musculoskeletal and connective tissue disorders
How To Do Knee Arthrocentesis
Step by Step Description of Knee Arthrocentesis
Palpate the knee to identify the patella. If desired, mark the needle insertion site with a skin-marking pen or preferably an indentation (before cleansing the skin). Rest the knee on an underpad. Prepare the site and surrounding area with a skin-cleansing agent, such aschlorhexidineor povidone iodine, then use an alcohol wipe to remove the agent. Place a wheal of local anesthetic over the needle entry site using a 25-gauge needle. Then inject more anesthetic into the deeper tissues along the anticipated trajectory of the arthrocentesis needle, but do not enter the joint space. Aspirate the joint using an 18- or 20-gauge needle on a 20- to 60-mL syringe. If using a three-way stopcock, the stopcock is installed between the needle and the syringe. Enter the skin in a perpendicular fashion and direct the needle posteriorly behind the patella, toward the intercondylar notch. To avoid touching articular cartilage with the needle, try to maintain a horizontal needle trajectory; also, you may grasp the patella and gently pull it upward. Pull back on the plunger gently as the needle is advanced. Synovial fluid will enter the syringe when the capsule is entered. If the needle hits bone, retract almost to the skin surface and then redirect at a different angle. If aspiration is unsuccessful, you can try moving from a position of slight knee flexion to complete extension or try the procedure from the opposite side of the knee. Aspirate as much fluid as possible. Apply gentle pressure to the suprapatellar region to help drain extra fluid. In large effusions, a second syringe may be required. You may leave the needle in place by holding it securely with a hemostat or by using the three-way stopcock during syringe exchanges. If intra-articular medications (eg, anesthetic, corticosteroid) are to be given, hold the hub of the needle motionless (using a hemostat if available) while removing the synovial fluid-containing syringe and replace it with the medication-containing syringe. If the needle has remained in place in the joint space, there will be no resistance to medication injection. After injecting a corticosteroid, move the joint through full range of motion to distribute the medication throughout the joint. Transfer synovial fluid to tubes and other transport media for Synovial fluid examination . Inspect the fluid for blood and fat. After aspiration, remove the needle and cover the site with an adhesive bandage or sterile dressing. © Elsevier Inc. All Rights Reserved. This video is for personal informational use. Users are prohibited from copying, reproducing, licensing, subscribing, selling, leasing or distributing this video. 