A method comprises providing a current state image and at least one reference image, taken from a similar angle range. The image and the at least one reference image are superimposed and a visual representation visualizing the relation between the image and the reference image is provided in order to track displacements of the bone during subsequent operation steps. A system is provided which can use the image data to track displacements and determine deviation from a current state of the elements in question to a target state.