Ankylosing spondylitis starts from sacroilitis and the inflammation gradually spreads throughout the entire spine. Bony ankylosis may occur in the numerous joints around the thorax in late stage. Ankylosing spondylitis leads to limitation of movement of the spine and thorax. Then these can cause alterations in pulmonary function.

So, we undertook this study to evaluate whether limitation of spinal movement and chest expansion affected pulmonary function and to obtain basic information for chest physical therapy.

71 patients with ankylosing spondylitis were evaluated with mobility of the thoracic cage (chest expansion) and mobility of the spine (Modified Schober test, lateral spinal bending), and pulmonary function test (maximal vital capacity, tidal volume, forced vital capacity: FVC, forced expiratory volume at one second: FEV1.0, forced expiratory volume at one second per forced vital capacity, diffusion capacity).

Results
were as follows:

1) There was a significant correlation between the mobility of the thoracic cage and the mobility of the spine (p<0.05).

2) There were significant correlations between pulmonary function (FVC and FEV1.0) and mobilities of the thoracic cage and the spine (p<0.05).

3) There was a significant correlation between tidal volume (VT) and the mobility of the spine (p<0.05), but no significant correlation between thoracic mobility and VT (p≥0.05).

4) There was no significant correlation between the duration of the illness and pulmonary function (p≥0.05).

Therefore spinal mobility and thoracic mobility seem to contribute in improvement of pulmonary function.