Influence of self-reported knee instability on outcomes following education and exercise: a cohort study of 2466 patients with knee osteoarthritis

Objective To study the influence of self-reported knee instability on changes in knee pain and gait speed following patient education and supervised exercise therapy in patients with knee osteoarthritis (OA). Methods We included patients enrolled in Good Life with osteoArthritis in Denmark (GLA:D?), an 8-week education and supervised neuromuscular exercise program. Patients were classified into four groups according to their level of self-reported knee instability (Never; Rarely; Sometimes; Most of the time or all the time). Knee pain intensity was evaluated on a 0-100?mm scale and gait speed from the 4x10 meters fast-paced walk test, at baseline and after the program. Using linear regression, we examined the association between knee instability and the change in pain and gait speed, respectively. Sex, age, BMI, physical activity level, and previous knee surgery were covariates in adjusted models. Results Among 2466 patients with knee OA, mean baseline pain and gait speed varied between 38-59?mm and 1.39-1.56 m/s in patients experiencing no instability and patients experiencing instability most or all the time, respectively. All instability groups improved in pain and gait speed. Compared to the no instability group, patients reporting instability most or all the time experienced larger improvements in pain (4.3?mm (95% CI: 1.2 to 7.5)), while no difference between instability groups was found for gait speed. Conclusion In conclusion, knee OA patients with self-reported instability seem to benefit even more from a patient education and supervised exercise therapy program than OA patients without instability.