Fig. 3

The measurement of radiological parameters. Cobb angle of main curve (MC), coronal balance (CB), sagittal vertical axis (SVA), pelvic tilt (PT), lumber lordosis (LL) and pelvic incidence (PI). A. Cobb angle of main curve (MC): the greatest cobb angle at main curve of the spine, measured from the upper endplate of a upper vertebra to the lower endplate of a lower vertebra; B. Coronal balance (CB): the horizontal distance between C7 plumb line and center sacral vertical line; C. Sagittal vertical axis (SVA): the vertical distance between C7 plumb line and the upper back corner of the S1 endplate; D. Pelvis tilt (PT) and: the angle between lines originating at the bicoxofemoral axis and extending vertically and to the middle of the superior endplate of S1, pelvic incidence (PI): angle between a line perpendicular to the superior endplate of S1 and the line connecting the superior endplate of S1 to the bicoxofemoral axis; E. lumber lordosis (LL): the Cobb angle between the upper endplate of L1 and the upper endplate of S1;