Well,
today, in addition to going through all of
the information in this article, I'm just gonna
spend some time pimping you with questions that
came straight straight from this journal. I I
just need more people to ask me questions
that are just whatever pops into their head.
That's just the best. It's okay.
It's a safe environment. It's just you and
me. That's that's it. It's just you and
I having a conversation. I'm just gonna pimp
you on some questions. You know, if you
do terribly, we'll edit it on the back
end. It's not like I'm gonna put the
blooper reel in the front of this episode.
I'm very confident that my medical students got
to you with money, and I respect the
fact that now they're gonna have me pimped
on a national podcast. That's great. That's great.
Here we go.
Hey, everyone, and welcome back to another episode
of Amplify. I'm one of your hosts, Sam
Ashu. Before we dive into today's episode, I
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let's jump into today's episode.
Ladies and gentlemen, welcome back to another episode
of Emplify. I am one of your hosts,
Sam Michoud. And on the other side of
the microphone
Back at it again, doctor t r Eckler.
Could not be more excited to talk about
some knees. That's right. Today, we are talking
about the March 2025 emergency medicine practice issue
titled emergency department management of knee pain and
authored by three emergency physicians, one of whom
is also a professor of sports medicine. So
we've got doctor
Gingard, doctor Kiel, and doctor Riveros, and my
apologies to all three of them if I
butchered your names. I do that very commonly.
But they wrote,
once again, a wonderful volume on all things
knee pain,
which I thought was pretty timely. Honestly, I've
had knee pain recently. Had to go visit
the orthopedist myself. Suffered a little Tae Kwon
Do injury and was worried I might actually
have a meniscal tear because the pain wasn't
going away.
And
much like was listed in this article,
there are a bunch of physical exam tests
that can be performed
in order to try and determine
where the pain is,
and there are some specialty tests. And I
went through, I think, most of these with
the PA who saw me and did an
outstanding job, I might say. So this was
very timely and hit close to home. Thankfully,
I did not have a meniscal tear, and
things are on the mend, but we'll talk
more about that in a few minutes.
TR, you ever had knee pain? Ever seen
anybody with knee pain? I I have a
long interesting history of injuries, but I've never
actually done anything to either of my knees.
I think my my sister tore her ACL
when we were in high school, And I
just remember that process for her and just
the challenges of like the surgery and the
rehab and everything. And it was probably one
of the first points that I kind of
thought of like the value of a career
in medicine, because I saw how, you know,
that you had a chance to put people
back together. And I got to see the
inside of that process.
It was it was it was a cool
thing, and she's still really athletic and more
athletic than me. And I I respect the
fact that those surgeons managed to, you know,
make sure that she could still beat me
at most things. Fair enough.
Alright. So we're gonna start with the introduction.
Which of the following is the most common
etiology
of atraumatic
knee pain? So the most common. We've got
gout,
we've got osteoarthritis,
we've got septic arthritis,
and we've got meniscal tears.
I think it's osteoarthritis.
Osteoarthritis.
Yes, sir. T r for the win on
question number one. The major etiologies for atraumatic
knee pain are the ones I just mentioned,
but the most common is osteoarthritis.
No surprise there. The, article authors mentioned there
was six point six million knee injuries in
The United States over a ten year period
from '99 to 02/2008, which doesn't surprise me
at all, honestly,
with our extreme sports and our athleticism
and our ice storms down here in Florida
causing a bunch of people to slip. Knee
injuries seem very common. Credible amount of people
that got hurt in that snowstorm.
But, I can't help, but highlighting the fact
that,
you know, the osteoarthritis
while bad is on the rise,
particularly linked with like the bimodal distribution where
you have your extreme athletes, but also the
rising obesity in America. Like that's really driving
a lot of this. And then I, I
really was blown away by the fact that
31
of orthopedic practices
don't take Medicaid patients.
And that really, that really rang true for
the challenge of dealing with some of these
is that some of these people don't have
a follow-up option with orthopedics.
So trying to find any other way you
can to get them more answers or more
treatment, I think is pretty important to not
just assume that orthopedics is gonna be the
answer for these people.
Yes. Yes. And kudos to the authors for
putting that information in there to try and
drive home the relevance for knowing this information.
If your practice consists of, I'm gonna get
an X-ray, and I'm gonna send them to
follow-up with ortho and I don't care about
anything else, then a significant
portion of your patients, are not able to
get that orthopedic follow-up, and it makes a
difference whether or not you can give them
a definitive diagnosis
and a treatment plan. That's really the most
important is how are you gonna get rid
of this knee pain so you can get
back to work or back to your activity.
Interestingly, you mentioned already risk factors for developing
knee osteoarthritis.
Obesity is on the rise as well as
age and participation in sports and occupations. So
you can't forget to ask about what it
is that they do and whether or not
they're on their knees all day. That's a
very important differentiator.
When it comes to
osteoarthritis,
which of the following is a common risk
factor for developing osteoarthritis of the knee? Alright.
