Trial will explore plastic vertebrae

Researchers said Friday they are ready to launch a late-stage trial of vertebroplasty, a procedure in which a prosthetic vertebra is created by injecting plastic cement into the interior of a vertebra fractured by osteoporosis. The Mayo Clinic scientists conducting the Phase 3 study say the new technology improves function and relieves pain. “Vertebroplasty is a very safe and easy procedure that seems to work quite well,” David Kallmes, a Mayo Clinic interventional neuroradiologist who is doing the study, told United Press International. “The problem is that it has never been studied formally so we don’t know as much as we could about it. For instance, our retrospective study, which simply looked at past records, showed us that vertebroplasty also makes it easier for people to move, tie their shoes, mow their lawn, and live life fully. Before it was primarily thought of as a way to relieve pain,” he said.

Kallmes and his colleagues at the Mayo Clinic reviewed the records of 113 patients with spinal compression fractures treated with vertebroplasty at his institution. Almost all of them filled out the Roland-Morris Disability Questionnaire, which measures back pain and function, before the procedure, and a smaller number completed it afterwards at intervals up to one year. Prior to treatment, the average RDQ score was 18 on a scale of 23. That score dropped to 11 immediately after treatment and remained an 11 throughout the remainder of the study.

Kallmes said that the procedure was first developed for cancer patients about 10 years ago and is still widely used in Europe for cancer that has spread to the spine. He added that the Mayo Clinic uses it routinely for patients with multiple myeloma, but he and his colleagues found that the results were not as good for other types of cancer and nowhere near as good as the results they obtained for people with osteoporosis. According to Kallmes, vertebroplasty is performed on an outpatient basis and takes about 45 minutes. The patient lies flat for an hour or two afterwards to let the plastic cement harden fully, then is discharged. “The critical factor in this procedure is being able to see where the cement is going; that’s why it’s done in the radiology suite,” Kallmes explained. “If you are not well-trained and don’t have extremely good radiological equipment, the cement could get outside the vertebra and cause a blockage in the lungs or nerve injury and paralysis in the spinal cord. Usually our complication rate is 1 percent, and that’s from the rib fractures our multiple myeloma patients sustain from lying on the table for so long.”

Vance Watson, director of interventional radiology at Georgetown University Medical Center, told UPI that he uses vertebroplasty often and would welcome a clinical trial to explore the procedure’s boundaries. “It’s one of the few treatments we do where we improve people’s lives very quickly,” said Watson. “It’s very gratifying.” Watson remarked that his experience echoed the results of the Mayo study, with some patients reporting significant pain relief and others not much, but many saying they could function better as a result of the procedure. “A clinical trial would be a great help in these circumstances,” Watson remarked. “Retrospective data is enticing but is sometimes wrong. A prospective trial will prove how well the procedure works in a variety of patients, and give us data about its results we don’t currently have. This could lead to wider acceptance of vertebroplasty within the medical community, which could reduce the number of people with spinal compression fractures who must live with decreasing function and pain,” he said. Kallmes said that the trial, called INVEST (investigational vertebroplasty efficacy and safety), was underway around the world and involves about 300 people.

Science Daily
January 17, 2006

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