Elucidation of The Mechanical Load of Intra-Foot in Flatfoot During Running

Abstract

The purpose of this study was to examine the effects of the differences in foot alignment between normal and flatfoot on the ankle joint and the chopart and lisfranc joint moments during running, and to elucidate the mechanism of running disorders caused by flatfoot. Thirteen male subjects with normal feet and 13 male subjects with flatfoot were included in the study. The foot posture index was used to classify normal foot and flatfoot, and reflective markers were attached to the lower leg and foot based on the Rizzoli foot model. The ankle joint, chopart joint, and lisfranc joint moments were calculated using the marker positions, ground reaction forces, and foot pressure data during running. The results showed no significant difference in running speed between the normal foot and flatfoot. Peak value of lisfranc joint plantar flexion moment was significantly higher in flatfoot subjects than in normal foot（p= 0.03）. There was no significant difference in ankle joint（p = 0.42） and chopart joint moment（p= 0.35）between the groups. The results of this study may provide basic data to explain the mechanism of running disorders caused by flatfoot.