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What exactly is a Flatfoot? Are there different types? If you do a Google Search on “Flatfeet”, you will be supplied with a staggering number of hits; 40,900,000 to be exact (as of 19 August 09).  Let’s take a look at this foot structure that obviously affects many people. What exactly is a flatfoot? A flatfoot, or Pes Planus, is a term given to a foot that has lost its arch and is flat.  There are two distinct types of flatfeet:

(1) The structural flatfoot – the arch of your foot is always flat.  That is, your foot is flat when you are sitting, standing or walking (See Photo A below). 

Photo A

(2) The flexible flatfoot – the arch of your foot is flat only when weight is put on the entire foot (such as standing with weight on entire foot), but intact when weight is taken off the heels (such as standing with weight only on the toes) (See Photos B below).

Photo B1

Photo B2

Standing, weight on heel, the arch is collapsed.

It’s pretty easy to see if you have a structural flatfoot.  But how do you determine if you have a flexible flatfoot?

Take this Footprint Test:

When you get out of a swimming pool, look at your footprint on the concrete.  The front of the foot (the ball) should join the heel by a strip.  Ideally, this strip should be about ½ the width of the ball of the foot. If your foot is flat, then the strip is the same width as the ball of the foot, creating a footprint that looks like a stretched out pancake. (Hence the expression, “flat as a pancake’) (See Foot Imprint below).   However, when you sit down and take weight off your feet, your foot will have an arch.

Photo C

Foot Imprint made by a flexible flatfoot

The structural flatfoot is like a level foundation of a building.  It is very stable and solid and generally requires no treatment.  In this article, I am going to talk about the flexible flatfoot, which is not stable and so can lead to problems in the body including chronic muscle and joint pain.  

What causes the flexible flatfoot? The flexible flatfoot is not a 'cause' in of itself.  It is merely a symptom of an underlying cause. The most frequent common causes cited in the literature for flexible flatfeet are:  

  • Weakening of the tendons in the foot (e.g., Posterior tibial tendonitis[1], Ehlers-Danlos syndrome[2])
  • Weakening of the muscles in the foot (e.g., Myasthenia Gravis, Muscular Dystropy)
  • Nerve Injures (e.g., Multiple Sclerosis)
  • Injury to the foot

In 2002, another common cause of the flexible flatfoot, previously unknown, was described (Rothbart 2002).  It is an embryological foot structure in which the heel bone is twisted inward (See Photo C below).

Photo D

PreClinical Clubfoot Deformity - an abnormal, inherited foot structure

When weight is applied to this foot structure, gravity forces the heel bone to twist outward until the entire bottom surface of the heel bone rests on the ground.  This outward twist of the heel bone causes the inner arch of the foot to flatten.  This embryological foot structure is termed the PreClinical Clubfoot Deformity. 

  • PreClinical – a precursor or milder form of a condition
  • Clubfoot – A congenital malformation in which the entire foot is structurally twisted inwards
  • Deformity – A misshapen alteration of the natural form


[1] Kulowski J. Tendovaginitis (tenosynovitis): general discussion and report of one case involving the posterior tibial tendon. Missouri State Med Assoc. 1936;33:135-7.

[2] Ehlers-Danlos Syndrome. A connective tissue disorder. Wikipedia

Rothbart BA 2009.  What exactly is a Flatfoot? Are there different types?  Podiatry Review, Vol 66(6):4-6.

Rothbart BA, 2002. Medial Column Foot Systems: An Innovative Tool for Improving Posture. Journal of Bodywork and Movement Therapies (6)1:37-46