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Good evening, everyone. Uh Welcome to this uh mastering orthopedic implant uh webinar series um delivered to you by the Orthopedic Academy. And for us are now the convenor of this uh program. Uh Today's session is a redo. Uh We have uh the pleasure again of having Mo Mister Mohammed as soI with us to redo the hip replacement um implant session for art. So is um a post CT fellow in uh hip uh primary and revision hip replacement. He works at the Center of Excellence uh world-renowned place uh right in the hospital where the origin of modern hip replacements uh came from. So he's the per perfect person to be talking to us uh this evening about um hip replacement implants. So the session will include a short term, will include a lecture quite comprehensive, but we must have a disclaimer. There's no way uh Mr Asota can cover everything about hip replacement in, in a short lecture. Uh So we focus on some of the history, some of the biomechanical concepts. But if there are any questions at all, anything else you'd like us to add uh in the future or cover in the future if you have any questions, please don't hesitate to ask. At the end of the lecture, there will be a set of MC Qs. Uh So please to make sure you're all still awake with us. So without further ado, I will leave you Mister Asilan, right? Um Good evening, all. Uh Thanks for asking a great introduction. Um Yeah, I working writing today at the moment which is, you know, a pleasure. Um And it's a pleasure for me to come and talk to you today. Um, as bra said, as a recap, um about three weeks ago. So hopefully it'll cover as much as I can uh make it relevant as well. And uh as far as said, any questions or try and answer them at the end uh with a few M CQ questions as well to, to, to get going, right. Ok. So starting off. Um, so just a quick sort of list of objectives. So, um always think about what, you know, what we're trying to achieve with the total hip replacement. Um try to cover some of the sort of history of, of total hip replacement implants. Uh Give you a flavor of the developments, er, that happened in the past. Uh What implants are available at the moment again, get a flavor of the spectrum of implants available to any hip and knee, uh hip surgeon, sorry, not a knee surgeon. Uh How implants monitored um, as well and any sort of recent advances and future direction. Um So, I mean, the kind of cases the hip surgeon may be faced with when it comes to hip pathology. As you can see here is very spectrum. So on, on the left here, you've got your sort of standard, I guess, uh, hip osteoarthritis with this left, uh, hip joint. Uh, somebody may have had a hip fracture, uh, nailed and then developed avascular necrosis. You can see some collapse of the femoral head and develop osteoarthritis as a result. Uh, you have someone here, um, who's got, uh, more advanced osteoarthritis, um, where the femoral head has eroded even further, uh, into that tab. Um, and a lot of patients who, uh, have managed over the COVID period, unfortunately, uh, could progress and, and develop significant arthritis over time, um, because it can be managed with, with a, with an operation and so worsened over time. And then you've got patients like this, this one down here, which is, you know, a young, young individual, um, who's, uh, had, you know, dysplastic hips with, with arthritis or, you know, diagnosis of like SUFI or Perthes or some sort of, um, childhood condition of the hip that's then developed into early os osteoarthritis as a, uh, as a young adult. So, that's the sort of spectrum, um, with the hip replacement. What are you trying to achieve? So, um, it is a replacement. Um, at the end of the day, uh, you're trying to manage the patient's symptoms. You're trying to give him pain relief is the number one aim. Um You are needing to achieve, we try to recreate the anatomy as much as possible. And the important things to look at when you assess um a radiograph is what you start off with. Typically. Um when you come to a total hip replacement, you want to be looking at certain things that you want to recreate. Um So patient center rotations of the femoral head. Um There are certain markers that we refer to, such as the uh femoral offset, which is a distance from the center of rotation to the axis of the femoral uh canal. And there's also the ast table, which is sort of line from the B line to the er tear drop and that's the AST table set. So overall, it's called the global off. So you, you're trying to recreate the patient's anatomy from that sense because then it recreates the biomechanics cos as well as bones, you've got muscles that are attached and these are important, particularly the abductor lever on, for example, you've got your uh abductors that, that insert. Um and you want to ensure that they remain the same sort of tension to function properly um about around the hip joint. And so you want to ensure that your offset um when you come to put a hip replacement in, it's around the same position. So these, yeah, they're not too short you've not jacked the hip out too far, which can cause pain, such trich enteric pain, um, and irritation, uh, laterally. Uh, and also when it comes to sort of, uh, leg length as well, you wanna make sure that you, uh, match or put them where they're supposed to be. Um, so that's, that's quite