Method and system for aligning a prosthesis during surgery

A computer implemented method to guide surgery comprising:

• receiving, at a processor, sensor information from a first sensor unit attached to a first bone of a patient, the first sensor unit generating and communicating the sensor information with which to determine a relative position in six degrees of freedom of an object with respect to the first bone, the sensor information generated in response to a signal from a second sensor unit attached to the object and wherein:
• the first sensor unit comprises an optical sensor;
• the second sensor comprises at least three markers configured to emit or reflect light to provide the signal representing the position of the object;
• and, the object comprises a surgical tool or a second bone of the patient;
• determining, by the processor, the relative position in six degrees of freedom in accordance with the sensor information;
• receiving, by the processor, input from at least one human interface sensor to invoke the processor to save the relative position, wherein either the first sensor unit or the second sensor unit comprises the at least one human interface sensor;
• determining a second relative position in six degrees of freedom in accordance with second sensor information received from the first sensor unit:
• determining, by the processor, display information in accordance with a comparison of the relative position as saved and the second relative position;
• and,
• providing, by the processor, the display information for presenting by a display unit.

A system for intra-operative surgical measurement and display of the relative position of a surgical tool with respect to a pelvis of a patient in total hip arthroplasty (THA) surgery, the system comprising:

• at least one human interface sensor to receive user input;
• and an optical sensor comprising a camera, the at least one human interface sensor and optical sensor which, when in use, are attached to the pelvis to position a field of view of the optical sensor in alignment with a surgical site for the THA;
• a sensor unit which, when in use, is attached to the surgical tool, the sensor unit comprising at least three markers configured to emit or reflect light to provide a signal representing a six degrees of freedom position for receiving by the optical sensor, the optical sensor generating and communicating sensor information in response to the signal with which to determine position in six degrees of freedom;
• and
• a processor configured to:
• receive the sensor information from the optical sensor;
• determine the relative position in six degrees of freedom in accordance with the sensor information;
• receive the input signal from the at least one human interface sensor to invoke the processor to save the relative position;
• determine a second relative position in six degrees of freedom in accordance with second sensor information received from the first sensor unit;
• determine display information in accordance with a comparison of the relative position as saved and the second relative position;
• and,
• provide the display information for presentation by a display unit.