Lateral cervical radiograph showed fracture at the base of odontoid process of axis/C2. Anterior displacement of the fractured odontoid process with grade 2 anterolisthesis over the C2 body (50% AP width).
Tip of odontoid process projects above foramen magnum in keeping with basilar invagination. It is evidenced by abnormal measurement with McRae line (the odontoid process is above this line), Chamberlain line (line connecting the posterior border of hard palate and opisthion - the tip of odontoid process is 4mm above this line (<3mm)) and McGregor line (line connecting posterior border of hard palate and most caudal point of occipital curve- the tip of odontoid process measures 6mm above this line (<5mm)).