key to look out for all those kind of, uh, things. Now, the, the important thing when you come to look at a radiograph, in particular, um when you first sort of assess patients with osteoarthritis, uh is to look at what the femoral angle is doing. Um So normal angle is between sort of 100 and 20 100 and 35 less than that sort of a virus. Coxa vera and Coxa valgus is anything above 100 and 35 degrees. Now, um, you gotta be mindful when you look at the radiographs and assessing offset that you are um looking in a correct manner because what you got to imagine is the position of the f the femur, the rotation will change the, you know, the offset that you, that you can measure. So to get a, a proper offset, you need to really have the legs and toe rotated by about 15 degrees. And the idea of that is you are um ensuring that the X ray beam is perpendicular to the femoral neck, cos a natural anteversion of an adult is around 15 degrees, uh which, and that means that as you can see here, um as you can see here down here, um 15 degree angulation of the feme anteriorly. So by internally rotating the limb, you're bringing that down to um to. So, so the X ray beam is perpendicular and you're getting a better representation of the patient's natural uh offset. So always ensure that. So, so for this one, for example, you can see more of the lesser Trant. So actually, you should just be able to see the lesser trach cancer in a patient with adequate inter rotation of about 15 degrees. So that's something to look out for when you, when you do assess a patient. So things sort of started er in the late 19th century um and they started with uh interpositional arthroplasty with use of sur you know, different surface materials. So people, you know, um covered um the the surface of of, of the, of the femur um diff such as like rubber and things like that, but it obviously didn't work very well. And it's not until sort of actually the German surgeon clock in the um around that time that first introduced the concept of a total hip replacement um and used uh ivory stem in a cup. Um It was after that, it was largely sort of forgotten about the, the, you know, the concept of a total hip replacement. And it was in the sort of 19 twenties and thirties that the American surgeon Smith Peterson, um, sort of experimented with different materials that you can see here, sort of using glass, um, and metal caps that sort of cover the femur. Um, yeah, sort of almost a bit like the sort of resurfacing if you like. Um, so they use these metal caps but obviously these weren't great, you know, you, you sort of covering the femoral head, er, eroding into the acetabulum um, glass would, you know, perspex would break. Uh It also experimented early stages of plastic material as well, although they'd obviously um also not last in fatigue. So they were sort of early stages of, of, you know, people experimenting how they can manage people with osteoarthritis. It was in the 19 sort of forties that the French surgeon Jude um um sort of experiment to use the acrylic er hemi arthroplasty. So you can see here you've got sort of like AAA P acrylic uh ball with a, with a stem. Um that would be that that would be sort of fixed in. So this would be hemi arthroplasty. So the socket part wouldn't be replaced, it would just be a femoral head and the, these were unfortunately prone to failure where the stem would, would fracture, uh you know, the actual metal um stem part of this and it was the first um uh cause of a squeaky hip. Um But patients would, would be heard to be squeaking with, with this uh ju uh ju hip that was known as it was in the 19 fifties that, er, surgeons Austin Moore and Frederick Thompson, um, introduced their, these stems here. So the one on the left is the ost more hemiarthroplasty. And the one on, on, on the right here is the Thompson's and these are both, um, just hemiarthroplasties in the sense that you only had the ball. So the patient's native socket, um, and y you know, they, they would articulate against, against that. And, and these were actually used up until recently. And I think in some places, probably there are some more might Thompson's might still be used um for the management of patients with um neck fractures. Now, these were originally designed er to gain fixation of bone by um there are some more by encouraging bone to grow through these little holes. So the O mo was designed by plugging in bone here so that you then incorporate the native uh bone and, and, and anchor down. And you also had this sort of calcar bearing so that will rest onto the, onto the calcar part of the femur. And again, the same with the thompsons. So there's a banana shaped stem, uh which was tapered and the idea was that it would get sort of lodged into the bone and then this will bear weight onto the calcar. So that was how they were sort of anchored down. Um Then you have these additions to them to make them, sort of a total hip replacement version. So you've got the Thompson's, um, this cup with a sort of spikey anchor bit that anchors into the actual, er, acetabular bone and then the Thompsons, er, the, the Austin Mor. So he got this sort of in, um, ice cream cone sort of, er, that screw into the pelvis but look, look quite, you know, quite vicious. But, um, that, you know, that was a people's attempts at surgeon's attempts at trying to, um, a achieve a