With Cappa C-Nav, Siemens Healthcare offers an optical navigation system that is especially suitable for spinal as well as trauma surgery. The picture for example shows the screw planning in C2-C1. Prior to the operation, the surgeon creates a 3D X-ray data set of the region of interest. This data set is used like a map for orientation during surgical intervention. The surgeon navigates during the operation by using so-called optical tracking via a special stereo camera. The surgeon is able to use the navigation system easily and by himself via a sterile user interface. The surgeon’s instruments and patient’s body region of interest are provided with differently arranged small reflecting marker spheres. The camera continuously acquires the position of these spheres and informs the navigation system of their location. This enables the surgeon to proceed with even greater accuracy during the operation by virtually testing the length of the screws, for example.