A replacement for missing body parts

In medicine, a prosthesis is an artificial extension that replaces a missing part of the body. Contrasted with orthosis which supplements the body. Prostheses are typically used to replace parts lost by injury (traumatic) or missing from birth (congenital) or to supplement a defective body part; such as, a tooth, eye, a facial bone, the palate, a hip, a knee or another joint, the leg, an arm, etc. A prosthesis is designed for functional or cosmetic reasons or both.

A prosthesis may be removable, as in the case of most prosthetic legs or a prosthetic breast form used after mastectomy. A person who uses a removable prosthesis; for example, an artificial hand, may want to have more than one available for different types of tasks. Other kinds of prosthetic devices are permanently implanted, like an artificial hip, testicle, or tooth.

With advances in the biomedical sciences, a few experimental prostheses have been integrated with body tissues, including the nervous system. These highly advanced devices can respond to commands from the central nervous system, more closely approximating normal movement and utility.

An auditory prosthesis is a device that substitutes for or enhances the ability to hear. It is more commonly called a hearing aid.

The word "prosthesis" comes via New Latin from the Greek prostithenai meaning "to add to, or to put in addition (to)".

The prostheses unit of words.