Fig. 2
From: Anatomy of the sacroiliac joints in children and adolescents by computed tomography
Fusion between sacral segments S1-S3 in a 14-year-old boy. Semi-coronal slice. Open space (no fusion) at the level S1/S2 – white arrowhead; partial fusion at the level S2/S3 – black arrowhead. Note also ossified nucleus antero-superior at S1 (white arrow) and lateral to the intervertebral space S1/S2 (black arrow) on the right side