Study Finds New Minimally Invasive X STOP Procedure Significantly More Effective Than Current Therapies for Common Cause of Low Back Pain.

SAN FRANCISCO -- Journal of Neurosurgery: Spine Publishes Clinical Results to Support X STOP for the Treatment of Degenerative Spondylolisthesis 

According to a randomized, controlled, multicenter study published in the June issue of Journal of Neurosurgery: Spine, a prestigious scientific journal published by the American Association of Neurological Surgeons, patients suffering from degenerative lumbar spinal stenosis (LSS) with spondylolisthesis showed significantly greater improvement with a new, minimally invasive procedure, the X STOP(R) Interspinous Process Decompression (IPD(R)) System ("X STOP"), than with steroid injections and other non-operative treatments during a two-year follow-up period. Moreover, overall clinical success with steroid injections and other non-operative care was found to be only 12.9 percent.

"The results from this study are significant for patients suffering from LSS with degenerative spondylolisthesis because these patients historically required invasive procedures such as decompression and fusion. Based on these results, patients now have a minimally invasive option that is shown to provide better outcomes than their current therapeutic alternatives," said Paul Anderson, M.D., associate professor, Department of Orthopedic Surgery & Rehabilitation, University of Wisconsin - Madison Hospital and lead investigator of the study.

Background on Degenerative Spondylolisthesis:

Lumbar spinal stenosis (LSS) is a common spinal problem suffered mainly by the middle-aged and elderly population, and results from a narrowing in the lumbar spinal canal that carries nerves to the legs. As this space in the lower spine shrinks, the nerves that go through it are squeezed. Degenerative spondylolisthesis, which can be associated with LSS, is a slippage of one vertebra over another, which contributes to increased pressure on the spinal nerves and results in pain in the lower back, buttocks or legs. Degenerative spondylolisthesis is a common cause of low back pain -- according to the Agency for Healthcare Research and Quality (AHRQ), "11 percent ... of men and 25 percent ... of women developed degenerative vertebral slippage over their lifetimes."(1)

Narrowing of the lumbar canal has many potential causes and can be congenital or acquired. In most cases, stenosis of the lumbar canal is attributed to degenerative or arthritic changes of the intervertebral discs, ligaments and vertebral joints surrounding the lumbar canal.

"The publication of the trial results in a prestigious publication such as Journal of Neurosurgery: Spine provides clear validation of the importance of this study," said Kevin Sidow, president and chief executive officer of St. Francis Medical Technologies. "These study results will further our ability to work with spine surgeons to provide minimally invasive solutions to patients suffering from degenerative spine diseases."

Methodology:

The current study was on a selected cohort (n=75) from a randomized, controlled multicenter trial (n=191) comparing the outcomes of neurogenic intermittent claudication (NIC) patients treated with the X STOP with patients treated non-operatively. Of the 191 LSS patients enrolled in the X STOP pivotal trial from multiple centers, 75 had degenerative spondylolisthesis up to grade 1 (on a scale of 1 to 4). The patients were randomly assigned to the X STOP procedure or non-operative treatment. Of the 75 patients who had spondylolisthesis 42 received the X STOP and 33 received steroid injections and other non-operative care. Prior to treatment, patients completed several outcome instruments (described below), and completed the same instruments in follow-up visits at six weeks, six months, 12 months and 24 months.

All centers had Institutional Review Board (IRB) approval and were approved as Investigational Study Centers by the Food and Drug Administration (FDA), as this study was part of the pivotal trial to evaluate the safety and efficacy of the X STOP.

To be included in the study, patients had to be above the age of 50, had their symptoms relieved by sitting or flexion and had to have completed at least six months of non-operative treatment such as analgesics, steroid injections or physical therapy. Patients were excluded if they could not walk at least 50 feet and/or were unable to sit at least 50 minutes. Additionally, a patient was excluded if they had significant instability of the lumbar spine, e.g., isthmic spondylolisthesis or degenerative spondylolisthesis greater than grade 1 (on a scale of 1 to 4).

