Pronation and supination are the terms used to describe the natural and necessary movements of the feet. There are periods of both through the normal range of movements that take place during the gait cycle.
In technical terms, pronation occurs at the sub-talar joint and is a combination of dorsiflexion, eversion and adduction. Pronation allows the foot to absorb shock and adapt to the surface it lands on while supination allows the bones of the foot to lock into place, enabling the foot to bear the body’s weight whilst standing, walking or running.
Overpronation is a common problem seen by podiatrists and can cause a number of complications.
The human foot and its mechanics are complex. When this dynamic system malfunctions it sets off a chain of adverse effects that impact on the leg and even on the rest of the body.
When walking or running, a combination of weight and momentum means that forces impacting on the foot can be many times that of body weight.
The majority of injuries presenting to podiatrists are due in large part to incorrect foot positions when standing, walking or running.
The best visual example of an overpronated foot is what is normally called a flat foot. This may in itself not be painful. An overpronated foot places more pressure on the inside of the foot, causing incorrect joint positioning in the knee, hip and opposite shoulder.
Overpronation also causes an imbalance of the muscles in both the upper and lower leg. The inner leg muscles are underdeveloped and used while the outer leg muscles are overused and abused. This disturbs the core balance of the body.
Over a prolonged period of time this increases the risk of developing osteoarthritis of the foot, knee and hip. In young adolescents many of the normal growing pains that occur i.e. pain in the heels, shins and/or knees are aggravated by overpronation. Adolescents are usually very active and growth spurts and/or changes in hormone levels can affect the elasticity of the tendons and ligaments.
Symptoms and causes of overpronation
Signs and symptoms of overpronation are numerous. Foot, knee, hip, lower back and neck pain are common as well as Achilles tendonitis, shin splints, leg and foot fatigue and nocturnal leg cramp.
Overpronation has also been linked to the development of a range of foot deformities including bunions and hammertoes.
Technically, overpronation is caused by abnormal alignment of the bones of the foot. This can be a genetic structural arrangement of the foot bones or ligamentous laxity. A previous history of trauma can also be a cause. Another interesting cause for overpronation is incorrect positioning of a baby in the womb and/or premature birth.
Podiatrists treat overpronation and its subsequent complications by means of an orthotic device. This is basically an arch support which is custom-made to fit each patient, being in a sense a wedge that brings the ground up to meet the foot and stop it collapsing into an incorrect or flat position.
A plaster cast is taken of the patient’s foot in the non-weight bearing/resting position held in the correct anatomical position relative to the rest to the body. From this model of the foot a corrective support is fabricated that can be transferred to various pairs of shoes. This effectively supports the foot and allows it to function normally.
South African Podiatry Association (SAPA)