title: A simple, accurate method to confirm placement of intra-articular knee injection.
abstract: 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.
authors.affiliation: Department of Orthopaedics and Rehabilitation, Vanderbilt Sports Medicine Center, 2601 Jess Neely Drive, Nashville, TN 37212, USA.
authors.forename: Rudolph C
authors.initials: RC
authors.lastname: Glattes
authors.forename: Kurt P
authors.initials: KP
authors.lastname: Spindler
authors.forename: Gordon M
authors.initials: GM
authors.lastname: Blanchard
authors.forename: Michael T
authors.initials: MT
authors.lastname: Rohmiller
authors.forename: Eric C
authors.initials: EC
authors.lastname: McCarty
authors.forename: Jake
authors.initials: J
authors.lastname: Block
mesh_terms: D000388:Air; D006801:Humans; D007270:Injections, Intra-Articular / Q000379:methods*; D007719:Knee Joint; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013016:Sound