Abstract: A method for locating a guide wire axis on a femoral neck comprises the steps of tracking a position and orientation of a femur; registering a frame of reference with respect to the position and orientation of the femur from a first registration probe mounted onto the femur in a predetermined configuration, the frame of reference having preoperative planned data pertaining to the femoral neck; digitizing femoral neck data with respect to the position and orientation of the femur from a second registration probe positioned onto the femoral neck at desired orientations; calculating a position and orientation of the guide wire axis with respect to the position and orientation of the femur as a function of the preoperative planned data and the femoral neck data.

Abstract: A computer-assisted surgery system comprises instruments adapted to be used to perform tasks related to surgery. A reference device is in a fixed relation to a bone. A rotating magnet creates a magnetic field plane, the rotating magnet being connected to one of the instrument and the reference device. A magnetometer on the other of the instrument and the reference device produces signals as a function of at least its orientation relative to the magnetic field plane. A processing unit tracks said orientation of the instrument relative to the bone using said signals from the magnetometer subjected to the magnetic field plane.

Abstract: A method and system (10) for the installation of a cutting guide (60) on a bone element (33) in orthopedic computer assisted surgery is provided. The method includes positioning a drill guide (30) against a distal end of the bone element (33), determining at least two pin locations on one of a medial (31) and a lateral side of the bone element (33), fastening locating pins (42) to the bone element (33) at the determined pin locations, removing the drill guide (30) and installing a CAS bone reference (20) in its place on the same locating pins (42), and subsequently mounting the cutting guide (60) to the same locating pins (42).

Abstract: A computer-assisted surgery (CAS) navigation assembly comprises a micro-electromechanical sensor (MEMS) navigation unit having one or more MEMS to provide at least orientation data. A support receives the MEMS navigation unit therein, the support being adapted to be mounted on the instrument in a fixed orientation relative to established navigated features of the instrument. At least two mating ball-in-socket features are disposed between the MEMS navigation unit and the support at opposed ends thereof for releasably engaging the MEMS navigation unit in precise orientational alignment within the receptacle, the at least two mating ball-in-socket features comprising catches aligned along an axis extending between the opposed ends, at least one of the catches being a biased catch. A method of connecting a MEMS navigation unit with a mating support fixed to a CAS instrument navigated by the CAS system is also provided.

Abstract: A device (10,10?,20,20?) for digitizing a center of rotation of a hip joint implant component (A,F) with respect to a bone element in computer-assisted surgery. The device (10,10?,20,20?) comprises a detectable member (12,22) trackable for position and orientation by a computer-assisted surgery system (30). A body (11,21) is connected to the detectable member (12,22) in a known geometry. The body (11,21) has a coupling portion (14,14?,24,25) adapted to be coupled to the hip joint implant component (A,F) in a predetermined configuration. The center of rotation of the hip joint implant component (A,F) is calculable in the predetermined configuration as a function of the known geometry and of the position and orientation of the detectable member (12,22).

Abstract: A tracker device of the type is associated with a surgical instrument and being trackable in space by a CAS system such that a position of the surgical instrument is calculable. A support is adapted to be connected to the surgical instrument. Optical elements are mounted to the support in a first pattern so as to be detectable by the CAS system along a first range of visibility. Other optical elements are mounted to the support in a second pattern so as to be detectable by the CAS system along a second range of visibility, with the first range of visibility and the second range of visibility having at most a common portion, whereby a position of the surgical instrument is tracked within the first and the second range of visibility as a function of the detection of any one of the patterns of the optical elements.

Abstract: A positioning device assembly for positioning a tool guide block for use in an orthopedic surgery on a bone element includes a positioning device having a block body with a reference surface adapted to abut the bone element, and first and second adjustment mechanisms that are independently operable. The first adjustment mechanism permits rotation of a tool guide block about a medial-lateral extending axis such as to provide flexion-extension angle adjustment and the second adjustment mechanism permits rotation of a tool guide block about an anterior-posterior extending axis such as to provide varus-valgus angle adjustment. The second adjustment mechanism includes both a coarse and a fine adjustment mechanism integral therewith. A tool guide block assembly mounted to the positioning device, the tool guide block assembly including a platform portion which is engaged to the block body of the positioning device and the tool guide block which is releasably engaged with the platform.

Abstract: A computer-assisted surgery system for planning/guiding alterations to a bone in surgery, comprises a trackable member adapted to be secured to the bone. The trackable member has a first inertial sensor unit producing orientation-based data for at least two degrees of freedom in orientation of the trackable member A positioning block is adapted to be secured to the bone, with at least an orientation of the positioning block being adjustable once the positioning block is secured to the bone to reach a selected orientation at which the positioning block is used to guide tools in altering the bone. The positioning block has a second inertial sensor unit producing orientation-based data for at least two degrees of freedom in orientation of the positioning block. A processing system providing an orientation reference associating the bone to the trackable member comprises a signal interpreter for determining an orientation of the trackable member and of the positioning block from the orientation-based data.

Abstract: There is provided a method and system for determining a distal cut thickness and posterior cut thickness for a femur in a knee replacement operation, the method comprising: performing a tibial cut on a tibia; performing soft tissue balancing based on a desired limb alignment; measuring an extension gap between the femur and said tibial cut while in extension; measuring a flexion gap between the femur and the tibial cut while in flexion; calculating a distal cut thickness and a posterior cut thickness for the femur using the extension gap and the flexion gap and taking into account a distal thickness and posterior thickness of a femoral implant; and performing said femoral cut according to the distal cut thickness and posterior cut thickness.

