Owning The Ankle Arthrocentesis

Author: Andrew Cunningham, MD (EM Resident Physician, PGY-1, NUEM) // Edited by: Victoria Weston, MD (EM Resident Physician, PGY-4, NUEM) // Expert Commentary: Christopher Hogrefe, MD

Citation: [Peer-Reviewed, Web Publication] Cunningham A, Weston V (2016, June 14). Owning The Ankle Arthrocentesis [NUEM Blog. Expert Commentary by Hogrefe C]. Retrieved from http://www.nuemblog.com/blog/ankle-arthrocentesis/

As ER doctors, we stick a lot of needles into a lot of different body parts. Sometimes into vessels, sometimes into the area around the spinal cord, and of course, sometimes into hot, swollen joints. The ankle is included in this, and I’m willing to bet that many of us have had a more-than-troublesome tap. To help you through your next angry ankle, here are a couple of pointers!

The Classic Method

Finding Your Spot

Palpate the anterior border of the medial malleolus and the tibialis anterior tendon. Your looking to enter in the space between these two structures [4].

Positioning is key. Have your patient lie supine, and plantar flex the ankle so the angle between the heel and the posterior leg is as close to 90 degrees as you can get it [4].

Aseptic Technique

  • There is no standard method for cleaning your target site. Most literature recommends applying several layers of iodine followed by alcohol, but some studies have suggested that this is roughly equivalent to using alcohol alone [4].
  • You don’t necessarily need to sterile gloves for this procedure, but remember, if you don’t use sterile gloves, you cannot re-palpate your target area after you have cleaned it [4]!


  • Use a 25 to 27 gauge needle to create a wheal of local anesthetic, and then keep injecting down to the area of the joint capsule. Alternately, instead of a wheal, feel free to use spray coolant as your first form of local anesthetic [1,4]. 
  • Patient relaxation is essential to making this procedure easy. If your patient is uncomfortable, muscles tighten, and your joint space becomes harder to enter. The synovial membrane and the periosteum have lots of nerve fibers, so make sure you have adequate local anesthetic before starting [1]. 


  • Introduce a 20 to 22 gauge needle into your previously located spot, keeping your needle perpendicular to the shaft of the patient’s tibia. If you hit bone, withdraw slightly and redirect at a different angle. Don’t get too nervous if you hit bone; this won’t damage the cartilage [1,4]!
  • When you’ve inserted your needle approximately ½ of an inch, begin aspirating. If you start to freely get fluid back into your syringe, you’re in the right spot!
  • If the fluid stops or starts to slow down, consider either slightly advancing, retracting, or rotating your needle [4].
  • If your syringe starts to fill up, and you need to get more fluid out, use a pair of hemostats to grasp the tip of your needle and change your syringe [7]. 


  • If your patient has already been diagnosed with gout, and you are injecting the ankle with steroids as opposed to only aspirating the ankle, tell the patient to avoid strenuous activity for the next 24 to 48 hours. In addition, remind them that they may experience worsening symptoms for the next 1-2 days due to a possible steroid flair, and to take NSAIDs to help with those symptoms. Finally, ensure they have close follow up. 

“Dry Taps”

  • If you think you truly are in the joint space, but you aren’t getting any fluid back, consider the “backflow technique”: inject a small amount of saline, and see if you are able to aspirate it back. If so, you are in the right place [4]. 

Using Ultrasound

Now that we’ve covered the tried and true basics, let’s discuss how to kick your tap up a notch with the ultrasound! Plainly speaking, the ultrasound offers many benefits over the standard approach: it makes it easier to located and avoid the tibialis anterior (TA) and extensor hallucis longus (EHL) tendons, easier to locate and avoid the dorsalis pedis artery, and increases the overall success rate of fluid aspiration as well as improves patient outcomes after injections [2,3].

Positioning the Transducer

Identify your anatomy before you start. First place the probe in an axial view to help locate the TA tendon, EHL tendon, anterior tibial artery, and deep fibular nerve [6].

To locate your joint space, place the center of the probe in between the TA tendon and EHL tendon, then rotate longitudinally with the probe marker facing the patient’s head. Placing the probe just lateral to the EHL will allow for better visualization of the joint space (just remember, this isn’t where you’re injecting, you’re inserting your needle medial to the TA tendon) [5,6].


