Various types of orthotics are used as part of treatment programs to improve patients' movement as well as balance and stability. To determine the appropriate orthotic for a patient, a range of factors are considered, including diagnosis, range of motion, strength, tone, cognition, dexterity, compliance sensation, edema, gait pattern, and pain.

Orthotic Options

Rigid Orthotics
Rigid, non-weight-bearing orthotics address foot imbalances but are not designed to address the biomechanics above the ankle. A flexible orthotic, measured in the weight-bearing position, is more appropriate for the entire human structure. Additionally, shock-absorbing qualities in these orthotics are critically valuable to the longevity of the structure.

A rigid orthotic is designed for an imbalanced foot; however, it offers no shock absorption for the entire structure. These orthotics last an eternity, but their restriction of normal foot mobility, their overcompensation of joints and muscles above the feet, and their absence of shock-absorbing qualities make flexible, weight-bearing orthotics preferable.

Ankle-Foot Orthoses
AFOs are commonly used in the treatment of disorders that affect muscle function, such as stroke, spinal cord injury, muscular dystrophy, cerebral palsy, polio, and multiple sclerosis.

AFOs can be used either by providing support to weak or wasted limbs or by positioning a limb with tight, contracted muscles into a more normal position. AFOs also are used to immobilize the ankle and lower leg in the presence of arthritis or fracture.

An AFO is usually made from plastic rather than metal to allow the brace to be lightweight and maintain better ankle control. The exception is when edema, impaired sensation, or marked skin-integrity issues are present. In this case, a metal AFO is preferable. Metal AFOs are attached to the patient's shoe, whereas plastic AFOs typically fit inside a variety of shoes. Thus, the plastic AFOs are considered more aesthetically appealing. To obtain a proper fit in shoes that the patient already has, the existing shoe insert may need to be removed and/or the toebox stretched.

The stability given to the ankle from an AFO can assist in decreasing ankle arthritic pain. However, because of the bulk of an AFO, lesser devices may be considered first. For example, a supramalleolar orthosis or ankle orthosis may suffice.

Orthotic Prescription

Assessing range of motion and strength, as well as the patient's ability for potential improvement, is important because improved range of motion can allow for better biomechanical alignment, and improved strength can allow for bracing with a less supportive device. If there is potential for improvement, the patient should be referred to physical therapy and a medical end point reached before a brace is prescribed.

Tone, dexterity, cognition, and compliance all affect orthotic design. For a patient with increased tone, tone inhibitors can be designed as part of the footplate to encourage rearfoot neutral, toe splaying, and extension. Decreased dexterity will necessitate a simple donning/doffing process. Impaired cognition and compliance issues also may necessitate a simpler design and step-by-step written instructions for the patient, which may include diagrams and a wearing schedule.

Impaired sensation and/or edema are precautions for orthotic fitting. These patients will be at a higher risk for skin issues and will need to monitor their skin response closely. Patients with notable edema should be cleared by a physician with regard to etiology of edema (cardiac, vascular, renal, etc) and stability of girth. If the patient is determined to be medically stable and appropriate for orthotic fitting, compression stockings may assist with edema management.

The patient's diagnosis and the purpose of the brace are crucial to appropriate prescription. Is the patient in pain? If so, is the pain due to arthritis, biomechanical faults, overuse, or trauma (ligament, bone, or muscle)? The causative factor must be taken into account when prescribing an orthotic device.

Alignment

Achieving a gait pattern with a minimum of deviations optimizes energy expenditure and decreases joint stress. While examining a patient's gait pattern, principles of normal biomechanical alignment should be used as a reference. Normally, at midstance, there is a slight varus moment at the knee. Deviation from this normal position puts increased pressure on the knee joint. At midstance, the rearfoot should be in the neutral position. If it is not, ankle and foot stress will increase.

The foot pronates from initial contact to midstance to assist with shock absorption, and supinates from midstance to preswing to act as a rigid push-off lever. If the foot's ability to absorb shock is impaired, this causes increased stress, which can contribute to lower-extremity and back pain. Any patient who presents with back pain should have their feet assessed.

Advantages of Orthotics

Custom-fitted, flexible orthotics are beneficial to patients for various conditions. For example, for degenerative joints, by fitting patients with shoe inserts designed to assist the body in dealing with the forces of walking (and running), a significant source of joint stress and excessive strain can be eliminated. This intervention results in a significantly better response to physical therapy care whenever degenerative joint disease is present.

Orthotics are helpful in two major ways: they support the joints and reduce biomechanical stress, and include viscoelastic polymers to decrease impact stress. Orthotics using these new biomaterials are designed to take the place of the inadequately functioning body tissues by absorbing the excessive forces of daily living, and by preventing (or at least slowing) further breakdown. Shock-absorbing viscoelastic polymers, along with improved biomechanics at the subtalar and knee joints, can achieve a substantial decrease in the amount of skeletal shock to joints. An additional recommendation for aging patients with loss of heel-pad compliance is the use of a heel cup, which improves heel-pad function by preventing lateral and medial bulging, thereby maintaining pad thickness.

Patients with degenerative changes in weight-bearing joints should receive optimal physical therapy care, including custom-fitted orthotics made with shock-absorbing materials. The viscoelastic materials that are available are lightweight, hold up well, and can significantly reduce the loads on degenerated joints from normal daily activities.

For hamstring injuries, a custom-made foot orthotic that helps position the rearfoot at heel strike can reduce overpronation, speed healing, and reduce the possibility of recurrence. Therefore, an important component must be a varus wedge (or "pronation correction") under the calcaneus. The use of man-made viscoelastic under the heel is needed to decrease the shock-wave transmission up the leg. And finally, sufficient support for the arches of the foot (especially the medial longitudinal arch) must be included to prevent prolonged pronation in the first half of the stance phase. An orthotic that incorporates all of these factors should be provided to athletes who want to return to full participation in their sport.

Balancing Act

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The goal of custom-made, flexible orthotics is to maximize the support provided by the feet, creating a more stable foundation. Orthotics also are used to improve balance and proprioception.

Postural balance is a specific and specialized function involving proprioception and is achieved when the body's center of gravity is maintained over the base formed by the feet.

Studies have shown that injuries to the lower extremity, whether acute or from chronic deformation, can alter proprioception and diminish the motor response of balance. The elderly are generally faced with cumulative traumas, combined with the degenerative conditions of ligament laxity and decreased afferent input. Therefore, new research that proves orthotics improve balance and proprioception is very encouraging.

With the development of new materials and processes, orthotics today are much more functional. New materials also help to reduce bacteria, moisture, and/or heat. The development of plastics and copolymers with different grades and flexibilities have allowed products to be prefabricated or custom-fit so that the orthotic maintains its integrity but is neither rigid nor as expensive.

Due to the complexity of orthotic intervention, a strong team approach is crucial to determining the optimal device and proper rehabilitation plan to achieve the best clinical outcome. Whether your patients lead sedentary lives or very active ones, injuries and joint-alignment problems can limit their ability to participate in activities. A properly prescribed and fitted orthotic can markedly improve function.

Carrie Lewis, DPT, is a home-based PT in Seattle who specializes in orthotics. Lewis can be reached at .