Patella instability, BOAST and planning for treatment | Iain McNamara



This session provides medical professionals with an overview of the anatomy, biomechanics, and soft tissue restraints of the patellofemoral joint. It will discuss relevant imaging techniques, how to interpret them and guide clinicians on operative decision making. The session is designed to help medical professionals understand the patellofemoral joint, a forgotten joint which can cause major problems in exams. It will also provide an understanding of the anatomical structures and key areas of pathology. Join this session to gain an insight into the patellofemoral joint and its clinical applications.
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The PFJ and Principles of TKR

0930-1000: Principles of total knee replacement | Arman Memarzadeh

1000-1030: Sport injuries in elite athletes | Arman Memarzadeh

1100-1130: Break

1130-1200: Patella instability, BOAST and planning for treatment | Iain McNamara

1200-1230: Debate and journal club: to resurface the patella or not - NICE guidelines |

Chair: Iain McNamara. By Charis Demetriou and Madeline Warren

Lunch break

1330-1400: Principles of balancing and pitfalls | Jehangir Mahaluxmivala

1400-1430: Principles of alignment in knee replacements | Jehangir Mahaluxmivala

1430-1500: Debate and journal club: to HTO or uni in medial osteoarthritis of the knee

By Ignatius Liew and Luke Granger

1515-1530: Robotic knee replacements| Timothy Parratt

1530-1600: Cases: complex arthroplasty, FRCS shorts and beyond | Timothy Parratt

1600-1630: History of total knee replacements | Frank Foley from Smith and Nephew

Learning objectives

Learning objectives: 1. Describe common traumatologic and atraumatic presentations of patellofemoral joint dislocation. 2. Discuss the bony and soft tissue anatomy influencing patellofemoral joint stability. 3. Identify the role of the quadriceps, medial patellofemoral ligament, and the lateral retinaculum in maintaining stable patellofemoral joint. 4. Explain the mechanics of patellofemoral joint stability throughout range of motion. 5. Analyze the implications of a lateral release on the patellofemoral joint.
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Computer generated transcript

The following transcript was generated automatically from the content and has not been checked or corrected manually.

