The reliability of three techniques for measuring foot position.

The reliability of three commonly used techniques for measuring foot position--valgus index, navicular height, and arch height--was evaluated in a study involving 20 healthy subjects. The results demonstrated significant differences (P < .05) between two observers for all three techniques, although there were no significant differences between two visits for the same observer (P < .05). Secondary analysis demonstrated that navicular height yielded the highest degree of intraobserver and interobserver agreement. The results suggest that there is a wide variation in foot position in the general population, and that measurement error may result from difficulties in defining foot position, techniques used, and instrumentation.