Dynamic postural balance in ankylosing spondylitis patients.

OBJECTIVES In this study, our objectives were to investigate whether patients with ankylosing spondylitis (AS) have a poorer dynamic balance than normal subjects, and to study the relationship between balance and posture. METHODS Seventy patients (57 men, 13 women) with AS and 35 (31 men, 4 women) controls matched for age, weight, height and body mass index were tested using the Biodex Stability System. Anteroposterior (AP), mediolateral (ML) and overall (OA) indices were obtained with bilateral stance at platform stabilities of 8 and 4. Subjects were tested with 'eyes open' at all times. Correlation analyses were performed between stability indices (OA, AP, ML) and disease duration, cervical rotation (CR), tragus to wall distance (TWD), lumbar side flexion (LSF), lumbar flexion (LF), intermalleolar distance (IMD) and Bath Ankylosing Spondylitis Metrology Index (BASMI) total score. RESULTS No significant difference was found between the AS patients and healthy subjects with respect to all three stability indices at levels 4 and 8. A positive correlation was found only between ML stability index and TWD at level 8 (r, 0.249; P = 0.038). No other positive correlation was detected between stability indices and CR, TWD, LSF, LF, IMD, total BASMI score and disease duration. CONCLUSIONS AS has no negative effect on postural stability. The only clinically significant association was found between dynamic postural balance and TWD.