Validity and Reliability of 2 Goniometric Mobile Apps: Device, Application, and Examiner Factors.

Context: Smartphones are being used in a variety of practice settings to measure joint range of motion (ROM). A number of factors can affect the validity of the measurements generated. However, there are no studies examining smartphone-based goniometer applications focusing on measurement variability and error arising from the electromechanical properties of the device being used.