Fig. 1.

Radiological measurements. (A) The C2–7 lordotic angle (Cobb angle between the inferior endplate of C2 and C7) and segmental angle (Cobb angle between the upper endplate and the lower endplate of fused vertebral body) were measured in neutral position. (B-C) Upper segment range of motion and lower segment range of motion were calculated in both flexion and extension position. (D) Fused segment height was calculated as the distance between the midpoint of the upper margin of the upper vertebral body and the lower margin of the lower vertebral body at the appropriate surgical level. Upper segment disc height and lower segment disc height were measured along the line passing through the center of the vertebral bodies.