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How a knee replacement is done

What happens during a knee replacement

If you're having a knee replacement, you'll usually go into hospital on the day of the operation.

Just before the operation, a nurse will take you to the operating theatre.

You'll either have a general anaesthetic (you're asleep during the operation) or a local anaesthetic in your spine (you're awake but will have no feeling from the waist down).

The operation usually takes about 1 to 2 hours. The type of surgery you have depends on things like how damaged your knee is, your age and your general health.

Total knee replacement

A total knee replacement is the most common type of knee replacement. This is where the lower end of your thigh bone and the upper end of your shin bone are replaced with metal and plastic parts.

The main steps of a total knee replacement are:

  1. The surgeon makes a cut down the front of your knee and moves your kneecap to the side so they can get to the knee joint behind it.
  2. They cut away the damaged ends of your shin bone and thigh bone.
  3. New parts are fitted over the ends of both bones to create the new joint. The parts are usually made of metal and plastic. Some people may also have the back of the kneecap replaced with a new part.
  4. The kneecap is put back into place.
  5. The surgeon closes the cut on your knee using stitches or clips and covers it with a dressing and bandage.
  6. After the operation, you'll stay in a recovery room until you're fully awake, where you may be given medicines to help with the pain.

Partial knee replacement

A partial knee replacement is used when you have arthritis in one half of your knee. Only the bones on the affected side are replaced with metal or plastic parts.

It's a similar operation to a total knee replacement, but the cut on your knee will be smaller and you should have a quicker recovery.

Video: Knee replacement

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

Media last reviewed: 1 April 2021
Media review due: 1 April 2024

National Joint Registry

After surgery, you'll be asked if you consent to giving your personal details and details of your knee replacement to the National Joint Registry (NJR).

The NJR collects and monitors details of knee replacements to help improve patient safety, experience and outcomes.

Page last reviewed: 9 March 2023
Next review due: 9 March 2026