A simple, accurate method to confirm placement of intra-articular knee injection.
BACKGROUND
Intra-articular knee injections are routinely performed in clinical practice without documenting intra-articular placement.


OBJECTIVE
A small amount of air to an intra-articular knee injection produces an audible "squishing" sound with range of motion.


METHODS
Prospective nonrandomized clinical trial.


METHODS
The study group (20 knees from 20 patients) received an intra-articular injection with a mixture of local anesthetic, corticosteroid, contrast dye, and 1 to 2 cc of air. The control group (10 knees from 5 patients) received extra-articular injections of a mixture of local anesthetic, contrast dye, and 2 cc of air. All knees were examined immediately after injection for a squishing sound with range of motion. Postinjection arthrographic radiographs were taken to verify the actual placement.


RESULTS
All study group knees and no control group knees had intra-articular contrast by radiograph. Clearly audible squishing sounds were heard in 17 of 20 study knees (sensitivity of 85%). Squishing sounds were audible in none of the control knees (specificity of 100%).


CONCLUSIONS
Adding 1 to 2 cc of air to knee injections provides a no-cost, reliable, sensitive, and specific method of confirming accurate placement.


CONCLUSIONS
This simple method is easily reproduced, can confirm accurate placement, and can eliminate extra-articular injection as the reason for clinical response failure.
Glattes
Rudolph C
RC
Department of Orthopaedics and Rehabilitation, Vanderbilt Sports Medicine Center, 2601 Jess Neely Drive, Nashville, TN 37212, USA.
Spindler
Kurt P
KP
Blanchard
Gordon M
GM
Rohmiller
Michael T
MT
McCarty
Eric C
EC
Block
Jake
J
D000388:Air; D006801:Humans; D007270:Injections, Intra-Articular / Q000379:methods*; D007719:Knee Joint; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013016:Sound