A person with flat feet has low arches or no arches at all. The arch, or instep, is the inside part of the foot that is usually raised off the ground when you stand, while the rest of the foot remains flat on the ground.
It is also known as fallen arches.
Most people have a noticeable space on the inner part of their foot (the arch). The height of the arch varies from person to person.
Flat feet are easy to identify while standing or walking. When someone with flat feet stands, their inner foot or arch flattens, and the foot may roll over to the inner side (known as over-pronation).
To see whether your foot over-pronates, stand on tiptoe or push your big toe back as far as possible. If the arch of your foot appears, it means that your foot is flexible and normal. If the arch does not appear, your foot is likely to over-pronate when you walk or run.
It can be difficult to tell if a child has flat feet as the arches may not fully develop until the age of 10.
Flat feet do not usually cause problems, but they can put a strain on your muscles and ligaments (the tissue that links two bones together at a joint). This may cause pain in your legs when you walk.
If you have flat feet you may experience pain in any of the following areas:
Some people with flat feet find that their weight is distributed unevenly, particularly if their foot over-pronates. If your foot over-pronates, it is likely that your shoes will wear out quickly. Over-pronation can also damage your ankle joint and Achilles tendon (the large tendon at the back of your ankle).
Having low or no arches is normal for some people. In these cases, flat feet is usually inherited and the feet are fairly flexible.
Occasionally, flat feet can be caused by an abnormality that develops in the womb, such as a problem with a joint, or where two or more bones are fused together. This is also known as tarsal coalition and leads to the feet being flat and stiff.
Flat feet that develops in later life can be the result of a condition that affects the joints, such as arthritis, or an injury to a muscle, tendon or the joints of the foot.
Conditions that affect the nervous system (brain and spinal cord) can also cause the arches to fall. This is because over time, the muscles gradually become stiffer and weaker and lose their flexibility. Conditions where this occurs include cerebral palsy, spina bifida and muscular dystrophy.
Adult-acquired flat feet often affects women who are over 40 years of age. It often goes undiagnosed and develops when the tendon that supports the foot arch gradually stretches over time.
It is not fully understood what causes the tendon to become stretched, but some experts believe that wearing high heels and standing or walking for long periods may play a part. You are more at risk if you are obese, have high blood pressure (hypertension) or diabetes.
Recent research has found a link with changes to this tendon and an increase in a type of protein called protelytic enzyme. These enzymes can break down some areas of the tendon, weakening it and causing the foot arch to fall. Similar changes were also seen in other conditions, such as Achilles tendonitis.
This could have important implications for treating flat feet, as medication that specifically targets these enzymes could provide an alternative to surgery.
However, further research is needed and this type of treatment is thought to be about 10-15 years away.
When to see your doctor
Most cases of flat feet do not cause any problems. However, you should go to see your doctor if you or your child have flat feet and:
Your doctor may refer you to a podiatrist (foot specialist).
Treatment is not usually needed for flat feet because they do not usually cause any significant problems.
If your feet ache, the achiness can usually be relieved by wearing supportive shoes that fit properly. You may need to wear shoes that are wider than normal.
If your feet over-pronate, you may need to wear a special insole (orthotic device) inside your shoes to stop your feet rolling inwards when you walk or run. These will usually need to be made and fitted by a podiatrist.
In rare cases, surgery may be needed where a child has flat feet due to a problem they are born with (a congenital abnormality). The foot may need to be straightened, or the bones may need to be separated if they are fused together.
Painkillers and insoles are the first treatment options for flat feet that are caused by a joint problem, such as arthritis, or a torn tendon. If the injury or condition is severely affecting your feet, surgery may be recommended.
In cases where flat feet are the result of a condition that affects the nervous system, special shoes, insoles, or supportive foot or leg braces may be needed. Again, in severe cases, an operation may be required to straighten your feet.
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.