Reliability of two goniometric methods for measuring active subtalar range of motion.

Abstract

Measuring subtalar joint (STJ) motion is accompanied by complications due to the oblique STJ axis which results in triplanar pronation and supination. We developed a pronator and supinator testing apparatus whose axis was aligned with Inman's STJ axis. The purpose of this study was to assess day-to-day reliability of active STJ range of motion (ROM) measurements and to compare the results with those of a rearfoot goniometer. Active pronation, supination and total STJ ROM measurements were administered to 12 men (mean age: 23.8 years) and 12 women (mean age: 22.3 years) at two separate test sessions. Intraclass correlations (ICC), limits of agreement (LoA) and minimum detectable change (MDC) were calculated. Except for pronation ROM in men, the STJ goniometer revealed substantial (ICC > 0.8) reliability in all conditions. Relative MDCs and LoAs were below 15% and 10%, respectively. Significantly higher total ROM (P< 0.05) was found for women compared to men when using the STJ goniometer. The rearfoot goniometer showed high reliability (ICCs > 0.7) but underestimated STJ ROM in average of 37%. Both goniometric methods showed high day-to-day reliability. However, when using the rearfoot goniometer, researchers have to consider whether the level of underestimation of STJ motion is acceptable in the context of the planned investigation.