Study Results:

The study yielded the following results:

--Overall clinical success at the two-year follow-up occurred in 63.4 percent of X STOP patients and only 12.9 percent of patients who received non-operative care, and this difference was highly statistically significant. Moreover, the poor results from non-operative care seen in this study are surprising given the number of spondylolisthesis patients currently being treated with epidural steroids.

--Patient satisfaction was significantly higher in patients who received the X STOP.

--Statistically significant improvement in ZCQ at all follow-up time periods, compared to the non-operative group, which experienced no significant improvement in ZCQ scores. ZCQ is the Zurich Claudication Questionnaire, a validated outcomes instrument specific to lumbar spinal stenosis. ZCQ success in the trial was defined as improvement in physical function, improvement in symptom severity and patient satisfied or somewhat satisfied with therapy.

--Statistically significant improvement in SF-36, compared to no change from baseline in the non-operative group. SF-36 is the Medical Outcomes Study Short Form.

About the X STOP:

The X STOP(R) Interspinous Process Decompression (IPD(R)) System ("X STOP") is a titanium alloy implant that was approved by the FDA in November 2005 as the first and only non-fusion treatment to improve symptom severity and physical function for patients with LSS. X STOP fills a gap in the continuum of care for LSS sufferers that, until now, required patients to leap from conservative therapies, such as analgesics and injections, straight to laminectomy, an invasive procedure that is considered the current surgical standard of care. Clinically proven to relieve patients' symptoms, the X STOP procedure is well poised to become the first-line surgical intervention for LSS patients.

Inserted through a small incision, the X STOP is placed between two bones called spinous processes of the symptomatic discs in the low back. The X STOP is designed to limit extension of the lumbar spine, and keep open the canal in the lower spine that carries nerves to the legs, thereby relieving symptoms.

The device can be surgically implanted in a minimally invasive procedure that is typically performed with local anesthesia in less than an hour. As it is not fixed to any bony structures, the X STOP procedure does not result in fusion and is completely reversible without compromising any therapeutic alternatives, including laminectomy.

The X STOP has been available in Europe and Japan since 2001, and more than 7,000 X STOP devices have been implanted worldwide.

About St. Francis Medical Technologies' Clinical Leadership:

The results of the FDA pivotal trial that led to the FDA approval of the X STOP in November 2005, as well as other clinical studies, have been published in prestigious journals.

Heijnen, S. and F. Kramer, Spinal Distraction as Therapy for Lumbar Spinal Stenosis - The First Results. Dutch Orthopedic Journal, 2005: p. 199-203.

Lee, J., et al., An interspinous process distractor (X STOP) for lumbar spinal stenosis in elderly patients: preliminary experiences in 10 consecutive cases. J Spinal Disord Tech, 2004. 17(1): p. 72-7; discussion 78.

Zucherman, J.F., et al., A Multicenter, Prospective, Randomized Trial Evaluating the X STOP Interspinous Process Decompression System for the Treatment of Neurogenic Intermittent Claudication: Two-Year Follow-Up Results. Spine, 2005. 30(12): p. 1351-1358.

Siddiqui, M., et al., The positional magnetic resonance imaging changes in the lumbar spine following insertion of a novel interspinous process distraction device. Spine, 2005. 30(23): p. 2677-82.

About St. Francis Medical Technologies:

St. Francis Medical Technologies is a privately held company based in Alameda, Calif., engaged in the discovery, development, manufacturing and marketing of novel treatments for degenerative spinal disorders worldwide. In November 2005, St. Francis received FDA approval for the X STOP, the first FDA-approved interspinous process implant to treat Lumbar Spinal Stenosis (LSS), a degenerative spinal disorder that may affect over two million Americans. As a result, patients and healthcare professionals finally have a safe and effective alternative to more aggressive, riskier procedures. For more information, please visit: www.sfmt.com.

(1) http://www.ahrq.gov/clinic/epcsums/stenosum.htm