FDA advisory panel recommends artificial cervical disc for approval with conditions

Panel members questioned the superiority claims for the device and long-term results of its polyurethane materials.

The Orthopedic and Rehabilitation Devices advisory panel to the FDA voted 7-1 to recommend approval of the Bryan Total Cervical Disc Prosthesis. However, the recommendation is subject to several conditions.

The advisory panel meeting, which was held yesterday, marked the second time an artifical cervical disc reached the panel for review. Device sponsors presented the results of a prospective, randomized trial comparing anterior cervical discectomy and fusion (ACDF) to single-level procedures performed with the Bryan prosthesis [Medtronic Sofamor Danek], a device constructed of two titanium shells and retention wires, a polyurethane nucleus and sheath. The multicenter study included 12-month follow-up of 300 patients and 24-month follow-up of 431 patients.

The study defined overall success using the rate of improvement in the Neck Disability Index and the maintenance or improvement in neurological status without either adverse events or secondary surgery.

At 24 months follow-up, investigators found an 80.6% overall success rate among patients implanted with the Bryan prosthesis vs. 70.7% among patients treated with ACDF. In addition, a Bayesian analysis showed an almost 100% posterior probability of non-inferiority and a 96.9% probability for superiority in favor of the device. Therefore, the device sponsors concluded that the Bryan prosthesis showed an overall success rate that was non-inferior and superior to ACDF.

However, the panel questioned the sponsor's statements regarding superiority.

"I think the sponsors presented good information about a well-constructed study with an appropriate control group," said Edward N. Hanley, MD, a panel member and orthopedic surgeon in Charlotte, N.C.

"I do not agree with the claims of showing superiority but, overall, I think that it does demonstrate to be equivalent and in the long run may potentially show some benefits on some theoretical basis," he said.

Hanley's comments echoed the concerns of other panel members regarding the long-term benefits of the polyurethane.

"I am concerned that it may deteriorate over time and may not mechanically function as well as it should. But, overall, I think that the information provided was satisfactory and I think that the panel has constructed an appropriate group of recommendations for the FDA to follow," Hanley said.

The panel recommended seven conditions of approval, including:

that the product literature include no claims of superiority for the device;
changing the indications from the 'treatment of degenerative disc disease in skeletally mature patients' to 'an alternative to reconstruction after single-level decompression for cervical radiculopathy between C3 and C7;' and,
that the sponsor conduct a 10-year post-marketing approval study evaluating rates of heterotopic ossification, kyphosis, explantation and motion at adjacent and treated levels.

In addition, the FDA recently approved Medtronic's Prestige Cervical Disc, making it the first cervical artifical disc cleared for use in the U.S., according to press release from Medtronic.

However, the approval requires Medtronic to perform a 7-year post-approval study and a 5-year enhanced surveillance study, the release said.

The Prestige device is indicated as treatment for patients with cervical degenerative disc disease as an alternative to cervical fusion, and it may allow for motion at the treated level, according to the release.

In a study of 541 patients, investigators found that the Prestige device yielded better overall success and better neurological success at 24 months compared to spinal fusion. The study also showed equivalent Neck Disability Index measures and fewer revision surgeries among patients who received the Prestige device, the release said.