Ready? Here we go. ACL tear. This is
history, mind you. ACL tear, IV drug use,
high dose steroid use,
recent knee surgery, or rheumatoid arthritis?
So I would tell you, I would think
both recent knee surgery and
use of corticosteroids
would both increase your risk of osteoarthritis.
You're at fifty percent, sir. That's one correct
and one wrong.
Okay. Well, if I had to guess but
if I had to guess between the two
of them, I would say it's recent knee
surgery gives you No. Actually, you're you're
on the right track. You're definitely on the
right track. A history of prior injury or
prior surgery
is definitely a risk factor for developing knee
osteoarthritis.
The pitfall in this question is the recent
knee surgery because it just hasn't been long
enough yet to cause osteoarthritis.
The ACL tear, the history of a prior
ACL tear is the risk factor there, but
you're absolutely right. Injury That's because then they
had they usually they had surgery because their
ACL tear. Yeah. Okay. Yeah. Or they had
your previous trauma, and now it's healed. There's
been some time to get the osteoarthritis.
Here's a great step one question. That was
just there were so many layers of traps
in that question. I love Yes.
Indeed. Traps indeed. IV drug use is a
risk factor for septic arthritis. High dose corticosteroids
gives you a vascular necrosis over time, especially
with prolonged use. Recent knee surgery, again, if
if you wait long enough and it's healed,
then, yes, you get the osteoarthritis.
And then rheumatoid arthritis causes inflammatory, not degenerative
osteoarthritis.
So it's a trap question, but I had
to use it. I'm sorry. You just And
we see so many of the the knee
replacements to get done for osteoarthritis
because people just have that chronic pain that's
terrible, and then they end up getting a
replacement and they do well. And now, you
know, the orthopedic surgeons have invested in all
this pickleball courts just to make sure the
business keeps going, and I respect that. Yeah.
I mean, pickleball is a great sport. I
will say I have played it myself. I
love pickleball. Not not not usually. I don't
fit into that category of your typical pickleball
player, but we have a new pickleball court
here in town. And you'd be surprised how
many college students are out there playing it.
It's a great it's a fun sport. Alright.
Let's talk about infectious causes. So of all
of the different bacteria out there, this is
gonna be a little soft ball question for
you. What do you think is the most
common organism to cause septic arthritis for for
knees? Staph aureus. Yeah. All day, every day,
baby. Exactly. There was a study, a hundred
and five patients identified a causative agent in
eighty one of them, and it was all
staph. That's definitely the most common.
When it comes to the differential diagnosis for
atraumatic
knee pain, there is a giant table on
page five of the differential diagnosis that breaks
it down very nicely based on the location
of the symptoms. So the the number one
question to ask them is where is your
pain? And then you can go straight to
this table and go, oh, your pain is
anterior. Here's one, two, three, four different conditions
that can cause anterior knee pain, or your
pain is posterior or inferior. So an outstanding
table not only tells you the differential based
on location, but also a few extra notes
like septic knee and
dislocation
should be worrisome findings for somebody with this
kind of pain. And there is even a
little pediatric specific section of that table. So
something to keep in mind. I'm not gonna
read it to you, but if you have
access to the article, it's on page five,
an excellent differential diagnosis.
When it comes to prehospital care, I thought
the authors did a pretty good job just
driving home the fact that
most of these patients do not need to
go to the emergency department to begin with.
And if you're an EMS provider and you're
being called emergently for someone with knee pain,
then you've got some basic assessments to do.
Was there trauma? Is the knee obviously deformed?
And then it can be a little difficult,
but rarely knee dislocations can occur
from atraumatic mechanisms, especially in the morbidly obese
patient. And it can go unrecognized, completely unrecognized
because of the size of that patient and
because
small deformities in the knee joint may go
unrecognized.
And if you're the EMS provider,
sure you're gonna splint, you're gonna provide some
pain control, and you're gonna bring them. Some
things to note would be, do they have
a fever? Are they attack a cardiac? Are
they obviously septic and hypotensive? That's important information
to know when you pass them off to
the emergency department because it can alert us
early that there's some kind of sepsis going
on and that we need to address that
quickly.
Interestingly, and this is all the part this
is the part I always love reading. There
was a retrospective study, two hundred and seventy
seven patients that demonstrated that prehospital suspicion for
sepsis decreased
time to treatment
in the ED,
but no clinical outcome benefit was studied. So,
you know, we're very focused on time to
antibiotic because those are always the joint commission
metrics that we're looking at, but we're yet
to find any strong patient data in this
specific realm for septic knees, for example, that
tells us that the sooner, you know, whether
it's six hours versus two hours that you
get the antibiotic on board, are you really
affecting any clinical outcomes? So more data needed
when it comes to that.
