Pronation is a normal motion which occurs after heel strike during walking. As the foot moves towards toe off, the foot naturally should move from an outside path towards the midline of the body stopping at neutral in ideal conditions. Overpronation is the foot?s motion past neutral and moving excessively toward the bodies midline. Overpronation can be caused by a number of factors including internal rotation of the femur or thigh bone, internal torsion of the tibia or shin bone, being genu valgum or ?knock kneed?, as well as fixed deformities of the ankle and forefoot. The overpronating foot is often hypermobile meaning it has excessive range of motion in the foot joints.
In adults, the most common reason for the onset of Over-Pronation is a condition known as Post Tibial Tendonitis. This condition develops from repetitive stress on the main supporting tendon (Posterior Tibial Tendon) of the foot arch. As the body ages, ligaments and muscles can weaken. When this occurs the job of providing the majority of the support required by the foot arch is placed upon this tendon. Unfortunately, this tendon cannot bear the weight of this burden for too long. Eventually it fatigues under the added strain and in doing so the foot arch becomes progressively lower over a period of time.
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, you’re overpronating.
Non Surgical Treatment
Solutions typically presented will include physical therapy sessions, prolonged prescription drug regimens, occasionally non-traditional approaches like holistic medicine and acupuncture. These options can provide symptom relief in the short term for some patients. However, these treatment methods cannot correct the internal osseous misalignment. Ligaments are not effective in limiting the motion of the ankle bone when excessive joint motion is present. Furthermore, there is not a single, specific ligament that is “too tight” that needs to be “stretched out.” The muscles supporting the bones are already being “over-worked” and they cannot be strengthened enough to realign these bones. There is no evidence to suggest that any of these measures are effective in re-establishing or maintaining the normal joint alignment and function.
Hyperpronation can only be properly corrected by internally stabilizing the ankle bone on the hindfoot bones. Several options are available. Extra-Osseous TaloTarsal Stabilization (EOTTS) There are two types of EOTTS procedures. Both are minimally invasive with no cutting or screwing into bone, and therefore have relatively short recovery times. Both are fully reversible should complications arise, such as intolerance to the correction or prolonged pain. However, the risks/benefits and potential candidates vary. Subtalar Arthroereisis. An implant is pushed into the foot to block the excessive motion of the ankle bone. Generally only used in pediatric patients and in combination with other procedures, such as tendon lengthening. Reported removal rates vary from 38% – 100%, depending on manufacturer. HyProCure Implant. A stent is placed into a naturally occurring space between the ankle bone and the heel bone/midfoot bone. The stent realigns the surfaces of the bones, allowing normal joint function. Generally tolerated in both pediatric and adult patients, with or without adjunct soft tissue procedures. Reported removal rates, published in scientific journals vary from 1%-6%.