Ponticulus posticus is an abnormal bony bridge of posterior arch of atlas. The resulting foramen contains the vertebral artery and has clinical significance in lateral mass screw insertion into the first cervical vertebra. The authors report an atlantoaxial subluxation case showing a ponticulus posticus, which was surgically treated with posterior atlantoaxial screw fixation under the guidance of O-arm(R) imaging system coupled with navigation.
