Rosen & Barkin's 5-Minute Emergency Medicine Consult (75 page)

• Blood testing never the key diagnostic studies of choice for monoarticular arthritis; provides ancillary, corroborative, exclusionary information.
  
• Arthrocentesis for synovial fluid aspiration and analysis the definitive diagnostic procedure and studies.
  
• Synovial fluid culture the definitive synovial study regarding infection, but results not immediate (inherent nature of the test)
  
• Fluid appearance: Clear versus turbid, serous versus bloody, viscosity (“string sign”), volume removed, associated pain (levels, trends)
  
• Synovial fluid white blood cells (WBC), polymorphonuclear (PMN) predominance suggests septic etiology
  
  • WBC >50,000/mm
    ³
    increases likelihood of septic arthritis
    
• Synovial glucose: Most useful compared to concurrent blood glucose levels
  
  • Synovial glucose less than half blood value indicates likely septic process
    
• Gram stain (positive stain)
  : Directs initial antibiotic selection, administration
  
  • Gram + cocci: Vancomycin
    
  • Gram – cocci: Ceftriaxone
    
  • Gram – rods: Ceftazidime
    
• Gram stain (negative stain):
  Clinical suspicion for septic joint: Empiric vancomycin + ceftazidime or aminoglycoside
  
• Viscosity: “String sign”
  
  • Slowly drip fluid off needle or syringe, noting the length of the “stringing.”
    
  • Noninflammatory fluid has longer strings
    
  • Inflammatory fluid will drip like water
    
• Crystal analysis: Polarized light microscopy for birefringent crystals: Gout (negative), pseudogout (positive)
  
• Rheumatologic “screening panel” for suspected disease: Uric acid, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), rheumatoid factor (RF), anticyclic citrullinated peptide (ACCP)
  
• Lyme testing (anti-
  Borrelia
  titers or “Lyme titers”) for monoarticular arthritis presenting in endemic areas
  
• Fat globules in bloody aspirate: Suspect fracture with marrow (fat globules), synovial space communication
  

• Plain films
  reasonable cost-effective choice:
  
  • Joint surfaces: Chondral, subchondral erosions, joint margin destruction or reactive bone formation (osteophytes, “spurring”), loose bodies, fractures
    
  • Infectious
    : As above plus soft-tissue swelling, joint capsule distortion
    
  • Crystalline:
    As above plus soft-tissue calcification, tophi usually located on or near frequent, repetitive joint flares
    
• Ultrasound:
  Detects joint fluid, tissue and vascular perfusion, periarticular structures, foreign bodies (especially if small, superficial organic composition of tissue density)
  
  • Guides aspiration attempts
    
• MRI
  detects bone necrosis, subtle fractures
  
• Bone or gallium scans do not distinguish Infectious versus inflammatory, especially chronic
  

See “Diagnostic Tests & Interpretation” above.

• Arthrocentesis for synovial fluid aspiration, analysis the definitive diagnostic procedure and laboratory studies.
  

See “Etiology” and “Signs and Symptoms” “Pediatric
Considerations” above.

TREATMENT

Alluding to subsequent headings containing all pertinent consideration.

• Joint immobilization, position of comfort
  
• Vascular access for rapid, titratable, predictable medication effects
  
• Symptom control: Pain, nausea, vomiting, fluid replenishment
  
• Joint aspiration as soon as practicable; analysis directs therapy, disposition
  

• See “Diagnostic Procedures” above
  
• Septic arthritis:
  
  • Urgent empiric IV bactericidal antibiotics: Ceftriaxone, vancomycin for
    Staphylococcus, Streptococcus,
    gonococcal arthritis
    
  • Subsequent outpatient antibiotics (PICC line, oral) therapy duration variable, multifactorial: Joint involved, organism, underlying health, patient compliance, medical costs
    
  • Surgical irrigation considerations (“washouts”): Joint involved, open versus closed, single versus multiple sequential, comorbid conditions, patient compliance, medical costs
    
• Crystalline:
  
  • Treatment goals: (1) Quell the acute flare: NSAIDs (indomethacin, naproxen), colchicine, steroids; (2) only after acute exacerbation quelled:
    
    • Prophylaxis with flare prevention medications (colchicine, naproxen), begin urate-lowering therapy (allopurinol, febuxostat)
      
  • Febuxostat as effective or greater than allopurinol for gout flares, tophus area, uric acid levels.
    