Well, and also to your point, like, we
have such a pressure to give antibiotics now,
but in this case, if you really think
it's septic arthritis,
your clinical
diagnostic,
you know, specificity, sensitivity, if you if you
do the arthrocentesis and you get a good
sample before you give antibiotics,
you get like, I think a positive culture,
seventy eight percent of the time versus twenty
five percent of the time, if you do
it after broad spectrum antibiotics. So there really
is a value here, not to say, wait,
you know,
many hours or days, but, like, if you
can get that arthrocentesis
done, the value you provide for the patient
and getting them a specific answer and the
right treatment is there. So I think to
your point, you know, the the the value
is in establishing the diagnosis here and getting
the sample as opposed to,
you know, just throwing broad spectrum antibiotics at
it because.
Yes. Yeah. Absolutely. Completely agree. Although we give
antibiotics early in all forms of sepsis, if
there is a septic joint you're entertaining in
the differential, you gotta get a sample first
because it definitely affects your culture.
In the in the case for for EMS,
I had a case the other day where
they called me and they were like, this
patient's in severe knee pain. We can't tell
if it's dislocated or if it's patella. And
I kind of tried to talk them through
it and the field and they couldn't, they
couldn't quite kinda, you know, they couldn't send
me a video. Their, their connection wasn't that
good because I was trying to just get
a look at the knee to kind of
see what it was. And I kinda suspected
that it was, it was a young kid.
I kinda thought it might just be a
patella dislocation.
And, I was really just waiting for him
to get there because I was hoping I
could just pop it back in quick and
it was going to be the perfect end
of my shift. And one of our partners
just walked by as I was coming back
from the trauma bay and saw this patient
come in, recognized it as a patellar dislocation
and just popped it in and walked away.
And it just felt like just the cheapest
robbery at the end of my shift. And
I thought it was such a great move
by them because it was great for the
patient. But I just wanted to like that
moment of being the doctor that like, oh,
you just pop this in and it's no
big deal. And he he stole it, and
I just I appreciated the the the thievery
in that that case. I just thought it
was it was great great care by your
partners. It's also just a good cheap shot
at you. It is. It is it is
a satisfying maneuver to put that patella back
in. I mean, there is, I I think,
very few things that satisfy me when it
comes to orthopedic reductions, and the patella is
definitely one of them. I think it's number
two after, like, a nursemaid's elbow because it's
one of those things where if you can
really look him in the face and be
like, I know what I'm doing. You just
gotta count to two, and this thing is
done. And, like, we don't need sedation with
anything else because it's killing you right now,
and it's gonna be good in three seconds.
And just It is. It is one of
those count to three we're going on two
scenarios.
Exactly. Not gonna tell you.
Okay. So when it comes to history, we're
going to ask some key things. And, again,
an outstanding table, table two on page six
is all about questions you need to ask
for the physical exam. So if someone tells
you that they had sudden onset of pain,
you're going to be thinking about all of
those traumatic injuries. And then your follow-up questions
will be, did you hear a pop? Is
there some kind of knee instability? Are you
able to walk or weight bear?
Were you planting your foot and twisting?
Was there some kind of trauma involved? But
the sudden onset puts you in that mechanical
something has happened to your knee category, thinking
about things like ACL tears, meniscal tears,
quadricep tendon, patella fracture, patella ligament injuries. That's
all of your cues that this is going
to be an acute injury.
If they say it was gradual in onset,
then you've got a whole bunch of other
questions you need to follow-up with, like what
kind of activity makes it worse? Does going
up or downstairs make it worse? Does weight
bearing make it worse? Is it worse when
you first get up in the morning, or
does it get better throughout the day? Is
there something that you're taking that's alleviating the
pain? How long has it been going on,
etcetera? And then there's always
the important septic joint questions. Is there fever?
Is there warmth around your knee? Do you
have a history of IV drug abuse? Are
you immunocompromised
for any reason? And have you had a
recent knee
surgery, like, an a recent knee replacement so
that the presence of a recent knee prosthesis
is a risk factor for septic joint as
well. And that's an indication to get your
orthopedic colleagues involved very quickly. So Mhmm. Those
are all key historical clues that you need
to ask when it comes to your exam.
I found this mnemonic pretty helpful. Had you
ever heard about this IP PASS before or
IP PASS? It's a a mnemonic that stands
for
inspection,
palpation,
passive range of motion, active range of motion,
strength, and then special tests. So that's IPPASS
or IP dash PSS,
I IPPAS.
It's a, a mnemonic that's meant to guide
you through all of the physical exam findings
and tests that you need to perform in
order to try and figure out what exactly
is going on with their knee.
And speaking of giant tables,
table three in this article is on pages
seven and eight. It's the first two page
table I've seen.
It's it's exhaustive. And, honestly, I I wanna
say thanks to the authors for going through
the trouble of doing this because I think
trying to describe this in any kind of
textual paragraph format would have just been way,
way too long. It's a a list of
all of the specialized
knee tests that you can perform,
the description of how to perform the test,
and then the notes regarding
how you can make the exam more sensitive
and some of the things to keep in
mind. And it's all broken down by the
type of injury that can cause that test
to be positive. So everything from the ballotment
test to the LACMA test to the anterior
and posterior drawer tests, valgus and varus stress
tests, You've got all of the tests named
for people,
McMurray, Apley, Thessaly.
