prosthesis

(prŏs`thĭsĭs): see artificial limbartificial limb,
mechanical replacement for a missing limb. An artificial limb, called a prosthesis, must be light and flexible to permit easy movement, but must also be sufficiently sturdy to support the weight of the body or to manipulate objects.
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Prosthesis

a mechanical device that replaces missing segments of extremities or other parts of the body and compensates for the defect cosmetically and functionally.

There are several types of prostheses. Temporary prostheses, which are used after amputation, are intended for shaping the stump and teaching the patient to walk. Intermediate prostheses, used for therapy and training, are more elaborate and compare in design and biomechanical characteristics with permanent prostheses; they are made from standard semifinished products and can therefore be assembled differently for each individual. Lower-extremity prostheses of this type have a foot and hinges at the ankle and knee. Their length is adjustable, and sockets made of various materials can be joined to them. Definitive (permanent) prostheses are used after the final shaping of the stump.

Prostheses for the upper extremities may replace the hand, forearm, or shoulder or may be fitted following disarticulation of the shoulder; those for the lower extremities may replace the foot, crus, or thigh, or they may be fitted following disarticulation of the thigh. The prostheses are made of standardized semifinished products, and the stump is individually fitted with socket-sleeves. The material used provides a classification for the prosthesis: wood, metal, plastic, or a combination of leather and fabric-reinforced rubber. These prostheses are usually cosmetic and functional (active) prostheses, since they compensate to some extent for the function of the missing extremity. In particular, some types of foot prostheses have been designed with shock absorption and additional lateral movements. There are also crus prostheses without a thigh sleeve that are deeply set onto the lateral condyles of the femur and the kneecap and gently held in place by a harness; these prostheses eliminate undesirable piston-like movements of the stump. Such prostheses compensate for the cosmetic defect.

Among the artificial aids with bioelectric control, the most widely used are forearm prostheses with artificial fingers that flex and extend, allowing the hand to grip and open. Prostheses with bioelectric control have the following advantages: the control system is similar to the natural regulation of movements; the healthy muscles do not have to make unnatural control movements; control is effected without great expenditure of muscle energy; and delicate regulation of finger movements is possible. Forearm prostheses may feature two pairs of movements (gripping and opening of the hand and rotation of the forearm), a feedback device, a multifunctional hand that executes three types of gripping movements using a single actuation mechanism (contraction into a fist, lateral movement, and pinching), or one or three pairs of movements (gripping and opening of the hand, rotation of the forearm, and bending at the elbow hinge).

Bioelectric prostheses are prescribed on an individual basis because of the strict indications and contraindications that govern their use. Prostheses with terminal devices useful in the patient’s occupation are used mostly after amputation of the upper extremities. They are intended to perform tasks corresponding to the patient’s occupational skills. Such prostheses consist of a shoulder or forearm sleeve and, instead of a hand, a special device for holding tools.

Breast prostheses fitted after amputation are made of foam rubber, or they may consist of a shell filled with liquid. They are held in place by a special brassiere. Ocular prostheses compensate for the cosmetic defect created by the removal of an eye. They are made of special types of glass or plastic. An implant prosthesis developed in the 1960’s is sewn to the eye muscles and is thus able to move. Dental prostheses are artificial objects used to compensate for defects in the crowns of teeth or to replace some or all missing teeth. Dental prostheses may be fixed, that is, attached to natural teeth, such as inlays, artificial crowns, or bridges, or removable, such as dental plates and partial dentures. Dental prostheses may also be worn by children to prevent deformation of the face and jaws. Prostheses have also been developed for the nose, ears, and other parts of the face.

N. I. KONDRASHIN and V. G. SANIN

prosthesis

[präs′thē·səs] (medicine) An artificial substitute for a missing part of the body, such as a substitute hand, leg, eye, or denture.

prosthesis

Surgerya. the replacement of a missing bodily part with an artificial substitute b. an artificial part such as a limb, eye, or tooth

