Wrist ROM measurements using smartphone photography: Reliability and validity

No one has validated measuring the wrist's active range of motion (ROM) using smartphone images in patients. It is not known whether pathological factors affect the accuracy of this measurement technique. The purpose of this study was to assess if smartphone photography is as reliable and valid as manual goniometry for measuring wrist joint ROM. We reviewed 38 wrists in 38 patients (21 women and 17 men) with a mean age of 45 years (range, 26-60). Smartphones were used to take digital photos of injured wrists at extremes of wrist motion, including flexion, extension, radial and ulnar deviation. The mean difference in measured ROM between the two measurement methods (digital photos and handheld goniometer) was compared using Student's t test and the relationship determined using Pearson correlation coefficients. Bland-Altman analysis was used to define the limits of agreement (LOA). No significant difference was found when comparing the wrist ROM in the four positions using manual goniometry and digital measurements from photos taken by a surgeon. Between the goniometer measurements and digital photos taken by a surgeon, the Pearson coefficients were high, with most being above 0.8 for the four positions. The Pearson coefficients also show the smartphone measurements were highly precise. There was high reliability between the photographs taken by surgeons and by patients, as well as high interobserver reliability. Smartphone photography is a reliable and valid method to measure wrist joint ROM in patients. This measurement method can be used to measure outcomes.