The shoulder joint is really made up of two Joints: The AC Joint and the Glenohumeral Joint. The AC joint is so named because the Acromion and the Clavicle touch together here. The Acromion is part of the shoulder blade. The AC joint can and does become arthritic. Spurs develop underneath the AC joint and these spurs can agitate the tendons of the rotator cuff. The rotator cuff tendons rub back and forth underneath the AC joint when the shoulder moves. The arthritic spurs of the AC joint can impinge on the rotator cuff tendon during shoulder motion. The resultant rotator cuff tendonitis is the most common cause of shoulder pain in adults over 40.
The Glenohumeral Joint (GHJ) is the main "ball and socket" part of the Shoulder. Arthritis of the ball and socket (GHJ) part of the shoulder is a less common affliction than AC joint arthritis. Many patients with mild to moderate degrees of (GHJ) arthritis can be treated with medications, activity modification and physical therapy or home based exercises. The purpose of these exercises is to that tone the rotator cuff muscles. When toned these muscles can help reduce the amount of rubbing in the GHJ. It is when the GHJ arthritis progresses to the severe stage that these techniques tend to no longer be adequate and total shoulder replacement (TSR) surgery is considered. Since patients do not need to walk on the shoulder joint, severely symptomatic shoulder arthritis comes late in the disease progression. As a result, most patients who seek treatment for severely symptomatic shoulder arthritis are already at the stage when TSR is the only treatment to afford dramatic relief.
Total Shoulder Replacement has a high success rate in reducing or eliminating shoulder arthritis pain. In general the operation is easier to navigate for the patient when compared to Total Hip or Total Knee replacement surgery since the Shoulder is a non-weight bearing joint. The operation is however requires a one to two day hospital stay and some postoperative physical therapy. A return to near normal function requires a well functioning rotator cuff. Much of the post operative treatment is directed to the strengthening of the rotator cuff muscles which often atrophy during the period of worsening arthritis. Since a functioning and intact rotator cuff is essential for traditional TSR surgery to be successful, the joint replacement specialist may need to do additional preoperative tests (MRI scan) to check the patient’s rotator cuff condition.
A special version of TSR is available for the patient with shoulder joint arthritis who does NOT have a functioning rotator cuff. This operation is called Reverse Shoulder Replacement. The operation reverses the polarity of the ball and socket of the shoulder thus explaining the name. This novel technique allows for pain reduction in the rotator cuff deficient patient but it does not restore the function of the rotator cuff itself. Patients without an intact rotator cuff are usually unable to elevate their arm much above the waist.