Arthrocentesis & Injections: Ankle Dx

Last updated: October 15, 2014

Patient Position: The patient should lie supine (or be seated) on the examination table.

Limb Position: In a lying position, the patient’s foot should be positioned perpendicular to the floor and partially plantar flexed (75 degrees).

Bony Landmarks: Medially, palpate the tip of the medial malleolus; laterally, the tip of the lateral malleolus; and anteriorly, the extensor hallucis longus ten- don. Draw a line (visually) from medial to lateral malleoli. Ask the patient to dorsiflex the big toe and note where the extensor hallucis longus tendon rises to bisect this line (Figure 4). The injection site is medial to the tendon intersection.

Site/Angle of Entry: To inject the true ankle joint, use an anteromedial approach and place the needle at the injection site described above. Enter at a 90 degree angle (perpendicular to the floor) and direct the needle slightly laterally (toward the Achilles tendon). The needle should be advanced more than 3 cm into the joint space. The ankle may also be approached laterally (adjacent to the subtalar joint) using the same positioning, but entering just anterior to and beneath the lateral malleolus, with a slight inward angle. Aspirate before injecting.

Amount of Injection: Use 20 to 40 mg DepoMedrol (or equivalent), with or without 0.25 mL of 1% lidocaine, in a total volume of 0.5 to 3 mL.

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