Under the skin of the 25-year knee implant
Jim Newman looks at the ramifications of the recent study by the University of Bristol, which suggests most knee replacements now last 25 years.
It’s rare that orthopaedic research becomes breakout, mainstream news. But the recent study by the University of Bristol did just that – and for good reason, because it found that most hip and knee replacements now last 25 years.
This was a vast survey of 500,000 patients over a 25 year period. So the resulting report is a) something worth taking very seriously and b) unequivocally good news for anyone who’s had a knee replacement in the past few years, and anyone who suspects they’ll need one soon.
Why is this such good news?
One of the reasons some surgeons have (to date) shied away from operating on younger patients is because of concerns that their joint replacement may wear out early and they’ll need revision (redo) surgery. As a consequence, many younger patients are being denied surgery that could hugely improve their quality of life and ability to work. This recent study backs up my long-held view that age should not necessarily be a block to something that could have a massively positive impact on a patient’s life.
Even if the replacement joints don’t last as long as you might hope because, for example, your job places a heavy load through your knees, the fact is that if you need mobility now to be able to continue working, a replacement in 15 years won’t help very much.
So the news that most replacements last 25 years is good news because it relieves some of the tension in determining when is the right time to have a knee replacement operation. The report should give encouragement to anyone of any age who feels they may need a knee replacement operation. But in a strange way, not a great deal has actually changed.
Patient by patient
Whilst this data is very good news, it’s important to remain thoughtful and consider other options before diving into a joint replacement. Firstly, there are no guarantees the new joint will last 25 years. As a knee replacement wears, it’s not only the implant that deteriorates; it wears the bone too. If you’ve had a partial knee replacement, the chances are that next time you will need a total replacement. If you’ve already had a total knee replacement, the degree of bone loss associated with the redo surgery can be significantly greater. This means the operative risks can increase and the function and pain relief can be less predictable. So the longer you can avoid a knee replacement the better. Secondly, as a younger patient, there’s also an increased likelihood that you’ll place more demands on the knee, increasing the rate of wear and the risk of requiring redo surgery.
So we need to be a little circumspect. If you lead a highly active life. If your work is demanding on the knees. If you are a little on the heavier side, your knee implant may not last as long as you hope.
That shouldn’t stop us operating on younger patients. But nor should it lead to shortcuts in the journey from early diagnosis of osteoarthritis to a knee replacement. We still need to consider what happens if the implant doesn’t last. We still need to consider the risks associated with surgery. And perhaps most importantly, we still need to hold honest conversations with patients so we get beyond the 25 year headline to explore what a knee replacement is likely to mean for them.