A new bone graft, INFUSE®, by Medtronic, uses recombinant human bone morphogenetic protein-2 (rhBMP-2) to stimulate bone growth, eliminating the need to harvest patient bone and improving the success of spinal fusion surgery.
Local orthopedic surgeon Matthew Berchuck, MD, has been using INFUSE since it was FDA-approved two years ago. "Fusion operations have been around for over 100 years," he explains, "and the gold standard for doing a fusion is taking some bone graft from the pelvis during the spine operation and laying that on the fusion bed. One of the problems with taking bone graft from the pelvis is that between a quarter and a third of patients will have some long-term pain at the site where the bone graft was taken. Also the success of a fusion is not 100 percent."
Bone grafts aren't needed with INFUSE, however, eliminating the pain and complications relating to bone harvest. In addition, the new procedure offers a higher fusion rate than in autograft control patients.
"What this BMP-2 does is stimulate … undifferentiated cells in your body to differentiate along the lines of bone-forming cells. It's the formation of bone in the area of the fusion which stimulates the fusion process, so it simplifies the operation," says Berchuck.
The INFUSE Web site explains how the procedure works: To use INFUSE® Bone Graft, surgeons mix the rhBMP-2 powder with sterile water and then apply it to collagen sponges. The sponges are inserted inside a pair of metallic cages, which are then implanted between the vertebrae. The thimble-like cages stabilize the spine while fusion occurs and maintain the proper height between the vertebrae.
The FDA has approved INFUSE for anterior lumbar fusion and for open fractures of the tibia. "BMP is also being used by orthopedic surgeons who treat fractures," Berchuck explains. "Specifically, there have been some studies involving tibia fractures where they've been able to stimulate healing of fractures that have been slow to heal. Open fractures tend to be particularly difficult to heal, and folks have been using that as an adjunct to the treatment of open tibia fractures."
The new technology is also used by many in off-label ways as well. "In my experience, it works best when used in the manner that the FDA has specifically approved it for. But others, in an effort to expand the usage of it, are using it in other types of fusions," says Berchuck. "People have tried using it from a posterior approach to the low back, and some people have even used it in the neck and on longer scoliosis-type fusions too. It's an evolving body of knowledge. But people are very optimistic about it."
Despite its promise, Berchuck guesses that INFUSE is used for fewer than 30 percent of lumbar fusion surgeries performed today.
"One of the factors that needs to be considered in BMP, like a lot of new technology, is that it is very expensive," he says. "Of course you've got to weigh the costs of any new technology versus; (1) the perceived benefits; and (2) the cost in and of itself. If Medicare is only going to pay a certain amount to the hospital for the whole hospitalization, and if the BMP costs more than that, the hospital can't lose money on its cases or they're going to go out of business. That's been one of the issues."
