When it comes to knee replacement surgery, how old should you be?
This may sound like an odd question. If you’re ready to have a knee replacement then, by definition, you’re old enough to have one… aren’t you?
Actually, it’s a little bit more complicated than that. But it’s a great question to ask. Indeed, it’s one we get quite regularly from patients in their 40s, 50s, 60s, and younger. Let’s look at the detail.
What do we mean by “young”?
It’s useful to start by looking at who’s actually having knee replacements right now. Here’s a breakdown for England and Wales in 2021 from the NJR (an organisation we profiled in this recent article: What can the National Joint Registry tell you about knee replacements?).
The headline statistic here is that the average age of a patient having a knee replacement is 68 or 69. So if you’re 67 then, well, you’re already on the younger side.
How many people under 68 are having knee replacements?
This graph* from the NHS offers a good answer to that. You can see that while the age range of knee replacement patients peaks in the mid to late 70s, it falls quite dramatically for people 60 and under. In their 40s, very few people are having the operation at all.
Why is it so rare for younger patients to have them?
The main reason is because it raises the chances of needing a repeat procedure in the future – an operation known as revision surgery. Like all things in life, artificial knees eventually wear out. The average lifetime of a modern implant is very good – about 15-20 years, and potentially much longer – but in time it may need to be replaced. And of course the younger and more active you are, the greater the likely wear-and-tear. The problem with revision surgery is that it’s a significantly more complex undertaking than the initial operation. There’s a longer recovery period and there are greater potential risks (for more about this, see How long does a knee replacement last?). So for younger people, especially, the benefits of having a new knee need to be carefully weighed against the potential complications when that implant deteriorates. That’s why doctors typically ask younger patients to wait for longer, if they can.
So when is the right time for a knee replacement?
The simple answer, in almost all cases, is that knee replacements are for people who are suffering severe symptoms (such as pain, swelling, inflammation and instability) caused by bone-on-bone arthritis. This type of knee damage is sometimes referred to as “end-stage knee osteoarthritis”. And it basically means the protective cartilage in the joints has worn away completely, leaving the bone surfaces to rub painfully against each other. Everyday activities become very difficult, and the overall impact on quality of life is pretty severe. For true “bone-on-bone arthritis” cases like this, patient satisfaction with the outcome of a knee replacement tends to be very high (while, conversely, satisfaction rates are lower if knee replacement is used to treat milder arthritis). Ultimately, age is still a crucial factor to weigh up when considering whether to have the operation – and this is something you’ll need to talk through in detail with your consultant. But for those cases where severe arthritis is making life unbearable, knee replacement can be a game changer.