The Bionic Back

A Sturdy Backup Each Charit disc consists of a sliding polyethylene core sandwiched between two plates made of durable cobalt-chromium alloy. Depuy Spine

For some of the 200,000 people each year who suffer pain severe enough to require lower-back surgery, a new solution has arrived. The Charit Artificial Disc is expected to receive FDA approval for degenerative disc disease by the end of 2004, making it the only artificial spinal disc available in the U.S. “This is the first major breakthrough in back surgery since the 1940s,” says orthopedic surgeon Richard Guyer of the Texas Back Institute in Plano.


The Charit replaces one of two lower-back discs, which help cushion the spine, enable the back to bend, and keep the nerves that exit the spinal column from being pinched by bone. In a procedure that takes as little as an hour, a surgeon cuts into the patient’s abdomen, clears a path to the spine, scrapes out the damaged disc, and inserts the Charit. Whereas fusion surgery immobilizes the joints by fastening two vertebral bones together, the Charit promises a more natural range of motion. At the heart of the prosthesis is a low-friction
polyethylene plastic—the same materials proven effective in artificial hips and knees—that allows for flexibility through a modified ball-and-socket action.


To anchor the bone in place, six teeth on each endplate sink about three millimeters into
the bone. It sounds painful, but patients can’t feel it, and in many cases, their back trouble disappears within days. A
similar spine implant, called ProDisc, is now in clinical testing and could receive FDA approval within the next year.