Systematic review of sacroiliac joint motion and the effect of screw fixation.

Abstract Background: Pelvic injuries that disrupt the sacroiliac joints often require surgical intervention to restore stability. Quantitative characterization of sacroiliac motion in response to physiologic loading provides important metrics of adequate fixation in the evaluation of newly emerged fixation techniques. The objective of this study was to systematically review and evaluate biomechanical evidence on the motion of the sacroiliac joint in its normal, destabilized, and stabilized states. Methods: We searched the PubMed database for studies available until June 2020 using keywords: sacroiliac, biomechanic*, and fixation. Publications of any in vivo or in vitro biomechanical study that included measurements of the range of motion at the sacroiliac joint were considered. Findings: We identified and screened 176 total records, and 13 articles of them met inclusion criteria and were used in this review. The average sacroiliac joint range of motion of the intact pelvis was 1.88° in flexion/extension, 0.85° in lateral bending, 1.26° in axial rotation. Of the 13 studies, four reported sacroiliac motion from a destabilized state, while seven reported the motion after stabilization. A forest plot of the stabilized data set in flexion/extension showed that while the heterogeneity was poor, the weighted effect size of the changes from the intact state to the stabilized state was 0.0%. Interpretation: Quantitative evidence on sacroiliac joint motion relating to pelvic injuries or fixation is limited. Our results indicate that the pooled intact range of motion from the literature may serve as a viable reference to quantify the effectiveness of new stabilization techniques. Level of evidence: Level V, systematic review. Study type: Therapeutic- investigating the results of a treatment.