total hip replacement uh concept. But unfortunately, yeah, these were fail because, um, you know, there was a lot of friction, a lot of wear. Um, you know, you had metal on metal. Um, and so, you know, you get a lot of metal debris, uh, and soft tissue reaction and, and things wouldn't last and, and uh, deteriorate quickly. So, so there's no real way up until then of securing the implants to bone. It was all kind of, you know, press fit if you like uh, these implants in, into bone. And it was, that's where sort of come to the era of, sir, Sir John Charley, uh, in writing and he was so the first to introduce, um, polymethylmethacrylate pa, which is a bone cement, um, into orthopedics. It was actually previously used by dentists and that's how he came across it. Um, and introduced him to the world of orthopedics and found that he can in 1950. Actually, use it to uh secure his stem in the, in, in the femur. Um And so that was a sort of introduction of a cemented um femoral stem at that point. So he started using it, he then realized that to get er longevity and for survivorship of a hip replacement, you need uh you need to have an environment where there was very low frictional resistance and, and wear in the surface that was moving. So the bearing surfaces. So you had to have, you know, effortless motion between the two surfaces. So that, you know, with less friction, you're less likely then to get um particulate debris where uh of the surfaces and therefore failure. So the longer these, you know, increased durability, the longer these surfaces will last, the longer your replacement will last. So he then realized that um it was important to try and reduce the amount of torque transmitted from the surface, the bearing surface onto the implant bone interface. Because if you had a lot of resistance, a lot of torque at the articular surface at the bearing surface sign, then that force would be then transmitted to the implant bone interface. And that's where you would then get movement of the entire implant. You know that, that I that um uh interface will fail. So you can see here that um concept of trying to reduce the amount of talk. And you can compare how Charlie is first generation uh stem called the flat back in 1959 the size of the Austin Moor. Um you know, he, he would, he, he started off with Austin Moor a 42 millimeter head and then he gradually reduced the head size to 2825. And then ended up at 22.225 as the sort of most ideal head size cos any smaller than that, then you risk dislocation. Uh so the risk of dislocation after that was sort of substantially go up. So he felt that was the optimum head size to give him the to reduce the amount of talk um but also not risk increasing the risk of dislocation. So, so the first flat back er was born in 1959 and you can see that um the smaller head will mean that you've got a bigger amount of uh acetable cup thickness, uh some more material. So it lasts longer because obviously it, you know, it would take longer to wear out the material and, and this would therefore reduce the amount of debris formation. Um So, so Charlie's first stem was born in 1959. So it was the first generation, then you had, the second generation was 1974. So it was quite a big gap. Um And this, this one, as you can see, um had a thicker stem, the idea of greater surface area um to give it more strength uh around the shoulder and then the actual edges were more rounded so that there was less stress transmitted to the cement mantle um to cause fatigue failure, especially with heavier patients. So sort of more smoother, thicker and thicker stem um as well to, to reduce the risk of er fatigue failure. In 1975 he then induced a third generation know of the co the cobra. Um and that was slightly different. You can see that it's got this sort of winging here over the shoulder. And the idea of that is that um it would cause well, it it would it would improve the amount of weight sharing or weight, weight bearing through the cement. So the load would distribute more because there would be increased and it reduced the risk of subsidence of the stem in the cement mantle um on loading. So, so that was the third generation and the fourth generation um was um introduction of a new stainless steel alloy. Er so the auto 90 because of its greater strength meant that um Charlie and his engineers could reduce the actual neck diameter uh to 10 millimeters. Um And that reduces the rate of impingement. So when you move the head and the socket, there is an impingement uh between the neck and the edge of the socket. So by reducing the diameter of the neck, uh the neck, you're potentially giving an increased arc of motion from 90 to 100 and eight before you get that impingement. So that was sort of gradual um development of the uh Charlie ST. So that was the Charlie stem development. And, but then he um looking at the cup side of things, so he sorted out the cement, he knew how to bind his um stem to the bone. It's not such a glue. It's more of a grouter is what the cement is. He'd kind of um sorted out or conquered the stem issue. Um Whilst everyone was um looking at using large femoral heads, he was actually reducing the femoral head. People didn't understand why he was kind of doing that, but he was, he was going from a slightly differ, you know, a completely different angle um explaining to people that actually need