an expandable interspinous process fixation system capable of restoring spinal stability and facilitating fusion . in one embodiment , the expandable interspinous process fixation system includes a central ramp , a first endplate , and a second endplate , the central ramp capable of being moved in a first direction to move the first and second endplates outwardly and into an expanded configuration . each endplate supporting fixed and / or adjustable spinous process engaging plates .