The main reason for revision of a knee replacement is the loosening of old implants which can occur slowly over years, with the prosthesis hip joint becoming increasingly painful over time.
All forms of knee replacement surgery have a finite lifespan. The chance that a total knee replacement lasts 15 years is 85% and a unicompartmental knee is 60 to 80%.
Why does a Knee need to be revised?
- Pain is the primary reason for a revision. Usually the cause is clear but not always. Those knees without an obvious cause for pain, in general, do not do as well after surgery.
- Plastic (polyethylene) wear is one of the easier revisions where on the plastic insert is changed.
- Instability which means 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 you must have your joint followed up for life as there can be changed which show on XRay that indicate that the knee should be revised despite not having any symptoms.
- Infection usually presents as pain but may present as swelling or an acute fever.
- Osteolysis (bone loss) can occur due to particles being released into the knee joint which results in bone being destroyed.
- Stiffness is difficult to improve with revision but can be helped with the right indications.
Revision knee replacement procedures are very variable, depending on the problem and the requirements of the operation. In general, revision is complex and technically more demanding than ‘first time’ knee replacements and is associated with a higher risk of complications. Revision knee replacement often involves the removal of failed implant(s) and insertion of new components.
Revision total knee replacement takes longer than a standard total knee replacement and has a slightly higher complication rate. The prosthesis may also not last as long as a primary knee replacement.