Validity and Reliability of iPhone Application in Active Internal Rotation Measurement of Shoulder in Patients with Shoulder Pain

INTRODUCTION: A low-cost alternative that can be used to measure shoulder range of motion (ROM) is the goniometer applications available on the iPhone®(Apple, Cupertino, CA, USA) and various smartphones. The validity and reliability of active internal rotation ROM measurement of shoulder with smartphone in patients with shoulder pain were investigated. METHODS: Eighteen patients with shoulder pain who applied to the physical medicine and rehabilitation, shoulder subspecialty outpatient clinic, and 18 volunteers who had not experienced shoulder pain before enrolled in the study. Shoulder internal rotation ROM measurements were conducted with both standard goniometer and iHandy application separately without seeing each other for each participant by one physiatrist and one physiotherapist. RESULTS: It is observed that the intraclass correlation coefficient values of Observer B, except from goniometric measurements, are >0.99 and consistency is very strong among practitioners. For both goniometer measurement and app measurement, the compatibility between the observers was found to be above 0.92. DISCUSSION AND CONCLUSION: This study shows that it is a reliable and valid method to measure shoulder internal rotation movement with the iPhone application.