Flat Foot (Pes Planus)


About one in four people in the United States has flat feet – “pes planus” in medical terms, and also referred to as fallen arches or pronated feet (when one or both feet roll inward). Simply defined, flatfoot is when the sole of your foot is in full contact with the ground. The bottom of the foot lacks the normal arch.

In most cases, flatfoot does not cause symptoms, nor does it adversely affect the ability to carry on with daily activities. It’s normal for children to have flat feet until about age ten, as the bones and ligaments in the foot slowly form an arch. Flatfoot can persist into adulthood, often without symptoms. But flatfoot causes pain for some people, and can affect the ability to walk, run, climb stairs or engage in sports.

There are four types of flatfoot:

Flexible flatfoot

This appears in childhood. When full weight is placed on the foot, the sole of the foot rests completely on the ground. When weight is taken off the foot, the arch returns. This is the most common type of flatfoot, and in the majority of cases, no long-term consequences or pain follow, even into adulthood.

Treatment options for flexible flatfoot
Most cases are not painful, but for those who experience pain, custom shoe inserts can provide relief. Over-the-counter, non-steroidal anti-inflammatory (NSAIDs) medications reduce pain and inflammation. Changing activities – for example, limiting prolonged walking or standing – is helpful. For those who are overweight, diet and exercise might bring relief.

Flexible flatfoot with a short Achilles tendon

A short Achilles, the tendon that runs down the back of your ankle to connect the calf muscle to the heel bone, causes the heel to lift off the ground earlier than normal during each step. This can develop into a painful condition.

Treatment options for flexible flatfoot with a short Achilles tendon
Surgery to lengthen the tendon can be very helpful in reducing pain.

Rigid flatfoot

This type of flat footedness arises from bone malformations or fusions that prevent the arch from forming during childhood. A dislocated talus bone at the top of the arch can result in rigid flatfoot. This can occur at any stage of life.

Treatment options for rigid flatfoot
Multiple surgeries can help alleviate the pain of rigid flatfoot, depending on its cause. Procedures include bone fusions, reconstruction of the arch, and soft tissue repair.

Adult-acquired flatfoot

This type of flatfoot occurs in adults when the posterior tibial tendon becomes inflamed, overstretched or otherwise injured or damaged. This tendon runs from the calf muscle along the inside of the ankle and foot, ending at the arch. The tendon is crucial to support the arch. Posterior tibial tendon dysfunction, which is the medical name for adult-acquired flatfoot, usually occurs in one foot but can emerge in both. It’s a debilitating condition that worsens unless it’s treated early.

Treatment options for adult-acquired flatfoot
Treatment options depend on how advanced the condition is. In the early stages, rest, foot immobilization, physical therapy and over-the-counter pain medications can be used. If the condition worsens, total immobilization with a foot brace is the next step. Surgery is often the last alternative but one that is quite successful. If the tendon is torn, the ends may be sutured back together. Tendon-lengthening surgery or tendon transfers are two procedures that may be considered. Operating on the bones to restore arch height and heel position may be appropriate, along with soft tissue surgery.


Flexible flatfoot
The ankle(s) usually roll inward while the toes tend to point toward the lateral side of the foot (away from the body’s midline). Most cases are not painful.

Flexible flatfoot with a short Achilles tendon
These cases commonly involve a lack of ankle mobility and sometimes calf pain.

Rigid flatfoot
Depending on the type of inherited bone deformity, the soles of the feet can appear to have a convex shape (compared with a normal concave arch). Other indications of inherited flat foot include pain that starts near the back of the foot and spreads upward to the outer ankle and lower leg.

Adult-acquired flatfoot
Often pain develops on the inside of the foot and ankle, along with swelling or redness. As the condition progresses, the foot turns outward while the ankle rolls inward. More advanced cases result in pain on the outside of the foot below the ankle.


Flexible flat foot and flexible flat foot with a short Achilles tendon
This is usually a congenital (inborn) condition that can diminish in time.

Rigid flatfoot
Rigid flatfoot is also a congenital condition. In cases involving a dislocated talus bone, the bone slips out of place and turns on its side, resulting in arch collapse. This most often is caused by a high-impact injury, such as a falling from a height, a car accident or a sports injury.

Adult-acquired flatfoot
Obesity, diabetes, high blood pressure, rheumatoid arthritis and overuse are contributing factors to adult-acquired flat foot. Injuries to the bone or tendon, or existing joint disease also might result in this condition.

Risk Factors

Flat footedness tends to run in families, which suggests it is an inherited condition, particularly in cases of flexible flatfoot and rigid flatfoot. Flatfoot also has been associated with the metabolic disease rickets. Adult-acquired flatfoot affects women four times as often as men. It also tends to occur in older adults, with the average age being about 60.


A physical examination is the usual first step. The doctor examines your arch and asks you to stand with weight on your foot and then take the weight off your foot. If the arch returns, it’s flexible flatfoot; usually no other test is needed. If you experience pain, your physician or a specialist can recommend lifestyle modifications and over-the-counter medications.

With rigid flatfoot, X-rays and/or computed tomography (CT) scans are used to determine conditions of the surrounding bones and tissues. In suspected cases of adult-acquired flatfoot, magnetic resonance imaging (MRI) or ultrasound might be used to assess the condition of the tendon.


In the majority of cases of flexible flatfoot, no complications emerge. When complications occur, they usually involve foot pain and fatigue. Untreated rigid and adult-acquired flatfoot can lead to severe pain and permanent foot deformity.


If you have flexible flatfoot and experience pain and fatigue, consider changing your activities and the shoes you wear, getting custom shoe inserts and, if you’re overweight, shedding pounds to relieve stress on your arches. However, for rigid flatfoot and adult-acquired flatfoot, it’s best to see an orthopaedist. What at first is only bothersome can lead to severe pain and permanent foot deformity if the condition remains untreated.