Is valgus foot always flat? The longitudinal arch of the foot and hindfoot valgus in 10–12 year-olds

Introduction. Flat foot is still a controversial topic. As of yet, there are no unified definitions of this deformation. Aim. To assess the correlation between the longitudinal arch of the foot and hindfoot valgus in school-age children. Material and methods. A total of 362 pupils, 183 girls aged 10.96 ± 0.78 yrs and 179 boys aged 10.89 ± 0.78 yrs, participated in the study. Their height and weight were measured and their Body Mass Index (BMI) weight status was categorized. The Arch Index (AI) was used to assess the longitudinal arch of the foot. Hindfoot valgus was measured by a goniometer and defined as the angular deviation between the tibial anatomical axis and the calcaneus longitudinal axis. Results. About 1/3 of the participants had hollow feet and about a fifth of them had flat feet. No correlations between the longitudinal arch of the foot and the hindfoot valgus were discovered; however, a correlation between excessive weight and the longitudinal flat foot was revealed. No correlations between BMI and hindfoot malalignment were found. Conclusion. Hindfoot valgus was prevalent in a considerable proportion of boys and girls with the flat, normal and hollow foot. Therapeutic correction of valgus feet should be varied and should depend on the quality of the longitudinal arch of the foot.