Ep 61: Patellofemoral pain CPG: 6 factors to consider for better diagnosis, with Dr Christian Barton (Part 1 of 2)

[Music] Hello and welcome to JOSPT Insights, the podcast that aims to help you translate quality research to quality practice. I'm Clara Don, the editor-in-chief of the Journal of Orthopedic and Sports Physical Therapy. It's great to have you listening today. [Music] Treating knee pain, particularly patella femoral pain, isn't always straightforward. With multiple avenues for assessing and addressing impairments in our patients, we decided to contact Dr. Christian Barton, co-author of the 2019 Clinical Practice Guidelines on Patella Femoral Pain, to come onto JOSPT Insights and help us optimize our treatments. Dr. Christian Barton is a postdoctoral researcher at the University of Melbourne and Latrobe University, with his primary research focus being improving knee pain and injury management. He's also clinical director and co-founder at Complete Sports Care, located in Melbourne, Australia. My name is Dan Chapman. I'm a US-based physical therapist and owner of Chapman PT in Baltimore, Maryland. And I am Chelsea Kumin, a physical therapist and athletic trainer at True Sports Physical Therapy in Baltimore, Maryland. Thank you so much for being on the podcast. Thank you for taking the time to share your knowledge on this ridiculously complex and important topic. Thanks for having me, Chelsea. I'm looking forward to chatting to you about it. So we are digging into today the CPG, the Clinical Practice Guidelines of Patella Femoral Pain, that was published in September 2019 in JOSPT. Christian Barton is one of the authors on that study. So also, thank you for putting in the time and effort of this 95-page document that we have regarding Patella Femoral Pain. And so our goal today is to try to just boil that down to just a mere 25-minute podcast episode where clinicians can grab the most important pieces from that CPG and take it into their practice. So, Christian, do you mind if we start with just the very basics of defining Patella for moral pain? Yeah, sure. So if we go back really simply, Patella Femoral Pain is just us using fancy Latin terms to describe knee pain or kneecap pain. So, Teletel Femoral, it's the female or the fine, and Patella being the kneecap. So I talked to patients, you've got kneecap related pain. I think that's what we need to start to think of it and not make it too complicated. It's a diagnosis of exclusion. So typically, the diagnostic criteria relate to panjuring activities that load the Patella Femoral joint. And so there are things like squatting, stares, running those types of activities. And so if we've got pain peripatela or retro-petela, so in and around the kneecap, with those types of activities, that starts to lead us down the path this might be Patella Femoral Pain. And then we need to exclude other potential causes of anterior knee pain. So the common ones being Patella Tennopathy, which you might exclude through Pell Patient, the other common thing I would look at is maybe if we're doing resistance static contraction, where the pain might emanate from when in terms of range of knee flexion. So if resistance static contraction is painful in deeper flexion, so really deep flexion, that's typically indicative of a Tennopathy, whereas as you go towards more terminal extension, Patella Tennopathy is not often that painful. It's more related to Patella Femoral joint will often be painful through to that terminal extension range. Now that the caveat to that is if there is Bionara or Dima associated with Patella Femoral Pain presentation, that can sometimes also be painful in deep flexion as well. So that's kind of the diagnosis and what we're dealing with. And then, of course, we need to consider other things like miscal pathology and ligamentus injuries and we all know our tests we can do in the clinic to assess those and excluding that they may not be. We're later than the other thing to consider is we often see Patella Femoral Pain alongside other knee pathology. So we might have a history of an ACL injury and then we've got subsequent Patella Femoral Pain, or we might have a history of Patella Tennopathy, which then due to the conditioning and and dishoost, we end up developing the Patella Femoral Pain condition as well. The definition of it as just it's a diagnosis of its pain in the front of your name. Pretty much. Your Patella Femoral joint. No, that sounds like a lot of people that walk into a typical outpatient clinic, no matter like, kind of who you're seeing and what aid group. So are there risk factors for experiencing Patella Femoral Pain? Yeah, sure. So you touched on something that is a common presentation and I guess the point to make around that is, estimates are close to what in four people will have Patella Femoral Pain at some point in their lives. That's quite high of people. So this is young adult, so aged 18 to 40. And there's a nice review by Ben Smith, which sort of summarises all that literature. Very common in adolescence as well. And that's important to point out. And we probably see it commonly in athletic populations also. So looking at people maybe playing sport or also things like basic military training. So in terms of risk factors, it really is a difficult challenge in research to identify risk factors. Having reviewed the literature in this space and also been involved in some work, which we currently have under