Measurement of Foot Skeletal Movement and Surface Deformation when Walking Using Circular Markers and Mesh Deformation

Abstract

Large deformation of human feet during walking causes difficulty in foot-shoe fitting. We measured the standing foot shape using a 3D digitizer, and recorded movements of 20 small circular markers attached to anatomical landmarks of the foot surface using a motion-capture system. The standing foot shape was then fitted to the marker movements, thereby enabling simultaneous estimation of detailed joint motions and foot-surface deformation during walking. By applying this method to capture foot motions when wearing a transparent sandal, we were able to estimate the foot surface’s dynamic deformation and the motions of principal foot bones. Although the results of ultrasonic measurements show that the markers on the foot surface shifted 6 mm to the direction of the longitudinal axis of the cuneiform bone when raising the heel, we confirmed that this skin displacement does not affect the calculation of joint angles. We measured foot deformation of both a bare foot and a foot with a 50-mm-high heel. Although the joint configuration changes with heel height, we found that the relative motion between the midfoot and forefoot segment during the stance phase, which was caused by the deformation of the longitudinal arch, was similar between barefoot and high-heel walking. In addition, the pattern of highly deformed and little-deformed regions of the foot surface was similar.