Flat foot or flat feet is a condition where one or both feet have little to no arch. As a result, the pads of the feet press into the ground while standing, without a visible arch.
While all babies have flat feet at birth, arches usually form as they grow older and the ligaments and tendons in the feet and leg tighten. Some will grow to have high arches while others have medium or low arches, and some will continue to have flat feet into adulthood.
In some people, arches will develop normally but later collapse. This is known as fallen arches and is often used as another term for flat feet.
There are different types of flat feet:
- Flexible flat feet. This is the most common type, in which the arches are visible when not standing and disappear when standing or when weight is put on the feet. It is more common during childhood or teenage years and gets worse with age as tendons and ligaments in the arches stretch, tear and swell.
- Rigid flat feet. With rigid flat feet, there are no visible arches even when there is no weight on the feet. It may feel painful and be difficult to flex the feet up or down, or side to side. This could be due to abnormal bridges between the bones in the feet.
- Adult-acquired flat feet (fallen arches). In this type of flat feet, the arches collapse or drop unexpectedly, causing the foot to turn outwards. It is most commonly caused by inflammation or a tear in the leg tendon that supports the arch, and can be painful.
- Vertical talus. This is a birth defect that prevents arches from forming, because the talus bone in the ankle is in the wrong position. As a result, the bottom of the foot resembles the curved bottom of a rocking chair, hence it is also called rocker-bottom foot.
For most people, having flat feet is not a cause for concern and does not cause any pain.
However, as the arch helps to distribute body weight, people with flat feet may experience pain or problems with walking, running or standing. This would be caused by the uneven distribution of weight or misalignment, which will show in footwear that wears down more in one area than others.
Many people with flat feet do not experience any problems. For those that do, symptoms may include:
- Leg cramps
- Muscle ache, pain or numbness in the foot, ankle or leg
- Pain in the arch, ankle, heel or outside of the foot, especially after prolonged walking or standing
- Pain while walking
- Changes in the way they walk
- Callosities over the inside of the arch
- Too many toes sign or toe drift (where the front part of the foot and toes point outward)
It is advisable to seek medical advice for severe or sudden symptoms such as difficulty walking, problems with balance, stiff or painful feet or fallen arches (sudden development of flat feet).
Some people have flat feet because it runs in the family (generalised ligamentous laxity). Others develop flat feet later in life. Some factors can increase your risk of flat feet, including:
- Injuries to the Achilles tendon, foot or ankle
- Cerebral palsy
- Down syndrome
- Inflammation (tendonitis) or tearing of the posterior tibial tendon, which is the primary support structure for the foot’s arch
- Muscular dystrophy
Some of the complications and related diseases of flat foot include:
- Bone spurs
- Tendon and ligament problems