My Ultrasonic Hearing Beats Your X-Ray Vision

The official title for this is “Case Report of a Radiologically Occult Avulsion Fracture of the Fifth Metatarsal Diagnosed Using Bedside Ultrasound,” but that’s no fun and I think I just nodded-off while typing it.

The first vital piece of information for this story is that my girlfriend’s dog loves sticks. Here he is with one, certainly not running around like a crazy-person.

Gratuitous dog photo

I lied about it being vital info, but that gave me an excuse to post this picture.

One evening I was walking out of her house carrying a box and didn’t see that he had left one on the front steps, as he is wont to do from time to time. Unable to see in front of me, I stepped down with my right foot directly onto the stick. Lightening-quick reflexes weren’t enough to reverse my momentum and my full body-weight traveled downward onto my supinated and plantar-flexed foot, accompanied by the stereotypical CRACK of a badly rolled ankle. I was on solid ground (and still upright!) before I even knew what happened, but my foot wasn’t working quite right. I could bear mild weight but it certainly wasn’t comfortable. I managed to hobble to my car and make it home, deciding to evaluate the ankle the next morning in the hope that it would miraculously heal overnight.

Upon waking I could still bear mild weight, but the pain was significant and my foot exceptionally tender at the base of the fifth metatarsal. Realizing that I failed the Ottowa Ankle Rules, I figured I should head on over to the walk-in for evaluation by a real medical provider. Over there they shot some X-Rays, which were read as normal by the radiologist. Take a look if you don’t believe me.

Dorsal-Plantar View

Lateral View

Oblique View

The PA informed be that I had probably sprained my ankle, but if I wasn’t better in a couple of weeks I might have something more going on and may end up needing something like an MRI. He didn’t realize he was playing right into my plan…

Some folks reading this will know that a plantar-flexion/inversion injury is the classic mechanism for an avulsion fracture of the styloid at the base of the fifth metatarsal, also known as a pseudo-Jones or dancer’s fracture. Feeling pretty confident this had happened to me and having the day off, I stopped by my emergency department on the way home and stole-away with the ultrasound machine for a bit.

Using the linear array probe, I positioned myself as follows (those with an aversion to feet should note that I staged this photo a few days later at the end of a 12-hour shift, so you’re welcome). It’s a bit hard to see, but there’s a pretty significant amount of swelling that outlines where the probe should go; that’s always helpful. As expected, what we’re looking at is the base of the 5th metatarsal with the probe marker pointing proximal.

And here’s what I saw…

Right 5th metatarsal, avulsion fracture of the styloid.

Base of the right 5th metatarsal, avulsion fracture of the tuberosity.

These clips show a clear avulsion fracture of the 5th metatarsal styloid, visible as a discontinuity in what should be the otherwise smooth cortex of the bone. I apologize that the last two clips are backwards; I didn’t realize the screen automatically flipped when I switched from the “musculoskeletal” to “superficial” setting to play around with the image.

Just to be sure, I also shot some views of my uninjured left foot as well.

Base of the left 5th metatarsal, no fracture visible

Base of the left 5th metatarsal, no fracture visible

In case the anatomy was in doubt, these comparison shots of my healthy left foot show an intact cortex with no weird discontinuities.

How cool is that?? I’ll tell you that it’s pretty cool, but the big question is whether knowing there is actually a fracture present changes management. Some might argue that a patient in my position would be going home with supportive treatment and possibly even a diagnosis of occult fracture without the ultrasound confirmation. With good return and follow-up instructions and a bit of rest he or she would universally end up doing well from this very common and typically minor injury, so why waste time in a busy department doing this yourself?

While I can’t disagree with most of those points, I still think it’s worth the two minutes it takes to make this diagnosis with ultrasound. First, you can confidently tell the patient that they have a fracture, which reduces the chances of them forming a bad opinion of you when a repeat X-ray (or, God-forbid, more advanced imaging) confirms the diagnosis that was initially occult.

