Fig. 2.
a Lateral cervical X-ray demonstrates if odontoid has bigger screw angle, anterior-inferior third cervical vertebra needs to be rimmed. Dotted arrow screw; white arrow third cervical vertebra’s rimmed area. b Lateral cervical X-ray demonstrates if odontoid has smaller screw angle, anterior-inferior third cervical vertebra does not need to be rimmed. Dotted arrow screw