review, it's really hard to identify a risk factor that would say these persons are more likely to develop pain. So when we look at it, we commonly think of things like hip weakness or knee weakness might be a risk factor for developing pain. And if we talk about weakness, then actually some research in younger athletic populations indicates that some arm with a stronger hip might be more likely to develop pain. So completely contrary to what you would expect. If we look at the quadriceps, there is some really limited evidence in military populations that quadriceps weakness or knee extension weakness might be a risk factor for developing pain, but we don't see that same evidence or same data in the general population. If we look at other factors like everyone in PT practice gets obsessed with knee vellus and thinking about cue angles and these types of things. So both statically and dynamically, we don't see that cue angle and evellus is a risk factor for developing patellar fibrill pain. It doesn't come through as being a factor that would lead someone to be more likely to develop pain. And we have things like maybe more systemic things like BMI and excessive body weight. And again, when we look at the research, that doesn't really come out as being a risk factor, at least not a strong risk factor for developing pain. And then the common thoughts are perhaps things like excessive loading or doing too much too soon, etc. And even when we look at the literature related to that, it's really not clear that we can say, this is a key risk factor for developing pain. BMI canically, even if you were to do a running assessment of someone, there's very limited evidence that say excessive hip aduction may be a risk factor for developing pain. There is one study produced by Brian Norrin a number of years ago in a female population, which indicates maybe in that female population more hip aduction makes them more prone to developing pain. But it's only a few degrees difference. So in short, earlier risk factors we can use clinically to say this person's more likely to develop and screen. We probably really can't do that very well. And so I think what happens, though, is that doesn't necessarily mean that all these factors aren't considerations for treatment. So when we use hip as an example, we see once someone's had patellar fibrill pain for a period of time, they may have more hip aduction during activities. Importantly, they've probably got hip muscle capacity impairment. So we talk about not just strength, but things like muscle power rate of forced development. So that ability to generate force quickly, which is going to help to support the knee. We definitely see quadriceps weakness and quadriceps atrophy as a result of prolonged pain. But we also start to see things develop like pain sensitization. So they become more sensitized to pain. We also see things start to develop like fear of movement and canesia phobia. And all these things weren't identified as risk factors with developing pain, but they've become a problem for that person once they've had pain for a prolonged period. Sure. So it sounds like there's there's not a set of actual risk factors that are consistent. It's more so we've found a lot of things that aren't consistent, which is most things age, BMI, actual mechanics, like including that of alga's angle. There's some sort of quad and hip weakness component to it, but it doesn't necessarily translate into everybody with weak hips is going to end up with patellarph moral pain or everybody with patellarph moral pain has weak hips. So it sounds like our exam is going to be pretty important then in figuring out patellarph moral pain. Is that correct? Yeah, I think so. And I think when we talk about our exam as physical therapists, we often focus a lot on the physical. And so our exam shouldn't just include the physical. So yeah, we need to assess for movement patterns that we might consider related to that person's pain. And if we're seeing movement patterns, let's use the dynamic alga's concept. And if we modify that or cue someone to change it and improve their pain, improve their symptoms in that short term and immediate term, that might be a great strategy that we go down and we use. We might assess quadriceps muscle capacity or hip muscle capacity. And we can do that through things I can have dynamometry. In my clinical setting, I use a lot of 10 repetitions, testing using cable machines and leg extension machines and leg colon machines. And if we're finding key impairments, either that be comparative to an asymptomatic side or just general weakness that we can identify then we can certainly maybe indicate that that might be more important intervention for that person. But the other thing we need to pick up on with our assessment in that clinical setting is how fearful is that person of loading and is there some fear related to it that might be driving their symptoms. And so a little clinical test I'll often use is just put a small step. So not a proper step, just a small step one that likely makes no sense that it should cause any structural damage, right? It's just a tiny step. And some people look at that step and then they start turning before they even step on it. And so straight away, that's a real nice objective test of saying this person is really worried and fearful about danger in me. And we know that can drive their symptoms. We can also use screening tests like the