Abstract: A tracking system is provided for tracking objects. A first and a second trackable member each have an inertial sensor unit producing at least orientation-based data. A processing unit receives the orientation-based data from the trackable members. The processing unit has an orientation calculator calculating an orientation of the second trackable member with respect to the first trackable member from the orientation-based data of the trackable members, whereby the processing unit calculates an orientation of the objects. A method for tracking objects is also provided.

Abstract: A method for assisting in positioning the acetabular cup comprises orienting a cup positioning instrument with a cup thereon in an initial reference orientation relative to an acetabulum of a pelvis with the cup forming a joint with the acetabulum, the cup positioning instrument comprising an inertial sensor unit with pre-planned orientation data for a desired cup orientation based on at least one landmark of the pelvis, The cup positioning instrument is rotated to a desired abduction angle as guided by an interface of the cup positioning instrument, based on movements relative to at least one landmark. The cup positioning instrument is rotated to a desired anteversion angle as guided by the interface of the cup positioning instrument, based on movements relative to the at least one landmark. Upon reaching the desired cup orientation as indicated by the interface, the cup is impacted into the acetabulum.

Abstract: A tracking system is provided for tracking objects. A first and a second trackable member each have an inertial sensor unit producing at least orientation-based data. A processing unit receives the orientation-based data from the trackable members. The processing unit has an orientation calculator calculating an orientation of the second trackable member with respect to the first trackable member from the orientation-based data of the trackable members, whereby the processing unit calculates an orientation of the objects. A method for tracking objects is also provided.

Abstract: A system for tracking a femoral frame of reference in computer-assisted surgery comprises a sensor unit. The sensor unit is adapted to be secured to the femur. The sensor unit comprises accelerometer and gyroscope sensors that produce orientation data. A processing unit receives gyroscope and accelerometer data. The processing unit comprises a gyroscope-data calculator to provide calculated acceleration data resulting from movements of the femur, an accelerometer-data calculator to calculate measured acceleration data resulting from movements of the femur, and an acceleration comparator to relate an orientation of the sensor unit to the femur to define a femoral frame of reference. The femoral frame of reference is defined from the comparison between the calculated and the measured acceleration data. A sensor orientation interface provides orientation data for the femur from a tracking of the femoral frame of reference. A method for tracking a femoral frame of reference is also provided.

Abstract: A calibration system for the calibration of a surgical instrument, comprises a surgical instrument having a working shaft. A clamp has a first trackable member and is releasably connected to the surgical instrument such that an orientation relation between the clamp and the working shaft of the instrument is known. A base is separated from the clamp and has a second trackable member and a positioning portion being tracked for position. A sensor unit tracks the first and second trackable members. A calibration unit calibrates the surgical instrument by initializing the orientation relation between the clamp and the working shaft from the tracking data to obtain an orientation of the working shaft, and by setting a position for the working shaft with respect to the first trackable member by relating the orientation of the working shaft to the position of the positioning portion when the working shaft contacts the positioning portion.

Abstract: A CAS system for measuring surgical parameters during hip replacement surgery comprises a first tracking reference in fixed relation with the pelvis to form a frame of reference. A registration tool is trackable. A sensor apparatus tracks the first tracking reference and the registration tool. A controller unit receives tracking data for the first trackable reference and the registration tool. The controller unit has a position and orientation calculator for calculating from the tracking data a position and orientation of the pelvic tracking reference to track the frame of reference, and of the registration tool to produce femoral models at a first and a second sequential operative steps. An alignment adjustor aligns the femoral models with the frame of reference. A surgical parameter calculator calculates surgical parameters as a function of the femoral models as aligned by the alignment adjustor.

Abstract: A method for establishing an interaction between an operator and a monitor of a computer-assisted surgery system comprises tracking a tool manipulated by the operator for providing surgical data calculated from the position/orientation of the tool. A desired interaction is identified from the operator by tracking the tool reaching a specific position and/or a specific orientation. An interactive action is activated on a monitor as a function of the desired interaction, the interactive action being unrelated to said surgical data. A motion of the tool is converted to additional interactions related to said interactive action. A computer-assisted surgery system is also provided.

Abstract: A method of determining a center of curvature of the spherical outer surface of an object using a computer system is provided. The method includes defining at least one contact region on the spherical outer surface in a plane substantially tangential to a circumference thereof and a first reference axis normal to said plane. Spatial coordinates of at least one of a first and a second geometric parameter are determined, the first geometric parameter including at least two points located on the spherical outer surface and the second geometric parameter including a second reference axis normal to the spherical outer surface. The center of curvature of the spherical outer surface is then calculated using the first reference axis and at least one of the first and second geometric parameters. An associated system and calibration device is also provided.

Abstract: A method of determining a center of curvature of the spherical outer surface of an object using a computer system is provided. The method includes defining at least one contact region on the spherical outer surface in a plane substantially tangential to a circumference thereof and a first reference axis normal to said plane. Spatial coordinates of at least one of a first and a second geometric parameter are determined, the first geometric parameter including at least two points located on the spherical outer surface and the second geometric parameter including a second reference axis normal to the spherical outer surface. The center of curvature of the spherical outer surface is then calculated using the first reference axis and at least one of the first and second geometric parameters. An associated system and calibration device is also provided.

Abstract: A hip resurfacing CAS system for guiding an operator in altering a femoral head in computer-assisted surgery for subsequent implanting of a femoral head implant, comprises a trackable reference on the femur. A registration tool is trackable. A bone-altering tool is associated with a resurfacing of the femoral head. A tracking apparatus tracks the tools. A resurfacing processing unit is connected to the tracking apparatus so as to receive tracking data for the tools. The resurfacing processing unit has a position/orientation calculator to calculate from the tracking data a position and orientation of the trackable reference to track the femoral frame of reference, and of the registration tool and the bone-altering tool. A model generator receives position and orientation data of the registration tool to produce a model of the femoral head and neck with respect to the femoral frame of reference.