Studies Raise Doubts About the Benefits of Vertebroplasty
Evidence reveals bone cement injection has no benefit over placebo procedure for spinal compression fractures.
Two studies concluded in 2009 that a common repair for spinal compression fractures in people who have osteoporosis offers no more benefit than a sham injection and may carry serious risks, experts said Wednesday.
The studies, which were published in The New England Journal of Medicine, were the first clinical trials to test a popular and expensive procedure called vertebroplasty against a placebo, and many experts said they were stunned by the results, which showed that patients got equal amounts of modest pain relief whether they got vertebroplasty, where bone cement is pumped into broken vertebrae, or a dummy injection.
David F. Kallmes, MD, an interventional radiologist at the Mayo Clinic in Rochester, Minn., who led one of the studies, said he thought something was wrong with the data when he finally learned the results.
“I just really couldn’t believe it when they told me,” Dr. Kallmes said in an interview. (In double-blinded clinical trials, neither researchers nor patients are allowed to know who is getting the investigational treatment or the placebo.)
Dr. Kallmes said he was relieved to learn that a team of Australian researchers had gotten roughly the same results in a similar study.
“I think both trials show that vertebroplasty is no better than a sham procedure for either improving pain, function or quality of life,” said Rachelle Buchbinder, PhD, a rheumatologist and director of the Department of Clinical Epidemiology at Cabrini Hospital in Malverne, Australia.
“I don’t think there’s any benefit of having a vertebroplasty and there are potential risks, and they haven’t really been fully elucidated to date,” Dr. Buchbinder added.
In her study, which enrolled 78 patients with spine fractures, one participant who received the cement developed a serious bone infection called osteomyelitis.
And previous research has suggested that bone cement may increase the risk for fractures in adjacent vertebrae because it changes the way the spine is able to absorb shock.
Still, other experts said that while they found the studies to be rigorous and well designed, the results were tough to reconcile with personal experience.
“I have seen patients come into the O.R. in so much pain that they could not walk,” says Scott Boden, MD, director of the Emory Spine Center in Atlanta, who was not involved in either study. “They get the cement and two minutes later they are walking out the door. It’s that fast.”
Such cases have convinced many in the medical community that the procedure works, and Dr. Boden said he believes the procedure may still have benefit for certain kinds of patients, particularly in those who have recent fractures.
During the previous six years, the number of vertebroplasty procedures performed in the United States has doubled, according to Medicare data, from 4.3 to 8.9 procedures for every 1,000 persons, though questions and worries about the risks remained.
And vertebroplasty is expensive. The total cost is usually around $5,000 when the cost of an MRI scan is included.
So in 2002, Dr. Kallmes convinced the National Institute of Arthritis and Musculoskeletal and Skin Diseases, or NIAMS, part of the National Institutes of Health, to give him money to compare vertebroplasty to a placebo.
Researchers rarely test surgical procedures, even minimally-invasive ones, against a placebo because unlike drug studies, where it’s possible to hand out harmless sugar pills, placebo surgeries involve breaking the skin, a move that can be ethically dicey because it opens the door to infections and other kinds of dangerous complications.
Dr. Kallmes also didn’t want to leave patients in pain if they got the dummy injection, so he told all study participants that they could get the other intervention if they had not experienced adequate relief after 30 days.
He eventually enrolled 131 patients who were randomly assigned to receive either the bone cement or a dummy injection of short-acting painkillers.
Study investigators took great pains to make patients who got the dummy injection believe they were getting the real thing, including opening a container of the bone cement so the distinctive smell, something like nail polish remover, would waft through the air.
And each month, as he submitted his data, he said he half expected someone would call and tell him to cancel the study, something that happens when results show overwhelming benefit, or danger, early on.
But the call never came.
In the final analysis, patients in both the placebo group and the treatment group reported that on a scale from 1 to 10, their pain dropped by an average of about three points after 30 days, whether they got the bone cement or not.
The Australian study, which was very similar, had almost the same results.
“The placebo effect, I don’t think, can be underestimated,” said Dr. Buchbinder.
“Especially for an invasive procedure, people have a higher expectation that they will benefit. They put themselves on the line if they have to have an invasive procedure, so they really have to buy into it and I think that really heightens the placebo response.”
Dr. Buchbinder said that after the study, she received a visit from a grateful patient who had been flown to the hospital by air ambulance because the fracture in his back was so painful.
He was enrolled in the study, and after the procedure, his pain was so much better than he was able to drive home.
Curious, Dr. Buchbinder looked up his number to see which treatment he’d gotten.
He had gotten the placebo.
Whether his own belief was enough to blunt his pain, or whether the fracture may have healed on its own, as many do, is anyone’s guess, Dr. Buchbinder said.
“Unless you do rigorous studies, no matter how amazing it looks in these instances, I don’t think you actually can know unless you’ve done the studies,” she said.