"Those who received the artificial disc either did equally as well or a little bit better than those who had fusion surgery," said K. Daniel Riew, a cervical spine surgeon at Washington University Orthopedics and Barnes-Jewish Hospital. "One of the most important findings was that people who got the artificial disc were able to preserve all of their motion."
Spinal discs function as shock absorbers between the vertebrae of the spine. When a disc ruptures (herniates), the viscous tissue inside can enter the spinal canal and irritate nerves, causing numbness, weakness or pain. The most widespread solution has been to remove the spent disc and fuse the spinal bones together, using rods, screws and bone grafts, which requires a considerable postsurgical healing process. It also somewhat restricts the neck’s motion once healing has taken place.
In the study, 463 patients were randomly assigned to get either an artificial disc replacement (242 patients) or a spinal fusion (221). Two years following their surgery, the patients were measured with a tool known as the neck disability index (NDI). Both groups experienced less numbness and neck and arm pain.
Taking everything into account, the surgery was deemed successful for 83 percent of those who received artificial discs and 73 percent of patients who had fusion surgery. Riew said part of the reason for the difference is that the artificial disc patients had better range of motion in their neck.
“Fusion adds a small amount of stress in the spine above and below the fusion site, so bone can break down a little faster than normal,” he explained. “If the patient is a young person, then they may need another operation in 20 or 30 years. The hope with artificial cervical disc replacement is the preserved motion may protect against additional stress at other levels of the spine.”