Fig. 1

A Sagittal radiologic parameters: Thoracic Kyphosis (TK) measured from the superior endplate of T4 to the inferior endplate of T12 by Cobb method; Lumbar Lordosis (LL) measured from the superior endplate of L1 to the inferior endplate of S1 by Cobb method. Sagittal vertical axis (SVA) defined as the horizontal offset from the posterosuperior corner of S1 to the plumb line going through the vertebral body of C7. B Pelvic parameters: Sacral slope (SS): the angle between the horizontal line and the sacarl endplate; Pelvic tilt (PT): the angle between the vertical and the line through the midpoint of the sacral endplate to the femoral heads axis; Pelvic Incidence (PI): the angle between the perpendicular to the sacral plate at its midpoint and the line connecting this point to the femoral heads axis