If you’re thinking about knee replacement for the first time, one of the first questions you’ll be asking yourself is: how long will the implant last?
We all know that any new technology has a shelf life. Cars wear out. Computers slow down. Smartphones need upgrading. But artificial implants for knees are, naturally, in a different category of importance. So it’s reasonable to ask how long we can expect them to work well before they need replacing.
The short answer
The very short summary is that most people can expect their knee replacement to last around 15 to 20 years. To put that in statistical terms, there’s a 95% chance your implant will last 10 years. And a roughly 80% chance it will last 20 years. These stats are based on the newer generation of implants. And they’re very similar for both total and partial knee replacements.
The longer answer
The longer answer is that your implant could potentially have a higher survival rate than 15 or 20 years (“survival rate” is the term doctors use to describe your implant’s length of life before it needs replacing). Since the newer implants are themselves less than 20 years old, the statistics only go back so far. But the evidence from older devices suggests they could last even longer. Meta-analysis has shown that the 25-year survival rate for TKR (total knee replacements) is 82.3% and for partial 72%, for example.
Why it’s hard to be precise
That said, it’s impossible to make cast-iron guarantees about knee replacements. Why? One reason is that they aren’t just dependent on the implant itself, but on some important patient factors too. These include things like:
Activity levels – high-impact activities like running and jumping raise the risk of wear and failure
BMI – being overweight puts much more pressure on your joints – artificial ones included
Prehab + rehab – being consistent with your knee exercises can have a big impact on the overall outcome
(For more on exercise and knee replacements, see Can you run after a knee replacement? and 3 common exercises for knee replacement patients)
Why it’s an important question to consider
If you actively want to have a knee replacement, is there really any point thinking about how long your implant will last? We’d say there definitely is. That’s because revision surgery – replacing an artificial joint when it breaks, becomes loose, wears out or gets infected – is a more complicated undertaking than the original operation. For instance:
Process – revision surgery involves careful pre-op planning, different tools and specialist skills
Biology – bone that has grown into the old implant needs to be removed before the revision
Recovery – the recovery period generally takes longer than for new knee replacements
Longevity – revision knee replacements generally don’t last as long as initial implants
Put simply, revision surgery is something to avoid if you can. That’s one reason why consultants often advise younger patients not to plunge into a first knee replacement. If you have a replacement at 40, you’re quite likely to need another one in the future – even if your implant lasts you two or three decades.
The good news
With all that said, it’s worth remembering that knee replacement is generally a very common operation (there are around 100,000 every year in the UK) with excellent success rates. Though it takes time and patience to go through the operation, most people feel the quality-of-life improvements that follow make it worth the effort.
It’s also worth bearing in mind that knee replacement is getting better all the time. Implants today are lighter, stronger and more natural than the ones surgeons were using 30, 40 or 50 years ago. Surgical skills and techniques are more sophisticated than ever. While no operation comes with a 100% guarantee, your knee replacement has a very good chance of lasting for years to come.