And you've got some iliotibial tests like the
noble and Ober test, the hop test for
stress fracture. There are lots of these specialized
tests, and honestly, I can't say that I
have done
many of these. Some of them are pretty
common, I think, but there are some of
these when I'm seeing someone in triage who
still has their pants on, I can't even
get a look at their skin, and there's
not a whole lot of space. I can
definitely see that these would be helpful, but
definitely would require a a stretcher for the
correct positioning in order to perform.
And I would tell you that I think
the this is a great article to basically
make you an expert in the care of
knee injuries. But I thought one of my
biggest takeaways was
the value they saw in bringing physical therapy
to the emergency room earlier.
And I think this is the kind of
thing that doing these tests on the regular
and having done a lot of them to
evaluate the injuries and then how to treat
it is incredible. I had one of our
local, physical therapists shadow me in the emergency
room recently because she was just interested in
learning more about kind of the ER and
how things work and the value she immediately
brought in, in examining these musculoskeletal
kind of injuries. And then immediately kind of
giving patients the first steps in treatment for
it was so far beyond the care that
I'm providing. I could see just the value
we would have if we started involving physical
therapy earlier in the emergency room, especially given
the challenges of establishing those kind of follow-up
things. I think that it's a huge area
for improvement that I'm actively very interested.
Yeah. Yeah. For sure. And even in the
treatment section of this article, they spent a
considerable amount of time talking about discharge instructions
for patients. And some of the instructions that
are available online to give your patients that
include
treatment exercises,
physical therapy, maneuvers, and exercises they can perform
just because there's going to be a delay
in their follow-up care. I mean, nobody can
get into an orthopedist the next day even
if your arm is in four pieces. If
if you need it that fast, you gotta
be in the hospital. Otherwise, it's going to
be a while. And during that time, you
can get some pretty significant pain relief by
doing these maneuvers.
And, you know, short of the patient Googling
it themselves, having some focused discharge instructions that
come from you become very, very important.
Alright. Let's talk about imaging. Everybody gets an
X-ray.
No. I'm just kidding.
There is a guideline for who should get
an X-ray. There is the Ottawa Knee Rule,
which has been studied, prospectively validated.
And
when it comes to the Ottawa knee rule,
doctor Eckler, which of the following findings warrants
obtaining a knee X-ray? So according to the
Ottawa knee rule, which one of these would
warrant getting the X-ray?
Pain with passive range of motion,
inability to flex the knee to 90 degrees,
pain with patellar compression,
or presence of a mild knee effusion.
It's not the knee effusion.
I'm trying not to look at the table
right now. I'm trying to just remember it
from memory.
Give me the first one you said one
more time.
Pain with passive range of motion. No. Inability
to flex the knee to 90 degrees.
No.
Pain with patellar compression
or presence of mild knee effusion?
I think it's pain with patellar compression. Okay.
Final answer. Yes.
Okay. So the Ottawa Knee rule actually lists
inability
to flex the knee to 90 degrees as
one of the criteria to obtain an X-ray.
There are only five criteria at least. And
if you have even one of these that
is positive,
then the Ottawa knee rule cannot be applied
to exclude X-ray. It doesn't mean you have
to get one. It just means it's like
the perk rule. You cannot exclude the need
for an X-ray based on the Ottawa knee
rule. And those criteria are age greater than
or equal to 55 years old. That's a
good one. I don't think as long as
they're cut off. Yes.
As soon as you get there, then you
just gonna get some x rays.
Isolated tenderness of the patella with no other
bony tenderness.
You gotta give me credit for patella compression
there. You gotta that's gotta give me Yeah.
Yeah. That again, poorly written question. I totally
agree.
Tenderness I'm challenging I'm challenging that one with
the the proctors.
Tenderness at the fibular head is another indication.
Inability to flex the knee to 90 degrees.
And lastly was inability to bear weight in
four steps
immediately
and in the ED. So this is kind
of one of those nuance things.
It's the ability to walk on your knee.
Limping is good. Limping counts, but ability to
put weight on your knee at the time
of the injury and in the ED. So
if they have even one of those criteria,
you can't completely rule out the need for
an x-ray. Again, it doesn't mandate an x-ray.
You just can't rule it out based on
the auto renew rule.
Sam, everyone within a fusion can't bend their
knee to 90 degrees. So, like, this is
around the time that I start they're getting
the eyebrow raise for me on this one.
But I I still respect the fact that
if you do this, you can cut down
in x rays. Because what only six percent
of x rays have a fracture, that's not
a very good diagnostic yield. As much as
I wanna defend the practice, you're right. Everyone's
getting an x-ray, and they're all negative. Yeah.
And if you're wondering what the sensitivity is
for the autoimmune rule, it's 95 to a
% for ruling out an acute fracture. Right?
So we're getting x rays. We're looking for
fractures, and the autoimmune rule can definitely help
in that scenario, especially in a busy emergency
department. You got somebody waiting for X rays.
