Upper Limb Orthoses
An orthosis is a device that is applied to the body in order to protect and stabilize body parts, to prevent or correct scarring and deformities, or to aid in performance of certain functions. Upper limb orthoses are applied to the shoulder, elbow, arm, wrist, or hand. These devices may be called orthoses, orthotic devices, or splints.
Upper limb orthoses can be used for a wide variety of purposes. Some of the more common uses include:
- stabilizing fractures or unstable joints
- immobilizing joints to promote healing
- preventing or correcting joint contractures
- correcting subluxation of joints or improper alignment of tendons
- preventing formation of burn scar tissue
- maintaining correct joint alignment
- assisting movement of joints
- reducing muscle tone in spastic muscles
Materials and construction
Although ready-made orthoses are available for some applications, many are custom made to fit the specific needs of each patient. Orthoses can be constructed of plaster, wood, metal, cloth, or plastic. Since the 1960s, most orthoses have employed lightweight thermoplastic materials, which are plastics that become pliable when they are heated and retain their shape once they cool. They come in sheets of varying thickness, and they can be composed of any of several polymer compounds. The thermoplastic sheets can be molded to fit body parts exactly, and some can be reshaped repeatedly as the treated body part changes shape. The resulting orthotic device is lightweight and relatively easy to use and maintain.
Thermoplastic materials are usually classified into high- and low-temperature types, based on the temperature at which they become pliable. High-temperature thermoplastic materials must be molded at a temperature that is too high to come in contact with human skin. These materials must be molded over a plaster model of the body part, but have the advantage of being stronger and more durable than low-temperature thermoplastics. They are used in situations where the orthosis will under-go a lot of stress or will be used for a long time. High-temperature thermoplastics require special tools for cutting and shaping, and orthoses made from these materials are usually constructed by an orthotist, a technician who specializes in constructing these devices.
Many upper limb orthoses are constructed of low-temperature thermoplastics. This material becomes pliable below 180°F (80°C), and it can be molded directly
against the body. It is relatively easy to cut and shape, and many therapists construct orthoses using these materials. Precut shells made from low-temperature thermoplastics are also available. The therapist can use a precut thermoplastic shell as the base for a device and then modify it to fit by trimming and adding pads and straps. Orthoses made from low-temperature thermoplastics are commonly used in situations in which the orthosis will receive relatively little stress or is intended for temporary use. These orthoses are especially important when a device is needed quickly, such as in postsurgical or trauma treatment.
Both high- and low-temperature orthoses must be attached to the body. Most modern orthoses use straps made of hook-and-loop tape for this purpose. This material is lightweight, durable, and readily adjustable, and it comes in a variety of widths and colors. Orthoses can also include padding to cushion sensitive areas, as well as specialized linings. Patients often use a separate interface that absorbs perspiration and protects the skin, and which can be washed or replaced as needed.
Types of orthoses
The upper limbs comprise a complex system of muscles, joints, ligaments, and tendons, which are capable of a number of distinct movements. For this reason, a wide variety of upper limb orthoses have come into existence. These devices often go by multiple names, reflecting the name of the manufacturer, the name of the person who developed the device, or the anatomy and function it serves. No single naming system has become dominant. Most authors today refer to the devices in terms of anatomy or function rather than using more obscure historical names, but users must be careful to distinguish one device from another.
Orthoses are usually classified as either static or dynamic, depending on the amount of joint movement each device allows. Static orthoses hold a body part in a fixed position and do not allow joint movement. Some static orthoses do not contain joints, as with fracture orthoses that stabilize the long bones of the arm after a fracture. Most others simply maintain the joint at a particular angle, providing support and proper positioning. For example, a static wrist orthosis can be used to hold the wrist in a neutral position to promote healing and
Contracture—An abnormal condition that prevents the full extension or flexion of a joint. Contractures are usually caused by tight or shortened soft tissues around the joint.
Dynamic orthosis—An orthosis that allows or promotes movement of a joint.
Orthotic device—An orthosis.
Orthotist—A technician who specializes in building and fitting orthoses.
Outrigger—A device that is attached to a dynamic orthosis in order to facilitate joint motion. The outrigger serves as a point of attachment for springs, rubber bands, or other energy-storing materials.
Progressive orthosis—An orthosis that can be adjusted to increase the amount of stretch in tissues surrounding a joint. Progressive orthoses are often used to treat joint contractures.
Serial orthoses—A set of orthoses used in a series to gradually increase the range of motion of a joint. Serial orthoses are used to treat joint contractures.
