Posture-cognition interaction during quiet standing in patients with knee osteoarthritis.

The aim of this study was to determine the effects of cognitive task (silent backward counting) on postural control in patients with knee osteoarthritis (OA) (n = 25) as compared with asymptomatic controls (n = 25). Static postural control during quiet standing was assessed under different conditions including: (1) rigid surface-open eyes; (2) rigid surface-closed eyes; (3) foam surface-open eyes; and (4) foam surface-closed eyes. Dependent variables were center of pressure (COP) parameters and cognitive score. The results of this study showed that for most COP parameters, the patients with knee OA had greater postural sway than asymptomatic control subjects. Moreover, while cognitive loading affects postural sway in dual-task compared to single-task conditions, the pattern of change was not different between the two groups. Cognitive loading caused decreased postural sway in both groups. Future studies should select patients with more disability, choose more attention demanding cognitive tasks, and expose the subjects to dynamic balance situations to further explore the effect of cognitive loading on postural performance in this specific patient population.