You can go, ah, you know, you actually
don't need an X-ray, and let me explain
to you why. Because the time it's gonna
take for me to explain it to you
is still shorter than the time it's gonna
take for you to get an X-ray.
Alright. Another question.
Which imaging modality
is the most sensitive for detecting
an effusion in the knee? I should say
which of these imaging modalities is the most
sensitive. Here we go. X-ray,
CT,
bone scan,
or ultrasound?
Ultrasound. I'm an emergency doctor. I have a
pedagogy jacket. I'm here for the stereotypes. Let's
go ultrasound. Boom. You win, sir. Ultrasound.
The detection limit for an ultrasound in a
trained provider's hands is as low as four
milliliters.
Four milliliters. And the sensitivity and specificity in
diagnosing
tendon injury
with ultrasound
is a hundred percent.
You can't get any better than a hundred
percent. So that is
great evidence for the utility of an ultrasound
examination in a trained provider's hands, and that's
just using a limited protocol. So the orthopedic
surgeons will go with an expanded joint evaluation.
You don't even have to do that. You
can go, where does it hurt? Let me
look at the tendons in that area, and
then I'm gonna scan for a quick joint
effusion.
And you can detect as little as four
milliliters. That's pretty darn good.
And even more impressively, if you then use
the ultrasound while you're there to do your
arthrocentesis,
your your ability to actually get fluid out
of their knee goes up to a %
from an that ability. I think their success
rate was fifty five percent Fifty five. Did
it by landmarks. So as someone that does
a lot of landmark,
you know, arthrocentesis
and it feels a little you know, that's
how we did it back in my day
kind of about this. I think that I
need to really revisit my ultrasound skills on
this because as you said, to identify that
tendon injury, make their follow-up faster because you
can push that to ortho and say, look,
there's clearly a tendon rupture. You're gonna need
to fix this. And then to make sure
you get fluid out a % of the
time, you you can't knock that number. Yeah.
Yeah. And that procedure is described in the
article very nicely. There is a description of
how you use the ultrasound to perform an
arthrocentesis, but also how you use the ultrasound
to just examine a knee and the tendons
you're supposed to look at. I remember in
the era when I trained right as ultrasound
was starting to become popular during my residency,
and I got accustomed to putting in, you
know, central lines with no ultrasound guidance. So
if if I cannot grab the ultrasound machine
and I need to put in a central
line, not a big deal. But arthrocentesis
has always been one of those kinda fifty
fifty things. You know, you've got an effusion.
You know it's there. You just can't get
any fluid out, and ultrasound was a huge
help in that scenario. Huge help, because it
also allows you to kinda need to to
put that traction on the patella and on
the bursa and push that fluid superiorly, and
then you can see it with the ultrasound.
Now in that case, you're gonna need a
third hand, and you're gonna need an assistant
and say, okay. You push here. I'm gonna
use the ultrasound from here, and then we'll
find the pocket and drain it. But
definitely definitely going to improve your success rate.
Alright. Let's talk about CT. CT is available
to us in the emergency department. But in
general, if there's no history of massive trauma
to the joint, this is not going to
be a helpful test. It's not gonna help
you detect small or moderate effusions,
and it's not going to be any better
than X-ray at identifying tendinous injuries.
MRI is really what you're looking for, and
MRI is generally, we say, not available in
the emergency department. I mean, in an emergency,
sure, there's an MRI machine in the hospital,
but you're not gonna use up those resources
for a knee injury, and that's gonna be
a huge time delay. So
CT is there for traumatic
knee injuries if you think you're missing something
bony. Otherwise, it's not a good modality for
imaging, for knee pain.
I and I would say, I think that
there's always the caveats to these. We had
a patient who came in five times the
emergency room for knee pain over the course
of a few months on her fifth visit,
her x-ray really looked abnormal to me. And
I went and ran it by our, our,
or so, you know, radiology folks. And they
said, yeah, that, that is really suspicious. Like,
I I think I could see why they
read it as negative before, but it just
really there's something there. So we admitted her
for an MRI because she really had poor
follow-up and and no real opportunity to to
get an outpatient follow-up. And her MRI looked
like an osteosarcoma, and we managed to basically
start arranging treatment and and outpatient follow-up with,
you know, an orthopedic cancer specialist out of
town. And I think if that hadn't happened,
that would have, you know, gone on for
another couple of months before she really got
the care. So if you're curious, keep asking
questions about these things, and there is time
to deploy these modalities or to to keep
people overnight in the hospital to get things
figured out and make sure you get the
next step going, especially when they've had multiple
visits and and things aren't really getting getting
worked up. Yeah. Yeah. Great plug for the
ops unit. That's a great ops patient right
there. For sure.
Alright. Let's talk about labs. So when it
comes to trying to differentiate
multiple things that might be going on, we
can always get labs, and the labs
might be helpful.
Specifically, if you're thinking about a septic knee,
that's that's really the only reason why you
might get labs. So let's talk about some
of the labs that you might get. People
generally will get a CBC.
