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 just wanna remind you that ebmedicine.net is your one stop shop for all your CME needs for emergency medicine and pediatric emergency medicine and even evidence based urgent care. You can find all three of those journals, the DEA MATE course, the laceration course, the abscess course, and so many other resources in in addition to the clinical pathways at the website and in the mobile app. So go there today, become a subscriber, and get all of
your CME met in one stop. And now 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.