A measurement tool is designed to measure the relative displacements between two bony landmarks of a spine, such as pedicles and facet surfaces. The measurement tool may have a registration interface designed to be registered to a first bony landmark, and a contact feature shaped to contact a second bony landmark. The registration interface may be registered to a frame rigidly coupled relative to the first bony landmark. The measurement tool also has a displacement structure that permits motion of the contact feature relative to the registration interface along multiple dimensions. The displacement structure may have two or three sliding joints that enable relative translation along orthogonal axes. Each sliding joint may have a rod with a plurality of markings that can easily be read to acquire measurements from the displacement structure.