According to the American Academy of Orthopaedic Surgeons, about 12.3 million people visited a physician in 2002 for treatment of a shoulder problem.

Excessive or repetitive motion, sudden twisting or trauma can damage the structures in the shoulder joint and cause pain, stiffness, inflammation and limitation of movement. Athletes and those who regularly perform overhead motions are at higher risk of shoulder problems.

Three bones come together to make the shoulder - the collarbone (clavicle), shoulder blade (scapula) and the upper arm bone (humerus). There are actually two joints within the shoulder. The end of the shoulder blade and the collarbone meet to form the acromioclavicular (AC) joint. The glenohumeral joint connects the rounded ball at the top of the arm bone with a socket in the shoulder blade. Muscles, tendons (tough cords of tissue that connect muscle to bone) and ligaments (tissue that connects bones) provide stability and support for the shoulder.

Another problem that can affect the shoulder is arthritis. Osteoarthritis is an degenerative disease caused by "wear and tear" on the joint. The condition leads to the destruction of the joint's protective cartilage (the outer covering that prevents bones from rubbing together during movement). Rheumatoid arthritis is an inflammation of the lining in the joint (normally, the lining produces a fluid that helps to lubricate the joint). Posttraumatic arthritis is a type of osteoarthritis that develops after trauma or injury to a joint.

Shoulder Replacement

Sometimes shoulder pain can be treated with medications, physical therapy and exercises. When these treatments fail, a physician may recommend a shoulder replacement - removal of all or a part of the shoulder joint and replacement with an artificial joint.

Shoulder replacement can be a tricky procedure. The shoulder joint is not as easily accessed as the hip or knee joint. Surgeons must take great care to avoid damage to blood vessels or other structures in the joint. Fit is also sometimes a problem because it's hard to predetermine the precise size need of the prosthesis.

Surgeons now have another option for shoulder replacement, called the PROMOS(tm) Shoulder System. The shoulder system consists of four modular components. The stem that fits inside the bone. The body is an adjustable section that is attached to the top of the stem. The neck is a section that connects the body to the last section (the head, or rounded "ball top" that replaces the end of the bone). The joint socket is a standard polyethylene socket.

To place the implant, the surgeon removes the old joint and matches the size of the head with that of one in the PROMOS system. The stem is placed into the upper arm bone. Next, the adjustable body is placed on top of the stem. If the stem is too short, a longer body can be attached to adjust for the size difference. That enables the surgeon to get a more precise fit with the artificial joint. The system is held securely in place without the need for surgical cement. If necessary, doctors can repair other damaged structures in the joint (such as the rotator cuff).

After surgery, patients spend about three months in a rehabilitation program to build up strength and range of motion. Most patients see improvement within a week or two of surgery. The typical PROMOS patient is an active person over 60. Outcome is usually so good many patients request the surgery be performed on the opposite shoulder. However, doctors advise waiting three months before having the second surgery to make sure they are functioning well with the initial replacement.

The PROMOS shoulder system received 510(k) marketing approval from the FDA in January 2004 and expects to have the device fully available this month. For information or referral to a surgeon, visit the company's website at http://www.plusortho.com/.

SOURCES

National Institute of Arthritis and Musculoskeletal and Skin Disease, http://www.niams.nih.gov