Pes planus is the medical term for flat feet: the arch appears low or absent when you stand. Some adults have no pain or limitation, while others notice aching, fatigue, or changes in how the foot moves. The right next step depends on your symptoms, how the foot behaves, and whether the shape is longstanding or has changed.

In Our Expert Opinion: Flat feet are not automatically a problem. A new change, persistent pain, stiffness, or difficulty with everyday activity deserves an evaluation rather than a diagnosis based on appearance alone.

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What Does Pes Planus Mean?

The foot has several arches that help it adapt to the ground and distribute pressure. The medial longitudinal arch runs along the inside of the foot, from the heel toward the toes. In pes planus, that arch is lower than expected or appears to flatten when weight is placed on the foot. The term describes foot shape; it does not, by itself, explain the cause, severity, or need for treatment.

Some people have had low arches since childhood and move comfortably. Others develop a change in adulthood. A low arch may be visible in one or both feet, and the foot may roll inward more as it accepts weight. A clinician considers the whole picture, including pain, flexibility, strength, walking pattern, and how the shape compares with the other foot.

Medical references describe pes planus as loss or lowering of the medial longitudinal arch. The National Library of Medicine's PubMed overview of pes planus provides a clinical definition, while the American Academy of Physical Medicine and Rehabilitation's discussion of pes planus describes congenital and adult-acquired forms.

How Do Flexible and Rigid Flat Feet Differ?

One important distinction is whether the arch can reappear when the foot is not bearing weight or when the person rises onto the toes. A flexible flatfoot changes shape with position. A rigid flatfoot stays relatively flat and stiff. This distinction can guide evaluation, but it cannot identify the cause on its own.

This comparison is a starting point, not a self-test or diagnosis. Flat feet can have different causes, and a person may have a flexible foot with symptoms or a rigid-looking foot without substantial pain. For background on adult-acquired flatfoot, Cleveland Clinic's flat-feet guide also explains that flat feet can be present in childhood or appear later.

What Can Cause Flat Feet in Adults?

Some adults have a low arch that has been present for years. In other cases, the arch lowers or the foot shape changes over time. A change can relate to the tendons and ligaments that support the arch, the joints or bones of the foot, a prior injury, or an underlying condition. The exact cause is not always clear from symptoms alone.

Adult-acquired flatfoot is a term used for a change that develops after the arch was previously more typical. It may be associated with pain along the inside of the ankle or foot, swelling, or reduced ability to rise onto the toes. However, these signs can have other explanations. A foot and ankle surgeon can assess the location and timing of symptoms and determine whether a more specific diagnosis is needed.

It is useful to note when you first observed the change, whether one or both feet are affected, and what activities make discomfort better or worse. Bring details about old injuries, relevant health conditions, and footwear or inserts you have tried. That history can help distinguish a longstanding painless shape from a newer problem that merits closer attention.

For a clearer picture, keep a brief symptom record for several days if it is safe to do so. Write down where discomfort starts, how long you were standing or walking, whether the surface or shoes made a difference, and how long it took to settle. Note whether the arch looks different at the end of the day or whether only one foot seems to have changed. These observations do not replace an exam, but they can make the conversation more specific and help track whether a treatment plan is working.

What Symptoms Can Pes Planus Cause?

Many people with flat feet have no symptoms. When symptoms occur, they may include:

• Aching or tenderness along the arch, inside of the foot, or around the ankle.

• Foot fatigue after standing, walking, or exercise.

• Stiffness or discomfort with certain movements or surfaces.

• Swelling or soreness in a localized area.

• Changes in shoe wear or a sense that the foot rolls inward.

• Reduced comfort with activities that were previously manageable.

These symptoms are not unique to pes planus. Heel pain, tendon irritation, arthritis, an injury, or other conditions may feel similar. A useful first step is to identify exactly where it hurts and what movement brings it on, rather than assuming that a low arch is the cause. The practice's arch condition information and ankle condition information may help you describe the area of concern before an appointment.

Arrange an evaluation if pain persists, gets worse, interferes with walking or daily routines, or accompanies a visible change in foot shape. A sudden or substantial change, significant swelling, or trouble bearing weight should be assessed promptly. People with diabetes, reduced sensation, or circulation concerns should contact a clinician when a new foot problem appears, even if it is not very painful.

How Is Pes Planus Evaluated?

An evaluation begins with your story: when symptoms started, whether the arch has changed, where discomfort occurs, and how the issue affects work, exercise, or everyday movement. Mention any previous foot or ankle injury, relevant medical conditions, and treatments or inserts you have already tried. If symptoms are limited to a particular activity, explain that too.

The clinician may examine your feet while seated and standing, compare both sides, and observe how you walk. They may check whether the arch changes when the foot is unloaded or when you rise onto your toes. The exam can also include the range of motion, tenderness, swelling, skin condition, strength, and the position of the heel and forefoot. The specific checks depend on your symptoms and history.

It can help to bring the shoes you wear most often and any inserts you have tried. If you have photographs showing a recent change in your arch or swelling, ask whether they would be useful to review. Tell the clinician if pain occurs only after a certain distance or if you have stopped an activity because of it. These details help connect the exam findings to the situations in which you need your feet to work.

