The invention includes: a locating system; a computer, interfaced to the
locating system and interpreting the positions of tracked objects in a
generic computer model of a patient's hip geometry; a software module,
executable on the computer, which defines the patient's pelvic plane
without reference to previously obtained radiological data, by locating at
least three pelvic landmarks; and a pelvic tracking marker, fixable to the
pelvic bone and trackable by the locating system, to track in real time
the orientation of the defined pelvic plane. Preferably, the system also
includes a femoral tracking marker, securely attachable to a femur of the
patient by a non-penetrating ligature and trackable by the locating system
to detect changes in leg length and femoral offset.
