Abstract
The objectives of this study were first to test the validity of the iPod Touch digital inclinometer against standard goniometry and the gravity inclinometer, and second to evaluate the intrarater and interrater reliability of the iPod Touch digital inclinometer while measuring hip flexion, hip extension, and knee flexion. This study was intended to determine if iPod Touch digital inclinometer applications are as efficient to use when compared to standard goniometry and the gravity inclinometer. It also helped determine the utility of iPod Touch digital inclinometers in a physical therapy setting. This study included 20 healthy subjects who were measured by two testers with all three measurement tools for all three joint ranges of motion. Comparing measurements between different instruments showed high correlations ranging from r = 0.84 to 0.94. lnterrater reliability among joint motion ranged from r = 0. 70 to 0.83 while intrarater reliability among joint motion ranged from r = 0.89 to 0.91. There were low correlations found between instruments when measuring knee flexion ranging from r =.50 to .76. A systematic error was found to be related to measurement with the goniometer. Goniometric measurements of the hip and knee require landmarks to be re-palpated as the joint goes through its range of motion, and this seems to be a significant potential source of measurement enor. The high correlations found in this study suggest that the iPod touch digital inclinometer application, inclinometer, and goniometer are all reliable for measuring hip flexion, hip extension, and knee flexion. The results also show that each of the measuring tools can be used interchangeably and by different testers to measure each motion. However, use of the goniometer requires skill and practice to perform effectively, while the iPod Touch and inclinometer can be used with little training or expertise to accurately measure joint range of motion.