Reliability assessment of measuring active wrist pronation and supination range of motion with a smartphone

This study aimed to improve clinical examination techniques by determining the reliability of different methods to evaluate forearm movements. Two methods using the iPhone™ 5 and its gyroscope application (alone [I5] or attached to a selfie stick [ISS]) were compared with two conventional measurement devices (a plastic goniometer with a hand-held pencil [HHP] and a bubble goniometer [BG]) to evaluate the active range of movement (AROM) of the wrist during pronation and supination. Two independent groups of subjects took part in this prospective single-center diagnostic study: 20 healthy subjects and 20 patients. The four evaluation methods had high intra-observer consistency after three measurements (intra-class correlation coefficient [ICC] [3, 1] of 0.916 for the HHP; 0.944 for ISS; 0.925 for BG; 0.933 for I5) and excellent inter-observer reliability (ICC [2, k] of 0.926 for HHP; 0.934 for ISS; 0.899 for BG; 0.894 for I5), with an agreement of plus or minus 2°. When these devices are used with rigorous methodology, they are reliable for the goniometric evaluation of AROM of wrist pronation and supination.