Type of Surgery
Information
Last updated: 11/24/2009
Shoulder joint replacement surgery can either replace the entire AC joint, in which case it is referred to as total shoulder joint replacement or total shoulder arthroplasty; or replace only the head of the humerus, in which case the procedure...
is called a hemiarthroplasty.
Implants
The two artificial components that can be implanted in the shoulder during shoulder joint replacment surgery are:
- The humeral component. This part replaces the head of the humerus. It is usually made of cobalt or chromium-based alloys and has a rounded ball attached to a stem that can be inserted into the bone. It comes in various sizes and may consist of a single piece or a modular unit.
- The glenoid component. This component replaces the glenoid cavity. It is made of very high-density polyethelene. Some models feature a metal tray, but the 100% polyethylene type is more common.
Shoulder joint replacement surgery is performed under either regional or general anesthesia, depending on the specifics of the case. The surgeon makes a 3–4 in (7.6–10.2 cm) incision on the front of the shoulder from the collarbone to the point where the shoulder muscle (deltoid) attaches to the humerus. The surgeon also inspects the muscles to see if any are damaged. He or she then proceeds to dislocate the humerus from the socket-like glenoid cavity to expose the head of the humerus. Only the portion of the head covered with articular cartilage is removed. The center cavity of the humerus (humeral shaft) is then cleaned and enlarged with reamers of gradually increasing size to create a cavity matching the shape of the implant stem. The top end of the bone is smoothed so that the stem can be inserted flush with the bone surface.
If the glenoid cavity of the AC joint is not damaged and the surrounding muscles are intact, the surgeon does not replace it, thus performing a simple hemiarthroplasty. However, if the glenoid cavity is damaged or diseased, the surgeon moves the humerus to the back and implants the artificial glenoid component as well. The surgeon prepares the surface by removing the cartilage and equalizes the glenoid bone to match the implant. Protrusions on the polyethylene glenoid implant are then fitted into holes drilled in the bone surface. Once a precise fit is achieved, the implant is cemented into position. The humerus, with its new implanted artificial head, is replaced in the glenoid socket. The surgeon reattaches the supporting tendons and closes the incision.
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Knee joints or finger joints are fairly easy to understand--they facilitate back and forth movement; however, anywhere that two bones meet in the body there is some sort of joint. This animation describes the different joints in the body and what anatomical structures make up joints.
During a total shoulder joint replacement, an incision is first made in the shoulder and upper arm (A). The head of the humerus is removed with a bone saw (B). The shaft of the humerus is reamed with a bone rasp to ready it for the prosthesis (C). After the shoulder joint, or glenoid cavity, is similarly prepared, bone cement is applied to areas to receive prostheses (D). The ball and socket prostheses are put in place, and the incision is closed (E). (Illustration by GGS Inc.)
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Definition
Shoulder joint replacement surgery is performed to replace a shoulder joint with artificial components (prostheses) when the joint is severely damaged by such degenerative joint diseases as arthritis, or in complex cases of upper arm bone fracture.
Purpose
The shoulder is a ball-and-socket joint that allows the arms to be raised, twisted, bent, and moved forward, to the side and backward. The head of the upper arm bone (humerus) is the ball, and a circular cavity (glenoid) in the shoulder blade (scapula) is the socket. A soft-tissue rim (labrum) surrounds and deepens the socket. The head of the humerus is also covered with a smooth, tough tissue (articular cartilage); and the joint, also called the acromioclavicular (AC) joint, has a thin inner lining (synovium) that facilitates movement while surrounding muscles and tendons provide stability and support.
From http://www.answers.com/topic/shoulder-joint-replacement
Other Information
New procedures like minimally invasive procedures are often subject to scrutiny, but I think that one of the biggest problems facing these innovative procedures is for people to understand exactly what we do.
-Dr. Michael Perry, Laser Spine institute
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