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: There is provided a method for intra-operatively presenting an approximate model of an anatomical structure by collecting a cloud of small surfaces. The cloud of small surfaces is gathered with a registration pointer having an adapted tip capable of making contact with the surface of an anatomical structure and registering the normal at the point of contact.

Abstract: An interface apparatus (20) for tracking by a tracking system (40) of an object(s) in space for position and orientation and for interacting with the tracking system (40). The interface apparatus (30) comprises passive detectable devices (12,14,16,22) trackable for position by the tracking system (40). A mounting device (10,24) receives the passive detectable devices (12,14,16,22) in a known geometry, and is secured to the object(s) such that a position and orientation of the object(s) is calculable by the tracking system (40) as a function of a tracking of the known geometry of the passive detectable devices (12,14,16,22). One of the passive detectable devices (22) is displaceable with respect to the object(s). A displacement of the passive detectable device (22) with respect to the object(s) is detectable to initiate an interaction with the tracking system (40) while maintaining the tracking of the object(s).

Abstract: There is described a method of manufacturing a device to be used with a computer-aided surgery system, a method of calibrating the device, and the device itself. After fabrication, the device is measured to obtain true parameters thereof. The true parameters are stored on a storage medium associated with the device and include measurement data of high precision relating to dimensions of the device as well as to relative positioning of a tracker on the device with respect to the device. The true parameters are entered into the system and when the tracker is located in the 3D environment, the device can then be located in the 3D environment with a high degree of precision using the true parameters.

Abstract: A system for tracking an object in space for position, comprises a transponder device connectable to the object. The transponder device has one or several transponder aerial(s) and a transponder circuit connected to the transponder aerial for receiving an RF signal through the transponder aerial. The transponder device adds a known delay to the RF signal thereby producing an RF response for transmitting through the transponder aerial. A transmitter is connected to a first aerial for transmitting the RF signal through a first aerial. A receiver is connected to the first, a second and third aerials for receiving the RF response of the transponder device therethrough. A position calculator is associated to the transmitter and the receiver for calculating a position of the object as a function of the known delay and the time period between the emission of the RF signal and the reception of the RF response from the first, second and third aerials. A method is also provided.

Abstract: There is described a method for determining a mechanical axis of a femur using a computer aided surgery system having an output device for displaying said mechanical axis, the method comprising: providing a position sensing system having a tracking device capable of registering instantaneous position readings and attaching the tracking device to the femur; locating a center of a femoral head of the femur by moving a proximal end of the femur to a first static position, acquiring a fixed reading of the first static position, repeating the moving and the acquiring for a plurality of static positions; and locating the centre by determining a central point of a pattern formed by the plurality of static positions; digitizing an entrance point of the mechanical axis at a substantially central position of the proximal end of the femur; and joining a line between the entrance point and the center of rotation to form the mechanical axis.

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 system for tracking an object in space for position, comprises a transponder device connectable to the object. The transponder device has one or several transponder aerial(s) and a transponder circuit connected to the transponder aerial for receiving an RF signal through the transponder aerial. The transponder device adds a known delay to the RF signal thereby producing an RF response for transmitting through the transponder aerial. A transmitter is connected to a first aerial for transmitting the RF signal through a first aerial. A receiver is connected to the first, a second and third aerials for receiving the RF response of the transponder device therethrough. A position calculator is associated to the transmitter and the receiver for calculating a position of the object as a function of the known delay and the time period between the emission of the RF signal and the reception of the RF response from the first, second and third aerials. A method is also provided.

Abstract: A drill guide assembly (10) for a drilling tool (50) having a chuck engaging a bit portion (54) comprising a tip (62) and a length extending from the chuck, the drill guide assembly comprising a first member (14), a second member (12) and a trackable member (16). The first member (14) is adapted to abut a workpiece surface and defines a central aperture (19) therethrough adapted to receive the bit portion. The second member (12) is adapted to be axially displaced with respect to the first member and is axially biased therefrom, and defines a central aperture (11) therethrough adapted to receive the bit portion. The trackable member (16), fastened to the second member, comprises a detectable element (35) adapted to be located and tracked in three dimensional space, thereby defining the position and movement of the second member and therefore that of the drilling tool bit portion.

Abstract: A method of calibrating a circular portion of an object, such as to determine the center point of the object, is provided. The method includes determining spatial coordinates of at least two points on a circumferential edge of the circular portion of the object, and calculating the center point of the circular portion using the spatial coordinates of the two points and a geometric parameter representative of the diameter of the circular portion. A calibration device and system are also provided for use with a computer tracking system in order to calibrate such an object having a circular portion.

Abstract: A registration pointer for registering points of surfaces of bodily elements in computer-assisted surgery, comprising a handle for being manipulated by a pointer operator. A stem is connected to the handle and has a first and a second tip configurations each having a respective use relating to a registration of points on specified bodily elements. A detectable device is secured to the stem, and is adapted to be tracked in space for position and orientation by a sensing apparatus. A position of the tip configurations with respect to the detectable device is determinable such that a position of the tip configurations is calculable as a function of the position and orientation of the detectable device. The tip configurations are chosen to register points on given bodily elements as a function of the respective use, by recording a position of points of contact between the tip configurations and the given bodily element.

