Fig. 4.

Photo model depicts the principles of ATPS fixation. Left one depicts sagittal plane of C6 vertebra; right one depicts transverse plane of C6 vertebra from cryosections. Note transverse intersection point of ATPS with anterior vertebral body close to mid-sagittal line, insertion of ATPS albeit parallel to upper vertebral endplate in sagittal plane, and crossing configuration of ATPS and vertebral body screw in transverse plane, respectively. Asterisk marks vertebral artery. Cryosections with kindly permission from A. Kathrein, M.D., University of Innsbruck/Austria