Flexible vs Rigid Flat Foot

Flat foot, also known as pes planus, is a condition that is most commonly defined by a collapse in the medial longitudinal arch of the foot and sagging of the heel valgus. In newborn babies and toddlers, there is a fat pad on the underside of the medial longitudinal arch.

This, together with an intrinsic laxness and poor neuromuscular control, causes a flattening of children’s feet. The fat pad, however, resolves as the child grows older and the arch of the foot is formed between the third and fifth years of life.

Flat foot

There are three types of flatfeet. The first, flexible flatfoot, is universally seen in most children. It affects both feet, but is usually painless and does not cause any disability.

In contrast to the first, the second type is flexible flatfoot with a shortened Achilles tendon. This type of flatfoot is rarely seen in young children. It affects both feet and causes disability as well as pain in some cases.

The third type of flatfoot, rigid flatfoot, is the least common of the three. It is often found in patients who have complications with the tarsal bones of the feet. Approximately 25% of these patients will have disability and pain and in 50% of them both feet are affected.

Medical diagnosis

In order to diagnose the condition, a child’s feet, ankles and joints are carefully examined in varying positions. A child may be asked to dangle their feet in the air while sitting or to stand on tiptoes.

Examination of the ankles may indicate whether or not the Achilles tendon is short. An ankle that does not move much is indicative of a short tendon. In addition to these investigations, radiographic pictures may be taken, especially in cases that present with pain.

Flexible flatfeet can be distinguished from rigid flatfeet based on the behavior of the collapsed arch under different circumstances. In flexible flatfeet, the deformity is only present when the patient applies weight to the foot. When the patient with flexible flatfeet is tiptoeing or has their ankle plantar flexed, the longitudinal arch of the foot reappears.

A varying longitudinal arch is not the case in rigid flatfoot. These patients have arches that remain fixed in a collapsed position when both in non-weight bearing and weight bearing situations.

In further contrast to painless flexible flatfoot, rigid flatfoot is usually associated with inflammatory and/or osseous disorders. These tend to require special medical considerations.


In most children, flexible flatfoot is physiological and asymptomatic. As a result, treatment is not required, especially since children eventually outgrow it by the age of 8 years.

Nonetheless, these children may be monitored clinically for the onset of any symptoms or signs of the condition progressing. Progression or failure of flatfeet to resolve by the child’s eighth birthday may be indicative of an underlying pathology and further assessment is required.

Flat foot treatment

Symptomatic flexible flatfeet can be treated by a variety of means, including orthoses, appropriate shoes, heel stretch exercises and nonsteroidal anti-inflammatory drugs in more severe cases.

Patients with rigid flatfoot may require surgical procedures with the goals of realigning the foot and the resolution or reduction of pain. Surgery is only indicated when conservative methods fail to provide any relief to the child’s symptoms.

Last Updated: Feb 26, 2019

Dr. Damien Jonas Wilson

Written by

Dr. Damien Jonas Wilson

Dr. Damien Jonas Wilson is a medical doctor from St. Martin in the Carribean. He was awarded his Medical Degree (MD) from the University of Zagreb Teaching Hospital. His training in general medicine and surgery compliments his degree in biomolecular engineering (BASc.Eng.) from Utrecht, the Netherlands. During this degree, he completed a dissertation in the field of oncology at the Harvard Medical School/ Massachusetts General Hospital. Dr. Wilson currently works in the UK as a medical practitioner.


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