Concurrent Validity and Reliability of a New Smartphone Application for Measuring Cervical Range of Motion in Healthy Individuals.

Background: Range of motion (ROM) measurement is an important part of physical therapy assessment and patient progress. Smartphones are user-friendly instruments and if proven to be reliable and valid, clinicians can use them for a variety of tasks including ROM measurement.

Objectives: To determine concurrent validity and intra- and inter-rater reliability of the PhysioMaster application in measuring cervical ROM in both Android and iOS operating systems.

Methods: Forty-five healthy individuals (age 31.75 ± 11.94 yrs; 18 men, 27 women) completed this study. Two raters measured cervical ROM, three times each, using an Android phone for intra-rater and inter-rater reliability. With an interval time of 1-7 days after the first session, measurements were repeated by one of the raters once to measure intersession reliability. Validity was estimated by one of the raters using iPhone and Android phones one at a time while 3D motion analysis (3DMA) recorded cervical movements simultaneously. For reliability, intraclass correlation coefficient (ICC), and for validity, Pearson correlation coefficient and Bland-Altman plots were used.

Results: ICC values of ≥0.76 and ≥0.84 demonstrated excellent intra-rater and inter-rater reliability, respectively. For concurrent validity, correlation between each phone and 3DMA was nearly perfect for all movements (0.93 ≤ r ≤ 0.97).

Conclusion: PhysioMaster appears to be a valid and reliable application for measuring cervical ROM in healthy individuals.