Postural Stability in Patients with Moderate Knee Osteoarthritis: Roles of Visual Feedback and Dynamic Perturbations

Knee osteoarthritis is the most common joint disease and aleading cause of disability in old age. The present study aims to analyze thestability of standing with and without perturbation in patients with moderateknee osteoarthritis.

Twenty-eight people (14 men with knee osteoarthritis and 14 healthyindividuals) were evaluated for postural control in this observational crosssectionalstudy. In standing tests, the effects of disease (osteoarthritis vs.healthy), vision (open vs. closed eyes), and support condition (quiet standing vs.on the unstable plate) on balance were studied.

The results showed that the presence of knee osteoarthritis significantlyreduced the root mean square of hip joint flexion in patients compared to thecontrol group (P= .024). The elimination of vision and reducing the base ofsupport by standing on an unstable plate led to local instability in the joints closeto the perturbation, especially the ankle (p <0.001). The center of pressure dataalso showed that the mean (P=0.034) and variability (P=0.003) of the anteriorposteriorexcursion was significantly higher in patients. Patients with kneeosteoarthritis are more vulnerable to falling on an unstable plate.

The body uses a postural stiffening strategy to prevent fallingforward, especially on an unstable plate, and postural adjusting in the mediolateraldirection. In rehabilitative treatments to prevent falls based on the sensoryre-organization plans, e.g., rocking board, foam standing, game therapy, etc., itmay be more efficient to focus on the distal joint muscles.