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Knee replacement

Published by Bupa's health information team, September 2008.

This factsheet is for people who are planning to have a knee replacement procedure, or who would like information about it.

Knee replacement involves replacing a knee joint that has been damaged or worn away, usually by arthritis or injury.

Your care will be adapted to meet your individual needs and may differ from what is described here. So it's important that you follow your surgeon's advice.

• Animation - How a knee replacement is carried out
• About knee replacement
• Types of artificial knee
• What are the alternatives?
• Preparing for your operation
• About the operation
• What to expect afterwards
• Recovering from knee replacement surgery
• What are the risks?
• Questions and answers
• Related topics
• Related Bupa products and services
• Further information
• Sources

How a knee replacement is carried out

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About knee replacement

Your knee joint is made up by the ends of your thigh bone (femur) and shin bone. These normally glide over each other smoothly because they are covered by shock-absorbing cartilage. If the cartilage is damaged by injury or worn away by arthritis, for example, it can make the joint painful and stiff.

A new knee joint can help improve your mobility and reduce pain.

Depending on the condition of your knee joint, you may have part or all of your knee joint replaced. A total knee replacement is more common.

Types of artificial knee

Artificial knee parts can be made of metal and/or plastic.

Some artificial knee parts need a substance called 'bone cement' to keep them in place. Others are coated with a chemical which encourages bone to grow into it to hold the parts in place.

A knee replacement usually lasts for at least 10 to 15 years.

What are the alternatives?

Surgery is usually recommended only if non-surgical treatments, such as physiotherapy and exercise, taking medicines or using physical aids like a walking stick, no longer help to reduce pain or improve mobility.

Alternative surgical procedures include osteotomy (where the leg bones are reshaped).

Your surgeon will explain your options to you.

Preparing for your operation

Your surgeon will explain how to prepare for your operation. For example if you smoke you will be asked to stop, as smoking increases your risk of getting a wound infection and slows your recovery.

The operation usually requires a hospital stay of about five days and it's done under general anaesthesia. This means you will be asleep during the operation. Alternatively you may prefer to have the surgery under spinal or epidural anaesthesia. This completely blocks feeling from your waist down and you will stay awake during the operation.

Your surgeon will advise which type of anaesthesia is most suitable for you.

If you are having a general anaesthetic, you will be asked to follow fasting instructions. 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 beforehand.

At the hospital your nurse will may do some tests such as checking your heart rate and blood pressure, and testing your urine.

Your surgeon will usually ask you to sign a consent form. This confirms that you understand the risks, benefits and possible alternatives to the procedure and have given your permission for it to go ahead.

You will also be asked to consent to placing your name on the National Joint Register, which is used to follow up the safety, durability and effectiveness of joint replacements.

You may be asked to wear a compression stocking on the unaffected leg to help prevent blood clots forming in your veins (deep vein thrombosis, DVT). You may need to have an injection of an anti-clotting medicine called heparin as well as, or instead of, stockings.

About the operation

A knee replacement usually takes up to two hours.

Your surgeon will make a single cut (10 to 30cm long) down the front of your knee.

Your kneecap is moved to one side to reach the knee joint. The worn or damaged surfaces are removed from both the end of your thigh bone and the top of your shin bone. The surfaces are shaped to fit the artificial knee joint. The new joint is fitted over both bones.

Sometimes the back of your kneecap is replaced with a plastic part. This is called patellar resurfacing.

After the new joint is fitted, the skin cut is closed with stitches or clips and covered with a dressing. Your knee will be tightly bandaged to help minimise swelling.

What to expect afterwards

You will need to rest until the effects of the anaesthetic have passed. You may not be able to feel or move your legs for several hours after an epidural anaesthetic.

You may need pain relief to help with any discomfort as the anaesthetic wears off.

For the first day or so, you may have an intermittent compression pump attached to special pads on your lower legs. By inflating the pads, the pump encourages healthy blood flow and helps to prevent DVT. You may also have a compression stocking on your unaffected leg. This helps to maintain circulation.

Starting from the day after your operation, a physiotherapist (a specialist in movement and mobility) will usually guide you daily through exercises to help your recovery.

You will be in hospital until you are able to walk safely with the aid of sticks or crutches. When you are ready to go home, you will need to arrange for someone to drive you home. You should try to have a friend or relative stay with you for the first week.