They can get a erythrocyte sedimentation or ESR,
and they can get a c reactive protein
or CRP.
And then blood culture, certainly, if they're febrile,
you're gonna get blood cultures, or if you
know they have a septic joint, you're you
can get those as well. But when we're
specifically, when we're talking about CRP,
a cutoff of
20, that's milligrams per liter, had a sensitivity
of about ninety two percent for identifying disease.
If you use a cutoff of 15, that
sensitivity actually goes up to ninety eight percent,
so even better. Now you're you're gonna get
a lot of false positives in that scenario,
but still, it has decent sensitivity.
For the ESR, you get 98%
sensitivity if you use a cutoff of 10
millimeters per hour, or you could use a
cutoff of 15. That sensitivity drops a little
bit to 94%. So still, there is some
utility for these tests if you're entertaining a
septic joint, but the most sensitive test is
going to be getting the fluid and sending
it for analysis.
And on that note, table five on page
11 shows you the normal
arthritic
inflammatory
and septic features of synovial fluid when you've
performed that arthrocentesis.
So that's talking about clarity, color, white blood
cell count,
polymorphic
neutrophil
percentage or PMN percentage,
the culture results,
and the joint lactate level. Now when's the
last time you sent a lactate level for
our joint fluid?
In defense of our lab testing setup, when
you do our ED common, you know, fluid
orders basically for aspirating anything,
LDH and lactic are there and I tend
to order them fairly regularly, but only because
I'm set up for success by a good
lab ordering system. And I think that the
case for this is that you should have
that option there for you, or have it
preselected for your arthrocentesis
so that after you complete a complicated challenging
procedure and you get success, you don't fumble
the ball on the one yard line by
not ordering the right tests because you're in
a busy ER and you're juggling
10 balls that are all on fire and
trying to keep things under control.
Yeah. Perfect. Way to plug the order sets.
Really, that's that's something that can be prebuilt
for you, so you don't even have to
think about which test or which one of
these you need to order. All of these
should come across along with crystals and the
LDH.
Interestingly, the authors have a systematic review they
quoted from 02/2011
that looked at joint lactate levels. If you
had a lactate level greater than 5.6
millimoles per liter, your positive likelihood ratio was
2.4,
pretty significantly high. I thought it was pretty
funny that they also said that same systematic
reviews says if you have a lactate level
greater than 10, your positive likelihood ratio
was infinity.
So pretty pretty safe that number, infinity. You're
you're good at that point. The diagnosis is
established. You can tell also you're sure. Time
to give the antibiotics.
Now now you're now you can give.
I do think it's important to reference this
table when you're looking at something that might
be inflammatory versus septic because that's really always
the question for me. It's not so much,
you know, is this normal? Is this abnormal?
It's is this inflammatory, or is this actually
bacterial? And do we need to then, you
know, get ortho involved in antibiotics and surgical
washout?
So the inflammatory cutoffs are anywhere from 200
to 50,000 white blood cells, and then the
septic cutoffs
vary depending
on the patient. So if they have a
prosthetic knee joint, greater than 1,100
is indicative of a septic joint. If they
have
50,000 or more, the likelihood ratio is seven.
If they have 25,000,
the likelihood ratio is two point nine. So
there's this kind of overlap with the inflammatory
white blood cell count, and that's where you
then also need to rely on some of
your other tests. So you've got your polymorphic
neutrophil percentage rate or your PMN rate will
be higher in septic arthritis.
Both will appear yellow and cloudy, so that's
not really gonna be much help to you.
Sure. There's about a fifty percent positivity for
cultures for joint fluid, but you're not gonna
wait for that in the emergency department.
Your LDH level will be greater than two
fifty in a septic joint, so another benefit
of getting that test. And then there should
not be any crystals present.
And so you really need all of these
to try and differentiate
between septic arthritis versus inflammatory unless your white
blood cell count is super high.
And I I think that was the takeaway,
just that you're not gonna be sure at
the end point where you get your cell
counts. So there's there's a good time to
send the culture, get all the labs, and
then give the antibiotics and let it play
out in a day or two as those
cultures
grow. Alright. Let's get into some treatment real
quick. So
what is the first line medication for treating
an acute gout flare? Here we go. Ready?
You got five options. NSAIDs,
acetaminophen,
allopurinol,
colchicine,
or methotrexate.
Oh, nice fifth one. Yeah. You like that?
I'm gonna go with NSAIDs, but can I
tell you this article made me question
whether or not I need to be giving
more Celebrex in my practice? And I need
to look at the cost of Celebrex because
I think it's gone generic. And if it's
cheaper,
I bet it's gonna cause less GI problems
than the Aleve that I'm regularly writing for.
I guess I should say naproxen because we're
using generic names here. Yeah. Yeah. Well, obviously,
you are correct, and you're correct on both
of those things. The Oh,
the the treatment with NSAIDs is definitely the
first line for inflammatory or gout arthritis.
