That number has increased since the Charite artificial spinal disc was approved for use in the US in October 2004. As of July 2006, there have been more than 130 serious adverse events reported to the FDA associated with its use.
Examples of the serious adverse events include: migration of the artificial disc resulting in either removal of the disc or maintaining the disc, both followed by fusion; pedicle fractures; subsidence or a settling of the disc into the bone; and nicking of an vein or artery.
Professor Karin Buttner-Janz and Professor Kurt Schellnack, considered to be leading spine specialists, originally developed the Charite disc at the Charite University Hospital in Berlin, Germany in the mid-1980s. Further refinements to the design were later incorporated at Waldemar Link GmbH, a European based medical device maker.
According to Spine Health.com, the Charite is approved for patients who have severe lower back pain and have obtained little or no pain relief after at least 6 months of non-surgical treatments, such as pain medications, physical therapy, injections, or manipulation. "The FDA clearance for disc replacement," the site says, "is for one level of the lower spine, and it must be done at one of the two lowest levels of the spine (L4-L5 or L5-S1)."
The device was approved to relieve pain by replacing the damaged disc with the Chirate disc, as an alternative to the surgical procedure known as lumbar spinal fusion surgery
When done correctly for the right indications, experts say, a fusion has a high success rate in relieving pain. However, because it limits the range of motion, extra stress may transfer to the discs above and below the fusion site.
An artificial disc is supposed to allow continued motion in the spinal segment, and therefore, the Charite was thought to be a viable alternative to spinal fusion surgery for patients with the right indications.
However, in the paper, "Total Disc Replacement for Chronic Low Back Pain: Background and a Systematic Review of the Literature," by M de Kleuver, F Oner, W Jacobs in the European Spine Journal Volume 12, Number 2, April 2003, the authors determined that despite the fact that these devices have been implanted for almost 15 years, on the basis of this literature survey there are currently insufficient data to assess the performance of total disc replacement adequately.
There is no evidence, the paper said, that disc replacement reliably, reproducibly, and over longer periods of time fulfils the three primary aims of clinical efficacy, continued motion, and few adjacent segment degenerative problems.
Total disc replacement, they said, seems to be associated with a high rate of re-operations, and the potential problems that may occur with longer follow-up have not been addressed.
J&J beat out competitors Stryker and Medtronic by securing approval of the Charite, but many surgeons have criticized the FDA for approving the device and ignoring over 17 years of evidence related to its use Europe, including a study showing that more than half of recipients had fair or poor results.
The FDA approved the Chirate based on the results of a single two-year clinical trial, that was designed to merely establish that the Charite disc worked at least as well as the Bagby and Kuslich cages (BAK) used in spinal fusions.