Fig. 1

Illustration of the coronal radiographic parameters including Cobb angle, L3IA and C7PL–CSVL. (Cobb angle, the superior surface of the upper vertebra and inferior surface of the lowermost vertebrae; C7PL–CSVL seventh cervical vertebra plumbline–central sacral vertical line, horizontal distance traveled by a plumb line dropped from the center of the C7 body to the midperpendicular of S1, L3IA third lumbar vertebra inclination angle, the angle between the upper endplate and a horizontal line at L3 body.)