Figure 1.

Spino-pelvic radiographic parameters measured on a lateral lumbar radiograph of an individual with high-grade spondylolisthesis (HGS). Lumbar lordosis (LL) is the sagittal Cobb angle measured between the superior end plate of L1 and the superior end plate of S1. The sacral slope (SS) is measured by creating an angle between the center of the sacral plateau and the horizontal. The pelvic tilt (PT) is measured as the angle between the line passing through the center of the femoral heads and the center of the sacrum. The pelvic incidence (PI) is measured as the angle between a line drawn perpendicular to the sacral end plate at its midpoint and a line drawn from the midpoint of the sacral end plate to the midpoint of the femoral head axis.