Abstract
The human foot contains a large number of bones, which form joints that can be moved consciously, as well as joints that move only slightly in an unconscious manner. While many studies have investigated the changes in unconsciously moved joints collectively by examining the wide region of the medial longitudinal arch, very few studies have investigated the constituent parts such as the first tarsometatarsal joint (an unconsciously moved joint). Furthermore, the commonly used methods of measurement based on motion capture or fluoroscopy have a problem associated with difficulties in preparing the measuring environment. To measure the dynamic deformation of the first tarsometatarsal joint, which is a part of the medial longitudinal arch, we used flexible polymer curvature sensors that convert the bending curvature to voltage. We attached three of these curvature sensors to measure the deformation of the joint in multiple planes. Twelve healthy adult males (aged 22.6±1.2 years) participated in the experiment, in which they were asked to walk barefoot on a treadmill. The measurements obtained showed dynamic and multi-planar deformation at the first tarsometatarsal joint. We confirmed that the tendency of deformation of the foot structure changes sensitively depending on the state of the foot.
