Flat Feet and Pronation “I have flat feet!”

It’s a cry heard daily by many patients. Today’s blog will look at what causes a flat foot, and find out when it may or may not be a problem.

Pes Planus is a term podiatrists use to describe a foot that has a flattened arch. There are a number of causes for flat feet; many of them are due to some form of genetic predisposition. It may be that the bony alignment in your foot just sits that way. The ligaments within the foot may be more mobile compared to a standard foot, which may cause the foot to collapse. The foot may take on that shape to compensate for other issues, such as a leg-length difference, or to get an increased range of motion from tight calves. There could be a weakness, or rupture, of the tibialis posterior tendon, which is an important tendon for maintaining the arch height. Or there may be an abnormal fusion of bones inside the foot.

A flat foot on its own does not have to be the cause of pain or injury. It is usually the type of movement that a flat foot is predisposed to that can cause trouble.

This movement is called pronation. Pronation is a combination of subtle movements that, when viewed in a three dimensional plane, cause the foot to rotate inward at the joint in the foot below the ankle, known as the subtalar joint.

When walking or running, pronation is important as it provides a method of shock absorption for the body’s force as it comes into contact with the ground. A small amount of pronation is important and healthy, however if the movement is excessive – such as is often seen with flat feet – the force on the supporting structures can be increased to a point where they can have damage inflicted upon them.

When the foot pronates, or rolls in, there is tension placed upon the muscles and tissues in the bottom of the foot, as well as those at the inside (medial) section of the lower leg. The shin bone (tibia) rotates inwardly, which can change the position of the knee joint. Similarly, the thigh bone (femur) also rotates inward. This causes the hip to tilt down forward and inward.

As a result, excessive pronation movement of the foot can contribute to a wide variety of problems, including bunion development, plantar fasciitis, shin splints, tibialis posterior tendinopathy, knee pain, hip pain, and back pain.

Podiatrists treat overpronation by assessing muscular strength and range of motion of all of the joints in the leg and foot. Once the cause is identified, they can prescribe specific exercises, footwear, or orthotics to correct the abnormal movement.