Fig. 1
From: Correlating preoperative imaging with intraoperative fluoroscopy in iliosacral screw placement
Preoperative CT scan with sagittal reconstruction. The image has been rotated 90° from vertical to simulate the patient lying supine on the operating room table. The yellow line parallels the anterior cortex of the S1 body with which the fluoroscopic beam would parallel for an inlet view. The anatomic variability of the posterior pelvic ring is demonstrated above in four different patients. Note the near vertical orientation of the S1 sacral body in a. There is a gradual increase in the lordotic alignment in b and the S1 body is nearly horizontal in d (color figure online)