UCSF Orthopedic Surgeons Test Artificial Back Disc

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Source:   University Of California - San Francisco

(http://www.ucsf.edu/)

Date:   Posted 8/1/2002

UCSF Orthopedic Surgeons Test Artificial Back Disc

UCSF Medical Center orthopedic surgeons are investigating the effectiveness

of an implant that may replace damaged lower back discs. European patients

who have received the stainless steel and plastic assembly in place of

degenerated discs have reported significant improvement in back and leg pain

after a minimum of seven years of follow-up, according to the UCSF

investigators.

" In European clinical trials, the implant alleviated disc-related lower back

pain while maintaining spine mobility ­ and eliminated the need for fusion

of the lower spine, " said S. Bradford, MD, UCSF professor of

orthopedic surgery and lead investigator of the UCSF study.

UCSF Medical Center is one of 13 centers currently evaluating Prosdisc®,

which replaces discs damaged by degeneration, bulging, herniation, or

thinning. The objective of the randomized clinical trial, which will enroll

approximately 510 patients over four years, is to compare the safety and

effectiveness of the Prodisc® implant to spinal fusion surgery. In fusion,

the mainstay of surgical treatment for low back pain caused by degenerative

disc disease (DDD), surgeons use rods and screws attached to the bones of

the spine to hold them until the bones heal together.

While fusion of the lumbar spine has increased at the highest rate of any

spinal procedure in the last ten years, advisability for patients,

techniques and results remain controversial and unclear, according to

Bradford. The ability of the bone to heal or fuse varies. In addition,

spinal fusion at one or more levels can cause stiffness and decreased motion

in the spine and more stress to be transferred to adjacent levels of the

spine. Consequently, not all patients have a successful outcome, he said.

" Most important, fusion is not targeted toward restoration of normal

structure and function, " said Bradford. " This prospective, randomized study

will tell us is if the Prodisc® can eliminate back pain by preserving or

restoring motion in the spine, restoring the structure and height of damaged

vertebrae, and restoring the normal bio-mechanics of the lumbar spine. "

The artificial disc device, developed in France in the late 1980s, has two

porous cobalt-chrome plates, with stabilizing keels that integrate into

adjacent vertebrae, and a polyethylene ball-bearing core. The core functions

on a ball-and-socket principle to fulfill the role of healthy discs -- which

permit limited motion and flexibility, while maintaining stability in

specific segments of the spine and absorbing and distributing load.

The Prodisc® implants are suited for patients with degenerative disc disease

at one or two levels of the spine. Patients should be between the ages of 18

and 60 and are eligible if they have failed at least six months of

conservative therapy. Some patients will receive the Prodisc®, while others

will receive the currently accepted treatment, spinal fusion.

Back pain is the most common ailment of the working-age adult, affecting

over four million individuals each year in the United States. It is

estimated that treatment of lower back pain in the United States costs more

than $100 billion a year. While most acute episodes of low back pain respond

well to non-operative treatment, the management of chronic low back pain

remains a difficult challenge, according to Bradford.

The rate of back surgeries, including fusion of the spine, has increased by

more than 600 percent between 1979 and 1990. In addition to spinal fusion,

current treatments also include disc excision (discectomy) and the use of

injections, electrothermal therapies, and implanted neural stimulators and

medication dispensers.

In addition to artificial disc replacement, researchers in the spinal

disorders division at UCSF Medical Center are also investigating disc

regeneration using techniques of cellular and molecular biology and

intervertebral disc arthroplasty (artificial joint creation). This may

include replacing only the center of the disc, the nucleus, according to the

UCSF researchers.

The Prodisc® prosthesis, manufactured by Spine Solutions, Inc. of New York,

is one of two similar devices being investigated. A separate study is

analyzing the effectiveness of the SB Charite III Dynamic Disc Spacer,

manufactured by the Link Spine Group in Branford Connecticut. This device

was developed in the mid-1980s at the Berlin Charite Clinic in Germany.

Additional investigators on the UCSF clinical trial of Prodisc® include:

Serena Hu, MD, UCSF associate professor of orthopedic surgery; Sigurd H.

Berven, MD, UCSF assistant professor of orthopedic surgery; Bobby K. B. Tay,

MD, UCSF assistant professor of orthopedic surgery; and Vedat Deviren, MD,

UCSF assistant professor of orthopedic surgery.