Smartphone “Selfies”—A reliable and accurate tool for measuring elbow range of motion

Abstract

Background To determine if self-taken photographs (“selfies”), performed independently after instruction by video or illustrated handout, would be an accurate and reliable tool for capturing elbow range of motion in patients with elbow contractures. Methods Fifty patients presenting with elbow contractures participated in the study. After completion of the selfie, the senior author clinically measured flexion and extension with a goniometer. The angles from the photographs were measured and analyzed. Results The agreement between goniometer and “selfie” measurements correlated closely (R2 = 0.98) and agreement was excellent in both extension and in flexion with intra-class correlation coefficients of 0.95 (95% CI 0.92 to 0.97) in extension with a mean difference of 2° (95% CI −3° to 7°), and 0.93 (95% CI 0.89 to 0.96) in flexion with a mean difference of 4° (95% CI 0° to 8°). Systematic errors were low in extension, 0° (95% CI, ±11°) and in flexion −3° (95% CI, ±10°). Six patients demonstrated ≥10° difference between clinical and selfie measurements. Ability to take a usable selfie was inversely correlated with age (R2 = 0.97). Discussion Self-taken flexion–extension photographs are a reliable and accurate tool for measuring elbow range of motion. Errors in the selfie technique are well tolerated and appear to have a negligible effect upon measurements of motion. This important parameter of elbow function can therefore be obtained outside a normal clinic visit, thereby improving frequency of follow-up assessments (and minimizing loss to follow-up) necessary for quality control and research.