If present, an effusion will look like a black triangle between the tibia and the talus [1]. Please note, there is no effusion in the picture below, but if there was, the space between the tibia and talus would appear more hypoechoic.


Needle Insertion

  • After finding the space with your ultrasound, insert your needle medially to the probe, being sure to avoid the tendons and other deep structures. Use a sharp angle to avoid scraping the talar dome. Although most described approaches use the longitudinal view, an axial view is acceptable if it helps the user successfully perform the tap under ultrasound [2,6].

Now, get out there and tap some ankles!

Expert Commentary

Dr. Cunningham,

Kudos on composing such an articulate, informative, and clinically useful article.  I might contend that you should try to avoid sticking needles directly into the spinal cord and focus on hanging out in the lumbar cistern/cerebrospinal fluid space.  Sarcasm aside, you have exquisitely detailed a phenomenal technique for accessing the ankle joint via an anteromedial approach.  I sincerely commend you on this work, however…

I respectfully disagree.

Well, I do not completely disagree.  As previously suggested, the anteromedial approach to accessing the ankle joint is quite appropriate.  In fact, it is the primary technique detailed in highly-regarded textbooks like Roberts and Hedges Clinical Procedures in Emergency Medicine.  But, you did not cite a plethora of studies noting the efficacy and/or superiority of this method compared to other potential techniques for performing an ankle arthrocentesis and/or injection.  This is actually rather astute of you because there is not exactly a veritable cornucopia of such data.  It would seem that the basis for many of the procedural preferences for this method is predicated on anatomy, which is a very valid consideration.

So if many (or perhaps most) textbooks highlight the anteromedial approach and there are anatomic considerations, why the civil and professional dissension on my part?  The first point to consider really involves managing this patient’s airway.  Yes, that is correct, I said managing this patient’s airway.  No, he/she did not suddenly develop fulminant sepsis secondary to septic arthritis, rapidly developing an acute airway issue.  There is no other medical mystery to solve here.  Hypothetically, consider for one moment how you might manage this individual’s airway.  You could perform a standard rapid sequence intubation, delayed sequence intubation, awake intubation, nasopharyngeal intubation, toss in an LMA, or perhaps even sound the alarm for a cricothyroidotomy.  Your airway of choice in this context hinges on any number of variables, but the fact of the matter is that sometimes not all of these options are viable.  There may be oral trauma or tongue swelling preventing intubation by traditional means.  The patient’s body habitus may provide other obstacles.  Time itself may force your hand.  The point is that having a Plan B with which you are comfortable is a strategy worth pursuing.

Image 1: Cellulitis of the anterior and medial ankle. (Image modified from: http://www.emstopics.com/LowerExtremity/LowerE1.jpg)

Reverting back to this patient’s ankle, it is entirely plausible that the medial ankle is suboptimal for the necessary procedure.  Consider the possibility that the patient has overlying cellulitis (such as in Image 1).  Carefully guiding your needle through this minefield should rarely, if ever, be entertained.  Or what if plain films of the ankle (which should be secured to evaluate for the possibility of gout/pseudogout, loose bodies, and the baseline bony alignment) reveal prominent medial ankle osteoarthritis?  How about the patient’s history of a previous traumatic deformity of the medial ankle?  Such situations would not invalidate Dr. Cunningham’s theoretical approach to accessing the ankle, but they would make his method suboptimal (at best) or borderline impossible (even with the use of ultrasound-guidance).

Enter the anterolateral approach to the ankle arthrocentesis.  Having trained in both techniques, I freely admit my bias toward this method.  In my hands, I find this approach more straightforward and, frankly, a bit easier to perform.  However, that assertion is anecdotal.  The question is whether or not there is data noting superiority of one technique, either in safety and/or efficacy.

Before we try to settle the debate regarding which method is superior, we should probably (briefly) describe the anterolateral approach.  This one might be easiest if you use yourself as a model.  If you palpate around the anterior, lateral ankle you should note a soft spot just anterior and slightly inferior to the lateral malleolus.  Note that you should be lateral to the extensor digitorum longus (EDL) tendon (Image 2) [8]. Adding some forced plantar flexion will assist in opening this space even further.  If you experience difficulty identifying the border of the EDL, performing resisted dorsiflexion of the ankle will aid in making the aforementioned landmarks even more prominent [9]. With the points of interest identified all of the standard preparatory actions detailed by Dr. Cunningham still apply.  At that juncture insert the needle at roughly 45°, moving posteriorly, slightly cephalad, and medially.  The synovial fluid should then come forth.