See prosthesis

prosthesis

[pros-the´sis] (pl. prosthe´ses) (Gr.) an artificial substitute for a missing part, such as an eye, limb, or tooth, used for functional or cosmetic reasons, or both.Artificial Limb. Advances in the field of surgical amputation and the art of designing artificial limbs have made it possible for persons who have lost a limb to be equipped with a prosthesis that functions so efficiently, and so closely resembles the original in appearance, that they can resume normal activities with the disability passing almost unnoticed.Materials Used in the Prosthesis. A variety of materials can be used for the manufacture of artificial limbs. Wood, especially willow, is the most popular because it is comparatively light and resilient, and is easily shaped. Aluminum or an aluminum alloy is used when lightness is particularly desirable, such as in a limb for an aged person. Plastic limbs are also available. Leather and various metals are used for reinforcement and control.Powering the Limb. Most artificial limbs are powered by the muscles, either those remaining in the residual limb or other available muscles. The muscles of the residual limb often can be considerably strengthened by physical therapy. Muscle power can be reinforced by means of springs, straps, gears, locks, levers, or, in some cases, hydraulic mechanisms.The Artificial Lower Limb. The most commonly fitted artificial limb is the knee-jointed leg, used by persons whose lower limbs have been amputated above the knee. This prosthesis is powered by the hip and remaining thigh muscles, which kick the leg forward. The key points in such a limb are the socket, where it fits onto the residual limb, the knee, and the ankle. The possibility of walking with a normal gait depends primarily on the successful alignment of the socket joint; the knee usually consists of a joint centered slightly behind that of the natural leg, as this has been found to afford greater stability; sometimes the ankle joint is omitted and flexibility of the ankle achieved by the use of a rubber foot.The Artificial Upper Limb. The choice of a particular artificial upper limb depends largely on the person's occupation. There are many different types, ranging from the purely functional, which will enable a person to perform heavy work, to the purely cosmetic, which aims only at looking as natural as possible. Those persons whose work requires them to do heavy lifting are often fitted with a “pegarm,” a short limb without an elbow joint, which is easily controlled and has great leverage.The Artificial Hand. There are many different types of artificial hands. Many artificial upper limbs are so constructed that they can be fitted with a selection of different hands, depending on the type of work to be done. Researchers generally agree that the various types of hooks offer the greatest functional efficiency. These reproduce the most powerful function of natural hands—the pressure between thumb and forefinger. There are also artificial hands that combine a certain amount of utility with cosmetic value, often by means of a cosmetic glove covering a mechanical hand; others are designed simply for appearance, though they may offer some support as well.
Most hooks and hands are mechanically connected to the opposite shoulder and operated by a shrugging motion. However, a procedure known as kineplasty" >kineplasty uses the person's own arm and chest muscles to work the device. In this method, selected muscles are tunneled under by surgery and lined by skin. Pegs adapted to the tunnels can then be made to move an artificial hand mechanism. Kineplasty is used when skill rather than strength is desired.Protecting the Residual Limb (Stump). In a person with an artificial limb, there is always a danger of irritation or infection. A sock is worn to cover the residual limb, and this should be washed daily; the residual limb itself should also be washed regularly and carefully, particularly between skin folds. When the artificial limb is not being used, the residual limb should be exposed to the air if possible.

Types of lower limb prostheses. A, Below-knee endoskeletal prosthesis. The strength is derived from the inner endoskeleton. B, Below-knee exoskeletal prosthesis. The strength is derived from the outer exoskeleton. C, Above-knee endoskeletal prosthesis. D, Above-knee exoskeletal prosthesis. Exoskeletal (E) and endoskeletal (F) hip disarticulation prostheses. From Myers, 1995.Angelchik prosthesis a C-shaped silicone device used in the management of esophagitis" >reflux esophagitis; it can also be placed around the distal esophagus during a laparotomy. (

Placement of the Angelchik antireflux prosthesis. From Ignatavicius and Workman, 2002.)Austin Moore prosthesis a metallic implant used in hip arthroplasty" >arthroplasty.Charnley prosthesis an implant for hip arthroplasty" >arthroplasty consisting of an acetabular cup and a relatively small femoral head component that form a low-friction joint.penile prosthesis see penile prosthesis.

pros·the·sis

, pl.

pros·the·ses

(pros'thē-sis, -sēz; pros-thē'sis), Fabricated substitute used to assist a damaged or replace a missing body part; or to augment or stabilize a hypoplastic structure. [G. an addition]

prosthesis

(prŏs-thē′sĭs)n. pl. prosthe·ses (-sēz) 1. An artificial device used to replace a missing body part, such as a limb, tooth, eye, or heart valve.2. Replacement of a missing body part with such a device.

An artificial body part—e.g., artificial limb, etc.

prosthesis

plural, prostheses Medtalk An artificial body part–eg, pseudobreast, artificial limb, etc. See Bioprosthesis, Heart valve prosthesis, Hemobahn endovascular prosthesis, Neural prosthesis, Seagull wing prosthesis.

pros·the·sis

, pl. prostheses (pros-thē'sis, -sēz) Fabricated substitute for a diseased or missing part of the body. [G. an addition]

prosthesis

Any artificial replacement for a part of the body. Prostheses may be functional or purely cosmetic and may be permanently installed internally or worn externally. The range of prosthetic devices is wide-from artificial eyes and legs to heart valves and testicles.

Prosthesis

A synthetic replacement for a missing part of the body, such as a knee or a hip.Mentioned in: Congenital Amputation, Joint Replacement, Orthopedic Surgery, Peyronie's Disease

pros·the·sis

, pl. prostheses (pros-thē'sis, -sēz) Fabricated substitute used to assist a damaged or replace a missing body part. [G. an addition]

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Synonyms for prosthesis

noun corrective consisting of a replacement for a part of the body

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