Abstract: A CAS system and method comprises a first reference in fixed relation with the pelvis and a registration tool. A sensor apparatus tracks the first reference and tool. A controller unit receives tracking data for the first reference and tool. A calculator tracks the pelvic frame of reference, and the tool to produce a femoral frame of reference at two sequential operative steps. A reference orientation adjustor receives tracking data for the pelvic frame of reference to orient the femoral frame of reference in a reference orientation with respect to the pelvic frame of reference, and to produce a reference adjustment value as a function of the reference orientation. A surgical parameter calculator receives tracking data from the tool to calculate surgical parameters as a function of the reference adjustment value.

Abstract: A CAS system and method for measuring surgical parameters during hip replacement surgery to guide an operator in inserting a hip joint implant in a femur, comprising a first trackable reference in fixed relation with the pelvis and a registration tool. A sensor apparatus tracks the first trackable reference and the registration tool. A controller unit is connected to the sensor apparatus so as to receive tracking data for the first trackable reference and the registration tool. The controller unit has a position and orientation calculator to calculate from the tracking data a position and orientation of the pelvic trackable reference to track the pelvic frame of reference, and of the registration tool to produce a femoral frame of reference at two sequential operative steps.