scale and short form of re-bro which are the nice tools to use to pick up on some of of the more psychological factors that might drive their symptoms. And then we probably need to then dive a bit deeper and ask some questions about it. Are you worried you're going to damage your knee? And then building on from that going to more, I guess clinical diagnoses of psychological factors that are not necessarily directly related to condition, but certainly influenced by the condition on my influence pain. And that is things like anxiety and depression, understanding those things, getting a feel for the person's lifestyle. So are they eating a good diet or a poor diet? We know that can have effects on systemic inflammation, which would obviously influence their pain. Are they getting enough sleep? Are they just generally looking after themselves? And sometimes these physical things that we focus on are the big rock for them. It's actually all these other factors. And so I think it's really important for a physical therapist to be acutely aware of all these things and do a really thorough assessment. Otherwise, if we just start smashing the quadriceps and hit with exercise and don't address these other things, we probably won't get very far. Right, that's a nice reminder to be like a well-rounded clinician and actually care and actually ask about all of those things that really impact healing, like nutrition and sleep. They're going to make a huge difference and not just focusing on that anterior knee and nothing else. And if we just build a little bit on the psychological components of it, if we look at something like pain and disability, subjectively measured, we don't see very good relationships between muscle strength, so knee and hip muscle strength and pain and disability. They're not well related at all. But we do see relationships with canesia phobia. So when we use a scalao tampa and we measure that, we see quite nice relationships, not nice relationships, but reasonable relationships between how much fear someone has of activities and fear of pain and fear of damage and how much pain and disability they have. So that's really, really important. What I want people to understand and disentangle as well, though, that doesn't mean that getting someone stronger with the telephone or pain doesn't matter. Because if we look at the research and the literature a little bit further and especially in an athletic population, we see relationships between muscle strength and muscle power and muscle rate of force development, the hip and knee and their functional performance capacity. So how far they can hop, for example, how well they can control when they land. So their performance ability is impacted by those things and if their performance ability is impacted, then of course, similar like to pain with certain activities as well. So it's quite complex when it all comes down to it. It's simple, just the front ear near her, but it's a lot more than that. So in the CPG, it breaks down into just, it seems like to make it a little bit easier for clinicians to grasp the four categories of impairment that can kind of help guide treatment. And so it kind of helps, okay, you go through your exam, you can find, you can kind of put somebody in four different categories and that can guide how you actually choose to treat. So do you mind going over those four and maybe some key hallmarks that you find, whether in the subjective or objective part of the exam? Yeah, sure. So if we sort of break them down, the four that we're putting there, and this is not because these are the only four things that consider which we've kind of been talking about, but these are four things that are commonly discussed in literature, commonly researched and we can use as a guide. And so overuse or overload to that concept of someone doing too much too quickly. I mentioned before, there wasn't a lot of evidence that suggests that there's a risk factor there, but it's really having a look at someone's training load. And we know both anecdotally and also there's a little bit of limited research in running populations that if we can control how much someone does and they're not doing too much too quickly, that can help reduce their symptoms and sometimes in an acute setting. So if someone hasn't had pain for a very long, that might be the key reason they've got pain and they're still having pain in the short term and if we control those things. So we dial down how much exercise they're actually doing. That's all we need to do. And so that's a really important subgroup that we sometimes identify. Then the other thing we, the next one we have is muscle performance or muscle capacity. And you can think of muscle performance and capacity a few different ways. You can look at things like muscle strengths, so they build a generate force. You can look at muscle endurance, so how long that force can be generated for. And we can look at muscle power or how quickly that muscle muscle force can be generated. So muscle power becomes really important for high level activities like running and jumping and landing. Whereas arguably, muscle strength might be more important for lower level activities. Now to talk about some of our research, we see deficits particularly in strength, but more so in muscle power. So we see bigger deficits in muscle power for this population. And that's both in athletic and non athletic populations. So doing some assessments of