Orthotic Options

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March 2003

By Dorothy D. Aiello, PT, MS, and Patrick George, CPO

The art of orthotics is to achieve a balance between stability and mobility. Bracing is used to enhance stability, but it is very important not to overbrace and thereby limit mobility. The brace should be lightweight and durable.

ORTHOTIC PRESCRIPTION

Determining the appropriate orthotic for a patient involves considering a range of factors including diagnosis, range of motion, strength, tone, cognition, dexterity, compliance sensation, edema, gait pattern, and pain. Some orthotics are designed for specific diagnoses; these will be described in detail in the orthotic subsections. 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 endpoint 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 may also 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 medical doctor in 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.¹ 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.

KNEE ORTHOSES

There are two types of knee orthoses (KOs): 1) patellofemoral joint orthoses, and 2) tibiofemoral joint orthoses.² Patellofemoral orthoses are prescribed for patellofemoral joint dysfunction and are primarily designed to assist proper patella tracking during knee movement and to minimize patellar compression.^2,3 They may also be used for neutral warmth and pressure to decrease muscular pain or chondromalacia. Tibiofemoral KOs are prescribed for patients’ post-knee surgery, with arthritic changes, ligament laxity, and/or pain.

Patellofemoral orthoses are made with and without hinges, depending on the degree of control needed. There are several patella pad designs that include the H buttress, horseshoe, donut, and infra-patella half moon buttress. The H buttress provides patella support for chondromalacia, patella tendonitis, subluxation, and Osgood-Schlatter disease. The horseshoe patella design is indicated for the former as well, but does not extend as far distally. The donut-style support provides circumferential control for patellofemoral disorders and the inferior patella support, infrapatella half moon buttress, is specifically intended for the treatment of patella tendonitis and Osgood-Schlatter disease.

Tibiofemoral KOs can be further subclassified into rehabilitative, functional, and prophylactic.⁴ Rehabilitative orthoses are designed to provide protection by controlling motion of the knee after surgery or injury. The goal is to return the patient back to normal activities in the shortest and safest period. Often a KO with adjustable hinges is used. For example, after repair of an anterior cruciate ligament, a hinged KO is usually used that allows motion within the patient’s available range and can be easily adjusted to allow more motion as the patient progresses.

Functional knee braces are used to provide external stability during physical activity.^2,5 They are designed to limit abnormal displacement or loads that may be harmful to the injured, arthritic, or reconstructed knee. Since many knee orthoses are available off the shelf, it is often possible to trial the patient with one. This gives the orthotist the opportunity to evaluate the impact on pain as well as functional mobility.

A hinged KO or a joint unloading KO may be used to alleviate arthritic pain. Since there is a varus moment at the knee during most of the stance phase, knee osteoarthritis is more common in the medial compartment than the lateral compartment.⁶ Joint unloading KOs are designed to unload the arthritic joint compartment by using a three-point pressure system. These braces can be made with single or dual joints. When addressing degenerative changes of the medial or lateral compartment in the absence of other instabilities, a single upright should suffice. However, when a patient presents with multiple instabilities, the condylar pads are adjustable to provide control in the sagittal, coronal, and transverse planes.

Prophylactic KOs are designed to protect athletes from injury without hindering knee mobility. An example of a prophylactic KO is a neoprene wrap or sleeve. In theory, this should increase the awareness of a compromised knee joint, thereby decreasing the risk of injury. There is currently a great deal of controversy as to the appropriateness of using prophylactic KOs.⁴

ANKLE-FOOT ORTHOSES

An ankle-foot orthosis (AFO) is usually made out of 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 cosmetically 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 should be considered first. For example, a supramalleolar orthosis (SMO) or ankle orthosis (AO) may suffice.

SMOs, AOs, AND UC BERKELEY LABORATORY ORTHOSES (UCBLs)

According to Lin, “the design of an SMO mimics the effect of a high-top sneaker or shoe but provides more intimate control of the ankle-foot complex because of its custom-molded fabrication.”⁷ An SMO is indicated to assist in controlling ankle medial-lateral stability during stance, but because of the shortened lever arm it is not considered to be very effective in controlling sagittal plane motion.⁷ An SMO can also control for rearfoot position and pronation/supination of the foot.

If the only goal is to provide mediallateral control of the ankle, an AO will usually suffice. This can be helpful to decrease risk of ankle sprain in athletes. It can be easily applied by the user and does not require assistance from an athletic trainer. AO options include lightweight sports plastic/Velcro models, hinged AOs, lacing AOs, neoprene sleeves, and ankle wraps. Some AOs include a heat-moldable arch for the foot.

