Artificial intervertebral disc having limited rotation using a captured ball and socket joint with a retaining cap and a solid ball having a protrusion

摘要

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 integral with the other baseplate. The socket is formed by opposing curvate pockets, one on the convex structure and one on a cap secured to the other baseplate. While the ball angulates in the socket, its rotation in the socket has a limited range due to interference between a protrusion on the ball that extends into a curvate recess, formed by the convex structure and the cap, adjacent the curvate socket. The ball and socket joint therefore permits the baseplates to rotate relative to one another through a limited range and also angulate relative to one another.