Over-pronation is very common and affects millions of Australians. To better understand this condition, we'll take a closer look at the 3 most common foot types. An estimated 70% of the population has fallen arches (or a low arch). Only 20% have a normal arch. And 10% have abnormal feet, in other words they either have flat feet or the opposite, a high arched foot. Most of us have a low arch. The foot actually appears quite normal and a clear (but low) arch is present under the foot, especially when sitting down. The situation changes with weight-bearing: when we get up the arch lowers. When we start walking the arches collapse and the ankles roll inwards. This is called over-pronation or fallen arches. Over-pronation is not the same as flat feet as often noted.
Unless there is a severe, acute injury, overpronation develops as a gradual biomechanical distortion. Several factors contribute to developing overpronation, including tibialis posterior weakness, ligament weakness, excess weight, pes planus (flat foot), genu valgum (knock knees), subtalar eversion, or other biomechanical distortions in the foot or ankle. Tibialis posterior weakness is one of the primary factors leading to overpronation. Pronation primarily is controlled by the architecture of the foot and eccentric activation of the tibialis posterior. If the tibialis posterior is weak, the muscle cannot adequately slow the natural pronation cycle.
Overpronation causes alterations in proper muscle recruitment patterns leading to tightness in the outside of the ankle (lateral gastrocnemius, soleus, and peroneals). This tightness can lead to weakness in the opposing muscles such as the medial gastrocnemius, anterior tibialis, and posterior tibialis. If these muscles are weak, they will not be able to keep the knee in proper alignment, causing the valgus position. All this tightness and weakness can cause pain within the ankle, calf, and knee region. And it can send imbalance and pain all the way up to the upper back, if deep core strength is lacking and can't hold the pelvis in neutral.
Bunions, calluses and crooked toes may indicate alignment problems. So, it is important to ascertain the condition of a client's toes. Check the big toe to determine if the first joint of the toe is swollen, has a callus or bunion, and/or looks as though it abducts (i.e., hallux valgus) rather than pointing straight ahead. Also, look to see if the lesser toes seem to "curl up" (i.e., the person has hammer or claw toes). This may be indicative of damage to, or inflexibility of the plantar fascia caused by excessive flattening of the foot.
Non Surgical Treatment
Adequate footwear can often help with conditions related to flat feet and high arches. Certified Pedorthists recommend selecting shoes featuring heel counters that make the heel of the shoe stronger to help resist or reduce excessive rearfoot motions. The heel counter is the hard piece in the back of the shoe that controls the foot?s motion from side-to-side. You can quickly test the effectiveness of a shoe?s heel counter by placing the shoe in the palm of your hand and putting your thumb in the mid-portion of the heel, trying to bend the back of the shoe. A heel counter that does not bend very much will provide superior motion control. Appropriate midsole density, the firmer the density, the more it will resist motion (important for a foot that overpronates or is pes planus), and the softer the density, the more it will shock absorb (important for a cavus foot with poor shock absorption) Wide base of support through the midfoot, to provide more support under a foot that is overpronated or the middle of the foot is collapsed inward.
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%.