Sunday, August 13, 2017

Foot Orthoses: What happened to the arch support?

A few decades back no self respecting perambulator would be seen around town without sporting a decent pair of arch supports in their shoes. Now of course these have become foot orthoses. Interestingly the term orthotic is commonly used to describe the new shoe inserts but this is not the noun but an adjective, so in proper talk the arch support has become the foot orthosis (singular) or foot orthoses (plural). There are two types of foot orthoses i.e. accommodative or functional orthoses.

Accommodative orthoses fill in dead space under the foot and are made from foams or polyurethane materials. These provide much needed cushioning or shock attenuation (dampen impact). Accommodative orthoses are available over the counter and come in full length, three quarter length, or heel cups. Foam materials have been tratitionally been used in accommodative devices but now it is more common to see new polymers incorporated into their structure. Visco-elastic materials are solids which contain gas and fluids and have the benefit pressure cannot pass through them so these have proved very useful in tempering shock.

Functional foot orthoses provide support to the moving (kinetic) foot. 'Orthos.' means straight (Latin), and a functional orthosis helps to re-establish closed chain motion. Not straighten exactly, and everyone is different, but some orthoses can help stabilise the moving (kinetic) foot. The theory is unstable feet caused by hypermobiliy in the joints contribute to painful conditions, ranging from heel to knee pain. These symptoms are from repetitive stress and insertable functional supports may relieve these problems by maintaining middle range motion of joints in the feet (stablising), thereby enforcing a rest to overused tendons, muscles and joints.

The arch component is often misleading and whilst a condition known as ‘collapsed arches’ is commonly spoken about it is a very rare event indeed. The height of the long arch of the foot is controlled by the position of the heel (in the frontal plane), so to achieve the highest arch. then tilt your heel inward. The reverse is also true. Customised Functional foot orthoses incline the heel and forefoot to make the foot act more efficiently. The arch section of the device has no other function than to tell left from right.

Custom devices are made specifically for individuals (usually to a plaster cast of the foot, but more use is now made of CAD and CAM technology) but pre-made devices can also be purchased over the counter. Made to measure foot orthoses are more costly and this is not always covered with health insurance. Experts warn us even the best foot orthoses cannot cure all, and even with devices good-quality shoes, stretching and training weak muscles also play an important role in becoming symptom free.

Efficatious claims that foot inserts relieve back problems is also something consumers need to take with a pinch of salt. In a review of scientific literature by the non-profit Cochrane Collaboration they found "limited evidence" insoles help back pain. Further a number of clinical trials in Australia involved testing the outcomes between bespoke and prefabricated foot orthoses and the researchers found no obvious advantage to bespoke foot orthoses when it came to preventing injuries or reducing pain. So it is very much a case of buyer beware and the advice of the American Orthopaedic Foot & Ankle Society is for all general consumers to seek out information to help you choose which type of foot orthoses you need with the pharmacist, podiatrist, pedorthist, and physiotherapist a good place to start.

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