A Simple, Accurate Method to Confirm Placement of Intra-articular Knee Injection
Glattes RC, Spindler KP, Blanchard GM, Rohmiller MT, McCarty EC, Block J.
Department of Orthopaedics and Rehabilitation and the Department of Radiology, Vanderbilt Sports Medicine Center, Nashville, Tennessee.
BACKGROUND: Intra-articular knee injections are routinely performed in clinical practice without documenting intra-articular placement. HYPOTHESIS: A small amount of air to an intra-articular knee injection produces an audible "squishing" sound with range of motion. STUDY DESIGN: 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. RESULT: 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%). CONCLUSION: Adding 1 to 2 cc of air to knee injections provides a no-cost, reliable, sensitive, and specific method of confirming accurate placement. Clinical Relevance: This simple method is easily reproduced, can confirm accurate placement, and can eliminate extra-articular injection as the reason for clinical response failure.
PMID: 15150053 [PubMed – in process]