As a treatment for spinal-disc degeneration, replacement with an artificial disc has emerged as an intriguing alternative to spinal fusion, in which the bad disc is taken out and the two surrounding vertebrae are fused together. The idea is to eliminate pain while avoiding some of the disadvantages of fusion, such as decrease in range of motion. The U.S. market for the discs reached $55 million in 2007, according to a 2008 report by Life Science Intelligence. The firm expects the number to reach $440 million by 2013. Growth, so far, has been limited by several disadvantages.
Wear
Different materials and designs have been used for artificial discs. The Charite Artificial Disc, made by DePuy Spine of Raynham, Massachusetts, and approved by the U.S. Food and Drug Administration (FDA) since 2004, is composed of cobalt chromium polyethylene. The discs have to last for many years or decades, especially since candidates for artificial disc surgery are often are between ages 30 and 50. It is possible that the artificial disc will wear out and need to be replaced. Such a procedure can be complicated and dangerous. The surgeon must avoid the vascular structures that lie near the disc, as well as any scar tissue left by the original surgery. Research has not yet conclusively shown how long the discs last, though they have shown only minimal wear after 10 years, orthopedic surgeons Jeffrey Goldstein and Mark Mikles have written for Spine-Health.
Surgical Complications
Having an artificial spinal disc implanted is a major surgical procedure, and complications are possible, though rare. Among them are blood loss, infection and injury to nerves, with potential for paralysis. These complications are similar to those associated with spinal fusion. But replacement with an artificial disc carries other potential complications, including breakage and dislocation of the implant, requiring further surgery. Selection of appropriate patients and implant size can help to avoid these complications. Patients with only one faulty disc and who do not have bones weakened from aging or disorders are the best candidates. In 2003, researchers M. de Kleuver, F. Oner and W. Jacobs, writing in the "European Spine Journal," looked at nearly 15 years of data from several studies and found a complication rate of as high as 50 percent.
Failure
Artificial disc replacement does not always succeed in its goal of reducing or eliminating back pain. In these cases, the patient ends up undergoing and recovering from an involved procedure and receiving no benefit. This is the same problem encountered with spinal fusion, for which the success rate is only 75 to 80 percent, according to Dr. Richard P. Emmanuel of Southern California Orthopedic & Musculoskeletal Associates. In a study published in 2006 in the "Journal of Bone and Joint Surgery," a group of researchers studying 304 patients at 14 centers in the United States found that replacement with the Charite disc was at least as effective as fusion.
