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Knee replacement

Your specialist has recommended that you have a knee replacement, this leaflet provides some standard information and advice about the procedure. However, you should always follow the instructions of your own specialist.

If you have any unanswered questions or concerns, please do not hesitate to ask your specialist or nurse for more information. It is natural to feel anxious, but often knowing what to expect can help.

This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.

During a knee replacement, the damaged or worn parts of the thigh and shin bones that form the knee joint are replaced with metal and plastic parts that glide over each other smoothly. It is a major operation, and you will be in hospital until you are able to walk safely with the aid of sticks or crutches. This is typically between five and ten days.

A knee replacement operation is usually performed under a general anaesthetic. For more information on general anaesthesia, please see the separate leaflet.

Knee replacement

Your specialist or hospital will talk to you about admission procedure, however before you come into hospital, you will also be asked to:

attend a pre-assessment clinic for routine tests two or three weeks before your operation. This will be an opportunity for you to ask any questions. A physiotherapist will also talk to you about your home requirements, so that any necessary arrangements for aids and services can be made in advance of your admission. Strengthening the leg muscles through exercise before surgery can also speed up your recovery and the physiotherapist will discuss this too

have a bath or shower on the day of your admission

remove any make-up, nail varnish and bulky or sharp jewellery. Rings and earrings that you would prefer not to remove can usually be covered with adhesive tape

follow any fasting instructions given to you. Typically, you must not eat or drink for about six hours before a general anaesthetic. However, some anaesthetists allow occasional sips of water until two hours before

After you have been shown to your room, your nurse will check if you have been well since the pre-assessment. Your surgeon and anaesthetist will also visit you. The surgeon will use a pen to clearly indicate the leg to be treated. This is good time to ask any outstanding questions about your treatment.

The nurse will help you prepare for surgery and will do some simple tests such as taking your blood pressure and pulse, and may ask you for a urine sample. You may be asked to put on compression stockings to help prevent blood clots from forming in the veins of your legs.


You will be given a consent form to sign. By doing this, you confirm that you understand what the procedure involves, including the benefits and risks, and give your permission for it to go ahead.

Please see the later for further information about the possible side-effects and complications of this procedure. You need to know about these in order to give your informed consent.

About the operation

An incision, usually around 6-12 inches (15-30 cm) long is made down the front of the knee. The replacement joint is attached to the bones with a special cement. The kneecap may either be replaced or trimmed before the surgeon closes the incision with stitches or clips. Fine plastic drainage tubes may be left in place for up to 48 hours after the operation.

The operation usually takes between one and two hours, and your relatives should expect you to be away from your room for at least three hours.

After your operation

You will be taken from the operating theatre to a recovery room, where you will come round from the anaesthetic under close supervision. After this, you will be taken back to your room, where a nurse will make you comfortable. When you feel ready, you can begin to drink and eat, starting with clear fluids such as water or fruit juice.

Back on the ward

During your stay in hospital, every effort is made to keep any discomfort to an acceptable level and your anaesthetist will discuss arrangements for pain relief. After the first week, you will probably only need mild painkillers.

The physiotherapist will visit you daily to guide you through exercises. Generally, you will be encouraged to move your new knee from the first day after the operation. You may be asked to use a "continuous passive motion" machine. This continuously and gently moves your knee, gradually increasing the amount of movement each day.

By the time you go home, you will be able to walk with sticks or crutches and will have learned how best to move about and manage daily tasks.

Going home

You will need to make arrangements to be driven home. Before you go home, a nurse will advise you about caring for surgical wounds, hygiene and bathing. A follow-up appointment in the outpatient clinic will be arranged for you.

After you return home

If you need them, continue taking painkillers as advised by your specialist or the hospital. Your knee will probably be sore for around six weeks.

You will be able to move around your home and manage stairs, but you will find that some routine daily activities are difficult for a few weeks and will need to ask family or friends to help. For example, you may not be able to go shopping for the first few weeks. When you are not walking, you should rest with your leg raised to help prevent swelling in the leg and ankle.

If you work, you will probably not be able to return for at least six weeks after your operation. You will not be able to drive until your specialist advises you that it is safe.

Its crucial that you continue with the exercises recommended by the physiotherapist, as these will promote healing and help you recover more quickly. Your new knee will continue to get better for at least six months.


A knee replacement is a commonly performed and generally safe surgical procedure. For most people, the benefits in terms of pain reduction and improved mobility are far greater than the disadvantages. However, all surgery does carry some element of risk. This can be divided into the risk of side-effects and the risk of complications.


These are the unwanted but mostly mild and temporary effects of a successful treatment. Examples of short-lived side-effects include feeling sick as a result of the general anaesthetic and painkillers. After a knee replacement operation, the knee may be sore on moving and swollen for up to three months. The outer side of the knee and scar are likely to stay numb. Sometimes this is permanent.

Occasionally, a blood transfusion is required to replace blood lost after the surgery.

In the longer term, the artificial joint will not last forever and, after years of use, a further operation may be needed.


This is when problems occur during or after the operation. Most people are not affected.

The main possible complications of any surgery are bleeding during or soon after the operation, infection, and an unexpected reaction to the anaesthetic.

