Flat feet (also called pes planus 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 children are born with flat feet (congenital). There is a functional relationship between the structure of the arch of the foot and the biomechanics of the lower leg. The arch provides an elastic, springy connection between the forefoot and the hind foot so that a majority of the forces incurred during weight bearing on the foot can be dissipated before the force reaches the long bones of the leg and thigh. In pes planus, the head of the talus bone is displaced medially and distal from the navicular bone. As a result, the Plantar calcaneonavicular ligament (spring ligament) and the tendon of the tibialis posterior muscle are stretched to the extent that the individual with pes planus loses the function of the medial longitudinal arch (MLA). If the MLA is absent or nonfunctional in both the seated and standing positions, the individual has "rigid" flatfoot. If the MLA is present and functional while the individual is sitting or standing up on their toes, but this arch disappears when assuming a foot-flat stance, the individual has "supple" flatfoot. This latter condition is often treated with arch supports. Children Studies have shown flat feet are a common occurrence in children and adolescents. The human arch develops in infancy and early childhood as part of normal muscle, tendon, ligament and bone growth. Flat arches in children usually become high arches as the child progresses through adolescence and into adulthood. Children with flat feet are at a higher risk of developing knee, hip, and back pain. A 2007 randomized controlled trial found no evidence for the efficacy of treatment of flat feet in children either from expensive prescribed orthotics (i.e. shoe inserts) or less expensive over-the-counter orthotics. As a symptom itself, flat feet usually accompany genetic musculoskeletal conditions such as dyspraxia, ligamentous laxity or hypermobility. Diagnosis Since children are unlikely to suspect or identify flat feet on their own, it is important for adult caregivers to check on this themselves. Besides visual inspection of feet and of the treadwear pattern on shoe soles, caregivers should notice when a child's gait is abnormal, or the child seems to be in pain from walking. Children who complain about