Flatfoot can be either congenital or acquired, as described below. Flatfoot refers to any abnormalities or disruptions in the relationships and structures that maintain normal foot bones, ligaments, and internal and external foot muscles, resulting in abnormalities in the medial longitudinal arch, lateral longitudinal arch, and transverse arch of the foot, leading to the collapse or disappearance of the arch of the foot, which causes reduced function and pain in standing and walking, bouncing, and so on. These include congenital factors, such as flat feet that can flex without symptoms, flat feet that can flex with symptoms, and flat feet caused by the vertical talus. It also includes acquired flatfoot, such as traumatic factors, posterior tibial tendon rupture, and traumatic subtalar joint dysfunction. Primary joint lesions, such as those caused by rheumatoid arthritis, excessive obesity, prolonged standing, cerebral palsy, etc.