Patent ID: 7708779

Claim:
An intervertebral spacer comprising: first and second members having respective contact surfaces to contact adjacent vertebral bodies, said first and second members being movable with respect to one another between a retracted position and an extended position, one of said first and second members being a plate; said first and second members configured to engage an insertion tool when said first and second members are in a retracted position, and to release said tool when said first and second members are moved to an extended position; and a jack mechanism to move said first and second members between said retracted and extended positions, said jack mechanism including a threaded shaft that extends outward from one of the first and second members and terminates at a distal end, a ring gear with a threaded opening that receives the threaded shaft, the distal end of said threaded shaft remains within said ring gear when said spacer is in the retracted position; the ring gear further including outwardly-extending gear teeth that extend radially outward from an exterior surface, and a drive gear with a helical extension that engages with the gear teeth, said jack mechanism configured for rotation of the drive gear in a first direction moving the first and second members towards the retracted position and rotation in a second direction moving the first and second members towards the extended position; each of said first and second members includes a tool-engaging element to capture a head of an insertion tool by moving said first and second members from an extended position to the retracted position.