LEG ALIGNMENT FOR SURGICAL PARAMETER MEASUREMENT IN HIP REPLACEMENT SURGERY

摘要

A CAS system (50) and method (100) for measuring surgical parameters during hip replacement surgery to guide an operator (S) in inserting a hip joint implant in a femur, comprising a first trackable reference (56) in fixed relation with the pelvis and a registration tool (56). A sensor apparatus (54) tracks the first trackable reference (56) and the registration tool (56). A controller unit (52) is connected to the sensor apparatus (54) so as to receive tracking data for the first trackable reference (56) and the registration tool (56). The controller unit (52) has a position and orientation calculator (202) to calculate from the tracking data a position and orientation of the pelvic trackable reference (56) to track the pelvic frame of reference, and of the registration tool (56) to produce a femoral frame of reference at two sequential operative steps. A reference orientation adjustor (204) receives tracking data for the pelvic frame of reference, and the femoral frame of reference associated with the first trackable reference (56), 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 (206) receives tracking data from the registration tool (56) to calculate surgical parameters as a function of the reference adjustment value, the surgical parameters at the two sequential operative steps being related by the reference orientation.