Efficacy of Artificial Disc Implantation for Treatment of Degenerative Disc Disease

Newswise — Degenerative disc disease is a disorder that may cause low back pain, which affects 80 percent of adults in their lifetimes. Neurosurgeons recently conducted studies to determine whether new functional intervertebral cervical disc prostheses can provide relief from neurological symptoms and signs, improve a patient's ability to perform activities of daily living, decrease pain, and maintain stability and segmental motion of the neck. The study, "Prospective-Randomized, Multicenter Analysis of the Efficacy of Artificial Cervical Disc Prosthesis for the Relief of Cervical Radiculopathy," will be presented from 11:35 to 11:50 a.m. on Tuesday, May 4, 2004, during the 72nd Annual Meeting of the American Association of Neurological Surgeons in Orlando, Florida. The study will be presented by Richard G. Fessler, MD; Stephen M. Papadopoulos, MD; Jan Goffin, MD; and John Heller, MD.

The medical community has sought ways to alleviate the added stress on a patient's adjacent discs following cervical spine (neck) fusion, a surgical treatment designed to combat degenerative disc disease. The study's authors hypothesized that replacement of a failed intervertebral disc with a functional disc prosthesis can offer the same benefits as fusion, while preserving motion and thereby protecting the adjacent discs from the additional stresses associated with fusion.

Patients who were enrolled in the 2000 and 2001 studies suffered from single-level and bi-level degenerative disc disease of the cervical spine. Degenerative disc disease is the breakdown of the cervical spinal discs, which serve as cushions between the spinal vertebrae. The patients selected for the study had not responded to conservative treatment (rest, soft collar, physiotherapy and medications) throughout the six weeks prior to the study.

Patients in the study underwent implantation with the Bryan cervical prosthesis after a standard anterior cervical-discectomy (surgical removal of an intervertebral disc) was performed. At scheduled follow-up periods, each patient's pain and neurologic function were evaluated, and the range of motion was measured, all in an effort to characterize the overall effectiveness of the device. The cervical disc implantation procedure is safe and the patients recover quickly.

Researchers conducted two separate studies to evaluate their initial predictions. In the single-level study a total of 103 patients underwent the implantation surgery and were followed-up and evaluated. Of the 92 patients with complete clinical data at the six-month follow up, 83 of the patients were classified as excellent, good or fair. In the single-level study, 44 out of 49 patients (90 percent) evaluated at the two-year follow-up, 76 out of 89 patients (86 percent) evaluated at one-year follow-up and 83 out of 92 patients (90 percent) evaluated at six-month follow-up, were deemed a clinical success.

In the bi-level study, 43 patients underwent the implantation surgery and were followed-up and evaluated. At one-year follow-up 24 out of 25 patients (96 percent) were evaluated and at six-month follow-up, 27 out of 33 patients evaluated (82 percent) were deemed a clinical success.

In addition, two degrees or greater is the identified threshold that accurately establishes motion without the question of measurement error. At one-year follow-up, 88 percent of the patients that participated in the bi-level study had used motion equal to or greater than two degrees. At the two-year follow-up, 93 percent of the patients in the single-level study used motion equal to or greater than two degrees.

"Our data clearly reveals that properly placed devices do not migrate, and the device does allow for segmental motion," said Richard G. Fessler, MD, a lead author of the study. "The implantation of the device alleviates pain and improves function based on neurologic signs and symptoms."

The authors note that at least five years of follow-up will be necessary to evaluate the long-term functionality and protection offered by the prosthesis.

Founded in 1931 as the Harvey Cushing Society, the American Association of Neurological Surgeons (AANS) is a scientific and educational association with more than 6,500 members worldwide. The AANS is dedicated to advancing the specialty of neurological surgery in order to provide the highest quality of neurosurgical care to the public. All active members of the AANS are certified by the American Board of Neurological Surgery, the Royal College of Physicians and Surgeons (Neurosurgery) of Canada or the Mexican Council of Neurological Surgery, AC. Neurological surgery is the medical specialty concerned with the prevention, diagnosis, treatment and rehabilitation of disorders that affect the entire nervous system including the spinal column, spinal cord, brain and peripheral nerves.