Evaluation of repeatability of pressure algometry on the neck muscles for clinical use.

Neck and shoulder pain is a common disorder which is often associated with a low-pressure pain threshold (PPT) of muscle tissues as manifested by hyperalgesia on palpation or the use of a pressure algometer. The objective of the present study was to evaluate the intratester repeatability of pressure algometer (Force-Five) on the neck and shoulder area in women with neck pain. The study was cross-sectional with single-group repeated measurements. PPT measurements in 20 women with chronic non-specific neck pain were measured on consecutive days at the levator scapulae, at two points on the trapezius muscles on each side and at the sternum as the only non-muscular site. The intratester repeatability of the PPT measurements was satisfactory or good (Intraclass correlation coefficient (ICC 0.78-0.93). The coefficient of repeatability ranged from 16.8 to 24.4N/cm2 and the coefficient of variation ranged from 10% to 22%, depending on the site tested. Considerable individual variation was observed when consecutive measures were analysed against their mean. On the group level the repeatability of the measurements allows the pressure algometer to be used for research purposes. However, on the individual level, due to the considerable variation found in the PPT results, caution is advised when interpreting the results in clinical practice.