Arthritis

Background

• Arthritis refers to joint inflammation, characterized by pain, swelling, warmth, and decreased range of motion
• The primary EM concern is ruling out septic arthritis, which is a joint emergency requiring urgent drainage
• Classification by number of joints involved helps narrow the differential:
  • Monoarticular (1 joint): septic arthritis, crystal disease, hemarthrosis — see Monoarticular arthritis
  • Oligoarticular (2-4 joints): reactive arthritis, seronegative spondyloarthropathy, gonococcal arthritis
  • Polyarticular (≥5 joints): rheumatoid arthritis, viral arthritis, SLE, rheumatic fever
  • Migratory: rheumatic fever, gonococcal arthritis, viral
• Key distinction: inflammatory (warm, swollen, worse with rest, morning stiffness >30 min) vs. non-inflammatory/mechanical (worse with activity, minimal swelling, no morning stiffness)

Clinical Features

History

• Number and pattern of joints involved
• Acute vs. chronic onset
• Symmetric vs. asymmetric distribution
• Morning stiffness: >30-60 minutes suggests inflammatory arthritis
• Recent infection: pharyngitis (post-strep/rheumatic fever), GI illness (reactive arthritis), STI (gonococcal)
• Skin findings: rash, psoriasis, tophi, dermatitis-arthritis syndrome
• Eye symptoms: conjunctivitis (reactive arthritis), uveitis (ankylosing spondylitis)
• Trauma history
• Family history of autoimmune disease
• Medication history: diuretics, cyclosporine (gout risk)

Physical Exam

• Joint warmth, swelling, effusion, tenderness
• Range of motion (active and passive)
• Pain with passive ROM suggests intra-articular pathology
• Periarticular tenderness without effusion suggests bursitis/tendinitis (periarticular, not articular)
• Skin: tophi (gout), dactylitis (psoriatic arthritis), rash, nail pitting (psoriasis)
• Mucocutaneous lesions (gonococcal — pustules on palms/soles, tenosynovitis)
• Heart murmur (endocarditis, rheumatic fever)

Red Flags

• Hot, swollen, single joint = septic until proven otherwise → arthrocentesis
• Fever with joint complaints (septic arthritis, endocarditis)
• Prosthetic joint with new pain/swelling (prosthetic joint infection)
• IV drug use + joint pain (hematogenous seeding)
• Polyarthritis + new murmur (endocarditis)
• Pediatric arthritis + fever + rash (consider Kawasaki disease, rheumatic fever, JIA)

Differential Diagnosis

Monoarticular arthritis

Algorithm for Monoarticular arthralgia

• Acute osteoarthritis
• Avascular necrosis
• Crystal-induced (Gout, Pseudogout)
• Gonococcal arthritis, arthritis-dermatitis syndrome
• Nongonococcal septic arthritis
• Lyme disease
• Malignancy (metastases, osteochondroma, osteoid osteoma)
• Reactive poststreptococcal arthritis
• Trauma-induced arthritis
  • Fracture
  • Ligamentous injury
  • Overuse
• Avascular necrosis
• Decompression sickness
• Spontaneous osteonecrosis
• Hemorrhagic (e.g. hemophilia, systemic anticoagulation
• Seronegative spondyloarthropathies (ankylosing spondylitis, IBD, psoriatic arthritis, reactive arthritis
• RA, SLE
• Sarcoidosis, amyloidosis
• Periarticular pathology
  • Cellulitis
  • Tendonitis
  • Bursitis
• Transient (Toxic) Synovitis (Hip)
• Slipped Capital Femoral Epiphysis (SCFE)
• Legg Calve Perthes Disease

Oligoarthritis

• Ankylosing spondylitis
• Gonococcal arthritis
• Lyme disease
• Psoriatic arthritis
• Reactive arthritis
• Rheumatic fever
• Rheumatoid arthritis
• Systemic lupus erythematosus

Polyarthritis

Algorithm for Polyarticular arthralgia

• Fibromyalgia
• Juvenile idiopathic arthritis
• Lyme disease
• Osteoarthritis
• Psoriatic arthritis
• Reactive poststreptococcal arthritis
• Rheumatoid arthritis
• Rheumatic fever
• Serum sickness
• Systemic lupus erythematosus
• Serum sickness–like reactions
• Viral arthritis

Migratory Arthritis

• Gonococcal arthritis
• Lyme disease
• Rheumatic fever
• Systemic lupus erythematosus
• Viral arthritis

Evaluation

Monoarticular (Most Critical Workup)

• Arthrocentesis — perform on any acute hot, swollen joint
  • Synovial fluid: cell count, Gram stain, culture, crystal analysis
  • WBC >50,000 with >90% PMNs = presumed septic until culture results
  • Crystals: negatively birefringent (gout), positively birefringent (pseudogout)
  • Note: crystals do NOT rule out co-existing infection — always send cultures
• Blood cultures
• CBC, ESR, CRP
• Uric acid (may be normal during acute gout flare)
• X-ray of affected joint

Polyarticular

• CBC, BMP, ESR, CRP
• Rheumatoid factor, anti-CCP (rheumatoid arthritis)
• ANA (SLE)
• GC/CT NAAT, blood cultures if infectious etiology suspected
• Hepatitis B/C, parvovirus B19 serologies if viral arthritis suspected
• ASO titer if rheumatic fever suspected
• X-rays of affected joints
• Consider echocardiography if endocarditis suspected

Management

Septic Arthritis

• Emergent orthopedic consultation for drainage
• Empiric IV antibiotics: vancomycin +/- ceftriaxone (see Septic arthritis)

Crystal Arthropathy

• NSAIDs (indomethacin, naproxen), colchicine, or corticosteroids
• Intra-articular steroid injection after ruling out infection
• See Gout, Pseudogout

Inflammatory/Autoimmune

• NSAIDs for symptomatic relief
• Rheumatology consultation/referral
• Specific management depends on underlying diagnosis

Gonococcal Arthritis

• Ceftriaxone + treat for chlamydia co-infection
• See Gonococcal arthritis

Disposition

Admit

• Septic arthritis (for surgical drainage and IV antibiotics)
• Prosthetic joint infection
• Endocarditis
• Severe systemic inflammatory process
• New rheumatic fever

Discharge

• Crystal arthropathy with adequate pain control
• Viral arthritis
• Known autoimmune arthritis with mild flare
• Arrange rheumatology follow-up for new polyarthritis
• Return precautions: fever, worsening joint swelling, new joint involvement, inability to bear weight

See Also

• Monoarticular arthritis
• Septic arthritis
• Arthrocentesis
• Gout
• Pseudogout
• Rheumatoid arthritis
• Gonococcal arthritis