Bedside Musculoskeletal Ultrasound - SD

Introduction

Hello, my name is Jason Matthew Fields.
I am the Director of Emergency Ultrasound Fellowship at
Thomas Jefferson University in Philadelphia, Pennsylvania.
This lecture is going to be on some of the clinical applications of bedside,
musculoskeletal ultrasound, including
fracture reduction, hematoma blocks,
and arthrocentesis.
While there are a lot of potential diagnosis you can make with musculoskeletal ultrasound,
this lecture is gonna be geared more towards practical applications for the bedside clinicians,
specifically the emergency medicine clinician.
And we're gonna look at diagnosis of fractures,
tendinopathies and joint effusions, diagnostically,
and then also use musculoskeletal ultrasound
to help us procedurally specifically with hematoma blocks,
fracture reductions and arthrocentesis.

Musculoskeletal Ultrasound Technique

When doing musculoskeletal ultrasound, you wanna
use your linear probe pretty much the vast majority
of the time with high frequency and a high resolution.
And you often may want to use a standoff pad
or a water bath to help you,
especially when you're looking for your very near field focus,
your technique.
You wanna hold a probe like a pencil, rest your
fourth and fifth digits on the patient so you kind
of know where you are and aren't sliding all over the place.
If you're scanning any type of area
of infection, cellulitis, you want to use
a probe cover or not to contaminate the probe
and scan systematically through your area
of interest into orthogonal planes.
And in this example, you might see something wrong
with the technique.
And what's wrong with this technique is that
the sonographer hasn't made himself comfortable.
He's kind of hunched over doing the scan, and
that's gonna be something that will end your career
as a sonographer early because you'll put your back out.
So, raise the patient's bed up
or seat yourself,
or make yourself comfortable.

Water Bath Technique

Talking about a water bath, it's a very nice way to
image the distal extremities.
The water provides a perfect acoustic interface.
Literally, all you have
to do in you're doing this is have the patient put their
hand in the water, and then you can put the probe in the
water, and the ultrasound beams are gonna travel
through the water to the area of interest.
You don't need
to contact the skin, you don't need gel.
And this is all especially great for looking
at injuries in kids because kids, if they have something
that's injured, don't want anybody to touch it or examine it,
but they don't mind putting it in a tub of water
or so it feels maybe a little bit therapeutic to 'em.

Sonoanatomy of Soft Tissue

Reviewing the sono anatomy of the soft tissue,
we start with the skin, which is kind of thin,
hyperechoic line in the normal patient.
Below that you'll see the subcutaneous tissue,
which is this hypoechoic region kind of filled
with reticular hyperechoic strands.
Below that you'll see the fascial planes,
which often you can see some veins, arteries,
potentially a nerve, and
other structures kind of running through there.
Vessels
and nerves tend to be kind of hypoechoic,
whereas nerves can sometimes kind of a honeycomb appearance, and they demonstrate anisotropy,
which we'll talk about later.
The muscle layer comes next.
It is hypoechoic and often speckled in the transverse plane.
And after that, we can see some bone,
which is hyperechoic with posterior shadowing.
The muscle often has a different appearance in longitudinal
where as opposed to transverse,
it'll appear a little bit more laminar feathery like, or we often say pennate in the long axis.
And here's an example
of a vessel in the long axis compared to the short.
And the short axis is a circle
and the long axis, it turns into a long rectangle.
And here's just side by side showing the
different appearances of the muscle
and short axis on the left
and long axis on the right.
Tendons tend to have a brush like pattern
to them as all the fibrils run next to each other.
So we can see here, they're usually
in typical locations where you would expect to find tendons,
connecting muscle to bone
or inserting on bone.
Here's an example of a knee,
quadriceps tendon.
Here's another example where you can see, again, the
brush pattern of a tendon.
Tendons have a feature known as anisotropy.
This is a very important feature of tendons and helps you actually diagnose pathology.
What this means is since tendons are very highly reflective,
just like a mirror, when you look at it straight on,
you get a very vivid reflection.
But when you're at an angle to it,
you don't get any,
you don't see yourself at all.
Likewise, in tendons, when you're 90 degrees
to the tendon, you get a very sharp reflection.
But when you're off angle,
it turns hypoechoic, you don't see anything at all.
So here's an example of that,
with the left image being at 90 degrees
and the right image being off angle.
Here we see a biceps tendon going
through the bicipital groove, and it's the sonographer
is rocking the probe back and forth.
We can see this tendon light up and turn dark,
and that's because the angle's changing from 90 degrees
to more or less than 90 degrees when it turns dark.
This is important
because if a portion of the tendon remains hypoechoic,
despite being at a 90 degree interface, that suggests
that there is tendon damage there.

