June 21, 2004 — 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," was
presented 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.
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