To investigate whether an exercise program, initially focusing on knee stabilization and subsequently on muscle strength and performance of daily activities is more effective than an exercise program focusing on muscle strength and performance of daily activities only, in reducing activity limitations in patients with knee osteoarthritis (OA) and instability of the knee joint.
A single-blind, randomized, controlled trial involving 159 knee OA patients with self-reported and/or biomechanically assessed knee instability, randomly assigned to two treatment groups. Both groups received a supervised exercise program for 12 weeks, consisting of muscle strengthening exercises and training of daily activities, but only in the experimental group specific knee joint stabilization training was provided. Outcome measures included activity limitations (Western Ontario and McMaster Universities Osteoarthritis Index - WOMAC physical function, primary outcome), pain, global perceived effect and knee stability.
Both treatment groups demonstrated large (∼20-40%) and clinically relevant reductions in activity limitations, pain and knee instability, which were sustained 6 months post-treatment. No differences in effectiveness between experimental and control treatment were found on WOMAC physical function (B (95% confidence interval - CI) = -0.01 (-2.58 to 2.57)) or secondary outcome measures, except for a higher global perceived effect in the experimental group (P = 0.04).
Both exercise programs were highly effective in reducing activity limitations and pain and restoring knee stability in knee OA patients with instability of the knee. In knee OA patients suffering from knee instability, specific knee joint stabilization training, in addition to muscle strengthening and functional exercises, does not seem to have any additional value. Dutch Trial Register (NTR) registration number: NTR1475.