Upper Limb Orthoses Health Article

Definition

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.

Purpose

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