Poster 118: The Accuracy of a Smartphone App in Measuring Shoulder Range of Motion

Objectives: Measuring shoulder movements, specifically range of motion (ROM) of the shoulder joint is an important clinical parameter related to glenohumeral disorders and for functional evaluation of the shoulder before and after treatment, which may include surgery. Currently shoulder ROM measurements are performed in an office setting by the provider or alternatively may be performed by a physical therapist, traditionally with the use of a goniometer. The purpose of this study was to determine the accuracy of a smartphone-based digital ROM tool in assessing active shoulder ROM, compared to traditional goniometry measured by a physical therapist in an office setting. Methods: A prospective, non-blinded study was conducted at a single institution (University of St. Augustine, Austin< TX). Thirty (30) eligible and consenting participants with normal shoulder ROM were recruited. Each participant self-assessed their active shoulder ROM using the smartphone App. A physical therapist concurrently measured each participant’s active shoulder ROM using a hand-held goniometer. This concurrent data collection was designed for greater efficiency and minimal bias. Forward flexion (FF), abduction (AB) external rotation (ER), internal rotation (IR) and extension (EX) were measured. Agreement between the smartphone App and goniometric measurements, as well as intra-rater reliability (precision) was assessed using intraclass correlation coefficients (ICC) and Limits of Agreement analysis. Each measurement was performed in duplicate to assess precision. Statistical analysis was performed using R (https://www.r-project.org/) Results: Data were analyzed for 60 shoulders (30 right, 30 left) from 30 participants (mean age was 31.4, 92% female.) The inter-rater reliability between the two methods was excellent for all movements, with ICC ranging from 0.9 to 0.96. For all movements except AB, the mean difference in the measurements between PT and App was less than 1.3 degrees, and the difference was within 6 degrees of the mean differences for 80% of the participants. For AB, the mean difference was 2.08, and the difference was within 15 degrees of the mean difference for 80% of the participants. The intra-rater reliability or precision ranged from good to excellent. For all movements except IR, both PT and App showed excellent intra-rater reliability (ICCs > 0.90). For IR, good intra-rater reliability (ICCs >= 0.75) was observed. Conclusions: These data provide evidence that the smartphone App can be a reliable and valid tool for measuring shoulder ROM. Smartphone Apps enable self-assessment of ROM by patients at the convenience of their home and allow for remote monitoring at zero visit cost to the patient.