[Validity and reliability of spinal clinical measures in ankylosing spondylitis]

To evaluate the validity and the reliability of the main clinical measures of mobility and sagittal spinal curves in ankylosing spondylitis (AS).

Criterion validity of the measure of the distance between C7 spinous process to plumbline (dorsal kyphosis), L3-plumb line (lumbar lordosis), lumbar, dorsolumbar and dorsal mobility. The gold standard was the value obtained from lateral radiological views of the dorsal and lumbar spine in standing position and maximum flexion. The correlation between radiological and clinical measures was assessed by a Spearman correlation coefficient (SCC). The reliability was assessed for all the clinical parameters and for chin-sternum distance (flexion, extension), chin-acromion distance (rotations) and chest expansion using the intraclass correlation coefficient (ICC) and the Bland and Altman method. Were included patients with AS and needing dorsal and lumbar Xrays.

Twenty-two patients (21 men), 32 +/- 11 year old, 51 +/- 10 kg weight, with a mean duration of the disease of 120 +/- 60 months. The ICC values were good or excellent for all parameters except for the measures of dorsal mobility. The validity was evaluated in 18 patients. The value of the SCC between clinical and radiological measures was good except the measures of dorsal kyphosis and dorsal mobility.

The clinical measures of mobility and sagittal curves have metrological properties good enough to be used in the monitoring of AS mainly for the follow-up and the evaluation of the rehabilitation. The measurement of dorsal mobility should be restricted to the lower part only. Although apparently not valid the distance C7-plumbline can be used in management of AS because of its excellent reliability.