Monoarticular joint pain swelling warmth erythema, sometimes systemic fever chills, pain for restrictive ROM

1. Synovial fluid aspiration gold standard
2. WBC greater than 50 K with 90% neutrophils (noninflammatory clear yellow WBC< 2000, inflammatory rheumatic autoimmune cloudy WBC 2K-50 K, septic purulent WBC >50 K and hemorrhagic bloody RBC dominant)
3. Gram stain culture positive for organism confirmed the diagnosis
4. Synovial fluid tested for Crystal,  gout or pseudogout can mimic it
5. Blood work ESR CRP WBC count
6. X-ray effusion/nonspecific
7. MRI rule out osteomyelitis

Management

Needle aspiration, arthroscopic lavage or open surgery drainage

IV antibiotic after aspiration before culture result, vanco MRSA coverage plus 3rd generation cephalosporin ceftriaxone if Gram-negative coverage

Pain management

Immobilization initially