Yeah, fine. So, so basically, I mean, the P F J is not, it's not going to be a big topic in the, in the F R C s or probably not. If you get it, then you probably are doing really well or you're a bit unlucky. But basically, um what I want to do is really just do an overview of the anatomy because you're gonna get asked that it's an easy question. Free body diagrams I put at the back because it's the sort of thing that you can go away, draw the diagram, you've got to be able to draw and talk at the same time as you know, if the F R C S. So they're right at the very back and there's no point in me pretending to draw online. Um So have a look at those and work those out, but we'll talk a little bit about the mechanics. The important stuff for the F R C S really is easy ology and clinical assessment, the imaging that you might be given them, therefore how to interpret it. And as a G says, sort of both guidelines and operative decision making, we're not gonna talk massively through the operative technique because you won't be pushed on that tour. All right. So patella femoral presentations, I mean, there's a whole spectrum. You've seen shed loads of this um from fracture clinic all the way through to normal knee clinic. It's a, it's a, it's a spectrum between anterior knee pain and patella femoral instability. There are plenty of people who've got relatively normal needs. You've got bad muscles, you've got anti any pain that come in complaining of instability. And you do, you, you know, you're trying to get them to engage with physiotherapy and they're instability goes away. And then obviously, you've got people with pure patellofemoral instability, you've got no anterior knee pain, but as the as it gets worse, um as their muscles get weaker, they then develop and tyranny pain. So it's a mixture. Okay. Thanks Ziggy. So as I said, it's a common problem. Um and you know, we sort of all, no, you know, if an ACL comes in, you know what to do with that, you know how to image it, you know, what, what to do, you know how to send it on. But, but and if you look at the literature there, about 2000 ACL papers published per year, there are about 30 patella femoral papers published per year at, at Max. So it just shows, you know that this is very much a forgotten joint probably cause there's no money in it to be honest. That's probably the reason why, so the Americans don't get very excited about it, but, but it's still obviously causes a huge amount of, uh, huge number of problems. And the reason why you're interested in it right now is because it causes problems in exams. Okay. E G go for it. So broadly, two types of dislocation. One of which is traumatic. You've all heard those before, which is basically someone comes into fracture clinic, they've been walloped on their hockey field, someone, uh someone's hit them on the side of the leg, on the knee and the kneecaps popped out, often come back in again. Um Either spontaneously when the ambulance arrived and they've got a bigger fusion. Second would be something that's been dislocating for ages. They're often really young. Um They, you know, if you actually asked them, they've, they've come out multiple times, it may not now hurt when it comes out or hurt and they, or they just get on with it and it's really been coming out since the age of 11. They can't remember why and, and those kind of things. So the important things are obviously the age of the patient and sometimes the family history because sometimes, you know, mom and dad are there and grandparents and that they've all had telephone on stability and that changes the pathology. Thanks. Hey, g so the pathology itself, you can broadly break it down into hyper mobility. Those are obviously people who um hyper lax and therefore far more likely to come out of joint and then I break it down into rotational abnormalities. So those are the things that we're going to be driving it out because of elsewhere in the limb, isolated medial patella, femoral ligament, rupture, um patella all to either needs to kneecaps too high or a bump instead of a groove, which is basically chocolate dysplasia. Thanks sigi. So the stability of the patella femoral joint, unlike the ACL depends upon both bony and also soft tissue anatomy. And again, unlike the ACL is driven from all over the place. Um And obviously, the stability itself there is throughout the range of movement. Thanks, sweetie. So, when you're looking at that, we, when, when someone ask you about the mechanics of the patella femoral joint, three things you're going to be interested enough talking about bony, bony and soft tissue. So, what's the bony restraints? What are the soft tissue restraints? And how do those change throughout the range of motion? Okay. So, um the soft tissue restraints, which is classically a kneecap comes out in the 1st 30 degrees of flexion, you know, you're planting your foot's on hips, you of those things. That's how the kneecap pots out. It's really uncommon for a kneecap to come out in flexion. I've seen it a few times. Um It's normally because something Ziagen ical, there's something very weird and wacky going on. But by and large patella that the kneecap comes out in the 1st 30 degrees. And the most important thing is obviously the soft tissue. Now, we can talk about that in a minute. But the, the in terms of bony anatomy, obviously that the top picture is a total knee replacement that's in the process going on. But you can see that we've marked the trochlear in the right in the middle, that's got a beautiful groove, You're looking straight down. You can imagine that that's going to be forming a nice amount of congruence, see with the patellar. And um uh there's a deep groove for it to go into the sulcus is obviously the deepest part of the trochlea. Um The and and, and the most important aspect as far as patellar instability is concerned is of course the lateral lip which promised which which most prominent and stops the patella from coming out after about 30 degrees of flexion. Obviously, it has to have a, has to have a friend that has to have the reciprocal. And people talk about the bony anatomy, the patella and they talk about their either seven facets which are difficult to remember. So don't worry about that in the exam or basically the three facet, which are basically the, the lateral facet, the medial facet and the odd facet. Um and they're marked on there and they got that central ridge in the middle and the most important the patella. I mean, obviously apart from being the most important sesamoid bone in the body, um it has got a thick, highline cartilage. So it is the thickest cartilage in the, in the, in the human body which when you think about forces going through it, you're not surprised why. So the boat that, as I said, it's the, it's the bony morphology and also soft tissue anatomy that really control it. Now people talk about cue angles and if you read enough textbooks, they'll all talk about the Q angle. If you actually go to the patella femoral meetings, they don't talk about Q angle at all. And the reason being is because I think it's just, it's probably it's an anatomical thing. You've got to know what it is, you know, which is the angle from the anterior superior iliac spine down to the middle of the