Relation between the medial axis of the foot outline and 3-D foot shape

Posterior flexion angle (PFA) of the medial axis of foot outline is a useful tool for analysing the morphological variation of the human foot. In order to clarify the relation between PFA and the three-dimensional foot shape, the right foot was measured three-dimensionally for 20 male and 39 female subjects. The foot was taken to consist of a series of cross-sections, and morphological characteristics of these sections as well as PFA and the intensity of medial bulge were used to analyse the foot shape. These morphological characteristics were independent of the foot size and correlated with each other. The results of a principal component analysis indicate that the most important variation in the human foot shape is that contrasting a pronated flat foot and a foot of ‘standard’ type. A ‘standard’ type of foot has well-developed plantar arch and straight medial axis, and actually the majority of people do not have this type of foot. The strategies for improving the fit of the shoe in a general population ...