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since the invite. Uh, so today we're going to do a little bit of basic science for the F. R. C s based on tendons, ligaments and meniscus. I, which are quite easy to come up in your exam. Um, this can relate back to an adult path station, a clinical station and basic sciences as well as pediatric, so it can come up literally, anywhere. And hopefully my slides work. So hopefully at the end, um, we should be able to discuss the structure of each of these tissues and what they're made of some of the basic principles behind the tissues, and then relate some of them to clinical scenarios. So, um, just so that I can test out if you guys can talk, uh, on this platform. Obviously, Um, what is a tendon? Any volunteers? Just don't meet yourselves and jump in the anybody. Hi, Sebastian. Thank you. So you say tendon or ligament? Tendon. What's the tendon? Uh, so a tendon is one of the dense connective tissues? Um, that's used to connect muscle to bone. Yeah. Nice people. Answer. That's all you need to say. Answers the question. You don't need to dig a hole for yourself by trying to throw in anything extra so well done. So all you need to say is that it's a highly specialized connective tissue, and it connects the muscle to bone. Okay, The main function of the tendon, as we've already said, is it's an attachment. It optimizes the distance between the muscle belly and the joint itself, and it gives some distance so that our joints are not really bulky, and so we get the best range of movement from them. It transmits the force, which allows movement of a joint, and it can be used as an energy store effectively as a spring. They're made up of cells, which are fiber blasts in the tendon, as well as Extracellular matrix, which has got multiple components. The first thing to be aware of is that it's type one collagen, okay, and that they're mainly made up of water, elastin and some ground substance, which is made up of proteoglycan is and glyco proteins. It's about an 80 to 20% split, which sometimes they might ask you in an MCQ question, and the project likens Give the tendon. It's compressive strength, and that's because project likens attract water and anything with the water has high compressive strength, and the type one collagen gives it its tensile strength. And a common F. R. C s question in a basic science fiver is to be able to draw approaching like can. So for those of you who have got some paper around, I'd like you to try and draw a pro to glycan for me, and then we'll talk through its structure. So I'm gonna give you all of about 60 seconds, cause that's about as much time as you've got in your f. R. C s to do it. And while you're doing that, the fiber blasts just to point out are what are producing the extracellular matrix within the tendons. And if you follow this structure for whatever tissue is made up of your notice that it's always cells and split into extracellular matrix, a proportion of water, a proportion of ground substance and some some type of collagen Yeah, it's a very similar pattern to keep using to help you remember it. So I'll give you 30 seconds more. Hopefully, one of you, at least, is drawing approach it like an or something that might resemble part of it. I'm just asking, uh, fill if, um, to invite someone to show their video, we might have to invite them on stage, you see? So that's probably the government's in. When we're using Zoom, possibly we'll see what happens. Does anyone have a picture that they'd like to show? You can say your name. If you do, then I'll invite you on screen on stage. Ashok, have you drawn one? He's been invited on the stage. And do they have to be verified before they can start showing their faces? Uh, okay. So I don't think anyone's maybe drawn one, so I'll show you my structure of approaching like, um and we'll talk through it. So, um, this is a hyaluronic acid backbone, okay? And coming off of that, you have a link protein, and with on within the link protein, there are three separate sub proteins G 123, and it's between the G two and G three that you have your keratin and chondroitin sulfate and an easy way of remembering which way around they are. Because the chondroitin ones are longer. Is that chondroitin is a longer word and has more letters. Okay, Each of these units is known as an aggregate can. And there are multiple aggregations coming off of a hyaluronic acid backbone. They're negatively charged and shut, so water is attracted to them. And the more aggregations you have, the more negatively charged it is, the more water you will hold. Okay. And that gives you compressive strength. So in the exam, you need to be able to draw this in about 60 seconds or less and talk while you're doing it and explain why it gives compressive strength. Does anyone know how collagen is formed? Anyone want to talk through college and production? If anyone hasn't gathered yet? My teaching is not didactic. I will be lying if I know it. That's fair enough. OK, Chondrocytes. Okay, we'll come to that, Iggy. Okay, so collagen is, uh, formed within the cell. So it has an intracellular part and an extracellular part of its manufacturing, and