REVERSE SHOULDER REPLACEMENT

By Gerald W. Rothacker, Jr., M.D.

Most everyone knows someone who has had a total knee or hip replacement. Some may be surprised to learn that there is also a total shoulder replacement.

This operation has been done for almost as many years as total knee and hip replacements, about forty years!

The indication for a total shoulder replacement is true shoulder joint arthritis which is rare compared to knee or hip joint arthritis.

Standard total shoulder replacement follows all of the concepts of other joint replacements, replacing the worn bony ball with a metal ball, and the worn shoulder blade side of the articulation (glenoid) with a plastic surface.

The success of total shoulder replacement is as good as total hip or knee replacement if the rotator cuff is intact and working. It offers relief of pain and a functional range of motion.

There is a type of shoulder arthritis that was a challenge to treat and a frustration for both orthopedic surgeon and patient. This was the arthritis of the shoulder associated with a chronic tear of the rotator cuff, “rotator cuff arthropathy”.

With this type of arthritis, the mechanics of the shoulder is lost because of the absence of the rotator cuff muscles and tendons. The patient has not only the damage and pain of shoulder arthritis, but also the loss of motion associated with a tear of the rotator cuff tendons.

A standard total shoulder replacement in this setting occasionally relieves the pain but rarely restores functional motion. Three years ago the FDA approved a modification of the total shoulder replacement called the “reverse total shoulder replacement”.

What is reversed is the ball and the “socket”.

The ball is placed on the shoulder blade. This is normally the socket but really is hardly more concaved than a teaspoon. The rotator cuff muscles and tendons are necessary to keep the ball opposed to this surface and allow for range of motion.

The socket of a reverse total shoulder replacement is a true socket and is placed on the humerus, the arm bone.

This switch of ball and socket allows the deltoid muscle (the muscle that gives the roundness to the shoulder) to function as both the power of the shoulder but also the controller of rotation of the shoulder.

This design now offers a solution to the chronic pain and loss of function brought about by long term rotator cuff tear of the shoulder.

The recovery is long, four to six months. Active motion of the shoulder is restricted for the first four to six weeks, to allow the muscles detached while doing the reverse shoulder replacement time to adequately heal back to the bone. Physical therapy with the therapist doing all of the work restoring passive motion begins a week from surgery and continues for several months with patient progressively doing more of the exercise. The expectation is for comfort and a “functional” range of motion allowing one to get the hand to the head and face.