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Partial knee replacement

(Unicompartmental knee replacement)

Why partial knee replacement?

If the arthritis involves only one part of the knee joint, partial knee replacement can be a suitable option. This can be the case in approximately one out of every four or five patients with knee arthritis. If the rest of the knee is good at the age of 70, it may last you for life and a partial knee replacement may be sufficient.

What are the benefits of partial knee replacement?

As it is somewhat smaller operation than a full knee replacement, the risks are less. It has been shown in literature that major risks such as infection, clot in the leg or in lungs and risk of death is one third than that of total knee replacement. In addition the recovery is quicker and the knee feels “near normal”. A larger proportion of patient with partial knee replacement rate the new knee as excellent or good than patients with total knee replacement. Also on average, more patients with partial knee repalcement can return to higher activity level.


What are the risks of partial knee replacement?

Failure rate of partial knee replacement is higher than total knee replacement. In simple terms, if 100 patients underwent partial knee replacement, 6-8 may need a re-do operation after 10 years as compared with about 2-4 patients at 10 years after a total knee replacement. However, the re-do operation after partial knee replacement may be simpler (like first time total knee replacement). Re-do operation after a total nee replacement tends to be more complex.

In addition to risks of knee replacement, there is a small risk of fracture at the time of partial knee replcement or soon after the operation.

After 5-7 years following partial knee replacement, a small proportion of patients can develop discomfort in the knee due to increasing arthrhritis in the other parts of the knee.



What are the other options?

If you have exhausted non operative methods for knee arthritis and tried steroid injection, you may benefit by operation. Total knee replacement is a good option for pain relief in knee arthritis and majority of the patients are happy with improvement in pain as well as function following operation. In some cases with mild to moderate arthritis, high tibial osteotomy can be an option after careful consideration.

What does the operation involve?

A cut is made on the inside of the knee and small piece of the top of shin bone (tibia) is removed. A small spacer is then use to align leg and help remove small piece from the thigh bone. The cut surfaces anre then finished to match appropriate size of implant and a check is made to ensure proper fit and range of movement. Final implants are then cemented in position and wound is closed.


Recovery is similar to total knee replacement but quicker. Give yourself six weeks to get back to your daily activities and two to three months to return back to work.