November 7, 2008
Even as patients in this country continue to undergo an increasingly popular alternative to traditional hip replacement surgery, medical researchers both here and abroad are raising warning flags about the technique’s use in women.
Makers of artificial joints and some American doctors have aggressively promoted the technique, known as hip resurfacing, since it became available in the United States in 2006, several years after it went into use overseas.
The procedure is aimed at middle-age patients, who are physically active and are expected to outlive the normal 15-to-20-year life span of a full replacement joint. Because hip resurfacing preserves more of a patient’s own thigh bone than conventional full hip replacement, proponents say patients who undergo it will be better able to tolerate subsequent replacement surgery.
But studies from some countries where resurfacing has been used longer than in the United States, including Sweden and Australia, have repeatedly shown a higher failure rate for women who undergo the procedure than for men. Such women are more likely to need a second corrective operation soon after the first, compared with women who get a conventional full replacement hip, a recent British study found.
And earlier this week, researchers released a study of resurfacing patients in the United States that raised similar cautions. The study, conducted by researchers at Rush University Medical Center in Chicago, indicated that complications from hip resurfacing were more frequent in women — of all ages — and in men over 55.
“This procedure is not ideal for everyone,” said Dr. Craig J. Della Valle, who led the Rush University study. Dr. Della Valle noted that data showed that resurfacing worked very well in men under 55.
The potential problems with resurfacing reflect a drawback of which doctors have been long aware. Although hip resurfacing has the advantage of retaining more of a patient’s thigh bone, that bone must remain strong for years.
That is the reason the procedure already is not advised for patients in their 60s, male or female. But the drawback may also be potentially significant for even younger women, because of the bone weakening that accompanies menopause. Meanwhile, even advocates of resurfacing acknowledge that they have yet to agree on how best to screen women for the procedure.
So far, though, there has been no sign that the procedure’s use is slowing among patients in this country, where thousands of women are expected to have the surgery this year. Several surgeons who performed resurfacings on hundreds of patients over the last three years said that almost all of them were doing well. Still, two of those doctors said that the few failures that they had seen in female patients occurred in women in their late 50s or early 60s.
The Rush findings were based on a review of short-term outcomes for the first wave of patients in this country to receive a resurfacing device made by Smith & Nephew. The device, known as the Birmingham hip resurfacing system, was approved for sale here by the Food and Drug Administration in 2006.
The study found that 32 of the first 537 hip resurfacing patients to get the device after its approval, or about 6 percent of them, suffered serious complications in the first year after the procedure. In 14 of those cases, corrective surgery was necessary. The most frequent cause was bone fracture of the femur, a problem that occurred in four of the some 160 female patients reviewed. All four patients were between the ages of 42 and 59. A study released in September by the Royal College of Surgeons of England found that 3.7 percent of the 2,360 women who underwent resurfacing in England had to have a second operation to repair the same hip within three years. That compared with a rate of follow-up surgeries of 1.6 percent or less for women who got traditional hip replacements.
Dr. Della Valle at Rush said that although he was an advocate of the procedure, he urged caution in its use in women and older men.
“We have to be careful both on the patient side and the doctor side about adopting new technologies,” he said.
The problems with hip resurfacing in some women first emerged in places like Australia, Sweden and England that operate databases, known as registries, which regularly track the outcomes of orthopedic procedures and are publicly available. The United States does not have such a national tracking system.
In recent years, even as hip resurfacing gained popularity here, some orthopedic specialists refused to perform it in any patient, male or female, citing a lack of long-term data about its durability. The rate of problems seen in short-term studies like the one at Rush typically increases over time.
With traditional replacement hips, “based on data, I know what the results will be in 10 to 20 years,” said Dr. Thomas P. Sculco of the Hospital for Special Surgery, in Manhattan, who performs only traditional replacements. “I can’t give you 10-to-20-year data for hip resurfacing.”
