Effect of Foot Orthoses in Children With Symptomatic Flexible Flatfoot Based on Ultrasonography of the Ankle Invertor and Evertor Muscles

Abstract

Objective To examine the changes in the cross-sectional area (CSA) ratio of the ankle invertors and evertorsfollowing rigid foot orthosis (RFO) application in children with symptomatic flexible flatfoot and to determine thecorrelation between the degree of change in CSA ratio and pain-severity after RFO application.Methods We included 24 children with symptomatic flexible flatfoot without comorbidities and measured theCSAs of tibialis anterior (TA), tibialis posterior (TP), and peroneus longus (PL) using ultrasonography, restingcalcaneal stance position (RCSP) angle, calcaneal pitch (CP), Meary’s angle, talonavicular coverage angle,and talocalcaneal angle using radiography, and foot function index (FFI) at baseline and 12 months after RFOapplication. We analyzed 48 data by measuring both feet of 24 children. The CSA ratios, the ratio of CSA of eachmuscle to the sum of CSA of TA, TP, and PL, were also compared. Correlations between the degree of change inFFI, each muscle’s CSA ratio, RCSP angle, and radiographic measurements were investigated.Results Following RFO application, significant increase in the PL ratio and CP and significant decrease in theRCSP angle, FFI total, pain, and disability scores were observed. The degree of change in the total score, pain, anddisability score of FFI were significantly correlated with the degree of change in the PL ratio and RCSP angle.Conclusion RFOs applied to children with symptomatic flexible flatfoot might reduce the compensatory activitiesof the ankle invertors, thereby increasing the PL ratio, and pain decreases as the PL ratio increases.