to reduce the amount of to. Um and, and, and, and argued from that point of view in surgeons, slowly came round to his idea of using um using his concepts. Now, looking at the cup side of things um in the late fifties, at the same time, he was developing his stem, he actually used Teflon cups because Tefl, as you can imagine, um a surface that's very sort of low, very low friction, um worked brilliantly well initially. And he, he went on to implant about 300 odd joints, but unfortunately, um it's not actually very durable. So, although he has very low friction, it's not very durable and fell very quickly with massive soft tissue and bone destruction so he had massive cohort of patients that, um, unfortunately, um, had significant failure um, of their cups and, um, and a massive problem for Charlie massive headache. So it was, uh, so at this point, it was all kind of, it was a massive setback. Um, for him, it was, you know, he kind of always gave up on the idea of, um, his idea ever working. Um, you were on holiday. And then the story is that his engineer um Frank and writing was actually visited by um uh a, a rep from a company that bought this material along uh and the high density polyethylene. So he, he bought this material. Um and with the idea of, you know, could this be potentially used anywhere? Uh no one's really used it in orthopedics. Um Frank had tested it um, in his, in his, in his lab. I noticed that it was, it was great cos it had very, very low friction, uh the ware characteristics as well. Um You know, it would, it, you know, the pendulum er, would go on and on and on, er, when he moved the, the, the, the actual ball and within the cup that he'd created. Um, it was when Charlie came back from holiday that he introduced him to this material. Um, and, and, you know, got Charlie's attention that this is a potentially a greater material that we can use in the, in the, in the socket component of his hip replacement and that was the birth of the low frictional torque arthroplasties in 1962. Um So it all kind of came together at that point um of the socket side um where he, he's got this great material, high density polyethylene, uh brilliant friction characteristics, great wear durability. He's got his small head that articulates well, um is, you know, he's got his cement that, that bonds the, the actual er implant to, to the bone. So all that sort of uh came together at that point. And over time, uh there's the uh the development of, of the, of the, of the cups. So, uh you had the um the first one on, on the left is your initial high dose uh cups that you can see. Um the one in the middle that you flanged. And the idea is that it creates more sort of cement pressurization. You can trim the um trim the flange to, to, to fit the socket. And the last one is an OG cup which sort of an S shaped cup. The idea of that, it just, it creates more um pressurization and prevents uh sort of debris going into the joint as well. So you can see here that this is a complete set of the Charley uh low fictional torque arthroplasty. So you've got that his cement, uh his cement here bonding this stem. You can see the um the cup which is the, the wire and this is the cement that's bonding the cup to the bone. And this is the sort of Mexican hat because initially when they used to do the uh the, the, the reaming um of the acetabulum, they used to use a handheld reamer and they used to find a central point and anchor that down and then to uh with a, with a, you know, handheld device, they would, they would ream out the, the socket and that would then fill that with a metal mesh and that would be cemented in some little Mexican hat. And then this is the trochanteric costotomy wiring because that's how we used to approach it through a trochanteric cost. So really, um which, which is not, not really used anymore. Um That's the approach that he used into the hip. Um And then he'd wire it back up. Um And that's what you'd see there. So, so that's all the components there of the, of the Charley Charley Hip. Now around the sort of same time, uh you had other groups and, you know, famously the Exeter group uh led by Robin Ling and his engineer Clive Lee um working on um the Exeter stem, uh which is, which actually follows a different type of um philosophy to the Charley Stem. Um As you can see, it's a, it's a double tapered design um and it's shiny. So it's not matte finish like the Charley Stem. Um And their argument was that the use of cement or cement itself, the properties because of the viscoelastic material, it's actually most, you know, greater strength under compression um rather than a, you know, under stress, tensile stress if you pull it or sharing. So the idea of a taper stem is on weight bearing, you are tapering into the actual cement mantle and you're allowed a bit of subsidence. So the extra stem is designed to um you know, su subside um a very small, you know, amount of, you know, 0.1 millimeters, but over the duration, you know, um you can't have too much subsidence, but it's designed so that every time you weight bear, you anchor further into the cement. And this is called the taper slip concept uh as opposed to the composite beam, which was the, the concept that Charley uh followed with his um with his stem. So you can see here that the Charley stem um the the the loading force. When you load the stem, the load