Medial Knee replacement

Partial knee replacement - medial unicompartmental knee replacement

What is a medial partial knee replacement?

The knee is made up of the femur (thigh bone) sitting on the tibia (shin bone) with the patella (knee cap) resting on the front of the femur. Arthritis means that the cartilage that covers the end of the bones is worn out, exposing the bone underneath. When the worn out parts of the joint move against each other, they can cause pain.

Arthritis may affect only the inner half of the knee joint while the rest of the knee remains normal. In this situation, a medial partial knee replacement may be appropriate. In this operation, only the inner half of the knee is replaced. The normal parts of the knee are left intact.The surgeons at Melbourne Hip and Knee have extensive experience with the medial unicompartmental knee replacement including training for a year in Oxford with the developers of the world's most successful unicompartmental knee replacement, the Oxford Partial Knee Replacement.

What is the advantage of a partial knee replacement over a total knee replacement?

The advantage of a partial knee replacement is that the operation is less invasive and the recovery is faster. Movement of the knee can feel more normal after a partial knee replacement, as compared with a total knee replacement, because the natural ligaments are not removed.

How is a medial partial knee replacement performed?

The surgery is performed under an anaesthetic. An incision is made in the front of the knee and the knee joint is exposed. The ends of the femur and tibia on the inner half of the knee are cut and shaped. The replacement prostheses are then implanted. The wound is sutured closed.

What is the recovery like after the operation?

You will stay in hospital for 3-5 nights. You will be able to walk on the operated side straight away, although you may need crutches for support for a couple of weeks. You should begin to bend and straighten the knee immediately after the operation. Physiotherapy will begin while you are in hospital. If you are progressing well in hospital you will be discharged directly home. If you require more time, you will be transferred to a rehabilitation hospital for 1-2 weeks.

You will need 3-4 weeks off work and longer if your job is physically demanding.

You will require physiotherapy to help you regain your strength and range of movement. It often takes six months before the knee feels normal an it will keep improving over twelve months.

What are the complications associated with a partial knee replacement?

As with any operation, there is a small risk of heart attacks, strokes and breathing problems associated with an anaesthetic. You will be assessed before your operation to see if anything needs to be done to decrease the chance of these complications occurring.

There is a risk of infection, which occurs in about 1 in 100 patients. If you develop a serious infection, you may require further operations to wash it out. If this is unsuccessful, we may need to remove the prostheses and start again after the infection has been treated. To minimise the risk of infection, you will be given antibiotics during and after the operation.

There is a small risk of nerve or vessel damage. It is expected that you will get a patch of numbness on the outer side of your knee, which will be permanent to a degree.

If you lose a lot of blood, you may need a blood transfusion.

There is a risk of developing clots in the legs, which can travel to the lungs. To minimise the chance of this happening, you will be given blood thinners for 4-6 weeks after the operation. You will be given pressure stockings, which you should wear during this period.

Over time, there is a risk of the knee replacement wearing out or loosening. If this happens, you may need a revision or redo operation. Most partial knee replacements last at least 20 years.

If you have any other questions or concerns, please ask your surgeon.