Unicompartmental knee arthroplasty

Definition

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

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

See also: Total knee replacement

Alternative Names

Partial knee replacement; Knee replacement - partial; Unicondylar knee replacement; Arthroplasty - unicompartmental knee; UKA

Description

You may receive either general anesthesia (asleep, no pain) or local anesthesia (awake but no pain). The surgeon will make a small cut about 3 inches long over the knee that is damaged.

The damaged bone is removed and replaced with an implant (prosthetic) made of plastic and metal. The thigh and shin bone may be slightly 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.

The operation takes about 1 - 1 1/2 hours.

UKA has gone under significant changes since first performed in the 1970s. Today, the procedure offers many benefits over total knee replacement, including:

• Smaller surgical cut. The cut used in UKA is about 2 - 3 times smaller than the one required for total knee replacement. A smaller cut means less blood loss, less tissue damage, and a faster recovery.
• Better range of motion after surgery.
• Shorter hospital stay.
• Cheaper procedure. UKA costs about half that of total knee replacement.
• If needed, the implant can be easily converted to a total knee replacement.

Pain relief is the same for both procedures.

Risks

Risks for anesthesia include:

• Problems breathing
• Reactions to medications

Risks for any surgery include:

• Bleeding
• Infection

Risks for UKA include:

• Deep vein thrombosis
• Fluid build-up in the knee joint
• Implant failure
• Nerve and blood vessel damage
• Pain with kneeling
• Reflex sympathetic dystrophy (rare)