goes down and dissipates distally. So the problem was sometimes that you get this part of the femur would not be loaded that much. Um And you get sort of stress shielding. So sometimes you get some wasting away of that bone. Um and, and the distal Anchorage uh will mean that, that, that, you know, the stem over time could fatigue cos you may get movement at the top end but fixation at the bottom end. Um And you get fatigue fail the stem. However, with the exeter, the idea of the taper slip, um such as the exeter stem is that the force has dissipated equally throughout the length of the stem. Um, rather than just the distal part as in Charlie. So two different concepts, they're coming from different angles. Um and they're both sort of, you know, present at a, at the same time. So the C stem itself, um, actually, you know, is a, is a following from the Charley Stem, er which you can no longer really get a hold of. You can see over time that that's the first generation of the Charley. And then you had this um very first C STEM design um introduced to 93 and then gradually over time, you saw this is the classic and then the latest is the A MT version. Um And actually, interestingly enough, they've kind of gone to the to the um taper slip design like the Exeter in terms of uh concept, er and left the composite beam concept. I mean, you still get other designs at the moment that do follow the composite beam. But the C stem, which is um a further development of the Charley uh has gone on to be a polished triple taper design. Um because the exeter is only a double taper, the C stem is a triple taper, the idea that it's tapered in all three planes um to provide a bit more reputational stability, uh, and there, and there are, there are other, um, designs out there as well. Now, this is what I alluded to this, to Charlie Pendulum. So he used to, uh, you know, demonstrate how good his implant is. His, er, set up was compared to, er, competitors. You know, he'd, he'd set this up and then he would get the pendulum swinging and then he'll, he'll, you know, show everyone how, um, his low frictional arthroplasty will, will, you know, last a lot longer in terms of pend will continue to er, to beat compared to the other ones which will stop very quickly. Um I've put the slide out just to sort of a background on um where, so you can see here on the graph that uh femoral head size is quite key. Um And you've got two types of wear. So you've got, got something called linear wear and volumetric wear. So linear wear is the amount of penetration through material and volumetric wear depend on the surface area. So the amount of surface area um don't know um where that happens. So with, with a larger head, obviously, you get more volumetric wear and with a smaller head, you get more lenient wear and somewhere in the middle sort of 28 to 32 millimeter heads is thought to be the most ideal in terms of um compromise between the two. So the big heads, you're thinking that really, you know, failure is due to the er the amount of osteo uh you know, osteitis from the polyethylene um that's created cos a lot of volume and the small head is more potentially through penetration through the material um that could resort to failure, uh thinning of the material as you penetrate through it. So just um a little thought about that. So just cover the evolution cementing technique. So I mentioned P ra and how Charlie introduced it in 1958. Um The actual, the way of cementing has, has, has drastically changed over time. So, you know, Charlie used to just use a bit of hand mixing and he used to pack it in um without preparing the canal or putting a femoral restrictor on, he used to just pack it in with his thumb. Um and then put, put the, the actual stem in over time. The second generation, you have the introduction of the er cement restrictor, like the harder restrictor here. You've got various different types on the market and some surgeons actually use a bone block, er, rather than any, any of these materials. You've got a cement gun as well to help you pressurize the actual cement in the canal. So you've got a restrictor, you're able to moisturize and make sure you've got the cement, you know, interdigitate into the actual bone or in, into, into the bone so that you're getting a great Anchorage. Um But before that, you want to sort of brush and dry the. So you don't get any blood mixing in at the interface. And uh delaminating third generation introduced uh vacuum mixing to reduce air bubbles and the cement. So you don't get uh problems with uh um crack propagation, cement pressurization. I spoke about using uh these sort of, you know, triangular blocks in the proximal part. You may have seen people use that and, and the induction of post vs to, you know, dry cleaning and um washing out the canal really well, the fourth generation introduction of these centralizer distally uh to, to make sure the cement, the the stem is as central as possible in the canal. So we've spoken about um cemented implants. Um but they're also uncemented implants that are present on the market and obviously prior to Charlie, they, they were uncemented. But the concept of um uncemented is you either have bone uh ingrowth or bone growth. So, um the idea is you wanna get primary stability by having bone uh either growing amongst all these little pores that you get in the, in, in