Computer-assisted joint replacement surgery and navigation systems

A computer-readable storage medium for performing a hip replacement surgery, comprising:

• instructions executable by at least one processing device that, when executed, cause the processing device to
• (a) measure a pre-dislocation positional relationship between a femur sensor unit coupled to the patient's femur and a pelvis sensor unit coupled to the patient's pelvis,
• (b) perform a post-dislocation anatomical registration of the femur to define a femoral coordinate system by measuring, in a single registration measurement, an orientation in three degrees of freedom between the femur sensor unit and a broach sensor unit coupled to a broach inserted within the patient's femur such that positional axes of the broach are collinear or parallel to positional axes of the femur and the coordinate system of the broach matches the coordinate system of the femur,
• (c) measure a reduction orientation between the femur sensor unit and the pelvis sensor unit during a reduction procedure, and
• (d) calculate a change in leg length and a change in offset, based on the pre-dislocation positional relationship, the reduction orientation and the anatomical registration of the femur.

A computer-readable storage medium for performing a hip replacement surgery, comprising:

• instructions executable by at least one processing device that, when executed, cause the processing device to
• (a) measure a pre-dislocation translational position and orientation between a pelvis sensor unit coupled to a patient's pelvis and a femur sensor unit coupled to the patient's femur,
• (b) perform an anatomical registration of the femur to define a femoral coordinate system by measuring, in a single registration measurement, an orientation in three degrees of freedom between a femur sensor unit coupled to the femur and a broach sensor unit coupled to a broach inserted within the patient's femur after the femur has been dislocated from the pelvis such that positional axes of the broach are collinear or parallel to positional axes of the femur and the coordinate system of the broach matches the coordinate system of the femur,
• (c) display a graphic mapping the pre-dislocation orientation against a real-time orientation between the pelvis sensor unit and the femur sensor unit, during a reduction procedure, and
• (d) calculate a change in leg length and a change in offset, after the reduction procedure, based on the pre-dislocation translational position, a post-reduction translational distance between the femur sensor unit and pelvis sensor unit and the femoral coordinate system.

A computer-readable storage medium for performing a hip replacement surgery, comprising:

• instructions executable by at least one processing device that, when executed, cause the processing device to
• (a) measure a pre-dislocation leg length and offset between a patient's pelvis and a patient's femur using data obtained from any one of (1) a preoperative scan of the patient's pelvis and the patient's femur and (2) respective sensor units coupled to the patient's pelvis and the patient's femur,
• (b) perform an anatomical registration of the femur to define a femoral coordinate system by measuring, in a single registration measurement, an orientation in three degrees of freedom between a femur sensor unit coupled to the femur and a broach sensor unit coupled to a broach inserted within the patient's femur after the femur has been dislocated from the pelvis such that positional axes of the broach are collinear or parallel to positional axes of the femur and a coordinate system of the broach matches a coordinate system of the femur,
• (c) track a position of the femur relative to the pelvis during a reduction procedure, and
• (d) calculate a change in leg length and a change in offset, after the reduction procedure, based on the femoral coordinate system and the pre-dislocation leg length and offset measurement.