Knee Arthrocentesis - Procedure -
Materials: ...

Knee Arthrocentesis - Procedure -


Sterile gloves, chlorhexidine/iodine, 5cc 1-2% lidocaine 5cc w/o Epi (25G needle, 5cc syringe) or ethyl chloride spray, 18-22G needle, 20-60 mL syringe, diagnostic tubes (purple/green top, aerobic/anaerobic bottles), sterile towels/sheet, bandage


Position the knee in extension or 15-20° flexion. Approaches described below:

 • Lateral (see image): 1cm lateral and 1cm superior to the superior 1/3 of the lateral patella. Angle the needle approximately 45° toward the feet and insert behind the patella at a 45° angle to the skin. More likely to yield fluid in difficult cases

 • Medial: 1cm medial to the superior 1/3 of the medial patella. Angle the needle perpendicular to the leg and at a 45° angle to the skin


 • Identify landmarks as above and mark point of entry with the base of a needle cap or pen. Sterilize the site. A sterile field is not technically required but may drape the area w/ a sterile sheet or towels. Prep needles and syringes.

 • Anesthetize overlying skin using ~0.5cc lidocaine (SQ 25G needle, 5cc syringe) to make a wheal. May use remaining lidocaine along procedure tract.

 • Attach 18-20G needle to 30cc syringe and position needle according to approach. Advance needle slowly (avg 1-1.5 in) and aspirate while advancing.

 • Once fluid is visualized, aspirate joint fluid to fill syringe. May attach a 2nd 30cc syringe to drain additional fluid for sx relief pending size of effusion.

 • Withdraw needle and apply bandage. Fill diagnostic tubes (purple OR green top for cell count/diff and crystal eval, aerobic/anaerobic cx bottles).

#Knee #Arthrocentesis #Procedure #instructions #msk #management
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