Published 10/1/2010
Terry Stanton

Basing practice on evidence

Work group chair discusses vertebroplasty recommendation

The newest clinical practice guideline—on the Treatment of Osteoporotic Spinal Compression Fractures—includes a strong recommendation against the use of vertebroplasty. Although the AAOS Board of Directors knew that physicians who favor the procedure might object, its vote to adopt the guideline signaled an unwavering endorsement of the use of evidence-based medicine to evaluate treatment modalities.

The new guideline (see cover story, “Treating spinal compression fractures”) concludes that no compelling evidence demonstrates a benefit for vertebroplasty in patients who have radiologic evidence of a fracture with correlating clinical signs and symptoms and who are neurologically intact.

The number of vertebroplasties— the percutaneous injection of polymethylmethacrylate (PMMA) into the affected vertebral body— has increased significantly throughout the past decade. Among the Medicare population, for example, the rate of vertebroplasties increased from 45.0 to 86.8 per 100,000 enrollees from 2001 through 2005.

The recommendation against the procedure is largely based on two Level I studies (randomized, controlled clinical trials) that were published in the New England Journal of Medicine in August 2009. The studies, which compared vertebroplasty and a sham procedure, “report no statistically significant difference between the two procedures in pain measured using the Visual Analog Scale (VAS) and function using the Roland Morris Disability scale (up to 1 month and 6 months, respectively),” the Academy work group wrote in its report. Three Level II studies were also cited.

A formal Strong recommendation against the use of a procedure is rare in AAOS clinical practice guidelines (Table 1). According to the chair of the guideline work group, Stephen I. Esses, MD, the group came to its emphatic conclusion after methodically reviewing the literature.

“We went into this without any preconceived notions or preferences, and we all agreed that the practice of medicine has to be based on science and not anecdotal information,” Dr. Esses said.

“When you look at the science, strong Level I evidence suggests that vertebroplasty does not provide the types of benefits that it was previously thought to provide. And no procedure is without complication. Based upon what is known scientifically and what has been demonstrated in randomized prospective trials, vertebroplasty does not offer any advantage over a placebo control.”

Anticipating criticism
The work group did examine several criticisms that had been directed at the crucial two studies. It rejected the claim that one of the trials was underpowered, providing supporting evidence in the published guideline. “This study did have sufficient power to detect the minimal clinically important difference in pain,” the guideline states. “Although crossover patients after 1 month may have influenced the results in one of these studies, there was no crossover in the other study, which also found no statistically significant or clinically important differences.”

Dr. Esses also countered the following criticisms directed at the studies:

  • Patients selected did not have as much pain as patients in other studies. According to Dr. Esses, all patients entered in both studies had a VAS score of 7 or greater, comparable to other studies.
  • The age of fracture in the studied patients affected the findings. Dr. Esses pointed out that the age of fracture was no different than in non–Level I studies.
  • Certain fracture morphologies respond better to vertebroplasty than others. “There is no scientific basis for that,” Dr. Esses said.
  • Patients in the studies came from a large population base and therefore might not represent the patients in an individual practice. “That’s a fallacious argument because it doesn’t affect what the ultimate outcome is in a comparative, controlled, randomized series,” Dr. Esses said.

Dr. Esses acknowledged that the recommendations will generate some controversy. He noted that in some parts of the country—such as Texas, where he practices—few surgeons are performing vertebroplasty, and he said that he believes that those who do offer the procedure will discontinue it.

“I think that most orthopaedic surgeons believe that their practice should be based on the best level of evidence available,” he said. “To many, these recommendations will be somewhat surprising. But we hope that physicians will look at the basis for recommendations and adjust their practices accordingly.”

He said that interventional radiologists might have a stronger negative reaction to the guidelines than orthopaedic surgeons.

What it means to patients
To the possibility that a declaration that a procedure that had been used in a substantial number of patients is of no benefit might draw a stir from a cynical media and among consumers, Dr. Esses said the issuance of this guideline shines a positive light on physicians.

“This is an example of orthopaedists’ putting aside personal profit and commercial and financial interests and basing our recommendations only on science,” he said. “Drug companies and medical device companies are advertising to patients, many of whom don’t have the scientific background to objectively judge the truth of what they are being told. As physicians and as an organization, our job is to support and protect patients from misinformation. The AAOS as an organization must make clear—to both physicians and the public—that anecdotal information isn’t scientific information.

“If patients ask, ‘Why did I have this operation if it didn’t do any good?’ we can answer that our knowledge changes over time,” he continued. “At the time they received the procedure, it was perceived as beneficial. Our knowledge has changed.”

No special recommendations apply for surgeons whose patients have undergone vertebroplasty, Dr. Esses said. “Fortunately, if complications occur, they do so either at the time of or very shortly after the procedure. There’s not a worry that something is going to happen to these patients a year out or two years out,” he said. “We do know that patients with compression fractures are at risk for more fractures. If vertebroplasty patients present with new fractures, we have a better understanding of what should or should not be done to treat them.”

Mounting evidence
Dr. Esses said he does not expect the evidence against vertebroplasty to be contradicted by future studies. Nonetheless, he noted, “science evolves, and what we knew 2 years ago is different from what we know now and will be different again in 2 years. We have a responsibility to constantly review the literature and make recommendations based on science.”

The Level I studies of vertebroplasty rebut the oft-made contention that orthopaedic procedures are intrinsically resistant to high-level studies. “This is exactly an example of good trials being carried out,” said Dr. Esses. “The argument that ‘oh, we can’t always carry out these trials’ is not always based on hard information. These are both excellent trials, carried out in two separate countries, coming to the same conclusion. It’s not logistically impossible to carry out good science.”

Disclosure information: Dr. Esses reported affiliations with Orthopedics, Spine, and The Spine Journal.

Terry Stanton is senior science writer for AAOS Now. He can be reached at tstanton@aaos.org