The knee can be divided into three joints; medial or inside, lateral or outside and patello-femoral or kneecap joint. If the kneecap alone is affected by arthritis then an artificial joint can replace this part.
There are advantages of a patella replacement over a full knee replacement in that there would be a smaller incision, less post-operative discomfort, quicker recovery, a better range of motion and the retention of your own main knee joint.
Knee cap replacement surgery is carried out in hospital under general anaesthetic and local anaesthetic is injected into your knee at the end of the operation so you wake up with no pain. You would normally be admitted the evening before the operation if your operation is in the morning or early on the day if your operation is scheduled for the afternoon or the evening. This allows you time to settle in and be prepared.
You will not be able to eat for eight hours prior to surgery although you will be able to drink small amounts of water up to four hours before.
The operation itself takes around 60 minutes and your surgeon will make a small cut down the front of your knee. The kneecap is removed and replaced with an Avon patello-femoral artificial joint and the incision is closed with stitches or clips. An acrylic cement is usually used to bond the new joint directly onto your bones.
Afterwards your knee will be tightly bandaged to help minimise swelling and fine drainage tubes may also be left in for up to 48 hours.
You are likely to stay in hospital for three to four days after the operation and your physiotherapists will give you exercises that help you walk the day after the operation. You will gradually progress from using crutches to using walking sticks and you will be allowed to go home once you are fully weight bearing and can manage stairs and to care for yourself.
The knee dressing can be peeled off easily ten days after the surgery and, as the stitches are internal, they do not need to be removed. You will be given a cold compress or 'Cryocuff' along with instructions on how to cool your knee, which is important and aids recovery. You will see your consultant once again six weeks after your operation to review your progress.
Patella surgery recovery is moderate and reasonably quick. You are likely to need four to six weeks off work and driving following the operation.
Kneecap Replacement surgery is a relatively new procedure which has given good results to date with the promise of a long lasting solution to this particular problem. There are some potential complications you should be aware of. These only affect less than 4% of patients.
- Infection can occur although our theatres have ultra-clean air operating conditions keeping infection rates at 1-2%.
- Blood clots are possible in any major joint replacement surgery but again are in the 1-4% category and have well established treatments including aspirin.
- A small patch of numb skin can be present on the outer part of the knee near the kneecap, this will improve over time.
- The knee will have some stiffness after the operation although we are aiming for 0-125 degs of movement once things have settled down.