Pathology: A multi-systemic autoimmune disorder, rheumatoid arthritis affects synovial joint membranes causing inflammation with swelling, tenderness, warmth, and decreased range of motion. Stiffness is often worst in the morning and improved with movement.
Aetiology: HLA-DR4 is found in 60% of rheumatoid arthritis (RA) patients, and T cells activate macrophages leading to production of pro-inflammatory cytokines, such as tumour necrosis factor-_ (TNF-_) and interleukin-1 (IL-1). In addition, B cells release various antibodies, including rheumatoid factor and anti-cyclic citrullinated peptide (anti-CCP).
Symptoms: Aside from joint inflammation, patients also suffer from malaise and fatigue.
Signs: Patients typically present with persistent symmetrical polyarthritis, rheumatoid nodules, lymphadenopathy, pericarditis, pericardial effusion, vasculitis, pulmonary fibrosis, swan neck deformity (PIP hyperextension and DIP flexion due to volar plate damage), boutonniere deformity (PIP flexion and DIP hyperextension), Z-thumb deformity (PIP hyperextension with flexion and MCP subluxation), and ulnar deviation (deviation at the fingers).
Investigations: Blood tests can reveal raised erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), as well as a positive rheumatoid factor and anti-CCP, while imaging, such as X-rays of the joints, MRI or ultrasound scan, can assess for erosion. Joint aspiration can also reveal a raised white cell count and protein.
Treatment: Treatment of rheumatoid arthritis includes conservative management, such as exercise, diet, counselling, and physiotherapy, as well as medical intervention with non-steroidal anti-inflammatory drugs (NSAIDs), steroids, disease-modifying anti-rheumatic drugs (DMARDs), such as sulfasalazine, methotrexate, or azathioprine, and, if DMARDs fail, biological therapy with tumour necrosis factor inhibitors (e.g. adalimumab) or immunomodulators (e.g. rituximab). Surgery may also be required, such as synovectomy, reconstruction, arthroplasty, and arthrodesis.
Complications: Rheumatoid arthritis can cause cardiovascular complications, such as endocarditis, myocarditis, and pericarditis, as well as eye problems, such as episcleritis, scleritis, and keratoconjunctivtis, neurologic complications, such as peripheral neuropathy, respiratory problems, such as nodules, pleural effusion, and fibrosing alveolitis, Caplan's syndrome in coal miners with pneumoconiosis, Felty's syndrome (positive rheumatoid factor, splenomegaly, and neutropenia), and Still's disease (juvenile arthritis, fever, and rash).
Figure 8.1 Signs of Rheumatoid Arthritis
Prognosis: Systemic involvement is a poor prognostic factor for rheumatoid arthritis, as it can lead to further complications of the condition.
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