New Technology for Spinal Stenosis
Low back pain from disc degeneration, spinal stenosis, or spondylolisthesis may benefit from new technology. Interspinous process spacers are devices that can be implanted between the spinous processes. to limit spinal motion.
A spinous process is the part of the vertebral bone that protrudes away from the vertebral body. You can feel the tips of the spinous processes as bumps along the back of your spine.
Putting a spacing device between two spinous processes holds the spinal segment in slight flexion. It limits motion in extension without preventing rotation or side bending.
The effect is to stabilize the spine without rigid fusion. By holding the spine in this position, there is less pressure put on the spinal nerves. The facet (spinal) joint cannot slide as far back, thus keeping the space open around the spinal nerves.
Interspinous process spacers aren't new. They have been around since the 1950s. But the design and technique for implanting them are much improved these days. Currently, only the X STOP spacer is approved by the FDA for patients with spinal stenosis. Two other systems (Wallis Normalization and DIAM) are under being studied.
New implant designs include ways to prevent the device from getting dislodged. They come in many sizes to give the surgeon choices as to how much spinal flexion is allowed while preventing extension. Some are made of titanium while others are polyethylene coated with silicone.
Only very limited results are available after one- to two-year studies with the X STOP. No data has been published on the other implants. There are concerns about the implant causing pain. No one is sure what will happen with their long-term use.
The authors of this update review say that results so far are very promising. For best results, patients must be selected carefully. More study will help tell which device is best for each type of problem. For now, this new technology remains investigational.
References: David H. Kim, MD, and Todd J. Albert, MD. Interspinous Process Spacers. In Journal of the American Academy of Orthopaedic Surgeons. April 2007. Vol. 15. No. 4. Pp. 200-207.
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