Risk Factors for the Progression of Varus Ankle Osteoarthritis

BACKGROUND: With the increase in life expectancy, the prevalence of ankle osteoarthritis (OA) is also expected to increase in the future. Functional disability and diminished quality of life associated with end-stage ankle OA are comparable to those associated with end-stage hip or knee OA. However, there are few reports on the natural history and progression of patients with ankle OA. Hence, this study aimed to evaluate the risk factors for progression in patients with varus ankle OA. METHODS: We evaluated 68 ankles from 58 patients diagnosed with varus ankle OA using radiography performed at intervals over at least 60 months. The mean follow-up period was 99 ± 40 months. Narrowing of the joint space and increasing osteophyte formation were defined as ankle OA progression. Multivariate analysis was performed using logistic regression to predict the odds of progression; the model included 2 clinical variables and 7 radiographic variables. RESULTS: Of the 68 ankles, 39 (57%) progressed. In multivariable logistic regression analyses, patient’s age (odds ratio [OR] 0.92, 95% CI 0.85-0.99, P < .03), and the talar tilt (TT; OR 2.2, 95% CI 1.39-3.42, P = .001) were found to be independent factors for progression. The area under the curve (AUC) of the receiver operating characteristic curve for TT was 0.844, and the cutoff value was 2.0 degrees. CONCLUSION: TT was found to be a primary factor associated with varus ankle OA progression. The risk appeared higher in patients with a TT more than 2.0 degrees. LEVEL OF EVIDENCE: Level III, retrospective case control study.