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New Memory Coiling Spiral Replaces Center of Disc

What can hold two structures apart, support hundreds of pounds of weight, and withstand millions of cycles of compression? Your intervertebral disc! Problems happen when the disc is removed due to injury or disease. Scientists have tried finding solutions. They've tried filling the space with bone chips, inserting mesh cages filled with bone chips, and attaching plates and screws to hold it all together.

Now there's a memory coiling spiral to act as a nucleus pulposus implant. The nucleus pulposus is the center of the disc. It sits inside an outer shell called the annulus. Dr. J. L. Husson from France has been working on the design since 1990. The implant can be put in right after the nucleus pulposus is taken out. The annulus (the outer layer) remains in place. The coil is in the shape of a spiral. It fills the disc cavity without being tied down or glued in. A special manufacturing process allows it to hold its coiled shape
once in place.

The best placement for the coil is right in the center of the disc space. But it's okay if it moves or twists inside the disc. The doctor puts the spiral right inside the disc to allow for a perfect fit. When the spiral fills the nucleus space, the annulus takes up its old functions. The risk of a new herniation is gone.

Researchers have tested this new implant using human cadavers. Up to 50 million cycles of force were applied in all directions. No wear and tear was seen. The next step was to test it in live patients. Results from the first five patients are the subject of this report.

After two years the implant hadn't shifted or moved. Everyone had less pain and better function. Everyone was satisfied with the results, and four of the five patients went back to work. X-rays show that the implant is keeping the proper disc height.

The authors think this new implant will be a good way to treat disc problems without spinal fusion. Soon it will be possible to insert the implant with a tiny incision, making it an even less invasive operation.

References: J. L. Husson, et al. A Memory Coiling Spiral as Nucleus Pulposus Prosthesis. In Journal of Spinal Disorders & Techniques. August 2003. Vol. 16. No. 4. Pp. 405-411.

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