European Journal of Pediatrics

, Volume 170, Issue 5, pp 611–617 | Cite as

Footprint analysis of flatfoot in preschool-aged children

  • Kun-Chung Chen
  • Chih-Jung Yeh
  • Jing-Fu Kuo
  • Ching-Lin Hsieh
  • Shun-Fa Yang
  • Chun-Hou WangEmail author
Original Paper


Our aim in this study was to analyze the footprint measurements of flatfoot in a population of preschool-aged children. Three footprint measurements, the Clarke's angle (CA), Chippaux-Smirak index (CSI), and Staheli arch index (AI), were used for comparison with clinical diagnosis. A total of 2,638 static footprints of children aged from 3 to 6 years were recorded. The clinical diagnosis as a gold standard compared with the results of the CA, CSI, and AI and displayed in a receiver operating characteristic (ROC) curve. In order to illustrate the diagnostic accuracy in clinical settings, their likelihood ratios were calculated given their cutoff points, and their pretest/posttest probabilities were plotted as the Fagan nomogram. The optimal cutoff points for CA, CSI, and AI were 14.04°, 62.70%, and 107.42%, respectively, and all of them showed high sensitivity. The areas under curves were 0.91, 0.95, and 0.92, respectively. The positive predictive values were 0.84, 0.91, and 0.85, and the negative predictive values were 0.82, 0.85, and 0.85, respectively. The positive likelihood ratio values for CA, CSI, and AI were 4.09, 7.52, and 4.61, and the negative likelihood ratio values were 0.18, 0.14, and 0.13, respectively. In conclusion, this study demonstrated that footprint analysis methods are suitable for diagnosing flatfoot in preschool-aged children, and that the most appropriate cutoffs are as follows: CA ≤ 14.04°, CSI > 62.70%, and AI > 107.42%. The CSI had a predictive probability of more than 90% and is recommended in screening for flatfoot in preschool-aged children.


Flatfoot Footprint Preschool-aged children ROC curve 



Clarke's angle


Chippaux-Smirak index


Staheli arch index


medial longitudinal arch


body mass index


receiver operating characteristic


area under the curve


false-positive rate


true-positive rate


positive predictive value


negative predictive value


likelihood ratios


positive likelihood ratio


negative likelihood ratio


confidence interval



The authors thank all participants in this study and the physical therapists, Shiao-Wen Liu, Shiou-Han Yang, and Pei-Shan Tsai, who kindly provided assistance with data collection. This study was supported by research grants from the National Science Council, Taiwan (NSC99-2314-B-040-004-MY3).

Financial disclosure statement

No party having a direct interest in the results of the research supporting this article has or will confer a benefit on us or on any organization with which we are associated.

Conflict of interest statement

All authors state that they do not keep any commercial, financial, or personal relationships that may lead to a conflict of interest that could inappropriately influence (bias) their work.


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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Kun-Chung Chen
    • 1
    • 2
  • Chih-Jung Yeh
    • 3
  • Jing-Fu Kuo
    • 2
  • Ching-Lin Hsieh
    • 4
  • Shun-Fa Yang
    • 1
  • Chun-Hou Wang
    • 2
    • 5
    Email author
  1. 1.Institute of MedicineChung Shan Medical UniversityTaichung CityTaiwan
  2. 2.Physical Therapy Room, Chung Shan Medical University HospitalTaichung CityTaiwan
  3. 3.School of Public HealthChung Shan Medical UniversityTaichung CityTaiwan
  4. 4.School of Occupational Therapy, College of MedicineNational Taiwan UniversityTaipeiTaiwan
  5. 5.School of Physical Therapy, College of Medical TechnologyChung Shan Medical UniversityTaichung CityTaiwan

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