Total Knee Replacement is now a routine procedure in Orthopaedic Practice and is one of the most common operations undertaken in Orthopaedics. The procedure is undertaken for people with osteoarthritis of the knee and occaisionally to treat fractures or severe ligament injuries of the knee joint.
85% of people who have a TKR either have a good or excellent result, and its an operation that can transform a person's life. However there can be problems with this operation.
The main complications include infection (1% risk), vein thrombosis (1% risk) and loss of movement (5% risk).
Treatment is given to reduce these risks, but infection is a serious complication and would require further surgery.
The better movement in the knee is prior to surgery, the better it will be after surgery. If the knee does become stiff after TKR the knee may require manipulation under an anaesthetic.
People's main concern regarding knee replacement is how long the knee replacement will last. Historically the usual cause for loosening of a knee replacement is because of the wear of the plastic component of the knee replacement. Modern manufacturing techniques of the plastic components have now minimised this problem.
In the medical literature the results of TKR are that 95% of TKRs do not loosen up to 15 years after implantation. Obviously in younger more active people or in people who are very overweight, the wear problems maybe more of an issue.
About 10-15% of people will have some pain in their knee after TKR despite a "surgically successful" TKR. This is a different pain to that of arthritis, the cause of the pain maybe difficult to identify. The possible causes include: infection, instability, incorrect sizing or position of the knee components, kneecap pain, nerve irritation or hypersensitivity (Reflex Sympathetic Dystrophy RSD), persistent inflammation (knee tissues continue to be irritated by the knee replacement) and stiffness and scarring around the knee replacement. Pain referred from other areas such as the hip and the back may be the cause.
Some of these problems can be corrected, but some people will have pain in the knee replacement for which no cause can be found and revision surgery in this situation is usually unsuccessful. In this situation, the person will usually cope and accept that because their new knee is a false joint it may therefore not function as a normal knee joint.
The people that do well following TKR are of normal weight, have a good range of knee movement, good muscle strength in the quads (Thigh Muscle) and well motivated and informed.
After your knee replacement you will swap a painful arthritic knee for a painful swollen, heavy, tight and stiff knee for the first few weeks. This is because with a big operation there is a lot of tissue swelling and not a lot of space for the swelling to move to. There maybe more pain at night because of the swelling and inflammation.
The amount of swelling varies from person to person, the major swelling begins to subside between 6-12 weeks. The difficulty for people is maintaining the range of movement in the knee in these first few weeks. It is about 3 months before people really start to get the benefit from the new knee.
Once you have turned the corner then you will seldom have any major problem.
A small number of people continue to have some significant swelling for up to 12 months. This may be due to the problems outlined above or due to being too active on the knee before all the inflammation has settled.
All people will get some degree of numbness on the outer side of the knee but this usually resolves within a few months. Some people may have a persistent numb patch but this is usually not too troublesome.
In summary, TKR is a successful operation for the osteoarthritic knee. Good outcomes require a well motivated patient with good knee movement. The initial 3 months may be difficult but worth the effort.