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FDA issues warning about bone cement

By KATRINA WOZNICKI, UPI Science News

WASHINGTON, Nov. 5 (UPI) -- The Food and Drug Administration has issued a warning about a type of bone cement used to treat fractures in the spine that has been linked to numerous serious side effects, but orthopedic surgeons suggest the alert might be over-reaching.

The bone cement, called polymethylmethacrylate, has been used for nearly 40 years in surgery. Monday's warning from the FDA said two procedures -- vertebroplasty and kyphoplasty -- used to treat spine fractures, have been associated with complications such as tissue damage and nerve root pain due to cement leaking into the body. The agency said it also has received reports of pulmonary embolism -- or blood clots in the lungs -- respiratory and cardiac failure and even death, though no figures were made available.

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"FDA is currently working with appropriate professional organizations and manufacturers of orthopedic devices to consider the regulatory options available to evaluate the long-term safety and effectiveness of bone cement in vertebroplasty and kyphoplasty procedures," the agency said in its statement. "We encourage you to be aware of considerations and recommendations regarding patient selection, vertebroplasty and kyphoplasty techniques, complications, and patient monitoring described in the literature when considering these procedures to treat osteoporotic compression fractures of the spine."

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The FDA's statement included a request that physicians report any side effects seen from these two surgical spine treatments.

The agency did not return calls for comment.

Dr. Thomas A. Einhorn, chairman of orthopedic surgery at Boston University Medical Center in Boston, Mass., and a spokesman for the National Osteoporosis Foundation, said vertebroplasty and kyphoplasty are performed daily around the world and serious complications are rare.

"I think it's pretty clear that polymethylmethacrylate bone cement is safe," Einhorn told United Press International. "The reason I say that (is) it's exactly the same material that's used thousands of times of year in the replacement of joints."

Einhorn also said there is no conclusive evidence this type of bone cement directly causes tissue and nerve damage. "While it seems that would be a very dangerous thing to happen, there's no evidence specifically from the appearance of bone cement where you would not want it and patient symptoms," he said. "Patients do not generally experience symptoms from leakage of bone cement."

He added, "anything that we do medically carries with it a certain risk. I think the FDA is taking the position in inducing a very high level of caution. I think it's appropriate for a body like FDA if they have to choose between overly cautions and under cautious that they be overly cautious. That's their job."

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Dr. Steven Garfin, chairman of orthopedic surgery at the University of California at San Diego, whose 2001 report in the journal Spine is cited in the FDA statement as a reference, said he does not understand the FDA's alarming tone.

"The clinical outcome of these two procedures have been wonderful," Garfin told UPI. "It's been a 90 to 95 percent success rate. They've proven true internationally. The FDA has been concerned, and I'm not sure why."

Garfin added, "Why the FDA is saying you can't do it in the spine, but you can do it elsewhere ... has been unclear to me from the start."

Vertebroplasty involves injecting a needle into the bone and under high pressure, pushing the cement into the bone. Kyphoplasty involves a larger needle that also is injected into the bone, but the cement is pushed through with lower pressure. The latter procedure is similar to a technique used to open arteries called angioplasty, except a balloon creates an open space in the bone for the cement.

Needle placement could be key. "It's not the cement," Garfin said, "it's the direction the needles were placed." Garfin, who has studied effects from kyphoplasty, said he knows of no reports of death from this procedure. However, he acknowledged vertebroplasty's side effects -- such as cement getting into the lungs -- might be underreported.

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The side effects listed by the FDA, Garfin added, are risks associated with any operation.

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