And and, yes, the longer acting ones are
less GI toxic, and once a day dosing
is certainly better. You know, you can use
Tylenol, but it doesn't really have any anti
inflammatory properties. Allopurinol
is used more for chronic gout, not for
acute flares. Colchicine is the second line agent
because of GI side effects, and methotrexate, we
use for rheumatoid arthritis, not gout. So not
an ideal choice in case you're wondering.
I also found that so often people are
on blood thinners or have a reason they
can't take NSAIDs,
but I found that I've been ignoring topical
NSAIDs for those patients. And I think that
that's something that I need to deploy more
in my therapy because
you can't use them centrally. Like it can't
work on back pain or on neck pain,
but for elbows, wrists, knees, ankles, topical NSAIDs
are very effective. I think should be something
that we're looking more into giving people, especially
when they don't have a, you know, an
ability to take oral ones.
Yes. Yes. Absolutely. And the authors actually mentioned
that there are a few randomized controlled trials.
One of them had almost five hundred adults
with moderate knee osteoarthritis,
and they compared diclofenac one percent topical gel,
which did show a significant decrease in mean
pain score. So, yes, topical
can be effective and come with decreased systemic
side effects,
like the gastrointestinal
side effects. And so definitely an option there
for sure.
On the treatment side,
which treatment
is the most effective? So most effective for
a long term management of knee osteoarthritis.
You ready? Here we go. Five choices, NSAIDs,
acetaminophen,
weight loss and exercise,
corticosteroid
injections,
or opioids.
And if you say opioids, I'm gonna slap
you. I'm I'm gonna humbly go with choice
c, weight loss and exercise because I'm pretty
sure that I've picked this post everything. That's
absolutely
true.
Yes. The author specifically say that a combination
of dietary changes and exercise
can improve physical function, lead to weight loss,
and improve overall mobility,
and is better than all the others if
it can be achieved. Right? So, obviously, that's
going to take some time. That's not an
immediate treatment, but certainly something that should be
discussed
with the patient and started. So here's your
exercise regimen. Here is your physical therapy exercises
we want you to perform,
and here is your prescription for a long
acting NSAID or your topical NSAID for sure.
Alright. Again, still on the treatment side of
it,
many of us are fond of giving people
knee immobilizers.
And I'll say many of us, myself included,
have used these for all kinds of traumatic
and persistent knee pain, and you're wondering, okay.
When is it you know, I just give
them a knee immobilizer and have them follow-up
and give them some crutches. So the question
is a knee immobilizer
is most appropriately used in which of the
following conditions?
Osteoarthritis,
the telefemoral
pain syndrome, that's the anterior knee pain,
quadriceps tendon rupture,
iliotibial band syndrome,
and prepatellar bursitis.
So this is a knee immobilizer.
Yeah. Now if you're wondering if you're listening
and you've never used an immobilizer before, it's
not that little
strappy
knee wrap that you get at a store
or the one that has a little opening
for the patella with a couple of Velcro
straps. It is a long device
that covers,
from about the proximal thigh down to about
the distal shin and has two metal bars
that run on the inside and the outside
and prevents you from being able to flex
your knee at all. So you can still
weight bear, but you kinda do that peg
leg walk. And in most cases, you need
a set of crutches as well to go
along with it.
So which are the following conditions? Osteoarthritis,
patellofemoral pain syndrome,
quadriceps tendon rupture,
iliotibial band syndrome, or prepatellar bursitis?
I'm really only using them for quadriceps tendon
ruptures,
so that's my answer.
Alright. And you are correct, sir. The immobilizers
are indicated in any kind of extensor mechanism
injury like a quadriceps tendon rupture.
Patellar fracture
counts.
A patellar tendon rupture also counts.
And so if they have one of those
mechanisms that has kinda taken away their ability
to extend their knee, then,
sure. Absolutely.
Displaced tibial plateau fractures?
Yes. You could certainly do that. And and
it also does say first time patellar dislocations.
So if this is their first one and
there's a lot of edema there and they
can't flex their knee afterwards and there's significant
pain, sure. This can help and provide some
stability to the joint and allow the,
edema to start to go away for a
couple of days.
But there is significant
morbidity associated with placing somebody in a knee
immobilizer, especially if they're elderly. So the reason
why this was even discussed in the article
there on page 13
was
to bring up the point that knee immobilizer
is not benign, and they shouldn't just be
handed out like candy to people who are
elderly who might have
mobility constraints to begin with because now they're
gonna be even more
apt to falling and injuring themselves.
And oftentimes,
using crutches if you're elderly is almost impossible,
and now we've thrown them in a knee
immobilizer. So just be super careful about who
you give this to and making sure you
have the right indication for it.
Also worth looking at a video for how
to actually put them on because it's challenging
to fit these to people, sometimes people that
are obese or just people that are are
just, you know, uncomfortable and in pain. And
I've seen a few orthopedic surgeons put them
on where they literally take them down, like
all the pieces apart and then wrap them
and then put the, like the support metal
rods on and then put the Velcro on.
