Inconsistencies of Foot Type Classification

Abstract

Research background and hypothesis. Literature analysis shows that researchers try to determine which method
used for foot type estimation is the most reliable, and look for correlations between directly received foot measurements
(indexes, angles) ignoring assessment scales. Given different medial longitudinal arch (MLA) assessment scales, the
comparison, discussion and conclusions of the obtained data might be unreliable.
Research aim of this study was to determine the reliability of foot type classification: a) to assess correlation
links between results from various methods used to analyse foot; b) to identify foot type distribution according to
medial longitudinal arch.
Research methods. The MLA of 182 feet was assessed using four prevalent foot type evaluation methods:
the Chipaux-Smirak Index (CSI), the Staheli Index (SI), the Clarke angle (CLA) and arch index by D. S. Williams
(WAI). Pearson’s correlation was used to determine links between foot indexes.
Research results. Very strong link was found between CSI and SI footprint indexes, while medium negative
correlation was determined between Clarke angle with Chipaux-Smirak (CSI) and Staheli (SI) indexes. Average
amount of low arch foot assessed according to the foot type classification scales by the four methods was 64.0  
(SD = 65.5), normal foot 92.25 (SD = 51.77) and high arch foot 25.75 (SD = 35.33).
Discussion and conclusion. Research showed that current foot arch classification was not reliable. The foot type
classification scales presented by F. Forriol, L. T. Staheli, N. M. Clarke and D. S. Williams   define different medial
longitudinal foot arch distribution by testing the same pairs of feet despite the correlative link intensity between foot
arch indexes.

Keywords: footprint, foot arch, assessment scale.