Method and system for tracking tools in computer-assisted surgery

A system for tracking a bone-altering tool in computer-assisted surgery, comprising:

• a first trackable reference adapted to be secured to a first bone, with a first frame of reference being associated with the first trackable reference, the first frame of reference including landmarks and a coordinate system representative of the first bone;
• at least one sensor configured to track movements of the first trackable reference;
• a bone-altering tool without any trackable reference, the bone-altering tool adapted to be secured to the first bone in a secured configuration with the first trackable reference being at a first location on the first bone and the bone-altering tool being at a second location separate from the first trackable reference, the bone-altering tool having a bone-altering portion facing away from the first bone when the bone-altering tool is secured to the bone in said secured configuration, the bone-altering portion adapted to alter a second bone;
• a calculator to calculate at least an orientation of the first frame of reference;
• and
• an alteration parameter calculator to determine at least an orientation of the bone-altering tool in said secured configuration in the coordinate system as a function of the tracking of the first frame of reference and using a virtual model of the bone-altering tool, the virtual model of the bone-altering tool being registered in the coordinate system of the bone and including a virtual model portion of said bone-altering portion in the coordinate system, the alteration parameter calculator using a virtual model of the second bone to calculate an alteration of the second bone during alteration by the bone-altering portion of the bone-altering tool.