A pair of bone plates adapted for attachment to cranial bone segments, the cranial plates being mounted to a distraction mechanism such that the cranial plates can be separated gradually in very small increments. Each of the cranial plates is mounted to the distraction mechanism with a ball and socket connector assembly, such that each of the plates can move in multiple directions and orientations relative to the distraction mechanism to better accommodate a convex, planar or concave surface topography presented during the distraction procedure.