Patent ID: 8560047

Claim:
A method for performing a navigated freehand computer assisted surgical procedure on a knee of a patient, comprising the steps of: creating a three dimensional representation of a knee portion of a patient to which the procedure is to be performed; identifying a portion of the three dimensional representation corresponding to a bony portion of knee to be resected; identifying the orientation of a cutting plane for resecting the identified bony portion; displaying the three dimensional representation during the surgical procedure, wherein the step of displaying comprises: displaying the portion to be resected in a first color; displaying a boundary adjacent the portion to be resected in a second color that is different from the first color; and; displaying a portion of tissue adjacent the boundary, which is not to be resected, in a third color, which is different from the first and second colors; performing the navigated freehand surgical procedure using a navigated freehand surgical tool to resect the bony portion of the knee; tracking the real time position and orientation of the freehand surgical tool relative to the cutting plane; and displaying an indicator of the variation between the cutting plane and the real time position of the navigated freehand surgical tool, wherein the indicator is based upon the identified orientation of the cutting plane and the real time position of the navigated freehand surgical tool.