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.