ARTHRITIS OF THE SHOULDER
The shoulder joint is composed of three bones—the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone). Two joints facilitate shoulder movement. The acromioclavicular (AC) joint is between the acromion (part of the scapula that forms the highest point of the shoulder) and the clavicle. The glenohumeral joint, commonly called the shoulder joint, is a ball-and-socket type joint that helps move the shoulder forward and backwards and allows the arm to rotate circularly or hinge out and away from the body. (The ball is the top, rounded portion of the upper arm bone or humerus; the socket or glenoid is a dish-shaped part of the outer edge of the scapula into which the ball fits.) The capsule is a soft tissue envelope that encircles the glenohumeral joint. A thin, smooth synovial membrane lines it.
The shoulder bones are held in place by muscles, tendons, and ligaments. Tendons are tough cords of tissue that attach the shoulder muscles to bone and assist the forces moving the shoulder. Ligaments attach shoulder bones, providing stability. For example, the front of the joint capsule is anchored by three glenohumeral ligaments.
The rotator cuff is a structure composed of tendons that, with associated muscles, hold the ball at the top of the humerus in the glenoid socket and provide mobility and strength to the shoulder joint. Two sac-like structures called bursae permit smooth gliding between bone, muscle and tendon. They cushion and protect the rotator cuff from the bony arch of the acromion.
ORIGIN AND CAUSES OF SHOULDER PROBLEMS?
The shoulder is the most movable joint in the body. However, it is an unstable joint because of the range of motion allowed. It is easily subject to injury because the upper arm ball is larger than the shoulder socket that holds it. Its muscles, tendons and ligaments must anchor the shoulder to remain stable. Some shoulder problems arise from the disruption of these soft tissues as a result of injury or from—overuse or underuse of the shoulder. Other issues stem from a degenerative process in which tissues break down and no longer function well.
Shoulder pain may be localized or referred to areas around the shoulder or down the arm. Disease within the body (such as gallbladder, liver, heart disease, or disease of the cervical spine of the neck) may also generate pain that travels along nerves to the shoulder.
WHAT IS ARTHRITIS OF THE SHOULDER?
Arthritis is a degenerative disease caused by either wear and tear (osteoarthritis) or inflammation (rheumatoid arthritis) of one or more joints. Arthritis not only affects joints; it may secondarily affect supporting structures such as muscles, tendons and ligaments.
SIGNS AND DIAGNOSIS
The usual signs of arthritis of the shoulder are pain, particularly over the AC joint, and a decrease in shoulder motion. A doctor may suspect the patient has arthritis when there is pain and swelling in the joint. A physical examination and X-rays may confirm the diagnosis. Blood tests may help diagnose rheumatoid arthritis, but other tests may also be needed. Analysis of synovial fluid from the shoulder joint may help diagnose some kinds of arthritis. Although arthroscopy permits direct visualization of damage to cartilage, tendons and ligaments and may confirm a diagnosis, it is usually only done if a repair procedure is to be performed.
TREATMENT
Most often, shoulder osteoarthritis is treated with nonsteroidal anti-inflammatory drugs, such as aspirin or ibuprofen. (Rheumatoid arthritis of the shoulder may require physical therapy and additional medicine, such as corticosteroids.) When conservative treatment of osteoarthritis of the shoulder fails to relieve pain or improve function, or when there is severe deterioration of the joint causing parts to loosen and move out of place, shoulder joint replacement (arthroplasty) may provide better results. In this operation, a surgeon replaces the shoulder joint with an artificial ball for the humerus and a cap (glenoid) for the scapula. Passive shoulder exercises (where someone else moves the arm to rotate the shoulder joint) are started soon after surgery. Patients begin exercising on their own about 3 to 6 weeks after surgery. Eventually, stretching and strengthening exercises become a significant part of the rehabilitation programme. The operation’s success often depends on the condition of rotator cuff muscles before surgery and the degree to which the patient follows the exercise programme.