Unicompartmental Knee Replacement

What is the point of replacing only half of the knee?

There has been a change in attitude amongst surgeons in the last few decades. The old, aggressive surgical practices of big operations with big incisions has been replaced by minimally invasive techniques and a philosophy of doing the smallest amount possible to achieve a result.

A good example of this is cartilage tears in the knee. The old way was a large incision and complete removal of the meniscus. Today only the torn part is removed and this is done as a day case via key hole surgery.

Knee replacements are the same. Surgeons began to ask: "Why are we replacing the whole knee when only one compartment is worn?"

Due to the angulation that occurs in arthritis - either bow-legged or knock-kneed - all of the weight goes on the worn half of the knee while the other half gets a rest. This means it is often in very good condition.

Half knee replacements are only suitable if there is a good enough surface on the less worn side of the knee.

One of the advantages of unicompartmental knee replacements is that you can still have a full knee replacement later. It is more difficult to perform but not as troublesome as a revision total knee replacement.

There have been some concerns over the lifespan of half knee replacements. It has been argued that their shorter life is a result of them being used on much younger people who demand more from the implant.

There are many factors to consider, so discuss your personal medical history with your consultant to see if a unicompartmental knee is the right choice for you.

Why do Knee Replacements hurt more than Hip Replacements?

Although not always the case, most people who have had both a knee and hip replacement report that the knee is the more painful.

There are a few reasons for this, the main one being the location of the incision.

There are multiple ways of approaching a hip replacement but all of them result in the incision being 'out of the way'. A knee replacement has the incision straight down the front of the knee. This has an effect on the rehabilitation.

To prevent the knee from stiffening, the knee must be quickly exercised. This means bending the knee and stretching the skin around the incision. This is responsible for a lot of the post-operative pain. After a hip replacement, you are not required to do movements that stretch the scar, in fact you are told to avoid them.

This is why I tell people you can be a little lazy and do OK after a hip replacement, but to get a good result from a knee replacement, you are going to have to work. The pain is something that gets in the way but should be seen as a temporary obstacle to years of pain free walking.

You should be going into a knee replacement operation focused and motivated. It will be a few weeks of toil for the greater good. I have always found that those who have put up with the pain of an arthritic knee for years manage with ease. At least this pain is because of an operation that is going to help. That is much easier to deal with than the pain of arthritis that gains you nothing.