We just came back from the orthopedic surgeon’s office where my husband was told he is a good candidate for a reverse shoulder replacement. The surgeon did mention the various problems that can develop (like they do with any surgery). But he also talked about implant “failure.” I’m not sure I understand what that means. Can you explain it?

Shoulder replacement or arthroplasty is not unusual anymore. Regular replacements of the ball and socket joint are often done for people with painful and limited range of motion. But the standard shoulder replacement isn’t the best choice for everyone. Some patients need the reverse shoulder arthroplasty (RSA) you mentioned. This is mostly used for people who have injuries of the rotator cuff and shoulder arthritis that leave the shoulder unstable.

The rotator cuff is a group of four muscles that wrap around the shoulder to hold it in the socket. They also help move the shoulder. RSA is an option when the rotator cuff is no longer strong enough or functioning well enough to hold the shoulder in the socket. The RSA provides pain relief as well as a stable functioning shoulder.

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. As you heard, 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.

Failure is the word surgeons use when the patient has to have a second surgery to fix something about the implant. This next procedure is referred to as a revision surgery. Revision surgery may be needed when some part of the implant comes loose or breaks or the bone graft used around the implant is resorbed (broken down and absorbed) by the body. Bone loss around the implant can cause it to sink down into the bone (called subsidence).

Implant failure can happen but reports so far are that the majority of patients (96 per cent) have a good result that lasts a minimum of six years. More studies are being done to follow patients for longer periods of time and will report problems, failures, and results. In the meantime, don’t hesitate to ask your surgeon how often he or she does this procedure and what his or her “success” rate is with these surgeries. (It’s probably better to ask about the success rate than to ask about his or her “failure” rate).

The majority of patients who have this surgery are pleased with the results. They have less pain, more motion, and greater function. Overall, there are few complications and many, many more successes than failures.