Differences in and characteristics of four criteria for assessment of flatfoot

Abstract

Footprint analysis is one of the easiest methods for assessing flatfoot. However, there is no unified standard for the evaluation criteria because many experts have proposed various criteria for footprint-based assessment of flatfoot. The purpose of this study was to aid in the selection of appropriate criteria by analyzing actual footprint data using the top four criteria frequently used in English-language original papers for detection of flatfoot, with the aim of determining the differences between these criteria. When each of the four criteria was applied to single footprints from 30 participants each, the percentage judged to have flatfoot was 57% with the Arch index, 7% with the Staheli index, 40% with the Chippaux-Smirak index, and 37% with Clarke’s angle. The Staheli index, the results of which are influenced by the reference population, is useful for studies such as prevalence studies and tracking of foot pattern changes. The Arch index and the Chippaux-Smirak index could be useful as a foot health index for promoting at-home care for flatfoot, and Clarke’s angle could be useful as a first screening tool in the clinical setting. The four criteria investigated here have different detection rates of flatfoot, so the interchangeability of these criteria should be explored as an extension of this research.