the surface of the material. Um And there are certain characteristics, you know, you can't do, it has to be about 40 to 50%. And the pore sizes have to be within this sort of range to um to be to, to be um sufficient um allow the bone to row and incorporate into the surface because that way you'll get then all all actors. One and you get primary stability, you won't get any micromotion because if you do get micromotion, you then unfortunately never develop stability, you never get bone, too much motion. You'll end up with fibrous tissue and then you can get into parents train the and all that kind of stuff, which is beyond the scope scope of this to. But um bone on growth is different, um slightly different in that you have sort of, you know, peaks and valleys in the material. And the idea is that the bone oh grows onto the surface such as, you know, hydroxy appetite, um need for certain thickness. So you have no pore but you only have divots on the surface. And the idea is it grows in out and it creates a friction in that surf in that surface to prevent the motion again, achieving prime stability. By that means there are different implants that are available uh especially for revision uh surgery. So you have um you know, different types of an amount of uh coverage of, of these materials to achieve what I've just spoken about. Um But the idea is to achieve prime stability um with all these, all these implants and there are these two ways of, of, of, of achieving that. So you can see down here, there's a socket also with like an augment again, made of this porous material. And it's sort of to achieve Anchorage into asset happening as tabler components. Again, um several different types, as you can see here, you've got the same thing I just spoke about. Some of them got holes in them and you can put screws in as well. And that provides sort of secondary stability into the bone. So as well as getting the uh ingrowth or growth, uh you, you can also achieve extra stability using screws. And that's the example uh there um this is a picture of uh what we call augments. So sometimes if you've got a bit of a bony defect, you can use these um sockets, but you may be left with a bit of a defect. So you've got an option of, of using uh these little metal triangular er sizes of different s you know, it depends on the defect size. You can then anchor that into it with a screw and this is made of the same sort of porous material. Um And again, that will allow incorporation to host bone here. I've put examples of um what we call er so these are composed of bipolar um or um articulations within articulations if you like. So you can see that this is the shell that anchors into the socket. Then you've got plastic poly that can articulate within that shell and then you've got the femoral head that articulates with that one. So um these are great for and they are used for patients who have problems with stability or risk of dislocation um people who, you know, have got uh muscle deficiency or um, nerve injuries or weakness or even patients who had revision surgery. And, uh, you know, there may be increased risk of getting dislocations. And this is an option where you're, you're increasing the amount of movements. There's two sort of articulations. Um So to dislocate this, you know, it takes a significant amount of force, uh to, to do that, I've also put here um for more complex um cases, you can see that uh these are sort of tri flange, custom made implants in some patients, particularly revision, uh not so much in er primary replacements, but in revision replacements, you sometimes face with a problem of significant bone loss um where you don't really have a socket and on top of that, the type of bone around it may be very weak and this is like a heat map that um with a CT scan, um you can um identify areas of bone that are good quality and bones that are not good quality, er, where you won't achieve Anchorage. So idea here, for example, with this kind of implant is that you've got a socket and then you've got this sort of trilan sort of three anchor points that you can then um secure into whatever bone is left in that he pelvis, uh if that's in the ileum pubis initi um and then you can cement into this actual, this is almost like you're creating your socket if you're like your native acet table and then you can put your implant into that. So this is a dry flange or custom made, you know, you get act scan uh work out the defect. Um and then you can reconstruct it. So this is way far, you know, far down the construction ladder. Um But these are just flavors, I've just put out in terms of what's, what's out there for the A tablet components, thermal heads. Um So your typical metal or metal, so Cobalt, chrome metal heads, um you've also got your ceramic heads and yes, this is, the head is obviously more expensive than the Carbot chrome metal heads. Um Some surgeons use, you know, ceramic heads for younger patients um because it's got better wear characteristics, durability, um last longer, et cetera. While you know, for, for an older patient, you may argue that, you know that the hip last as long. So you could argue using something cheaper like a Cobalt chrome metal head. Um The ceramic head itself has gone through uh three generations of change. Over time. There were problems with brittleness initially fracturing. Um But over time, um