Postural stability and the relationship with enthesitis in ankylosing spondylitis: A cross-sectional study

This study aims to investigate the static and dynamic postural stability in ankylosing spondylitis (AS), and to evaluate their relationships with clinical parameters, postural measurements, and enthesitis. Sixty-four patients with AS (37 males, 27 females; mean age 41.06±8.89 years) and 42 healthy individuals (23 males, 19 females; mean age 38.45±8.46 years) were involved in the study. The static and dynamic postural stability of all participants were assessed using the Biodex Balance System. Patients’ posture was evaluated using chest expansion, tragus-wall distance, and the modified Schober’s test. The disease activity (Bath Ankylosing Spondylitis Disease Activity Index: BASDAI), functional status (Bath Ankylosing Spondylitis Functional Index: BASFI), spinal mobility (Bath Ankylosing Spondylitis Metrology Index: BASMI), enthesitis score (Maastricht Ankylosing Spondylitis Enthesitis Score: MASES), pain (Visual Analogue Scale: VAS), quality of life (Ankylosing Spondylitis Quality of Life: ASQoL) and depression (Beck Depression Inventory: BDI) of all patients were evaluated. Similar demographic data were found in both groups. Significant differences were acquired between the patient and control groups regarding all postural stability tests (p<0.05). The BASDAI, BASMI, BASFI, MASES, VAS pain, modified Schober’s test, ASQoL, and BDI were associated with sway velocity on a firm surface with eyes closed. There was a significant correlation between MASES and all tests of sway velocity. Dynamic postural stability in the sagittal plane and whole tests (except on foam surface eyes closed test) of sway velocity were affected negatively in patients with Achilles enthesitis. Static and dynamic postural stability impairments are seen in AS. Enthesitis significantly impaired static postural stability and increased postural sway.