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What does knee replacement surgery involve?
People often think of knee replacement as having a ‘new knee’. A knee replacement operation is a big operation which is usually performed under either a general or spinal anaesthetic (similar to an epidural which is often given during childbirth). A cut is made over the front of the knee and the worn or damaged ends of the bone are removed and replaced with an artificial joint.
How long does the operation take and how long will I be in hospital?
The actual operation part takes around 60 minutes but there is a lot of preparation involved as you need an anaesthetic. After the operation you have time to recover before returning to the ward, the whole process typically takes about 2 hours. You will usually come into hospital on the day of the operation and most patients will need to stay in for around 3 nights, but you can go home as soon as you are comfortable and able to get around safely.
Who can have a knee replacement?
This operation is usually performed for people with Arthritis of the knee. The commonest cause of Arthritis is called Osteoarthritis which is usually related to age (wear and tear), but can sometimes be caused by other things such as an injury to the knee joint. There are other forms of Arthritis that can damage a knee joint such as Rheumatoid Arthritis. I would consider knee replacement surgery for a patient with Arthritis that causes severe pain who has not been helped by other treatments. I believe it is important to realise that the operation won’t make your knee entirely normal, it is however usually very successful and over 80% of patients report a positive outcome from their surgery.
What other treatments might be considered before knee replacement?
Having a knee replacement is a big step as it is a major operation. I would only think of doing this for patients who have tried other forms of treatment and these no longer help. Other things that can help improve the symptoms of Knee Arthritis include:
What are knee replacements made from and how long do they last?
Most knee replacements consist of specialised metals and a type of very special plastic known as Ultra High Molecular Weight Polyethylene. Interestingly, Sheffield and South Yorkshire has great expertise in producing the special metals needed for knee replacements and many of the artificial knees that are implanted in people around the world started life in South Yorkshire. The metal surface articulates (glides) on the plastic.
Knee replacements are different to hip replacements and metal to metal or ceramic bearing surfaces don’t work. Many people think that knee replacements will only last a few years but in fact most modern knee replacements last a very long time. After a knee replacement over 80% of patients will still have the replaced knee working well 20 years after the surgery. Exactly how long a knee replacement will last is an individual thing and it is difficult to accurately predict as it is a little dependent on the sort of person who has the operation. Knee replacements usually wear out more quickly in young active people. This is something that I would discuss with each patient and it can be a reason to try and avoid having a knee replacement for as long as possible, particularly if you are young.
Are there any risks with having a knee replacement?
Yes, unfortunately all operations are associated with a small risk of complications or problems. As a very general rule for big operations, the risks are a little more than for small operations and a knee replacement is a big operation. For knee replacement surgery, there is a small risk of blood clots in the leg known as a Deep Vein Thrombosis (DVT) and there is a tiny risk that these can travel to the lungs known as a Pulmonary Embolism (PE). I would try and reduce the risk of this complication by using drugs to thin the blood and prescribing special stockings for a short period after the operation.
With any operation there is a risk of infection and during a knee replacement we take lots of very special precautions aimed at preventing this. For example, I would only use a special type of operating theatre called a ‘laminar flow’ theatre. This has a type of filtered airflow that only travels in one direction to try and make sure that bacteria that can circulate in normal air are prevented from getting into the wound. All theatres at Claremont Private Hospital are laminar flow and meet these very specialised standards, this is quite unique.
There are other potential side effects or complications that I would usually discuss with my patients before surgery but thankfully these are very rare.
Copyright Paul Sutton, 2018.