Artificial nucleus replacement: clinical experience.

The prosthetic disc nucleus is designed to help treat patients suffering from degenerative disc disease. The device consists of a hydrogel core that is encased in a polyethylene jacket and is intended to restore disc height while permitting normal range of motion. Clinical trials for the prosthetic disc nucleus were first conducted in 1996, and the device was found to be effective in most of the patients that were implanted. Additional trials in 1997-1998 were less successful, with 38% of patients requiring revision surgery because of device migration. Subsequent changes were made to device shapes and to the surgical protocol to facilitate implantation, thereby eliminating the high device migration rates. Following these modifications, the success rate for the device has improved significantly. Clinical data show excellent results with marked improvements in Oswestry and Prolo scores. Overall, disc height measurements have been well maintained within normal physiologic ranges. The prosthetic disc nucleus device is currently undergoing clinical trials in Canada, and an IDE application to the Food and Drug Administration was expected in the fall, 2001.