A University of California at Berkeley Laboratory orthosis (UCBL) is indicated to control rearfoot position as well as mid-tarsal joint position during stance. If the patient does not require medial-lateral ankle support, this can be an appropriate option for a lesser device. However, the clinician should consider that typically this type of orthotic requires a longer period of time to wean into as compared to a traditional AFO.

Athletes can benefit from the UCBL design that maintains proper biomechanical alignment during strenuous activities. Without this control, flexible pes planus can cause the heel to evert the midfoot and result in pronation and internal rotation of the tibia. This can result in medial knee pain and it may also affect the hip or low back.

FOOT ORTHOTICS

Orthotic intervention for the foot is a very complex subject. Generally, the goal of foot orthotics is to decrease pain and improve function. More specifically, they may accommodate or correct deformities, and provide shock absorption for the foot.⁸

There are soft, over-the-counter orthotics that assist in shock absorption. Some of these provide some arch support also. These soft orthotics are generally inexpensive and may be appropriate for patients with minimal biomechanical faults. However, for significant biomechanical issues, a custom orthotic is necessary. A custom orthotic may be soft, semirigid, or rigid.

Custom soft orthotics are indicated to protect deformed or disvascular feet and are made from forgiving materials. However, a soft orthotic may not provide enough control and a rigid orthotic may be too controlling. Semirigid orthotics are generally a good functional choice to provide adequate support and shock absorption. They are fabricated from multidurometer materials that provide graduated degrees of control.

To address both biomechanics and shock absorption, you may wish to recommend a custom semirigid orthosis with a soft, shock-absorbing cover.

FOOTWEAR

Since shoes are the foundation for the orthotic device, they also need to provide good structural support. They should have a firm heel counter to properly support the rearfoot, and lacing or Velcro closure to assist in proper foot position. This section will provide a brief overview of some orthopedic shoe modifications.

There are several possible shoe modifications. For orthopedic diagnoses, some options are a steel shank, shoe lift, rocker bottom, and double rocker bottom. A steel shank is used for patients with hallux rigidus to decrease pain by limiting foot motion with walking. A lift is indicated to correct for a leg length discrepancy; typically, 3/8 inch or less is accommodated for within a shoe and greater than 3/8 inch modification is attached to the outside of the shoe.

By decreasing mid-foot motion and metatarsal stress, a rocker bottom may alleviate foot and ankle pain in arthritic patients.¹ There is a new shoe design that has a heel spring cushioned orthotic “double-rocker.” In preliminary studies, this design shows promise for improving shock absorption and decreasing pain.⁹

CONCLUSION

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 you lead a sedentary life or a very active one, injuries and joint alignment problems can limit your ability to participate in activities. A properly prescribed and fitted orthosis can markedly improve function.

Dorothy D. Aiello, PT, MS, is Orthotic Clinic Coordinator at Spaulding Rehabilitation Hospital, Framingham, Mass. She is currently involved in a project with MIT and Spaulding to design a prototype lower leg brace.

Patrick George, CPO, is a certified orthotist and prosthetist. His areas of expertise include sports bracing and bracing for neuromuscular disorders.

References

Bordelon RL. Orthotics, shoes and braces. Orthop Clin North Am. 1989;20:751-7.
Nawoczenski DA, Epler ME. Orthotics in Functional Rehabilitation of the Lower Limb. Philadelphia: WB Saunders Inc; 1997.
Eisele SA. A precise approach to anterior knee pain. Phys Sports Med. 1991; 19:126-139.
Schlegel TF, Steadman JR. Knee orthoses for sports-related disorders. In: American Academy of Orthopedic Surgeons: Atlas of Orthoses and Assistive Devices. 3rd ed. St Louis: Mosby Inc; 1997:415-426.
Knecht JF. Knee orthoses. In: Lusardi MM, Nielson CC, eds. Orthotics and Prosthetics in Rehabilitation. Boston: Butterworth Heinemann; 2000:177-190.
Kerrigan DC, Edelstein JE. Gait. In: Gonzalez EG, Myers SJ, Edelstein JE, Liberman JS, Downey JA, eds. Downey & Darling’s Physiological Basis of Rehabilitation Medicine. Boston: Butterworth Heinemann; 2001:397-416.
Lin RS. Ankle-foot orthoses. In: Lusardi MM, Nielson CC, eds. Orthotics and Prosthetics in Rehabilitation. Boston: Butterworth Heinemann; 2000:159-175.
Nole R, Garbalosa JC. Functional foot orthoses. In: Lusardi MM, Nielson CC, eds. Orthotics and Prosthetics in Rehabilitation. Boston: Butterworth Heinemann; 2000:129-158.
Kleinkort JA, Ungerleider BI. Report of a new orthotic shoe design with heel coil spring assist. Orthopedic Practice. 2002;14(4):44-45.

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March 2003