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.