Revision Knee replacements

What is it?

A revision knee replacement is a surgical procedure to remove some or all of a prosthetic knee that has failed and replace it with a new one. Artificial knee joints are state-of-the-art prostheses made from metal and hard plastic. Although they are designed to be very hard-wearing – and most total knee replacements last at least 15 years – nevertheless they do eventually wear out and will need to be replaced.

In some cases, an artificial knee joint may fail far sooner, however. The implant may become loose, causing instability and pain in the knee. While the precise reasons for this are not always clear, in some cases high impact activities or being overweight can be a factor. In younger patients who are more physically active, there can be a greater risk of implant loosening than in older people with a more sedentary lifestyle.

In some cases, an infection can develop in the prosthetic knee implant itself. This may occur in the hospital immediately after your knee replacement surgery, or when you go home or even many years afterwards. Infection can cause the artificial joint to become stiff and painful and it may start to loosen. You may notice swelling and drainage from the affected joint.

You may also develop stiffness in your artificial knee if too much scar tissue builds up around the joint.

Who might need it?

You might need a revision knee replacement if you have previously undergone a knee replacement and the implant has started to fail, leading to pain, stiffness, swelling or instability in the knee joint.

What to expect

A revision knee replacement takes longer than a primary knee replacement – several hours in some cases. The surgeon will follow the same incision as your primary knee replacement and move aside your kneecap and tendons. After checking for signs of infection, they will identify which parts of the implant have become worn or loose. They may then remove some or all the original implant and the cement used to fix it in place. Once the implant is removed and the bone surfaces are prepared, the revision implant will be fitted. The surgeon may need to fit specially designed components to compensate for any bone loss that has occurred.

If you have an infection: If you have developed an infection in your artificial knee, the treatment will depend on the type of bacteria, how long you have had the infection and how serious it is. In some cases, it can be treated with antibiotics but if these are insufficient you may need one of the following:

• Debridement – This involves washing the bacteria out of the implant and replacing the plastic spacer. The metal components are left in situ.
• Revision replacement – This is normally done in two stages. In the first stage, the implant is removed and the joint is washed out to remove the bacteria. A temporary cement spacer is placed in the knee. It is treated with antibiotics to kill the bacteria. The spacer remains in your knee joint for several weeks and at the same time you will receive intravenous antibiotics. Once the infection has gone, the surgeon carries out the second stage surgery, to remove the temporary spacer and replace it with a new prosthetic knee joint.

If you have a build-up of scar tissue: If you have knee stiffness due to a build-up of scar tissue you may be offered a surgical manipulation procedure under anaesthetic. While you are asleep, the surgeon will bend and straighten your knee to break up scar tissue and improve your range of motion. In many cases, this is successful but if there is extensive scar tissue or the position of the components of your implant are preventing your knee from moving properly, you may subsequently need to have revision knee replacement surgery.

If you have a periprosthetic fracture: A fracture that occurs around the artificial knee joint is called a periprosthetic fracture. They are often caused by a fall and can result in the loosening of the prosthetic knee as well as bone damage. Depending on the condition of the remaining bone and whether it is affected by osteoporosis, you may need a larger revision implant to compensate for lost bone.

After surgery, you will be taken to the recovery room where you will be carefully monitored as you come round from the anaesthetic. Once discharged from hospital you will need to follow an exercise programme recommended by the physiotherapist.

Benefits of revision knee replacement surgery

Revision knee replacement surgery helps to correct any problems that have developed with your artificial knee. In most cases, it successfully relieves pain and increases stability. However, a revision replacement does not generally achieve such good results as primary knee replacement surgery. In some cases, you may still experience a certain amount of pain and knee stiffness after the procedure.