Ankle arthrocentesis is an important skill to master as an Emergency Medicine physician as it allows you to perform both diagnostic tests and therapeutic interventions which can change the course of a patient’s disease process.
Indications for ankle arthrocentesis
Joint fluid analysis to evaluate for varying forms of arthritis, most pertinent in the ED being septic arthritis.
Evaluation of the joint for capsule violation after trauma
Drainage of fluid from capsule
Pain/symptom management for chronic conditions (steroid/hyaluronic acid injections)
Anterolateral approach: In this approach, the joint line is located in the space between the lateral edge of the extensor digitorum longus (EDL) and the medial edge of the lateral malleolus. See yellow arrow on Figure 1. The ankle is actively extended to widen the joint space, and the needle is inserted perpendicular to the tibial shaft about 3-4cm.  This is the preferred approach given a lower likelihood of hitting the dorsalis pedis (DP) artery and peroneal nerve. 
Anteromedial approach: In this approach, the joint line is located on the medial aspect of the ankle in one of two spaces :
The space between the extensor hallucis longus (EHL) and the lateral aspect of the tibialis anterior (TA). See the blue arrow on Figure 1. In this medial approach, use caution as the peroneal nerve and DP artery are just lateral and slightly inferior to the EHL. The needle should be directed at a 90 degree angle towards the Achilles tendon.
The space between the base of the medial malleolus and the medial aspect of the tibialis anterior. See the red arrow on Figure 1.
Position the patient so that the ankle is in plantar flexion either with the heel on the bed or with the plantar surface flat on the bed.
Identify landmarks as described above and mark site of entry
Clean site with chloraprep or iodine 
Using a 22 gauge needle, inject lidocaine with or without epinephrine into the skin, creating a wheel. Then advance the needle into the projected path and inject along the pathway.
Attach a 5-10 cc syringe to a 22 gauge needle and advance the needle into the joint space (about 3-4cm in a normal size person). While advancing, pull back on the plunger to create negative pressure in the syringe.
If you do not get fluid but believe you are in the space, inject a small amount of saline into the joint and withdraw. If you are able to get it back, you are most likely in the joint space.
While external landmarks can be easily identifiable, penetration of the joint space can be difficult without direct visualization. As an adjunct to landmarks, point of care ultrasound (POCUS) can be used to assist in ankle arthrocentesis. The ultrasound approach is as follows:
Place the foot in a dorsiflexed position with the ultrasound linear probe placed longitudinally with the indicator cephalad over the tibiotalar recess; probe position should be between the extensor hallucis longus and the lateral aspect of the tibialis anterior as described in anteromedial approach.
Fan the probe until you are able to obtain the view in Figure 2. The joint effusion is located between the tibia and the talus .
Insert needle on either side of the ultrasound probe with careful attention to the DP artery and peroneal nerve. (Figure 3).
Aspirate the effusion under direct visualization of your needle tip.
Ankle arthrocentesis is an important skill for emergency medicine physicians as it allows for rapid identification of septic arthritis and other ankle pathologies
Utilize landmarks (EDL, EHL, TA) to help guide your ankle arthrocentesis and prevent inadvertent damage to the dorsalis pedis artery or peroneal nerve
POCUS can be a helpful adjunct in identifying joint effusion as well as the dorsalis pedis artery and peroneal nerve during needle insertion
Involve orthopedic surgery early when concerned for possible septic arthritis to allow for definitive therapy with joint washout
AUTHOR: Payton Leech, MD
Dr. Leech is a PGY-2 in Emergency Medicine at the University of Cincinnati
POST AND PEER EDITING: Shan Modi, MD
Dr. Modi is a PGY-3 in Emergency Medicine at the University of Cincinnati
FACULTY EDITOR Edmond Hooker, MD, DrPH
Dr. Hooker is an Assistant Professor of Emergency Medicine at the University of Cincinnati and Faculty Editor of the ‘Minor Care Series’
Purcell D., Terry B.A., Sharp B.R. (2019) Joint Arthrocentesis. In: Purcell D., Chinai S., Allen B., Davenport M. (eds) Emergency Orthopedics Handbook. Springer, Cham
Akbarnia H, Zahn E. Knee Arthrocentesis. [Updated 2018 Dec 16]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470229/Making content easier to read in BookshelfClose
Shlamovitz, Gil Z. “Ankle Arthrocentesis Technique.” Medscape, 2019, emedicine.medscape.com/article/79956-technique.
Singh, Arun Pal. “Ankle Arthrocentesis or Ankle Joint Aspiration.” Bone and Spine, 6 Aug. 2018, boneandspine.com/ankle-arthrocentesis/.
Roberts, W Neal. “Joint Aspiration or Injection in Adults: Technique and Indications.” Edited by Daniel E Furst, UpToDate, 2017, www.uptodate.com/contents/joint-aspiration-or-injection-in-adults-technique-and-indications/abstract/8.
Valley V, Stahmer S. Targeted musculoarticular sonography in the detection of joint effusions. Academic Emergency Medicine. 2001 8(4): 361-367.