Patent ID: 8506634

Claim:
An intervertebral implant that is configured to be retained within an intervertebral disc space between adjacent first and second vertebrae, comprising: a first part having a first outer surface adapted for engaging the first vertebra, a first inner surface opposing and facing away from the first outer surface having a concave indentation, and a first sidewall located between the first outer and inner surfaces extending around the circumference of the first part; a second part having a second outer surface adapted for engaging the second vertebra, a second inner surface opposing and facing away from the second outer surface having a convex protrusion portion adapted to engage the indentation of the first part, and a second sidewall located between the second outer and inner surfaces extending around the circumference of the second part, wherein on the second inner surface, located between the convex portion and the second sidewall and located radially outward of the convex portion, there is a portion not adapted to engage the indentation of the first part; wherein at least one of the first part concave indentation and the second part convex portion is a spherical surface; wherein the first part and the second part each have a leading end and a trailing end opposite the leading end, and opposing lateral sides between the leading end and the trailing end; wherein the first and second parts each have an elongated anchor that is elongated in a lengthwise direction from the trailing end to the leading end and having a height greater than its width on their respective first and second outer surfaces, and extending outwardly from the respective outer surfaces, each elongated anchor being located essentially along the center of the respective first and second outer surfaces between the lateral sides, the first and second part anchors being adapted to anchor the respective part in the respective vertebra; and wherein the first and second parts can be engaged in an insertion position with the respective leading ends forward and the lateral sides of the first part generally parallel with the lateral sides of the second part such that the elongated anchors lie in essentially the same vertical plane and wherein the first and second parts are adapted such that in the insertion position with the elongated anchors vertically oriented in the direction of the respective anchor height, the first sidewall is located in a different horizontal plane than the second sidewall.