Shoulder joint replacement surgery is the answer for many adults with painful arthritis. This operation to replace the ball and socket is called total shoulder arthroplasty (TSA). Sometimes only half of the joint needs to be replaced. This is called a hemiarthroplasty. Many studies show that shoulder joint replacement can help relieve pain and improve function.
Doctors at The Cleveland Clinic Foundation agree with these findings. They also looked at four factors that might affect the success of the operation. First, does a tear of a muscle or tendon around the joint mean problems later on? Second, how does bone thinning affect the joint implant? Third, does a loss of shoulder joint motion before surgery make any difference afterwards? Finally, if the joint moves out of the socket, will this affect the TSA?
On the basis of 128 shoulder TSAs, the authors made some comments. Loss of motion before replacement surgery is only a risk factor if the person can’t rotate the arm out very far (external rotation). Motion is better after TSA when moderate to severe bone thinning and damage is present before the operation. This is because smoothing the joint surfaces makes it easier for the joint to move.
Tears to the muscles or tendons around the joint (called the rotator cuff) don’t seem to make a difference. The implant works just as well whether the tear is repaired or left alone. However, a shoulder joint that moves out of place before the surgery is more likely to be unstable afterwards.
The authors note that when any of these factors is present, a total joint implant is needed. Simply replacing half the joint (hemiarthroplasty) may not be enough.