Finite element analysis of sacral-alar-iliac screw fixation for sacroiliac joint dislocation.

The percutaneous sacroiliac (SI) screw is a common fixation option for posterior ring disruption in pelvic fractures. However, SI screw placement is difficult and can injure adjacent neurovascular structures. The sacral-alar-iliac screw (SAI) is a safe, reliable free-hand sacral pelvic fixation technique. To investigate the biomechanical stability of SAI for sacroiliac joint dislocation, finite element analysis was performed in unstable Tile type B and C pelvic ring injuries. The displacement in S1 (fixation of a unilateral S1 segment with one SI screw), TS1 (fixation of the S1 segment with a trans-sacra l1 screw), TS2 (fixation of the S2 segment with a trans-sacra 2 screw), S1AI, and S2AI exceeded the normal sacroiliac joint mobility. Sufficient stability after sacroiliac joint dislocation was obtained with (TS1+TS2), (TS2+S1), (S1AI+S2AI+rod), (S1AI+S2AI), and (S1+S2AI+S1 pedicle) fixation. The TS1+TS2 group had the smallest displacement and lowest peak screw stress, followed by (S1+S2AI+S1 pedicle) placement. Our findings suggest that SAI screws are a valuable option for sacroiliac joint dislocation. This article is protected by copyright. All rights reserved.