One of the most common questions for people considering a shoulder replacement is: “How long will it last?” For people with severe shoulder arthritis, a shoulder replacement can provide predictable pain relief and improvement in quality of life and function. Most studies report that patients are satisfied with a shoulder replacement in about 90% of cases. As a shoulder specialist, I perform approximately 150 shoulder replacements per year and have the opportunity to see this in action. In fact, shoulder replacement is often one of the most satisfying procedures I perform because patients can go from severe daily pain and limited motion to a pain-free shoulder with function and motion nearly equal that of a person not affected with shoulder arthritis.
Shoulder replacement involves resurfacing the humeral head (ball) and the glenoid (socket). For the most part there are few long-term problems with the humeral component. The most common cause of long-term failure of a total shoulder replacement is the socket or glenoid. Several types of glenoid implants are currently in use and many more are in development as surgeons and companies try to refine the glenoid and improve outcomes.
An article published in the December 2013 issue of Journal of Bone and Joint Surgery reviewed the survival of the glenoid component in total shoulder replacement (See Article). The study reviewed nearly 4,000 total shoulder replacements performed between 1976 and 2007. Overall the results were very good with a revision rate (need for repeat surgery) of only 0.8% per year. In other words, about 90% of shoulder replacements are intact 10 years after surgery and about 80% are intact 20 years after surgery. Other studies have found similar results (See Article).
There are a few factors that affect the longevity of shoulder replacements:
Age: Taking age into consideration most patients over the age of 65 can safely assume that a single shoulder replacement will last the rest of their life. On the other hand, younger patients may not be able to expect this. Younger patients place higher demands on their shoulder replacement and “wear out” the prosthesis earlier.
Design of the implants: These survival results are encouraging but closer examination also shows that the results may vary by the type of implant used. The difference in these type of components is in the backside shape (or portion of the plastic cemented in the bone) which is either a keel shape or 3-4 pegs. With the keel there is one slot for the glenoid that is created and the component is cemented. The advantage is ease of preparation and insertion. But, this type of fixation has less rotational strength since there is only one piece in the bone and failure of any portion of the cement may lead to failure of the entire component.
Another 2013 review from Journal of Bone Joint Surgery reported that survival of the glenoid was improved with a pegged component compared to a keeled component (See Article). They found that for every 23 to 115 shoulder replacements (the number varies based on the confidence interval) a revision could be avoided by using a pegged component over a keeled component. While the difference is not great, for the patient this could obviously be very important! For these reasons I use a pegged component during my total shoulder replacements. For a surgeon who performs shoulder replacement routinely, a pegged component does not take more time but may lead to better long-term outcomes.
How the implant attaches to the bone: Another approach to the glenoid is to use a component that is not cemented into place. These types of components rely on bone ingrowth with the native glenoid. The technique is appealing because it avoid cement which may preserve bone stock and decrease surgery time (not having to wait for the cement to harden). However, the results thus far are inferior compared to cemented components. The Australian Joint Registry for instance has demonstrated that revision with a cementless glenoid is 10-14% at 3 years after surgery compared to only 3% with a cemented glenoid.
In summary, several factors affect the survival of a total shoulder replacement. Overall, the survival is 90% at 10 years. However, the survival is lower in younger patients and may be affected by the surgeon and the design of the implant. Patients undergoing shoulder replacement may want to discuss these factors with their surgeon in order to improve the chances of an excellent long-term outcome.