Patent ID: 7780731

Claim:
An intervertebral device for insertion between two adjacent vertebrae, comprising: an upper part having an upper surface for engaging an upper vertebrae and a lower surface having a convex portion; a lower part having a lower surface for engaging an adjacent, lower vertebrae and an upper surface having a convex portion; and a core element having an upper concave portion to operatively engage with said convex portion of said upper part and a lower concave portion to operatively engage with said convex portion of said lower part, wherein the upper and lower parts each have a groove located adjacent to and surrounding their respective convex portions, the groove having a groove floor surface adjacent the convex portion and a groove side wall surface located radially more distant from the convex portion than the groove floor surface and that extends from the groove floor surface toward the opposing part, wherein the core element comprises an upper surface surrounding the upper concave portion, the upper surface terminating in a circumferential surface, and further comprises a lower surface surrounding the lower concave portion, the lower surface terminating in a circumferential surface, and wherein the groove side wall surface of the upper and lower parts is constructed such that upon bringing the upper and lower parts together at an edge of the intervertebral device the terminal circumferential surface of the core element engages the groove side wall surface.