Fig. 6.

Ideal screw placement in ATS (oversized screw lengths shown). a, b Screw entry point is to be chosen at the pinafore C2 for the first and a bit posteriorly underneath the pinafore C2 for the second screw to prevent screw cut-out anteriorly. c The screws should direct to the lateral rim of the lateral mass C1. d Image depicts plane of view in (e). e Ideal screw placement inside C1-2. f A cerclage wire surrounding the Isthmus C2 with the X-ray beam in direction to its angulation: the medial cortical border of Isthmus C2 resembles a possible lateral threshold for screw angulation