An implant for therapeutically separating bones of a joint, the implant defining a longitudinal axis extending between distal and proximal ends, the implant comprising: a first endplate configured to engage a first bone of the joint, and having an opening through the endplate, and at least one ramped surface on a side opposite a bone engaging side; a second endplate configured to engage a second bone of the joint, and having an opening through the endplate, and at least one ramped surface on a side opposite a bone engaging side, wherein at least one of the first and second endplates includes at least one aperture through which a fastener may pass to secure the implant to bone of the joint, a frame slideably connected to the first and second endplates to enable the first and second endplates to move relative to each other at an angle with respect to the longitudinal axis, in sliding connection with the frame; an actuator screw rotatably connected to the frame; and a carriage having an open area defining a proximal carriage side and a distal carriage side with respect to the longitudinal axis, and connected to the actuator screw, whereby rotation of the actuator screw moves the carriage with respect to the frame and the first and second endplates, the actuator screw not crossing between the proximal carriage side and the distal carriage side; and wherein the carriage comprises a plurality of ramps (168, 168A) each mateable with at least one of the at least one ramped surfaces (164, 164A) of the first and second endplates, wherein when the carriage is moved by rotation of the actuator screw, at least one of the at least one ramped surface of the first endplate and at least one of the at least one ramped surface of the second endplate each move along at least one of the plurality of ramps (168, 168A) of the carriage to cause the endplates (110, 112) to move relative to each other in connection with the frame; characterized in that the open area of the carriage is aligned with the openings in the first and second endplates; and the first endplate forms an upper portion of the aperture and the second endplate forms a lower portion of the aperture. a first endplate configured to engage a first bone of the joint, and having an opening through the endplate, and at least one ramped surface on a side opposite a bone engaging side; a second endplate configured to engage a second bone of the joint, and having an opening through the endplate, and at least one ramped surface on a side opposite a bone engaging side, wherein at least one of the first and second endplates includes at least one aperture through which a fastener may pass to secure the implant to bone of the joint, a frame slideably connected to the first and second endplates to enable the first and second endplates to move relative to each other at an angle with respect to the longitudinal axis, in sliding connection with the frame; an actuator screw rotatably connected to the frame; and a carriage having an open area defining a proximal carriage side and a distal carriage side with respect to the longitudinal axis, and connected to the actuator screw, whereby rotation of the actuator screw moves the carriage with respect to the frame and the first and second endplates, the actuator screw not crossing between the proximal carriage side and the distal carriage side; and wherein the carriage comprises a plurality of ramps (168, 168A) each mateable with at least one of the at least one ramped surfaces (164, 164A) of the first and second endplates, wherein when the carriage is moved by rotation of the actuator screw, at least one of the at least one ramped surface of the first endplate and at least one of the at least one ramped surface of the second endplate each move along at least one of the plurality of ramps (168, 168A) of the carriage to cause the endplates (110, 112) to move relative to each other in connection with the frame; characterized in that the open area of the carriage is aligned with the openings in the first and second endplates; and the first endplate forms an upper portion of the aperture and the second endplate forms a lower portion of the aperture.