Pes Planus – The Causes and Treatment for Flat Feet

Pes planus is a common issue that is easily diagnosed, and one we treat often. It is a condition in which the arch of your foot is lowered or flattened out, which causes excessive pronation of the foot, forefoot abduction, and eversion of the heel, as seen in the video below.

In most people with flat feet, the inside edge of their shoes typically wears down more quickly because their weight is on the inside of their foot. While most patients know what flat feet are, most don’t know what causes it or why we need to treat it because most of the time it is a painless condition.

Pes planus can be inherited or can be caused by the arches not developing during childhood. It can also be acquired over time, caused by conditions such as rheumatoid arthritis, stroke, diabetes, obesity, hypertension, or from simple wear and tear stresses of age that weaken the tendon that runs along inside of ankle and helps support your arch.

Most patients rarely have symptoms, but pes planus could cause pain in the foot because of changes in work environment, injury, sudden weight gain, activities that put excessive stress on the feet (excessive standing, walking, jumping, or running), or footwear with limited support. This pain can be relieved with calf stretching or foot strengthening exercises, over the counter medications, heat therapy or massaging. Flat feet can alter the alignment of the legs and could cause instability, or even ankle, knee, or lower back joint issues.

Treatment for children with flat feet is typically straightforward because their feet are flexible, meaning their foot is mobile but has excessive valgus at the heel and minimal arch height when the child is weight bearing. This is typically able to be corrected with good shoes and foot orthotics to realign the arch and give added stability. However, treatment in adults can be more complicated.

Adult Acquired Flatfoot

Adult acquired flatfoot over time and can be classified into 4 different stages:

  • Stage I: pain along the medial ankle and arch with bilateral symmetrical flatfoot. This can be treated with custom foot orthotics and well-fitting shoes with good support. The purpose of orthotics is to block or limit painful or destructive motion without reducing or restricting normal motion or muscle function. Physical therapy should be used in stage I or early in stage II to strengthen the muscles and tendons that help support your arch.
  • Stage II: divided into 5 sub-stages in which the deformity gets progressively less flexible. The deformity is also no longer symmetrical. Early in stage II, foot orthotics may be able to correct some of the deformity, but as you progress to late stage II, a short ankle foot orthotic (AFO) may better control the foot and ankle. The device should be articulating, allowing normal motion at the ankle, while still supporting the arch and maintaining the ankle in a neutral position. (
  • Stage III: the deformity is now completely rigid with a flat foot and valgus at the heel. This deformity needs increased control, so your orthotist may recommend an ankle gauntlet type AFO that is non-articulating. A rocker sole may also be added to your shoe to aid in rollover while you are walking since there is no movement at the ankle.
  • Stage IV: characterized by arthritis and a valgus deformity at the ankle. Typically the best treatment for late stage III or stage IV flat foot is a solid ankle AFO or surgical treatment.

Certain modifications can be made to your orthotics to better support your flat feet.