Comparison of stability of sacroiliac screws in the treatment for unilateral Tile C sacral fractures between different modalities in a 3-dimensional finite element model

Abstract

Objective To study the stability of sacroiliac screws fixation for the treatment of unilateral vertical sacral fractures in order to provide pratical manipulation and reference for rapid insertion of sacroiliac screws in case of emergency.Methods A 3-dimensional finite element model of Tile C pelvic ring injury (unilateral type Denis Ⅱ fracture of sacrum) was made in a 36 year of a female patient.The unilateral sacral fractures were fixed in 3 types with sacroiliac screws in models respectively.The shift and angle displacement of the central superior surface of sacrum in the case of upright standing on both feet were measured and compared.Results The stability fixation with two sacroiliac screws for double planes of S1 and S2 segments was markedly superior to fixation with one sacroiliac screw for single plane of S1 or S2 segment; The vertical and rotational stability of sacroiliac screw fixation in S2 was superior to that in S1.Conclusions Fixation with two sacroiliac screws for double planes of S1 and S2 segments should be utilized for the fixation in unilateral sacral fractures of Tile C pelvic ring injury as possible.If only one sacroiliac screw is implanted,the fixation in S2 segment is more recommended than that in S1. Key words: Pelvis ; Sacral fracture ; Sacroiliac screw ; Stability ; 3-dimensional finite element