Options for Limb Prostheses

There are 5 general types of upper extremity prosthesis:

• Passive prostheses

• Body-powered prostheses

• Externally powered myoelectric prostheses

• Hybrid prostheses

• Activity-specific prostheses

Passive prostheses assist in balance, stabilization of objects (such as paper when writing), or recreational/vocational activities. They look like a natural limb, are the lightest and cheapest, but they provide no active hand prehension.

Body-powered prostheses are the most often prescribed because they tend to be less expensive, more durable, and require less maintenance. A harness-cable system suspends the prosthesis and captures scapular and humeral motion to operate the hook, hand, or elbow joint. Some systems use the opposing arm to trigger one particular function; one end of a strap encircles the opposite arm at the axilla, and the other end connects to a cable that controls the terminal device (hook, hand, or specialty device for particular function). People involved in physical labor typically favor this type.

Externally powered myoelectric prostheses provide active hand and joint movement without the need of scapular, humeral, or trunk motion. Sensors and other inputs detect muscle movement of the residual limb or upper body and control powered actuators that provide greater grasp force than body-powered prostheses.

Hybrid prostheses are typically prescribed for higher level upper-limb amputations. They combine specific features of body power and myoelectric power, for example a body-powered elbow might be combined with an externally powered hand or terminal device.

Activity-specific prostheses are designed to allow participation in activities that would otherwise damage the patient's residual limb or everyday prosthesis, or when the everyday prosthesis would not function effectively. These prostheses often include a specialty design interface, socket, suspension system, and terminal device. Activity-specific terminal devices can allow the patient to grasp a hammer and other tools, a golf club, or baseball bat, or hold a baseball glove. Others aid in various specific activities (eg, swimming, fishing). These devices can be passive or controlled by the amputee.