All of us have a friend or relative that has had a total knee replacement for total hip replacement, but it is far less common to know a person that has had a total shoulder replacement. Although there are about 23,000 total shoulder replacements done every year, both total knee replacements and total hip replacements are 20 times more common. Arthritic conditions of the shoulder can be every bit as disabling as arthritis in the hip and knee. When the ball and socket joint of the shoulder loses its joint surface in arthritis, the shoulder becomes painful with movement and the movement becomes quite restricted. Conservative measures including medication, physical therapy, injection and activity modification can be very effective and may extend the life of the joint for many years. When these measures are no longer are effective replacement of part or all of the shoulder joint may be the best option.
There are a number of options that we have available for treatment of arthritis by joint replacement of the gleno-humeral, that is ball and socket, joint. Depending on the areas of damage, age of the patient, cause of the arthritis, and status of the rotator cuff, different types of replacement would be considered.
The most conservative and least invasive type of shoulder replacement is a resurfacing of the ball. In this procedure the humeral head joint surface is shaved down to the underlying bone and a metal cap of the same anatomic size is placed over this shaved surface. This can provide a smooth round surface that can provide good relief of shoulder pain and restoration of range of motion as long as the socket joint surface is still in good shape and the rotator cuff is intact. This can especially be useful in younger active patients who are limited by severe pain. In order for this procedure to be done the humeral head has to be round and have good quality bone. This allows the bone to grow firmly into the porous undersurface of the replacement. Good bone ingrowth will last many years.
If the humeral head is too deformed or the quality of the bone is not adequate, a shoulder hemi- arthroplasty can be performed. In this procedure, the humeral head is removed with a saw and completely replaced with a new metal humeral head of the same size and shape. The head is fixed to the bone with a stem that goes down the center of the humeral bone. The bone the surrounding the stem grows into the stem providing very strong fixation. Since the new ball is completely replaced with metal, this type of prosthesis can be used even with severely deformed or weak cystic bone. This will provide very good pain relief and excellent function of the shoulder as long as the socket joint surface is in good shape and the rotator cuff is intact. In some circumstances, and arthritic socket could be cleaned and shaved down when the hemi-arthroplasty is placed. This is called a “ream and run” procedure. This could be used in a younger patient that has severe arthritis and is not quite ready for a total shoulder replacement. It is thought that the socket could be replaced later if the shoulder becomes painful in the future. The amount of pain relief that a patient receives following this procedure may not be as good as a total shoulder replacement.
When the arthritis in the shoulder is severe, affecting both sides of the joint, excellent pain relief can be achieved by replacing both the ball and the socket. This is called a total shoulder replacement. In addition to replacing the ball with the ball and stem, a new socket, or glenoid component is placed. This procedure provides the best pain relief and function for people with severe arthritis and a functioning, intact rotator cuff. The drawback to this procedure is that the glenoid replacement has a limited life span. Recent studies show 93% well fixed at 10 years and 85% still well fixed at 20 years after surgery. This is the best option for people over 60 and many people in their 50’s. The potential for loosening becomes a greater concern for the younger patient with severe arthritis. New types of glenoid replacement are being developed and look promising in the early stages.