Total shoulder joint replacement surgery (total shoulder arthroplasty) can effectively ease pain from shoulder arthritis. Most patients experience pain relief and improved shoulder function after the shoulder joint replacement surgery. However, certain patients are not candidates for joint replacement of the shoulder because they lack the muscle function necessary to stabilize the joint. A reverse total shoulder replacement works better for these patients, and provides pain relief as well as a stable, functioning shoulder. Specifically, patients with completely torn rotator cuffs with severe arm weakness, rotator cuff tearing, severe arthritis or previously failed shoulder replacement can take advantage of this procedure.
In a healthy shoulder, the rotator cuff muscles help position and power the arm during range of motion. A conventional replacement device also uses the rotator cuff muscles to function properly. In a patient with a large rotator cuff tear and cuff tear arthropathy, these muscles no longer function. The reverse total shoulder replacement allows other muscles, such as the deltoid, to do the work of the damaged rotator cuff tendons. This procedure relies on the deltoid muscle, instead of the rotator cuff, to power and position the arm.
Candidates for Surgery
Reverse total shoulder replacement may be recommended if patients have:
- A completely torn rotator cuff that cannot be repaired
- Cuff tear arthropathy
- A previous shoulder replacement that was unsuccessful
- Severe shoulder pain and difficulty lifting the arm away from the side or over the head
- Tried other treatments, such as rest, medications, cortisone injections, and physical therapy, that have not relieved shoulder pain
For these patients, a conventional total shoulder replacement can still leave them with pain. They may also be unable to lift their arm up past a 90-degree angle. Not being able to lift one’s arm away from the side can be severely debilitating.
Surgical Procedure
The reverse shoulder replacement surgery is performed almost identically to the normal shoulder replacement, except different artificial parts are inserted. This procedure usually takes about two hours to perform.
The orthopedic surgeon will make an incision either on the front or the top of the shoulder. This is called an anterior (deltopectoral) approach. The surgeon removes the damaged bone and then positions the new components (a metal ball that is screwed into the shoulder socket, and a plastic cup that is secured into the upper arm bone) to restore function to the shoulder.
In patients with multiple previous surgeries, a superior approach through the deltoid muscle may be used. The surgeon cuts through the skin and then isolates the nerves and blood vessels and moves them to the side. The muscles are also moved to the side. The surgeon enters the shoulder joint itself by cutting into the joint capsule. This allows the surgeon to see the joint. In more advanced cases of cuff tear arthropathy, and in patients with previous surgery, there may be no capsule and rotator cuff remaining. At this point, the surgeon can prepare the bone for attaching the replacement parts. The ball portion of the humeral head is removed with a bone saw. The hollow inside of the upper humerus is prepared using a rasp. This lets the surgeon mold the space to anchor the metal stem of the humeral component inside the bone.