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Unicompartmental knee replacement

6-minute read

What is arthritis?

Arthritis is a group of conditions that cause damage to one or more joints.

The most common type of arthritis is osteoarthritis, where there is gradual wear and tear of a joint.

Arthritis eventually wears away the normal cartilage covering the surface of the joint and the bone underneath becomes damaged. This causes pain and stiffness in your knee, which can interfere with normal activities. If only part of your knee is damaged by arthritis, you can sometimes have a partial knee replacement instead of a total knee replacement.

What are the benefits of surgery?

You should get less pain and be able to walk more easily. A partial knee replacement may bend better and feel more like a normal knee than a total knee replacement.

Are there any alternatives to a partial knee replacement?

Simple painkillers such as paracetamol and anti-inflammatory painkillers such as ibuprofen can help control the pain of arthritis.

Using a walking stick on the opposite side to the affected knee can make walking easier. Wearing an elasticated support on your knee can help it feel stronger.

Physiotherapy may help to strengthen weak muscles.

A steroid injection into your knee joint can sometimes reduce pain and stiffness for several months.

An operation called a tibial osteotomy changes the shape of your leg and can take the load off the worn part of your knee.

If you decide not to have a partial knee replacement, you can usually have a total knee replacement instead.

Illustration of a unicompartmental knee replacement.
A unicompartmental knee replacement.

What does the operation involve?

Various anaesthetic techniques are possible. The operation usually takes an hour to 90 minutes.

Your surgeon will make a cut on the front of your knee and will check that your knee is suitable for a partial replacement.

Your surgeon will remove the damaged joint surfaces. They will then insert an artificial knee joint made of metal, plastic or ceramic, or a combination of these materials.

The implant is fixed to the bone using acrylic cement or special coatings on your knee replacement that bond directly to the bone.

How can I prepare myself for the operation?

If you smoke, stopping smoking now may reduce your risk of developing complications and will improve your long-term health.

Try to maintain a healthy weight. You have a higher risk of developing complications if you are overweight.

Regular exercise should help to prepare you for the operation, help you to recover and improve your long-term health. Before you start exercising, ask the healthcare team or your GP for advice.

Speak to the healthcare team about any vaccinations you might need to reduce your risk of serious illness while you recover. When you come into hospital, practise hand washing and wear a face covering when asked.

What complications can happen?

Some complications can be serious and can even cause death (risk: 1 in 1,000).

General complications of any operation

  • bleeding
  • infection of the surgical site (wound)
  • allergic reaction to the equipment, materials or medication
  • acute kidney injury
  • difficulty passing urine
  • blood clot in your leg
  • blood clot in your lung
  • chest infection
  • heart attack
  • stroke

Specific complications of this operation

  • damage to nerves around your knee
  • damage to blood vessels behind your knee
  • bearing dislocation, where the piece of plastic in the middle of your knee replacement comes out of place
  • infection in your knee
  • wear or loosening
  • continued discomfort in your knee
  • severe pain, stiffness and loss of use of your knee

Consequences of this procedure

  • pain
  • unsightly scarring of your skin

How soon will I recover?

You can go home when your pain is under control, you can get about safely, and any care you may need has been arranged.

You will need to use walking aids until you can walk well without them.

Regular exercise should help you to return to normal activities as soon as possible. Before you start exercising, ask the healthcare team or your GP for advice.

Most people make a good recovery, have less pain, and can move about better. An artificial knee never feels quite the same as a normal knee.

A partial knee replacement can wear out with time.

Summary

Arthritis of your knee usually happens without a known cause. It can sometimes affect only part of your knee. If you have severe pain, stiffness and disability, a partial knee replacement should reduce your pain and help you to walk more easily.

IMPORTANT INFORMATION

The operation and treatment information on this page is published under license by Healthdirect Australia from EIDO Healthcare Australia and is protected by copyright laws. Other than for your personal, non-commercial use, you may not copy, print out, download or otherwise reproduce any of the information. The information should not replace advice that your relevant health professional would give you. Medical Illustration Copyright © Medical-Artist.com.

For more on how this information was prepared, click here.

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Last reviewed: September 2023


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