Obturator-outlet and obturator-inlet views and iliac oblique intraoperative views guide accurate screw insertion. A, Bone corridor between posterior superior iliac spine and anterior inferior iliac spine, in which iliac screws are ideally placed, projects as teardrop on combination obturator-outlet oblique image. B, Screw is extraosseous if it extends beyond cortical boundary of radiographic teardrop. Intraosseous screw placement between inner and outer tables of ilium can also be guided and confirmed with obturator-inlet oblique view. C, Iliac oblique image ensures accurate screw length and appropriate location above greater sciatic notch. D, Two iliac screws positioned parallel or more cephalad (E) can be used for placement of second iliac screw, yielding triangular configuration. (From Shildhauer TA, Bellabara C, Nork SE, et al: Decompression and lumbopelvic fixation for sacral fracture-dislocations with spino-pelvic dissociation, J Orthop Trauma 20:447, 2006.) SEETECHNIQUE 41.19.