Take Home points:

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• Always suspect an open joint if there is a laceration, regardless of size, the lies over joint
  
• CT scan of the affected joint is widely considered to be the standard approach to evaluation but the saline load test may be useful in certain circumstances.
  
• Obtain emergency orthopedics consultation for all open joints and administer antibiotics and update tetanus in all patients
  

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Definition: a deep laceration that extends into the joint capsule, exposing the intra-articular surface to the environment

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• A laceration into the joint exposes the normally sterile intra-articular contents to external contamination
  
• Inoculation of the joint often results in septic arthritis
  

Physical Exam:

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• Laceration over joint (can be variable in size)
  
• Local wound exploration may be sufficient in identifying the open joint
  
• Exam findings suspicious for joint capsule involvement:
  
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    • Air bubbles
      
    • Extravasation of joint fluid – straw colored, viscous, sometimes oily in appearance
      
    
    
    
  
  
  

Diagnostic testing:

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• Imaging:
  
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  • X-ray
    
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    • Limited ability to see air in joints but a reasonable first test
      
    
    
    
  • CT scan
    
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    • Intra-articular air visualized on CT (Konda 2013)
      
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      • May be up to 100% sensitive for joint violation
        
      • Study limited by small numbers, inclusion bias + inadequate gold standard
        
      
      
      
    • May be considered the standard evaluation modality in many settings.
      
    
    
    
  
  
  

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• Saline load test
  
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  • Has mainly been supplanted by CT scan due to ease in obtaining, reported performance characteristics, consultant recommendation and difficulty in interpreting test.
    
  • Useful if physical examination equivocal or plain radiographs non-diagnostic
    
  • Technique (Video)
    
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    • Perform arthrocentesis of the joint with a large bore needle (18-20 gauge)
      
    • Sterile saline is injected into the joint while passive movement is applied to the joint
      
    • The laceration site is watched for saline extravasation indicating communication between the joint and external environment
      
    
    
    
  
  
  

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  • Sensitivity ranges from 34%-99% depending on the study, joint, and the amount of saline used to load the joint (Browning 2016)
    
  • Methylene blue
    
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    • Aids in distinguishing a true positive from additional bleeding from the wound
      
    • Recent studies suggest that the addition of methylene blue does not increase sensitivity if a sufficient amount of saline is used (Metzger 2012)
      
    
    
    
  • Volume of fluid injected
    
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    • Varies depending on the joint in which you are injecting
      
    • Higher volumes increase sensitivity but also increase pain for the patient
      
    • Knee Joint (Keese 2007)
      
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      • 50 ml: Sensitivity of about 46%
        
      • 194 ml: sensitivity of 95%
        
      
      
      
    • Elbow Joint (Feathers 2011)
      
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      • 20 ml: Sensitivity of 86%
        
      • 40 ml: Sensitivity of 95%
        
      
      
      
    • Ankle Joint (Bariteau 2013)
      
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      • 7 ml: Sensitivity of 50%
        
      • 30 ml: Sensitivity of 95%
        
      
      
      
    
    
    
  
  
  

ED Management:

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• Reduce open fractures if present
  
• Irrigate grossly contaminated wounds in the ED
  
• Immobilize the joint to prevent further injury
  
• Obtain early orthopedic evaluation for joint exploration, and washout to be performed within 6-24 hours
  
• Tetanus prophylaxis
  
• Prophylactic antibiotics (best if given within 6 hours)
  
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  • Staph/strep coverage: 1^st generation cephalosporin (i.e. cefazolin or cefuroxime)
    
  • If risk factors for MRSA present, use agent with activity against MRSA (i.e. vancomycin)
    
  • If significant soft tissue injury, add gram negative coverage like late generation cephalosporin, extended-spectrum penicillin, or aminoglycoside (i.e. gentamycin)
    
  • If concern for fecal or clostridial infection, add high dose penicillin (i.e. zosyn)
    
  • If seawater contamination and concern for vibrio vulnificus, add doxycycline
    
  
  
  

Post Peer Reviewed By: Salim R. Rezaie, MD (Twitter/X: @srrezaie)

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