News: Ceramic Revolutionizes Hip Replacement Surgery
Posted on June 29, 2003
By Gary Gately, HealthDay

Four months ago, Sal Dassaro's left hip had deteriorated so badly, he couldn't play catch with his sons. Or walk straight. Or climb two steps at once.

Now, Dassaro, 55, not only tosses balls with his two young children, he plays racquetball regularly. He's also walking straight now, and jogging again.

Gone is the pain that used to flash through his groin, and the numbness in his legs and ankles. And he no longer worries about stumbling on the gap between the railroad platform and the New Jersey Transit commuter train he takes several times a week to New York City.

Dassaro owes his new-found freedom of movement to a hip replacement he received in March. But he didn't get the standard replacement hip that has been used for decades. Instead, he received a new type that was approved by the U.S. Food and Drug Administration just about a month before his surgery.

Rather than the traditional replacement joint—; a metal ball and a plastic socket —the new technology uses ceramic-on-ceramic joint surfaces.

Dassaro, a furniture and office equipment sales executive, is just the sort of patient who'll benefit most from ceramic hips: graying baby boomers who want to maintain an active lifestyle.

“I feel 10 or 15 years younger,” says Dassaro, an Old Bridge, N.J., father of two boys, ages 8 and 11. “Having younger kids, I'm able to keep up with them for the most part, whereas if I didn't have [the hip replacement] done, there was no way.”

The human hip joint is known as a “ball-and-socket” because the head of the thigh bone, or femur, moves inside the cup-shaped hollow socket of the pelvis. A total hip-replacement implant consists of a stem, which fits into the head of the thigh bone and provides stability; a ball, to replace the head of the thigh bone; and a cup, to replace the deteriorated hip socket.

In older hip replacements, used in the United States since the 1960s, the metal ball would grind away the plastic cup. The joints tended to wear out in 10 to 15 years. This forced patients to undergo additional replacement surgery, says Dr. Steven Stuchin, director of orthopedic surgery at the Hospital for Joint Diseases of New York University Medical Center.

The life span of the metal-and-plastic joints is even shorter for younger, more active people as tiny particles can break off, leading to deterioration, Stuchin says.

“What we began to see is that, as people live longer and are more active, they put more demand on these joints,” Stuchin says. “They literally would wear out. So, the challenge became what could we do that wouldn't wear out?”

Ceramic-on-ceramic joints provide the solution, Stuchin says. They produce less friction, and laboratory test have shown they can last up to 200 times longer than the traditional hip-replacement joint component, he says.

FDA approval of the new ceramic-on-ceramic joints came after tests of the devices by two manufacturers: Wright Medical Group of Arlington, Tenn., and Stryker Corp. of Kalamazoo, Mich.

An orthopedic implant division of Stryker Corp. began clinical studies of ceramic-on-ceramic implants in 1996. The clinical trial consisted of 22 investigations at 16 sites with more than 1,100 patients getting the implants, the company says.

“This ceramic-on-ceramic system has been developed for the younger and more active patient populations who have demonstrated higher wear rates with conventional implants,” says Dr. James D'Antonio, associate professor at the University of Pittsburgh and one of the lead investigators in the clinical study.

The FDA recalled devices with ceramic-on-ceramic hip joints in 2001 because of a higher-than-expected fracture rate. But the ceramic used in joints made since then, called alumina, has been found to be better than the older type of ceramic, called zirconia, that prompted the recalls.

Stuchin began doing ceramic hip replacements in New York state after FDA approval of the joints and has done one or two a week since.

“The typical patient is somebody who expects to be quite active and throwing the ball with their kids and going out with their family,” Stuchin says. “People are expected to be in the game and in the swim, and our job is to help in that.”

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