it starts off within the cell and has a primary structure, which is a try amino acid sequence where there is a glycine at every third triple sequence. And it's an otherwise a mix of higher hydroxyproline and praline in its secondary structure. It becomes a left handed helix, which is your one Alpha one chain. Okay. And at this point, this is exported out of the cell, and the rest of the production is in an extracellular fashion. So your tertiary structure is a superhelix that is spun right handed. And this is, um, collagen, as we kind of know it. This is your two alpha one chains and your one alpha two chains. And finally, it forms a quarter and restructure, which is your quarter staggered array. And this is basically the right hand is superhelix is now represented as a purple line. They're staggered, and they're connected together by these red hydrogen bonds. Okay. And this ultimately quarter staggered array is your microfibril of your tendon. Does anyone want to talk through the structure of a tendon? Okay, so, uh, the structure of the tendon is that you have a parity in on on the outer surface of the tendon and very closely within it. You have an EpiPen on which is this gray area, and then you have your bundles, which are made, which are yellow on this schematic, and they are all covered in an endotine on. Okay. Within a bundle, which is the tertiary structure of a tendon. There are fascicle, which are purple, and again the physicals are covered in the endotine on. And that's the secondary structure. And then you go on to have a primary structure which is known as your sub vesicles, which is blue. And again they're covered in the end, 18 on. From there, you have a fiber within the fiber. You have fibrillar. And within the fibrillar, you have microfibril, which we've already know is our quarters staggered array. Okay. So again, this is a structure that you need to be able to a drawing that you need to be able to do in about 60 seconds and talk through why you're in your basic science fiber. For example, Anybody know how tendons insert on to bone? I don't bite guys. Okay? Yeah. Awesome. Thanks, Omar. Yeah. So direct and indirect. Do you want to pick one? So tendons are indirectly inserted into bone via four different stages. Um, and the first one is the the muscular tenderness junction. And then you have the tendons, then form like, um, mineralized cartilage. And then that steadily goes into Mineralized college and then the mineralized cartilage then, uh, inserts within the periosteum of the bone. Yeah. So what Oman's describing here is this kind of increasing stiffness between the four zones. So from tendon too, and classified fibrocartilage to calcified fibrocartilage to bone. And this is an increasing stiffness as opposed to it just being tendon straight onto bone. Okay, there's a watershed area between the uncalcified and the calcified fiber cartage, which puts them at risk of injuries. Okay, indirect, um, in sessions is that between the tendon and the bone, there are these fibers called sharpies fibers, which are a mineralized collagen. Okay. And they pass through the tendon directly into the bone. And some people find direct and indirect a bit confusing, so you can use fibrocartilage fibro cartilaginous insertion for direct, and you can use fibrous for indirect. Okay, in the direct insertion we've already mentioned there's four distinct zones. They're generally, um, tendons that are inserting on a an epiphysis or a hypothesis. They're prone, their tendons that are prone to overuse, and their angle of insertion changes significantly during the range of movement of that joint and kind of most common ones that are injured with the rotator cuff and the Achilles tendon. And hopefully you can see in this picture that there's kind of four distinct stages phases of its insertion for direct here. And there's these farm kind of they couldn't bone fingers where they kind of trying to interdigitate the layers for indirect. You have the perforating mineralized collagen fibers, which are your Sharpie fibers. And generally speaking, these attendants are inserting at a metastasis or a diagnosis. So something like a doctor Magnus, for example. Yeah, um, and they don't really change very much at their insertion point in terms of their angle. So the difference between the tendon and ligament anyone wants to chip in before I start? So nobody else. Or is it just gonna be me? Go ahead, Omar. Pick something. Uh, well, composition, for example, the amount of elastin The ligaments have greater amounts of elastin, the rather than tendons, which makes them more elastic, Uh, and also in the micro structure, The way the the college or the collagen is arrayed in tenders, there are more parallel in a line of pull of the force, whereas in ligaments they are arranged in sheets which can be in different directions, which allows them to withstand stress in multiple directions at the same time. Good. Thanks. Perfect. So tendons are stronger. Okay. They have more collagen than ligaments do. And as Omar's just said, they generally are parallel to the pool. Whereas it's much more disorganized in ligaments. And that gives it Multiaxial