What is a revision knee replacement?
This means that part, or all, of your previous knee replacement needs to be revised. This operation varies from very minor adjustments to massive operations replacing significant amounts of bone. Therefore, a standard procedure is difficult to describe in full.
A knee replacement consists of a femoral component, a tibial component, a plastic insert in between, and usually, but not always, a patella replacement.
Why does a knee need to be revised?
- Pain is the primary reason for revision. Usually, the source of the pain is clear, but not always. In general, the more obvious the source of pain, the more effective the surgery will be.
- Plastic (polyethylene) wear. This is an easier revision, where only the plastic insert is changed.
- Instability, meaning the knee is not stable and may be giving way or not feel safe when you walk.
- Loosening of either the femoral, tibial or patella component. This usually presents as pain but may be asymptomatic. It is for this reason why you must have your joint followed up for life as there can be changes on x-ray that indicate that the knee should be revised despite having no symptoms.
- Infection is usually presented through pain but may present as swelling or an acute fever.
- Osteolysis (bone loss). This can occur due to particles being released into the knee joint which results in bone being destroyed.
- Stiffness may be difficult to improve with revision but can help in the right situations
- X-rays are essential and should be of good quality, showing most of the femur and tibia
- Routine blood tests, especially to rule out infection
- Bone scans can help to determine if a component is loose
- Aspiration of the joint is occasionally done to diagnose or rule out infection
What is involved?
It will be explained to you prior to surgery what is likely to be done but in revision surgery the unexpected can happen and good planning can prevent most potential problems. The surgery is often, but not always, more extensive than your previous surgery. The surgery presents similar complications but at a higher rate than the first operation (see complications section in total knee replacement).
The knee is opened up and the problem identified. One or all of the components are removed, the bone surfaces cleaned up and new components inserted. Often augments are required to build up any bone loss or on occasion allograft (cadaver) bone may be required.
Again, this is similar but often a bit slower than the first knee replacement. Occasionally a brace may need to be worn. The range of motion may not be as good as a routine knee replacement.