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 the joint, which can interfere with normal activities. If only part of your knee is damaged by arthritis, you can sometimes have a unicompartmental knee replacement instead of a total knee replacement.

Figure 1 - A unicompartmental knee replacement

What Are the Benefits of Surgery?

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

Are There Any Alternatives to a 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.

The Procedure

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 unicompartmental replacement. Your surgeon will remove the damaged joint surfaces. They will replace these with an artificial knee joint made of metal, plastic or ceramic, or a combination of these materials. Your knee replacement is fixed to the bone using acrylic cement or special coatings on your knee replacement that bond directly to the bone.

What Complications Can Happen?

Some of these can be serious and can even cause death.

General Complications of Any Operation

  • Pain
  • Bleeding
  • Infection of the surgical site (wound)
  • Unsightly scarring of your skin
  • 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
  • Loosening
  • Severe pain, stiffness and loss of use of your knee
Surgeon in face mask

Following Surgery

How Soon Will I Recover?

You should be able to go home after 1 to 4 days. You may need to use a walking aid for a few weeks. 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 unicompartmental knee replacement can wear out with time.


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 unicompartmental knee replacement should reduce your pain and help you to walk more easily.

For more information on a Private Knee Replacement procedure, call New Victoria Hospital on 020 8949 9020 or use our contact form


Author: Mr Stephen Milner DM FRCS (Tr. & Orth.)
Illustrator: Medical Illustration Copyright ©Medical-Artist.com


This page is intended for information purposes only and should not replace advice that your relevant healthcare team would give you.


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Mr Khalid Al-Dadah

MBChB, MRCS (Ed), PGCert, FHEA, FRCS (Tr&Orth)
Orthopaedics, Knee Surgery
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Mr Richard Hampton

MB BS(Lond) FRCS(Eng) FRCS(Tr&Orth)
Orthopaedics, Hip & Knee Surgery
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Mr Giles Heilpern

MA(Hons) MB BS(Hons) FRCSEd(Tr and Orth)
Orthopaedics, Knee & Shoulder Surgery
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