Diagnosing Fractures

Talking about fractures,
people wonder why you use
ultrasound for fractures.
Some reasons are it's quick, it's at the bedside,
and you can place it over the tender area and have an immediate
correlation with clinical exam.
And I find this especially useful in cases where
I'm worried that there might be a radiologically occult fracture because my clinical suspicion is so high
and they have such a point tenderness,
I could take a look with an ultrasound
and rule in the fracture that way,
you can also get extra information as opposed to an x-ray,
which only looks at the bone.
Here, you can look at other causes for the pain, such
as a muscle tear or tendinopathy.
And it's especially useful in austere environments.
We have a global health fellowship
where we send our fellows to Sierra Leone
and at their regional medical center there, they
actually do not even have an x-ray machine.
It's such a poor country that they don't have these resources.
So in the clinic, the ultrasound machine that we have
is the one of the only diagnostic medical imaging that you can find.
So very useful for diagnosing, ruling in fractures.
When you compare ultrasound versus x-ray,
it turns out that ultrasound is actually better than x-ray
for diagnosing rib fractures.
It's very similar to x-ray for looking at long bones,
especially in the mid shaft region, nasal bones and sternum,
and it's inferior to x-ray when you get into complicated
bony areas such as metatarsals, metacarpals,
proximal femur and hip.
So you want to ultrasound the bone in the long
and short axis using a high frequency linear transducer,
look over the point of tenderness,
and also make sure that you do a contralateral examination
and compare findings.
And what you wanna look for is decortication.
This is an example of a patient who came in
with a clavicle injury.
And here we can see that the bone,
there's a decortication here in the
bone is a fracture.
Clavicle fractures have been studied,
and this is a pediatric study
and found to have very high sensitivity
and specificity in the 95
to 96% range when compared to x-ray.
So very easily this was done
by bedside sonographers, clinician sonographers, so easy
to do and a good test to rule in the diagnosis.
Here's a patient who fell on an outstretched hand and
has a deformity.
And here we can see a decortication here.
This is a left radius here looking there.
And we can see the decortication. This is a Colles fracture.
This was a 24-year-old male who was hit in the chest
with a baseball bat and has you can, when you do your exam, you feel
that there is a little bit
of a step off there in the sternum.
So you take a look at the ultrasound.
And one of the things
that's useful in musculoskeletal ultrasound is
applying a little bit of pressure.
You have to be careful when you're doing this in a
patient with a suspected fracture.
But what we see in this image here is the sternum.
There's a decortication in the sternum,
and it's a little bit posteriorly dislocated.
There is a little bit of periosteum intact here.
You can kind of see bridging
between the two fracture fragments.
This is a patient who fell on their side
and had a lot of rib pain.
Normal chest x-ray though.
So clinically suspected for a rib fracture.
Wanted to be able to make the diagnosis just
to tell the patient what to expect
and how long they would expect to have pain.
And using an incentive spirometer for.
So we took a look here.
This is the long axis view of the rib here,
and we can see decortication there and there.
So diagnostic of a rib fracture.
This was a case that I saw with my resident,
and the patient had clinically what appeared
to be a shoulder dislocation.
However, when you examined the patient,
it didn't seem quite right.
The patient, the resident, was eager to get this arm reduced
and setting up for the procedure when we decided to, let's
make sure that this is not a fracture.
And taking a look is very easy
to see the decortication and
rule in a humerus fracture.
When you look at it in transverse, you can see the drop off there between the two fracture fragments.

