Rotator Cuff Arthropathy and the Reverse Shoulder Replacement
Arthritis caused by a large rotator cuff tear.
Pain and loss of active motion about the shoulder.
Physical therapy and occasional cortisone injections.
Arthroscopic debridement cartilage debris removal of the shoulder in patients with good range of motion and a reverse shoulder replacement in patients with pain and limited range of motion.
A sling for a few days after the debridement and for 3 weeks after the reverse shoulder replacement.
The rotator cuff’s main function is to keep the humeral head centered on the glenoid. Its secondary function is to rotate the humeral head view.
Figure 1 shows how the subscapularis contracts and pulls the humerus down, preventing it from riding high when the deltoid elevates the arm; Figure 2 shows how the supraspinatus contracts and pulls the humeral head into the glenoid socket, preventing the humerus from riding high when the deltoid elevates the arm; Figure 3 shows how the posterior two rotator cuff muscles contract and keep the humerus down and centered on the glenoid, while the powerful deltoid elevates the arm.)
When the rotator cuff is significantly torn, the humeral head will sit high with respect to the glenoid and lead to arthritis. The deltoid causes the humeral head to rise on the glenoid. Figure 4, which depicts the deltoid, a powerful muscle that elevates and abducts the arm; Figure 5 shows an MRI where the rotator cuff is torn causing proximal migration. The supraspinatus is outlined in red and should be attached to the greater tuberosity. The yellow line shows the upward force applied to the humerus by the deltoid and the pink shows the elevation of the humeral head with respect to the glenoid.
Rotator cuff arthropathy is a very difficult problem for any doctor to treat. It is considered an unsolved problem in the young patient who is under 65 years of age. Patients usually present with pain and difficulty lifting their arms. Many of the patients have had rotator cuff repairs that failed and re-tore.
Because rotator cuff tears are essentially the only problem about the shoulder that can lead to such a difficult problem to fix, most shoulder surgeons recommend surgery to fix tears when they occur in young active patients. It is better to go through a rotator cuff repair with its accompanying 90% success rate in returning the patient to normal function and minimal to no pain, than to watch the shoulder worsen over time to become a painful crippled extremity.
In young patients who have massive tears that are scarred and retracted and unfixable, there are options but none are extraordinarily appetizing. Living with the shoulder is recommended for the patients who have unfixable tears and little to no pain. These patients likely have enough of the other three rotator cuff muscles still functioning that they can compensate for the unfixable torn one.
Occasionally, cortisone injections can take a painful weak arm and turn it into a painless weak arm that can be observed.
A muscle transfer such as the latissimus dorsi transfer is an option for the young patient with pain and weakness but no arthritis on x-rays. This surgery transfers a normal muscle to replace the irretrievable muscle. Since this procedure is performed infrequently, it is best performed at an academic center where the surgeon may perform a few annually opposed to the community where the surgeon may perform one every few years.
Other options in the young patient with an irreparable rotator cuff tear include a superior capsular reconstruction, arthroscopic debridement, and partial shoulder replacement surgery.
Many times patients with unfixable rotator cuff tears will have entrapments of the suprascapular nerve and releasing the nerve can offer these patients pain relief. Patients who have pain with palpation of the infraspinatus and supraspinatus (the two muscles innervated by the suprascapular nerve) or patients who have EMG (a nerve test) evidence of suprascapular entrapment are considered candidates for a nerve release.
For the patient with a massive unfixable painful rotator cuff tear who can not lift their arm (a condition called pseudo paralysis), options are particularly limited. This scenario is called rotator cuff arthropathy when it is accompanied by proximal migration of the humerus with respect to the glenoid. Arthritis is a component as the articular cartilage on the humeral head wears away as the humeral head rubs against the acromion above. Partial shoulder replacements (called humeral head replacements) may alleviate some of the pain but they do not improve the function of the shoulder. The only weapon in our armamentarium that can minimize pain and improve function is a reverse shoulder replacement, which is a wonderful option for the patient over the age of 65. These replacements are so new to shoulder surgery that many surgeons are not sure if they will last more than 15-20 years, which does not make them great options in the younger population where there still is not an answer for rotator cuff arthropathy.
Once the humerus has migrated superiorly, it is difficult for the deltoid to remain under tension and to lift the arm. Thus, people with rotator cuff arthropathy (rotator cuff tears and arthritis) will have pain, stiffness, crunching, and weakness with an inability to lift their arm. View Figure 6 & 7a. The reverse shoulder replacement pushes the humerus down. The restoration of the proper position of the humerus puts the deltoid under tension. The pain is relieved by the fact that the bones are no longer rubbing against each other, now replaced by metal rubbing against plastic. Function is improved by the fact that the deltoid is under tension and can now elevate the arm. View Figure 7b, 8 & 9.
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