stability. They transmit tensile forces, and they are less viscoelastic than ligaments. And they have less elastin. But there is one. Except there is an exception. If anyone can think of it again, is it just gonna be me? Is it the ligamentum UK or the spinal Ligaments? Yeah. So, um, the ligament of flavor is somewhat a misnomer. Uh, but it has got more lasting in, and it is yellow for that reason, because flavum is yellow in Latin. So, uh, we mentioned less viscoelastic properties. But any hazard anyone hazard to guess about what the viscoelastic properties are? I'm gonna show you three graphs and somebody can pick one if they would like to go on. Omar, I feel bad, because just me, but, uh, yeah, probably three types. History, PSA, stress, relaxation and creep. Uh, and they're all time related to just pick one graph and talk us through it. And if that's all right, uh, doing this on my phone, so I can't see one. But I talk about Greek, for example. So I think that's the center one, uh, which is a defamation over time with persistent stress. Um, and, uh, the effect of that is that you have a constant load on a material and that causes a strain and a change of it. If it's a defamation over a prolonged period of time, Have you got an example of creep? Um, I, uh uh, ligament is put under strain for a prolonged period of time. It may undergo defamation. Okay. Ashok, are you volunteering to talk through one? Thanks, Emma. Sorry, father. Did, uh so I'll take the last one. I think, um, I will explain the middle one. So the last one is a history. Uh, it's when we're loading The, uh, ligaments are attendants. Uh, the loading and unloading, uh, graphs are different because they lose their energy when they are offloading. Yeah, So the loading and unloading curves are different, and it's energy that is lost as heat because of internal friction. Thanks a shock. Anyone going to tell me about the first one, so Oh, yeah. Thanks so shock. The first one is the, uh, stress relaxation. Uh, when? Um when the, uh, material is, uh, loaded under constant when they're in a constant state all the time that, uh, record stress will be reduced or all the time. Good. Okay. So as you guys correctly said, uh, the first graph is stress relaxation. Second is creek, and third is hysteresis. In stress relaxation, you apply a force. There is a deformation that is constant, but at that level of defamation, the stress reduces within the tissue. Okay, An example of that is when you put in a femoral broach, okay, As you knock it in, there is an expansion in the cortex and you wait and that defamation stays. But the stress within it reduces. Okay, for creep, an example might be pentetic casting to apply a force IAEA load. And over that time that you apply that constant load. There is an increase in defamation. Yeah, So it's the principle of Ponsetto casting and history cysts. There's not really an example. It is just that it is energy lost as heat because of internal friction. Thanks, guys. Um, do you want to draw? If you've got some pen and paper, A stress strain, curve of attendant that we do this 1 30 seconds. Yeah. Can you bring it a bit closer to my, uh I couldn't find a black man. This is the only one I found. I don't know. I can see Ash. Ox, don't worry. Okay, So who else is showing me one. Iggy, Iggy, put the textbook away. Naughty. Uh, such a naughty boy. Okay, so we have a stress. We have stress. Strain, curve. Yeah. What's on your X axis? A shock. You're muted if you're talking to me. Uh, my X axis is a strain. And, uh, y axis is a stress. Uh, initially, when you're loading the tendon or ligament, we'll have the towing region initially. Then it'll have a linear, uh, co. Then which will reach kind like, kind of, uh, in normal stress strain covers the, uh, stress, but, uh, on the, uh, ligament and tendon, we'll say it's, uh, linear p linear curvature. And once, when it's once, when it it's a peeling, then there will be a small dips on the stress strain car where the, uh, the fibers will start failing because of the load. And then, uh, at the end, when the stress is at the maximum, then we'll have a P max where, uh, ligament will start failing completely good. Thanks, Asharq. So I kind of quit through as Ashok was talking then. Okay, so you have an initial towing in phase which you don't get on the stress strain curve when you draw it for, say, a metal. All right. And that's because your fibers in your tendon or ligament need to come out to length first before they can start changing length. And at this point, uh, the amount of force that is required or strain that's required to be able to produce them to uncritically is quite small. So it's a toe in area. It then goes linear exactly the same as your metal drawing would, and that's obeying hooks, law of proportionality. Okay. And this is occurring when the fibers are orientated with each other, and then we go through this period of sequential failure, which is, as each fiber is stretched and it starts failing. That corresponds to a dip when it gets to its maximum it then undergoes what we call necking. And that's where there is a drastic reduction in the cross sectional areas. There's enough fibers