Predictors of self-reported knee instability among patients with knee osteoarthritis: results of the Amsterdam osteoarthritis cohort.

The aims of the study were to (i) determine the prevalence and course of self-reported knee instability at 2-year follow-up and (ii) identify factors predictive of retention of self-reported knee instability among patients with established knee osteoarthritis (OA). Among 201 patients from the Amsterdam Osteoarthritis (AMS-OA) cohort, demographic characteristics, self-reported knee instability, muscle strength, proprioception, pain, and physical function were assessed at baseline and at 2 years. Exercise over the past 2 years was assessed by evaluating the medical files. The course of self-reported knee instability was determined in patients reporting instability at baseline. Baseline predictors of self-reported knee instability were determined by uni- and multivariable logistic regression analyses. At baseline, 123 (61 %) patients reported knee instability, and of these, 85 (64 %) patients reported instability 2 years later, while 38 (29 %) reported no instability 2 years later. Poor proprioception and high pain assessed at baseline predicted retention of self-reported knee instability at 2 years among patients with self-reported instability at baseline. Knee instability is highly prevalent among patients with knee osteoarthritis. In patients with self-reported knee instability, the majority retained instability over 2 years. Poor proprioception and high pain predicted retention of self-reported knee instability over time.