At the end of the visit, you can ask what diagnosis is being considered, what signs would call for a follow-up, and how long to try a recommended non-surgical option before judging its effect. If imaging or another test is suggested, ask what question it is meant to answer and how the result could change the plan. It is reasonable to make sure you understand the difference between managing symptoms and treating a specific structural cause.

Imaging is not necessary for every person with flat feet. If the examination suggests a structural issue, injury, arthritis, or another cause that needs clarification, the clinician may consider imaging such as X-rays. Further tests depend on what the exam shows. The goal is not simply to label the arch, but to understand whether a treatable problem is contributing to pain or limiting function.

For information on the care available through the practice, see foot and ankle services. If you are preparing for a first visit, the new-patient information page outlines what to expect.

What Treatment Options May Help Adults?

Treatment is guided by symptoms and the reason for them, not by the appearance of a flat arch alone. Someone without pain or activity limits may need no specific treatment. When symptoms are present, care often begins with practical measures and is adjusted according to the exam and response.

Activity adjustments and supportive footwear

A short-term change in the activities that trigger discomfort may give an irritated area a chance to settle. This does not necessarily mean avoiding all movement. A clinician can help identify reasonable modifications and a gradual return to activity. Shoes that feel stable, fit comfortably, and suit the activity may help some people manage symptoms. Wear patterns or a tight toe box can also be worth discussing.

Think about what you need from footwear in daily life: time spent standing, walking on hard floors, commuting, or taking part in a particular sport. A shoe that works for one setting may not feel comfortable in another. Fit matters as much as the label or appearance, so avoid assuming that a particular style will correct every flat foot. If new shoes or an insert create rubbing, pressure, numbness, or more pain, stop using them and ask for advice rather than trying to force an adjustment.

Stretching or exercise guidance

Depending on the findings, a clinician may recommend specific stretching or strengthening exercises. The choice should reflect what is tight, weak, or irritated; a generic routine is not right for every foot. Stop and seek guidance if an exercise causes sharp pain, increases swelling, or makes symptoms noticeably worse.

When you receive an exercise plan, ask how often to do each movement, whether it should feel like a stretch or effort, and how to modify it if symptoms increase. Progress may be gradual, and the aim is to support comfortable function rather than force the arch into a certain shape. If an exercise is difficult because of balance, strength, or another health concern, mention that so the plan can be adjusted safely.

Orthotics and other supports

Arch supports or orthotics may be considered to improve comfort or support the foot during activity. An over-the-counter insert and a custom device are not interchangeable for every patient, and neither permanently changes the shape of every flat foot. The right choice depends on the diagnosis, fit, intended use, and whether the device actually helps. Ask how long to try it, what signs of benefit to track, and what to do if it causes pressure or pain. Learn more about the practice's foot care and treatment services or ask during an evaluation whether an orthotic assessment is appropriate.

Medication or other clinician-directed care

If pain or inflammation is part of the problem, a clinician may discuss appropriate ways to manage it based on your health history. Do not start or continue a medication solely because a foot is flat; medicines can have risks and may not address the underlying cause. The treatment plan should account for other conditions, current medications, and the specific source of symptoms.

When might surgery be discussed?

Surgery is not a routine response to flat feet or a low arch. It may be discussed only when a specific structural or tendon problem is identified and symptoms remain limiting despite appropriate non-surgical care. The options and recovery depend on the diagnosis, the condition of the joints and soft tissues, overall health, and personal goals. This overview is not a surgical guide; a foot and ankle surgeon can explain whether further treatment is relevant in an individual case and review potential benefits, risks, and alternatives.

In Our Expert Opinion, good care begins with matching the treatment to the person, not treating an image or a foot shape in isolation. For a location or appointment question, visit the office locations page or review appointment information.

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Frequently Asked Questions

Does pes planus always cause pain?

No. Many people with flat feet have no pain and do not need treatment. An evaluation is useful when symptoms persist, limit activity, or accompany a change in foot shape.

Can flexible flat feet become rigid?

Foot flexibility and arch height can vary, and a change in movement or stiffness should be assessed in context. A clinician can compare the feet and evaluate what may be contributing; appearance alone cannot tell whether a condition is progressing.

Can shoes or orthotics cure flat feet?

Supportive shoes or orthotics may help some people feel more comfortable, but they do not reliably change the underlying structure for everyone. Their usefulness depends on the cause of symptoms, fit, and response over time.

When should I seek care for a new change?

Contact a clinician when a new change is painful, worsening, associated with swelling or stiffness, or makes walking difficult. Seek prompt advice for a sudden major change or inability to bear weight. If you have diabetes or reduced sensation, do not rely on pain alone to decide whether a new foot problem needs attention.

Ready to Discuss Your Foot Symptoms?

A foot evaluation can help clarify whether a low arch is simply your natural foot shape or part of a problem that needs care. Share what has changed, what activities are affected, and what you have tried so the next steps can be tailored to you.

Contact The Foot & Ankle Group to discuss an evaluation

With the cause and your goals in view, you and your clinician can decide whether observation, supportive care, or further treatment makes sense.