KNEE replacement
Total and uni-compartmental knee replacements are one of our most common and successful operations. Replacement surgery relieves pain and restores mobility for patients with many types of arthritis.
Knee arthritis
Many patients suffer from knee arthritis. This may be from wear and tear in older age, post-traumatic from previous injury, as a result of joint infection, or even various causes of inflammatory arthritis such as rheumatoid arthritis.
Common symptoms that patients experience include: pain around the front and sides of the knee, sharp pains with movement; a sense of giving way or loss of confidence in the knee; stiffness; pain when sleeping. Not all knee pain is the same and commonly even hip arthritis is felt down at the knee.
Before considering knee replacement surgery you should exhaust all non-operative treatment options. Knee surgery is frequently very successful, however all prosthesis have a lifespan and all surgery carries some risks.
Knee arthroplasty
Total knee replacement surgery replaces the worn arthritic cartilage and bone of the joint surfaces between the tibia and femur. The patella may also be resurfaced too in some cases.
It is important to realize that the surgeon does not 'replace' your knee with a new one. Usually less than 1cm is removed from both bones in the joint. The term "arthroplasty" roughly means to form a new joint.
The worn cartilage articulation is replaced by a mechanical one which removed the painful grinding. The new joint is also smooth again so it doesn't catch or give way.
It takes some time to get used to the new different joint but eventually you can move comfortably and confidently.
Knee prosthesis
The prosthesis used is a polished cobalt-chrome steel bearing, with a titanium backside for ingrowth and cementation. The bearing is a highly cross-linked polyethylene insert. The lower tibial component is usually titanium which is cemented to the bone using a polymer known as PMMA (polymethylmethacrylate)
These are all very mature technologies that have been used in clinical practice for decades now. it is very rare to have any allergic reactions however other options exist for patients with specific allergies to implanted surgical prosthesis.
With cemented knee replacement the joint is immediately strong and stable. This means it can take your full body weight as soon you recover from anaesthetic and are able to walk.
The bearing components can wear over time like all mechanical devices. Current data suggests that 95% of knee replacements will last at least 10 years, and almost 90% for 20 years. Ask your surgeon for more detail regarding your particular situation.
Should I have knee replacement surgery?
Knee replacement is elective surgery. This means you may want it to improve your quality of life, but nothing terrible will happen if you don't. If you have exhausted all other treatments however it may be the best long term solution for pain relief and regaining your mobility.
There are at least 3 questions your surgeon will consider:
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Is the knee pain caused by arthritis?
If not knee replacement is usually not be the right option for you. Your surgeon will examine your knee and x-rays and advise you about this. -
How old are you?
Sometimes patient think they are too old. Your surgeon however only wants to know how fit you are. In some respects older patient will do better as they wear their prosthesis slower. Younger patients have a greater concern as they might need to have revision surgery in the future. -
Is your pain worth going through surgery?
This is a personal question. You need to talk in detail with your surgeon about the risks and benefits. Even if your knee x-rays look worn, if you are functioning well without frequent pain then you don't need surgery.
What to expect?
A normal well functioning knee replacement should give you years of comfortable mobility. The knee should feel stable and allow you to walk, sit and sleep comfortably.
You can run if you need to, but regular distance running will probably make the components wear out faster and not really what the replacement is intended for. Hiking, cycling and swimming are all perfectly fine however.
You need to expect pain and discomfort for the first 3 weeks. The surgery is quite invasive and the knee will be irritable and swollen. Your surgeon will ensure you achieve a good range of motion during surgery, however you will have to work hard to regain and maintain this after surgery.
Most patients are in hospital a few days, and a wound check appointment is scheduled at 10-14 days after surgery to ensure the skin healed and no signs of infection. You will have x-rays before and after surgery.
You will initially walk with assistance and a rolling frame. Then you will progress to a small walker, crutches or stick. Before you leave hospital you need to be able to care for yourself and get around safely.
More details are available in our information for patients section.
Risks of knee surgery
All surgery has risks and this is moderately large surgery. There are general risks of all surgery/anaethetic of this magnitude which include: risks of surgery and anesthetic including stroke, heart attack and even death. You will be assessed first and all measures to ensure these are minimal.
With all joint replacement surgery infection is a concern and may affect 1 or 2%. This can require further operations or antibiotics. You will be given antibiotics before the surgery starts and meticulous sterile care in taken in operating theatre.
The biggest problem most patients have with knee surgery is stiffness. Rest assured your surgeon will try to maximise your range of motion at the time of operation, after surgery it is most important however that you work hard on your stretches to maintain this correction.
More information is available in our information for patients section.