An adaptable spinal facet joint prosthesis, including a pedicle fixation element; a laminar fixation element; and a facet joint bearing surface having a location adaptable with respect at least one of the pedicle fixation element and the laminar fixation element. The invention also includes a method of implanting an adaptable spinal facet joint prosthesis including the steps of determining a desired position for a facet joint bearing surface; and attaching a prosthesis comprising a facet joint bearing surface to a pedicle portion of a vertebra and a lamina portion of a vertebra to place the facet joint bearing surface in the desired position. The invention also provides a facet joint prosthesis implant tool including a tool guide adapted to guide a vertebra cutting tool; and first and second fixation hole alignment elements extending from the saw guide.