The vast majority of knee replacements will never need reoperation. Due to improvements in prosthetic design and materials, and refinements in surgical technique, most knee replacements will survive longer than the patient in whom they are inserted.
A reoperation is called a revision. It might be considered for the following reasons:
- Plastic insert wear. The plastic might wear right down and need replacing. On occasion this is the simplest revision and nothing else needs to be done.
- Prosthesis Loosening or Bone Loss around the prosthesis. The main cause is the tiny particles of plastic and metal that get worn off the prosthesis surface with time. Our own scavenger cells mop up these particles but in the process some of the bone around the prosthesis weakens. Eventually, the prosthesis will lose bony support and loosen. There will usually be signs on an X-ray before symptoms of pain or swelling, so some X-ray surveillance of prostheses is generally recommended, for example after 10 years.
- Infection. A well-established infection might necessitate removal of the prosthesis in order to eradicate the bacteria responsible. Once the infection resolves, a revision is then possible.
- Severe Stiffness or Instability.
- Component malpositioning.
In general, a revision will provide a satisfactory outcome when a definite problem can be determined. Some patients with knee replacements will have pain without an obvious cause, and generally do not benefit from revision surgery.
During your consultation the risks and limitations, and the benefits of surgery will be discussed. Further preoperative tests are generally required and planning is considerably more complex than for a standard knee replacement.
The Operation and Recovery
The operation will be done via the previous incision, will take longer to perform and will usually require special prosthetic components to compensate for bone loss or ligament sloppiness.
The recovery process is surprisingly similar to that for a first knee replacement. However the chance of some residual pain or other limitation, like inadequate knee bend, is higher than with a standard knee replacement.