Fig. 1

TK: The angle between the upper endplate of T4 and the lower endplate of T12; LL was measured using the Cobb angle between the superior end plate of the L1 and S1. PT was defined as the angle between a straight line connecting the midpoint of the bilateral femoral head centre to the midpoint of the sacral plate and the plumb line. PI was defined as the angle between the perpendicular line of the sacral plate and the line of the midpoint of the superior endplate of S1 joining with the centre of the hip axis. SS was defined as the angle formed by the upper endplate of S1 and the horizontal plane; SVA:C7 vertebral body along the vertical line and the upper edge of the S1 vertebral body