SURGICAL INSTRUMENT INCLUDING HOUSING, A CUTTING ACCESSORY THAT EXTENDS FROM THE HOUSING AND ACTUATORS THAT ESTABLISH THE POSITION OF THE CUTTING ACCESSORY RELATIVE TO THE HOUSING

There is disclosed a method for performing a procedure on a patient's knee, said method comprising: establishing a virtual boundary associated with a patient's femur; providing access through skin to the patient's femur; manually holding an instrument having a hand-held portion, a saw blade, a plurality of actuators for moving the saw blade in a plurality of degrees of freedom relative to the hand-held portion, and a tracking device; operating a tracking and control system for the instrument to track movement of the saw blade relative to the virtual boundary; moving the saw blade through an incision in the skin; cutting away material from the patient's femur wherein the tracking and control system controls the actuators to move the saw blade relative to the hand-held portion so that the saw blade is substantially maintained in a desired relationship to the virtual boundary during cutting; and fitting an implant into the patient's femur after cutting away material from the patient's femur. 25622233.1:DCC