that are splitting that. Actually, the cross sectional area of the tendon, for example, is getting much smaller. And then ultimately, failure at the point which has no fibers left. So do you think the stress strain checker changes depending on how the tendon is loaded? The answer is yes. Leading question. Okay, so this is our normal one that we've just drawn. Okay? And then we have a curve here that I've shifted to the right and one that have shifted to the left. Okay, one. The one to the right is what happens when you repetitive Lee load at low level. And the left is when you, uh, load quite quickly. Okay, um, and when you load quickly, the tendon becomes stiffer, and it requires much greater force to be able to cause it to rupture. And with repetitive loading, it becomes less stiff and more compliant. And you can see here, for example, it requires much more stress to produce more deformity or strain. Yeah. Okay. So moving on on away from the stress strain curve. Okay, That's all you would need to know in an f r c. A station for stress, strain of a tendon or ligament. Um, need to be able to talk about the blood supply to attendance. So I've got two different types of tendons here. One is a parity non, uh, covered tendon. That's got a very good blood supply. Okay. And then there's this tendon, which has got sheaths going towards it. Uh huh, uh, which has got blood supply coming in a vessel within each of those Vernon Kyowa. And it's covered in orange because it's sitting in a sheath, and it's getting most of its nutrition from she through diffusion or osmosis. Okay, So which one of these, um do you think heals better one with Para Tina? Yeah. Why is what a shock. Um, because between the parity now and then the equity and there's, uh there's, uh the blood supply. Uh, blood vessels will be easily. Uh hmm. So in the in the sheath tendon, where the blood supply is coming in at very set areas, it only supplies one segment, so each vessel supplies one segment of the tendon. So if you you can see my cursor, can't you? So if there's a tendon injury here, the rest of that tender doesn't receive any blood supply, so it doesn't heal very well. All right, good. Thank you, Asharq. So Tendons Hill in a very similar way to be how we would describe bone healing and callous formation. So first there's a hematoma, followed by a period of inflammation and proliferation and then finally remodeling. Okay, we have chema taxes and fibrin deposition at the time of the hematoma, which takes, it happens in the first few minutes. Inflammation occurs over the first week, and that's where the fibroblast start to produce. Type three collagen. Note that they're not producing type one straightaway. Type three is your scar tissue. In that proliferative phase, there's more fiber blast, so they get more colleges really disorganized collagen, not the type that you would see in in tendons where it's nicely aligned. And this is a week scar tissue that's being formed in the same way that you're immature. Woven bone occurs in that very, uh, initial callus that's formed, and that happens over the first few weeks, and then in 18 months it starts to remodel. And that's where your body starts to convert the type three collagen or replaces it if you like with type one, which again is your more organized, stronger collagen. Um, so there are lots of different ways of repairing attendant and certainly in your Viber. You could be asked to draw out the typically or common ones. Uh, so you should be able to eat, be able to draw each of these tendon methods repairing attendant. Okay, um, there's lots of different ways of making it stronger in the same way that you could be asked to talk about how you make an expect stronger or how you make a nail. Nail fixation stronger. Uh, exactly The same question can come up in your basic science fiver or trauma of Iver, Um, for how you can make a tendon repair stronger. Okay, so the difference between these two is is that the one with the reduced gap? So as close as possible is the stronger repair, all right here. The difference is that the court super size has increased and that will make it stronger. And hopefully those of you that have started reading a bit further know that are to the power for is your second polar moment area and that, uh, that makes something stronger. So, like, a nail or an ex fixed pin. Okay, so the radius to the power for is exactly the same for a course future, cause it's a cylindrical structure. Okay, so bigger. Suture size, stronger repair. And here we've got the same suture side, same gap. But the one on the right here is stronger because there are four course futures passing through the center compared to two. And that is the difference between, um a Kessler and an Adelaide suture. You should be able to draw both of those out so the number of court passes increases increases your strength of repair. So just to summarize that from a surgical point of view making a gap smaller the different types of technique that you can use that effectively change the number. Of course you chose that. Past and your future size are ways that you can surgically improve your strength. And from a rehab point of