Commentary

Vertebroplasty, cognitive dissonance, and evidence-based medicine: What do we do when the ‘evidence’ says we are wrong?

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Cognitive dissonance describes how we respond to conflicting information that challenges our existing belief, the uncomfortable feeling we get when new evidence calls into question things that we “know” are true.

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To the point: two recent clinical trials 1,2 have called into question the efficacy of vertebroplasty for treating osteoporotic vertebral compression fractures and have led many of us to question many of our assumptions, not only about vertebroplasty but also about evidencebased medicine.

Osteoporotic vertebral compression fractures are very common: more than 700,000 are estimated to occur in the United States annually. 3 They are costly and are associated with a risk of death. 4 Fortunately, most heal without problems over 4 to 6 weeks with conventional treatment, ie, activity modification, analgesics, and bracing.

However, some patients do not seem to do so well and are debilitated by the pain of the fracture. Conventional fracture surgery carries very high risk and poor outcomes, 5 and so has been reserved mostly for patients with neurologic deficits.

VERTEBROPLASTY GOES MAINSTREAM

Given these facts, investigators began looking for alternative treatments. One that rose to the fore was polymethylmethacrylate cement to stabilize the fracture. This technique, called vertebroplasty, involves injecting liquid cement through a needle into the vertebral body, where it hardens and is thought to restore stability.

Since the first description of vertebroplasty for treating symptomatic hemangiomas, 6 many papers have been published about the procedure and about similar ones, now grouped under the general heading of vertebral augmentation . This includes kyphoplasty and other newer proprietary techniques. These procedures have been widely accepted, and their use is growing. They have shown good results in several prospective case series, and nonrandomized and randomized controlled studies have shown them to be more effective than conventional medical treatment. 7–25 For example, VERTOS, a small prospective randomized trial, showed that vertebroplasty was superior to conventional medical treatment. 25 When Wardlaw et al 24 showed that shortterm outcomes were better with kyphoplasty than with conventional medical therapy in a prospective randomized trial, many of us had moved past questioning whether vertebral augmentation is effective and were debating the relative merits of different methods and materials.

On a personal level, most of us became proponents of these procedures because we saw dramatic results—usually unequivocal. Most patients report significant improvement in pain immediately after the procedure, and many bedridden patients are able to leave the hospital within hours. In spine surgery, few procedures give such dramatic results with so few complications.

TWO NEW STUDIES UPSET ESTABLISHED BELIEF

This is why I am having such a hard time digesting the results of the trials by Buchbinder et al 2 and Kallmes et al, 1 published in the August 9, 2009, issue of the New England Journal of Medicine . Both were randomized controlled trials that used sham surgery rather than conventional medical treatment as the control. The sham procedure in each trial was the same as the intervention, with local anesthetic infiltration of the periosteum and mixing of the cement (so that the patients smelled its distinctive odor), but without placing the needle into the vertebra and injecting the cement.

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Treating the renal patient who has a fracture: Opinion vs evidence

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