A decade ago, people with a torn rotator cuff and severe arthritis in the shoulder were beyond surgical treatment, and had no choice but to live with the pain. However, in 2004 the Federal Drug Administration approved the use of the reverse total shoulder replacement, which gives these patients a chance at pain-free use of the affected arm.
“The reverse shoulder replacement is designed specifically for use in shoulders that have a deficient rotator cuff and arthritis or complex fractures, as well as other difficult shoulder reconstructions,” says Brent Ponce, MD, assistant professor of orthopaedic surgery at UAB, and one of only two fellowship trained shoulder surgeons in Alabama. “It is sometimes a very useful option for revision of a failed prior joint replacement where the rotator cuff tendons are chronically torn and cannot be repaired.”
In an arthritic shoulder, cartilage is worn away, resulting in bone-on-bone contact, instead of the normal smooth gliding surfaces. The joint may also become irregular, and motion can be limited further by osteophytes, which are uneven bony growths around a joint. “Pain is usually due to the irregular joint surfaces rubbing on one another and from the inflammation to the joint capsule from this wear and tear,” Ponce says.
In the case of certain types of arthritis, called cuff arthropathy, there can also be a loss of the rotator cuff tendons that encircle the humeral head (ball) and help to elevate and keep the humeral head in the glenoid (socket) when the arm is raised. These tendons also help to internally and externally rotate the humerus on the glenoid.
“Without normal function of the rotator cuff, the humeral head may move upward to the top part of the glenoid socket making it difficult or impossible to raise the arm,” Ponce says. “If a conventional joint replacement is used in this situation, the socket of the implant is prone to loosening because of abnormal forces across the replacement due to the absent rotator cuff. There may be some initial pain relief, but the humeral head eventually migrates upward leading to a loosening of the glenoid component of the replacement, pain and reduced function of the arm.”
The reverse shoulder replacement changes the orientation of the shoulder so that the normal socket (glenoid) is replaced with an artificial ball, and the normal ball (humeral head) is replaced with an implant that has a socket into which the artificial ball rests. “This type of design completely changes the mechanics of the shoulder and enables the artificial joint to function when the rotator cuff is absent,” Ponce says. “Because the joint is constrained like the hip joint, it becomes more stable than it would be following a conventional shoulder replacement.”
Typical candidates for this surgery are patients with massive rotator cuff tears, poor function or pseudo paralysis of the arm, and are over 65 years of age. It is not designed for younger patients who need a high level of shoulder functionality or who have high activity demands. “This is a salvage operation,” Ponce says. “It’s what we do when there is no other alternative. These patients, who couldn’t raise their arms before, have an excellent probability to have significant pain relief and to improve their shoulder motion after surgery. It is not unusual for patients to be able to elevate their arm more than 100 degrees following a reverse total shoulder. Pain free is our goal; functionality is secondary.”
While this procedure can provide benefits to patients, Ponce warns that the technique has a complication rate about three times that of conventional shoulder arthroplasty. According to the American Academy of Orthopaedic Surgeons, radiographic and clinical results seem to deteriorate over time, so proper patient selection and attention to technical details are needed to reduce the currently high complication rate.
“We have to make sure we have the right expectations for this patient population. They aren’t patients who will go back to heavy manual labor or high sports activity. They are older patients,” Ponce says. “I will try anything to avoid a reverse shoulder replacement, because once you do it there’s no turning back.”
Ponce recalls performing the procedure on an 89-year-old woman. Because he was reluctant about doing the surgery on someone her age, he consulted with her son and her primary care physician together to make them aware of the risks involved. “She said she was so miserable that she would accept the risks that came with the surgery,” he says. “She did very well, and now she wants the other shoulder done.
