A study on HR -THR

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Doubts Raised Over New Type of Hip Surgery
June 4th 2009 Wall Street Journal

By ANNE TERGESEN

Hip resurfacing, an increasingly popular alternative to total-hip-replacement surgery, has been touted as a better way for younger, more-active people to replace arthritic hip joints. But even as baby boomers head into their prime years for such procedures, enthusiasm for the technique appears to be waning in the medical community.

Some surgeons say they are reassessing the advisability of hip resurfacing. Some recent studies, among the first to put the procedure to rigorous scientific testing, have shown that hip resurfacing was no better than the newest types of total hip replacement at helping patients resume an active lifestyle. Other studies have highlighted a potential problem with resurfacing: Women are more likely to suffer complications, including a need for corrective surgery, following a hip resurfacing than a total joint replacement.
Under The Knife

Surgeons say hip resurfacing isn't right for all patients.

* Some studies show resurfacing can boost the chances of bone fractures in women.
* The procedure is best suited for young people with strong bones, doctors say.
* New, more-durable implants for total hip replacements have made that procedure more reliable.

"We were doing a lot more hip resurfacings two to three years ago," says Martin Lavigne, a surgeon at Maisonneuve-Rosemont Hospital in Montreal and a co-author of one of the recent studies. With the introduction in recent years of more durable implants for total hip replacements, "the functional outcome [of the procedures] is the same." But with resurfacings "the risks of complications are greater," he says.

HR
To do a hip replacement, a surgeon cuts away the top two inches of the thigh bone, or femur, and replaces the hip's socket and ball with prostheses. The artificial ball is secured by a rod inserted into the femur.

THR
With a hip resurfacing, the surgeon replaces the socket but preserves the patient's femoral ball, or head, smoothing away the arthritic damage before capping the bone like a tooth.

Though seemingly a less-drastic operation, a hip resurfacing is typically more difficult to perform than replacing the total joint. In general, surgeons say, resurfacings can take longer and require bigger incisions than total hip replacements. And because the surgeon retains the femoral ball, it's often harder to get an unobstructed view of the socket -- making it trickier to properly position the implant.

Some surgeons say resurfacing can still be the better option for certain patients, especially younger and more-active people who might wear out a total hip replacement. Because resurfacing removes less bone than a full joint replacement, the procedure leaves more bone for surgeons to work with should the patient require a second operation.

Case by case
Edwin Su, an orthopedic surgeon at New York's Hospital for Special Surgery, says he assesses patients on a case-by-case basis, often advising resurfacing for people who are younger and with stronger bones. Frequently, those patients are men. But, he says, "I have quite a few female patients. I do think the window for female patients is smaller. We usually want them to be after child-bearing [age] but before menopause so their bone quality is good."

To be sure, hip surgery of any type is often difficult. Patients can generally expect to be hospitalized and then be on crutches for at least a few weeks. Physical therapy might go on for a couple of months. Both types of surgery expose small numbers of patients to the risk of complications, including a possible fracture, dislocation, or even leg lengths that don't match.

Hip resurfacing became widely available in the U.S. in 2006. Since then, the number of procedures has increased to nearly 5%, or about 13,000, of the 270,000 first-time hip surgeries performed last year, according to Millennium Research Group, a research and consulting firm. Medicare and most private insurers generally cover the cost of hip resurfacings or total hip replacements, which can each cost between $30,000 and $50,000, depending on length of hospital stay and other factors.

Self-proclaimed "surface hippies" -- who congregate in Web sites dedicated to hip resurfacing -- say the procedure has allowed them to return to preferred routines and exercise regimens.

"Within six months, I was doing everything I was doing before," says Jim Roxburgh, 51, of Wilton, Calif. Mr. Roxburgh, a hospital executive, says he bikes as many as 200 miles a week, swims about three miles a week, and spends about two hours a day in a martial-arts studio.

Study 1 - HR successes
Several studies have backed the notion that patients with resurfaced hips are able to do more than those with traditional full hip replacements. One study, published in 2008, tracked two groups of 54 patients -- one with resurfacings and the other with full hip replacements using a conventional implant. At an average of 40 months after surgery, the resurfacing patients had significantly higher activity scores than those with conventional replacements.

The study's co-author, Michael Mont, director of the Center for Joint Preservation and Replacement at Sinai Hospital's Rubin Institute for Advanced Orthopedics in Baltimore, acknowledges the study had limitations. Because many resurfacing patients are more active before surgery, they are pre-disposed to greater activity levels afterward, he says. Still, Dr. Mont says he believes hip resurfacing can be a superior procedure for many people. He has found that resurfacing patients generally experience lower dislocation rates, a more normal gait and a greater range of motion.

More studies - about the same
In three recent studies, however, researchers found the functional outcomes of hip resurfacings and total hip replacement to be roughly the same. The studies randomly assigned patients to one of the two surgeries without disclosing which each had received.

Dr. Lavigne, the Montreal surgeon, says his study, slated for publication this summer, followed 48 patients -- 24 with hip replacements and 24 with resurfacings. Up to 12 months after surgery, the two groups scored comparably on various measures of activity, including gait speed and balance.

"The purported advantages of hip resurfacing with regard to higher activity levels are not true," Dr. Lavigne says.

A similar study of 107 patients at the University of British Columbia also found no difference in activity levels one to two years after surgery. Researchers did detect, however, that the blood streams of patients with total hip replacements had higher levels of metal ions. And preliminary unpublished data from a continuing study at the Mayo Clinic in Rochester, Minn., indicates that patients a year from surgery showed little "difference with respect to activity level, range of motion or speed of recovery," says Robert Trousdale, a surgeon at the clinic. Of some 30 patients enrolled in the study, half were randomly assigned to resurfacings, while the other half received full hip replacements.

The three studies compared resurfacing to a relatively new type of implant used in full hip replacements. These do away with the plastic commonly found in conventional implants, making them able to support a larger artificial ball that more closely matches the human anatomy. The newer implants are expected to last longer than the 15 to 20 years typical of a standard hip implant, but just how much longer isn't known.

Issue of HR in women
Other reports have raised concerns about the use of resurfacing in women. One study, by the Australian Orthopaedic Association, drew on data tracking the 135,799 first-time hip surgeries performed in Australia in the seven years ended 2007. Researchers found that five years after surgery, 5.2% of women under 55 with a resurfacing had undergone a second, corrective operation. But only 3.6% of the women in that age group needed a second operation after getting a full hip replacement. Among men, only those over 65 were deemed at higher risk of needing a corrective operation after a resurfacing.

Surgeons attribute the gender gap to the fact that women have smaller frames and, particularly after menopause, lower bone densities. This can raise the risk that, due to frail bones or misplaced implants, a patient will fracture the femoral neck -- a piece of bone surgeons retain in a resurfacing but replace in a full hip replacement.

Dr. Su, the New York surgeon, says the recent studies have not fundamentally altered his belief that hip resurfacing is of value for the right patients. Still, he says: "A lot of the excitement [for hip resurfacing] has been dampened because of the new reports coming out."
 
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