Total Knee Replacement for Osteoarthritis
Knee arthritis is a painful condition that can be successfully treated with replacement surgery.
This page is available to download as an information sheet.
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Is surgery the only treatment available?
There are several treatments available for knee arthritis that do not require surgery. It is possible to improve pain and function with simple painkillers, strength and supervised exercise therapy, and walking aids such as a walking stick. Even if you decide to proceed with knee replacement these treatments will also be very helpful while you are preparing for and recovering from surgery.
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What are the expected outcomes from my operation?
Modern knee replacement is a very successful treatment for knee arthritis. Most people experience excellent relief from pain and excellent levels of function. 80% of people have the best outcome with no difficulties, 15% of people will gain great benefit from their operation but some aspect of the artificial knee will be less than perfect – the joint is much better than it was with arthritis but some aspect of frustration persists. 5% of patients will have some aspect of serious complication and this can result in a permanent bad result.
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What is involved in a knee replacement?
You will have an anaesthetic. The anaesthetist will discuss the best type of anaesthetic for you. Antibiotics will be injected to your vein to reduce the risk of infection. A tourniquet will be applied to your thigh to stop any blood loss during the operation (this often leads to some thigh pain after the operation for few days). After the skin of your knee has been sterilised, a cut will be made along the leg on the outer aspect of the knee cap. The knee joint is cut open and the kneecap moved to one side. The joint is prepared by removing the arthritic bone with a saw, creating a shape to receive the new joint. The parts of the new knee are held in place with bone cement or pressed firmly into place while the bone grows on to a special coating for a permanent fix. The skin will be closed with a dissolving stitch.
After surgery you will require crutches, these will help you to walk while your knee is sore. Painkillers will also help with pain after surgery – you will benefit from painkillers for around 4 weeks after surgery.
Most people stay in hospital for 4 nights after their operation and can go home for the rest of their recovery.
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Does anything ever go wrong?
General complications from operations include wound infections, blood clots in the legs or the lungs, heart attacks, strokes, bleeding to the wound site, or reactions to medications. Thankfully, these problems are not common, but you will be monitored while in hospital.
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Infection of the knee replacement
This problem is seen around 1 per 150 knee replacements. The risks are higher if the person has diabetes, is taking strong immune therapy medication, or is obese. Recognising an infected joint is important in the early stages after surgery as it can be managed well with urgent surgery and antibiotics. The signs of infection include fevers and chills, a red-hot wound, persistent fluid coming from a wound.
If you experience any of these please contact the office before you speak with your GP.
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Numbness of the skin around the scar
This is extremely common after many types of knee surgery. Some of the nerves running close to the skin are cut as part of the incision to access the knee joint. Often the area of numbness will decrease over time, but some part will remain as a permanent area. Placing the skin incision towards the outside aspect of the knee can help to reduce this side effect of the surgery.
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Pain and swelling
It is expected that most knees will be warm, swollen, and uncomfortable for a few weeks after the surgery, continuing with pain killers and performing proper rehab exercises is key during this period. A small number of patients experience a much worse period of stiffness and pain, often this can be managed with a longer period of painkillers and exercise, occasionally the knee joint is very stiff and may require a manipulation in the operating theatre under anaesthetic to increase the range of movement.
Most knees are swollen for up to ONE YEAR after surgery.
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Stiffness
Rarely a knee will remain very stiff after replacement surgery, this can be very challenging for the person having the knee operation, often the patient, family and surgeon are disappointed with the result. Sometimes a manipulation will improve the range of movement, less often keyhole surgery has a role to play. Revision of the knee replacement is not usually considered unless there is some suggestion of a technical problem with the knee replacement. The most frequent association for a stiff knee after knee replacement surgery is a very stiff knee before surgery.
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Difficulty kneeling
Probably the most common difficulty after knee replacement surgery is kneeling. This is permitted and will not cause any harm to the artificial joint, but it is often quite uncomfortable, and most people avoid this activity after their surgery.
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Nerve injury
The nerves that supply the foot and ankle run behind and to the outer side of the knee. Either of these may be injured at surgery. Thankfully this is a rare event as most nerve injuries do not fully recover. Nerve injury does not indicate that anything has been done wrong by the surgeon, nevertheless it can be a very distressing complication.
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Blood clots
Blood clots can occur in the veins of the leg or can occur in the lungs. Many of the recovery tasks given to you by the physiotherapists and nursing staff are designed to reduce the risk of you getting these clots. Additionally, blood thinners given to you as an injection or tablet to lessen the risk of these clots. You will need to continue taking these for around 2 weeks after your surgery.
Small volume blood clots that are only found below the level of the knee joint may not require high doses of blood thinners but can be monitored with repeat scans and low doses of blood thinner.
Please tell the team if you are planning any long-haul flights in the weeks after your operation – this increases your risk of blood clots in your leg and we will usually recommend some blood thinners for your trip.