Patient Education and Consent
Verbal consent is usually sufficient for joint aspiration (arthrocentesis). The patient should be informed of the risks of the procedure, which include the rare occurrence of bleeding into the joint, fainting, or infection. The risks of not performing arthrocentesis include failure to make the diagnosis and the consequent associated morbidity. Any allergy (eg, to preparation material used or latex gloves) must be investigated.
Equipment
Personal protective equipment includes the following:
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Gloves
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Face shield (optional)
Anesthesia equipment includes the following:
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1% lidocaine solution
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25- or 27-gauge needle
Sterilization materials include the following:
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Povidone-iodine solution or chlorhexidine
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Alcohol wipes
Aspiration materials include the following:
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1.5-in. (3.8-cm) 21- to 18-gauge needle for large joints (eg, knee, ankle or shoulder)
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1-in. (2.5-cm) 21-gauge needle for medium joints (eg, wrist)
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1-in. (2.5-cm) 25-gauge needle for small joints (eg, metacarpophalangeal [MCP] or metatarsophalangeal [MTP])
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Longer needles if needed for deep joints or very obese patients
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3-, 10-, or 20-mL syringe, as appropriate for the joint and the size of the effusion
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Adhesive bandage
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Sterile gauze
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Heparinized (green top) tubes and sterile culture bottles (optional)
Patient Preparation
Before the procedure is begun, the joint landmarks should be carefully palpated, and the needle insertion point should be marked with ink or indented into the skin with the tip of a retracted pen.
The area should be prepared with povidone-iodine solution and then allowed to dry. The iodine can then be wiped away from the needle insertion site with an alcohol pad to prevent irritation. In patients allergic to iodine, chlorhexidine is an acceptable alternative. Once the procedure is completed, excess iodine should be removed from the skin.
Anesthesia
If desired, 1% lidocaine without epinephrine can be instilled into the skin and subcutaneous tissue over the anticipated tract of the needle; 1 mL of lidocaine is usually sufficient. As skill improves, only ethyl chloride spray for anesthesia may be used in certain cases.
Positioning
The joint to be aspirated should be resting on a hospital bed, table, or other stable, immobile structure. The patient should always be lying or sitting down and should be at a comfortable height for the physician. For details on how to position the patient for specific joint aspirations, see Approaches to Specific Joints in the Technique section. These positions are designed so that the joint capsule bulges forward towards your needle.
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Medial approach to aspiration of ankle joint.
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Medial approach to aspiration of knee joint.
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Anterior approach to aspiration of glenohumoral joint. Point where coracoid can be palpated is marked with "C."
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Approach to aspiration of the wrist joint.
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Approach to aspiration of elbow joint, with landmarks labeled. LE = lateral epicondyle; R = radial head; O = olecranon.
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Medial approach to aspiration of metacarpophalangeal joint.
