Foot types can be divided into three major groups: the flat foot (Pes Planus), the high arched foot (Pes Valgus) and the normal to low arched foot. A true 'flat foot' is very rare. In fact, less than
5% of the population have flat feet i.e. a foot with no arch present whatsoever and the entire bottom surface of the foot being flat on the ground. About 5-10% of people have a high arched foot. The
majority of the population have a normal to low arch. Even though the arches appear to be normal most of us suffer from over-pronation during walking, running and standing, due to the hard, flat
unnatural surfaces we walk on, combined with wearing unsupportive footwear. With every step we take the arches flatten and the ankles roll inwards. Pronation itself is not wrong because we need to
pronate and supinate as part of our natural gait cycle. Pronation (rolling in) acts as a shock-absorbing mechanism and supination (rolling out) helps to propel our feet forward. Over-pronation occurs
when the foot pronates too deep and for too long, not allowing the foot to 'recover' and supinate. Over-pronation hampers our natural walking pattern. It causes an imbalance and leads to wear and
tear in several parts of the body with every step we take.
There are many possible causes for overpronation, but researchers have not yet determined one underlying cause. Hintermann states, Compensatory overpronation may occur for anatomical reasons, such as
a tibia vara of 10 degrees or more, forefoot varus, leg length discrepancy, ligamentous laxity, or because of muscular weakness or tightness in the gastrocnemius and soleus muscles. Pronation can be
influenced by sources outside of the body as well. Shoes have been shown to significantly influence pronation. Hintermann states that the same person can have different amounts of pronation just by
using different running shoes. It is easily possible that the maximal ankle joint eversion movement is 31 degrees for one and 12 degrees for another running shoe.
Overpronation can be a contributing factor in other lower extremity disorders, such as foot pain, plantar fasciitis, ankle injuries, medial tibial stress syndrome (shin splints), periostitis, stress
fractures and myofascial trigger points. Overpronation increases the degree of internal tibial rotation, thereby contributing to various knee disorders such as meniscal injury or ligament sprains.
The effects of the postural deviation are exaggerated in athletes due to the increase in foot strikes while running and the greater impact load experienced. When running, three to four times the body
weight is experienced with each foot strike.2 If overpronation exists, the shock force is not adequately absorbed by the foot and is transmitted further up the kinetic chain.
If you have flat feet or low arches, chances are you overpronate. Although not always the case, the lower your arches the greater the overpronate. Stand on a hard surface (in front of a mirror if you
need to) and look at your feet, flat feet or low arches are easy to spot. If your feet look flatter than a pancake, have a look at your ankles and see if they seem collapsed or straight. If they are,
Non Surgical Treatment
Over-Pronation can be treated conservatively (non-surgical treatments) with over-the-counter orthotics. These orthotics should be designed with appropriate arch support and medial rearfoot posting to
prevent the over-pronation. Footwear should also be examined to ensure there is a proper fit. Footwear with a firm heel counter is often recommended for extra support and stability. Improper fitting
footwear can lead to additional problems of the foot.
Calcaneal "Slide" (Sliding Calcaneal Osteotomy) A wedge is cut into the heel bone (calcaneus) and a fixation device (screws, plate) is used to hold the bone in its new position. This is an aggressive
option with a prolonged period of non-weightbearing, long recovery times and many potential complications. However, it can and has provided for successful patient outcomes.