Image 2: Approaches to the ankle arthrocentesis. (Image modified from: http://img.medscape.com/pi/features/slideshow-slide/arthro-practice/fig9.jpg)

Now having considered the nuances of both techniques, it should be noted that the anteromedial approach as explained by Dr. Cunningham is often touted as being safer from an anatomic perspective.  As an aside, there is another anteromedial approach that could be attempted, as Image 2 suggests.  This method involves accessing the intra-articular space by navigating the area between the extensor hallucis longus (EHL) and tibialis anterior (TA) tendons.  Obviously, that can be tenuous territory.  Meanwhile, Dr. Cunningham’s technique appears a bit safer, primarily carrying the potential risk of injury to the greater saphenous nerve or the saphenous vein if one is too medial.  This danger is often asserted to be less than that associated with the anterolateral approach, which presents some peril to the dorsal intermediate cutaneous branch of the peroneal nerve.  This concern is justified, but with adequate forced plantar flexion the aforementioned cutaneous nerve is placed under tension.  One can then visualize the nerve readily under such conditions in order to avoid this would-be pitfall.

Anatomic manipulation aside, what does the literature say about one technique to an ankle arthrocentesis versus another?  An article from The Journal of Bone and Joint Surgery (British Volume) helps to shed light on the matter.  The authors took a couple of Orthopaedic Surgery residents, handed them 38 cadaver ankles along with a tub of methylene blue, and let them inject the ankles via both approaches.  Then, they verified the success (or perhaps failure) of the injections with arthrotomies.  And the results?  Well, it turns out that both methods are fairly accurate, with the anteromedial approach successful in 31 of 40 attempts (77.5%; 95% CI = 64.6% to 90.4%) and the anterolateral approach verified in 31 of 36 ankles (86.1%; CI = 74.8% to 97.4%).  The p value works out to 0.25 [10]. Thus, while there appears to be a trend toward the anterolateral method being more accurate, it does not quite meet statistical significance.  And to Dr. Cunningham, I offer a draw with regard to technical success of either technique.

After such a lengthy diatribe it may be the case that we are in the process of removing the need to nitpick between these methods.  As Emergency Medicine providers, we continue to enhance our proficiency in the use of ultrasonography, thereby further reducing the risk of these procedures.  It goes without saying that the visualization of the needle entering the ankle joint space is a remarkably powerful tool.  As we grow along with this technology we can better identify the nerves, tendons, and vasculature at play, avoiding them and the complications that can come with piercing them.  For the skeptics among us, some of the evolving research analyzing this topic supports the use of ultrasonography.  Reach, et al. report a 100% accuracy rate with ultrasound-guidance for intra-articular ankle injections [11]. Not only that, but other literature suggests that it actually requires less time to complete a successful ankle (and other small joint) arthrocentesis with ultrasound-guidance compared to a landmark-based approach [12]. It is fairly safe to assert that each of us should strive to add this tool to our armamentarium when attempting to aspirate or inject an ankle (any many other joints for that matter).

In conclusion, the conversation I initiated appears to have come full circle.  Two possible approaches, both of which seem relatively similar in terms of efficacy and safety, further enhanced with the use of ultrasound…How can you go wrong?  In the Emergency Department, I suppose that there is always a way that something could go wrong.  But I think that Dr. Cunningham has laid out a sound technique for performing an ankle arthrocentesis.  Hopefully, I have done the same.  Practice both methods, just as you will or have developed different skill sets for managing a patient’s airway.  If you do so, with the aforementioned information in tow, you should be confident the next time you have to tap that ankle.

Christopher Hogrefe, MD, FACEP

Assistant Professor; Department of Emergency Medicine; Department of Medicine - Sports Medicine; Department of Orthopaedic Surgery - Sports Medicine; Northwestern Medicine; Northwestern University Feinberg School of Medicine


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