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New Cervical Disc Outperforms Conventional Fusion Surgery at 2 Years: Presented at AAOS

By Roberta Friedman, PhD

SAN FRANCISCO -- March 7, 2008 -- A new disc-replacement device for the cervical spine appears to restore function and improve pain with overall success superior to conventional fusion surgery, according to 2 years of follow-up in a multicentre trial with more than 400 patients.

The Bryan cervical disc replacement scored better than fusion surgery on a primary composite measure of overall success, reported investigator John G. Heller, MD, Professor of Orthopaedic Surgery, Emory University Spine Centre, Atlanta, Georgia.

Dr. Heller reported the study findings here on March 6 at the American Academy of Orthopaedic Surgeons (AAOS) 75th Annual Meeting.

"[Cervical] fusion is a really good operation," Dr. Heller said. "We expected [the Bryan cervical disc replacement] to pay the dividend of preserving range of motion; we didn't think the patients would actually do better than with fusion."

The reduction seen in Neck Disability Index scores with the Bryan disc (P = .030), on the Medical Outcomes Short Form 36 (SF 36) scale, and on a pain visual analog scale, fed into the overall success composite score, to yield 82.7% overall success at 2 years compared with 72.6% for conventional fusion surgery (P = .012). Arm pain improved for both groups of patients. Better improvement in neck pain occurred in the group receiving the Bryan disc (P = .005).

Of patients with single-level cervical disc herniation enrolled in the study, 242 received the Bryan disc device and another 221 were randomly assigned to have anterior cervical discectomy and fusion.

Rate of fusion healing was 94.4%, which is similar to the expected success rate with the conventional procedure. Mean range of motion was 8 degrees for the Bryan device, with patients returning to work 2 weeks sooner after the implant compared with fusion surgery patients (P = .016).

Adverse event rates did not differ between the study groups.

The device consists of a polycarbonate, polyurethane core between titanium shells. A flexible membrane surrounds the inner portion of the disc, which is filled with a lubricant. This membrane is meant to contain any wear debris that forms, and to prevent any soft tissue from growing into the device. The artificial disc is designed to restore a normal range of motion to the neck.

A US Food and Drug Administration panel recommended approval of the Bryan cervical disc last summer.

Funding for this study was provided by Medtronic.


[Presentation title: Bryan Cervical Disc Replacement V. ACDF: Results of the U.S. Prospective Randomized Clinical Trial. Abstract 271]

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