The Thanks Classification, A New Method For Observing Paediatric Flexible Flatfoot

Abstract

Background: Flatfoot shows the collapse or flattening of the medial longitudinal arch. 90% of emergency visits for foot pain in children are attributed to flatfoot. The diagnosis and classification of flexible flat feet in children is currently usually based on imaging or clinical measurements. Most of the existing classification methods of flexible flat feet in children are limited to single plane classification, without considering the influence of rotation and vision deformity. The aim of this research was to to summarize the classification of paediatric flexible flat foot and provide ideas for the treatment strategy of flat feet in children. Method： foot appearance photos and footscan insole system test data of 126 children with flexible flat feet (252 feet) from May 2022 to October 2022 were collected. foot-scan insole system test were used to detect flatfoot and posterior foot heel valgus angle. Based on foot appearance photographs and foot-scan insole system tests. According to whether the foot arch is flat, whether the forefoot with abduction, whether the posterior foot is eversion, and other factors, the “Thanks” the classification of children's flat foot is described. Type A: footscan insole system test results showed flat foot, posterior foot heel valgus angle less than 5°, and without abduction of the forefoot; Type B: footscan insole system test results showed flat foot, combined with abduction of the forefoot, posterior foot heel valgus angle less than 5°; Type C: footscan insole system tests results showed flat foot, posterior foot heel valgus angle more than 5°, and without abduction of forefoot; Type D: footscan insole system tests results showed flat foot, posterior foot heel valgus angle than 5°, and combine with abduction of forefoot. Three experienced foot and ankle surgeons and three rehabilitation doctors independently observed the appearance photos and footscan insole systemtests data of 126 patients with flexible flat feet, determined the flat foot type according to the “Thanks” classification, and randomly reclassified after 4 weeks interval. Finally, 45 cases were randomly selected for internal validation (2 junior orthopedic surgeons), and the intraclass correlation efficient value was used to assess the reliability. Result:The paediatric flexible flat feet were divided into 4 types according to the “Thanks” classification. The intraobserver and interobserver consistency of the Thanks classification was good (ICC 0.895 for foot and ankle surgeons, 0.918 for rehabilitation physicians; The first ICC of foot and ankle surgeons and rehabilitation doctors was 0.903, and the second ICC was 0.856. ICC of internal inspection is 0.873). Conclsion:The “Thanks” the classification of paediatric flexible flat foot is easily learned and accepted by both surgical and non-surgical physicians. It has a good significance for evaluating the functionality of the paediatric flexible flat foot and guiding the selection of the treatment.