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New Bone Cement Could Improve Spinal Treatments for Osteoporosis Sufferers

Vertebroplasty, a procedure to shore up fractured bones, has at times been dismissed as unnecessary, but a new bonding material could change this
osteoporosis, vertebroplasty, pain



© ISTOCKPHOTO.COM/MADS ABILDGAARD

When the pain gets to be too much for those suffering from spinal bone fractures due to osteoporosis, there are generally two options: bed rest (often combined with a protective brace and painkillers) or a controversial procedure known as a vertebroplasty, which involves injections of bone cement.

In a vertebroplasty, a surgeon uses a hollow-point needle to inject a cementlike substance, typically poly(methyl methacrylate), or PMMA, into any cracks or fractures found in the spine. (Although osteoporosis weakens bones throughout the body, vertebroplasty is used exclusively to treat spinal problems.) The surgeon will also use a fluoroscope, which includes an X-ray device and a fluorescent screen, to monitor the needle's location inside the body and ensure that the sealant is injected into the proper location.

Both approaches to curbing the pain associated with vertebral compression fractures—a condition that affects about 1.4 million people worldwide, with more than half of those cases in the U.S.—have their detractors and supporters.

Proponents of bed rest note that most patients' fractures heal without the need for any type of medical procedure, although this could take several weeks. Bed-rest advocates see vertebroplasty as a treatment that is unnecessary at best and could actually leave the treated bone around the cement in a weakened condition. Two studies published earlier this month in The New England Journal of Medicine (NEJM ) appear to support these views, finding that participants in a study who received vertebroplasty felt no less pain than participants who were given a placebo treatment, in which no bone cement was injected into the spine.

In one of the studies, 131 patients suffering from osteoporotic vertebral compression fractures underwent either a vertebroplasty or a simulated procedure where the bone cement was not actually used. Much to the surprise of the researchers, both sets of patients showed immediate improvement after the procedure, says David Kallmes, a professor of radiology in the Mayo Clinic's radiology department who participated in the research. "My sense is that (vertebroplasty) is overused now," he says, adding that he does perform the procedure. One concern, which he expressed after a 2006 Mayo Clinic study of vertebroplasty, is that vertebrae adjacent to fractures treated with bone cement tend to fracture significantly sooner than vertebrae farther away.

Others are concerned with the use of PMMA, a clear plastic that's also an ingredient in Plexiglas (commonly used as a shatterproof replacement for glass) and Lucite, which is used to make the surfaces of hot tubs, sinks and one-piece bathtub–shower units, among other things. Although vertebroplasty complications are extremely rare, there is a danger of the cement leaking outside of the spinal area and potentially causing infection, bleeding, numbness and other problems.

Despite these concerns, other doctors have seen vertebroplasty's benefits time and again. The NEJM studies provide "good food for thought that will help us do more strategic analysis of when to do a vertebroplasty," says Clark Bernard, a neurosurgeon at King's Daughters Medical Center in Ashland, Ky. But his experience performing the procedure over the past decade has shown that it is effective in providing faster relief than bed rest and painkillers to patients in pain, particularly those suffering from cancers that metastasize and invade the spine from other parts of the body. Vertebroplasty is effective at "expediting pain relief," he adds.

A new substance that received U.S. Food and Drug Administration approval in June to be used in vertebroplasties could greatly alter the discussion: The Cortoss bone augmentation composite developed by Malvern, Pa.–based Orthovita, Inc., over the past 14 years is a pearly white paste that the company says has the ability to strengthen bones by helping them build up calcium phosphate.

Although the publication of the NEJM articles has coincided with a dip in Orthovita's stock price, Theodore Clineff, the company's vice president of research and product development, points out that the studies tested PMMA, not Cortoss.

Bernard has used Cortoss to perform vertebroplasties on six patients since early July and says he thinks it is safer than PMMA, which can be toxic if too much is used.

Cortoss is also generally more expensive than PMMA. Whereas a typical vertebroplasty can cost between $2,000 and $5,000 , those performed using Cortoss tend to be at the higher end of that scale. Clark notes that Cortoss costs several times more than PMMA. Orthovita acknowledges that Cortoss does generally cost more than PMMA per unit but adds that Cortoss reduces the risk of subsequent re-fracture compared with PMMA, which means osteoporosis sufferers would need fewer treatments over time.

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