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Imaging of joint disease and metabolic bone disease

On radiographs inflammatory arthritis (periarticular osteopenia, marginal erosions, symmetric narrowing) is distinguished from degenerative disease (osteophytes, sclerosis, asymmetric narrowing), and the distribution of joints in the hand identifies RA, osteoarthritis, psoriatic arthritis, gout and CPPD.

לקריאה בעברית

Why it matters in the exam

RA: periarticular osteopenia, symmetric narrowing, marginal erosions ("bare areas") at the MCP, PIP, wrist and ulnar styloid; the DIP joints are spared and there is no new bone formation. In the cervical spine — atlantoaxial subluxation. Pannus is thickened inflamed synovium. Osteoarthritis: asymmetric narrowing, sclerosis, subchondral cysts and osteophytes; in the hand DIP, PIP and the base of the thumb (first CMC) — not MCP. Erosive osteoarthritis — central "gull-wing" erosions. Psoriatic arthritis: DIP erosions with new bone formation, "pencil-in-cup", periostitis and a "sausage" digit, asymmetric. Gout: "punched-out" erosions with overhanging edges, joint space preserved until late, tophi; DECT shows urate deposits. CPPD: chondrocalcinosis in the menisci, the wrist TFCC and the symphysis; "hook" osteophytes at MCP 2–3 point to haemochromatosis.

Axial spondyloarthritis: bilateral symmetric sacroiliitis — erosions, sclerosis and later fusion. MRI on STIR shows subchondral bone marrow oedema = active sacroiliitis, long before the radiograph changes. In the spine: thin vertical syndesmophytes, "shiny corners" (Romanus) and finally a "bamboo spine". DISH: "flowing" ossification along the anterior right side of at least 4 contiguous vertebrae in the thoracic spine, with preserved disc height and without sacroiliitis. Osteitis condensans ilii — triangular sclerosis on the iliac side in a woman who has given birth, with the joint itself normal.

Metabolic bone: hyperparathyroidism — subperiosteal resorption on the radial side of the middle phalanges of fingers 2–3, tuft resorption, brown tumours, a "salt-and-pepper" skull, and resorption on the iliac side of the sacroiliac joint that widens it; a "rugger-jersey" spine in renal failure. Rickets: wide, "cupped" and frayed metaphyses and a wide growth plate. Osteoporosis: a thin cortex and prominence of the vertical trabeculae. Paget disease: bone enlargement, a thick cortex and coarse trabeculae; in the lytic phase — a "blade of grass" front. PVNS — synovium with haemosiderin that is dark and blooms on gradient echo, usually in the knee. Joint fluid with internal echoes on US — pus, blood, crystals or fibrin; with suspected septic arthritis — immediate aspiration.

Key points

• RA — marginal, symmetric, no new bone.
• Osteoarthritis — osteophytes, DIP and first CMC.
• Psoriatic arthritis — DIP, pencil-in-cup.
• Early sacroiliitis — STIR MRI.
• Hyperparathyroidism — radial subperiosteal resorption.

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Sources

• ASAS Classification Criteria for Axial Spondyloarthritis (and 2019 MRI update), 2009, updated 2019 — Active sacroiliitis on MRI
• EULAR Recommendations for the Use of Imaging in the Diagnosis and Management of Spondyloarthritis, 2015 — Radiography and MRI
• EULAR Recommendations for the Use of Imaging in Crystal-Induced Arthropathies, 2023 — US and DECT

Sources are given for further reading; the text is written afresh and not copied from them.

Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.