Orthopedic implant and methods of implantation for fixing adjacent bones. In one embodiment, the implant includes a locking mechanism that is adapted to be advanced by a locking instrument, wherein advancement of the locking mechanism in a first direction produces rotation of a first rigid abutment surface of the implant from a first orientation to a second orientation, and continued advancement of the locking mechanism produces advancement of the first rigid abutment surface towards a second rigid abutment surface of the implant. The continued advancement may also place a compressive load onto the implant sufficient to immobilize the implant relative to a first bony surface and a second bony surface.
