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Partial knee replacement surgery

Description

A partial knee replacement is surgery to replace only one part of a damaged knee. It can replace either the inside (medial) part, the outside (lateral) part, or the kneecap part of the knee.

Partial knee replacement may also be called:

  • Partial knee arthroplasty
  • Unicompartmental knee replacement

Who should have a partial knee replacement?

Partial knee replacement may be a good choice if you have arthritis in only one side or part of your knee and:

  • You do not have very bad arthritis on the other side of the knee or under the kneecap (patella)
  • You have good range of motion of your knee
  • You have only minor deformity of your knee
  • You are older, thin, and not very active
  • Your knee ligaments are good

Most people with knee arthritis have damage to most of their knee joint. They have a surgery called total knee arthroplasty (TKA). This means the entire knee joint is replaced.

Otherwise, the reason to do partial knee replacement is the same as the reason to do total knee replacement.

Your new knee joint

Two surfaces of the knee joint are replaced on either the inside or the outside of your knee, not on both sides:

  • Lower end of the thighbone. This bone is called the femur. The replacement part is usually made of metal.
  • Upper end of the shin bone, the large bone in your lower leg. This bone is called the tibia. This replacement part is usually made of metal and a strong plastic.

Some orthopedic surgeons use some other materials. Some of these are metal on metal, ceramic on ceramic, or ceramic on plastic.

What happens during surgery?

You will not feel any pain during surgery because you will receive anesthesia, medicine that blocks pain. You will have one or a combination of 2 types of anesthesia:

  • General anesthesia. This means you will be unconscious and unable to feel pain.
  • Regional (spinal or epidural) anesthesia. Medicine is put into your back to make you numb below your waist. You will also receive medicine to make you sleepy if you have this type of anesthesia.

After you receive anesthesia, your surgeon will make an incision (cut) over your knee to open it up. This cut is often 3 to 5 inches long. Your surgeon will:

  • Look at the entire knee joint. If there is damage to more than one part of your knee, you may need a total knee replacement. Most of the time this is not needed, because tests done before the procedure would have shown this damage.
  • The damaged bone is removed and replaced with an implant (prosthesis) made of plastic and metal.
  • The thigh and shin bone may be slightly reshaped to fit the implant.
  • Once the implant is in the proper place, it is secured with bone cement.
  • The wound is closed with stitches.

This surgery usually takes up to 2 hours. This does not including preparing you for surgery beforehand and waking you up from anesthesia.

Most people go home the same day or the day after partial knee-replacement surgery. You can put your full weight on your knee right away. Recovery is quicker and less painful than after a total knee replacement. Most people do not need to stay in a skilled nursing center to continue to recover and receive physical therapy after this surgery.

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Review Date: 8/9/2018

Reviewed By: C. Benjamin Ma, MD, Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery, San Francisco, CA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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