A standardized method of measuring screw breach on postoperative computed tomography scans following percutaneous fixation of the posterior pelvic ring.

Purpose: To assess the reliability of a standardized measurement of screw breach on postoperative computed tomography (CT) scans following percutaneous fixation of the posterior pelvic ring.

Methods: Three orthopedic trauma surgeons independently utilized a standardized method of measuring posterior pelvic ring screw breaches on post-operative CT scan images. Breaches were measured as a continuous variable on sagittal images reformatted to be perpendicular to the screw on axial images. The inter-rater and intra-rater reliability of screw breach distance measurements was assessed.

Results: Measurements were performed on 42 screws in 20 patients. Screw types included S1-iliosacral (IS) (n = 16), S1-transsacral (TS) (n = 8), S2-IS (n = 2), and S2-TS (n = 16). Patients with varying degrees of screw breaches were chosen to test measurements across breach severities, including 0 mm (n = 10), ≤ 2 mm (n = 12), > 2 to 4 mm (n = 11), and > 4 mm (n = 9). The mean difference and 95% confidence interval (CI) between screw breach measurements between the three surgeons was - 0.13 mm (CI - 0.48 to 0.20), 0.05 mm (CI - 0.6 to 0.7), and 0.18 mm (CI - 0.47 to 0.85), respectively. The inter-rater reliability of the measurements was considered excellent (intraclass correlation coefficient (ICC), 0.93). The mean intra-rater reliability for the observers was considered good (ICC 88.5, CI 82 to 95).

Conclusions: This simple standardized method of measuring screw breaches had excellent inter-rater reliability and would support comparisons of screw breach severity across studies.

Level Of Evidence: Level III.