patella. And then obviously the net and the, and the, and the second bit of the angle obviously going through down to the tibial tubercle. But in terms of, are we actually interested in trying to measure it and alter it in terms of patella femoral surgery? Not at all. I mean, it gives you a lateralizing force. So therefore, if you've got an unbalanced neither, yes, sure, it'll, it'll drive it out, but we don't try and change the Q angle. We don't do things like that. Um You know, you may well change rotational profiles, you may well change the valgus and those kind of things, but actually Q angle itself, you don't try and change. Um in terms of soft tissue anatomy, the single most important restraint for um the patella uh to prevent lateral dislocation is the NPFL, which is the medial patella femoral ligament, which can obviously, they're just sitting between but just sitting underneath the VMO. Um I don't know if you can see my, my screen when I wriggle that but you can see whether VMO is and the but, but then there are actually a whole bunch of other um uh anatomical structures which also um support the patella on the media side, the media patellar, uh tibial ligament is the other one that we talked about and obviously the dynamic restraints. So things like the VMO, which people talk about VMO, strengthening exercise and trying to build that up to try and keep it um uh enjoined on the lateral side. You don't have a lateral patella femoral ligament because there's nothing that attaches the lateral aspect of the femur. So don't be fooled into that. It's a deep transverse ligament which attaches down from the lateral aspect of the patella down towards the I T band. Um And obviously the lateral retinaculum, the only time I've ever seen medial dislocate ear's um they come through rarely is because somebody has done a lateral release on the patella on the soft tissues on the lateral side of the patella, you know, treating pain or either instability and therefore the patient's now started dislocating media immediately. So you're going to get one thing away from this meeting, which is uh on the lecture, which is essentially don't never do a lateral release. You do it in conjunction with things like total knee replacements. If you, you know, if you really are struggling to track tracking, but if those things going on and you never struggled with the tracking. In the first, uh in the first instance, you've got to query whether you put the femoral component mall rotated, whether you've to internally rotated it and therefore trying to balance the soft tissues are not going to go well. So the bottom line is, don't do a lateral release, okay. So don't divide the deep transverse ligament or the lateral retinaculum. If you've got to do, it's part of this complex patellofemoral surgery or for other, you know, my new shy reasons, fine but, but not as a routine practice for anti you any pain. So soft tissue restraints, we talked about Iggy seen these in real life um as, as Kem more recently. Um but the so the media patella femoral ligament, as I said, it's the most important thing because it's only thing that actually controls the media restraint in the 1st 30 degrees. After that, the trochlea takes over and it's, of course, it's the dynamics. Well, it's a static restraint but tied up with the dynamics, which is obviously, of course, the VMO just above it and it basically goes from the middle, middle of the patella. So if you feel your own patella, feel the most medial bony bit, that's where the NPFL starts and come up about a third and that's where it goes to. So it's probably about a centimeter um centimeter long. And if you uh in terms of um from, from the, from the equator going further north, if you, and it's just a compensation, if you're doing any kind of patella femoral surgery, I showed you this the other day when you're cutting down on it, you often see that little bit of bone that's been pulled off on the x rays. That's, that's, that's obviously where the NPFL has been avulsed or whether they're a little bit of blood has ossified. Um And you find that and it's exactly, that's exactly the most medial bony bit of the patella. And that's where your NPFL origin and it comes down to the medial side, it runs in the second layer of the knee and it basically attaches. Um just again, if you feel the, the medial aspect of your own knee, you can feel the medial epicondyle and then there's a little dip between your adopted that and the adopted two pickle. And basically, it attaches just there in the little dip, dip and it guides the 1st 30 degrees after that, it goes slack because the bone because the bony anatomy takes over. So you don't worry about that. So it's just that guiding for the 1st 30 degrees. Thanks Nicky. So I said market muscle Axion, obviously. Um if you've got an intact VMO, it's pulling approximately immediately. And posteriorly, the muscle orientation activation, obviously change with training when you've got, if you, if you watch people with patellofemoral syndrome and you get them to do a straight leg raising the first bit of the examination. Often you see their quads are relatively poor. The VMO is not activating very well. And you see, you can see the subtleties arm al tracking as they try and fire their need. Uh they're trying to fire their quads because essentially the VMO is not acting on that dynamic restraint. Um As I said, the, either the NPFL or some of the origins of the VMO can, can disrupt through the through that first traumatic dislocation, which obviously makes repeat dislocations more, more uh likely. Thanks Aggie. Um So what is the function of the patella? Well, before we go on to sort of the, the abnormal anatomy, its function. So you can take it out as you know, but the patella biomechanics, its function is to increase quad research power during the extension. That's the reason why it's got such massive um uh That's the reason why it's got such such massive articular cartilage. It basically causes that anterior displacement of the lineup pool increases the moment arm and it takes all those four muscles which are coming from a very divergent area and it centralizes it um uh right or right on the patellar itself. Thanks A G. So um obviously, like, like, like most aspects, it's an absolutely amazing device. Um It is frictionless pulley system. This, this is where it talks about telephone will um contact pressure. So the only reason I put it in here is because the, if you think about the contact pressure's going through the patella, femoral joint, it's about seven times your body weight when you go up and down stairs. So the best way of telling someone who's, who's, you know, experiencing anterior knee pain, who's clearly not motivated to lose weight or whatever is to talk about. You know, if you put on a stone, then essentially putting on seven stone, actually equipment about the weight of my daughter or if you or if you are or if you are, you know, obviously going to lose weight, then then you gain that back again. But the result in perpendicular vectored between the quads pull in that direction. And actually the, and actually the pull on the patella ligament is of course, driving that patella backwards and that gives you the patella femoral reaction forces just like seven