The pediatric accessory sacroiliac joint: does it exist?

Objective: Determine the prevalence of the accessory sacroiliac joint in the pediatric population and describe variant sacroiliac joint morphology that may predispose patients to the development of an accessory sacroiliac joint. Materials and methods: One hundred and seventy-eight high-resolution pelvic CT scans of patients aged 0 to 15 years were reviewed for the presence of an accessory sacroiliac joint. Patients were stratified based on age and gender. Morphology of the sacroiliac joints was detailed to assess the degree of curvature in the expected characteristic location of the accessory sacroiliac joint. Results: No accessory sacroiliac joint was identified on any of the pediatric pelvic CT scans. The sacroiliac joints demonstrated varying degrees of unilateral or bilateral curvature in the expected region of the accessory sacroiliac joint which increased in both severity and prevalence with age. Conclusion: The pediatric accessory sacroiliac joint may not exist and is unlikely to be a congenital variant present at birth. However, curvature of the sacroiliac joint in the expected location of the accessory sacroiliac joint which increases in severity and prevalence with age may predispose patients to the formation of an accessory sacroiliac joint later in life.