Surgeons study artificial bone’s ability to replace weakened spinal disks

After preliminary success using artificial bone to replace degenerative spinal disks in the neck and lower back, neurosurgeons at Washington University School of Medicine and Barnes-Jewish Hospital are preparing a study to formally compare the performance of the synthetic material against that of real bone.

“The artificial bone we’re using, which is known by the brand name Vitoss, has been FDA-approved for these kinds of procedures for two years,” notes Neill Wright, M.D., assistant professor of neurological surgery and of orthopaedic surgery. “We’ve been pleased with the results, but we want to begin a formal, prospective comparison of how well it does in comparison to the material we used previously, which was bone taken from deceased donors.” For the study, researchers are seeking 154 patients with degenerative disk disease in the neck and corresponding neck or arm symptoms. Study participants must have already attempted and failed to relieve their symptoms through conventional nonsurgical treatments such as physical therapy. Historically, when spinal disk degeneration led to untreatable pain, physicians would remove the failed disk and fuse that level of the spine by replacing the failed disk with bone taken from another region of the patient’s skeleton, most commonly from the hip. “Because it was the patient’s own bone, it would fuse very well with the rest of the spinal structure,” Wright says. “But this had the downside of forcing a second surgical procedure to take out the bone that we used for the fusion, and that second procedure brought added risk of infection, bleeding and pain.” Approximately a decade ago, surgeons began to rely on a different source for material to treat most patients with failed vertebrae: bone taken from donors who had died. This material doesn’t fuse as well as the patient’s own bone and is sometimes difficult to obtain, but it reduced the need for multiple-site surgeries. Thorough sterilization of any donated bone was also necessary. “To my knowledge, there hasn’t been a single case of someone getting an infectious disease from a bone graft, but you’re still taking bone from another person, so there is always the theoretical risk of getting an infection,” Wright explains. Vitoss, the material used for fusions by Washington University orthopaedic and neurological surgeons at Barnes-Jewish Hospital, has the same porosity and sponge-like structure as human bone tissue. The fusion procedure typically requires the insertion of screws into nearby bone. Surgeons can use the holes for the screws to take marrow from nearby bone and inject it into and around the artificial bone. “Retrospectively, the patients who’ve received this procedure have seemed to be holding up quite well,” says Wright. “Now, though, it’s time to take a hard scientific look at how well the results delivered by artificial bone compare to fusions using cadaveric bone.” (Source: Washington University School of Medicine: June 2006.)