Technical Glossary

Here are the definitions of some of the medical terms used when talking about orthotic treatment, to help you understand more about foot biomechanics.

Orthotics are devices which fit into the shoe to aid the foot. "Functional orthotics" are rigid and designed to control motion and correct the function of the foot. Individuals with flatfeet, tendonitis, plantar fasciitis, certain foot deformities, knee, hip and back problems may benefit from functional orthotics. "Accommodative orthotics" are soft and designed to reduce pressure and prevent excess friction. Diabetics and those with a loss of sensation or circulation in their feet will benefit from accommodative orthotics. Both types of orthotics are custom made by taking a mold of the foot.

Functional Orthotics

The goal of the functional orthotic is to improve the mechanics of the foot, control the abnormal motion in the foot, decrease the pain in the foot, ankle, knee, hip or back and to add support. The orthotic should make standing, walking, jogging or running more comfortable. The orthotic must be rigid to help control the motion in the foot and add support. If the orthotic is soft, the weight of the body would collapse the device and it would no longer function.

Abnormal motion is typically in the form of pronation. Pronation is the rolling in of the foot and collapse of the arch. The motion starts at the rearfoot, or heel area. When the heel turns in, it allows the arch to collapse. This puts undue stress on the ligaments and tendons in the arch area and contributes to the development of tendonitis, plantar fasciitis, bunions and hammertoes. The functional orthotic helps to control the abnormal motion in the rearfoot. This is accomplished by taking a mold of the foot in its neutral position. The neutral position is the position the foot should be in when walking. When standing, the over-pronated foot is in the uncorrected position. The mold of the foot should be taken with the patient sitting so the foot can be placed in the neutral position.

The molds are sent to a lab and scanned into a computer. A reverse image is produced and the computer generates an image of the foot in neutral position. The computer adjusts the image based on the corrections recommended by your podiatrist. A model of the foot is then cut out, in some cases out of wood. The orthotic material is pressed over the foot model and the orthotic is created. The most common material is polypropylene, but other materials, such as graphite are used. In some cases, hand-made molds are created out of plaster. This was the classic way orthotics were made until newer technology made the process much less labor intensive.

Functional orthotics are a successful treatment for many problems affecting the lower extremity. In a recent article in the Journal of the American Podiatric Medical Association, 75% of patients surveyed had good to excellent results from functional orthotics. This includes 17% who felt the orthotics "cured" their pain. Less than 10% had no relief. The most commonly treated condition in the study was a painful heel. Over 20% of patients surveyed were treated for a painful heel and 20% were treated for a painful arch. Fourteen percent of the individuals were using orthotics for flatfeet. Other conditions treated with orthotics were knee, hip and back pain, foot arthritis, bunions and high arches. Tendonitis was not specifically evaluated.

Individuals with plantar fasciitis (heel and arch pain) who also have flatfeet usually respond best to orthotics. The plantar fascia is a ligament type structure on the bottom of the foot which helps to hold up the arch. When the foot collapses, the weight of the body stresses the ligament and results in tearing and inflammation. This results in plantar fasciitis. These individuals typically respond well to orthotics in combination with other treatments. Certain types of tendonitis respond well to orthotics and other types require orthotics. Posterior tibial tendonitis is the tearing and inflammation of the tendon that helps to hold up the arch. When this tendon is overstressed by arch collapse it cannot heal. Orthotics are essential in the treatment of this condition.

Biomechanics	The study of how forces affect the human body. Body mechanics and function.
External rotation	Outward rotation.
Internal rotation	Inward rotation.
Instability	Lack of steadiness and efficiency.
Neutral position	The 'central' position of the foot whereby there is no pronation or supination occurring. This is generally the most efficient foot position.
Polypropylene	Thermopolymer used in the manufacture of foot orthoses.
Pronation	The rolling inwards of the foot including lowering of the arch and inward tilting of the heel. The pronated foot is generally an unstable and inefficient foot type, prone to injury.
Supination	The rolling outwards of the foot. This foot is high arched, lacks flexibility and is a poor shock absorber.
Symptoms	Any abnormality of function, structure or sensation as experienced by a person.
Varus	Tilted towards the outside of the body.