Orthotics are orthopedic devices designed to treat or adjust various biomechanical foot disorders. They may be simple, commercially made devices, such as cushioned heel cups or insoles for shoes. These are sold over-the-counter in drug stores or other retail establishments. The best orthotics, however, are custom-tailored devices specifically crafted to meet the needs of a particular individual. This is done by making an impression of the foot called a cast. The impressions in the cast duplicate any misalignments in the foot. Specialists in an orthotic laboratory can then correct the misalignments with compensation and stabilization techniques. The finished orthotic is then placed in the patient's shoe and helps keep the foot in proper alignment. Depending upon the patient's needs, the orthotic may have padding to cushion the foot against the weight of the body.

Types of Orthotics
In general, podiatrists group orthotics into four broad categories.

* Functional orthotics incorporate special wedges to adjust the heel or forefoot, correcting defects in the arch that cause poor shock absorption, such as excessive pronation (flattening of the arch) or supination (an arch that is too high).

* Weight-dispersive or accommodative orthotics typically feature padding designed to relieve pain caused by excessive pressure on the metatarsal heads. Other accommodative orthotics are designed to treat pain and pressure on the sesamoid bones, collapsed tarsal bones, sores and chronically inflamed toes.

* Supportive orthotics are arch supports usually prescribed to treat problems of the plantar arch.

* Early childhood orthotics are special devices designed to correct biomechanical walking problems identified in young children. They include splints, gait plates and night bars - devices used to hold a child's feet and legs at a proper angle while sleeping, thus promoting corrective adjustment for excessive toe-in or toe-out walking.

Who Should Use an Orthotic?
Because perfect feet are very rare, almost anyone can benefit from orthotics. They can prevent and alleviate many of the common foot complications that cause discomfort in otherwise healthy people. An analogy can be made between orthotics and eyeglasses. Both adjust bodily imperfections that inhibit people from functioning at their maximum physical potential. In both cases, a physician will do a complete examination and prescribe the proper amount of correction.

Almost anyone can achieve some benefit from an orthotic. There are several common symptoms that may indicate misalignment of the feet. You may be a candidate for orthotics if:

* one side of the sole of your shoe wears out faster than the other;
* you frequently sprain your ankle;
* you have chronic heel, knee or lower back pain;
* your shins hurt;
* your toes are not straight;
* your feet point inward or excessively outward when you walk; or
* your feet hurt in general.

Your feet should not hurt. Pain is the body's way of warning you something is wrong. If you ignore your pain, the condition causing it could become worse.

How Does an Orthotic Work?
To explain how orthotics function, it is important to understand the mechanics of walking. Each step, the vertical axis of the heel ideally should land almost perpendicular to the ground, with a slight inclination of only a few degrees toward the outside of the heel. From there, the weight is distributed progressively toward the lateral (outside) side of the foot. As the little (or fifth) toe starts to touch the ground, the arch of the foot should flatten slightly, shifting the body's weight toward the medial (inside) side of the foot. The heel then should start to lift off the ground, shifting the weight to the medial forefoot, principally the ball of the foot and the first.

This coordinated motion occurs in much less time that it takes to describe. It is, nevertheless, a complex process in which many things can go wrong. If a structural problem is present, the foot can collapse under the body's weight. Runners in particular exert much greater forces on their feet than those generated by simple walking. This can lead to more severe injuries, such as sprained ankles, shin splints and even fractures.

Over time, stresses on the feet can deform them. One of the foot's main functions is to absorb shock as the body's weight shifts with each step. It does this through a complex process in which the arch of the foot flattens slightly. This absorbs and distributes the weight throughout the entire foot. There are two major problems that can occur in this mechanism.

The first occurs when the arch does not flatten at all. This typically occurs in a person with a high arch, called a cavus foot. Because the arch does not flatten, it absorbs shock poorly. Instead of spreading it throughout the entire foot, the weight of the body falls only on the heel and the bases of the toes. This increases stress on the foot, especially the heel. Furthermore, because the weight is not absorbed well in the foot, it radiates up the leg to other joints. Over time, this can cause pain in the knees, hips and lower back.

To correct this condition, an orthotic is used to bring the ground into even contact with the rest of the foot. This allows the entire foot to support the weight of the body. Extra cushioning can be built into the orthotic so that some of the force does not even reach the foot.

A different problem results if the arch flattens too much. This is known as a planus or flat foot. In such cases, the weight distribution on the foot is too far on the medial side. A flat foot is unstable and cannot maintain a proper arch. Over time, the weight of the body on an unstable foot will cause the bones of the foot to become misaligned. This can lead to the development bunions, hammertoes and other foot deformities, as well as knee and lower back pain.

To address this problem, an orthotic with an increased arch will be prescribed to distribute the weight laterally. Depending on shape of the foot, the heel of the orthotic can be slanted to shift the weight more toward the center of the heel.

How Is an Orthotic Made?
While orthotics can be made by several different processes, most physicians prefer to make a plaster cast of the patient's foot. This is called a negative impression. The cast is sent to a laboratory with a prescription for recommended modifications. At the lab, a positive cast is made by pouring plaster into the negative cast. When this dries, it forms a perfect reproduction of the bottom of the foot. Using the physician's recommendations for corrections, the lab technicians custom-mold an orthotic that incorporates the necessary adjustments. This will provide the patient with the support, stability, cushioning and alignment necessary to keep his or her , ankles and lower body comfortable, healthy and pain-free.