Fig. 3

Digital footprints. Top panel: footprints of three children with different arch heights (a, b, c) as measured by both the CSI and KI with the highest arch to the left (a) and a flatfoot to the right (c). Bottom panel: footprints of two children with similarly developed lateral arches (same CSI values) but distinct shapes to the medial arch (different KI values) (d, e, f). Our findings indicate that for a given CSI, those with a higher KI (to the right) (f) take longer step lengths than those with lower KI (to the left) (d). Bottom right (f): the plantar view of a foot skeleton has been superimposed on the child’s footprint to indicate which bones (talus, navicular, medial cuneiform, and first metatarsal) contribute to the high medial arch