New Total Knee Replacement Available

New York, NY—June 6, 2001

A new ceramic total knee replacement is now available after two years of clinical trials at Hospital for Special Surgery. The new knee offers relief to younger patients in their late 40s-early 50s who need total knee replacements.

There are more replacement operations performed on the knee than any other joint in the body. While more than 209,000 people - mostly over age 65 - have total knee replacements each year, 27% of patients are in the age range of 18-64 -- and that percentage is growing. Previously, many patients in their early 50s or younger had been warned not to undergo this surgery since normal use and wear offered a shorter life expectancy for the knee. This resulted in the need for more surgeries as patients grew older while their bones grew weaker.

"Unfortunately, we are seeing more and more patients with severe arthritis earlier in life; often the result of athletic injuries in their teens, 20s and 30s. Until now, these patients were advised to postpone the replacement surgery and deal with the pain. This new ceramic knee will offer dramatic pain relief to patients in their late 40s and 50s and will hopefully last much longer," said Dr. Richard Laskin, Chief of the Arthroplasty Council at HSS.

What Makes the Ceramic Knee Different?

The knee replacement prostheses that have been used for over the past twenty years are made of a plastic tibial component and metal (cobalt chrome alloy) femoral component. It is estimated that these knees last about 15-20 years. The new ceramic knee consists of a plastic tibial component and a metal (zirconium alloy) with a ceramic surface femoral component with a life expectancy of 20-25 years.

Life expectancy of the replacement is based on the wear of the joint, which is a result of the tibial and femoral components rubbing against each other. By changing the surface of the femoral component from metal to ceramic, the studies have shown that the wear is many times lower than that seen with the traditional cobalt chrome alloys rubbing against plastic. A lower wear rate means that the implant has a longer potential life expectancy.

Other advantages of the ceramic knee are:

• It is scratch-resistant, whereas cobalt chrome alloy can develop small microscopic scratches in the body. These scratches, when rubbing against the plastic tibial component, can cause even greater wear.

• An oxidized ceramic surface is more "wettable", making for a smoother articulation with the plastic. This too leads to reduced wear rates.

• The material is extremely biocompatible. There are some patients who have allergies to nickel, which is a constituent of the cobalt-chrome type of alloys that are traditionally used for total knee components. As a result, patients with severe allergic reactions to nickel were unable in the past to receive total knee prostheses. The oxidized ceramic surface zirconium alloy implant contains no nickel, so it can be safely used for these patients.