FDA approves new spinal stenosis treatment device

New minimally invasive treatment works with local anesthesia and may yield results comparable to laminectomy.

The FDA has approved a new minimally invasive treatment option for patients with lumbar spinal stenosis.

St. Francis Medical Technologies Inc. announced Nov. 22 that it received marketing clearance for its X Stop Interspinous Process Decompression System as an alternative to standard decompressive lumbar laminectomy. The device, composed of a titanium alloy, is designed to limit lumbar spine extension while keeping open the lower spinal canal that carries nerves to the legs, thereby relieving symptoms.

The FDA approved the device despite a negative recommendation by the Orthopaedic and Rehabilitation Devices Advisory Committee last year. In August 2004, the committee voted 5 to 3 against recommending approving the system for treating mild to moderate lumbar spinal stenosis.

At that time, the company based its premarket approval application (PMA) on a study of 191 patients with mild to moderate lumbar spinal stenosis. One hundred patients were randomly assigned to X Stop treatment and 91 to a control group that received nonoperative therapy involving epidural injections. At 24 months’ follow-up, 58% of X Stop-treated patients and 17% of control patients had clinically significant improvement in symptom severity. Physical function also improved in significantly more X Stop patients — 55% vs. 14% of control patients.

Panel members said data in the company’s PMA failed to show that the device provided significant improvement for most patients or that it would modify physical features of the stenotic spine, as seen during cadaver studies. The committee also said the indications for use were too broad and that the company had insufficient radiographic evidence to prove efficacy, according to an article published in the October 2004 issue of Orthopedics Today.

However, according to the company, clinical studies show X Stop-treated patients achieved results equal to those who underwent laminectomy, but with less blood loss and fewer complications. Patients treated with the X Stop procedure also experienced immediate symptom relief and a recovery period of about two weeks, according to a press release from St. Mary’s Medical Center, which developed the device and led clinical trials.

The X Stop is inserted through a small incision and placed posterior to neural structures, minimizing the risk of neural injury. The procedure can be performed on an inpatient basis using local anesthesia and carries a minimal risk of systemic and local complications. It does not result in fusion and is reversible, allowing it to be used as a first-line treatment without compromising possible alternatives, including laminectomy, according to the company press release.

“Unlike laminectomy, the X Stop procedure does not require general anesthesia, making it a more viable option for those with lumbar spinal stenosis who cannot tolerate general anesthesia as a result of their age or other health conditions,” James F. Zucherman, MD, co-inventor of the X Stop device and medical director of St. Mary’s Spine Center in San Francisco, said in the release. “This new procedure fills a gap in the continuum of care that, until now, required patients to make the leap from conservative therapies, such as analgesics and injections, straight to invasive surgery.”

The X Stop was approved in Europe and Japan in 2001 and has since been implanted in more than 4000 patients. St. Mary’s Medical Center, located in San Francisco, will serve as the primary training center for U.S. physicians.

For more information:

Rapp S. FDA vote: Interspinous distraction device not recommended for approval. Orthopedics Today. 2004;24:1.