Postural control, muscle function and psychological factors in rheumatoid arthritis. Are there any relations?

The aim of the present study was to relate postural control, as measured on a quantitative test battery as standing balance on an AMTI force platform, to results of muscle function of the lower extremities, aerobic capacity, disease characteristics, attitudes revealing anxiety, and demographic variables in patients with rheumatoid arthritis (RA). A group of 61 patients with RA was investigated. Multiple regression analyses, using both the stepwise and the backward elimination method, were employed for length of sway path in two-leg standing looking straight ahead and blindfolded as dependent variables. The results revealed postural control in two-leg standing looking straight ahead to be highly related to age and sex but also to isokinetic endurance and to anxiety. In the model, 55% of the variance was explained by these variables at a significance level of p = 0.05. Characteristics of the RA disease, such as c-reactive protein and joint-mobility did not play any major role in explaining postural control.