MUHC takes lead in knee replacement technology

University of Missouri Health Care has been named the lead investigational center in a newly-approved Food and Drug Administration (FDA) clinical trial studying new technology in knee replacement surgery.

On the morning of Feb. 22, 2001, B. Sonny Bal, M.D., an orthopaedic surgeon and joint replacement specialist at MUHC, became the first physician in the FDA study to implant a ceramic (zirconia) femoral component into a patient during a total knee replacement (TKR) procedure.

"This may be of interest to knee replacement candidates because the ceramic materials used in the bearings of artificial hip and knee replacements have demonstrated less wear, which could result in a longer lasting implant," said Bal.

Traditional knee-replacement surgery has been performed for decades, using a cobalt-chrome (metal) component attached to the end of the femur (thigh bone). This part slides against a polyethylene (high density plastic) layer, which is anchored to the tibia (leg bone). The knee cap is resurfaced with polyethylene as well. Over time, however, the metal-polyethylene interfaces in the artificial joint and generates microscopic wear particles. This process ultimately leads to the loosening of the prosthetic parts, requiring repeat surgery.

The alternative bearing surface used in the MU study is zirconia ceramic, which offers a much smoother surface than cobalt-chrome. A smoother surface results in less wear, and is expected to contribute to a longer-lasting knee replacement. The new device has been developed by Encore Orthopaedics, Inc., of Austin, Texas.

"The benefit to this technology will hopefully be seen in the patient's future when the components are still going strong, long after one would expect them to fail," Bal said.

Participation in the study is offered to any patient who is a candidate for TKR surgery and who meets the inclusion/exclusion criteria. The procedure is exactly the same as if a metal femoral component were used, and postoperative rehabilitation and recovery should be identical to what is associated with traditional surgery.