A spacer for separating bones of a joint, the spacer includes a first endplate configured to engage a first bone of the joint； a second endplate configured to engage a second bone of the joint； tissue engaging projections, wherein the tissue engaging projections are moveable from a retracted position to a deployed position； and an actuation subassembly that extends between the first endplate and the second endplate, wherein the actuation subassembly comprise a drive nut, a drive screw coupled to the drive nut, and a cam frame coupled to the drive screw, wherein the cam frame is disposed between the first endplate and the second endplate to engage the tissue engaging projections.
