Are Anterior Plates More Effective than Iliosacral Screws to Fix the Sacroiliac Joint? Biomechanical Study

Introduction  Sacroiliac joint dislocations are caused by high energy trauma and commonly treated with the iliosacral screw fixation or the anterior plating of the sacroiliac joint (SIJ). However, there is a lack of consensus regarding which procedure is the most successful in treating sacroiliac joint dislocations. This aims to compare stiffness and maximum load of pelvises with sacroiliac joint dislocations treated with both procedures in a synthetic bone model. Methods  Synthetic pelvises were mounted and divided into 2 treatment groups ( n  = 5): a model with two orthogonal plates placed anteriorly to the SIJ (PPS group) and another with two iliosacral screws fixating the SIJ (SPS group), both with pubic symphysis fixation. The maximum load supported by each sample was observed and the stiffness was calculated from the curve load vs displacement. The mean values of load to failure and stiffness for each group were compared with the Mann-Whitney U test ( p  < 0.05 was considered significant for all analysis). Results  The mean load to failure supported by the PPS group was 940 ± 75 N and the SPS was 902 ± 56 N, with no statistical difference. The SPS group showed higher values of stiffness (68.6 ± 11.1 N/mm) with statistical significant difference in comparison to the PPS sample (50 ± 4.0 N/mm). The mode of failure was different in each group tested. Conclusion  Despite lower stiffness, the anterior plating fixation of the sacroiliac joint can be very useful when the iliosacral screw fixation cannot be performed. Further studies are necessary to observe any differences between these two procedures on the clinical and surgical setting.