Pes Planus Flat Feet

Pes Planus

Pes planus is the medical term to denote the condition of flat feet or fallen arches. It comes from Latin: pes = foot and planus = plain, level ground.

Flat feet is a common condition, especially in children; about 20% of adults also exhibit pes planus. It has a diverse etiology and may or may not be symptomatic.


In children, pes planus is a part of the developmental process. The arch of the foot develops after birth; in infants, these undeveloped arches are further masked by the presence of baby fat.

Loose ligaments (fibrous connections between bones) in the foot may also be a cause.

As a child starts walking, the arch of the foot becomes more evident, developing fully by about 4 years of age or a little later. In a few cases, there may be failure of arch development leading to flat feet in adults.

Diseases or conditions leading to flat feet in children:

  • Cerebral palsy
  • Poliomyelitis
  • Fusion of the bones of the hind foot

In adults, pes planus is due either to failure of arch development or due to flattening of an already developed arch, in which case it is referred to as Adult Acquired Flatfoot Deformity (AAFD). Adult acquired flat foot may occur due to any of the following causes:

  • Posterior tibial tendon insufficiency (the most common cause)
  • Tearing of foot ligaments
  • Diabetes
  • Poliomyelitis
  • Fractures
  • Loose ligaments
  • Abnormal bone unions in the hind foot
  • Degenerative diseases (rheumatoid arthritis, osteoarthritis)
  • Pregnancy (increased elastin secretion)

Pes planus may be flexible or rigid. A flexible pes planus is one that shows an arch in the non-weight-bearing position but in the weight-bearing position the arch collapses and the foot appears flat on the ground.

A flexible arch is a result of excessive inward rolling (over pronation) of the feet in the weight-bearing position and can be checked by asking the person to stand on tiptoe, or curl the toes keeping the rest of the foot flat on the ground; this makes the arch visible


Flexible flat arch usually does not cause any trouble. However, rigid flat feet, those devoid of arch shape even in the non-weight-bearing position, often produces symptoms such as foot pain, ankle pain or lower leg pain. These symptoms are especially notable after standing for long periods or after strenuous physical activity such as running, dancing, etc.


Flexible pes planus mostly resolves in children until about 10 years of age. Walking barefoot allows for better arch development in children. In adults, flexible pes planus does not require any intervention if it is bilateral, non-progressive and is without any symptoms.

However, treatment is required for rigid pes planus cases or those with symptoms, or if there is any associated disease such as arthritis or diabetes. In such cases, the management varies according to its cause.

Usual treatment includes:


A heel wedge and an arch support is the usual treatment option. It is always best to consult a podiatrist in order to get the problem properly diagnosed.


Stretching exercises to relieve tension in Achilles tendon help reduce over-pronation of the foot.


Surgery is not only costly but also very time-consuming, and should only be considered when all else fails. Surgical options include:

repairing tendons

fusing joints into the correct position