Flatfoot diagnosis by a unique bimodal distribution of footprint index in children

Chia Hsieh Chang, Yu Chen Chen, Wen Tien Yang, Pei Chi Ho, Ai Wen Hwang, Chien Hung Chen, Jia Hao Chang, Liang Wey Chang

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Abstract

Background: More than 1000 scientific papers have been devoted to flatfoot issue. However, a bimodal distribution of flatfoot indices in school-aged children has never been discovered. The purposes of this study were to establish a new classification of flatfoot by characteristic in frequency distribution of footprint index and to endue the classification with discrepancy in physical fitness. Methods/Principal Findings: In a longitudinal survey of physical fitness and body structure, weight bearing footprints and 3 physical fitness related tests were measured in 1228 school-aged children. Frequency distribution of initial data was tested by Kolmogorov-Smirnov test for normality and a unique bimodal distribution of footprint index was identified. The frequency distribution of footprint index manifests two distinct modes, flatfoot and non-flatfoot, by deconvolution and bootstrapping procedures. A constant intersection value of 1.0 in Staheli's arch index and 0.6 in Chippaux-Smirak index could distinguish the two modes of children, and the value was constant in different age, sex, and weight status. The performance of the one leg balance was inferior in flatfoot girls (median, 4.0 seconds in flatfoot girls vs. 4.3 seconds in non-flatfoot girls, p50.04, 95% CI 0.404-0.484). Discussion: The natural bimodality lends itself to a flatfoot classification. Bimodality suggests development of the child's foot arch would be a leap from one state to another, rather than a continuous growth as body height and weight. The underlying dynamics of the human foot arch and motor development will trigger research prospects.

Original languageEnglish
Article numbere115808
JournalPloS one
Volume9
Issue number12
DOIs
Publication statusPublished - 2014 Dec 31

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ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General

Cite this

Chang, C. H., Chen, Y. C., Yang, W. T., Ho, P. C., Hwang, A. W., Chen, C. H., Chang, J. H., & Chang, L. W. (2014). Flatfoot diagnosis by a unique bimodal distribution of footprint index in children. PloS one, 9(12), [e115808]. https://doi.org/10.1371/journal.pone.0115808