Flat feet

What is flat foot, and how common is it?

Flat foot (pes planus) means the arch on the inside of your foot is low or missing, so the sole comes into contact with the ground¹. It can be flexible, where an arch forms when you stand on tiptoe, or rigid, where it doesn't².

In children it's usually a normal stage of development, not a disease³. Flexible flat feet are present in 90% of 1 year olds and up to 20% of adults⁴. Reported rates vary widely with age and how flat foot is measured, so figures from different sources can't be compared directly⁵.

What causes flat foot, and who gets it?

In young children, flat feet are usually part of normal development: their joints and ligaments are more flexible, and they have a soft fat pad under the arch⁴⁶. Other things linked with flat feet include family history, tight muscles or tendons, obesity, and conditions such as Ehlers-Danlos syndrome, cerebral palsy, juvenile arthritis and muscular dystrophy⁶.

In children, flat feet are found more often in boys and in younger children³. Obesity is linked with flat foot that lasts⁷, though it isn't clear that weight itself is the cause⁸.

What does it feel like, and how is it diagnosed?

Flat feet don't always cause symptoms⁶. When they do, you might notice foot pain, pain in your shins or calves, pain or swelling on the inside of your ankle, or uneven wear on your shoes⁹. Aching or tiredness tends to show up during or after activity⁶.

A podiatrist or doctor diagnoses flat foot from your history and an examination of your feet, including the tiptoe test to tell flexible from rigid². For children, gait analysis (looking at how they walk) or imaging is added only where needed⁷, and X-rays aren't routinely used⁵.

What helps first?

If flat feet aren't causing any problems, you don't need to do anything, whether you're an adult or a child¹⁰. Flexible flat feet in children are normal and don't routinely need treatment⁴.

If they're sore, options include more supportive shoes, insoles or orthotics (shoe inserts), physiotherapy and weight management⁶. Insoles can improve foot shape and the way pressure moves through the foot in people with flexible flat foot, though how much they ease pain isn't clear yet¹¹. Exercise may also help, but results are mixed; programmes longer than 6 weeks seem more likely to improve arch measurements¹². Use arch supports if a podiatrist advises them⁹.

What helps if that isn't enough?

If symptoms aren't settling, a podiatrist or GP can advise on seeing a foot and ankle (orthopaedic) team. In children, a rigid flat foot, significant pain, or ongoing symptoms despite arch supports are reasons for orthopaedic assessment⁴. In adults, assessment is suggested for a very painful or rigid flat foot, pain at rest or at night, trouble with daily activities, or a mildly sore, flexible flat foot that hasn't improved after more than 6 months of non-surgical care¹³. Exact referral steps vary, so ask your podiatrist or GP.

Which treatment, including surgery, suits which person isn't clear yet. Ask about the benefits and risks before you decide.

How long does it take, and can I stop it coming back?

The outlook in children is generally good. Over 95 percent of children aged 1–5 years grow out of flat feet and develop a normal arch¹⁴. Only a minority have flat foot that lasts, and fewer than 2% develop pain⁷.

In adults, flat foot that develops later from a tendon problem on the inside of the ankle (tibialis posterior tendon dysfunction) tends to get worse over time. If it isn't managed, it can cause pain, weakness and a change in foot shape, so early assessment matters¹⁵.

There's no sure way to stop flat feet developing or returning. It's sensible to check your feet often for changes or increased pain, use arch supports only if a podiatrist advises them, and wear supportive shoes if you're pregnant⁹.