Core stability and balance in patients with ankylosing spondylitis.

The main purpose of this study was to compare core stability and balance between ankylosing spondylitis (AS) patients and healthy controls. AS patients diagnosed according to the Modified New York criteria and healthy age- and sex-matched controls were included in the study. Clinical status of AS patients was assessed using Bath AS Disease Activity Index (BASDAI), Bath AS Functional Index (BASFI), Bath AS Spinal Mobility Index (BASMI). For evaluation of core stability, static and dynamic core endurance and hip strength were assessed. Trunk flexor and extensor endurance, lateral side bridge tests for static core endurance; modified sit-up test for dynamic core endurance were used. Hip strength was measured with a hand-held dynamometer. Biodex Balance System was used to assess static and dynamic balance. Bilateral standing static and dynamic postural stability, single leg standing postural stability and limits of stability test results were recorded. 64 AS patients (40 male, 24 female) and 64 healthy controls (39 male, 25 female) were assessed. Static and dynamic core endurance test results, hip abductor strength were significantly higher in control group than AS group (p < 0.05). Static postural stability and left leg postural stability test results were significantly better in control group than AS group (p < 0.05). Overall, forward, backward, and right, limits of stability test results were significantly higher in control group (p < 0.05). The results of our study demonstrate that AS has negative effects on core stability and balance. It would be beneficial to add core stability and balance training to AS patients' rehabilitation program.