ItemThere’s an App for That: Reliability of an iPhone App to Assess Upper Extremity Proprioception and Stability(International Olympic Committee World Conference on Injury and Illness Prevention, 2017-03) Lynch, James M.; Smith, Keeley; Patel, Vrund; Luchan, KaylaBackground: The ability to maintain joint stability and motion control of the extremities is important in injury prevention/recovery. Quantitative measurement of proprioception, especially the upper extremity, is difficult. Objective: We investigated the reliability of a custom iPhone app to compile accelerometer data and calculate a path length of movement over 20 seconds. Design: This study used a prospective test-retest design. Subjects completed three trials on each upper extremity (RA and LA) 48 hours apart (MWF). A convenience sample of subjects was used. Results: The mean path length for RA was 2669 with a standard error of 149, with LA being 2774 and 124. The intraclass correlation coefficient was 0.86 for the right arm and 0.74 for the left arm across three trials. Conclusions: The accelerometer in an iPhone 6 is a moderately reliable instrument for assessing motion control stability in the upper extremity. We plan to add additional data filtering to the app and repeat.