A method for guiding a bone removal device to form an implantation space in the human spine and, if desired, for inserting a spinal implant having at least in part non-arcuate upper and lower portions into the implantation space is disclosed. The method includes the act of positioning a guard into a disc space between adjacent vertebral bodies. The guard has a body and a disc space penetrating extension for insertion at least in part into the disc space and for bearing against the adjacent vertebral bodies. A first portion and a second portion of the guard are rotatable articulatable relative to one another. The method further includes the acts of rotatably articulating the guard to move the body from an open position to a closed position and move the extension from an insertion position to a deployed position. In doing so, the adjacent vertebral bodies are moved apart, and an implantation space is formed through the guard.