Reliability of arthrometric measurement of shoulder lateral rotation movement in healthy subjects.

Numerous pathologic conditions of the shoulder result in loss of range of motion with lateral rotation being one of the most affected movements. Therefore, it is essential to know the reliability of the methods to measure this motion from a treatment evaluation perspective. The purpose of this study was to examine the reliability of the shoulder lateral rotation movement measured by an arthrometric method. Fifteen healthy subjects participated in the study. The passive range of motion in lateral rotation of the shoulder was measured with an arthrometric method for three positions of shoulder abduction and with three loads. Two evaluators took each measurement on two separate occasions. The reliability was good at 60 degrees and 90 degrees abduction with dependability indexes (phi) ranging from 0.77 to 0.87 and SEMs lower than 5 degrees. The reliability at 25 degrees abduction was lower with dependability indexes (phi) ranging from 0.52 to 0.66 and SEMs of 7 degrees or 8 degrees. Reliability was highest with the heaviest load reaching 0.66, 0.84, and 0.87 for the 25 degrees, 60 degrees, 90 degrees abduction angles, respectively. In all conditions of measurement, differences between intratester and intertester reliability were minimal. Reliability of the shoulder lateral rotation measured by arthrometry was dependent on angle of abduction and load used to move the shoulder. Further studies are needed to confirm these findings in individuals with impaired shoulders.