Over-Pronation

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Overview

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.Overpronation

Causes

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.

Symptoms

Overpronation can lead to injuries and pain in the foot, ankle, knee, or hip. Overpronation puts extra stress on all the bones in the feet. The repeated stress on the knees, shins, thighs, and pelvis puts additional stress on the muscles, tendons, and ligaments of the lower leg. This can put the knee, hip, and back out of alignment, and it can become very painful.

Diagnosis

You can test for pronation by looking at the leg and foot from the back. Normally you can see the Achilles Tendon run straight down the leg into the heel. If the foot is 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.Overpronation

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. Improperly fitting footwear can lead to additional foot problems.

Surgical Treatment

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%.
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