Photo-Based Range-of-Motion Measurement: Reliability and Concurrent Validity in Children With Cerebral Palsy

Purpose: To investigate intrarater and interrater reliability, agreement, and concurrent validity of a smartphone photography-based application compared with a universal goniometer in children with cerebral palsy. Methods: Range of motion of hip abduction, popliteal angle, and ankle dorsiflexion was measured with a universal goniometer and a photography-based application in children with cerebral palsy, Gross Motor Function Classification System levels I to V. A 2-way random-effects intraclass correlation coefficients and Bland-Altman plots, standard error of measurement, and smallest detectable change were used for analyses. Results: The application had good to excellent reliability and concurrent validity compared with a universal goniometer, while the large measurement error of both methods suggests that changes of 10° to 23° are needed to be certain that changes over time are not results of measurement error. Conclusions: A photography-based goniometer can be a reliable and valid tool when measuring range of motion in children with cerebral palsy. Correspondence: Mette Johansen, PT, Msc, Clinic for Anesthesiology, Child Diseases, Circulation and Women, Aalborg University Hospital, Hobrovej 18-22, 9100 Aalborg, Denmark ([email protected]). Grant Support: The project is funded by The Physiotherapy Practice Foundation. Dr Skou is currently funded by the Independent Research Fund Denmark (DFF—6110-00045) and The Lundbeck Foundation. The funders did not have any role in this study other than to provide funding. Dr Skou is associate editor of the Journal of Orthopaedic & Sports Physical Therapy, has received grants from The Lundbeck Foundation, personal fees from Munksgaard, all of which are outside the submitted work. He is cofounder of GLA:D, a not-for-profit initiative hosted at University of Southern Denmark aimed at implementing clinical guidelines for osteoarthritis in clinical practice. The authors affirm that they have no financial affiliation (including research funding) or involvement with any commercial organization that has a direct financial interest in any matter included in this manuscript, except as disclosed cited in the manuscript. Copyright © 2020 Academy of Pediatric Physical Therapy of the American Physical Therapy Association