Introduction 

Knee replacement surgery (arthroplasty) involves replacing a damaged, worn or diseased knee with an artificial joint.

It's a routine operation for knee pain most commonly caused by arthritis.

More than 70,000 knee replacements are carried out in England and Wales each year, and the number is rising. Most people who have a total knee replacement are over 65 years old.

For most people, a replacement knee will last for at least 15 to 20 years, especially if the new knee is cared for properly and not put under too much strain.

Types of surgery

There are two main types of surgery, depending on the condition of the knee:

  • total knee replacement (TKR) – both sides of your knee joint are replaced
  • partial (half) knee replacement (PKR) – only one side of your joint is replaced in a smaller operation with a shorter hospital stay and recovery period

Learn more in how knee replacement surgery is performed.

Why is knee replacement surgery needed?

The most common reason for knee replacement surgery is osteoarthritis. Other conditions that cause knee damage include:

A knee replacement is major surgery, so is normally only recommended if other treatments, such as physiotherapy or steroid injections, haven't helped reduce pain or improve mobility.

You may be offered knee replacement surgery if:

  • you have severe pain, swelling and stiffness in your knee joint and your mobility is reduced
  • your knee pain is so severe that it interferes with your quality of life and sleep
  • everyday tasks, such as shopping or getting out of the bath, are difficult or impossible
  • you cannot work or have a normal social life

Learn more in why knee replacement surgery is used.

Can I have knee replacement surgery?

Adults of any age can be considered for a knee replacement, although it's typically recommended for older people as young, physically active people are more likely to wear the joint out.

The earlier you have a knee replacement, the greater the chance you will eventually need further surgery. However, there is some evidence that replacing the knee joint before it becomes very stiff leads to a better outcome.

Most total knee replacements are carried out on people between the ages of 60 and 80. You will need to be well enough to cope with both a major operation and the rehabilitation afterwards. Read more about getting ready for knee replacement surgery and recovering from knee replacement surgery.

Are there any risks?

Knee replacement surgery is a common operation and most people do not experience complications. However, as with any operation, there are risks as well as benefits.

Complications are rare but can include:

  • stiffness of the knee
  • infection of the wound
  • deep infection of the joint replacement, needing further surgery 
  • unexpected bleeding into the knee joint
  • ligament, artery or nerve damage in the area around the knee joint
  • blood clots or deep vein thrombosis (DVT)
  • persistent pain the in the knee

In some cases, the new knee joint may not be completely stable and further surgery may be needed to correct it.

Read more about the risks of knee replacement surgery.




Knee replacement: an animation

This animation shows how knee replacement surgery is done and explains why it would be needed.

Media last reviewed: 22/11/2013

Next review due: 22/11/2015

Having an operation

If your GP has suggested you may need surgery, this guide is for you

Page last reviewed: 16/06/2014

Next review due: 16/06/2016