How to tell if it’s time for a knee replacement


11 March 2013

Having a damaged knee replaced can improve your quality of life dramatically. When you’re weighing up whether now is the right time, talking it through with your doctor should come top of your to-do list. 

Knee replacement surgery is a common operation and over 84,000 of these operations took place in England, Wales and Northern Ireland in 2011.

The positive message to take from this statistic is that thousands of people will have benefited from reduced pain and increased mobility as a result of their surgery.

“The most common cause behind knee replacement surgery is osteoarthritis, where the surface cartilage has worn away and there may be exposed bone,” says Howard Ware, Director of the Wellington knee surgery unit, The Wellington Hospital, London.

“Occasionally inflammatory arthritis, like rheumatoid disease, can be the cause of the problem, but the drugs are so good at treating this condition now that we see less of these.”

Most people needing a knee replacement because of osteoarthritis will be older – it is much more common over the age of 60.

In a younger group – the young middle-aged patient – the cause is usually related to sporting injuries and because they’ve needed surgery in the past to remove cartilage or repair ligaments.

More women than men have knee replacement operations, although the reason behind this isn’t clear. 


Is there anything you can do to avoid having a knee replacement?

“There are some simple things you can do, like losing weight,” says Mr Ware. “There is a correlation – if you’re significantly obese then your knee will wear faster. If you lose weight you might find it’s less painful.

“Exercising your quadriceps muscles – those that run from your knee, up the front of your legs, almost to your hips – can sometimes reduce the discomfort around the knee.”

Avoid impact sports if your knees are showing signs of injury. You can also ask your doctor whether it’s worth having steroid injections in the knee, as these can sometimes help.

If you have been struggling with discomfort in a knee joint, how do you tell if it’s time to have a replacement?

“One word – pain, that’s the best indication,” says Mr Ware. “It doesn’t matter really if your knee is a bit deformed or stiff, most people will accept that and wouldn’t have their knee replaced.

“It’s quality of life pain, where it’s agony, or you can’t sleep because of it. That’s easy, then we know they need a replacement.”

Certainly if you have constant pain at rest, sitting or sleeping, or can’t walk for more than five to ten minutes without stopping, then it’s probably time for a discussion with your doctor.
If only part of your knee has deteriorated, you may be able to have a partial knee replacement, which is a smaller operation.

“The advantage of a partial knee replacement is that it’s then much easier to proceed at a later stage to a full knee replacement if needed,” says Dr Alasdair Wright, GP and Musculoskeletal Practitioner. “However, not everyone is suitable for a partial knee replacement – particularly if you have advanced osteoarthritis through the knee, or your knee is unstable due to previous ligament damage.”

There’s a good reason for not having a knee replacement carried out until you and your doctor agree that you really need it.

If you have it carried out when you’re quite young, or too early, the replacement knee will be used more, and you’re more at risk of having a second, or even a third replacement.

“If you’re 45 and your knee is very arthritic and you can’t walk, it’s nonsense to say to someone ‘wait until you’re older’,” says Mr Ware. “If you’re young and you can cope we’d say ‘well, hang on a while, because it will wear faster now than when you’re a bit older’.

“The replacement knee is a metal and plastic joint and it’s the plastic that’s the weak link – it will wear over time. When you’re younger you’re likely to be more active and use the knee more, which will wear down the plastic.
“The second replacement is a bigger operation, technically harder, and has more risk of infection,” says Mr Ware. “And it may not give you the movement and the satisfaction that you’d like.”


Operation risks

All operations involve some risk, and a knee replacement is no different. Fit, healthy people are less at risk than those who are older and in poorer health.

The standard risks include heart attack, stroke, thrombosis and a clot on the lung, but they aren’t high.

“Most people have high blood pressure, but as long as it’s well-controlled, it’s not a risk,” says Mr Ware.

“The same goes for diabetes. Probably the most common problem we see is people with heart problems. If they are on blood-thinning agents like warfarin, they may need an up-to-date cardiac opinion before the knee replacement goes ahead. And they will have to stop taking the blood-thinning agents during the surgical period.”

Weighing up whether you want to go ahead with a knee replacement should involve a discussion with your specialist, looking at all the factors in your situation. For most healthy people the risks aren’t high.

For more information on maintaining your knee joint health, visit our Musculoskeletal Centre and read our facts sheets on knee replacement and arthritis.