A flatfoot in an adult can be the result of a flatfoot that the adult has had since he/she was a child or a new flatfoot deformity that has developed in adulthood. In the former case, the person would have had a flatfoot since a child and only developed symptoms recently. In young adults, this can be as a result of an injury or recent increase in activity. Frequently, young adults with flatfeet have an accessory navicular bone that becomes irritated or symptomatic because of a recent injury or increase in activity. This may in some situations, require removal of the accessory bone for pain relief.
In middle age, as a result of degeneration of the posterior tibial tendon, many people develop a flatfoot that can be painful. The pain can result from a tear or degeneration of the tendon, or due to bony impingement as a result of the foot deformity. If symptoms are mild and the deformity not severe, many can find some relief from orthotics and physiotherapy. When pain persists, relief can be obtained from a tendon reconstruction usually in combination with correction of the flatfoot deformity. Occasionally, if the deformity is severe or arthritis has set in, a formal correction of the foot that involves fusion of the joints is needed.