A clubfoot is a birth defect. The foot is twisted in (inverted) and down. Without treatment, persons afflicted often appear to walk on their ankles, or on the sides of their feet. It is a common birth defect, occurring in about one in every 1,000 live births. Approximately 50% of cases of clubfoot are bilateral. In most cases it is an isolated dysmelia. Incidence in males is higher than in females.