A method of representing a relative change in position and/or orientation of a bone portion during a surgical procedure according to some embodiments of the invention includes receiving preoperative x-ray computed tomography (CT) images of a bone that will have a portion separated and moved during the surgical procedure. Multiple x-ray images are received, each a different view of the bone during the surgical procedure prior to separating and moving the portion, where the bone has a fiducial marker fixed relative to that portion and another fiducial marker fixed relative to a stationary portion of the bone. The fiducial markers each have at least three radio-opaque points and remain substantially fixed with respect to each other. The position of the radio-opaque points is determined relative to a three-dimensional representation of the bone from the preoperative CT images. After separating and moving the portion, a single x-ray image is received that includes both fiducial markers. The relative change in position and/or orientation is estimated using the single x-ray image.