view, we know that early range of movement increases the rate at which tendons heal and, uh, their strength. Anyone want to take a clinical station as of I like his practice doesn't have to be Oh, more or a shock. If anyone else is coming up to the exam and would like some practice. Do one of you boys want to go ahead, Omar, what do you think of the picture? So the psych clinical photograph of a mature adult, which shows evidence of most likely an Achilles rupture on the left hand side, there is a loss of the normal Achilles tendon with swelling and also loss of the normal, uh, plantar flexion of the foot. Hence, I would like to investigate this further and treat it as an Achilles tendon rupture. What special test can you do to examine this? Um, so special test be the Simons test where I would place the patient in that position with their feet overhanging. Uh, and I would grab hold of the gastrocnemius and lift upwards and see there should be a normal, uh, plantar flexion of the, uh of the foot. Uh, and if there is, um, loss of Simmons tests due to loss of the of the callous rupture of the due to a Achilles rupture, then then you wouldn't have that appearance. Yeah, so, um, there's something called Simmons Triad, which is looking at the position of the foot, which you describe nicely. So it's lost the inclination compared to the other side, um, you can feel for a palpable gap, and then you can perform Simmons test, which, when you squeeze the calf, you should see that there's plantar flexion at the ankle. Uh, and I'll tell you that there is no plantar flexion at the ankle in this one, and there's a palpable gap. Okay, the Simons test is positive for everybody when it doesn't produce plant affection. So it's a test that is positive for the pathology. Some people get confused over that. Good, uh, we talk about how to examine it. How would you said you'd like to manage them as an acute ta? How would you manage? How would you manage that? So it assess the patient who have taken a focus history looking at the mechanism of injury when it's occurred. Most importantly, uh, specifics in regarding the patient's comorbidities. Are they diabetic? Are they a smoker? And the social history Are they an, uh, an elite athlete or just work in a desk job um, my, uh, there are different ways to investigate it. Some re units perform ultrasound scan, but I think this is a clinical diagnosis. And if this was an acute rupture, uh, in a non athlete, then I would could treat this with functional rehabilitation according to a specific protocol. Okay, good. So, yeah, everything you're saying there's right, Omar, you obviously need to take a history and examination key things in the f. R. C s. To show high order thinking are to ask the risk factors of DVT because people are quite high risk for DVT after a t a rupture, given that it's the muscle pump. Okay, so and whatever you put them in, you're obviously going to have to consider giving them some, uh, Dodge pyrinyl your equivalent off. Okay, so some people could might say that in the initial stage in a and E, they would put the patient into iniquitous cost, uh, volar, but an equivalent of a volar backstab. Okay. In a quickness. Send them home with Dodge, Karen. And then, as you say, commence functional rehab, which is often with a removing wedges from a boots that they gradually get less queasiness and then a physiotherapy, and that usually goes over an 8 to 10 week period. Um, and obviously they need, um, prophylactic dalteparin for that duration, depending on other risk factors, whether they're appropriate for it or not. Good. How do tendons heal? So they heal in a, uh, depending on how. Which type of tendon is it supplied by synovial sheath, or is it supplied by a parity non, uh, the tendon supplied by operating on here? Better, uh, they initially he'll, uh, with, uh, fibroblast formations and collagen type three. Initially, uh, which is then subsequently, uh, substituted by collagen type one and a remodeling factor. But there are four generic phases, which is the hemorrhagic phase inflammatral phase proliferation and then remodeling. Good, Nice. When would you consider operating on an Achilles tendon? So if it was a delayed presentation, if it was an elite athlete, then I would have a discussion with the patient and go through the pros and cons of surgical versus normative management. Some studies suggest that return to functions quicker with surgery and then reduced rerupture rate. But newer studies doubt that and say that the the difference is not statistically significant patient to a high risk to failure of normative management. Uh, if they're non compliant, Uh, if it's an open injury, obviously I would repair it. If it was due to a lacerations, I would repair it. Um, those would be my primary reasons to, uh, go for an acute surgical management. Um, so hopefully you can all see how something that has been related to a tendon can be related into a clinical scenario. But I've also brought in a basic a bit of basic science talking about how tendons heal, so it's an easy way for them to pull it into a scenario. Okay, Good. Ashok, do you want to describe that photograph? Muted. Thanks. Uh, so