A Unicompartmental replacement is a particular type of replacement where only one side of the knee (one compartment) is replaced. Use is therefore limited to those patients whose arthritis only affects one side of the joint, generally only the medial side (the inner side) of the knee. There are a number of other factors that need to be analysed before considering a Unicompartmental Knee Replacement.
In the right circumstances, a Unicompartmental Knee Replacement will provide a more normal feeling knee with a greater range of motion than a Total Knee Replacement. The other advantages include a smaller incision and a more rapid recovery.
As with any joint replacement, this is a major procedure and the decision to undertake surgery should only be considered if non operative measures have been unsuccessful in alleviating pain sufficiently.
The operation and Recovery
The operation is performed through a relatively small incision to the side of the kneecap (patella). A small amount of bone and residual cartilage is removed accurately using special instruments from the inner (medial) side of the knee, leaving the remainder of the knee, including ligaments and cartilage intact. The implant consists of a strong metal and polyethylene (a type of plastic) device, which essentially resurfaces the worn out side of the knee.
Walking and bending the knee are begun on the day of surgery, or on the first post operative day. Pain relief is provided with local anaesthetic for the first 48 hours followed by oral painkillers.
Expect to require painkillers for some weeks in order to minimise discomfort and allow exercises. Recovery generally takes 2 to 3 months, although further strengthening and conditioning will see improvements over 12 months.