Abstract: There is described a device for use with a position sensing system to register position and orientation in a reference-coordinate system, the device comprising a set of at least three base units removably and non-invasively attachable to a skin surface covering a bone, each of the base units having a reference marker attached thereto, the reference markers being one of passive and active devices recognized by the position sensing system and positioned and oriented in the reference coordinate system with respect to a fixed reference, the base units adapted to measure a distance between the skin surface and the bone in conjunction with an ultrasound component.

Abstract: A positioning block for use in knee surgery includes a rotational mounting removably engageable to the bone element by a multi-axial fastener such that the mounting element is selectively rotatable relative to the bone element about at least two substantially perpendicular axes of rotation. A guide body portion is engaged with the rotational mounting element such that it is translatable relative thereto along while being rotationally fixed relative to the mounting element. The guide body portion is moveable relative to the bone element in at least three degrees of freedom, the three degrees of freedom including at least two rotational degrees of freedom and at least one translational degree of freedom. A trackable member on the guide body portion is identified and tracked by a computer assisted surgery system.

Abstract: A method of determining a reference point on condyles of a femur uses a computer assisted surgery system having a digitizer with perpendicular first and second planar surfaces, the digitizer being locatable and trackable in three dimensional space by the computer assisted surgery system. A digitized plane is created using the digitizer, the digitized plane being a posterior plane and/or a distal plane of the condyles. The posterior plane and the distal plane are respectively defined by the first and second planar surfaces of the digitizer. A location of the reference point in the digitized plane is then determined using the computer assisted surgical system. The reference point is a most remote point of the femur within the digitized plane.

Abstract: A CAS system and method comprises a first reference in fixed relation with the pelvis and a registration tool. A sensor apparatus tracks the first reference and tool. A controller unit receives tracking data for the first reference and tool. A calculator tracks the pelvic frame of reference, and the tool to produce a femoral frame of reference at two sequential operative steps. A reference orientation adjustor receives tracking data for the pelvic frame of reference 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 receives tracking data from the tool to calculate surgical parameters as a function of the reference adjustment value.

Abstract: There is described a device for use with a position sensing system for tracking a bone in a reference coordinate system, the device comprising a fabric removably and non-invasively attachable to a bone and having a plurality of reference markers distributed thereon, the reference markers being one of passive and active devices recognized by the position sensing system and positioned and oriented in the reference coordinate system with respect to a fixed reference.

Abstract: A positioning block (10) for use in total knee replacement surgery, permitting five degrees-of-freedom movement relative to a bone element (39) to which it is fixed. The positioning block (10) comprises a rotational mounting element (14) that is removably engaged to the bone element such that the mounting element (14) is selectively rotatable relative to the bone element, about three substantially perpendicular axes of rotation. A guide body portion (12) is engaged with the mounting element (14) such that it is translatable relative thereto along a proximal-distal axis (43) and an anterior-posterior axis (47), while being rotationally fixed relative to the mounting element (14) such that the guide body portion (12) and the mounting element (14) rotate together relative to the bone element (39).

Abstract: A computer-assisted surgery system for guiding an operator in altering a pelvis. A sensing apparatus is provided for tracking a reference tool and a bone altering tool. A position calculator calculates a position and orientation of a pelvic frame of reference as a function of the tracking of the reference tool, and for calculating a position and orientation of the bone altering tool with respect to the frame of reference. A source of posture data and a posture data correction calculator are provided and are operative to provide a display of information allowing an operator to take into consideration the posture data from the source of posture data when altering the pelvis. A display unit is connected to the position calculator and to the posture data correction calculator for displaying the display of information and the bone altering tool with respect to the pelvic frame of reference.

Abstract: A positioning block (10) for use in total knee replacement surgery, permitting five degrees-of-freedom movement relative to a bone element (39) to which it is fixed. The positioning block (10) comprises a rotational mounting element (14) that is removably engaged to the bone element such that the mounting element (14) is selectively rotatable relative to the bone element, about three substantially perpendicular axes of rotation. A guide body portion (12) is engaged with the mounting element (14) such that it is translatable relative thereto along a proximal-distal axis (43) and an anterior-posterior axis (47), while being rotationally fixed relative to the mounting element (14) such that the guide body portion (12) and the mounting element (14) rotate together relative to the bone element (39).

Abstract: A method and system (10) for the installation of a cutting guide (60) on a bone element (33) in orthopedic computer assisted surgery is provided. The method includes positioning a drill guide (30) against a distal end of the bone element (33), determining at least two pin locations on one of a medial (31) and a lateral side of the bone element (33), fastening locating pins (42) to the bone element (33) at the determined pin locations, removing the drill guide (30) and installing a CAS bone reference (20) in its place on the same locating pins (42), and subsequently mounting the cutting guide (60) to the same locating pins (42).

Abstract: There present description is directed to a method and a system for determining a time delay between a transmission and a reception of an RF signal in a noisy environment. The method comprises: transmitting the RF signal according to a transmit frequency pattern, the transmit frequency pattern comprising at least three pulses separated by a period of time, each one of the at least three pulses respectively being at each one of at least three different frequencies; receiving a received RF signal comprising the at least three pulses at the at least three different frequencies, each one of the at least three different frequencies associated to a receive phase change; comparing the receive phase change of one of the at least three different frequencies with the receive phase change of another one of the at least three different frequencies to obtain a dispersion phase difference; and calculating the time delay using the obtained dispersion phase difference.

Abstract: The present application describes a method and system for determining a time delay between a transmission and a reception of an RF signal in a noisy environment. The method comprises: transmitting the RF signal; shifting a phase of the RF signal after a first time period of the transmitting of the RF signal, starting at a known transition time; receiving a received RF signal comprising a received phase shift corresponding to the shifting of the phase of the transmitted RF signal, the received phase shift occurring at a receive transition time equivalent to a sum of the time delay and the known transition time; determining the receive transition time by detecting a time corresponding to the received phase shift; and calculating the time delay using the receive transition time and the known transition time.