Flat feet

Flat feet, also called pes planus (Latin: "flat foot") or fallen arches, is a postural deformity in which the arches of the foot collapse, with the entire sole of the foot coming into complete or near-complete contact with the ground. Sometimes flat feet are congenital, but they can also develop in childhood or adulthood. The structure of the arch of the foot has a functional relationship with the biomechanics of the leg. The arches provide an elastic, springy connection between the forefoot and the hind foot, and can normally dissipate the majority of the forces incurred by bearing weight on the foot before they reach the long bones of the leg. In an individual with pes planus, the head of the talus bone is displaced medially and distally from the navicular bone. As a result, the plantar calcaneonavicular ligament (spring ligament) and the tendon of the tibialis posterior muscle are stretched to such an extent that the medial longitudinal arch (MLA) is lost. If the arch is present and functional while the individual is sitting or standing up on their toes, but disappears when assuming a foot-flat stance, the individual has "supple" flatfoot. This condition is often treated with arch supports. If the arch is absent or nonfunctional in both positions, the individual has "rigid" flatfoot.