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Total knee replacement surgery, which is also known as total knee arthroplasty, is an operation to replace a worn, diseased or damaged knee with an artificial one. This common operation is carried out more than 70,000 times a year in the UK alone.

Knee replacement surgery can be considered for adults of any age, but it is much more common within the 60- to 80-year-old age group. Approximately 80 per cent of all knee replacement operations carried out will be on women.

A replacement knee can provide long-term relief and last for over 20 years in the best cases.

When a knee replacement is considered

If a knee joint becomes so damaged or worn that mobility is reduced and significant pain is experienced even while resting, a replacement knee joint may be considered.

The most common cause of symptoms leading to full knee replacement surgery is osteoarthritis. Other health conditions can also cause damage to the knee joint, including injury, unusual bone growth, rheumatoid arthritis and gout.

Candidates for knee replacement surgery

A knee replacement is considered major surgery, so it will usually only be considered when other non- or less-intrusive treatments have been tried but have proven ineffective.

Knee replacement surgery may be considered if there is severe pain, stiffness and swelling in the joint and thew candidate’s mobility is significantly reduced. This includes knee joint pain that interferes with their quality of life, sleep and carrying out everyday tasks, and impacts their ability to work or have a social life.

Those undergoing knee replacement surgery must be healthy enough to be able to cope with the effects of a major operation and the rehabilitation that is required afterwards.

Advantages of total knee replacement

Full knee replacement surgery usually lasts for between 15 and 20 years, but it can last longer than 20 years if the knee is well cared for and not placed under undue strain. Given the life span of a knee replacement if the surgery takes place when a patient is fairly young then there is a chance the patient will need another knee replacement at some stage and hence why non-surgical solutions are typically offered in the first instance for those who are younger.

There are three key areas in which replacement knee surgery is likely to help:

Pain relief: It should be noted that every individual is different. Depending upon the underlying conditions and the individual’s overall health, there may be ongoing pain even after surgery; however, it would be reasonable to expect a significant improvement in most cases.

Improved mobility: Knee pain can mean individuals find it difficult or impossible to walk long distances; in fact, even very short distances and moving around the home or work can be challenging. Reduced mobility can lead to weight gain and ill health.

Reduced treatment: Long-term use of non-invasive medications, such as opioid pain relievers, can cause complications such as dependence. Other treatments and medications can also have long-term implications. Knee surgery reduces or eliminates the need for other treatments connected with the knee.

Risks of total knee replacement surgery

Although considered a major operation, full knee replacement surgery is a fairly straightforward operation and complications are not usual.

As with any operation, there are risks. These can include bleeding, swelling, infection, stiffness, and possible damage to nerves, ligaments or arteries. If a new knee joint proves unstable, further surgery could be required to remediate; however, this occurs only in rare cases.

Most at risk for complications are those with underlying and pre-existing health conditions, such as heart disease, diabetes that is not well managed, or those with a weakened immune system. The surgeon will take these conditions into account when making a recommendation for surgery.

Total knee arthroplasty is successful in the vast majority of cases; however, as with any surgery, any risks should be carefully considered and weighed against the potential benefits before deciding whether to proceed. Surgery is typically seen as the last option once all non-surgical options have been exhausted.

Preparing for knee replacement surgery

Before going into hospital for surgery, patients should ensure that they discuss the procedure, the possible outcomes and the recovery process fully with their medical practitioner.

It is important to stay as active as possible, with any gentle exercise that patients can undertake that help to strengthen the muscles around the knee helping to ensure a quicker and easier recovery. Appropriate exercise can include walking, swimming, and using an exercise bike. A physiotherapist can advise on helpful exercises.

About the procedure

Knee replacement surgery will usually be performed under general anaesthetic, spinal anaesthetic or epidural. The surgeon will cut the front of the knee to expose the kneecap, which will be moved aside to access the joint.

The damaged ends of the shin bone and the thigh bone will be cut away and the ends will be precisely measured and shaped to ensure a good fit for the replacement. The end of the thigh bone and shin bone are replaced by metal plates, with a spacer made of special plastic placed between the metal pieces. This acts in the same way as cartilage to reduce friction in the joint.

The back of the kneecap could also be replaced as part of the procedure, depending upon the reasons for the replacement.

The wound will then be closed with either clips or stitches and a dressing applied over the top. A splint may occasionally be used to keep the leg immobile, but this is rare. Patients are usually encouraged to move their knee as soon as possible and invariably get the patient out of their bed by the end of the day.

Recovery from total knee replacement surgery

Recovery times vary depending upon each individual, but patients can generally expect to be in hospital for between three and five days.

A walking frame or crutches are likely to be needed, and patients may need assistance with particular activities. A physiotherapist will provide advice and recommend exercises to help strengthen the knee and encourage mobility without placing excessive strain on the new joint whilst it is healing. It is also advisable to keep the leg raised whilst resting, which will help to reduce swelling and improve circulation.

Occasionally, additional help may be needed. In these cases, a passive motion machine may be used to slowly moves the knee while the patient is in bed. It may be necessary to supplement the support and protection initially to protect the new joint and help instabilities. A medical professional will advise on the appropriate use of supports or braces if required.

Most people will be able to stop using a frame or crutches about six weeks after their surgery. At this point, it should also be possible to participate in most everyday activities again; however, pain can take up to three months post-surgery to settle and patients may experience some swelling up to a year after the operation.

It is important for patients to actively rehabilitate following knee replacement surgery. The risk of the new joint not working as well as hoped or feeling stiff or weak is increased for those not properly following professional post-operative advice. This will include following a schedule of rest, exercise and medication.

A full recovery

When the scar tissue has healed and the muscles have been restored - usually takes two years; however, rigorous activities that could damage the knee must be avoided even after this time to help reduce the likelihood of damage and to prolong the life of the artificial knee.

Total Knee Replacement - Knee Replacement Operation - OA Knee Pain X-ray of a total knee replacement

The long-term plan after knee replacement surgery

Once a patient has gone through the recovery process after having knee replacement surgery, there are a number of things they can do to help minimise future problems and prolong the life of their new artificial joint. These include:

Losing any excess weight

Excess weight places a greater strain on the knee joints, whether artificial or not. Fat is also known to produce hormones that increase inflammation. Patients who were overweight prior to their surgery or who have gained weight during the recovery process can help their long-term prospects significantly by losing the excess weight. A suitable diet plan should be followed that includes fresh fruit and vegetables, minimises sugary foods and empty carbs, and cuts out most deep-fried food or unhealthy snacks.


Once the recovery process has been completed, it is likely that patients will no longer have specific physiotherapist-designed exercises that they are given to follow; however, to maintain healthy joints overall, it is important to take regular gentle exercise. Walking and swimming are typically recommended and can help to keep the muscles around the knee joint strong. This will help to prolong the life of the artificial joint, as it will experience less stress.

Good footwear

The effects of non-supportive or ill-fitting footwear on joints and posture are often underestimated. Poorly-fitted or non-supportive shoes will put undue stress on the new artificial joint. You will also be walking with a different gait post-surgery than you did previously, which can continue to develop during the first six months of recovery. It is important that any medical advice given for footwear is followed and that shoes are properly fitted. It is also important to repair or replace footwear when needed, as support can be lost through wear.

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