Orthotics: evaluation, intervention, and prescription

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Orthotics: evaluation, intervention, and prescription

HEIDI TRUMAN, CPO and WALTER RACETTE, CPO

Overview

An orthosis is an external device that produces a force that biomechanically affects the body to correct, support, or stabilize the trunk, the head, and/or an extremity. The goals in patient care with orthotic use vary from temporary application to permanent usage to maintain improvement. Orthoses are named by the sections of the body to which they are applied. For example, an orthosis that controls and covers the ankle and foot is called an ankle-foot orthosis (AFO). The abbreviations for the device are used by professionals in clinical documentation. Many factors enter into the decision regarding use and type of orthosis, and these will be discussed later. It is essential that the least complicated and most cost-effective orthosis be applied to the patient. The rehabilitation team must build a priority list of desired outcomes and accept that sometimes all of the items on the list may not be achieved by either the orthosis or the patient-team combination. At the very least, care must be attempted in stages because the patient’s condition changes or other medical concerns may arise. For example, an excessive number of custom-made and custom-fit plastic AFOs have been issued because they are “more cosmetic and lighter” than AFOs made of metal and leather material. There are times when all higher-priority goals can be achieved so that down the list the goals of cosmesis and light weight can be considered (Table 34-1). However, in the case of neuropathy of the foot, significant risk would be incurred by providing a total contact AFO made of plastic to keep it lightweight. A double-upright metal AFO with a well-fitting extra-depth shoe with a custom accommodative insert would fit the patient’s needs and take into consideration the sensory and motor changes within the lower extremity. Effective coordination and communication between health professionals in development of patient goals is essential during the evaluation process. For example, a design criteria omission as simple as placing a loop closure on the side that the patient cannot reach will prohibit the use of the orthotic device. A sound understanding of biomechanical and orthotic principles as well as skilled patient management techniques must be used to be successful with patients who require orthoses.

TABLE 34-1 image

COMPARISON OF METAL AND PLASTIC ORTHOSES

FACTOR METAL AND LEATHER POLYPROPYLENE LAMINATION OR GRAPHITE POLYETHYLENE
Adjustability Yes Yes, with heat No Yes, with heat
Patient changes shoes No Yes Yes Yes
Weight-bearing strength Yes Yes Yes No
Skin at risk Yes Yes, close observation No Yes
Best spinal use No Yes No Yes
Long-term wear Yes Less Yes Least
Weight (lightest at 1) 4 2 3 1
Adjustability to changing clinical picture Yes Limited unless initial articulation fabricated No No
Short-term need Yes Yes Yes Yes
Requires corrective force with good patient sensation Fair Good Fair Good
Patient compliance, ability, or direction Best Questionable No Fair
Ability of clinician to change angulation, ankle or knee Best Limited* No Not indicated for weight bearing
Upper-extremity fabrication-direct mold highest frequency Limited Yes Limited Yes

image

*Use in combination with metal joints produces best results.

There are similarities in orthotic management of orthopedic and neurologically impaired patients; however, the neurological population presents additional factors that challenge prescription criteria and outcomes for the rehabilitation team. Lack of proprioception, impairments in sensation, and spasticity are some of these special considerations. Concurrent medical issues, problems with communication, and caregivers may complicate patient management.

The advancements in and access to medical technology have had a profound effect in the field of orthotics. The evolution of plastic, composite, and metals fabrication technology has dramatically improved the ability to control, support, and protect all areas of the human body. Today, patients are fit for custom and prefabricated orthotic devices that provide a variety of functions in both a timely and cost-effective manner. These factors have led physicians to routinely prescribe orthoses for a wide range of medical conditions, whereas in prior decades lack of availability and shortage of experienced orthotists restricted patient access and narrowed the use of orthoses.1 Orthoses are important options for postoperative management, acute fracture management, and adjunct treatment, in addition to more traditional uses. For many, the proliferation of the prefabricated orthosis signaled a dilution of quality orthotic care, but in reality it has had the opposite effect. These readily available, cost-effective orthoses have not taken orthoses out of the hands of the orthotist but rather have moved them into the minds of treating professionals. There has been continued growth of new and improved orthoses and expansion into other areas of treatment previously lacking in orthotic management. For example, positional and corrective orthoses can be used for premature and newborn infants, and a wide range of sizes of orthoses that previously were made only in adult sizes have become available for pediatric patients. As with any new technological advancement, there has been incorrect application and use. It is not that many of these prefabricated orthoses are difficult to apply; rather, there has been lack of a clear understanding of the indications, contraindications, and limitations these devices present to the orthotist and other health professionals such as occupational and physical therapists.