Your nurse will give you some advice about caring for your knee and a date for a follow-up appointment before you go home.

Dissolvable stitches will disappear on their own in seven to 10 days. Non-dissolvable stitches and clips are removed 10 to 14 days after surgery.

Recovering from knee replacement surgery

If you need them, you can take over-the-counter painkillers such as paracetamol or ibuprofen. Follow the instructions in the patient information leaflet that comes with the medicine and ask your pharmacist for advice.

The exercises recommended by your physiotherapist are a crucial part of your recovery, so it's essential that you continue to do them.

You will be able to move around your home and manage stairs. You will find some routine daily activities, such as shopping, difficult for a few weeks. You may need to use a walking stick or crutches for up to six weeks.

You may be asked to wear compression stockings for several weeks at home. They are difficult to put on and take off, and you will need someone to help you with this.

When you are resting, you should do so with your leg raised and your knee supported to help prevent swelling in your leg and ankle.

Depending on the type of work you do, you can usually return to work after six to eight weeks.

Follow your surgeon's advice about driving. You shouldn't drive until you are confident that you could perform an emergency stop without discomfort.

What are the risks?

Knee replacement surgery is commonly performed and generally safe. However, in order to make an informed decision and give your consent, you need to be aware of the possible side-effects and the risk of complications of this procedure.

Side-effects

These are the unwanted, but mostly temporary effects of a successful treatment, for example feeling sick as a result of the general anaesthetic.

Your knee will feel sore and may be swollen for up to twelve months.

You will have a scar over the front of the knee. You may not have any feeling in the skin around your scar. This can be permanent.

Complications

This is when problems occur during or after the operation. Most people are not affected. The possible complications of any operation include an unexpected reaction to the anaesthetic, excessive bleeding or developing a blood clot, usually in a vein in the leg (DVT).

Specific complications of knee replacement are uncommon, but can include those listed below.

• Infection of the wound or joint. Antibiotics are given during and after surgery to help prevent this.
• Unstable joint. The knee joint may become loose and you may require further surgery to correct this.
• Damage to nerves or blood vessels. This is usually mild and temporary.
• Scar tissue. This can build up and restrict your movement. Further surgery may be needed to correct this.

The artificial knee joint usually lasts for 10 to 15 years, after which you may need to have it replaced.

The exact risks are specific to you and will differ for every person, so we have not included statistics here. Ask your surgeon to explain how these risks apply to you.

Related topics

• Caring for surgical wounds
• Compression stockings
• Deep vein thrombosis
• Epidurals for surgery and pain relief
• General anaesthesia
• Knee injuries
• Osteoarthritis

Further information

• British Association for Surgery of the Knee
  www.baskonline.com
• Arthritis Research Campaign (arc)
  0870 850 5000
  www.arc.org.uk

Sources

• Total knee replacement: a guide for patients. British Association for Surgery of the Knee and the British Orthopaedic Association. 2007. www.boa.ac.uk
• Surgical treatment of osteoarthritis of the knee. American Academy of Orthopaedic Surgeons. http://orthoinfo.aaos.org, accessed 6 February 2008
• Argenson J-NA, Parratte S, Fletcher X et al. Unicompartmental knee arthroplasty. Clin Orthop Relat Res 2007; 464:32-36. www.clinorthop.org/index.html
• Surgery for arthritis: total hip and knee joint replacement. Arthritis research campaign. www.arc.org.uk, accessed 6 February 2008
• Mini-incision for total knee replacement. National Institute for Health and Clinical Excellence (NICE), 2005, Interventional Procedure Guidance 117. www.nice.org.uk
• Osteoarthritis - in depth - management Issues. National Library for Health. Clinical Knowledge Summaries. www.cks.library.nhs.uk, accessed 6 February 2008
• Osteotomy and unicompartmental knee arthroplasty. American Academy of Orthopaedic Surgeons. http://orthoinfo.aaos.org, accessed 6 February 2008
• Feller JA, Bartlett RJ, Lang DM. Patellar resurfacing versus retention in total knee arthroplasty. J Bone Joint Surg Br 1996; 78:226-228. www.jbjs.org.uk
• Activities after a knee replacement. American Academy of Orthopaedic Surgeons. http://orthoinfo.aaos.org, accessed 14 April 2008

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. It has also been reviewed by Arthritis Research Campaign (arc). The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.

Publication date: September 2008