Static orthosis—An orthosis that does not allow movement of a joint.
prevent injury during activities. Sometimes static orthoses include attachments that help patients perform functional activities. For example, a hand-wrist orthosis may include an attachment for pens or eating utensils.
Static orthoses sometimes serve the function of promoting eventual joint movement. Serial or progressive orthoses loosen joints that have become frozen due to contractures or arthritis. Serial orthoses involve several similar devices used in a series, with each successive device gradually increasing the range of motion of the affected joint by providing a gentle stretching action. Progressive orthoses accomplish similar goals, but do so by allowing adjustments in the device so that it gradually increases the amount of stretch created in the joint. Serial and progressive orthoses must be designed and used carefully to provide the correct amount of stretching in the joint. Excessive stretching can damage the tissues, and inadequate stretching will be ineffective.
Dynamic orthoses allow or create joint movement. These devices hold the joint in the proper position while assisting movement using springs, rubber bands, or other mechanical features. Dynamic orthoses are useful for patients who have weakened muscles or limited neuromuscular control, because they allow the patient to perform actions that would be difficult or impossible without assistance. These devices promote independence in patients who have handicapping conditions, and they are common in rehabilitation settings. Since no single device can perform all the movements that the human hand can perform, the patient may need to use several different dynamic devices in order to carry out activities of daily living.
Although there is a wide variety of upper limb orthoses, most of these devices operate on similar principles. The general goal of most orthoses is to provide stability and support while allowing as much motion as possible. Immobilizing joints for long periods has proven deleterious for most patients. Muscles atrophy, joints stiffen, skin tightens, and the healing process is ultimately slowed. By allowing movement while restricting motion that would create stress on joints, muscles, or tendons, orthotic devices allow healing and preserve range of motion and function.
Exact fit is a key element for many upper limb orthoses. In order to work properly, the orthosis must hold the body part in an exact position. If the orthosis does not fit exactly, it may not work and may actually cause harm. This can become a problem in situations where the patient has experienced swelling and may require a new fitting for the orthosis once the swelling has resolved. Poor fit can also lead to discomfort and the development of pressure sores.
Dynamic orthoses usually operate with the aid of attached outriggers. These provide a place to attach rubber bands, springs, or other materials that assist motion. They also provide leverage and help to ensure that the joint stays in proper position during movement. These devices require exact fit, as well as adjustment to ensure that the device works properly.
Many upper limb orthoses require a period of training for the patient to learn how to use the device properly. This is especially true with devices that assist motion, because the patient must initiate the motion properly in order for the orthosis to work. Patients with a long history of paralysis or immobilization may require considerable time in order to learn how to use the device.
It is very important to consider the patient's motivation and attitude toward the orthosis as part of the treatment plan. Since most upper limb orthoses are removable,
Many upper limb orthoses require little or no maintenance. This is especially true for static orthoses and for those intended for temporary use. The plastic shell can be wiped clean, and materials worn underneath the orthosis can be washed or replaced. The patient may need to be checked periodically to ensure that the orthosis fits. Dynamic orthoses may require adjustments and replacement of worn springs, rubber bands, and the like.
Health care team roles
Creating and employing upper limb orthoses often involves a team approach, especially in rehabilitation settings. A physician who specializes in physical medicine and rehabilitation may prescribe the orthosis, which is then built by an orthotist. An occupational therapist or physical therapist may help the patient learn to use the orthosis. In other instances, the physician may refer the patient to an occupational therapist, who then determines that an orthosis would be helpful. Many occupational therapists design and build orthoses themselves, but they may also recommend ready-made devices or refer the patient to an orthotist. Physicians from other disciplines, especially orthopedics, may employ orthoses, as do physical therapists. These professionals may refer the patient for a custom-made device or prescribe a ready-made one.
Health care professionals who create and fit upper limb orthoses must have a good understanding of the anatomy and physiology of the upper limbs. They must also understand the mechanics and forces involved in making various body movements, and they must be familiar with the materials and tools involved in constructing orthoses. Certified orthotists are specialists who focus exclusively on fitting and building orthoses. Certification as an orthotist requires a baccalaureate degree in the field of orthotics and prosthetics, or a degree in another field followed by a six-month to one-year certificate training program. Orthotists must also pass a certification exam.
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American Academy of Orthotists and Prosthetists. 526 King St., Ste. 201, Alexandria, VA 22314. (703) 836-0788. <http://www.oandp.org>.
National Rehabilitation Information Center. 1010 Wayne Ave., Ste. 800, Silver Spring, MD 20910. (800) 346-2742. <http://www.naric.com>.
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Denise L. Schmutte, Ph.D.