Flatfoot (Pes Planus)

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What is flatfoot?

When the entire sole of the foot is in contact or near contact with the ground while standing, it is considered a flat foot. The result is that there is no arch to the foot. Flatfoot is a common disorder that affects 20%-30% of the population. It is a complex deformity, and there are types and stages that vary in degree of symptoms and disability. Flatfeet are also referred to as pes planus, posterior tibial tendon dysfunction, and fallen arches.

What are the different types of flatfoot?

There are two general types of flatfoot; flexible flatfoot and rigid flatfoot. If a person is sitting or standing on their toes and they have an arch that disappears when they stand with the entire foot on the ground they have a flexible flatfoot. If there is no arch, whether sitting or standing, they have a "rigid" or "true" flatfoot.

Flexible flatfoot is sometimes called "pediatric flatfoot" because it is first apparent in childhood. Congenital or rigid "true flatfoot" (talipes planovalgus) is much less common in children. Of note, almost all infants appear to have a flatfoot due to the fat pad on the sole of their feet and that the arch does not develop until 5 or 6 years of age.

When a rigid flatfoot develops in adults, it is called "adult acquired flatfoot" or "posterior tibial tendon dysfunction." This type of flatfoot develops because of the weakening of the tibialis posterior muscle tendon, which is a major supporting structure of the foot arch. It is a condition that leads to flattening of the arch and rolling in of the ankle. It is a progressive deformity with early symptoms of pain and swelling at the inside arch of the foot that progresses to the outside of the foot below the ankle. It eventually may lead to arthritis of the foot and ankle joints.

Flexible flatfoot is usually in both feet where posterior tibial tendon dysfunction or adult acquired flatfoot can occur in one or both feet.

Medically Reviewed by a Doctor on 12/19/2014

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