Test-Retest and Intrarater Reliability of Assessing Tibial Rotation Range of Motion by Two Devices

Abstract

Rotational motion at the tibia is important for proper lower extremity function, however, normative values vary, and the motion is seldom assessed. Clinicians are increasingly using smartphones for assessing range of motion. The purpose of the study was to assess the reliability of the embedded iPhone 6 compass app and universal goniometer for measuring tibial rotation range of motion. Secondarily, the purpose was to compare readings for the devices. Both devices demonstrated excellent reliability despite systematic bias between the two devices. Assessing tibial rotation with a goniometer results in greater values of motion when compared to using the smartphone compass app. Some of the differences in normative values may be the device or measurement technique utilized. These results show tibial rotation can be reliably assessed with either a smartphone or goniometer, however, the deviations between the two devices may require a scaling factor to be developed for between-instrument comparisons.