Smartphone Based Range of Motion Measurement in Physiotherapy

Range of motion measurement is often performed in physiotherapy. It is important for both initial patient's joint health status evaluation, and later on for tracking progress of a rehabilitation therapy. Standard goniometers are often cumbersome to use and many therapists resort to approximative by eye angle assessment. In this paper, we investigate a modern smartphone application goniometer, based on an inertial measurement unit (IMU). We analyze IMU properties and their influence on angle measurement accuracy. The application is tested in a controlled environment and later on in real-life situations. The same set of measurements is performed by experienced physiotherapist using both the smartphone application and traditional goniometers. Shoulder abduction and elbow pronation and supination were examined. The results obtained clearly show that the smartphone application is comparable in accuracy to traditional ways of measurement. There was no statistically significant difference between the measurements made with traditional instruments and the mobile application. It was shown that for some ROM measurements it was efficient and easy to use and can be considered to be a viable and a better alternative to traditional goniometers.