times your body weight. Those are the, those are the biomechanics, as you can see by flexing that new, you're driving that as hard as possible, which is when you're doing a one legged squatter, when you're going up and downstairs keep the knee bent for periods of time, going to the movies, driving, you know, driving period of time. That's the reason why you get anterior knee pain because it's that, it's that flexion of, it's that, that, that bend that creates the pain. So what do we actually do in clinical practice? Well, when, when, when, when I examined them and that my registrars will have seen this, but basically I tend to put like the patient flat on the bed, standard knee examination. The first thing I tend to do before I lay on their hands, obviously to the neurovascular examination just quickly because otherwise I forget it. Next thing I do is um I'll check their, I'll look, obviously look for their um uh you know what's they're normal rotational profile in terms of uh in terms of hip, hip, hip and also tibial torsion or femoral neck anti version of retro version. I'll look for any elements of valgus. I'll get them to do the bait and school on that side. Uh At that time before I really like any, any hands on the knee itself. Um A testing the patella, femoral joint itself. I checked the medial lateral glide, which is basically I just put to do them simultaneously to put, to put two fingers on the patella and just move it both media lateral to balance it. If you've ruptured, you're NPFL, the patellar keeps on going. And actually the people who are really who've been, you know, really dislocated these times, a number of times, then, then you can almost get into the edge and some of them will actually dislocate often without pain. Um, so they might have apprehension. There's no true grading scale for apprehension, but basically, it seems to go from people who aren't bothered to people who are literally climbed the bed and want to hit you to try and get out of there. And if it's a new patella dislocation, you, you're going to have a large effusion, you've got to look for associated injuries. These are things like osteochondral defects, um or um or things like the great mimic, which is the ACL rupture. So I must admit these days we didn't used to, but these days I image everybody within MRI scan, acute knee injury, MRI scan. It takes the thinking out of it, but it also means that I don't miss that inadvertent ACL. And I certainly have people who come in with NPFL ruptures and MCL and NPFL rupture and ACL ruptures all in one go because you, because essentially you rotate the whole of the complex through the soft tissue aspects, imaging yourself. It's rare to get a true lateral radiograph in fracture clinic because they normally come from A and E where they've done their best. But the true, the perfect lateral radiograph as you know, lines up those posterior femoral conduct absolutely perfectly. So, so that's the one that you're aiming for in theater, if you're doing any, any kind of surgery. And that, that means that you can get a true element. You get a true idea of patella height, uh patellar shape and whether you've got trochlea dysplasia or not, we'll touch on that in a minute. Thanks Gigi. So, so as I said, you know, when, when we look at it in more detail, this is what I'm looking for. So, the favorite of the examiners is to ask for different um different ways of measuring patella height. The most reliable is a Canton Day shop index. And that's the one I use routinely. And the reason being is because you've got really sort of uh it, well, when you look at into an intro preserver reliability is it's got the best, it's got the best results. And so you're measuring the articular length, which is why on the right hand diagram uh and you can, and you, you're dividing that um sorry, and you, you're taking X and dividing it by Y on that side. So a normal, a normal is somewhere in the region of about 0.8 to 1.2, something like that or one to porn 10.2 depending on what you're reading. Likewise, in cell salve RT is just more difficult to measure because you're never quite sure where that patellar ligament attaches to and also the patella length changes. So if you've got someone who's had lots of anterior new problems as a child, then they'll obviously have a very low elongated patella and obviously, you might have short patellar articular surfaces. So the insult salve rt is not nearly as useful. Um uh And then on these people always talk about Blackburn peels as well. Um Do you mind just popping the previous X ray back up? I'm just going to say the other thing I look for when you look at the right hand radiograph, I've drawn a black line along the anterior femur on this perfect lateral radiograph. If you follow the anterior femoral cortex all the way along, you can basically see there's a bump which is above it directly above it. That's that's your, that's essentially your trochlear groove theoretically, that should never appear above that black line. That sort of blue marks that line should always just join the anterior cortex. Now, varying degrees of normality are of anatomy, of course normal anywhere probably about about about five or six millimeters above if you take the absolute height from the between the black line is abnormal. Um So that that is chocolate displays on the true lateral radiograph. Okay. Don't confuse it with the lateral condos which are obviously superimposed just above it. Is that is that small amount there? Ok. Thanks Sigi. So the other thing I look at, we talked about, we talked about the insulin salvatti ratio. The problem with the insulin salvatti ratio is that you, you may well have a short trochlear or you might have abnormal articular cartilage in terms of your patella. So the patella itself might be long for your uh for your actually the amount of the articular surface. So a guy called a guy called Roland B'day published on the PTI the patella trochlear index, which is the thing I used the whole time. And that looks at the overlap of the articular surface of the trochlear on the overlap of the articular surface of the patella. And you can see here that uh if I move my cursory, can you see that? Can you see me moving the cursory G or not? No, it's not anything. It's PDF. Yeah. Okay, fine. So, so I mean, um it's a bit more difficult to explain, but basically, if you follow the articular surface of the trochlear, you can, you can see where it ends just below the patella. And then you can see the patella, the articular surface takes over after that goes further north. So you look at the overlap of those two services. And obviously, in this case, the patella trochlear index is essentially normal because there's no overlap. If you're, if you're 10% then you've got 10% of the articular surface of the patella overlapping onto the trochlear surface. So it's measures the percentage of the uh percentage of the uh patellar articular surface. And the reason it seems be important is because you're in cell cell Varty ratio may or your Blackburn or your canceled a shop index may well be normal. But actually, if you got a short trial clear, then you can still dislocated. Your patella is too high. And that's the, that's the measurement I gave. I, I used to gaze which game, which