Abstract: A computer-assisted surgery system for tracking an object during surgery comprises a first tracker device and a second tracker device secured to different parts of the object. The first and the second tracker device are secured to the object separately in such a way that a geometrical pattern is defined with trackable elements from the first tracker device and from the second tracker device. A tracking system has a sensor unit tracking the trackable members. A calibration unit defines a geometrical pattern from the trackable members. A pattern identifier identifies the geometrical pattern. A position and orientation calculator calculates a position and orientation of the geometrical pattern The tracking system calculates position and orientation of the object as a function of the position and orientation of the geometrical pattern and of object/geometrical pattern relation data gathered during surgery.

Abstract: A surgical reference device for use with a computer-assisted surgery system comprises an engaging member adapted to engage directly on soft tissue of a body part such that substantially no relative movement is possible between the engaging member and a bone element of the body part. A trackable member is attached to the engaging member and comprises a detectable element for being located and tracked in three-dimensional space by the computer-assisted surgery system to measure a position and an orientation of the trackable member in time, whereby the bone element is tracked as a function of the position and orientation of the trackable member. A method for tracking a position and an orientation of a bone element using a computer-assisted surgery system is also provided.

Abstract: A navigation system for tracking an object during surgery, comprises markers adapted to be connected to an object in a known relation. An optical camera detects a light signal from the at least one marker, the optical camera generating tracking data associated with a position of the markers from the light signal. A transparent shield is positioned between the optical camera and the markers during surgery to allow the optical camera to be within the sterile field. Calibration data is associated with an effect of the shield on the light signal passing therethrough to be detected by the optical camera. A position and orientation calculator calculates a position and/or orientation of the object as a function of the tracking data, of the calibration data, and of the known relation between the object and the markers. A method is provided for tracking an object in computer-assisted surgery.

Abstract: A computer-assisted surgery system for tracking an object during surgery comprises two trackable devices secured to two parts of an object. The devices each have optical elements arranged in geometrical patterns. The devices are secured separately to the object so that the devices are at least partially detectable from an overlapping range of directions, so that a combinative geometrical pattern is defined from a combination of at least part of the optical elements from the trackable devices. A sensor unit detects tracking data on any tracked geometrical pattern. A pattern identifier identifies, from known pattern data for the geometrical patterns, which of the geometrical patterns is being tracked. A position and orientation calculator calculates position and orientation of the object as a function of tracking data on an identified geometrical pattern and of a known spatial relation between the identified geometrical pattern and the object. A method for tracking an object is also provided.