Pelvic digitizer device with inertial sensor unit and method

An assembly of a pelvic digitizer device and pelvic tracker device comprising:

• the pelvic digitizer device comprising:
• a body comprising:
• a shaft having a tooling end and a handle end with a handle for being manipulated,
• a visual guide oriented in a reference plane of the digitizer device, and
• a cup connected to the tooling end and adapted to be received in an acetabulum of a patient;
• and
• an inertial sensor unit connected to the body, the inertial sensor unit having a preset orientation for calibration of the pelvic digitizer device relative to a pelvis of a patient, the preset orientation being based on pre-operative imaging specific to the pelvis of the patient, the preset orientation being aligned with the reference plane;
• and
• the pelvic tracker device comprising:
• a tracker body adapted to be fixed to a pelvis of the patient,
• another inertial sensor unit with a preset orientation for calibration of the pelvic tracker device, the preset orientation being based on the pre-operative imaging specific to the pelvis of the patient,
• a three DOF rotational joint between the inertial sensor unit and the body, and
• a visual guide displaceable with the inertial sensor unit for alignment with the reference plane of the pelvic digitizer device.

A method for creating at least part of a pelvic coordinate system of a patient in strict lateral decubitus, comprising:

• obtaining a pelvic digitizer device with an inertial sensor unit programmed with a preset orientation based on pre-operative imaging specific to a pelvis of a patient, the preset orientation being aligned with a reference plane of the pelvic digitizer device;
• inserting a cup of a pelvic digitizer device in a native acetabulum of the patient;
• visually aligning said reference plane of the pelvic digitizer device with a frontal plane of the patient, in a visual alignment;
• and
• in the visual alignment, initializing an inertial sensor unit of the pelvic digitizer device to set an orientation of the pelvic digitizer device relative to an anterior-posterior axis of the patient.