Advancements in technology have allowed the use of lighter, stronger materials in the fabrication of lower-extremity orthotics. Specifically, the substance called preimpregnated carbon is a graphite fabric with an exact amount of resin and catalyst already incorporated into the material. With the fibers properly directed over a model, it can be formed with heat. Graphite in other forms has been used in both prosthetics and orthotics for years. However, it had limited acceptance in orthotics because it did not significantly reduce the weight of the orthosis compared with other materials. It also lacked the properties to enable modification of the orthosis after the lamination process. The preimpregnated graphite has a dramatically reduced weight, still maintains its strength, and gives the orthotist the opportunity to use the dynamics of loading and response during the gait cycle. This allows for assistance in both the swing and stance phases of gait (Figure 34-1). A clinical example at the end of this chapter demonstrates this need in patient management.

Another significant advancement in component technology has been the introduction of weight-activated orthotic knee joints. Although available in prosthetics for decades, the development of a lightweight, compact knee joint that would allow a patient to have knee stability during stance2 and clearance during swing phase has been elusive until recently. Before this, the available knee joints for knee-ankle-foot orthoses (KAFOs) involved some type of locking mechanism that remained locked throughout the gait cycle. The joint provided stabilization of the weak quadriceps musculature during stance but kept the knee in a fully extended position, making advancement of the limb in swing more difficult for the patient. There are specific indications and contraindications for stance control KAFOs, but early results are promising. This feature can significantly reduce energy output,3 as it is not necessary to raise the center of gravity to clear the locked knee during swing phase. This improves patient safety when walking on uneven surfaces. New technology for externally powered knee orthoses has just entered the market. These “bionic legs” are robotic aids worn during therapy sessions for gait training. They assist and augment the strength of the patient’s muscle and are most typically used in post–cerebrovascular accident (CVA) rehabilitation. Once the patient has achieved functional improvements, the use of the orthosis is discontinued.

Other advancements in orthotic technology include the development of neuroprosthetic devices. These devices act through circuitry and programming to substitute for a deficit in the neural system. Functional electrical stimulation (FES) is a method of applying low-level electrical currents to motor nerves to restore function. In the 1960s the application of FES for foot drop was demonstrated by using a simple single channel to stimulate the common peroneal nerve to activate the ankle dorsiflexors. FES has widespread applications in many other neuroprosthetic devices such as cardiac pacemakers, cochlear stimulators, bladder stimulators, and phrenic nerve stimulators. Until recently, FES devices to provide ambulation assistance were large, unreliable, complex, and restricted to use in a therapy setting. The FES used in neurological rehabilitation attempts to unmask existing voluntary control (if any) and/or initiate dormant activity of the nerves and muscles. For FES to be used, the patient must have an upper motor neuron lesion. This means the nerve-to-muscle pathway is intact and the reflex arc is undamaged. Goals of FES address many rehabilitative outcomes. FES can reduce spasticity, synergy patterns, swelling, and blood clot formation as well as maintaining range of motion (ROM). FES used in gait can improve overall walking abilities by dorsiflexing the foot during swing to provide foot clearance, control initial contact, increase safety, decrease energy expenditure, and retrain muscles. FES has some application in the upper extremity as well, although at this time it is purely in a therapeutic setting. Currently, there are several FES units for foot drop on the market. These devices are used by patients in their daily lives and are not limited to the rehabilitation setting. The WalkAide from Innovative Neurotronics (Figure 34-2) and NESS L300 from Bioness (Figure 34-3) both function to provide dorsiflexion during the swing phase by stimulating the peroneal nerve. An ideal candidate for these devices must have an upper motor neuron lesion, good control of the knee joint, and drop foot. Common neurological conditions in which these devices are used are CVA and multiple sclerosis (MS). Both devices involve some sort of sensor to determine when the patient is initializing the swing phase of the gait cycle and send an electrical stimulus to the nerve to dorsiflex the foot. Advantages of functional FES over traditional orthotic management for foot drop are that it shifts an orthotic device from being a passive support to providing active assistance. FES stimulates the patient’s muscles to lift the foot, rather than acting as a passive splint to hold the foot.

Future developments in the field of orthotics will provide external power and support for patients lacking muscular control. There are already prototypes of systems that can be applied to a patient with paraplegia to allow him or her to stand and walk. “Bionic” orthotics will incorporate microchips and computer programming to provide a degree of artificial intelligence to devices. This will allow the orthosis to change its setting according to the patient’s input or position during the specific task or part of the gait cycle. In more traditional types of orthotics, the materials used will continue to become lighter, stronger, and more versatile.

No discussion of the delivery of health care services within the United States would be complete or accurate without acknowledging the effects of governmental and private regulations. The earlier discussion regarding a dramatic increase in usage has raised the medical justification debate about the use of orthotic intervention.

