The variability of the flatfoot frequency depending on the diagnostic criteria and the method of statistical analysis

Abstract

Background. Flatfoot frequency in children varies from 0.6% to 77.9%. This wide-range data is associated with lack of uniform diagnostic criteria and method of statistical analysis.
 Aim. This study aimed to demonstrate the variability in flatfoot frequency in the same population using different indices of footprint and methods of statistical analysis.
 Material and methods. This study included 317 school-age children. Children with orthopedic and foot pathology were excluded. The main evaluation methods were clinical examination, computer plantography with footprint index calculation (Staheli index, Chippaux–Smirak index, Clarke’s angle, podometric index, arch height index), and statistical analysis (descriptive statistics methods with Kolmogorov–Smirnov and Shapiro–Wilk criteria, data definition according to the law of normal distribution with standard deviation and quartile assessment).
 Results. According to the law of normal distribution (with a double standard deviation), our study demonstrated that the flatfoot frequency using the plantar footprint indices varies from 1.6% to 4.8% in 7–17-year-old children and using the medial footprint indices, from 1.28% to 2.8% in the same age. Quartile assessment method showed a flatfoot frequency of 5.85%–28.33% with plantar foot indices and 5.7%–15.43% with medial footprint indices.
 Conclusion. The different plantographic indices and methods of statistical analysis demonstrated that the frequency of a flattened longitudinal arch of the feet in a population may differ significantly. Thus, the frequency of flatfoot determined on the basis of indices calculated on the medial footprint is 1.7–1.8 times lower than that determined on the plantar footprint. In addition, the frequency of flatfoot is 5.5–5.9 times lower than that determined by the quartile assessment.