Stony Brook
EMergency Medicine

(631) 444-3880


101 Nicolls Road,

Stony Brook, NY 11794

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Copyright 2019 Designed by Michael Beck MD

The Best in FOAM Education

How To Do It: Arthrocentesis

August 17, 2019

Should You?



  • Suspicion of septic arthritis

  • Suspicion of crystal induced arthritis

  • Evaluating if laceration violated joint space

  • *Therapeutic (to relieve pressure or inject steroid/anesthetic)


(Relative) Contraindications:

  • Overlying infection

  • Coagulopathy

  • Hardware 



  • Septic arthritis 1/3000 - 1/10000

  • Tendon rupture

  • Post injection flare - 5% - chemical inflammation from crystals in steroid solution (different from septic arthritis because it is fast onset and resolves within 48 hours)

  • Facial flushing - 10% - starts w/i hours and resolves within days

  • Maybe cartilage damage with repeated injections

  • Hyperglycemia / steroid systemic issues


Could you?


What do you need:

  • Chlorhexidine

  • Sterile gauze/ sterile drape/ OR towels to create a sterile field

  • Lidocaine (with syringe and needles for local)

  • Large syringe for aspiration (20cc or 60cc syringe)

  • Needles 18g (knee), 20g (wrist/ankle/elbow), 25g (fingers)

  • Specimen cup


If you wanna inject:

  • 3 way stopcock (or you can just switch out your syringe before injection)

  • Syringe 

    • 10cc for knee and shoulder

    • 5cc for elbow and ankle

    • 2cc for wrist

  • Lidocaine

  • Triamcinolone

    • 40mg knee/shoulder

    • 30mg for elbow/ankle

    • 20mg for wrist 

  • Fill your syringe with the steroid (1 cc) and lidocaine (or anesthetic of choice) for the rest of desired volume


What’s your approach?

  • Knee placed ~15-20 degrees flexion- towel underneath

  • Parapatellar approach

    • Medial or lateral to the midpoint

  • Suprapatellar approach

    • Medial or lateral from superior third border

  • Direct needle under the patella towards the intercondylar notch while maintaining negative pressure on the syringe

  • Can milk the bursa to increase yield of tap

  • When done aspirating, twist your 3 way stopcock (or replace aspiration syringe with medication syringe) and inject the joint space - should be low resistance

  • Bandaid or bandage around joint to keep it clean

  • Send the fluid for analysis


Would You?

  • 4 weeks to 26 weeks depending on study

  • Steroids are beneficial in inflammatory conditions such as rheumatoid arthritis

  • Can also help in osteoarthritis

  • Steroid injections should not be given in suspected septic arthritis



Arman Sobhani, MD is a current third year resident at Stony Brook Emergency Medicine.




Edited by Bassam Zahid, MD

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