Pronation is a turning outward of the foot at the ankle, which allows the foot to flatten. The pronation helps to absorb some of the compressive shock forces, torque conversion, adjustment to uneven ground contours, and maintenance of balance. It is necessary to have a certain amount of pronation to disseminate the energy of the foot-strike. If there is too little or too much pronation injuries may occur.
When a foot and ankle pronates to a great degree, we call it over-pronation. Normally you can see the Achilles Tendon run straight down the leg into the heel. If the foot is over-pronated, the tendon will run straight down the leg, but when it lies on the heel it will twist outward. This makes the inner ankle bone much more prominent than the outer ankle bone.
There is a relationship between biomechanics and injury that is specific to each body part. Overall though, poor mechanics will either increase the landing forces acting on the body or increase the work to be done by the muscles. Both increase the stress, which depending on the individual and the amount of running, can become excessive and cause injury.
Because pronation is a twisting of the foot, all of the muscles and tendons which run from the leg and ankle into the foot will be twisted. In over-pronation, resulting laxity of the soft tissue structures of the foot and loosened joints causes the bones of the feet to shift. When this occurs, the muscles which attach to these bones must also shift, or twist, in order to attach to these bones. The strongest and most important muscles that attach to our foot bones come from our lower leg. So, as these muscles course down the leg and across the ankle, they must twist to maintain their proper attachments in the foot. Injuries due to poor biomechanics and twisting of these muscles due to over-pronation include: shin splints, Achilles Tendonitis, generalized tendonitis, fatigue, muscle aches and pains, cramps, ankle sprains, and loss of muscular efficiency (reducing walking and running speed and endurance). Foot problems due to over-pronation include: bunions, heel spurs, plantar fasciitis, fallen and painful arches, hammer toes, and calluses.
An orthotic is a device inserted inside the shoe to assist in prevention and/or rehabilitation of injury. Orthotics support the arch, prevent or correct functional deformities, and improve biomechanics.
Prescription foot orthoses are fabricated utilizing a three dimensional representation of the plantar foot and are specifically constructed for an individual using both weightbearing and non-weightbearing measurement parameters and using the observation of the foot and lower extremity functioning during weightbearing activities.
Non-prescription foot orthoses are fabricated in average sizes and shapes in an attempt to match the most prevalent sizes and shapes of feet within the population without utilizing a three dimensional representation of the plantar foot of the individual receiving the orthosis.
Research in support of orthotics:
Studies have shown that the most effective way to decrease a high Q angle and lower the biomechanical stresses on the knee joint is to prevent excessive pronation with custom-made flexible orthotics. One study found that using soft corrective orthotics was more effective in reducing knee pain than a traditional exercise program. A more recent study showed that Q angle asymmetries, secondary to excessive pronation affecting knee alignment, can be effectively controlled or corrected utilizing custom-made, flexible orthotics. Another project involving meof a running club determined that 75% of those using orthotics eliminated or greatly reduced pain in the feet, ankles, shins, knees and hips
Relief of pain
The ability to return to previous levels of activity
Reduction in the degree and duration of pronation