Symmetric small-joint disease with periarticular osteopenia, uniform joint space loss and marginal erosions; ultrasound and MRI show synovitis and erosions years before the radiograph — and atlantoaxial instability must be looked for before anaesthesia.
Orient first
- Early sites: MCP 2–3, PIP, ulnar styloid, MTP 5.
- Erosions start at the bare areas (marginal) — no bone production (unlike psoriatic arthritis).
- Cervical spine: atlantoaxial subluxation (ADI > 3 mm in adults — verify), basilar invagination, subaxial subluxation.
Acquire the study
- PA and oblique radiographs of both hands and both feet.
The manoeuvre
- Radiograph: periarticular osteopenia; symmetric joint space narrowing.
- Marginal erosions at MCP 2–3, ulnar styloid, MTP 5 (the earliest foot site).
- Deformities: ulnar deviation, swan neck, boutonnière.
- Cervical flexion radiograph: atlantodental interval in mm.
What confirms it
- Symmetric small-joint erosive arthritis with serology (RF/anti-CCP) and clinical criteria.
What licenses you to exclude it
- Normal ultrasound without synovitis makes active inflammatory arthritis unlikely.
The classic misread
- Calling erosive osteoarthritis (central erosions, gull-wing) RA.