Validity and Reliability of Elbow Range of Motion Measurements Using Digital Photographs, Movies, and a Goniometry Smartphone Application

Introduction. Range of motion (ROM) is closely monitored before and after surgery for stiff elbow and during rehabilitation. Measurements in the home environment may be helpful to increase involvement and adherence of the patient. Therefore, our objective is to investigate the validity and inter- and intraobserver reliability of 3 alternative methods to assess the ROM by the patient in a home-based situation, in comparison to the universal goniometer (UG). We hypothesize that all 3 alternative methods will be valid alternatives and show a level of reliability equivalent to UG. Methods. Goniometric measurements of elbow flexion, extension, pronation and supination using photography, movie, and a smartphone application were obtained. The validity of these measurement methods was compared to UG. The interobserver and intraobserver reliability were calculated for all measurement methods. Results. Photography and movie based goniometry of the elbow showed good validity in flexion and extension. The interobserver and intraobserver reliability were found to be good to excellent for photo and movie but moderate to poor for UG and the smartphone application. Conclusions. Photo or movie based goniometry seems to be a useful option for initial and follow-up measurement of the elbow ROM, both in the outpatient clinic and in a home environment. Based on our study, the smartphone application we used is not recommended