Permanent prostheses

There are two primary types of prostheses preparatory and definitive prostheses. The purpose of a preparatory prosthesis (Fig. 33.6) is to allow early ambulation at an efficient and safe level and yet allow for rapid changes in limb volume that often occur in the days and weeks pKjstoperatively. Preparatory prostheses may also include temporary prostheses or permanent prostheses that lack the cosmetic cover. Preparatory prostheses are typically endoskeletal, facilitating the interchange of components as may be necessary before finalizing the limb design. 

The biostable materials such as metals, ceramics, glasses, polymers, and stable composites are intended to stay in a body for the patient s lifetime and function appropriately. They should be physiologically inert, cause only minimal response of the surrounding tissues, and retain their properties for years in vivo. Biostable materials have wide application in permanent prostheses such as joint prostheses, sutures, and other implants. 

Endoprosthesis A permanent prosthesis used wholly within the body, e.g. as a replacement for a bone, a joint, a tendon or a ligament. 

Prosthesis insertion reqnires anesthesia and skilled nrologists. Two prostheses are widely nsed malleahle and inflatahle. MaUeahle prostheses consist of two hendahle rods that are inserted into the corpora cavernosa. The patient appears to have a permanent erection after the procednre the patient is able to bend the penis into position at the time of intercourse. 

Total joint replacements are permanent implants, unhke those used to treat fractures, and the extensive bone and cartilage removed during implantation makes this procedure irreversible. Therefore, when faced with prosthesis failure and the impossibility to reimplant, the patient will face severe shortening of the extremity, instability or total rigidity of the joint, dif culty in ambulation, and often will be confined to a wheel chair. 

The microelectrode array is implanted 10-20 ttm from the retinal surface in a viscous fluid, the vitreous humor [5]. The vitreous is a viscoelastic, gel-like substance that fills the ocular cavity [6]. The experimental setup for characterization of the retinal prosthesis components requires a medium that has the same chemical formulation as the vitreous. Since the early 1900s, different materials have been used as vitreous replacements. These substitutes serve two main purposes. First, they are used to replace a dysfunctional vitreous humor in cases where clouding or physical collapse and liquefaction of the vitreous have occurred. The second is temporary or permanent application during retinal surgery. Since arrays are intended... 

A surgical procedure by which a medical device or prosthesis is placed either temporarily or permanently in the human body. 

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