Effect of X-stop on Motion and Space Inside the Spinal Canal
Looking for some relief from that back pain caused by spinal stenosis but don't want the roto-rooter surgery? Here's some good news: there is an alternative treatment available. As this study shows, the use of the X-stop spacer can achieve the desired relief from pain without decompression surgery.

To help you understand what this is all about, let's explain a few terms. First, spinal stenosis is a narrowing of the spinal canal. The spinal canal is the channel or opening created by the vertebral bones stacked on top of each other. Inside the canal is the spinal cord as it travels from the brain down to the lumbar spine.

Degenerative changes associated with aging such as bone spurs, thinning or bulging of the discs, collapse of the vertebral bodies, and stiffening or infolding of the spinal ligaments all reduce the space inside the canal. Since the spinal cord doesn't shrink with age, the net result of stenosis is pressure on the spinal cord and/or the spinal nerve roots.

Decompression (sometimes referred to as "roto-rooter" surgery) involves scraping away the excess bone and restoring space within the canal. Sometimes the surgeon performs a laminectomy (removes a portion of the bone from around the spinal cord). But decompression doesn't improve the disc space or realign the compressed vertebrae.

That's where the X-stop comes in. This device is implanted between the spinous processes of two vertebrae. The spinous process is the bony knob you feel along your backbone. It is a projection of bone off the back of each vertebra that provides a place for ligaments and muscles to attach.

By slipping the X-stop between the spinous processes, it's a little like using a jack to lift your car off the ground. It separates the vertebrae and puts them in a slight bit of flexion -- just enough to take pressure off the spinal cord, spinal joints, and spinal nerve roots. It's a fairly new treatment technique so research is ongoing to evaluate its effectiveness.

In this study from Scotland, orthopedic surgeons used a positional or stand-up MRI to measure the increase in space around the spinal cord. A positional MRI takes pictures of the disc height, spinal canal area, and space around the spinal nerve roots with the patient sitting, lying down, and standing up (weight-bearing). The effects of the X-stop on lumbar spine movement were also measured using positional MRIs.

The X-stop isn't used routinely with patients who have painful spinal stenosis. Usually, physicians prescribe antiinflammatories, physical therapy, and/or steroid injections first. But if these conservative forms of treatment don't help, then surgery is considered.

There were 48 patients (men and women) who met that criteria and were included in this study. Some patients (29 of the 48) received a single-level X-stop while others (19 or the 48) had double-level procedures.

Positional MRIs were taken before X-stop implantation and again two years after surgery. Patients also filled out a survey designed to assess change in pain and patient satisfaction.

Results were variable among the 39 patients still in the study after two years. There was no improvement (or only minor changes) in pain and function for one-fourth of the group. While most of the patients had an increase in the canal space, there was no change for eight of the patients.

And although the space inside the spinal canal was increased, there was no change in the foraminal space (hole through which the nerve roots pass). Lumbar motion was also unchanged from before to after X-stop implantation.

The authors conclude that the X-stop is a safe but not always effective alternative to decompression surgery. Patients with severe stenosis are less likely to get relief from pain with this treatment.

It is recommended that positional MRI be used to pre-select patients who can benefit the most from X-stop implantation. Those patients who experience pain relief while sitting or when the spine is flexed (bent) seem to have the best results.
Anjali Nandakumar, MBBS, et al. The Increase in Dural Sac Area Is Maintained 2 Years After X-Stop Implantation for the Treatment of Spinal Stenosis with No Significant Alteration in Lumbar Spine Range of Movement. In The Spine Journal. September 2010. Vol. 10. No. 9. Pp. 762-768.