Specific complications of a knee replacement include:

  • problems with healing: in about 5% of cases the incision may not heal properly, increasing the risk of infection. Plastic surgery may be required
  • instability: in 1-2% of cases it is not possible to make the new knee fully stable and a knee brace may have to be worn
  • dislocation: in about 1% of cases the kneecap becomes dislocated after knee replacement surgery
  • a buildup of scar tissue: occasionally this restricts movement. Another operation may be performed to break down the scar tissue. In rare cases, the loss of movement may be permanent
  • blood clots: for up to six weeks after the operation, it is possible to develop a blood clot (known as a deep vein thrombosis or DVT) in the veins of the leg. This clot can break off and cause a blockage in the lungs. In the majority of cases, this is treatable, but it can be a dangerous condition. You may be given medicines or compression stockings to help prevent a DVT

The chance of complications depends on the exact type of operation and other factors such as your age and general health. You should ask your surgeon to explain how these risks apply to you.


1. How long will my knee replacement last?

Almost all knee replacements last at least 10 or 15 years, and some as long as 20 years.

Replacements joints are designed to last for a long time. The modern materials used are strong enough to stand up to the requirements of young and active people.

Currently just over nine out of 10 artificial joints used for knee replacement last for 10 years or more. However, there is increasing research into the design and material of replacement knee joints to make them last longer.

You should have an X-ray on your knee at least every five years after your operation. If your replacement joint is loosening or breaking, you may need another operation to correct this.

2. Are there any sports/activities I shouldn't take part in after my knee replacement?

Once you are fully recovered you can do exercise and sport. However you shouldn't take part in high-impact exercises such as running and jumping.

During your recovery your physiotherapist will recommend exercises for you that will improve your strength and range of motion. You should do these for at least two months after your operation.

As you recover you can start swimming and do more walking to strengthen your muscles around the joint. You can gradually start cycling but if you feel any pain than you must stop and allow yourself more time to recover.

When you have made a full recovery, you can have a more active lifestyle. However it's important that you don't take part in high-impact activities or contact sports. So you shouldn't do sports such as football, rugby, basketball, squash, skiing or anything involving squats, jumping or weightlifting. But you can do low-impact sports such as golf, bowls or gentle doubles tennis or dancing.

Regular exercise will help to improve and maintain your mobility. When returning to any sport it's important to take your time to rebuild your strength and co-ordination.

You may find that you can't return to your chosen sport at the same level as you were before. Your risk of injury is greatly increased if you take part in competitive, rather than recreational, sport.

Your doctor, surgeon or physiotherapist will be able to give you more information about what activities are suitable.

3. What can I do to make my recovery easier?

You should try to be as fit and healthy as possible before your operation and prepare your home for when you return.

If you are having a knee replacement it's a good idea to try to be as fit and healthy as possible before your operation to speed up your recovery.

If you smoke you will be asked to stop, as smoking can increase your chances of getting a wound infection and slows your recovery. If you are overweight your doctor may recommend a weight-loss programme.

You can exercise to strengthen your upper body. This will help you to get around after the surgery when using walking aids such as crutches.

If it's possible you should try to strengthen your leg muscles. Strengthening the muscles around your knee will speed your recovery and will make it easier to perform the postoperative exercises.

Your surgeon or physiotherapist will be able to recommend exercises for you.

It's a good idea to prepare your home for when you return from hospital. This may mean rearranging furniture to make it easier to move around, and placing commonly used items at arm level so you don't have to reach for them. It's also a good idea to stock up on non-perishable food such as frozen or tinned items, so that you don't need to go shopping immediately after your surgery.

You may need someone to help during the first few weeks after surgery. It's a good idea to arrange to have a friend or family member stay with you for a couple of days after the operation.

Further information 

  • American Academy of Orthopaedic Surgeons
  • British Association for Surgery of the Knee
  • Arthritis Research Campaign (arc)
    0300 790 0400



  • Total knee arthroplasty. eMedicine., accessed 22 August 2010
  • Knee surgery. Arthritis Research UK., accessed 2 August 2010
  • Total knee replacement. American Academy of Orthopaedic Surgeons., accessed 29 July 2010
  • Osteoarthritis. Clinical Knowledge Summaries, accessed 29 July 2010
  • Surgical treatment of osteoarthritis of the knee. American Academy of Orthopaedic Surgeons., accessed 29 July 2010
  • Is there any evidence that smoking impairs wound healing? Trip Answers., accessed 7 September 2009
  • Total knee replacement: a guide for patients. British Orthopaedic Association, accessed 29 July 2010; 2 August 2010
  • Jacobs W, Clement DJ, Wymenga AAB. Retention versus sacrifice of the posterior cruciate ligament in total knee replacement for treatment of osteoarthritis and rheumatoid arthritis. Cochrane Database of Systematic Reviews 2005. DOI: 10.1002/14651858.CD004803.pub2
  • Activities after a knee replacement. American Academy of Orthopaedic Surgeons., accessed 3 August 2010
  • Preparing for joint replacement surgery. American Academy of Orthopaedic Surgeons., accessed 2 August 2010

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