Location of Vascular Structures at Risk in Relation to Sacroiliac Joint Fusion.

Study design: Retrospective cohort.

Objective: This study seeks to establish the normal distribution of the vasculature surrounding the SI joint while also demonstrating associations between distribution and laterality, sex, and ethnicity.

Summary of background data: Sacroiliac (SI) joint fusion surgery has emerged as a viable treatment option for patients suffering from low back pain due to chronic SI joint dysfunction. Due to potential complications from iatrogenic injury to vasculature, it becomes critical to understand normal anatomy and locations with a high vasculature concentration surrounding the SI joint.

Methods: The authors retrieved medical and radiographic records of patients who underwent computed tomography angiography (CTA) of the pelvis. Anterior and posterior compartments of the SI joint were established on the transverse view by creating an even coronal division of the SI joint. The superior, middle, and inferior compartments were established on the coronal view as three equal transverse compartments. The compartments in which vasculature was visualized were recorded.

Results: Distribution of vasculature around the right and left hemipelvis concentrated in the inferior compartments and decreased in concentration while moving superiorly. Anterior compartments contain a higher vascularity than posterior compartments. Vasculature was present in <3% of the posterior middle, and posterior superior compartments while present in >83% of the inferior compartments. There were no significant differences with respect to vascular distribution when comparing the laterality of the right versus left hemipelvis. There were statistically significant relationships between vascular distribution and sex (P<0.05), as well as across self-reported ethnicity (P<0.05).

Conclusions: SI screw placement in the posterior superior has the lowest risk of iatrogenic vascular injury. Careful consideration should be taken during SI joint fusion surgery in the inferior compartments due to its high vasculature density.