Second, patients will invariably be more cautious in how they handle a foot that’s broken as opposed to one that’s “just sprained.” I actually had a football game (not the American kind) planned for the night following my injury, and I can guarantee I would have been out there trying to play if I didn’t know I had a fracture. Understanding there was a legitimate fracture resulted in me taking something like 6-8 weeks off running until I was finally pain-free, though I continued to work in an emergency department spending 8 hours on my feet at a time so that wasn’t helping too much. Maybe the injury would not have taken any longer to heal had I tried to push through the pain and continued running on that foot, but I have a hunch that taking it easy for a bit was a good thing, especially since it gave me pain for far longer than the 4 weeks I was initially expecting.

Finally, I’m not exaggerating when I say it takes two minutes to do this exam. You ask the patient to point to where their foot hurts and stick the probe there. I’ve had absolutely no formal ultrasound training and had never even performed a musculoskeletal exam before the trying this on myself and still had no trouble finding and seeing the fracture. There’s a few pitfalls to keep in mind and you need to know your anatomy to do a fracture exam, but it’s still stupidly easy.

 

I’ve gone on too long already in this post, but Part II will feature a discussion of the anatomy involved in a pseudo-Jones fracture, while part III will feature a collection of clips taken at various points in the healing process for the curious. Please let me know if you have any questions or comments below or on the Ultrasound+ community page.

4 thoughts on “My Ultrasonic Hearing Beats Your X-Ray Vision

  1. GREAT post with an important message. I love your graphics – that totally illustrate your point without need to have prior knowledge of ultrasound. I agree – knowing that there was a definite fracture WAS important in determining optimal management in this case, as it may be with many others. Thanks for presenting.

  2. Dean Smith says:

    Interesting story, and something I’ve been thinking about for a while. I only occasionally ultrasound for fractures (ribs, sternum, as an adjunct to fracture reduction, or just curiosity while waiting for x-rays). What I’m wondering, is could U/S be used to rule out a fracture in low probability injuries. I’m thinking of something like a U/S modified Ottawa ankle rule…. OK, you can weight bear, but there is tenderness ( your Gestalt tells you this is a sprain, but OAR says to x-ray). Instead of x-ray, ultrasound first, and if clearly negative, call it a sprain and a day. The converse of course would be true, finding something suspicious for a fracture would prompt for x-ray. By way of a somewhat related anecdote, last night a woman presented with a painful somewhat swollen ankle. The swelling obscured a definite deformity, and she had diabetic neuropathy, so she had only minimal and poorly localized pain. She had been walking on it the past two days. I happened to be a walking by triage so took a quick look with U/S. Bimalleolar fracture with significant displacement! Not that this changed her ultimate management, but it bumped up her triage score, got her seen and reduced immediately instead of waiting 3-4 hours in fast track for a “sprained ankle”.
    Thoughts?

    • Vince D says:

      Thanks! A short time prior to posting I read this small study looking at just the kind of scenario you’re talking about (http://www.ncbi.nlm.nih.gov/pubmed/20943841). I’m not nearly good enough at this stuff and I don’t think the numbers are there to use it as a rule-out (yet), but I have a hunch this will be getting more talk in a few years.

      The big hurdle for gaining acceptance probably won’t be any flaws in the sensitivity of ultrasound but rather overcoming the ease with which X-rays can be obtained in most shops. With a click of the mouse most folks can get an XR shot and read by a radiologist, all while the emergency provider is getting other work done. That’s tough to beat, especially when most places aren’t set up to tie bedside ultrasound into the PACS system or billing. In a rural setting though, I know Casey Parker of broomedocs.com and his rural brethren do a lot of MSK ultrasound since getting films done can be a hassle.

      For now I’m loving the idea of using U/S to pick up occult fractures. It gives you a chance to show off the promise and superior sensitivity of the modality to folks in the department while also cinching diagnoses that would have been left grey in the past. I can guarantee that folks with occult rib Fx’s like to know that they’re not crazy or wimps for having so much pain.

      edit: I meant to add, thanks for reading and commenting! And nice pickup on that displaced bimalleolar fracture! I’ve worked enough Monday nights at the triage desk to know how much of a difference it can make to both the patient and provider to know that she hadn’t been sitting around for several hours before someone figured out her ankle needed mending.

Leave a Reply