Arthritis - rheumatoid
Description
- Chronic symmetrical inflammatory polyarthritis of synovial joints, erosive and deforming if untreated
- Systemic disease with extra-articular manifestations - joints are the commonest, not the only, target
Serological subsets
| Anti-CCP / RF | Features | |
|---|---|---|
| Seropositive (~70%) | Positive | Erosive, extra-articular disease, nodules, worse prognosis, HLA-DRB1 shared epitope |
| Seronegative (~30%) | Negative | Less erosive on average; overlaps with PsA, PMR, CPPD - re-examine the diagnosis |
Joint distribution - the discriminator
- MCP, PIP, wrists, MTPs - symmetrical, small-joint
- *DIP joints spared (DIP involvement = PsA or OA*)
- Cervical spine involved (C1/2 atlanto-axial); thoracolumbar spine and SI joints spared
Established deformities
- Ulnar deviation at MCPs, Z-thumb
- Swan-neck - PIP hyperextension + DIP flexion
- Boutonniere - PIP flexion + DIP hyperextension
- Subluxation, carpal collapse, fixed flexion contracture
- Deformity is fixed - contrast Jaccoud's arthropathy of SLE, which reduces on making a fist
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