Excellent balance skills despite active and inactive juvenile idiopathic arthritis - Unexpected results of a cross-sectional study

Objective Postural control (PC) is fundamental for human movements. Different factors, such as injuries or diseases, can adversely affect PC. The purpose of this study was to evaluate PC in juvenile idiopathic arthritis (JIA) patients with different disease activity levels in comparison to healthy peers. Methods JIA patients with active and inactive lower limb joints (n=36 each group) were examined. Both groups have been on medication and have had physiotherapy for at least 5 years. For comparison, an age- and gender-matched healthy control group (CG; n=36) participated. PC was measured bipedal on a balance-board (S3-Check, TST, Großhoeflein), with an instable tilting between left and right. The parameters of interest were the best results of Stability Index (STI), Sensorimotor Index (SMI) and Symmetry Index (SYI) out of 4 test trials as well as JIA disease-related variables. Data were analysed with descriptive statistics, comparison of averages, linear regression and correlations (p < 0.05). Results The three groups showed no differences in anthropometric characteristics and SYI (p > 0.05). In both JIA groups, STI and SMI were lower than indices of CG (p < 0.05), indicating better stability and motor control. Balance indices did not differ between active and inactive JIA patients (p > 0.05). Conclusion JIA patients showed better PC than CG. Possible explanations are an increased body-awareness due to long-term physiotherapy and daily coordination training due to compensatory movements. The positive results highlight the success of individual, interdisciplinary treatment in JIA and can be used to promote recommendations for safe sport participation.