02/21/11 9:29am

This is the second of a two-part column on shoulder pain.

Both forms of arthritis ­— osteoarthritis and rotator cuff tear arthropathy — can cause the disabling symptoms of shoulder pain and limited motion of the shoulder, but the type of shoulder replacement needed will differ depending on the type of arthritis present.

In osteoarthritis resulting from wear and tear, the soft tissues surrounding the shoulder, including the rotator cuff, are generally in good shape and provide a stable soft tissue envelope for the shoulder. A normally functioning rotator cuff adds stability to the shoulder joint, keeping the ball centered on the socket. In these cases, a conventional total shoulder replacement, one that replaces both the ball and the socket of the shoulder but has the same shape as the native shoulder, can be used.

However, in the case of rotator cuff tear arthropathy, the soft tissue envelope around the shoulder is inadequate, leading to instability of the ball on the socket. In this case, the deficient rotator cuff is unable to keep the ball centered on the socket, and the ball moves up and forward on the socket. If a conventional shoulder replacement is used in this setting, it will generally fail early. Therefore, a reverse shoulder arthroplasty can be used instead to add stability to the unstable shoulder joint. As its name implies, a reverse shoulder arthroplasty switches the location of the ball and socket relative to the native shoulder. It places the ball on the end of the shoulder blade and the socket at the top of the arm bone and greatly increases the stability of the unstable shoulder joint. The procedure was developed in France about 25 years ago and has been performed in the United States since 2001, gaining FDA approval in 2005. The procedure offers a reliable treatment option for patients who have often been told nothing can be done for their dysfunctional shoulders.

Each of these shoulder replacement options can dramatically reduce the pain of shoulder arthritis and improve a patient’s range of motion. Patients with osteoarthritis treated with a conventional total shoulder replacement generally see a return in their range of motion that approaches what they had prior to having shoulder problems in the first place. These shoulder replacements have a longevity and patient satisfaction similar to total hip and knee replacement surgeries. Those patients with shoulder dysfunction from rotator cuff tear arthropathy treated with a reverse shoulder replacement note similar pain relief to patients treated with a standard total shoulder arthroplasty. The ultimate range of motion achieved after a reverse replacement generally is slightly less than that obtained after a conventional total shoulder arthroplasty, but these patients generally start with a much more limited range of motion as well. In fact, cuff tear arthropathy is often associated with a clinical entity called the “pseudoparalytic” shoulder, a condition characterized by such limited shoulder range of motion that patients are unable to elevate their arm at all. The life expectancy of reverse shoulder replacements is still being resolved, but studies show that almost 95 percent of patients treated with this procedure still have their implants in place at nine years out from the surgery.

Dr. Matthew Walker practices with Long Island Bone and Joint, with offices in Riverhead and Southampton.