operation I'm going to do on people in order to bring their fertility to, to, to, to work out how much I'm going to bring them down to if they've got patellar alter. Thanks Vikki. So what's doing? First time dislocations? Well, first time dislocation, obviously, you just want to assess them. Have they got any of their injuries? Basically rule out the ligament injury. ACL, MCL osteochondral fracture and physio don't put them in a splint, get them out of the splint, getting the physio going. If you think they've got a collateral ligament in, put them in a, put them in a brace with, put them in a brace with collateral support, but get them a full range of movement if you haven't got any true fractures on the, on the plain radiograph and don't let them say they can't do a skyline, get a skyline because you might have knocked off a massive bit of bone that you can't see. So get a skyline on plain radiographs if you, if you don't immobilize them, if you think you got a collateral ligament injury, put them in, put them in a, some kind of Donjoy brace that allows for POSTOP knee brace, that, that's full range of movement and get into the physios and then see them after the MRI scan and request the MRI scan urgently. Okay. That's what I do. I don't do any kind of mobilization when to operate. Well, um the, the acute ones are, if you've got, obviously, you know, things like ACL injuries or you rip something off or, you know, you've got a patella ligament rupture. Those are sort of the, those, those are the ones that you're going to get in there and doing a trauma list, osteochondral injuries if they're massive bits of bone. Yeah, I'll put those back. Um There's a, there's a, uh the question that tends to come over as well. Would you do a reconstruction of the patella ligaments at the same NPFL at the same time? And the, and the literature vacillates as does the expert opinion, I think you can do simple reconstruction at the same time. Fine. If it's a complex problem, then I wouldn't. And when would you operate after multiple dislocations? I would rehabilitate them. So I never, never, I very rarely operate after one or two dislocations, they go to physio, they try and rehab, they engage property of the program and then they come back if necessary and I must discharge them all. Otherwise my clinics are more of a disaster. They are at the moment. Okay. Um So I said who to operate on? Really? Number one make a diagnosis. So don't get the, don't check the rotational profile if necessary. Get CT scans, look at the rotational profile of the lower limb to check whether the hyper mobile because those people especially good rehab. Three have they just got an isolated them and then three, picking the operation is really um have they gotten NPFL rupture? Do their property dysplasia? Have they got patella role to or do they have a combination of all of the above? And the reason why the reason why it's important is because you try and address the pathology, the disease, you're uh family who are very famous in niece for their patella, femoral surgery. Um Talk about corrective operations were not compensate ori so don't move a tubercle if you're NPFL is gone. Um You know, you want to address the pathology itself. And the other thing is that they call, talk about uh surgery ala carte, which is very French. But obviously they're saying basically address, put things back to an element of normality such that each patient gets a slightly different on different operation, which is obviously different from many other things that we do. Okay. So obviously, this lady's got rotational abnormalities so that, you know, you want to be imaging that and then you, I send that off to people like Fouzi and Damien who will, you know, correct they're lower limb alignment. I don't do the patella at the same time. I wait to see what happens I really happen properly after that. And then if they still need the patella femoral surgery, then I've got a clean field once we've taken out all the bits of metal. So let, let those guys play because it's often correcting someone, rotation abnormality is a really powerful tool and they're very good at it. So I just, I, I pick up whatever is left. Really? Yeah. Thanks, Nicky hyper mobility. I always check it because the outcomes are not as good in hyper mobil patient's and I started using things like synthetic ligaments to a certain degree but really fine ones. People talk about large, large, a bit bulky but, but some of the artery ones are really fine. And so, I mean, in terms of base in school, I'm sure you'll know it, but essentially scored out of nine. And it's basically, can you pull your thumb all the way back? So it's actually touch your forearm. Obviously, I can't because I'm old and stiff that one. Can you get a little finger all the way up? Does your elbow come more than because does it bend backwards more than hard? 10 degrees? Does you need bend backwards more than 10 degrees? And can you put your hands that on the floor? And that gives you a nine point scale and sometimes people are hyper mobile in the upper limbs and not in their lower limbs. But the important thing is that you're going to be warning people that they will get a worse outcome and more likely to redistrict Kate if they have um uh soft tissue hyper mobility because obviously using the soft tissue restraints with this lady. Um You can see here, this is a classic sort of teenage slash slash, you know, late at a late adolescent girl. Um And you can see here you've got to stand on one leg if you want to check whether they often present with anti your knee pain as well, but she hasn't rehabilitated at all. You got to stand on one leg, you do a slight squat, you can see that internal rotation of the femur. You can see the pelvis day been down, you see the shoulders compensated going the other way they need to work on really, um they need to work on their gluteal control to call that upper thigh bone as hard as possible. So they can actually get a decent straight leg raise. So, so the decent one leg squat out of it. And that's a really powerful tool if you want to work out whether people are actually um whether they're going to be um ready for surgery, get them to do one leg squad squat one, it can precipitate anterior new pain. So you look as though, you know what you're talking about and two, you can show people they haven't, they, they have really haven't engaged in the program, okay. Um As I said, surgical options, one normal anatomy. That's basically you haven't got patellar alter and you don't have chocolate dysplasia. Uh, and there's no rotational profile abnormality just doing NPFL reconstruction. We talked about where that is. We talked about where it is on the fema that points called shuttles, shuttles point. That's Philippe Shuttler who's some guy from, um, Munich, he's quite, he's quite um eccentric. Um, he's probably bit older than I am and he named this point after himself. So there we are. But you basically, you want, you want to go, it's in the saddle between the medial epicondyle and the adductor tubercle as we talked about. Okay, thanks Iggy. Um That's it there. So that shuttles point there. Um As you can see there, you basically draw a line on the, so basically up from bottom blooms, that's line, there's a