Flat feet, also known as over pronation, is a common condition. In infants and toddlers, the longitudinal arch is not developed and flat feet are normal. Most feet are flexible and an arch appears when the person stands on his or her toes. The arch develops in childhood, and by adulthood most people have developed normal arches.
Most flat feet usually do not cause pain or other problems. Children may, however, experience foot, ankle or lower leg pain from flat feet, which should be evaluated.