New device could radically change back surgery

WASHINGTON (AP) -- The government on Tuesday approved sales of a device that could radically change surgery for certain back pain sufferers -- because it carries a genetically engineered drug to spur bone growth.

The Infuse bone graft device is for people with spinal disc degeneration, a major cause of low back pain. A weakened disc that bulges from between two vertebrae places painful pressure on spinal nerves.

While many people recover with time, others undergo surgery to fuse the two vertebrae surrounding the weakened disc.

First, a metal cage is placed in the spine. Then doctors do a second surgery, culling bone from the patient's hip to place inside that cage. Patients often call the hip operation more painful than the spinal surgery -- and nearly a third still have hip pain two years later, says Infuse manufacturer Medtronic Sofamor Danek.

The new Infuse device would eliminate the need for the hip operation. Infuse's metal cage contains a genetically engineered protein called rhBMP-2 that spurs the body to grow brand-new bone at the site instead of needing to use bone from the hip.

Until now, patients have only rarely received a bone implant infused with this protein -- to fix an uncommon condition where long bones of the limbs won't heal properly, said Dr. Celia Witten of the Food and Drug Administration.

A study compared 143 patients given the Infuse device with 136 who underwent standard surgery for a degenerated disc, and found that Infuse works just as well without requiring the extra surgery. The overall treatment success, including a measure of patients' post-surgery back pain, was about 57 percent in both groups, Witten said.

Medtronic said the device will be widely available within a few weeks, and will cost about $3,500 to $5,000 in addition to the cost of surgery. But the Memphis, Tennessee-based company said half of that cost is recovered by not having to undergo the hip operation.

The study didn't uncover any risks with using Infuse beyond those of traditional spinal surgery, Witten said. But it does come with some warnings:

--It's possible the protein could trigger excess bone growth, something Witten said doctors should catch on routine follow-up visits, and a risk that increases if doctors use a different surgical technique than Medtronic studied.

--It should not be implanted in women suspected to be pregnant since the protein's effects on a developing fetus are not well understood.

FDA has ordered Medtronic to do additional laboratory studies ensuring the protein doesn't spur cancer growth or cause long-term immunological effects.

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