Partial Knee Replacement

Partial knee replacement, also called unicompartmental knee replacement simply means that only a part of the knee joint is replaced through a smaller incision than would normally be used for a total knee replacement.

Unicompartmental knee replacements have been performed since the early 1970’s with mixed success. Over the last 25 years implant design, instrumentation and surgical techniques have improved markedly making it a very successful procedure for unicompartmental arthritis. Recent advances allow us to perform this through smaller incisions and therefore the procedure is not as traumatic to the knee making recovery quicker.

Advantages

The big advantage is that if for some reason it is not successful or fails many years down the track it can be revised to a total knee replacement without difficulty.

Disadvantages

Not quite as reliable as a total knee replacement in taking away all pain long term results not quite as good as total knee

Candidates for Partial Knee Replacement Who is suitable?

Who is not suitable?

Surgical Procedure

Each knee is individual and knee replacements take this into account by having different sizes for your knee. If there is more than the usual amount of bone loss sometimes extra pieces of metal or bone are added.
Surgery is performed under sterile conditions in the operating room under spinal or general anaesthesia. You will be on your back and a tourniquet applied to your upper thigh to reduce blood loss. Surgery will take approximately two hours.
The Patient is positioned on the operating table and the leg prepped and draped.

A tourniquet is applied to the upper thigh and the leg is prepared for the surgery with a sterilizing solution.
An incision around 7 cm is made to expose the knee joint. Smaller incisions are made if the surgery is done using arthroscopy.
The bone ends of the femur and tibia are prepared using a saw or a burr.

Trial components are then inserted to make sure they fit properly.
The real components (Femoral & Tibial) are then put into place with or without cement.
The knee is then carefully closed and drains usually inserted, and the knee dressed and bandaged.

Post-operation Care

Usually you will remain in the hospital for 3-5 days. Depending on your needs, you will then return home or proceed to a rehabilitation facility. You will need physical therapy on your knee following surgery. You will be discharged on a walker or crutches and usually progress to a cane at six weeks. Bending your knee is variable, but by 6 weeks it should bend to 90 degrees. The goal is to obtain 110-115 degrees of movement. Once the wound is healed, you may shower. You can drive at about 6 weeks, once you have regained control of your leg. You should be walking reasonably comfortably by 6 weeks. More physical activities, such as sports previously discussed may take 3 months to be able to do comfortably.
When you go home you need to take special precautions around the house to make sure it is safe. You may need rails in your bathroom or to modify your sleeping arrangements especially if they are up a lot of stairs.

You will usually have a 6 week check up with your surgeon, who will assess your progress. You should continue to see your surgeon for the rest of your life to check your knee and take X-rays. This is important as sometimes your knee can feel excellent, but there can be a problem only recognized on X-ray.
If you have any unexplained pain, swelling, or redness or if you feel generally poor, you should see your doctor as soon as possible.

Risks and Complications

As with any major surgery, there are potential risks involved and may include:

Discuss your concerns thoroughly with your Orthopaedic Surgeon prior to surgery.

Uni Condylar Knee Replacement

This simply means that only a part of the knee joint is replaced through a smaller incision than would normally be used for a total knee replacement. The knee joint is made up of 3 compartments, the patellofemoral and medial and lateral compartments between the femur and tibia (i.e. the long bones of the leg).

Often only one of these compartments wears out, usually the medial one. If you have symptoms and X-ray findings suggestive of this then you may be suitable for this procedure.

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