Shoulder replacement or arthroplasty is not unusual anymore. Regular replacements of the ball and socket joint are often done for patients with painful and limited range of motion. But the standard shoulder replacement isn’t the best choice for some people. Some patients need a reverse shoulder arthroplasty (RSA). This is mostly used for people who have injuries of the rotator cuff and shoulder arthritis that leave the shoulder unstable.
Reverse replacements put the ball of the joint just off the shoulder blade with the socket off the upper arm. This placement is different from the usual ball at the top of the humerus (upper arm bone) and the socket on the shoulder blade.
The reverse shoulder joint isn’t a perfect solution. It comes with problems of its own. For example, some patients end up with pain, loss of motion, and a problem called impingement. Impingement results in an inability to put the arm all the way down at the side. The implant design, location, and angle result in the two parts of the implant bumping up against each other, preventing full motion.
When reverse shoulder replacements were first introduced, the glenosphere was placed in the middle of the glenoid (anatomic shoulder socket). But problems developed and surgeons recognized the benefit of changing their surgical technique to avoid those complications. Despite changes made, impingement was still a problem.
So, new implant designs and surgical techniques are the subject of ongoing studies. Some surgeons may wish to wait until the procedure is applicable to more patients. When a surgeon only does a handful of any procedure, the results may not be as good as for the surgeon who performs dozens or even hundreds. Referring to a surgeon who specializes in reverse shoulder replacements makes good sense.