Radiographic Measures of Spinal Alignment Are Not Predictive of the Development of C5 Palsy Following Anterior Cervical Discectomy and Fusion Surgery

The C2–C7 Cobb angle is defined by the angle made by the intersection of 2 lines, 1 going through the inferior endplate of C2 and the other going through the inferior end plate of C7 (A). The local Cobb angle (B) is defined by the angle made by 2 lines, 1 line going through the superior end plate of the top vertebral level and the other going through the inferior end plate of the bottom vertebral level being considered in the anterior cervical decompression and fusion. For both the C2–C7 and the local Cobb angle, lordotic angles are considered to be positive. The sagittal vertical axis (C) is the length of a perpendicular line drawn between a line drawn vertically down from the center of the dens and a line drawn vertically down from the inferior posterior end plate of C7. Vertebral segment height (D) is defined as the length of a line between the superior posterior end plate of the superior vertebrae and the inferior posterior end plate of the inferior vertebrae being considered. The C2–C7 cervical height (E) is the length of a line drawn between the inferior posterior end plate of C2 to the inferior posterior end plate of C7.