Abstract: A surgical device adapted for use with an image guided surgical system to facilitate monitoring inter-dependently mobile bone elements. A rigidly connected multiple-point anchor assembly is releasably engageable to at least two inter-dependently mobile bone elements and immobilizes the bone elements such that no relative movement therebetween is possible, and a complex rigid body comprising the immobilized bone elements and the multiple-point anchor assembly is formed. A trackable member is fastened to the multiple-point anchor assembly and comprises a detectable element adapted to be located and tracked in three dimensional space by the image guided surgical system, thereby defining position and movement of the complex rigid body.

Abstract: A system for automatic calibration of instruments (S) having varying cross-sectional dimensions within a predetermined range and having detectable elements (110, 112, 113, 114) thereon for computer-aided surgery, comprising a calibration base (C) having detectable elements (43, 44, 46, 48) secured thereto for detecting a position and an orientation thereof in space by sensors (204) connected to a position calculator (202). The calibration base is adapted to receive and to releasably secure a working shaft (100) of any of the instruments (S) and provides an abutting surface (14) for a tip (102) thereof in such a way that a position and orientation of the tip (102) of the instrument (S) secured therein is calculable when working shaft cross-section dimensions thereof are known. The position calculator (202) receives instrument data (214) and calibration data (218) from an operator through a user interface (206) and stores the instrument data (214) and calibration data (218) for subsequent calibrations.

Abstract: A method and an apparatus are described for placing multiple implants during a surgery, the apparatus comprising: a display for an image representing a patient's anatomy; a database of virtual implants from which a user selects; a tool for the user to manipulate in order to select the virtual implants from the database and place the virtual implants in the image at desired locations; and a positioning module for calculating a position of a first of the virtual implants with respect to a second of the virtual implants and allow the user to align the first and second virtual implants with respect to each other, for generating relative position data as a function of the calculated position, and for sending the relative position data to the display.

Abstract: A drill guide assembly for a drilling tool having a chuck engaging a bit portion comprising a tip and a length extending from the chuck, the drill guide assembly comprising a first member, a second member and a trackable member. The first member is adapted to abut a workpiece surface and defines a central aperture therethrough adapted to receive the bit portion of the drilling tool. The second member is adapted to be axially displaced with respect to the first member and is axially biased therefrom, and defines a central aperture therethrough adapted to receive the bit portion of the drilling tool. The trackable member, fastened to the second member, comprises a detectable element adapted to be located and tracked in three dimensional space, thereby defining the position and movement of the second member and therefore that of the bit portion of the drilling tool.

Abstract: A surgical bone reference assembly is communicable with an image guided surgical system such that position and movement of a bone element are monitorable. A bone anchor member comprises a trackable member and teeth engageable with the bone element. The trackable member comprises a detectable element adapted to be located and tracked in three dimensional space by the image guided surgical system, thereby defining position and movement of the trackable member. A protective guide member is used with the bone anchor member such that the bone anchor member is insertable through soft tissue covering the bone element without causing significant damage thereto. The bone anchor member is engageable with the bone element, such that the teeth are forced into engagement with the bone element and the bone anchor member is fastenable to the bone element in a fixed relation thereto.

Abstract: A system and a method for performing a computer assisted surgery (CAS) uses an expert system driven graphical user interface (GUI) that displays a series of display pages that provide information related to respective steps required to perform the surgery. The system displays virtual images of surgical instruments used during the surgery, overlaid on fluoroscopic images of the implant site to assist the surgical team during instrument calibration, and implant preparation and installation. The GUI presents the surgical team with a succession of options that the surgical team responds to using affirmation and negation actions. These actions are associated with an icon presented in a same region of the display pages, and are annotated with text relevant to an immediately presented option, permitting a substantial portion of the CAS to be effected using a foot-operated input device.

Abstract: A registration pointer for registering points of surfaces of bodily elements in computer-assisted surgery, comprising a handle for being manipulated by a pointer operator. A stem is connected to the handle and has a first and a second tip configurations each having a respective use relating to a registration of points on specified bodily elements. A detectable device is secured to the stem, and is adapted to be tracked in space for position and orientation by a sensing apparatus. A position of the tip configurations with respect to the detectable device is determinable such that a position of the tip configurations is calculable as a function of the position and orientation of the detectable device. The tip configurations are chosen to register points on given bodily elements as a function of the respective use, by recording a position of points of contact between the tip configurations and the given bodily element.

Abstract: A computer system and a method for performing a computer assisted surgery uses an expert system driven graphical user interface (GUI) that displays a series of visual display screens that provide information related to respective steps required to perform the surgery. The system displays virtual images of surgical instruments used during the surgery, as well as computer enhanced images of the implant site to assist the surgical team during instrument calibration, implant site planning, implant site preparation, and implant installation.

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