Table 3 Typical sites of active inflammation and chronic changes of the spine in spondyloarthritis
Spondylitis (involvement of vertebral bodies)Typically located within bone marrow at one or more of the four corners of vertebral bodies. If located at the corners: spondylitis anterior ( = Romanus lesion) or spondylitis posterior
Spondylodisciitis (involvement of intervertebral discs)Located within bone marrow at cortical plate adjacent to intervertebral disc (Andersson lesion)
Arthritis of zygoapophyseal joints (facet joint arthritis)Any facet joint from C2 to S1 may be involved; usually associated with bone marrow oedema within spinal pedicles (posterior of spinal canal)
Arthritis of costovertebral (CV) jointsAny CV joints from Th1 to Th12 may be involved; associated with bone marrow oedema near CV joint, extending to pedicles, posterior aspect of vertebral bodies (lateral of spinal canal) and neighbouring rib
Enthesitis of spinal ligamentsPossibly affected entheses: supraspinal ligament, interspinal ligaments, ligamenta flava
Syndesmophytes/ankylosisBridging (at the corners of the vertebral bodies) or fusion (new bone formation within the intervertebral disks) occurs in long-standing disease.