Under normal conditions, the arch of the foot flattens some each time the foot strikes the ground, helping absorb the shock of impact. This action is called pronation. Flat feet, or fallen arches, occur when the arch collapses completely, and the entire sole comes into contact with the ground during weight-bearing activities such as standing, walking or running.
Overpronation is the most frequent cause of flat feet. Other causes include a tight Achilles tendon or calf muscle, unequal leg lengths, weakness in the hips, fused foot bones, obesity, age and congenital foot abnormalities. Conditions that cause loose ligaments, such as pregnancy, rheumatoid arthritis and Marfan's Syndrome, can also lead to flat feet. Shin splints, plantar fasciitis, stress fractures, hammertoes and bunions are often a result of flat feet.
Not everyone needs treatment for their flat feet, but if secondary problems such as foot, leg or hip pain or tendonitis are present, treatment options vary depending on the cause. For flat feet caused by overpronation, your podiatrist may recommend orthotics, arch supports or shoes with a motion control design to control the pronation. If tendonitis or muscle stiffness is involved, stretching exercises and physical therapy may be helpful. Flat feet resulting from developmental or congenital abnormalities can benefit from a lower leg brace fitted with arch support; for children, a series of casts to realign foot and leg bones is another option. Surgical options include bone implants, lengthening of the Achilles tendon or a tendon transfer to control pronation.