Flat feet (pes planus) is a condition in which the foot does not have a normal arch when standing.

Causes, incidence, and risk factors: Flat feet are a common condition. In infants and toddlers, they can be normal. Flat feet occur because the tissues holding the joints in the foot together (called tendons and ligaments) can be loose. In infants and babies, the fat in the foot is also a factor. As children grow older, these tissues tighten and form an arch, most often by the time the child is 2 or 3 years old. By adulthood, most people have relatively normal arches. However, in some people this arch may never form.

Ageing, injuries, or illness may harm the tendons and ligaments and cause flat feet to develop in a person who has already formed arches. This type of flat foot may only be on one side. A type of painful flat foot in children may be caused by a condition in which two or more of the bones in the foot grow or fuse together. This condition is called a tarsal coalition.


Symptoms: Most flat feet do not cause pain or other problems. At times, foot pain, ankle pain, or lower leg pain are present (especially in children). They should be evaluated by a health care provider or ones podiatrist.

Adults may notice some symptoms. Their feet may become achy or tired when standing for long periods of time or after playing sports. Flat feet may also lead to heel pain and plantar fasciitis, bunions and hammertoes.

Signs and tests: In people with flat feet, the instep of the foot comes in contact with the ground when they walk or stand causing pain and physical limitations.  If an arch reforms while one is standing on their toes, the flat foot is called flexible or reducible. Treatment is usually conservative consisting of shoe modification, orthotics and therapeutic exercises. If the arch does not form with toe-standing, the flat foot is called a rigid flat foot and other tests may be needed, including:

  • X-rays of the foot

  • CT scan to look at the bones in the foot

  • MRI scan to look at the tendons and ligaments in the foot