Reliability and Validity of Shoulder Range of Motion Measurements using a Smartphone Tele-Assessment Solution among Healthy Adults: A Cross- Sectional Study

Abstract

Introduction: Range of motion measurement is essential for clinical shoulder assessment. By utilizing the Protractor application on a smartphone, a healthcare practitioner has the capability to remotely connect to a patient's device and assess their shoulder range of motion in a live, real-time setting.

Objectives: The study aimed to determine the reliability and validity of the protractor mobile application (app) on shoulder flexion and abduction range of motion among healthy adults.

Methods: In a cross-sectional study, fifty subjects were examined; the protractor app was used to measure shoulder flexion and abduction ROM. To assess the reliability of the Protractor app, the intra-class correlation coefficient (ICC), standard error of measurement (SEM), and minimal detectable change (MDC) were used. Pearson’s correlation coefficients (r) were used to evaluate the Protractor application’s validity against the digital inclinometer.  

Results: The protractor app showed high inter-rater reliability, with ICCs for shoulder flexion and abduction of 0.950 and 0.977, respectively. With ICC values of 0.949 for shoulder flexion and 0.968 for shoulder abduction, the protractor app showed high intra-rater (between-session) reliability. The Protractor app demonstrated strong validity in shoulder flexion (r=0.91, ICC=0.947) and abduction (r=0.95, ICC=0.971) compared to the Digital Inclinometer.

Conclusions: The Protractor mobile application has demonstrated reliability and validity in measuring shoulder ROM, allowing for the utilization of app-captured photos for joint ROM assessment. This approach furnishes a convenient and precise tool for evaluating shoulder range of motion.