the way it's made has been substantially improved, uh has made it more durable, still brittle. Of course, as a ceramic is the material. Um and the main problem really is uh fracturing uh particularly with a, with, with ala liners uh if they're not quite seated properly. Um or the, the tablet uh component is m uh malaligned, then you can create a lot of stress on a particular point. Uh And that can, that can make it prone to, to, to, to fracturing. Um The other thing I've added here, uh some of you may or may not be aware of is is the sort of scratch profile. So when you scratch a metal, you get uh this V shape, you also get these little spikes in the surface. Um and that roughens the surface as a result. So that could then increase the roughness and possible wear um of the softer material, which in most cases would be the polyps. However, the ceramic scratch, you get a smoother and not such a rough peaky um outline. So the scratched profile of the ceramic is much better than that of the metal uh head. There is something else called oxonium head um which is a metal head, but uh the surface has undergone transition to a ceramic er under sort of immense pressure and heat has become a ceramic surface. It's almost like a best of both worlds, but it is obviously very expensive. So probably not the best of both worlds in the sense that it's not as cheap as the metal head. Um but it, it, you know, it's, it's, it's an exciting option um becoming more and more common um data still young. Um But promising, as I say. So, you know, that's also an option. So you may have come across uh use of oxy heads and hip replacements, just touch a little bit of one templating and pre op planning. So, as I mentioned at the beginning of the talk, it's quite important to be able to um look at an X ray uh and understand what you're looking at when you come to operate on these patients. It's also useful to have an idea before you go in uh with a, you know, with a plan. So, you know, kind of what potential component sizes you need. Um You know, any anatomy abnormalities that you need to consider interoperatively. Um You wanna make sure that you are when you're operating on a patient and you've got the hip open and you're preparing the femur or the socket, you wanna ensure that you're templating similar to what you're seeing, you know, you're not a million miles off. You know, the size is not a million miles off. Um Templating is not 100% but it's a useful guide um for the surgeon to appreciate the patient's anatomy, the offset we spoke about the leg length discrepancy. You know, how far do you need to put your stem in? Um How far, how far do you need to sink your socket in? Um All those things need to be considered and pre op templating is a nice little sort of warm up, I guess. So, you kind of know what time to, you know what to expect when you go in. So this is an example. Um there is the, this is a king marker, there is, there's also this little ball, um There's diff different things on the market. The king marker is thought to be fairly accurate cos it sort of takes into account. Um you know, these are uh lines and, and balls and it software automatically calculates the amount of magnification uh to give you an accurate estimate. Um Here, you can see that, you know, I've drawn sort of a line from tear drop to identify where I am. I previously marked out your leg length, you need to work out if the leg's short or long on that side, position of your socket. Um and you wanna recreate the patient's natural offset. So you wanna um e ensure that the rotation, you know, the central rotation is recreated. Um And you know, little things like the, the, the depth the stem, how far you need to put it in. Uh some pa some surgeons mark out the er neck cuts, how far from the less cancer. So various little things that different surgeons might do. Um So yeah, this is a little bit on, on templating and that's obviously a two D templating. So it's not 100% you know, ultimately, you know, uh three DCT templating is even better if you really wanna get uh more technical. So, you know, how, how do we, how do we monitor, um, how implants are, are doing? And, um, for us, obviously, you may have heard about the, the N Gr the National Joint Registry, um um for hips and knees. It started in April 2003. Um So this year, sort of your 20th anniversary, uh our submissions weren't compulsory up until April 2011, believe it or not. Um But other, other countries are sort of ahead of us. You know, the Scandinavians uh really good, keep a record of uh of, of implants and, and actually, uh they're the ones that brought to light the problem with the metal on metal total her placements, the ASR. So, you know, they flagged up the fact that these were failing early. Um and, and then became a uh international news and, and that, that's the important thing about the about joint registries is that it identifies how implants are doing um of any early, of any early failures. Um Because you, you gotta know that as a surgeon when you come to concern a patient, you've gotta tell the patients how, what implants you're using, you know, why these implants, you know, why they've been chosen. And I'll come onto that in a second. But the, this is the latest from the N GR. So you can see that uh over time, um things are largely uh static. So the exeter this is the type of stems that have been