42 year old M presents with R knee pain, no PMH, c/o subjective fevers at home but no other associated symptoms.
On exam vitals signs stable except temperature of 100.4, also found to have tenderness to palpation, mild erythema, and significant swelling to knee. Able to range about 20 degrees. No other affected joint.
Concern for a septic joint.
To build off of Dr. Bell’s septic arthritis pearl, on this busy Monday we will keep it short but sweet with a quick refresher on knee arthrocentesis.
Diagnosis of septic or crystal induced arthritis
Administration of medications or analgesia for acute or chronic arthritis
Relief of pain of acute hemarthrosis
Determination of laceration communicating with joint space
Overlying cellulitis (absolute)
Bleeding diathesis (relative)
Landmark – medial or lateral patella, superior/middle portion; approach may be lateral or medial
Position your patient with knee flexed about 15 degrees in order to open the joint space, prop up knee with pillows or sheets
Insert your 18 gauge needle at the mid to superior region of the medial (or lateral) patella, direct your needle under the patella and between the femoral intercondylar notch, as much as possible keep needle parallel to bed, aspirate while inserting needle until you observe synovial fluid in your syringe.
Of note, for those of you who prefer movies, there are a plethora of youtube videos that will aid in your knee tapping education.
Clinical Procedures in Emergency Medicine. 5th ed.
Roberts, James R.; Hedges, Jerris R. (2010)