In a traditional hip replacement, the upper end of the thigh bone, or femur, is removed and replaced with a prosthesis. In a hip resurfacing, a greater portion of the femur is saved, with an artificial cap placed over the head of the femur. Many men and women say they are pleased with the procedure’s results. But when failures occur, it is because a patient’s bone is not strong enough to support the device or because of surgical error.
Dr. Jan H. van der Meulen, the researcher who headed the English study, said recently that its results suggested that doctors should limit the procedure to men “unless other factors come into play.” The leader of Sweden’s orthopedic registry, Johan Karrholm, said in a recent interview that his organization was recommending that resurfacing be used on female patients only in clinical research studies.
In the United States last year, resurfacing represented only a small fraction of the 430,000 hip replacements that occurred — perhaps 10,000 to 15,000 cases. But the number of new resurfacing patients this year is expected to grow by 40 to 50 percent, according to the consulting firm Millennium Research Group.
At about $25,000, the costs of a traditional hip and a resurfacing procedure are comparable. Medicare and private insurers will pay for either, leaving it up to patients and doctors to decide.
Women represent only one-third of resurfacing patients because men are far more likely than women to need a hip replacement during middle age, when men are more prone to developing osteoarthritis.
Along with the resurfacing system made by Smith & Nephew, the F.D.A. has also approved a competing product marketed by Stryker. Both of those, as well as resurfacing devices produced by other manufacturers, have long been used abroad.
In a recent interview, Dr. Peter Heeckt, the chief medical officer of Smith & Nephew’s orthopedic division, said the company had advised that resurfacing should not be used in older women or in those with poor bone quality. A company spokesman also said recently that Smith & Nephew believed that the size of a patient’s femur was a better indicator than gender of whether resurfacing would benefit a patient, with the best results seen in patients with bigger femurs.
Experts say that hip resurfacing is more difficult to perform than a traditional implant, in part because reshaping the top of the femur is an exacting process. Some doctors express concern that American surgeons, eager to cash in on patient demand, are performing hip resurfacings after only scant training in the technique from the device makers.
The Rush study found that most complications occurred with surgeons trained by Smith & Nephew during the first procedures they performed. Dr. Della Valle said he found that data reassuring because it indicated that physicians learned quickly how to perform the procedure successfully.
When a resurfacing fails, it is then necessary to have a full hip replacement — the very procedure that the resurfacing surgery is supposed to defer for a decade or more. That is what happened with Kathy Bird, 53, a part-time academic adviser who lives near Denver.
In a recent interview, Ms. Bird said that after a doctor told her in 2006 that she needed a hip replacement, she started researching the topic on the Internet. She said she was attracted by the prospect of using hip resurfacing to postpone the need for a traditional full implant.
But her recovery from hip resurfacing was complicated, and about five months afterward, she said, she felt “a lightning bolt of pain” shoot from her hip to her knee. It turned out that the neck of her femur had fractured.
Ms. Bird said that in speaking with different doctors, both before and after her first surgery, she got differing opinions about her suitability for resurfacing.
“Some doctors have different ideas about who is an ideal candidate,” Ms. Bird said.
Even surgeons who specialize in resurfacing acknowledge that there are no conclusive tests to determine which women are the best candidates. For example, while some doctors run a bone density test on a patient, there is no agreement among surgeons about what test scores should serve as a threshold.
Dr. Edwin P. Su, who practices at the Hospital for Special Surgery and specializes in resurfacing, said, “There is a very narrow window for women to have a resurfacing.” He described ideal candidates as women in their 40s and 50s, although he added he would perform the procedure on somewhat older women if their physical conditions warranted it.
The F.D.A., in approving the Smith & Nephew and Stryker resurfacing systems, is requiring the companies to perform studies of patient outcomes. Both Smith & Nephew and Stryker recently declined to discuss interim results from the studies.
Dr. Della Valle at Rush said that the data he collected was separate from Smith & Nephew’s F.D.A.-mandated study.
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