subscale and the Hospital for Special Surgery patella score. Outcomes were compared using Student's t-test or the Mann-Whitney U test. Predictors of PF OA progression were analyzed by multivariate logistic regression. Survival analysis was performed with conversion to knee arthroplasty as the endpoint. RESULTS: A total of 168 knees were included. The mean follow-up period was 12.2 years (range, 10.0-16.9 years). The 10-year survival rate was 91.3%, and no knees required conversion to knee arthroplasty for PF OA. PF OA progression was observed in 55.4% (93/168). There were no significant differences in the Knee Injury and Osteoarthritis Outcome Score-patellofemoral subscale or Hospital for Special Surgery patella score between the groups (Knee Injury and Osteoarthritis Outcome Score-patellofemoral subscale: 68.5 vs 69.8, P = .533; Hospital for Special Surgery patella score: 89.0 vs 91.0, P = .179). Multivariate logistic regression identified correction angle (odds ratio, 1.361; P = .004) and preoperative Kellgren-Lawrence grade of the PF joint (odds ratio, 0.241; P = .002) as independent predictors of PF OA progression. CONCLUSIONS: Although PF OA progressed after open-wedge high tibial osteotomy, it did not adversely affect the long-term clinical outcomes at a mean follow-up of 12.2 years. LEVEL OF EVIDENCE: Level IV, retrospective cohort study.