Metal-on-metal disc, effective alternative to spinal fusion

The neck and arm pain caused by degenerative cervical (neck) disc disease may be eliminated by replacing the problem disc with a metal-on-metal artificial disc, according to the results of a study presented at the annual meeting of the American Association of Neurological Surgeons/CNS Section on Disorders of the Spine & Peripheral Nerves.

"Implanting this device in the neck may be an effective alternative to spinal fusion," said Dr. Russ P. Nockels, associate professor and vice chair, Department of Neurological Surgery, Loyola University Chicago Stritch School of Medicine, Maywood, Ill.

Nockels, who presented the findings, is principal investigator for the Loyola site, which is a participant in a national clinical trial.

"The prosthesis simulates the function of a natural cervical disc," said Nockels.

Researchers tested the disc in the laboratory for mechanical stability under extreme forces.

"The disc is strong enough to withstand sudden movement and support the head," said Nockels, chief of the Division of Neurological Spinal Disorder and director of the Spinal Cord Injury Repair Laboratory, Loyola University Health System, Maywood, Ill. "Patients are able to move their head up and down, and from side to side."

More than half of people over age 40 have cervical disc disease, characterized by degenerative changes in the upper spine.

Symptoms include pain radiating down the arm and numbness, in addition to neck pain. As a result, many people have difficulty sleeping.

Natural discs are gel-like cushions that act as shock absorbers between each vertebra in the spine. Herniation, resulting from disc degeneration, injury or heavy lifting, can occur when a portion of the disc is pushed out of place and presses on adjacent nerve endings.

Cervical discs are located between the seven vertebrae of the neck. Discs dehydrate and shrink over time, producing areas where bone touches bone. Cervical disk disease is expected to increase substantially as baby boomers age.

"The only approved method today to help cervical disc disease patients is to clear away the troublesome bone spurs and disc material and fuse the cervical vertebrae together," said Nockels. "This permanent fusion of bone eliminates normal movement between the fused vertebrae. It also may put added stress on the vertebrae above and below the fusion."

The PRESTIGE TMArtificial Cervical Disc consists of two, stainless-steel components that are attached to the vertebrae with screws. The components are designed to act as a pivot point, which may allow the spine to move more naturally.