Reformatting of Computed Tomography Scans Parallel to the S1 End Plate Increases Visualization of Trans Sacral Pathway in the First Sacral Segment, Especially With Dysmorphism.

OBJECTIVE

To determine whether reformatted computed tomography (CT) scans would increase surgeons' confidence in placing a trans sacral (TS) screw in the first sacral segment.

SETTING

Level 1 trauma center.

DESIGN

A retrospective cohort study.

PATIENTS/PARTICIPANTS: There were 50 patients with uninjured pelvises who were reviewed by 9 orthopaedic trauma fellowship-trained surgeons and 5 orthopaedic residents.

MAIN OUTCOME MEASUREMENTS

The overall percentage of surgeons who believe it was safe to place a TS screw in the first sacral segment with standard (axial cuts perpendicular to the scanner gantry) versus reformatted (parallel to the S1 end plate) CT scans.

RESULTS

Overall, 58% of patients were believed to have a safe corridor in traditional cut axial CT scans, whereas 68% were believed to have a safe corridor on reformatted CT scans ( P < 0.001). When grouped by dysplasia, those without sacral dysplasia (n = 28) had a safe corridor 93% of the time on traditional scans and 93% of the time with reformatted CT scans ( P = 0.87). However, of those who had dysplasia (n = 22), only 12% were believed to have a safe corridor on original scans compared with 35% on reformatted scans ( P < 0.001).

CONCLUSIONS

CT scan reformatting parallel to the S1 superior end plate increases the likelihood of identifying a safe corridor for a TS screw, especially in patients with evidence of sacral dysplasia. The authors would recommend the routine use of reformatting CT scans in this manner to provide a better understanding of the upper sacral segment osseous fixation pathways.