Ultrasound for Procedures

So I often like to think of ultrasound as like my own bedside fluoro.
It can be used for procedures, fracture reduction,
shoulder dislocations, and foreign body removal.
And the advantage is it's quicker, smaller, less bulky,
simple, you don't need an additional technician,
and there's no radiation.
So here's a case that I saw not too long ago in the ED, a patient who has a fall
and outstretched hand injury.
And when we did the ultrasound, we saw the could see the fracture dislocation there.
And so we had a couple issues we needed to deal with.
One is we need to control this patient's pain,
and two, we need to reduce the fracture.
And so my algorithm for this is
to an ultrasound-guided hematoma block, followed
by an ultrasound-guided fracture reduction.

Hematoma Blocks and Fracture Reduction

So the ultrasound-guided hematoma block is
very simple to do.
You basically identify the fracture site and aim the needle for that area.
You make sure you see if you aspirate any blood and then you infiltrate with
a local anesthetic.
A lot of different recipes for this,
but 15 mls of 1% lidocaine works just fine.
And basically what happens is,
as you inject into that fracture site, the broken ends
of the periosteum will absorb that lidocaine and
anesthetize the periosteum and surrounding tissue.
And so after doing this, we were able
to manipulate the patient.
One thing that's recently been reported is
you can also do a supracondylar radial nerve block for this kind of fracture reduction.
This was a case report, so something that's kind
of new, but it's also potentially useful.
So after we did our manipulation, we checked again
and you can save your initial image
and scroll and then save your reduction image
and flip back between the two to kind of see how you did
or even use a split screen.
But when we compared our before and our
after, we felt like we had pretty good reduction
of this distal Colles fracture.
And so then we splinted the patient
and sent for a repeat x-ray
and felt like it looked pretty
good and sent the patient home.
Here's another example of a patient
that had a comminuted fracture.
You can see the displaced
fracture fragments here on the left.
And over on the right, this was after reduction.
So this has been studied and
been fairly well validated and improves actually the reduction,
the need for repeat manipulation,
which is a very painful thing when you have
to send the patient to x-ray, then you find
that it's not a good reduction, bring 'em back,
re-anesthetize 'em and do another procedure again.
A study in pediatric population found
that ultrasound had a very good sensitivity
and specificity for diagnosis.
And success
of reduction using ultrasound guidance was high
as well 92%.

