2 PARALLEL LINEAR DENSITIES ON LATERAL RADIOGRAPHS OF THE LUMBOSACRALSPINE - NEITHER ILIOPECTINEAL LINES NOR BASIS OSSIS SACRI

Two parallel radiodense lines are constantly seen on lateral radiograp hs of the lumbosacral spine. Whether they originate from the pelvis or sacrum is unclear. Using metallic wire markers, we performed a radiog raphic investigation on bony skeletons to define their origins and ana tomical locations. Our study demonstrates that each arises from the sh arp, well-defined bony ridge which forms the anterosuperior boundary o f the auricular surface for articulation with the sacrum on either sid e. Each ridge lies along the medial border of the iliac fossa and repr esents an increase in compact bone in response to weight transmission. These lines have useful applications for they provide fixed radiograp hic landmarks on the bony pelvis for certain angular measurements in o rthopaedics.