that in your clinical setting, particularly at the knee and the hip, is going to give you a bit of guidance about what you might do treatment wise. The next category that's sort of outlined in the CPG is muscle coordination. So thinking about dynamic movement patterns, those types of things and so assessing some of those. And I talked before about maybe just seeing if we modify these movement patterns, does that help their pain? And that's a way that you might be able to identify someone where muscle coordination might be an issue. And if that helps, then you might go down that pathway in terms of your treatment. And then we have mobility impairments. So this could be hypomobile, so a really stiff hotel friend will join. Now I'm not going to sit here and talk to you and say we can measure those things reliably. Comes down to a lot of clinically experienced. And whether or not you need to do local interventions to address that we'll maybe get to that when we discuss trends. And then we also have things like ankle joint stiffness that might contribute to meaning that you end up with more load on the knee. So if you have less ankle dorsiflexion, then you have got less capacity for range of movement there. You might end up pushing into more pronation that might put more pressure onto your knee. It might be that your hip is limited in motion. And as a result of a hip-bing, and we see motion going into extension, well, I'd end up with more load on your interior knee during propulsion, because you're pulling off through using your rectus femoris, etc. So these things you want to start to assess. Equally, sometimes we have hyper mobility as well. So you might see someone who has greater foot mobility, more knee hyper extension. And these things might end up loading the joint more as a result of greater movement that's needed to control. Now in the CPJ and I had trouble grappling this as we're putting together such a massive document. As we've said, 95 pages. I didn't have strong input in this and I'm glad I did it because it would have been a nightmare to try and put together. We also need to probably consider a lot of other things that haven't been well researched and well looked at in this population. So the psychological factors as well, a whole range of other things, lifestyle factors. So I think that's really important to acknowledge. So I think move your clinical reasoning beyond those four factors that you read in the CPJ. And the other thing is putting them into those four factors or if we create six or seven or eight or 10, however many we have, that's probably what's cited to be because in most people and pretty much all people, you can have elements of each of those things. So you can have someone who has got hyper mobility and weakness. Someone else who got high polar mobility and weakness. Someone else who's got who's loading too much and a weaker someone who's loading too much and there's no weakness. But actually they're loading too much because the psychological factors they're running away from their life problems. So I think it's really important that we don't try and just box people into these categories and there's been research efforts to try and subgroup people with telephone and more pain. And so this is the treatment that would work for them. I'm yet to see any great research that tells us we can do that well. And I don't suspect we will see that research in the future. So that's what our humans are too complicated, I think. Yeah, absolutely. It starts to get philosophical, like you said. So the four categories are a good basically starting point. They're what the CP, that's what right right now that's what we have in research. That's what we can find as to as to putting people into four categories, which kind of make determining treatment easier, but we cannot ignore the fact that we're human and there's other things happening. Yeah, if you if you want to give yourself a clinical checklist, I think having those four things. And then I'd add a fifth one of psych, I'll probably six fifth one of psychological factors and then lifestyle factors. And I think if you if you have those six areas kind of a tick box, that yeah, I think I've fairly assessed and considering all these things, I think you do your patients justice. Those two check boxes could be added to literally any diagnosis. And I think it would make you a better clinician and your patients probably have better outcomes. Absolutely. And that is the first half of our two part episode with Dr. Christian Barton. On the next episode, we are going to focus on effective treatment interventions for helping your patients with betella for moral pain, get back to an active lifestyle, achieving their goals pain free. We'd like to send a big thank you to Dr. Christian Barton for sharing his wealth of knowledge with us and our listeners and to you. Thank you as always for listening to JOSPT Insights. Thanks for listening to this episode of JOSPT Insights. For more discussion of the issues in musculoskeletal rehabilitation that are relevant to your practice, subscribe to JOSPT Insights. On Apple podcasts, Spotify, Tune in, Stitcher, Google or your favourite podcast app. If you like JOSPT Insights, help others find us. Tell your friends and colleagues and rate and review us. To keep up to date with all the latest JOSPT content, be sure to follow us on Twitter. We're @jOSPT and Facebook, where JOSPT official talk with you next time.