Inter- and Intra-rater Reliability of Measurement of Range of Motion of the Shoulder Joint Using an iPhone

Abstract

[Purpose] The purpose of this study was to clarify the intra- and inter-rater reliability of an iPhone measurement application. [Participants and Methods] The subjects were 10 male university students, 20 arms, and the intraclass correlation coefficient (ICC) was calculated for those who did and did not use an iPhone for measurement. The range of motion of external and internal rotation of the shoulder joint was measured in the supine position with the shoulder joint in 90 degrees of external rotation, the elbow joint in 90 degrees of external rotation, and the forearm in the middle position. [Results] The intra-rater reliability of shoulder joint external rotation and internal rotation range of motion measurement was ICC (1,1) and (1,2) = 0.9 or higher. The inter-rater reliability of shoulder joint external rotation and internal rotation range of motion measurement was ICC (2,1) and (2,2) = 0.8 or higher. [Conclusion] The iPhone-based shoulder rotation range-of-motion measurement was found to be highly reliable.