Knee Joint Replacements

Knee joint replacement involves replacing part or all of a knee joint that has been damaged or worn away with a prosthesis (new joint made of metal and plastic) to reduce pain and improve function.

Knee replacement surgery is the most common joint replacement surgery performed. There are about 80,000 knee replacements carried out per year in the UK and 130,000 in the US. Knee replacements were first carried out in the 1940’s and have developed significantly since then.

There are two types of knee joint replacement:

1) Partial Knee Replacement - where only one side of the knee joint is removed and replaced with a metal and plastic prosthesis. It is sometimes known as a Unicompartmental Knee Replacement (UKR) or Unicondylar Knee Arthroplasty
2) Total Knee Replacement – all the bone and cartilage at the bottom of the thigh bone (femur) and at the top of the shin bone (tibia) are removed. The entire knee joint is then replacement with a prosthesis (implant) made of metal and plastic. Also known as a TKR or Total Knee Arthroplasty.

Reasons For Knee Joint Replacement

Knee Replacements are most commonly carried out to treat advanced Osteoarthritis of the knee. This is when the cartilage in the knee becomes damaged and wears away, causing pain and limiting function.

Your knee joint is made up of the ends of the thigh and shin bone. They are lined with cartilage which allows the bones to glide smoothly over each other. With osteoarthritis of the knee, the cartilage thins, and the bone underneath begins to thicken and lays down new bony spurs, called osteophytes. As arthritis progresses, the cartilage can wear away altogether and you get bone rubbing on bone.

Arthritis knee pain can end up so severe that normal daily activities, eg walking and going down stairs become extremely painful and difficult. The knee can even become deformed. When this happens, the best course of action is knee joint replacement.

Indications for Knee Replacement

People are often unsure at what stage of arthritis surgery is appropriate. There are no hard and fast rules but the following criteria are a good guideline:

1) The pain in your knee is affecting your normal daily activities eg walking, stairs etc
2) Your knee pain is affecting your sleep – frequently keeps you awake or wakes you up
3) You have tried exercises to strengthen your knee for a reasonable period with no effect
4) You are in severe pain

If your symptoms are not as severe as these, a knee joint replacement is not needed. Check out the Arthritis section for more treatment options for arthritis

Some people worry about leaving it too long before having a knee replacement. Rest assured, there is no need to worry. Arthritis does not get to a stage where it is so bad that the surgery can’t be performed, so there is no harm in waiting. However, if by waiting you are losing lots of strength in your muscles from not being able to keep active, it is likely to take you longer to recover after surgery.

Alternatives to Surgery

Most people with Osteoarthritis of the knee do not require a knee replacement. Arthritis knee pain can often be successfully managed without the need for surgery, by using treatments such as exercises, pain relief, PRICE and injections. See the Knee Arthritis Treatment section for more info on effective ways to treat osteoarthritis of the knee.

Knee joint replacement is only performed when arthritis has become advance and non-surgical treatments such are no longer adequately controlling knee pain, or when function is serious inhibited.

If treatment is not working anymore, there are also some simpler operations that can be effective:
1) Knee Arthroscopy: Key-hole surgery where damaged parts of cartilage are removed
2) Osteotomy: Where a small amount of diseased bone is removed

Want to Know More?

Find out more about the surgery itself, the rehab and recovery process, common problems associated with knee replacements and Frequently Asked Questions by clicking the appropriate link below:

Total Knee Replacements

Partial Knee Replacements

Go to Knee Surgery Section or Homepage

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Updated 30th April 2013
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