A person with flat feet (fallen arches) has low arches or no arches at all.
Most cases don't cause problems and treatment isn't usually needed.
The arch, or instep, is the inside part of the foot that's usually raised off the ground when you stand, while the rest of the foot remains flat on the ground.
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.
Do I have flat feet?
Flat feet are easy to identify while standing or walking. When someone with flat feet stands, their inner foot or arch flattens and their foot may roll over to the inner side. This is known as overpronation.
To see whether your foot overpronates, stand on tiptoes or push your big toe back as far as possible. If the arch of your foot doesn't appear, your foot is likely to overpronate when you walk or run.
It can be difficult to tell whether a child has flat feet because their arches may not fully develop until they're 10 years of age.
Causes of flat feet
Having low or no arches is normal for some people. In these cases, flat feet are 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 known as tarsal coalition and results in the feet being flat and stiff.
Flat feet that develop in later life can be caused by a condition that affects the joints, such as arthritis, or an injury to a muscle, tendon or joint in the foot.
Conditions that affect the nervous system (brain and spinal cord) can also cause the arches to fall. Over time, the muscles gradually become stiffer and weaker and lose their flexibility. Conditions where this can occur include cerebral palsy, spina bifida and muscular dystrophy.
Adult-acquired flat feet often affect women over 40 years of age. It often goes undiagnosed and develops when the tendon that supports the foot arch gradually stretches over time.
It's 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. Obesity, high blood pressure(hypertension) and diabetes are all risk factors.
Recent research has found a link with changes to the tendon in the foot and an increase in a type of protein called proteolytic enzyme. These enzymes can break down some areas of the tendon, weakening it and causing the foot arch to fall. Similar changes are also seen in other conditions, such as Achilles tendonitis.
This could have important implications for treating flat feet because 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 to 15 years away.
Problems caused by flat feet
Flat feet don't usually cause problems, but they can put a strain on your muscles and ligaments (ligaments link 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:
the inside of your ankle
the arch of your foot
the outer side of your foot
the knee, hip or back
Some people with flat feet find that their weight is distributed unevenly, particularly if their foot rolls inwards too much (overpronates). If your foot overpronates, your shoes are likely to wear out quickly. Overpronation can also damage your ankle joint and Achilles tendon (the large tendon at the back of your ankle).
When to see your GP
See your GP if you or your child has flat feet and your:
feet are painful, even when wearing supportive, well-fitting shoes
shoes wear out very quickly
feet appear to be getting flatter
feet are weak, numb or stiff
Your GP may refer you to a podiatrist (foot specialist).
Treating flat feet
Treatment isn't usually needed for flat feet because the condition doesn't usually cause any significant problems.
Aching feet can often be relieved by wearing supportive shoes that fit properly. You may need to wear shoes that are wider than normal.
If your feet overpronate, you may need to wear a special insole (an orthotic) 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.
Stretching your calf and Achilles tendon may also help as a tight Achilles can make your foot overpronate. To stretch your calf and Achilles tendon:
step forwards with your left leg and bend it, with your right leg straight and both feet pointing forwards (see picture)
push your right heel into the ground while keeping your right leg straight; you should feel the stretch at the back of your right leg, below the knee
hold the stretch for 15 to 30 seconds and repeat with the opposite leg
repeat the stretch two to four times on each leg, and repeat the overall exercise three to four times a day
When surgery may be needed
In rare cases, surgery may be needed if a child has flat feet caused by a problem they're born with (a congenital abnormality). The foot may need to be straightened or the bones may need to be separated if they're 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. However, surgery may be recommended if the injury or condition is severely affecting your feet.
Where flat feet are caused by 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 needed to straighten the feet.