A 'club foot', also called 'congenital talipes equinovarus' ('CTEV'), is a congenital deformity involving one foot or both. The affected foot looks like it has been rotated internally at the ankle. Without treatment, people with club feet often appear to walk on their ankles or on the sides of their feet. It is a relatively common birth defect, occurring in about one in every 1,000 live births. Approximately half of people with clubfoot have it affect both feet, which is called bilateral symmetry club foot. In most cases it is an isolated dysmelia (disorder of the limbs). It occurs in males twice as frequently as in females. A condition of the same name appears in some animals, particularly horses.