Help for a pain in the neck
The spine, that slender column of 34 bones, suffers its share of wear and tear. And the cervical spine -- the upper seven bones, plus the discs between them -- is particularly taxed.
“The warranty on the cervical spine runs out at about age 20,” says Dr. Russ P. Nockels, of Loyola University Chicago Stritch School of Medicine, only partially in jest. “We use the cervical spine constantly -- leaning on it and flexing it forward.”
Over time, the gel-like discs that act as cushions between the bones, or vertebrae, can shrink and lose their shock-absorbing ability. Medication and physical therapy can sometimes treat the resulting pain and limited movement in the upper back, neck and shoulder. But each year about 200,000 Americans undergo surgery, usually spinal fusion, as a remedy for what is known as degenerative disc disease.
Spinal fusion uses a bone graft and sometimes a metal plate to attach two vertebrae and prevent them from rubbing against each other. The procedure often eases the pain caused by the displacement of the damaged disc, says Nockels, an associate professor and vice chairman of the department of neurological surgery at Loyola, but it can limit the neck’s range of motion.
An artificial disc could be a better option. It actually would replace the worn-out disc, allowing movement.
“The cervical spine is a vital structure,” says Nockels. “It doesn’t make sense to arrest motion.”
One product currently being studied, called the Prestige Artificial Cervical Disc, consists of two pieces of stainless steel attached to the vertebrae with screws. The components are designed to pivot and, in studies so far, appear to stay in place, alleviating pain.
“Patients with artificial discs are immediately active again,” Nockels says. “Within days, they can resume their normal activities.”
Data presented in March at a meeting of the American Assn. of Neurological Surgeons showed that the disc could withstand 10 times the stress that would normally be generated in the neck.
Another product, called the Bryan disc, is also being studied. It includes a rubbery surface that more closely mimics a natural disc than the Prestige disc, although the Prestige disc is designed to maximize movement. Both discs are made by Medtronic Inc., of Minneapolis, and are still being evaluated for safety and efficacy.
Researchers don’t know how durable the artificial discs will be in the long run, says Dr. Scott Boden, director of the Emory Spine Center at Emory University School of Medicine in Atlanta. And whether they will replace spinal fusion remains to be seen.
“Spinal fusion is one of the better procedures we do,” says Boden. “So anything that is going to try to replace that has a tall task in front of it.”
Nockels cautions that people in need of an immediate solution for cervical disc pain should not wait for an artificial disc, which could still be several years from reaching the market.
But he adds, “We’re all living longer, and the operation of fusion in the neck is 30 years old. With spinal [problems] being so prevalent, we need to improve our surgical treatment.”
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Now being tested: a lower-back disc
An artificial disc is also being tested for problems in the lower back, called the lumbar spine.
One experimental device, called the SB Charite Artificial Disc, has been tested in the United States in recent years and is now being evaluated by the Food and Drug Administration for possible market approval.
The disc is available in many other countries, and it could become the first lumbar artificial disc available in the United States.
At least three other companies are working on similar products.
All the artificial discs for the spine aim to preserve motion, says Dr. Russ P. Nockels of Loyola University Chicago Stritch School of Medicine. Artificial discs in the lower back, however, are larger.
