No matter how good the original version of a device is the second-generation version is, by definition, better.

Medtronic (Minneapolis), for example, has just launched its X-Stop PEEK IPD system, a new-and-improved version of its X-Stop interspinous process decompression (IPD) device. The original device — which received FDA approval in 2005 — was billed as a "middle-of-the-road measure" between non-surgical treatment and a much more invasive lumbar laminectomy. The second-generation version of X-Stop also offers a minimally invasive treatment for symptoms of lumbar spinal stenosis (LSS), plus changes in material, shape and available sizes.

Medtronic plans to introduce the X-Stop PEEK system this week at the 23rd annual meeting of the North American Spine Society (Burr Ridge, Illinois) in Toronto.

The device was developed by St. Francis Medical Technologies (Alameda, California), which was acquired last year by Kyphon (Sunnyvale, California), which in turn was scooped up by Medtronic in a $4.2 billion deal.

The X-Stop PEEK IPD "is the only FDA-approved IPD device in the U.S. to offer PEEK," Denise Franklin, a spokeswoman for Medtronic's Kyphon business, told Medical Device Daily.

PEEK, or polyetheretherketone polymer, is a biocompatible and radiolucent material, Franklin said. Medtronic said it would continue to offer both the titanium alloy and the PEEK versions of the X-Stop system to accommodate surgeon preference. In addition, the device also features a new elliptical shape and is now available in a larger size.

According to Medtronic, LSS is the most common reason for back surgery in people over 65 in the U.S. This degenerative condition can cause compression of the spinal cord and nerves in the lower back, leading to back and leg pain or numbness that can affect mobility, the company noted. An estimated 875,000 Americans are diagnosed with LSS each year, and more than two million Americans currently suffer from this disease, Medtronic said.

"We are extremely excited to offer the 3,200 U.S. surgeons trained so far on the X-Stop procedure the added benefits of the X-Stop PEEK system," said Robert White, president of Kyphon products in the Spinal and Biologics business at Medtronic. "Many surgeons will welcome the properties of PEEK, the elliptical shape of the new device, and the addition of a 16mm size implant to our X-Stop product line."

In the new system, the body of the device that is implanted between the spinous processes to prevent the pinching of the nerves is composed of a PEEK outer ring, with the remainder of the device made of titanium alloy. The original device is made completely of titanium alloy.

The X-Stop PEEK implant also has been designed to be more elliptical than the first-generation device, Medtronic said. This shape increases the contact area with bone by 30% compared to an implant of circular cross section. There is a broader load-bearing surface for distributing loads to the spinous processes, thereby decreasing contact pressures, the company said.

Medtronic has also extended its product offering of X-Stop implant sizes with the addition of the 16mm implant in the PEEK system. Franklin said spine surgeons had requested the larger implant size for some of their patients.

With a second-generation version of this device now available in the U.S. it may be hard to believe that the history of the X-Stop began with an FDA panel turndown. In a 5-3 vote in late 2004, the Orthopedic Rehabilitation Devices Panel of the FDA's Medical Devices Advisory Committee voted against recommending approval of the X-Stop system, even though many of the panelists praised the device's "innovative design." Discrepancies in trial data raised enough doubt to keep the X-Stop from being recommended for approval that year (Medical Device Daily, Sept. 2, 2004).

But St. Francis was persistent and in November 2005 — more than a year after the FDA panel turndown — the agency approved the device for the treatment of LSS (MDD, Nov. 28, 2005).

The X-Stop PEEK system has been in clinical use in Europe since 2004. St. Francis first launched the PEEK version of the device after it was approved for European markets in March of that year.

While the X-Stop PEEK system is the only FDA-approved IPD device in the U.S. to offer PEEK, a similar device is already available in Europe from Pioneer BV (Driebergen, the Netherlands), the European subsidiary of Pioneer Surgical Technology (Marquette, Michigan). Pioneer's BacJac interspinous decompression system was launched in Europe in May during the International SpineWeek meeting in Geneva, Switzerland (MDD, May 28, 2008).

Like the X-Stop PEEK system, the BacJac system is considered to be a minimally invasive approach and is made of PEEK. Something else the two devices have in common — Lex Giltaij, MD. Giltaij, VP Europe & business development at Pioneer Surgical, was formerly the head of European business for St. Francis. During SpineWeek in May Giltaij said most of his team followed him to Pioneer after Kyphon acquired St. Francis (MDD, May 30, 2008).