a-b. (a)Pelvic tilt: the difference in height between the DR and the DL (right crista iliaca posterior superior [DR], and left crista iliaca posterior superior [DL]) measured in millimeters. The angle between the vertical passing through DR and DL to the horizontal reference plane was defined as angular measure in degrees. (b) Pelvic torsion was measured by the angle between the surface normals to the lumbar dimples indicating the spina iliaca posterior superior landmark. In a symmetric pelvis without torsion of the iliac bones, pelvic torsion angle is 0. The angle is positive if the normal to the right dimple points lower than the normal to the left dimple, indicating the DR to be rotated backward whereas the DL is rotated forward. Tracted by the paper referenced in .