Abstract
The anatomy of joints provides an important basis for understanding the nature and
imaging of pathologic lesions and their imaging appearance. This applies especially
to the sacroiliac (SI) joints, which play a major role in the diagnosis of spondyloarthritis.
They are composed of two different joint portions, a cartilage-covered portion ventrally
and a ligamentous portion dorsally, and thus rather complex anatomically. Knowledge
of anatomy and the corresponding normal imaging findings are important in the imaging
diagnosis of sacroiliitis, especially by MR imaging. A certain distinction between
the two joint portions by MR imaging is only obtainable by axial slice orientation.
Together with a perpendicular coronal slice orientation, it provides adequate anatomical
information and thereby a possibility for detecting the anatomical site of disease-specific
characteristics and normal variants simulating disease. This overview describes current
knowledge about the normal macroscopic and microscopic anatomy of the SI joints.
Keywords
sacroiliac joint - normal anatomy - histology - MR imaging
