An investigation into the reliability of the valgus index and its validity as a clinical measurement

Abstract

The valgus index, originally devised as an aid to diagnosing flat foot in children, is examined to investigate its intra-rater reliability and its validity as a clinical measurement to assist biomechanical analysis of the foot. A system for predicting error in a clinical measurement is also outlined. When applied to the valgus index, results showed 3 measurements will give a degree of error of ±2.0. A guide as to the amount of error to be expected for a given number of recordings, is provided in the form of a table. The valgus index was compared with the relaxed calcaneal stance position but no significant linear relationship could be demonstrated. Further comparison with the relaxed calcaneal stance position showed that the valgus index may have advantages over this method of hindfoot assessment; it appears to be less judgemental and more sensitive.