A monitoring system tracks the non-visible structure of a body and relatable non-visible structures in real time in three dimensions. A tracker obtains image information of the body and its vicinity. A controller spatially relates the image information with previously obtained scan data of the object revealing non-visible structure of the object. For the scan, a fiducial reference detectable in the scan is removably attached to a location on the object. The scan data and image information are used by the controller to provide the user with real time information about the relative 3D locations and orientations of the relatable non-visible structures and the non-visible structure of the body. Using three-dimensional tracking markers attached to the fiducial reference on the body and to the relatable non-visible structures, the system and method may be employed to track in three dimensions in real time a plurality of bodies having non-visible structure. Three-dimensional tracking markers intergrated with surgical screws may be attached directly to the relatable non-visible structures.
