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Artificial Disc Now Available, But Is It Better Than Other Therapies?

MANAGED CARE October 2007. © MediMedia USA
Tomorrow's Medicine

Artificial Disc Now Available, But Is It Better Than Other Therapies?

The Prestige Cervical Disc system can replace a single disc from C3 to C7 and gives people with cervical disc disease another viable treatment option
Thomas Morrow, MD
MANAGED CARE October 2007. ©MediMedia USA

The Prestige Cervical Disc system can replace a single disc from C3 to C7 and gives people with cervical disc disease another viable treatment option

Thomas Morrow, MD

In July, the FDA approved the marketing of the Prestige Cervical Disc made by Medtronic Sofamor Danek of Memphis. This is the first artificial cervical disc approved for the treatment of cervical degenerative disc disease and follows the approval of discs for use in the lumbar spine. The Prestige system was granted expedited review status in May 2006 because the FDA believed that an artificial disc might offer some patients an alternative to cervical fusion. Interestingly, this technology has already been available outside the United States — the device has been implanted in about 15,000 people.

The FDA approved the Prestige system as a class 3 device based on a randomized controlled study of 541 patients who were evaluated for 24 months after surgery. Roughly half were implanted with the artificial disc. The control group underwent traditional decompression and fusion.

Effective and safe

The Prestige system was deemed as effective and safe as the commonly performed decompression and cervical fusion.

It can be used to replace a single disc from C3 to C7 in skeletally mature patients who have cervical degenerative disc disease and have been diagnosed as either intractable radiculopathy, myelopathy with symptomatic nerve root, or spinal cord compression. The diagnosis must be confirmed with patient history and radiographic studies.

The Prestige system is implanted via an open anterior incision about one inch long. The system is a two-piece articulating stainless steel device made up of a superior component that contains a "ball" and an inferior component that incorporates a "trough."

10 different sizes

The ball can slide in the trough to allow flexion/extension of the components. Each component also has two screws that are placed in the adjacent bone of the vertebrae and a lock screw to prevent the screws from backing out once in place.

The Prestige cervical disc system comes in 10 different sizes to accommodate a variety of vertebral lengths. It should provide significant pain relief and improved function. It is contraindicated in patients with active infection or allergy to stainless steel.

Potential complications and risks include allergic reaction to the implant material, loosening, moving, or bending of the implant, wound infections, neck or arm pain, difficulty swallowing, impairment or change in speech, nerve or spinal cord injury, numbness or tingling in the extremities, tearing of the dura of the spinal cord, loss of motion or fusion at the treated cervical level, progression of disease at other cervical disc levels, bleeding, blood clots, swelling, reactions to anesthesia, inability to resume activities of normal daily living, and other surgical complications such as infections.

No deaths

Although death is mentioned as a potential complication, there were no deaths in the investigational group. Three control group deaths were reported, all attributed to cardiac disease.

The overall success rate was statistically noninferior to fusion with bone graft and plate stabilization for the treatment of cervical degenerative disc disease from C3 to C7. The safety profile demonstrated that the Prestige Cervical Disc was as safe as the traditional surgery in regard to adverse events and the need for second surgeries.

Of note is that the approval is limited to "claims of noninferiority." The manufacturer was hoping for a claim of superiority compared to traditional surgery, but the FDA deemed the evidence insufficient. The FDA forbids the manufacturer from suggesting that preserving motion at one segment prevents the adjacent discs from developing disease.

This particular type of stainless steel material has been used in spinal surgery for many years, so no post-approval "particulate" study was needed.

Post-approval study

The manufacturer has agreed to perform a seven-year post-approval study to evaluate the longer-term safety and effectiveness of the Prestige Cervical Disc. This study will include the active and control patients from the pivotal trial as well as patients who received the device as part of the continued access study arm.

Data will be collected at three, five, and seven years after surgery and will include a neck disability index score, radiographic studies, and neurological status. The manufacturer will collect all adverse events and will submit the data annually to the FDA. In addition, the sponsor has agreed to conduct a five-year enhanced surveillance study of the Prestige Cervical Disc to more fully characterize adverse events when the device is used in a broader "uncontrolled" patient population.

Managed care implications

To reiterate, the FDA clearly stated that the manufacturer cannot claim superior results over traditional disc/fusion surgery and made an extra comment about the lack of data to support prevention of future disease of the neck. The device lists for $4,450 in addition to the costs for the surgery. Given these seemingly significant FDA rulings, how will managed care react?

Will prior authorization processes be implemented? With the absence of a superiority claim, will the Prestige system be considered "not-medically necessary" and have payments denied?

Since it is a device that is used in a hospital setting, will there be contractual issues with the billed charges versus reimbursed amounts? Will hospitals accept the use of this device given the risk of nonreimbursed expenses? Are there any cost offsets in other components of the surgery or recovery to make this cost-neutral?

Will managed care decision makers ask for economic studies or data similar to what they require for new drugs? Will patient demand be there given the limited approval?

These and other questions will face us as we continue to face the rapid technological development of Tomorrow's Medicine!

Thomas Morrow, MD, is the immediate past president of the National Association of Managed Care Physicians. He has 21 years of managed care experience at the payer or health plan level.
The author is a director in the value-based health department at Genentech Inc. During the last three years, before taking the Genentech position, he received honoraria or other financial benefits from: Amgen, Amylin Pharmaceuticals, AstraZeneca, Biogen Idec, Centocor, Galderma, GlaxoSmithKline, Johnson & Johnson, Merck, Novartis, Novo Nordisk, Pfizer, Procter & Gamble, Q-Med, Sanofi-Aventis, Teva Pharmaceuticals Industries, UCB, and Wyeth. The views expressed in Tomorrow's Medicine are the author's alone.

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