Fig. 1 (abstract P08).

The T1 pelvic angle (TPA) is defined as the angle between the line from the femoral head axis to the centroid of T1 and the line from the femoral head axis to the middle of the S1 superior endplate. The Global sagittal angle (GSA) was defined as the angle formed by a line from the midpoint of the 2 distal femoral condyles to the center of C7, and a line from the midpoint between the 2 distal femoral condyles to the posterior superior corner of the S1 endplate