3D Foot Shape and Shoe Heel Height

In order to clarify quantitatively the changesin foot shape caused by wearing heeled shoes, the three-dimensional shape of the right foot was measured for 39 female subjects under the following three conditions: 1) standing on a horizontal plane, 2) standing on a base with a surface simulating a shoe with a heel height of 4cm, and 3) standing on a base with a surface simulating a shoe with a heel height of 8cm. The shapes of the foot measured under the different conditions were compared using the shape characteristics of foot cross sections and foot outlines in addition to foot dimensions. Sixteen cross sections were calculated perpendicular to a reference plane defined by metatarsale tibiale, the medial heel point, and the foot axis. The shape characteristics used were a flatness index, the direction of the major principal axis, the maximum height and the maximum breadth for sections which were located between MT and the junction of the foot and leg and have closed outlines, the inclination of the midline for sections which were located around the medial and later malleoli, as well as the overhang of the navicular bone and the posterior flexion angle of the medial axis for the foot outlines. As the height of the shoe's heel increased, the medial and lateral arch lengths and the foot breadth became shorter; sections 1-8 became higher, narrower, rounder, and rotated anti-clockwise in the anterior view; the medial inclination of the heel weakened; the foot outline became less outflared and the overhang of navicular bone became less conspicuous. These changes are related to the supination of the foot. Variations in these characteristics did not diminish in conditions 2 or 3, and individuality remained despite these changes. The relation between the changes in these shape characteristics and the height of the heel was not linear. The possible causes of these changes and their significance for designing shoe lasts are discussed.