Causes of Excessive Pronation of the Foot

Excessive pronation of the foot, also referred to as overpronation, occurs when most of the person's body weight is placed on the inner side of the foot while he's moving or walking. Excessive pronation adds to foot disorders, such as stress fractures, ankle injuries and foot pain. This condition can develop due to factors such as muscle weakness in the foot, age and obesity.

Tibialis Posterior Weakness

• The tibialis posterior muscle extends from the calf in the leg to the toes in the foot. It controls the inversion, or turning inward, of the foot, and the planterflexion, or pointing down, of the foot. Weakness in the tibialis posterior muscle is the main cause of excessive pronation. Since this muscle is responsible for slowing the pronation cycle, when it's weakened, excessive pronation can occur.

Subtalar Eversion

• The subtalar joint is located under the ankle, and allows for rotation, inversion and eversion, or turning outward, of the foot. When this joint is everted, the body's weight is placed on the medial side of the foot. The medial area is located toward the middle of the inner part of the foot. When the subtalar joint is out of alignment, and the eversion is abnormal, pronation will develop.

Old Age

• Excessive pronation is more common to older people due to a greater amount of physical inactivity that leads to weight gain. This disturbs the mechanics of the muscular activity in the foot. Over time this disturbance may lead to excessive pronation of the foot.

Obesity

• Obesity causes excessive pronation because the extra weight can cause subtalar eversion. Eventually, this leads the longitudinal arch to collapse, resulting in excessive pronation. The longitudinal arch is located in the middle of the foot, and is composed of the medial, lateral and transverse arches.