The cuneiforms, navicular and cuboid act as a key stone and the total foot structure resembles a triangular shape splayed anteriorly to the forefoot. During the gait the talus functions as a hinge joint. There are two main arches in the foot structure - TRANSVERSE ARCH located in the forefoot area, supporting the metatarsals; and LONGITUDINAL ARCH running medially rearfoot to forefoot.
There are 2 phalanges in the 1st big toe identified as hallux and three phalanges in toes 2 to 5. To enable proper gait the big toe must be able to dorsiflex every step. Inability to dorsiflex can traumatise the hallux joint.
Uninhibited ankle motion should allow for 20° dorsiflexion (upward motion) and 50° plantarflexion (downward motion) of the foot. The subtalar and transverse tarsal joints combine to provide inversion and eversion movements.
The foot has been described as both "delicate and powerful" as it has the power to withstand great stresses and yet is graceful and delicate enough to contain some of the smallest and most delicate bones in the human body.
There have been many studies worldwide to determine foot types and their nature and our own anecdotal evidence shows that there are 4 basic arch types - the following 4 types exist in an approximate breakdown (percentage of the population):
- 5% Flat Foot - typically no arch contour at all, characterised by well developed muscle in the plantar area of the foot structure.
- 85% Pronated Foot - minimum arch shape, arch collapses due to ligamental laxity and the effects of gravity.
- 1% Normal Foot - appearance of the perfect arch contour.
- 9% High Arched Foot - highly defined footprint with least amount of foot on the ground, population usually a high supinator with minimal shock absorption.
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