little groove there drawing along the post, your aspects to fema artifacts, make a bit of kit, which is very expensive or you can just get a train play radiograph and just know where it is. And, but they put a beef pin on it. When you put it in, you drive the beef pin through the knee, make sure when you're driving the beef pin through the knee, you're not going to take out the common peroneal nerve. It's not a great moment in any operation when you do that. So make sure you're heading anterior and superior. Um When you're driving the beef pin through and then you can drill a pit and that's where your doc, your NPFL as you can see on the left hand side, it doesn't really matter what you do on the patella, but that's your docking site around the, around it on the medial aspect of the femoral calm down chocolate displays that we talked about. So you got a bump instead of a groove and it's a bit like talking about a speed bump basically hits that. The, the other, the other analogy I use patient's, as I say, it's like trying to balance an orange on a golf ball, uh or vice versa that, you know, you've got sent you to road round services, they're trying to balance and they, then they come off. Um uh basically, as I said, everything is a continuum. So you've either got people with no displays and they got massive grooves or you've got people huge amounts of dysplasia. Um, anything above about six millimeters is what the French say and we will do something similar is a potent driver for dislocation because it basically hits that bird bump there. He says she hits that bump there and gets driven out and then you see that lateral ization, then it's out of its groove at about 30 degrees. Soft tissue procedures don't work, okay. Address the pathology, do the chocolate plasty and they do work and we'll show you that in a minute here we are. So the Iggy knows these pictures because I bought him with them the other day. Um, I've got these models, I think it is in my office at the moment by loosening you sitting in my chair? Oh, no, no, no. It's like someone else. Is there someone else's? You're sticking to Smithies chair. Anyway. So this is chocolate dysplasia. So basically you can see withdrawn that anterior line down the front of the femur preoctive it, you can see the, you can see the M R there and you can see everything up north of that line, is that chocolate dysplasia. And then this is an M R cartilage model that we had done three D probably about five years ago when we were going through that phase, which shows that anti A fema should run straight into chocolate agreement. It doesn't, it's got a massive lump and that's the lump that you're gonna take down during, during surgery. And you've seen these models because they live in my desk, which is just behind his right buttock. Um, the pathology itself, when you're looking face on of the knee itself, you can see here that doesn't look like that total knee replacement model that you're looking at earlier that you've got, basically that that group is being pushed immediately. You've got a huge bump of bone, otherwise known as the boss and you've got, you've got the lateral femoral conduct, of course, keeps going up and it drops down off this cliff into that hyperplastic medial femoral conduct and it looks really odd and you can imagine that hits that, like speed bump, gets driven outside. And that's what you see on the true lateral radiograph. I get the MRI because it helps my planning and, um, that's where you got to take down, basically. Thanks Iggy. So, as we talked about the d yours earlier, um, they classified, first of all, I think it's Henry, uh, your classified A B and C and then his son gave it the D afterwards. But basically, if you've got, it doesn't really matter, you know, I wouldn't go to town on loan classification because it's not strictly, it's not massively helpful to be perfectly honest, concentrate on other stuff. But, but basically if it's more than about six millimeters and looks dysplastic, get an MRI scan and then that would be amenable to a chocolate plasty. They talk about being B and D being the most amenable. To be honest, I operate on sees, everybody operates on. See, I can't see a reason why they don't work. Um So basically if you read the literature, it says it and it's just something that's been talked about, talked about. It's ended up as a bit of folklore within the literature. It's not true. We operate, I don't worry about it. See, I just worry about how big it is. Okay. Thanks A G. So that's so whenever do a chocolate plasty, I do an NPFL as well because by definition if you've been dislocating your NPFL is gone. So, surgery, ala carte Allen does yours basically corrected. Chocolate Plasty. Do your NPFL doesn't matter what you use, but basically, I tend to use a bit of hamstring these days because it's right next door. I have used quads in the past, but the way you do a chocolate plasty is essentially you're going to, all you want to do is put a groove underneath the patella. And you do that by removing the bump, lateralizing the groove a little bit and deepening it and putting your NPFL in. Thanks, Sigi these uh Yep. So you can see here this, this patient that will go back, go back. This is one. So if you, if you want to see real life, chocolate plasty inaction, well, not really live your life, then go to a few Medi Iggy May. We'll send around a limp link. It's under my name and Chocolate Plasty. And that's this patient being operated on having a chocolate plasty. It takes about 20 minutes, 15 minutes and it will, it will show you all these these are just stills from this, but basically this patient is dislocating. You see that that can tell us completely out of joint is being driven down the lateral aspect. Thanks A G that is taken from there. Again, I've marked it on there. That's a medialized groove and that big bump and the hyperplastic medial femoral condyle. Thanks Iggy. Um The operation doesn't go this fast, obviously. And then basically that, that, that's, that's us marking the knee and essentially, all I'm doing is putting an osteotome. The osteotone goes down towards the PCL. You take out the big lump of bone, which is the top bit. So you're running the anterior flank of the, of the femoral cortex, the anti ephemeral cortex straight into the groove itself. Yep. Next there we are, we've taken out the wedge of bone. That's where we've got to get it too. So that's how much dysplasia that was. That's how bad, that's how, that's what we've got to get it back to. Thanks A G. Then we use a bird, the offset bird and we were using a light from an arthroscope underneath which trans illuminates through the cartage. So we can work out how deep the, the chondral surfaces and basically just burning away it. So you can see it's now bird all the way down. This has now given us um mobile flat which bends up and down and you can actually bend it with your thumb if you push hard enough and then basically you push it back on to where it should be and you screw it. And these days that you buy it by absorbing screws because it's an awful lot quicker. And they're just some quick arthrex ones, they seem to, they seem to work quite well. We put two of those in and then this is there. I'm taking a bit of quads MP for an M P F L, I'm