Orthotics

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Overview

Orthotics are orthopedic devices that are used to alter or modify foot function and are designed to treat, adjust, and support various biomechanical foot disorders. Some orthotics are simple, commercially-made devices, such as cushioned heel cups or insoles for shoes that are sold over the counter in drug stores or other retail establishments.

The most effective orthotics, however, are custom-made devices that are crafted to meet the specific needs of a particular individual. Custom orthotics are created using an impression of the foot called a cast, which duplicates any misalignments in foot structure. Using the cast and computer technology, technicians in an orthotic laboratory design a device that balances out deformities and corrects misalignments.

The finished orthotic is placed in the patient's shoe to support the foot and eliminate abnormal foot biomechanics by keeping the foot properly aligned. Depending on the patient's needs, the orthotic may have padding to cushion the foot and make it more comfortable.

With & Without an Orthotic Click on the image to view a larger version.

Types of Orthotics

In general, foot care specialists group orthotics into the following categories:

• Functional orthotics are designed to support abnormal foot biomechanics. These devices, which often are made of supportive plastic polymer materials, prevent abnormal foot pronation (flattening of the arch) and reduce the impact load from the ground (shock absorption) while walking or running. Functional orthotics allow the foot to become a mobile adapter and a rigid lever. They support the rear foot or subtaylor joints, as well as the midfoot or midtarsal joints. This support stabilizes the foot and can help prevent repetitive overuse injuries. Functional orthotics are used to correct many foot deformities.

• Accommodative orthotics typically feature a soft supportive device that is designed to relieve mild foot pain and correct minor foot problems. These devices often are used to correct biomechanical walking problems in young children. Accommodative orthotics include include splints, gait plates, and night bars (devices used to hold a child's feet and legs at a proper angle while sleeping) that promote corrective adjustment for excessive toe-in or toe-out walking. Braces may be used in infants to correct foot, leg, or hip abnormalities (e.g., metatarsus adductus, internal or external hip rotation problems).

Who Should Use an Orthotic?

Almost anyone, from children to adults, can benefit from orthotics. Orthotics can alleviate many common foot problems that cause pain and discomfort in otherwise healthy people. An analogy can be made between orthotics and eyeglasses—both devices adjust problems that can impair physical function. In both cases, a physician (e.g., eye doctor or foot care specialist) performs a complete examination and then prescribes the proper amount of correction.

There are several common symptoms that may indicate misalignment of the feet. These signs and symptoms include the following:

• Abnormal shoe wear (e.g., one side of the sole of the shoe wears out faster than the other)
• Bunions
• Chronic heel (e.g., plantar fasciitis), knee, or low back pain
• Flatfeet
• Frequent ankle sprains
• Gait abnormalities (e.g., feet point inward or excessively outward during walking)
• Shin pain (e.g., shin splints)

The feet should not hurt and pain indicates that something is wrong. If foot pain is not properly treated, the condition causing it may worsen. Relief is closer than you think. Use our DPMLocator to find a foot care specialist near you.

How Does an Orthotic Work?

To explain how orthotics function, it is important to understand the mechanics of walking. With each step, the vertical axis of the heel ideally should land slightly inverted to the ground, with an inclination of only a few degrees toward the outside of the heel. From there, the foot begins to pronate (flatten) and then comes off the ground at the toes (resuppinates). So, during each step, weight shifts from laterally to medially and back to laterally. A properly designed orthotic controls how the foot strikes the ground, absorbs shock, and reduces stress in the foot.

This coordinated motion is 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. Over time, stress on the feet can result in deformities. Running exerts much greater force on the feet than walking and can lead to more severe injuries, such as sprained ankles, shin splints, and fractures.

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 problem 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 the weight throughout the entire foot, it falls only on the heel and the base 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 adjust and even out the contact between the foot and the ground. This allows the entire foot to support the weight of the body. Also, extra cushioning can be built into the orthotic so that some of the force does not reach the foot.

A different problem results when the arch flattens too much. This is known as a planus or flatfoot. In this condition, the weight distribution on the foot is too far on the medial side. A flatfoot is unstable and cannot maintain a proper arch. Over time, the weight of the body on an unstable foot can 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 low back pain.

To address this problem, an orthotic with an increased arch can 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.

While orthotics can be made in several different ways, 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 and is removed, 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 made of a supportive material that incorporates the necessary adjustments. The orthotic provides the patient with the support, stability, cushioning, and alignment necessary to keep the feet, ankles, and lower body comfortable, healthy, and pain-free.

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