Spinal fusion — technically called anterior cervical disectomy and fusion — has been the long-time standard-of-care treatment for degenerative spine disease in the cervical (neck) area.

But spinal fusion in the cervical area is likely to soon get a sort of double-team competition with the roll-out this week by Medtronic (Minneapolis) of the Prestige artificial cervical disc, made by the company’s Medtronic Spinal and Biologics (Memphis, Tennessee) unit — and, poised for approval and roll-out, the company’s Bryan Cervical Device, based on a panel recommendation.

The competition might be described as the “neck-and-neck” type (one might say) since Medtronic’s marketing effort will be to convince surgeons and patients that implantation of an artificial disc is superior to fusion, but a claim not allowed by the FDA in granting approval of the Prestige — and unikely to be granted for the Bryan either.

Apart from any claims of superiority, Ken Burkus, MD, an orthopedic surgeon at the Hughston Clinic (Columbus, Georgia) — and a participant in the clinical trial for the Prestige disc — told Medical Device Daily: “They are both very good discs. This technology is a major breakthrough because, instead of the fusion method, we now have a motion preserving procedure.”

And apart from final clinical outcomes, Burkus noted that spinal fusion requires weeks of healing, compared to the implant of artificial discs enabling patients to return to normal activities sooner without restrictions or the need for braces or collars.

Medtronic got regulatory boosts for both devices last month, first reporting FDA approval of the Prestige disc, followed by panel recommendation for approval of the Bryan (MDD, July 18, 2007/July 19, 2007).

The Prestige disc — which won an advisory panel thumbs-up last September (MDD, Sept. 21, 2006) — is made from a titanium/ceramic composite with enhanced wear characteristics and improved imaging properties in laboratory testing, according to the company. The device incorporates two articulating components, a ball on top and a trough on the bottom that are attached to the vertebral bodies. This ball-and-trough configuration is designed to help provide for replication of normal physiological motion. Dual stabilization rails and a plasma spray coating on each component are designed to help encourage biological fixation and long-term stability.

The Prestige was studied in a multi-center, randomized trial to assess safety and efficacy, based on comparisons between data collected from patients with single-level symptomatic cervical DDD at one level between C3-C7. Regulatory application to the FDA was based on a study of 276 patients who received the Prestige device and a control group of 265 patients who received an anterior plated surgical fusion utilizing bone graft and plate stabilization.

The company billed the 541-patient study as the largest ever conducted for an artificial disc for the cervical application.

About 15,000 people outside the U.S. have already been implanted with the Prestige, according to Medtronic.

The Bryan disc contains a rubber center and is composite-type artificial disc designed with a low friction, wear resistant, elastic nucleus with two anatomically shaped metal plates. A flexible membrane forms a sealed space and contains a lubricant to reduce friction and wear and tear. The implant allows for normal range of motion and comes in five sizes.

Noting that the Bryan has received a panel recommendation for approval, Burkus said that this disc “should be ready for commercialization within nine months to a year.”

But the question remains, are these discs better than surgical fusion methods?

The FDA is sending a resounding answer of “not exactly” to the med-tech goliath.

Medtronic was seeking a claim that the Prestige is superior to surgery, but the FDA declined to endorse that claim. The company can only say that the device is “as safe and effective” as surgery.

The company studies also claim that the disc is 10% more effective than fusion surgery, but FDA reviewers say further analyses of the data show the device may not be that effective.

In its approaches to the advisory panels and the agency, Medtronic has sought labeling that would say the devices are “superior” to most fusion methods.

The FDA panel had given its recommendation, with conditions, including the requirement for post-marketing surveillance and the stipulation that the company cannot claim that the Prestige is superior to spinal fusion, a recommendation that the claim be limited to “non-inferiority.” (MDD June 18, 2007).

In considering the Bryan cervical disc, the advisory panel asked that the company conduct two kinds of trials: one, to examine reports of kidney problems seen in some rodent models; and two, a post-approval study to examine spinal curvature and a condition known as heterotopic ossification.

Medtronic’s discs are not the only ones likely to be in competition with cervical fusion procedures.

LDR Spine (Austin, Texas) has developed the Mobi-C cervical artificial disc. The company last year obtained approval for an investigational device exemption from the FDA, allowing it to conduct a pivotal human clinical trial to investigate the safety and effectiveness of the Mobi-C disc (MDD, Feb. 1, 2006). The Texas Back Institute (Dallas), which bills itself as the largest freestanding spine specialty clinic in the U.S., is the leading clinical site for the investigational study, which will follow up to 600 patients for the two years. The Mobi-C is already available in 20 countries throughout Europe and Asia.

And SpinalMotion (Mountain View, California) late last year reported “significant progress” in U.S.-based investigational device exemption clinical trials of its Kineflex lumbar disc and Kineflex C cervical disc implants (MDD, Sept.28, 2006).