Surgical Navigation System

A surgical navigation method for indicating an alignment of a surgical instrument, the method comprising the steps of:

• a. providing a surgical navigation system including (i) a computer and display, (ii) data representing a 3D radiological image of a patient surgical site, (iii) an instrument guide having a first marker array, (iv) the surgical instrument having a second marker array, and (v) an optical sensor configured to detect markers on the first and second marker arrays;
• and
• b. aligning the instrument guide by positioning the instrument guide in the general position of a pre-established trajectory line using the display, which displays (i) a two-dimensional disc representing the pre-established trajectory line and (ii) a three-dimensional cylinder representing the guide trajectory line, such that alignment between the pre-established trajectory line and the guide trajectory line is achieved when the three-dimensional cylinder is aligned with and fits within a central circle of the two-dimensional disc.