pes planus
A physical defect of the foot characterized by a lowering of the longitudinal arch so that the sole lies flat upon the ground and the foot becomes elongated. The gripping action of the toes is reduced or lost, causing mechanical problems during walking and running, and increasing the risk of overuse injuries (e.g. stress fractures, posterior tibial tendinitis, and compartment syndrome). Shoe inserts (see orthoses) may help an athlete who has flat feet by supporting the inside of the foot.
