Indications

• 
  

  • Diagnostic: Sampling of fluid for laboratory evaluation (eg, septic joint, inflammatory arthritis).

  
  

  • Therapeutic.

  
  
  
  
  • 
    

    • Injection of corticosteroids.

    
    

    • Injection of local anesthetic.

    
    

    • Removal of hemarthrosis for pain relief following trauma.

Contraindications

Absolute

• 
  

  • Skin or soft tissue infection (eg, cellulitis, septic bursitis) because there is an increased risk of causing a septic joint.

  
  

  • Corticosteroid injection into a known or suspected septic joint.

Relative

• 
  

  • Coagulopathy. The procedure may result in hemarthrosis, but one needs to weigh the risk against the need to diagnose a septic joint.

  
  

  • Bacteremia, because of the increased risk of causing septic joint.

Equipment

• 
  

  • Syringes (20 mL for knee; 10 mL for ankle).

  
  

  • 21–25-gauge needles; they must be long enough to enter joint.

  
  

  • Sterile collection container.

  
  

  • Povidone-iodine and alcohol for sterile preparation of skin.

  
  

  • Sterile gloves.

  
  

  • 4 × 4 gauze.

  
  

  • Ethyl chloride (optional).

  
  

  • Lidocaine (optional).

Risks

• 
  

  • Infection occurs in < 1/10,000 when performed under sterile conditions.

  
  

  • Bleeding into joint is exceedingly rare, even in patients who are taking anticoagulant medication.

  
  

  • If corticosteroids are being injected, there is a risk of skin discoloration and fat atrophy following the procedure.

Pearls and Tips

• 
  

  • Do not make an ink mark directly over injection/aspiration site because it will enter the joint when the needle passes through it.

  
  

  • Instead, use the wood end of a sterile cotton swab or another round object to make an indentation in the skin prior to cleaning with povidone-iodine.

  
  

  • If infection is a concern, a larger bore needle (18 gauge or 19 gauge) may be needed to aspirate because sometimes purulent fluid will not be drawn into a smaller needle.

  
  

  • Do not overtighten the needle on to the syringe, and check to make sure the needle easily twists off the syringe before starting the procedure.

  
  

  • This allows you to empty a full syringe and reattach it without ever pulling the needle out of the joint.

  
  

  • Lidocaine can be used to numb the skin prior to aspiration/injection, but it can distort anatomic landmarks.

  
  

  • Alternatively, a topical agent such as ethyl chloride can be used.