Age and spinal mobility in ankylosing spondylitis.

Mobility measurements of spine, chest, hips, and shoulder in 73 adult males with ankylosing spondylitis (AS) were correlated with the duration of disease. Several mobility tests showed a significant correlation with the duration of AS, but after adjustment for age, only rotation of the thoracolumbar spine maintained a highly significant correlation. It is concluded that age has a strong effect on the mobility tests. Rotation of the thoracolumbar spine seems to be a valid measure for AS-specific changes.