just taking the top bit of quads and then swinging it on itself that's coming off the patella. And then next to the, there we are, that's the, that's the NPFL. It's still attached to the patella on the left hand side, obviously, the free bit of the graph, they're ready to be passed through the second layer of the knee. That is the medial aspect of the knee. And that's VMO, the little bit of muscle you can see underneath the Langenbeck just there at the top of the photo. And then that's a bit dark, but basically, that's just working. You can see the trochlear groove, there has been put down that will fill with bone and they fill up about that six weeks. I mean, these kids really, really fill up fast. That's just working out where the shuttles point is. That's me driving the thing through the NPFL coming underneath in the second lab and he where I've tunneled it through and that's just going beforehand and then going afterwards. Okay. So you got rid of the bump. You're looking at things Crikey has made a complete hash of that, but actually, um is that the articular surface is the thing that matters? And so I follow them up at one year with MRI scans. Yeah. Thanks, Sigi. I think there's this next one's an MRI and there we are. So you can see there's still a couple of cysts underneath the, uh where, where you got partial healing but the flaps entire stable. Um, and they get back to, we, we, we published in the American Journal Sports Met our outcomes at five years of the tropical parties and they get back to good recreational sports. We get kids going back, one of, one of them came back last week's clinic. She just some, some national bask basketball championship. So they get back to it and you can see there we've taken down that bump in this patient. The one on the left hand side is the pre up with a big bump. And now we've readdressed that groove and giving them hopefully a bit of a normal, more normal anatomy. As I said, these are the chondral map. So I do MRI scans. I went through a series of MRI scans checking that I wasn't completely raw during the articular surface that about a year. And you can see the chondral map on the left hand side is beforehand, the chondral map on the right hand side. And essentially it hasn't changed. Red is bad. That's where the contacts where the contour surface is either just getting thinner or whatever and essentially we haven't messed it up. Um patellar alter. Yes, it is real. As we talked to high concentration index or patella trochlea index. I talked about CD greater than 1.2 or a PCI of less than 12% basically. And what do I do? I bring them down and I put an NPFL in, everybody gets an NPFL. So distal ization NPFL. Okay. Next. And you can see here that one's too high. Basically, if you, I mean, you can see that on the CD ratio, you don't need to draw it on that cap is basically up in their groin. Um You look at the length of patellar ligament, look at the length of the articular surface of the patella and you realize that's about a 1.51 point something like that. Okay. Even though it looks normal there you are. That's the P T I, it's probably about zero is certainly less than 12%. You see that overlap of the articular surface is less than that on the trochlear articular surface and the ligament just looks really long and sometimes when you actually see the bag iness of the ligament when they're in the MRI scan of the patrol of the patella ligament. Yep, thanks again. And then basically you just do a tubercle osteotomy. So you make a cut down the front, cut the tubercle and make it seven centimeters long because it heals nicely. Put in three screws and then put in two of those little arthrex darts which just um they just hold the, I mean, they're Cynthia. So there's Cynthia's do two anchors, sorry. Um And that they just, they just bunch the ligaments a little bit because otherwise, if the ligament floats away, so you bring down the tube, it'll a little bit three screws front to back. And then you, you just put those two little dots in which just hold the ligament back into its normal where it should come down to normal because that's where the normal attachment to the ligament is. And then the NPFL, you can see them, the lateral radiograph and, and then I get them going. I just weightbear them uh partially weight bearing six weeks and they heal up over that time and they can start, you know, really hardcore rehab. So this is a surgical algorithm. Go home. This is all you need to know. Basically, if you fell asleep in the front of it, I'm not surprised. But this is it basically normal anatomy, doing NPFL reconstruction, rotational abnormalities, correct your rotation, then worry about it. After that patellar alta distal eyes on a tubercle and doing NPFL chocolate dysplasia, do a chocolate place in NPFL. And then people talk about lateral ization, the tubercle. It's really gone out of fashion to be perfectly honest. Um You can do it in rare if you're doing, if you're doing a bit of distill ization anyway, but don't do a true medialization of the, of the typical, it's like trying to drive from the back seat just doing NPFL. If that's all you need, it's much easier, they rehab better and it doesn't make any difference. And that's it. This, I put this in for you. These are just some extra slides. If you want to go through this, these are free body diagrams. These are some extra slides. Um But I know I knew you were gonna be running a bit short of time, but feel free to have a look, look through them. They're just some, this is a free body diagram stuff but trying to do, trying to um describe that over a zoom call. It's virtually impossible. So I've written so we basically copied it out. And then if you go through a few more, you'll see the free body diagrams themselves, which you've all seen. This is the kind of stuff that you might have to draw if things are, you know, if you're, if you're unlucky in the exam because they're miserable and this is as we talked about the biomechanics and things like that, but go through that in your own time if you fancy it. Um And it's just again, it's just a resource for you to use more than anything else. Okay. Thank you very much. I'm just going to get through them towards the end or these are, and those are just some images that were left over. Okay. Great. Fine. Are there any questions? I know we sort of race through it and it's always difficult when you can't, you know, when you can't actually demonstrate on a patient, anything else like that? But fire ahead. Uh If I just said uh question that um with your tibial tuberosity, distal ization. Um I saw, well, not recently but there was a thing about some people getting fracture propagation from there, um, from where they're making that osteotomy. Is there a way of sort of reducing the risk of that happening or? Yes. So, I mean, it hasn't, it hasn't happened yet to me. I mean, it's one of those things where you say that and the next week it goes wrong. Um So the, so I don't make any, I don't make any acute cuts. So basically, um uh the reason I go along with the osteotomy is one I can get three screws in it and to the best bit of bone you're going to get is the cancellous bone. The best bit of cancellous bone is right underneath the tube ical. So what I tend to basically