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During the past decade, vertebroplasty and kyphoplasty have rapidly gained acceptance as routine treatments for patients with painful vertebral fractures. Both procedures involve percutaneous injection of polymethylmethacrylate (PMMA) “cement” into the affected vertebral body. Uncontrolled studies and anecdotal observations have suggested that these procedures reduce pain dramatically in some patients. But placebo-controlled randomized trials were lacking until 2009, when two such studies were published (JW Gen Med Aug 5 2009).
The two trials — conducted in the U.S., the U.K., and Australia — included a total of 209 patients whose average duration of pain at enrollment was several months. Patients were randomized to receive either vertebroplasty or sham procedures; local anesthetic was injected at the site of fractured vertebrae in both the vertebroplasty and sham groups, but PMMA was actually injected into the vertebral body only in the vertebroplasty group. The researchers assessed outcomes at various intervals between 3 days and 6 months. Results were similar in the two trials: Pain and disability scores improved from baseline in both the vertebroplasty and sham groups, with no significant differences between groups.
Predictably, advocates of vertebroplasty have criticized these studies, citing inadequate volume of injected cement, small study size (many eligible patients declined to participate), and failure to enroll patients early enough after fractures occurred. The study authors have responded and defended their findings (N Engl J Med 2009; 361:2097 and elsewhere). In part, the criticism that vertebroplasty was performed too late is addressed by another randomized (but not sham-controlled) trial in which 50 patients were assigned to vertebroplasty or conservative treatment an average of 1 week after fractures occurred (Spine [Phila Pa 1976] 2009; 34:1349); at 3 months, outcomes were similar in the two groups.
Many people are surprised by these findings, but we know that pain subsides naturally within a few weeks in many patients with vertebral fractures and that placebo effects of invasive procedures can be considerable. If subgroups that clearly benefit from vertebroplasty exist, they haven't been identified yet. In ongoing trials, researchers are examining whether kyphoplasty (inflation of a balloon before injection of PMMA) is better than vertebroplasty. In the meantime, the 2009 trials should dampen our enthusiasm for these procedures.