Fig. 1

Upper left A) the upper conjugate (UC) was defined as the distance from the innermost aspect of the top of the symphysis pubis to the sacral promontory on the mid-sagittal plane; B) the pelvic depth (PD) was described as the distance between the promontorium and the lower symphysis pubis; C) The lower conjugate (LC) was defined as the distance from the lower symphysis pubis to the sacrococcygeal junction determined on the mid-sagittal plane. Upper right A) The symphysis angle (SA) was described as the angle between the long axis of the symphysis and the horizontal midsagittal plane. B) The apical depth (AD) was described as the distance between the highest point of the symphysis to the prostatic apex down left. Down left A) Bone femoral width (BFW) was mesasured as the bony width of the pelvis at the mid femoral head level. B) Interspinous distance (ISD) was measured on the axial plane between the tips of the ischial spines. Downright A) The soft tissue width (SW) was measured as the narrowest distance between the levator muscles on the axial CT images