Fig. 2

Sagittal Spinal radiologic parameters. TK is the angle between the cranial endplate of T4 and the caudal endplate of T12. LL is the angle between the upper endplate of L1 and the sacral endplate. SVA is the horizontal offset from C7 plumb line (C7PL) to the postero-superior cornor of S1. T1SPI is the angle between vertical and a line from the center of the femoral head axis to the center of the T1 vertebral body. PI is the angle between the line perpendicular to the sacral plate at its midpoint and the line connecting this point to the axis of the femoral heads. PT is the angle between the line connecting the midpoint of the sacral plate to the femoral heads axis and the vertical