Wk 3 Dx Imaging

Q: Are the radiographic features of extremity DJD the same as spinal DJD?

A: Yes — non-uniform joint space narrowing, osteophytes, subchondral sclerosis, and subchondral cysts all apply to peripheral joints.

Q: What is the Rosenberg view and why is it used?

A: A weight-bearing PA knee view at ~45 degrees flexion more sensitive than a standard extended view for detecting early posterior joint space narrowing in knee OA.

Q: What is juxta-articular osteoporosis and why does it occur in RA?

A: Osteoporosis adjacent to RA-affected joints, caused by hyperaemia increasing bone turnover.

Q: Which carpal joints does RA typically affect first?

A: The carpals up to and including the first CMC joint PIPs and DIPs are typically spared unless disease is advanced.

Q: What is the Ball Catcher's view used for?

A: A PA hand/wrist projection (hands as if catching a ball) that profiles the metacarpal heads and proximal joint margins useful for detecting early RA erosions.

Q: Describe the Boutonniere deformity.

A: PIP joint hyperflexion with DIP hyperextension seen in advanced RA.

Q: Describe the Swan-neck deformity.

A: PIP joint hyperextension with DIP flexion seen in advanced RA.

Q: What is ulnar deviation?

A: Deviation of the fingers toward the ulnar side at the MCP/CMC joints classically seen in advanced RA.

Q: What is arthritis mutilans?

A: Severe destructive arthritis causing bone resorption and "telescoping" of digits can occur in any form of erosive arthritis, not just RA.

Q: What is fibular deviation of the MTP joints?

A: Lateral angulation at the metatarsophalangeal joints — the foot equivalent of ulnar deviation seen in RA.

Q: What is protrusio acetabuli and how is it assessed?

A: Medial migration of the femoral head through the acetabulum (advanced RA) assessed by a line from the lateral sciatic notch to the obturator foramen — femoral head crossing medially = protrusio.

Q: Why are horizontal beam radiographs used at the knee in suspected RA?

A: To detect a joint effusion — a fluid level is only visible using a horizontal X-ray beam.

Q: What is the end-stage outcome of RA joint disease?

A: Complete bony ankylosis.

Q: What vascular finding can be seen on RA imaging?

A: Calcified venous thrombi.

Q: What is phalangeal sclerosis and in which condition is it seen?

A: Increased density/thickening of the distal phalanx seen in RA.

Q: How is Erosive Osteoarthritis (EOA) classified relative to typical OA?

A: A non-serological, inflammatory variant of OA.

Q: Who is typically affected by EOA and which joints?

A: Women in the 4th-5th decade affects DIPs, PIPs, and the base of the thumb (1st CMC joint).

Q: What deformity distinguishes EOA from typical nodal OA?

A: The "gull-wing" deformity — a central joint erosion flanked by marginal osteophytes producing a gull-wing shaped articular contour.

Q: What key radiographic feature differentiates PsA from RA at bone adjacent to joints?

A: PsA shows NORMAL bone mineralisation — NO juxta-articular osteoporosis (unlike RA).

Q: Which joints/regions does PsA typically target?

A: Small joints of the hands/feet (especially DIPs), SIJ, and the spine larger joints less commonly.

Q: What is the distribution pattern of PsA compared to RA?

A: PsA is asymmetrical RA is symmetrical. PsA shows NO ulnar deviation.

Q: What are "mouse ears" in PsA?

A: Marginal erosions accompanied by periostitis — a descriptive term for the appearance in PsA.

Q: What are "sausage digits" (dactylitis)?

A: Diffuse swelling of an entire digit from soft tissue oedema seen in PsA.

Q: Describe the pencil-in-cup deformity.

A: Progressive tapering ("whittling") of an entire bone due to erosion, articulating with a cupped, expanded base of the adjacent bone.

Q: What is the ray pattern in PsA?

A: All joints of a single digit (DIP to MCP) are simultaneously affected.

Q: What is the opera-glass hand deformity?

A: Phalanges destroyed and telescoping into themselves only seen in severe cases of arthritis mutilans.

Q: What is the SIJ involvement pattern in PsA?

A: ~50% have SIJ involvement bilateral but ASYMMETRICAL (unlike AS which is bilateral and symmetrical).

Q: What are non-marginal syndesmophytes in PsA?

A: "Floating" ossifications that do NOT connect to the adjacent endplate (most common in PsA) contrasts with the marginal syndesmophytes of AS.

Q: What is acro-osteolysis?

A: Bone destruction/resorption at the tip of a digit (fingertip resorption).

Q: What is an ivory phalanx?

A: A markedly increased density (radio-opaque) phalanx a specific but less common finding in PsA.

Q: What skin findings are characteristic of PsA?

A: Well-defined, dry, raised, red, silvery scaly lesions on extensor surfaces (knees, elbows, back) 80% of PsA patients have nail changes.

Q: How does pannus in PsA differ from pannus in RA?

A: In PsA, pannus affects cartilage less aggressively erosions are smaller/slower, with characteristic "fluffy" new bone forming adjacent to erosions.