The described method for determining at least orientation of a pelvic bone in space and for tracking movement of the pelvic bone using a computer assisted surgery (CAS) system includes removably attaching, in a non-invasive manner, at least one reference marker, in communication with the CAS system, to a skin surface covering the pelvic bone. Registering at least orientation readings of the reference marker is then performed with respect to a fixed reference in a reference coordinate system, following which at least an orientation of the pelvic bone in the reference coordinate system is determined using the orientation readings of the reference marker. These steps are repeated to update the orientation readings while tracking the pelvic bone in space.
