Knee joint replacement

What is a knee replacement?

A knee replacement is an operation which involves replacing the worn out parts of an arthritic knee with an artificial joint.

Knee replacements can either take the form of a total knee replacement (TKR) or a partial (unicomparmental) knee replacement. Total knee joint replacement is the most common type of knee replacement undertaken.

A knee replacement is a good operation for treating knee pain; which is the main indication for carrying out the surgery. There should also be some increased mobility as a result of this.

Having a knee replacement is a major procedure and therefore conservative (non-surgical) measures would always be tried first.

In those individuals where conservative measures have been unsuccessful then knee replacement may be indicated. Appropriate patient selection is the key to this procedure. Suitability for surgery depends on your symptoms, examination findings and investigations including x-rays or scans.

Following knee replacement it is possible to exercise with non-impact activities such as swimming or cycling. It is good to walk and keep fit with a knee replacement. A knee replacement is not designed for those people who may wish to run or do impact-type activities following the surgery.

A commonly quoted estimate for the life expectancy of a knee replacement is in the order of 15-20 years.


What are the risks associated with total knee replacement?

The risk of complication is low however all surgical procedures carry some degree of risk as well as benefit. Meticulous care is taken during knee replacement in order to try to limit the risks associated with the surgery. Risks include:

Infection – There is a risk of infection associated with any operation; it is overall low 1% (perhaps 1 in 100) with knee replacement. Extra care is taken to minimise the risk of infection, as infection following knee replacement is a very serious problem.

Stiffness – Most people are able to achieve a really good range of motion following their knee replacement surgery however in some people (perhaps 2 in 100) despite working really hard with exercises they can still get a stiff knee, which has a poor range of motion. It is not clear why this occurs; it may be because their body heals with heavy scar tissue restricting movement.

Deep vein thrombosis and pulmonary embolism (blood clots) – the risk of blood clots is assessed on an individual-by-individual basis and appropriate prophylactic (preventative) in an attempt to reduce the risk is given as required. This will be discussed with you in more detail at the time of your surgery.

Anaesthetic complications – the risk of complications as a direct result of the anaesthetic are available low. You would undergo a full preoperative assessment as part of your work up for knee replacement in order to identify and address any risk factors for surgery.

What type of anaesthetic is given?

The anaesthetic chosen for knee replacement is tailored to the individual and your anaesthetist with discuss this with you in more detail prior to surgery.

The majority of my knee replacements are carried out under spinal anaesthetic; in addition a femoral nerve block may be used. As part of an enhanced recovery programme local anaesthetic may be injected in and around the knee at the time of the surgery (peri-articular local anaesthetic). The local anaesthetic appears to make a difference with early post-operative pain relief.

What should I expect following my total knee replacement?

On return to the ward following surgery, we would aim to start you mobilising as early as possible following your knee replacement. This could be on the same day as the operation depending on how you are feeling at that time.

Our physiotherapists will show your exercises to carry out in bed and help you to mobilise around the ward.

You will be provided with pain relief as required. We routinely carry out blood tests on the first day following surgery and an x-ray of the knee on the second day.

There is no set number of days for being in the hospital. Once you are able to mobilise using crutches, have been able to climb up and down the stairs and have a good range of motion in your knee you are ready for discharge home.

Skin clips are used to close the wound and these require to be removed at 10 days following surgery.

You will be given exercises to carry out at home and it’s really important to work hard on your range of motion in order to achieve as good a result as possible with the knee replacement.

Bruising and swelling in the operated leg following surgery are normal. It is a good idea to rest, ice and elevate the leg following surgery to try to minimise swelling.

You will usually be seen at six weeks following surgery to review the progress or earlier if required.

How long does it take to get back to ‘normal’?

You should be making good progress by the time you are seen at six weeks following surgery. It is worth remembering that it does however take a number of months for the residual pain and swelling associated with the knee replacement to fully settle down.

In fact the new knee can take more than a year to fully recover and heal in following surgery and therefore continued improvement may be seen over that time period.

When can I drive following my knee surgery?

There is no set time frame for getting back to driving following surgery. You must be able to demonstrate that you are safe to drive, (i.e. can carry out an ‘emergency stop’ and handle the vehicle safely at all times). This will vary on an individual basis. As an approximate guide this is likely to be around the six-week mark following knee replacement.