Identification of Safe Channels for Screws in the Anterior Pelvic Ring Fixation System

Abstract Background: There have been few studies on insertion of fixation screws for the anterior pelvic ring system. Objective: To identify safe channels for fixation screws in the anterior pelvic fixation system. |Methods: Screw insertion was simulated into a total of 40 pelvic finite element models as well as 16 fresh pelvic specimens and the channel parameters were measured. Results: Finite elements (male, female): screws in ilium: length 114.4 ± 4.1 and 107.6 ± 8.3 mm, respectively; diameter 11.7 ± 0.5 and 10.0 ± 0.6 mm, distance between screw and anterior inferior iliac spine: 5.5 ± 1.0 and 5.6 ± 1.0 mm, angle of coronal plane 55.8 ± 2.4 degrees and 50.6 ± 3.1 degrees, angle of sagittal plane 26.6 ± 1.0 degrees and 24.5 ± 1.9 degrees and angle of horizontal plane 64.9 ± 3.7 and 58.1 ± 3.1. Screws in pubis: length 47.0 ± 2.0 and 39.8 ± 3.9 mm, diameter 7.1 ± 0.4 and 6.1 ± 0.4 mm. Specimens (male, female): distance between screw and anterior inferior iliac spine: 5.5 ± 0.5 and 5.6 ± 0.7 mm, angle of coronal plane 55.9 ± 1.3 degrees and 50.7 ± 1.5 degrees, angle of sagittal plane 26.7 ± 0.5 degrees and 24.1 ± 0.9 degrees and angle of horizontal plane 64.8 ± 0.6 degrees and 58.8 ± 0.8 degrees. Comparison between female and male in each group: differences in distances between screws and anterior inferior iliac spine and median line of symphysis pubis (P > 0.05) were not statistically significant; differences in the remaining parameters were statistically significant (P < 0.05). Conclusions: If surgeons payed attention to sex differences, select screws of appropriate diameter and length, and hold the insertion position and direction, screws in the anterior pelvic ring fixation system could be safely inserted.