Lateral X-rays of the cervical vertebra. Cobb C: the Cobb angle between the lines perpendicular to the upper end plate of the C2 vertebral body and the lower end plate of the C7 vertebral body. Cobb S: the angle between a line perpendicular to the superior border of the upper affected vertebral body and the inferior border of the lower affected vertebral body. TIH: total interbody height