Calculation of Staheli’s Plantar Arch Index and Prevalence of Flat Feet: a Study with 100 Children Aged 5-9 Years

INTRODUCTION One of the most commonly discussed topics in orthopaedics, particularly in the pediatric realm, are the static-postural changes of the feet. Reviewing the concepts about human foot evolution, we notice that the lower limb, and particularly the foot, is amongst the most distinctive characteristics of human anatomy. The overwhelming development of human brain cortex, vocal apparatus, and lower limb and foot structure make a triad distinguishing men from other mammalians. Footprints of hominoids already demonstrated the existence of a plantar arch 3.7 million years ago, and, during human evolution, feet and not hands experienced extraordinary changes (1,2). Ilfeld(3), worried about the fact that, regardless of the symptoms, individuals with flat feet are not able to join U.S. Army, makes footprints of the feet with load by painting their plantar regions. The assessment of plantar arch development, by the relationship between arch region width and heel region width obtained on a footprint, is proposed by Engel and Staheli(4). This relationship is greatly reduced up to 4 years old, and the standard deviation through this age group is very high, showing a large variation at the initial foot arch development. The longitudinal arch during childhood shows a wide variation, and, from 4 years old on, this relationship remains at about 0.75 in average (5). Among the many clinical test steps, the study of footprints should be included (6). The incidence of flat feet, as shown by footprints, reduces with age, reaching 4% at 10 years old (7). In Brazil, Volpon(8) presents the results of footprints of 637 individuals between zero and 15 years old. The study reports that plantar arch shows a great deal of development up to the 6th year of life, increasing little after that age. It also reports the stabilization of flat foot incidence at around 2%. The prevalence of flat feet declines with age, being higher in children with ligament laxity and the early shoes wearing impairs longitudinal arch development (9). Human foot is the region most affected by anatomical variations in the entire human body, and one of the most important characteristics presenting the highest level of variability is the medial longitudinal arch, and an arch index provides a quantitative measurement of the plantar arch, which can be compared to other measurements (10). The objective of the present study is to evaluate whether Staheli’s plantar arch index shows a stable behavior or not, and the occurrence of flat feet in children aged 5 9 years old, in our environment. This fact is relevant both for clinical practice and, perhaps, for shoemaking industry for this age group.