Patent ID: 8715349

Claim:
An intervertebral spacer device comprising: a first plate having an inner surface, an outer surface, a central region and a peripheral region surrounding the central region; a second plate having an inner surface confronting the inner surface of said first plate, an outer surface facing away from said second plate, a central region and a peripheral region surrounding the central region; a ball projecting from the inner surface of said second plate and extending toward the inner surface of said first plate; a coupling element for coupling said first and second plates together, said coupling element having a central opening for receiving the ball projecting from said second plate, said coupling element having a convex surface facing the inner surface of said second plate and a concave surface facing the inner surface of said first plate, wherein the concave surface adjacent the central opening of said coupling element is spaced from the inner surface of said first plate; and a retaining wall extending from the inner surface of said first plate, said retaining wall surrounding said coupling element, wherein a retaining ring overlying the central region of said first plate and spaced inwardly from the peripheral region of said first plate is engaged with and lies within said retaining wall and further lies circumferentially adjacent to the convex surface of the coupling element; wherein said coupling element is maintained against said first plate by said retaining ring.