  • Probenecid: Efficacious long-term uricosuric, alone or in conjunction with allopurinol
    
• Noninflammatory
  :
  
  • NSAIDs, analgesics
    
  • Physical therapy, rehabilitation
    
  • Orthopedic trauma: Immobilize, pain control, ensure neurovascular status intact
    
  • Hemorrhagic causes: Correction of factor levels, component replacement
    

FOLLOW-UP

• Unable to perform ADL
  
• Evidence systemic illness, metabolic derangement (sepsis, DKA)
  
• Any joint requiring surgical intervention (including serial washouts)
  
• Intractable pain
  
• All septic arthritis
  
  • General medical/surgical bed
    
  • Intensive care unit if generalized sepsis, metabolic derangement
    
• Crystalline:
  
  • Intractable nausea, vomiting, diarrhea
    
  • Septic joint superimposed on other arthritis
    

• Symptoms (including pain) controlled, comorbid conditions stable, managed appropriately
  
• Medication compliance: Can obtain medications (economically, logistically), understands dosages, time intervals.
  
• Timely follow-up possible
  

Immediate consultation, admission for infectious etiologies, intractable pain, poorly controlled comorbid illnesses, interference with ADL

• As soon as practicable, with health care providers best suited, capable of treating the condition in question.
  
• If unable to acquire the appropriate care in a timely manner, return to ED (safety net).
  

• Joint aspiration with Gram stain of fluid is the most important aspect of securing a diagnosis, directing initial management
  
• Suspect septic arthritis in the presence of Intra-articular corticosteroid administration, diabetes, drug abuse, trauma, injections through cellulitis and extra-articular infection
  

• Carpenter CR, Schuur JD, Everett WW, et al. Evidence-based diagnostics: Adult septic arthritis.
  Acad Emerg Med
  . 2011;18(8):781–796.
  
• Genes N, Chisolm-Straker M. Monoarticular arthritis update: Current evidence for diagnosis and treatment in the emergency department.
  Emerg Med Pract
  . 2012;14(5):1–19.
  
• Smith BG, Cruz AI Jr, Milewski MD, et al. Lyme disease and the orthopaedic implications of Lyme arthritis.
  J Am Acad Orthop Surg
  . 2011;19(2):91–100.
  

CODES

• 274.00 Gouty arthropathy, unspecified
  
• 711.90 Unspecified infective arthritis, site unspecified
  
• 716.90 Arthropathy, unspecified, site unspecified
  

BASICS

• Chronic systemic inflammatory disorder that attacks the joints:
  
  • Nonsuppurative, proliferative synovitis
    
  • Destruction of the articular cartilage
    
  • Ankylosis of the joint
    
• Involvement of knee is common.
  
• Baker cysts may be seen in chronic disease.
  
• Involvement of spine is limited to cervical region:
  
  • May cause atlantoaxial subluxation
    
  • Rarely results in cord compression
    

Juvenile rheumatoid arthritis (JRA) is a distinct entity (see “Arthritis, Juvenile Idiopathic”).

• Genetics:
  
  • Genetic predisposition related to HLA-DR4
    
  • Female-to-male ratio is 3:1.
    
  • Typical age of onset is between 30 and 50.
    

• Etiology is unknown.
  
• Possible triggers include infection and autoimmune response.
  
• Prevalence is about 1% of both US and world population.
  

DIAGNOSIS