Unicompartmental knee arthroplasty

Alternative Names: Partial knee replacement; Knee replacement - partial; Unicondylar knee replacement; Arthroplasty - unicompartmental knee; UKA; Minimally invasive partial knee replacement

Unicompartmental knee arthroplasty (UKA) is surgery to replace either the inside (medial) or outside (lateral) compartments of the knee.

Because only one part of the damaged knee is replaced, it is often called a partial knee replacement.

See also: Total knee replacement

Description of Procedure

Partial knee replacement surgery involves removing damaged cartilage and bone in the knee joint. Man-made (artificial) pieces called prostheses are then placed in the knee.

You will not feel any pain during surgery because you will receive anesthesia, medicine that blocks pain. You will have one of these two 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 get medicine to make you sleepy if you have this type of anesthesia.

After you receive anesthesia, your surgeon will make a surgical cut over your knee to open it up. This cut is often 3 to 5 inches long. Then your surgeon will:

• Examine the whole inner knee area. If damage is found in more than one part of your knee, you may need a total knee replacement. Most of the time, however, this is not needed.
• The damaged bone is removed and replaced with an implant (prosthetic) that is made of plastic and metal.
• The ends of the thigh and shin bone will be cut and shaped to fit the implant.
• Once the implant is in the proper place, it is secured with bone cement and the wound is closed with stitches.

Risks of Unicompartmental knee arthroplasty

Risks for anesthesia include:

• Problems breathing
• Reactions to medications

Risks for any surgery include:

• Bleeding
• Infection

Risks for UKA include:

• Blood clots
• Fluid buildup in the knee joint
• Implant failure
• Nerve and blood vessel damage
• Pain with kneeling
• Reflex sympathetic dystrophy (rare)

Knee joint	The structure of a joint	Partial knee replacement - series

Review Date: 12/20/2010
Reviewed By: C. Benjamin Ma, MD, Assistant Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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