do, I'm just gonna give me a second. We're gonna go old school. This is, this is I've got a bill here from the, from our latest work on our house. But basically I'm going to draw your picture and put it up and then talk you through it. Okay. So what essentially you're doing your tube ICAL obviously comes down here like this. This may or may not work. Does that work? Well, Lamberton, hold that. There we are, they charge 60 quid. Namenda Brick. So there we are. So basically, that's your patella there. That's your distal that's your distal femoral condyle. This here is your joint, this is lateral up hit here here. If you look, your patella ligament comes in just here. And that's where you put your knife. When you do your knee replacement, just release that fat pad. Yeah, then basically cut down about a centimeter in a really shallow oblique manner and then I shallow it all the way out for about seven centimeters all the way down here. So it meets the anti ephemeral cortex. So there aren't any, there aren't any acute angles whatsoever. Okay? And so you haven't. So, so one you shouldn't be fracturing this bit here because by definition, all you've taken is a shim but go deep enough that you end up with cancellous bone. I've seen other disasters where people have gone to shallow here. They end up with a tiny sliver of cortex, they screw it back on and then lo and behold, six weeks later it pulls off and it's a complete and utter disaster, try and fix it. So go to be brave. Okay. Use it. Use use of soreness osteotome to cut down here. Give yourself a good centimeter. See. Right. And can tell us bone and then shallow it out down here. Okay. And then screw it that way. And you, and you won't end up with a fracture going that way because this is so shallow, okay, because it really is shallow by the time you've done it and this is shallow here. You might end up with fracture, propagation through the screws. But that same with any screw you're putting in anyway. So the participation should be consented for that. And when I'm putting in the screws, I put them in a slightly different angle. So they don't operate like a perforation of a stamp. You can imagine, you put three screws in a quick succession front to back like that, you can check all three are going to go like, like you're ripping a stamp. So I tend to offset them a little bit and put them slight angles again. So, so you're far less likely that each fractures going to propagate because you're, it's a theoretical thing. But it just makes me feel better. Does that answer your question? Yes. Thank you very much. That makes sense. And uh skeletally immature patient's um is there any difference? Right? Yes. To try and rehab them. So if you, they tend to fall into one of two categories are three categories. It's a bit like Spanish inquisition. You guys to remember too young to remember that, but it's Monty Python. But basically, um the, if you do one of three categories, one of which traumatic, they've been walloped, fine, rehab, rehab, rehab, rehab, rehab, try to avoid anything to, they've got really bad trochlea dysplasia. In which case you've got to let them reach skeletal maturity. We've got a series which somebody's writing up. I don't know who's got it now. Um Each registrar I've given it to so sequentially failed. So if anybody wants to take it off, whoever it's got at the moment, then off you go. But basically, we're Simond Daniel. My predecessor used to operate on skeleton with immature Children, obviously Children and do chocolate glasses on them. And then we followed them up in the long term. They all did well clinically, but they're fema, either goes like that or goes like that. And that's because you either create an overgrowth of the anti ephemeral quarter, uh the anti a thermal growth line or, or obviously stalls and you carry on growing the back. Interesting. They didn't seem, they seem to be a symptomatic. So I don't do that despite Cyma telling me it's going to be absolutely fine. The, what I tend to do is I try to rehab them. If they really can't do it, then I'll do, um, I'll do an NPFL reconstruction on them. But your problem is your docking site is exactly where your distal femoral growth growth plate is. So what I do, I'm going to go old school now. Okay. So the kids' pictures in the background. There you go. So basically what I do is I make a cut here, obviously a cut here and a cut here. Okay. On your knee, you're a doctor tendons running here. Okay. So I make a pretty big hole here because as Ziggy knows when we're fixing that theme of the other day A G, we're not a million miles away from that enormous vessel, were we? And so basically make a big enough cut that you're not going to hit the artery. You can then find you're a doctor tendon running here. You have coming into the tube ical you have, you're a duct, a tendon and very bravely, you run your stryper up it for about 10 centimeters and then you, then obviously you then just click your stryper and you get half an a duct attendant coming this way. You, that's obviously right next to where the NPFL the native NPFL is. But you haven't roger any growth plates, you then run that underneath the soft tissues here and you can either you can stitch it onto the medial aspect of your patella because because the, because you're um um uh you know, your soft tissues and your bone on the anterior aspect of the patella are, your periosteum is so thick that actually can get a really good stitch through it. And that, you know, I always say to them, it's not gonna be great and it will fail in about two years. But the idea is you get them from the age of about 11 to 13. And then by the time you've had a waiting list and a bit of growth and then your new X ray and all rest of some things they've hit skeletal maturity and then you can do a proper operation on them. So it makes sense. So, a doctor too, so you're docking sites of the problems because you'll end up doddering them. So just, just use, I, I tend to use an adductor tendon NPFL if I have to do anything. But it is a bit scary, Mary. Thank you very much. It looks like, um, there's no further questions. Oh, so proceed what it uh, just very, one, very quick question for you just in general when we're seeing patient's in fracture clinic with what we suspect soft tissue with knee injuries. So you're saying, just don't quicker pad them at all, don't immobilize them. I can't think of a single reason why they should be immobilized, can you? No, I think it's sort of just the idea of just resting. No, no, no, because they want to go to sleep and then they get lost in the system. Then the MRI scan take six weeks and the physio, then they lose the physio form, then it zoom physio, then you see them back in three months. The quads are actually shot to bits and there's nothing wrong with the knee in the first place because you look like a complete chump. So, so basically what I tend to do, you know, if I'm worried about collateral ligament injury or I think they've really roger it crutches, partial weight bearing, um You know, really work on the straight leg raises physio as quickly as possible. MRI scan and if you're worried about collateral ligament injury, then get them, get them a brace, knee with, you know, full range of movement, movement.