And it's impressive to see it done well
because it reminds you that
doing them correctly and fitting them correctly is
a skill. And if you develop that, the
patient's gonna be more successful with it.
Great point. Great point.
There is a discussion in the article about
corticosteroid
injections and when they might be indicated.
That's not something I typically incorporated into my
emergency department practice. You ever had to get
one of these?
So when I was running a little emergency
room in Colorado, everyone used to request that
they could get their their allergy shots every
year. So they would come in for these
catalog shots. And I was always really confused
by, like, is this a thing? But it
was just local practice. Like, that was just
what everyone got, like, during certain allergy seasons
of the year. They'd get a catalog shot.
Their allergies wouldn't be as bad. But then
there was a challenge in getting orthopedic follow-up
in that community. And there would be older
people that would come in with chronic knee
pain that hadn't had a steroid injection in
six months or eight months or a year,
and they'd really be hurting. And I would
do their steroid injections. And I kind of
figured out how to mix, you know, some,
some catalog and some, some lidocaine. And it
was impressive how much it helped them. And
it was a skill that I didn't think
was that hard to develop. So I think
that if you can get them good orthopedic
follow-up in a reasonable time, that you should
leave it to the orthopedist, that's gonna manage
them going forward to kind of decide on
when they need steroids and when they don't,
and to kind of manage the risks and
benefits. But if it's been a long time,
six months or a year, and they don't
have access, and they're really someone that's gonna
benefit from it, I think it's worth considering
the ER. If you have the bandwidth and
if if you you feel comfortable, give it
a shot. Good. There were three points that
the authors made about these steroid injections if
you're going to give them in the emergency
department, and they didn't recommend against it, mind
you. So if you want to give them,
you certainly can. Three points they made. One
is make sure that your patient doesn't have
some kind of treatment plan with an orthopedic
surgeon already established.
Second, they can only get these shots one
every three months or so to avoid the
potential for degeneration of cartilage. And so you
do have to know when their last one
was, has it been three months. And third,
giving one of these shots will preclude them
from getting joint replacement surgery for three months.
And so if they know, hey. I'm seeing
an orthopedic surgeon and I've got you know,
they may tell you I've got an appointment
set up, but that appointment is actually to
have their knee replaced. And if they weren't
specific about that, then what you've just done
is reschedule their knee replacement surgery by giving
them a steroid injection. So be careful. Make
sure you get an accurate history.
And, otherwise, there was no other significant contraindication
or side effect to giving these in the
emergency department.
Okay. And that's all the treatment for osteoarthritis,
chronic knee pain, perhaps even acute knee injuries.
Let's talk about some of the treatment for
trauma.
So traumatic knee injuries, you've you've gotta be
careful with because
knees can dislocate and relocate spontaneously
after a trauma.
And it's important to have a high suspicion
for that because that mechanism can cause injury
to their popliteal artery and popliteal artery dissections.
The patients that come in with traumatic significant
knee pain,
swelling, effusion, discomfort,
you really wanna be cautious and really check
their pulses, you know, a couple of times
to really get a sense of whether or
not there could be vascular injury. And even
if they have good pulses, but you've got
a high suspicion, that is a good time
to do a CT, but a CT angiogram
of that leg to look at the blood
flow through that injured
leg. Because I think that that's going to
allow you to catch things that are challenging
diagnoses to make. But if you've got a
high suspicion for a knee injury and a
potential dislocation
and they're having pain and their pulses aren't
as good on the injured leg as the
other, don't hesitate to take that knee to
CT and get a CT angiogram
because that's gonna help you get them to
the vascular surgeon they need, not the orthopedic
surgeon.
Yeah. Yeah. Great advice.
And on that note, that is all that
we're going to cover today. There is more
in this article. It is filled with information
about patients with prosthetic knee joints, about tai
chi and physical therapy for osteoarthritis
and so much more. Don't forget to go
look at the images for ultrasound scans of
the knee, read through the processes for how
to perform ultrasounds of the knee and how
to do ultrasound guided arthrocentesis,
and, of course, don't forget tables, the multiple
types of physical exam maneuvers you can perform
to help make the diagnosis, the differential diagnosis,
the historical questions to ask. There's just a
bunch in here. I just wanna say thank
you to the authors for writing an outstanding
issue. This is the Emergency Medicine Practice March
'20 '20 '5 issue. And if you're a
subscriber, don't forget to go online, take your
CME test, and get your CME for completing
that issue. Thanks again, everyone. Until next time.
I'm Sam Hsu. I'm TR Eckler. Stay safe.
Be careful playing that pickleball.
Love the pickleball.
And that's a wrap. Thanks for joining us
for this episode of Amplify. I hope you
found it informative, and I wanna remind you
that evmedicine.net
is your one stop shop for all of
your CME needs, whether that be for emergency
medicine or urgent care medicine. There are three
journals. There's tons of CME. There's lots of
courses. There's so many clinical pathways, all this
information at your fingertips
at ebmedicine.net.
Until next time, everyone. I'm your host, Sam
Ashu. Be safe.