Tendinopathies

Moving on to tendinopathies,
we're gonna look at partial tears, complete tears,
and talk about tenosynovitis.
Again, here we see the brush pattern of the tendon in this example.
A tendon that I like
to look at in the emergency department is very easy,
readily available is the Achilles.
And here is a very normal looking Achilles tendon.
Starting superiorly.
We see the feathery like appearance
of the gastrocnemius muscle above that go back here.
Above that, we see the takeoff of the
Achilles tendon traveling and going in
and inserting on the calcaneus back here.
So the issue, the reason I like
to use this in the emergency department, is not really
to diagnose a complete Achilles rupture.
Those are actually very, usually very obvious clinically,
but actually to look more
to see if the patient has a partial Achilles rupture,
in which case splinting the patient might be useful
and expedited follow up with orthopedics.
So here's a case of a 35-year-old male
who stepped into a hole and hurt a pop,
and he was very tender over his Achilles.
He had a normal Thompson test.
In other words, whenever you squeezed on his gastrocnemius muscle,
he still had intact plantar flexion of his foot.
So it's not clinically a full rupture,
but high suspicion for a partial rupture.
So the first thing I would say is it's nice
to look at the normal unaffected side.
And here we see a nice brush pattern running through,
from the calcaneus there all the way up
to insert on the gastrocnemius.
I'm sorry, I apologize. The image is a little bit dark.
But on the affected side, we
see something different.
We see kind of a more heterogeneous picture
where the tendon is.
And this is due to there's some hyperechoic bleeding as well as swelling
of the tendon and some loss of anisotropy.
So this is suggestive of a partial tendon injury.
And I'm gonna show this in short axis.
It might actually be a little bit easier to see here.
We see in short axis that the normal side is a
the tendon is very tight bundle.
And over on the affected side, the tendon's swollen,
enlarged and has a lot of heterogeneous appearance to it
with some hyperechoic bleeding
and again, loss of anisotropy.
Here's another example of a tendon.
And as you scan down,
you can see down here there is a fairly smooth brush
pattern, but up here we have all these hypoechoic areas and loss of anisotropic suggestion of
a partial tendon injury.
This is a patient that had a hyperflexion
injury of his right knee.
And on the unaffected side on the left here, we see
that the patella here and the
patellar tendon is intact
with a smooth brush pattern.
But over here, we see the we don't see that smooth brush pattern,
and we see just kind of a lump mass here at the base of patella.
So what we have here is a complete patellar
ligament disruption.
So another thing I like to use this for is a bedside
tendon exploration.
So here is a patient that had a fracture but also had a laceration over the fracture.
So the question is was the overlying tendon
of the bone there also injured?
So oftentimes, traditionally we would anesthetize this
and explore this at the bedside which was done in this case.
But we also took a look sonographically
because no matter how much you explore,
it's very difficult to visualize the full tendon.
So whenever we took a look sonographically of this patient, we felt like the tendon looked well intact.
So here we see the laceration here, we see the fracture,
and in between we can see it looks like a nice healthy tendon there.
And in this case, what we actually believed happened was this was blunt trauma.
So this was more of a break in the skin from blunt trauma.
And the pressure had probably caused this fracture,
but there wasn't actually a true laceration from the laceration to the fracture.
And I think that's well demonstrated
here by this ultrasound.
This is the same image just having the patient clinch his fist to recreate the position that the fist was in when the injury occurred.
This gives us causes the laceration to be much more overlying the fracture, kind
of recreating the position of injury.
This is a patient with intense pain, flexion posture,
swelling and percussion tenderness.
So clinically worrisome for a tenosynovitis.
And you can see that on ultrasound.
This is using the water bath.
You can see the tendon running through there,
that nice brush pattern, and you can see fluid around it.
That's another example of tendons
with fluid surrounding them in a flexor tenosynovitis case.
And sometimes you can just make other alternate
diagnoses in patients.
So here's somebody who had blunt trauma
to the right arm had a lot of pain, a lot
of focal tenderness there and swelling and a negative x-ray.
And when you look with ultrasound, you can kind
of see the muscle tissue over here.
And in the middle you can kind of see this fluid collection is a biceps intramuscular hematoma.
Here was another patient that I saw with one
of my residents who was worried this guy had been trying
to step up on a ladder, hurt a pop in his pain and had gotten pain and swelling in his calf,
but she was concerned that could it be an Achilles injury.
And clinically when you look at this,
you're not too suspicious of a, at least a complete tear
'cause his Achilles tendon is look intact.
But there is some calf swelling
that's appreciable.
So when we ultrasounded his Achilles,
they look completely normal.
But when you looked up in that calf region, you could see a intramuscular hematoma tracking in
between the gastrocnemius and soleus muscle.
And so that was the diagnosis there.

