Back surgeons savor cutting edge
New spinal fusion debuts in Pleasanton
By Matt Carter – STAFF WRITER
PLEASANTON — TWO SURGEONS will perform back surgery at ValleyCare Health Center on Tuesday using a genetically engineered protein to stimulate bone growth — just two weeks after the Food and Drug Administration approved the new spinal fusion technique.
Over the years, surgeons Joe Grant and Kevin Booth have fused hundreds of vertebrae to relieve patients’ chronic lower back pain. The procedure is sometimes performed when a patient has a disc — the shock-absorbing cushion between vertebrae — that has failed and is pressing on nerves.
In the past, the operation required that surgeons take small chips of bone from each patient’s hip, placing the chips inside artificial “cages” that are implanted between the vertebrae. The chips stimulate the growth of new bone that grows through the cages, fusing the vertebrae together.
But removing the bone chips can cause more pain than the back surgery itself, and also can lead to a longer recovery.
During two operations Tuesday, Grant and Booth won’t be placing bone chips inside the cages. Instead, they’ll insert a small collagen sponge
saturated with a protein known in scientific circles as recombinant human bone morphogenetic protein, or rhBMP-2.
That’s quite a mouthful, so the new technique for spinal fusion is being marketed as the InFUSE bone graft method by Tennessee-based distributor Medtronic Sofamor Danek. The protein, previously approved for use only on hard-to-heal fractures of long limb bones, was developed and is manufactured by Wyeth-Ayerst Laboratories.
When used in spinal fusion surgery, the protein plays the same role as a hip bone chip, encouraging the growth of bone-producing cells inside cages.
The cages, which can be made of titanium or machined from bone taken out of cadavers, have threads on the outside like a screw. That’s exactly how they’re inserted: surgeons insert an expander to re-create the space formerly occupied by the disc, make grooves in the vertebrae, and screw the cages in.
“It’s like tool and die work,” Grant joked while demonstrating the procedure with a plastic model of a spine.
Although there are 84 surgeons in California trained to perform the InFUSE procedure, only 13, including Grant and Booth, are also qualified to use a “minimally invasive” laparoscopic technique that employs a camera inserted through a small incision.
“We’ve been doing laparoscopic spine fusions for about seven years,” Grant said. “A lot of people have moved away from it, because it’s technically difficult and time consuming. We’ve gotten the time down to under two hours — about 20 to 30 minutes to actually see the spine, and another 40 to 50 minutes to fuse it.”
It’s a capability ValleyCare officials want to publicize. In ValleyCare Medical Center’s two-year-old laparoscopic suite, surgeons not only perform back surgery but also remove cancerous prostates, repair hernias and perform a weight-loss procedure where an adjustable band is placed around the stomach.
“We’ve been having great success” with laparoscopy, said spokeswoman Kathy Campbell. “Part of it is just equipping the O.R. — it cost millions and millions of dollars.”
With the latest equipment and teleconferencing capabilities, Grant says it’s one of the most advanced operating rooms in the country.
The payoff in laparoscopy accrues to the patient: less pain and shorter recovery time, because less tissue and muscle fiber gets sliced.
Grant, 48, and Booth, 36, are partners in the Northern California Spine Institute, which is affiliated with ValleyCare Medical Center in Pleasanton and San Ramon Regional Medical Center. The third partner in the venture is Dr. James Fontaine, who specializes in rehabilitation and pain management.
Grant and Booth spend most of their time at ValleyCare, working one day a week in San Ramon and one day a month at an office in Sonora, Grant said.
Grant thinks enough of the InFUSE bone graft method that he advised some patients who were candidates for spinal fusion to wait for the FDA to approve the new technique.
The FDA gave doctors the go-ahead July 2, after a study involving 279 patients showed that the InFuse technique was as good or better than bone chips in fusing vertebrae.
In the study, 143 patients were treated with the protein, while 136 patients in a control group got the traditional bone-chip-in-cage. Two years after surgery, fusion was successful in 94.5 percent of the patients treated using the InFUSE technique, compared to 88.7 percent of patients in the control group. The overall success of the surgery, including how effective the surgery was at reducing back pain, was 57 percent in both groups.
Grant estimated that he and Booth perform about 300 spinal fusion procedures each year. When possible, they prefer to use cages made from bone taken from cadavers, not titanium.
One reason for this is that a titanium cage makes it harder to read X-rays when determining whether vertebrae have properly fused. There’s a similar problem with MRI (magnetic resonance imaging) machines, where a titanium cage will produce an “artifact” that interferes with interpreting images.
Although the FDA has only approved the InFUSE method with the use of titanium cages, Grant said he and Booth will give patients who prefer bone cages the option to have an “off label” procedure performed.
“In terms of results, we haven’t seen a difference,” he said.
With 190,000 spinal fusions performed in the U.S. each year, InFUSE seems to have a bright future. The FDA has ordered three ongoing studies to assess whether the protein can cause cancer or whether it affects antibody response during pregnancy.
A small percentage of patients in the clinical trials of InFUSE — less than 1 percent — developed antibodies to the protein rhBMP-2. A similar number of patients who received hip chip bone grafts also developed the antibodies.
The antibodies can lower rhBMP-2 levels, and studies in mice suggest that low levels of the protein may cause birth defects or kill a pregnant woman’s fetus.