By W. Preston Blake, M.D.
In my 30-year career as an orthopaedic surgeon, total joint replacements have become one of the greatest innovations I have observed. Taking an individual whose lifestyle is severely compromised by his or her arthritic joint and improving his or her function by replacing the joint is very gratifying. One of the joints that can be replaced when it becomes severely arthritic is the shoulder, and that is what I would like to discuss today.
Before we discuss the actual replacement, it is important to understand the special characteristics of the shoulder and the challenge of designing a shoulder joint replacement. The shoulder has a greater range of motion than any other joint. It is a ball and socket joint like the hip, but the shoulder socket is very shallow. As a result, the ball (humerus bone) is not as securely held by the socket (glenoid) and a deeper layer of muscles, called the rotator cuff, helps hold the ball in alignment with the socket.
Over our lifetime, the rotator cuff tendons become worn and lose their ability to keep the humerus centered on the glenoid. As a result, the ball is not held in proper alignment with the socket, and the joint wears out – becoming arthritic. This leads to a special type of shoulder arthritis called rotator cuff arthropathy, which requires a specially designed shoulder replacement called a reverse prosthesis. Therefore, there are two types of total shoulder replacements: a conventional prosthesis, which is used when the rotator cuff is functioning well, and a reverse prosthesis, used when the rotator cuff is severely worn and functioning poorly.
If you are having pain in your shoulder and upper arm, a very common cause is "wear and tear" of your rotator cuff. This can be made worse by a superimposed injury. This is not treated with joint replacement, but an appropriate combination of therapy, injections and possible surgery, if appropriate. However, if your doctor finds that the cause of your pain is an arthritic joint and it is severe enough for surgery, then conventional or reverse arthroplasty can be considered. Usually, the X-ray shows us which prosthesis is appropriate though sometimes MRI or CT scans can provide additional information, which helps the surgeon plan your operation. The operation takes one to two hours, and most patients remain in the hospital for one to two days.
Physical therapy following shoulder joint replacement varies according to the preferences of the surgeon and parameters that the surgeon determines at the conclusion of the procedure. I generally keep people in a sling for three to four weeks and have them perform exercises that will not disrupt the healing tissues but allows some progression of range of motion of the joint. Most people are using their arm for simple tasks and self care by six weeks after surgery. As the shoulder gains motion and strength, function can continue to improve for as long as two years, but most of the improvement is gained by six months.
How much improvement is obtained varies from person to person. Like total knee replacements, the major challenge is maximizing motion and strength. There is significant pain relief, but occasional soreness can persist. People with fairly healthy rotator cuffs have the most successful recovery, but significant improvement in pain and function is common even with the most damaged rotator cuffs.
Patients often ask me which prosthesis brand I will use when I replace their hip, knee or shoulder. I first tell them that many companies make excellent products and successful joint replacement results can be achieved with many different brands. I recommend that patients choose a surgeon who they are comfortable with and confident in and allow that surgeon to use whichever approach and prosthesis the surgeon has had good results with.
Shoulder joint replacement is not the "new kid" on the block but significant improvements have occurred in recent years. In my opinion, shoulder joint replacements offer the same expectations for improvement as do total hip and knee replacements.