If a transverse fx is seen check for a post wall fx on the obturator oblique view. Triangle shaped and inferolateral from SI joint. Only seen c medial displacement. Transverse Fx from front to back thru acetabulum, dividing into upper and lower halves.
Oblique views show it crossing both columns.
Superior fragment above fx line is similar to elementary transverse fx but the obturator ring is disrupted and the inferior portion of the acetabulm is fractured into anterior and posterior pieces.