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Hip Implants Get The Active Back In Gear

Posted - Jun. 24, 2003 at 6:20 a.m.



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The pain of an arthritic hip forced then-42-year-old Alec Danz to give up jogging, hiking and biking. As the disease progressed, Danz lost more and more of the cartilage that cushions the hip joint.

''I couldn't sleep at night because of the pain,'' he says.

A decade ago, surgeons would have told Danz to hold off on surgery to replace the diseased hip because they worried that an artificial hip would wear out quickly in younger, more active people.

But now many surgeons are quick to recommend one of two types of a new artificial hip -- both slightly different versions of the hip joint made of smooth ceramic.

The advance comes just in time for aging but active baby boomers. Many experts believe high-impact sports such as jogging and skiing may accelerate the aging-related wear on the cartilage. In the coming decades, more boomers will experience hip pain that might drive them to consider an artificial hip.

Some orthopedic surgeons believe the new implants will revolutionize treatment by allowing patients to maintain an active life.

''The hope is these new hip implants will last 20 years or longer,'' says William Jaffe, an orthopedic surgeon at New York University.

About 20 million Americans have osteoarthritis, a degenerative disease that often occurs in the hip joint. The disease, which typically affects older people, occurs when the cartilage at the ends of the bones starts to wear thin.

Both designs use ceramics

The Food and Drug Administration in February approved two newly designed hip implants, both made of a durable ceramic. Danz got his artificial hip more than two years ago as part of a study that led to the approval.

''I am active, pain-free and happy once again,'' Danz says.

The 44-year-old doctor's assistant says he bikes 100 miles a week, swims and hikes.

Last September, Danz scaled Mount Kilimanjaro, the tallest peak in Africa. It took seven days -- an average time for most climbers -- to get to the top, Danz says. He says he had no problems with his artificial hip.

The artificial hip replaces the worn-out ball-and-socket hip joint.

In a 90-minute operation, surgeons remove the diseased joint and insert the artificial hip. Patients stay in the hospital for about four days and can resume usual activities in about six weeks.

Two companies -- Stryker Howmedica Osteonics and Wright Medical -- make the new ceramic implants, which consist of a ceramic ball that fits into a ceramic-lined socket. The standard hip implant consists of a metal ball and plastic socket.

In the past, surgeons routinely offered the standard implant to senior citizens who had a painful arthritic hip. Many seniors just wanted to walk to the mailbox and back, says David Blaha, an orthopedic surgeon at the University of Michigan.

But many patients today consider the artificial hip at a younger age. ''They expect a more active lifestyle,'' says Andrew Urquhart, also of the University of Michigan.

Both surgeons routinely offer the ceramic hip replacement to their younger patients.

Surgeons have been reluctant to do a hip operation on a 40- or 50-year-old: The standard implants lasted about 15 years, and surgeons worried that active younger people would need a second and possibly third operation.

Each additional operation becomes more difficult, raising the risk that the implant won't last, Urquhart says.

But research on the ceramic hips suggests they'll last at least five years longer than traditional metal and plastic implants. Experts know that when the metal ball and plastic socket rub together, the friction produces a fine plastic dust, and the leg bone attached to the artificial implant eventually wears down. That erosion can weaken the artificial joint.

Time will tell

Studies suggest that the ceramic implants produce far less debris, less than 1 micron of dust each year. A standard metal-and-plastic hip produces up to 200 microns of dust.

Less debris means the new implants should, in theory, wear less and last longer. Of course, the ceramic hips haven't been around long enough to know whether they'll outlast the metal-on-plastic hips.

Jaffe and his colleagues studied about 500 people, of which two-thirds got the new ceramic hip. Five to six years after the patients received the hip, the team found no evidence of wear or breakage, a finding that helped get the implants on the market.

''We don't see any sign of early wear,'' Jaffe says. In contrast, the standard implants can show signs of wear at five years, he says.

Study findings like these are far from definitive, says John Klippel, medical director of the Arthritis Foundation in Atlanta. Although the early findings on the ceramic hip are promising, no one knows how patients like Danz will fare over the long run, he cautions.

''The challenge is dealing with younger patients,'' Jaffe says. Six months after the operation, patients may be tempted to take up jogging or other high-impact sports that may damage the new hip, he says.

Danz may be cycling and hiking, but he has given up jogging on the advice of his doctor. Even so, he's taking a chance that his active lifestyle eventually will wear out the new hip.

To Danz, that's a risk worth taking: ''This is a big part of who I am.''

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© Copyright 2003 USA TODAY, a division of Gannett Co. Inc.

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