the clinical photograph issues, um, there is a sequential casting, which is, uh, positive fasting for used for usually for, uh, ct. Uh, can you tell a particular virus? Uh, okay. Describe for me how upon settee cast works. The quantity cost works from the basic self. Uh, which is, uh, time time dependent plastic deformation. When there's a constant stress is, uh, played, uh, the quantity cost is applied based on this creep principal, um, initially, uh, the sequence of actions will be. It'll be correction of, uh, all right, hashtag don't worry. I will make you do the sequence. But if this is another example how basic sciences pulled in. All right, what are the other viscoelastic properties that tendons demonstrate? So the context demonstrate, uh, stress relaxation. And his stress is, uh, the stress relaxation is, um uh, the, uh, stress needed for, uh, maintaining the, uh sorry. The time dependent. Uh, yeah. Reduction in stress when there is a constant strain, that is stress relaxation. The other one is history says, which is, uh, the discrepancy between loading and unloading, Uh, stress, strain, curve. And this difference will be, uh, express with a lot of a lot of good. Good, lovely. So, again, this station could come up into your peed survivor as a lower limb, clinical or even in your basic science. Okay, I'm just trying to demonstrate to you how these kind of state how these kind of principles come up in the exam. All right, so we'll move on to ligaments. I've given you this one. A ligament is a highly specialized connective tissue, and it connects to bones. Okay. Nice and simple. Ligaments restrict joint motion and AIDS stability. Okay. And there is also a roll of appropriate reception, as they do have, um, nerve fibers within them. OK, so just to recap, tendons and ligaments have a slightly different s s curve, which I'll show you in a second. Okay. They have less collagen than tendons. They're less there. Um, collagen fibers are not as organized. They have more. Proteoglycan is, and therefore they have more water than tendons. Okay. And they're fiberglass, apparently are a bit rounder, but I don't think that's relevant. And they generally have a blood supply that is insertional. So their blood supply is at both ends. So ligaments have a much shallower stress strain curve, okay. And a much longer towing in phase. And and they recruit their fibers much more slowly. Okay. Which is why it's a longer curve. And the tendons have this very short phase because they don't take as long to an crimp. Okay. And there, as we already know, they're stronger than ligaments. Okay, so their curves are higher. This may not project particularly well. Uh, anyone want to take this? Where's Ignatius? Is there? Oh, I So I was on the train, the new close enough. Well, do you still want to take Iggy? No. Go ahead, Sebastian. All right, So, um, try and bring up the full screen. So basically got a p radiograph of a of a left knee. Um, I think the main fine. Obviously, I'd want to get a lateral view as well, but I think the main thing we're seeing is the flex superior to the fibula, which may be indicative of a a c l injury given to do you know what it's called? Second fracture. So sick on fracture. And then there's something going on into articulately there as well. All right. And you could say, as an additional kind of higher order thinking that this is X rays been taken with the knee in flexion. Yeah, you're getting a very good notch for you there. Thanks, Sebastian. So how do ligaments insert on to bone? Oh, he's gone. Oh, yeah. Um, so the same way as tendon Say that. That is what I was going to say. Um, but I forgot how to describe it. What are the two different? Broadly speaking, what are the two different ways so they can be Uh, certainly the directly or indirectly both ways both ways involved the the, uh, collagen being continuous with the, uh, with the periosteum of the bone via the sharp piece fibers. Yeah, So you can have direct where you have your four zones of increasing stiffness, and then you have your indirect where you have the sharpest fibers inserting straight into the bone from the from the tendon or the sigma. What factors influence healing of a tendon or ligament? Um, so factors can include both local and patient factors. Um, so similar to, I think, fracture healing of patient's of other systemic comorbidities. Um, diabetes. Um uh, uh, peripheral vascular disease. These will impact from the systemic point of view. Local factors. You can consider the distance that the ligament has ruptured the degree of rupture that's occurred. Um, yeah, no, they're all good things That the other thing that I would add here is there's joint stability. So say you do an MCL repair, but the rest of the ligaments aren't intact because, uh, multi leg, uh, the need still unstable. It won't heal. The MCL won't heal when you repair it. Yeah. So it's just another thing to bear in mind. Bottom again. Trauma of Iver Basic Sciences. Adult path could come up in your lower limb. Clinicals. Yeah, really? Common stations to come up. Well done. Thanks, Seb. So the meniscus we're gonna finish off on. Okay. It's a highly specialized Fibro cottage.