Governmental regulations have dramatically changed the course of the orthotic profession, beginning with the Medicare program, to diagnosis-related groups (DRGs), managed care, and, soon, qualified providers. Medicare was the first national program to cover the cost of both orthotic and prosthetic devices. Before that time only a special few had access to “braces and limbs.” DRGs put the responsibility of paying for prescribed orthoses into the hands of the local hospital. Once a specific diagnosis was made, the government would pay a specified amount as reimbursement, leaving the decision of how to manage the patient’s care with the physician and hospital. This policy change created many new innovations. Hospitals, interested in reducing the length of hospital stays, challenged physicians to change the way they treated their patients. Patients are no longer immobilized for long periods in hospital beds and are sent home sooner, or sent to a less acute setting or a skilled nursing facility. The use of orthotic devices to expedite care and for precautionary care during hospitalization has increased dramatically. The use of halo fixation systems, thoracolumbosacral orthoses (TLSOs), fracture orthoses, and contracture-preventing orthoses are a few examples of orthotic care that is helping to reduce length of stay. Another significant effect of the DRG decade on orthotics was the need to reduce delivery times and be as cost-effective as possible. Orthoses needed to be delivered in hours, not days. Careful evaluation developed to determine whether a prefabricated, custom-fit, or custom-made orthosis was most appropriate. A prefabricated orthosis is one that is available in “off-the-shelf ” sizing and is intended for temporary use. Commonly used prefabricated items are commonly kept in stock by the orthotic provider. Custom-fit orthoses are customizable devices that can be modified to optimize the fit to each individual patient. These devices are intended for use on a more definitive basis, and are often appropriate when the patient has adequate sensation and normal anatomy. Custom-made orthoses require very specific measurements or models of the patient to be obtained for the most specific fit and to accommodate any deformity. These devices are time and labor intensive and are worn definitively when the patient’s condition is permanent or when his or her condition or anatomy does not facilitate fitting of a more basic device. Challenges to improve traditional methods of fabrication, better materials, and higher usage spawned the rapid growth of a wide range of orthoses for patient care. There is no reason to believe that this trend will slow as the population ages.

Professional relationships between physical and occupational therapy and orthotics are critical as the evolution of managed care continues. Identifying patient functional goals and a variety of evidence-based care is critical for patient care and clinical outcomes. Orthotic use must be based on proven evidence-based care specific to the profession. In that spirit, a broad overview of the evaluation, prognosis, and intervention of orthotics in neurological rehabilitation is presented.

Basic orthotic functions

Alignment

Alignment of the extremities and spine is a common function in orthotic prescription. The orthosis can provide either temporary or permanent function. A TLSO may be prescribed for stabilizing alignment after spinal fusion in the case of an unstable spinal cord injury (refer to Chapter 16). A supramalleolar orthosis (SMO) is commonly prescribed to hold the foot in proper alignment. When the goal of orthotic intervention is to correct alignment to a position well tolerated by the overlying soft tissue and/or the malalignment is a result of a muscle weakness, the new position should stabilize the joint. Clinicians need to remember that aligning one joint may result in the proximal or distal joint being placed in malalignment. An example of this is a genu valgum knee, which may seem easily corrected. However, changes in alignment result in adjustments by the other joints up and down the kinetic chain. Questions such as “Does the subtalar joint have the mobility to pronate?” must be asked and answered.

Stability

Stability is often required for the patient with neurological deficits. These patients frequently lack the muscle control and strength necessary to maintain trunk balance or to ambulate. Patients with muscular dystrophy benefit from TLSOs to help maintain trunk stability, achieve sitting balance, and perform safer transfers. However, the decision regarding an orthosis must take into consideration maximum stability and flexibility while not restraining breathing capacity. An AFO that limits both dorsiflexion and plantarflexion can stabilize the ankle and the knee for the patient who has had a CVA. Although this patient may initially require medial and lateral ankle stability, controlling the anterior posterior lever arms at the ankle can also provide knee stability and prevent future knee impairments. The orthosis functions in the sagittal plane by producing a posterior force that extends the knee during the stance phase of gait, as most patients requiring this type of stabilization have a foot-flat gait instead of a normal initial heel-strike pattern.

Contracture reduction

Contracture reduction is the goal for many orthotic applications in patients with neurological involvement. The increase in the use of these types of orthoses has been dramatic, as even slight increases in contractures can make the difference between nonambulatory function and ambulatory community participation. Increased awareness and proactive use of prefabricated orthoses have become routine during periods of inactivity, associated surgical procedures, and “sound side” prevention. These types of orthoses can be either dynamic or static and are used in conjunction with various therapeutic modalities to reduce the contracture. Dynamic contracture-reducing orthoses use a spring-type mechanism that applies a low force to a joint over an extended period of time to gain ROM. Static-type orthoses range from serial casts, in which a manual stretch is placed over the joint, to custom-made cylindrical devices designed to spread force over larger areas, to custom-fit devices with some type of quick adjustability. Dynamic-type orthoses are usually contraindicated for the patient with a neurological disorder. Low-tension stretch can trigger spasticity and create skin breakdown because of the high pressure on localized skin areas. The exception for this would be individuals with lower motor neuron impairments and residual hypotonicity. Any tension orthosis needs to be monitored when there is sensory loss, regardless of the cause. To achieve results in contracture reduction, one must be cautiously aggressive, as the amount of force required to improve ROM often threatens the soft tissue’s ability to tolerate the pressure of the orthosis. Experience, frequent sessions, and close communication with other members of the rehabilitation team and the family and patient are critical factors in the success of the use of orthotic devices.

Evaluation

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