Reverse Total Shoulder Replacement
The Reverse Shoulder Replacement is a special type of replacement that relieves pain and restores function for very specific shoulder problems. It only received FDA approval in 2003, which means that the American experience with the implant is still maturing. It is one of the more exciting advances in modern shoulder surgery as it offers a solution to some previously untreatable problems.
Reverse shoulder replacement in many respects is like conventional shoulder replacement with regard to hospital stay, early postoperative pain management and sling wear. There are multiple distinctions however, and you should be aware of them if you are contemplating having this surgery.
The reasons to perform reverse shoulder replacement differ from conventional shoulder replacement
When rotator cuff tears occur in conjunction with arthritis, a condition called rotator cuff arthropathy, you’ve got a double whammy that a conventional replacement can’t fix. The problem with the conventional replacement is that it only works well when your rotator cuff works well.
When the cuff tendons are not working, the ball of your shoulder does not stay centered well in the socket. With every upward motion of your shoulder, the ball tends to slide up and abut the undersurface of your shoulder blade.
Over time that constant upward motion can create abnormal rocking motions at the surface of a conventional socket replacement and lead to early failure. Past experience along these lines led surgeons to abandon the conventional implant for this condition. And it took many years before a reliable design came to the forefront to overcome this limitation.
In general the best reason to perform reverse total shoulder replacement, is for rotator cuff arthropathy. But recently it has been found to be a good solution for other problems including: certain fractures in elderly adults, failed total shoulder replacement, certain irreparable rotator cuff tears, and unique complex reconstructions.
The design differs from conventional shoulder replacement
The name gives it away: “reverse total shoulder.” Literally the surgeon places a ball shaped component on your socket and a socket shaped component where the ball once lived: the opposite of anatomical shoulder replacement. The reversal of the position of the ball and socket is what gives the implant its name.
Another difference is that the metal ball is secured into the socket with screws not cement like the conventional shoulder replacement socket.
A metal stem is inserted into the humerus much like the conventional shoulder replacement.
Some very involved biomechanics principles dictate why it is done this way.
In short, when you lose your rotator cuff muscles, you also lose certain restraining forces within the shoulder. The cuff muscle normally acts to keep the humerus from riding up and bumping against the undersurface of the shoulder blade. When the rotator cuff muscles are absent, the large deltoid muscle contracts and pull the shaft of the humerus up with nothing to counteract it.
Reversing the component positions keeps the humerus from riding above the socket as the deltoid muscle pulls. The center of rotation of the joint changes as well. This gives the deltoid muscle a torque advantage that it would otherwise not enjoy. Again some sophisticated biomechanics are at play.
The bottom line is that the reverse replacement allows for shoulder elevation without the presence of rotator cuff muscles. In essence the implant is working around the loss of the rotator cuff and forcing your body to work some shoulder muscles in different ways.
Your results may vary
New studies continue to show that the results that you will obtain from reverse total shoulder replacement vary depending on the reason you had the operation.
I mentioned above that there are many reasons for which a reverse shoulder replacement might be a good option for you. It turns out that patients with rotator cuff arthropathy tend to do best after this procedure.
Other conditions such as fracture, revision surgery and conversion from hemiarthroplasty to reverse shoulder replacement still tend to improve significantly compared to the before the operation, but perhaps not as much as those with rotator cuff arthropathy.
It’s comparing apples to oranges really. And if the reverse shoulder is the best option for your, then it’s the best option for you.
However, this information can guide your expectations, and help you cope with the fact that other people may have better or worse results depending on their particular condition.
Additionally you should not expect that this implant would function exactly like a normal shoulder. It is considered a “salvage” prosthesis: one used when there is no other good solution. So your expectations for strength and function should remain somewhat guarded.
Remember that the operation first and foremost is meant to reduce pain. Range of motion and strength should be a secondary goal. Usually the functional gains are quite good comparatively speaking, but they are not quite as predictable as we would like.
Rehabilitation is different from conventional shoulder replacement
While you will do some physical therapy after a reverse total shoulder replacement, it is not nearly as extensive as if you had a anatomic total shoulder replacement. This is because stiffness is not usually as much of a problem in reverse total shoulder replacement as it can be with anatomic total shoulder replacement. Therefore many of the early range of motion exercises that are done for other shoulder surgeries are not necessary after reverse total shoulder replacement.
I typically keep patients in a sling for the first six weeks after surgery doing little more than elbow, wrist and hand range of motion. I make sure to counsel patients to avoid reaching behind their back with the operative arm in the first 6 weeks after surgery, as this is the riskiest position for potential dislocation. The odds of dislocation go down after this initial time period.
After six weeks I have patients start a gentle range of motion and strengthening program that may be self directed depending on the needs and desires of each patient.
Are there unique risks to the reverse shoulder replacement?
While many of the risks of the procedure like anesthesia and potential for infection are similar to anatomic shoulder replacement, there are some unique risks to the procedure. As surgical experience with the implant has grown over the past 10 years, the complication rates have fallen significantly.
The risk of instability may be higher in reverse shoulder replacement. The strict sling protocol with no shoulder movement behind the back that I use has served me well and produced a virtually nonexistent rate of instability.
There is little risk of rotator cuff rupture. This is simply because the rotator cuff is absent or inconsequential in many cases of reverse total shoulder replacement.
There are not many options after a reverse total shoulder replacement. Once you have one in, you cannot go back to an anatomic shoulder replacement. This is a unique risk to the operation. In chess terminology, you are in check. This is why we try to choose the potential candidates for this procedure wisely. The reverse shoulder replacement is usually best suited for older patients for this reason.
Dr. DiPaola is one of a small percentage of orthopedic surgeons in the country that performs shoulder replacement regularly. He performs dozens each year and is skilled with performing reverse total shoulder replacement, a new and technically challenging procedure. If you are considering shoulder replacement please contact us for more information or a personal consultation.