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 the fused vertebral body) were measured in the neutral position. (B and C) The upper segment ROM and lower segment ROM were calculated in both flexion and extension positions. (D) The 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. ROM, range of motion.