AS

Question 1

Radiographic Fx- SIJ

Answer 1

Hallmark involvement of AS

Optimal projection is angulated spot view.

Earliest sign may be subtle widening of SI jnt space.

Question 2

Radiographic Fx- SIJ / General

Answer 2

Bilateral and symmetric

Iliac side more extensively involved

Initially involves lower two thirds of joint.

Question 3

Radiographic Fx- SIJ / Early

Answer 3

Articular erosions (rosary beads)

Diminished joint space

Loss of articular cortex definition (Pseudowidening)

Patchy reactive sclerosis

Subchondral osteoporosis

Question 4

Radiographic Fx- SIJ / Late

Answer 4

Bony ankylosis

Generalised osteoporosis-disappearance of reactive sclerosis

Ghost joint margin (visualization of articular cortex through ankylosed joint)

Star sign: ossification of superior sacroiliac ligs, creating triangular radio opacity.

Question 5

Radiographic Fx- Discovertebral

Answer 5

Syndesmophytes formation, inflammation, destruction and lig ossification

Starts with annulus enthesis as a lytic vertebral body rim lesion.

Rommanus lesion – lucent corner erosion.

Creates squared contour. Repair may actually create a convex margin “barrel shaped vertebrae”.

Shiny corner sign -Erosions heal with transient sclerosis

Marginal syndesmophytes- fine vertical bridging ossifications at outer disc, originating at adjacent vertebral body margins.

Bamboo spine- Multiple ankylosed vertebrae

Trolley track appearance- d/t facet jt fusion