An artificial disc having a pair of opposing baseplates, for seating against opposing vertebral bone surfaces, separated by a ball and socket joint that includes a solid ball mounted to protrude from one of the baseplates. The ball is captured within a curvate socket formed in a peak of a convex structure...http://www.google.de/patents/US20030074068?utm_source=gb-gplus-sharePatent US20030074068 - Artificial intervertebral disc having limited rotation using a captured ball and socket joint with a solid ball and retaining cap
