creation date: 2026-02-05 21:08
tags: Workups
Inflammatory Arthritis
Background
Inflammatory arthritis refers to a group of arthritis accompanied by features of inflammation (pain, erythema, warmth, swelling, and loss of function).
Pathophysiology
The exact pathophysiology of inflammatory arthritis depends on the underlying etiology.
Generally, an immune-mediated response results in neutrophils, lymphocytes, and macrophage migration from the bloodstream into the synovial membrane. In cases of infection, pathogens may invade the joint space directly while autoimmune pathologies results in immune activation against the synovium.
Differential Diagnosis
Infectious or septic arthritis
Infectious arthritis is typically monomicrobial. Polymicrobial infectious may occur in setting of penetrating trauma.
- Staphylococcus aureus
- Streptococcal pneumoniae
- Neisseria gonorrhea
- Anaerobic bacteria
- Mycobacteria species
- Viruses
Crystalline arthritis
Crystal-induced arthritis due to deposition of crystals in the synovial space:
- Gout (monosodium urate crystals in joint space)
- Pseudogout (caocium pyrophosphate crystal in cartilage)
- Basic calcium phosphate disease
Autoimmune inflammatory arthritis
- Rheumatoid arthritis
- Juvenile idiopathic arthritis
- Seronegative spondyloarthritis (includes psoriatic arthritis, ankylosing spondylitis, reactive arthritis, arthritis associated with IBD, non-radiographic spondyloarthritis)
- SAPHO syndrome (synovitis, acne, pustulosis, hyperostosis, osteitis)
- Arthritis associated with connective tissue or autoimmune diseases
- Systemic lupus erythematosus
- Drug-induced lupus
- Sjorgren syndrome
- Mixed connective tissue disease
- Systemic sclerosis
- Inflammatory myopathies
- Behcet’s disease
- Vasculitis
- Sarcoidosis
- Relapsing polychondritis
- Arthritis associated with malignancy
Initial Evaluation
History
The characteristics of the arthropathy may point towards etiology.
Onset
- Acute - infectious or cystalline
- Subacute or insidious - most autoimmune
Number of joints involved
- Monoarticular - infectious
- Oligoarticular (and mono/polyarticular) - crystalline
- Polyarticular - autoimmune inflammatory (may start mono or oligo)
Prior medical history may suggest infectious arthritis as previously damaged joints can predispose.
Physical Exam
Examination of affected joints should be performed. Note any:
- Tenderness
- Erythema
- Warmth
- Swelling
- ROM limitations
Investigations
Laboratory studies include:
- ESR and CRP (elevated)
- CBC (thrombocytosis and anemia of chronic disease, leukocytosis with infectious arthritis)
- Creatinine and electrolytes
- Serum uric acid (hyperuremia may be present with gout)
- Synovial fluid analysis
Imaging is not typically routine due to lack of specific joint findings.