Joint Effusions and Arthrocentesis

So effusions, common
emergency department complaint is a hot swollen joint.
Here we have a 67-year-old male with an atraumatic,
right ankle pain, erythema swelling.
And while in my practice do a lot of knee arthrocentesis, ankles,
wrists, shoulders, hips, those are joints that I
don't tap on a day-to-day basis.
And so they can be very difficult and challenging.
So we often struggle with the question is whether we should even tap
or not, are we gonna get fluid out?
And where should we go with the needle to make to be the most high yield spot?
So ultrasound can help with both of these.
You can really identify whether a tapable effusion even
exists and it can help you guide the procedure.
So like other fluid collections,
joint effusions appear hypoechoic
or dark, this is a knee
and they're easily identifiable.
So here is an ankle effusion.
We're looking here at the tibiotalar junction
on the left.
And that's a normal one
where we don't see any fluid collection.
On the right, we can see an ankle effusion easily tapable.
This was an example of a wrist.
Clinically this was very difficult
to determine whether there was a fluid collection,
but sonographically we can see it very well.
It's not very large,
but potentially able to drain some fluid from it.
And here's an example of a hip, which is very,
very difficult to determine if there's an effusion there.
But here we can see it sonographically.
This was an MTP joint effusion.
And so
whenever we do arthrocentesis, I like
to say that there are three steps.
The first step is identify the effusion.
The second is to take measurements,
and the third is to choose either a
guided or landmark method.
So first we have identified the effusion.
Here we see the femoral head, femoral neck,
and we see a hypoechoic effusion anterior to that.
So then we wanna take measurements
and we can measure the size of the effusion,
but more importantly, we also wanna measure the distance to the effusion.
So you can see in that right side image,
that's the distance from the skin to the effusion.
And this was important in this case
because it made us realize
that this effusion was over four centimeters deep.
So requiring even a longer needle to reach it.
And then you want to use either the landmark technique or you can do an ultrasound guided technique.
The landmark technique is to make pin markings where you saw the effusion,
and then go back to your traditional tools
and method to actually do the arthrocentesis.
I like to advocate this method
because it's simpler for people.
Holding the ultrasound probe
and trying to watch the needle on ultrasound guidance can require a lot of dexterity
and often people might lose the needle tip.
So at least doing it this way, you're cognizant of
how deep your needle's going.
And you can always mid-procedure,
if this technique isn't working very well
and you think your needle may have gone in the wrong place,
you can always leave the needle in
and pick up the ultrasound probe with a sterile cover
and put it back adjacent to the needle to see
where your needle tip is and how close to the effusion it is.
You can also do the ultrasound guided technique.
Here's an example where we can see the joint
and see the needle tip coming into
that effusion and where it's draining.
So here's a study done
to look at patients with joint pain,
swelling, and erythema, and
where there might be concern for an effusion.
And they asked the treating physician what the likelihood
of an effusion prior to ultrasound was,
and they performed the ultrasound
and of 54 patients in which aspiration was initially
planned, aspiration was initially planned in 39 cases
prior to ultrasound, and only 20 cases
after, so showing that a lot of times you can
might think there's an
a joint effusion when actually a
tapable effusion doesn't exist.
So this really cuts down on the amount
of unnecessary procedures we're doing time spent
and potential complications.
This was a study looking at bedside sonography
to identify hip effusions in pediatric patients.
Here's a picture showing the femoral head,
the anterior surface, the femoral head,
and the posterior surface of the iliopsoas muscle.
And that's where the effusion will develop.
In between those two, they found that this
had pretty decent sensitivity, but much higher specificity.
So a nice rule in test that can be done easy
by the bedside clinicians.

Pearls and Pitfalls

Pearls and pitfalls of musculoskeletal ultrasound.
You wanna make sure you communicate with the patient,
find the most tender region, always do a contralateral exam
to look at a normal versus abnormal,
although you have to be, keep in mind
that there's always the possibility
that the patient might have bilateral pathology.
Not too common in the emergency department, but
can happen pitfalls are trying
to look at fractures in difficult places like the wrist
and the hip might lead you to have a false negative,
failure to create a 90 degree angle of insonation
with the tendon making you think
that there is tear when one actually doesn't exist.
And failure to fully evaluate a joint space.
So
whenever you, especially when you're looking
for an effusion, you may miss it if sometimes the effusion is hiding up more
posteriorly than where you were looking.
And inappropriate gain settings are often an issue
with musculoskeletal ultrasound,
making you miss a fluid collection if the gain's too high,
or not visualize a fully intact tendon if the gain was too low.
And that concludes this lecture on
musculoskeletal ultrasound.