used, the exit is the most commonest use. Uh By far, you've got the, the orange one here is a CPT. Uh the blue one here, you've got the C stem that I spoke about. So the CPT is another uh type of stem. Um There's a slight overlap and one's is overtaken the other. And then the rest is sort of uh very similar the uh the bearing surface. So you can see that uh this blip is just during, during COVID. But overall, the by far the commonest of the metal head with a poly uh socket. And um uh over time, um the ceramic on poly is actually uh increasing in usage. So it's now reached a stage where the ceramic on poly is more commonplace than the meth on uh poly. And um and actually ceramic on ceramic is um sort of going down. Uh And that's probably, you know, these numbers I suspect are just added to, to this number while the metal on, on, on poly probably continue to be at the same sort of um numbers that have been putting in um metal on metal down here, it's always been very, very low and continues to be. So, um but you can see here interestingly, the ceramic on poly um is going up in numbers, OK. The type of um configuration so cemented with both a socket and the stem um cemented in. Um You can see that um that sort of going down uh as compared to hybrid, which is sort of uh equally going up uh in frequency. So the hybrids where the, the socket is uncemented and the stem is cemented. Um and the, the reverse hybrid, which is not on here is the opposite uh cementless. So again, numbers are fairly sort of static in where both components are on cemented and the resurfacing is is is minimal. So um ODP rating. So this is, this is looking at how that's what and what and what ODP stands for is orthopedic data evaluation panels. So this is a group of independent uh panel of experts, uh clinical nonclinical um they experienced in the orthopedic industry and decide um the rating of individual implants. And this is dependent on, you know, the numbers that, that are out there. Uh how well uh they're doing from the N GR data and you can see here um and you know, the available research uh on these implants as well. So the different ratings depends on. So if you look at the maximum revision rate for, so there's a number of years, there's data on an implant. So for, for an implant, that's 13 years, uh follow up can't have more than a uh 6.5% revision rate uh at 13 years that will be given um given, given that 13 day rating. Um So that's just a little guide. So you can kind of explain to patients, you know, whether you're putting in a, a 10 A rating, a seven a rating or a 13 A rating uh component. Um What the data is out there to support the use of this component. What's the long term, uh date to say revision rates, the failure rates, you know, all these kind of, um, little, little bits of information that are important when you come to uh choosing plans and consent patients because they will potentially ask you for why you're using this implant, not this one. And the star ratings like, you know, addition, you know, beyond compliance, basically where product, um you know, where, where it is now, this is examples of different components that got a 13 A star rating. Uh, you know, you're at your, at exeter stem, the the cup. Um You got the marathon cup here and you've got the uncemented uh pinnacle, you've got the kai uncemented stem as well. So, you know, these are sort of over depth 13 a star rating, but it's important to know that if, if, um, an implant is made of more than one component and it may be that, that actual makeup, what the rating for that makeup will be, um, will be at the, at the lowest. Uh, if one of the components is a seven A star rating, for example ODP rating, then the whole thing will have a seven A star OD E rating. Uh Even if if another component or another part had a 13 a star rating. So, so it, it, it, you know, it depends on the, the component with the lowest ode rating. So uh a little bit of flavor. So just sort of um summarizing what we've covered and what, what things are. So you can see that uh this patient's bilateral replacement. So they've got an uncemented um cup on both sides. On this side, they've used screws to augment, provide a bit of secondary stability. Um Both sides, you've got uh uncemented um calcar bearing uh components. You can see this little calcar bearing on both sides here. Um This patient, uh unfortunately, he's got a, a failing acid tablet component. You can see that there's a bit of lysis around uh the socket, the socket looks a bit more vertical as well. Um So now it's not the same patient, but um with this one, for example, on this side, um this patients had a revision operation. So they've got an excess of stem here. Um They've got a, a cup, they've also got this uh very large um metal augment and buttress and this and this is, and these are used when you have significant bone loss um and revision surgery. Uh typically, uh you then need to use those augments that I showed you earlier um to fill any defects. This patient's got a even crazier uh acid tablet. You can see that sort of dry flange um uh component that II spoke about earlier. All these screws going in multiple directions to try and get as much purchase and all the good bone that's available. Um And, and, you know, again, these are sort of reconstruction options uh and revision operations. I didn't quite cover resurfacing hip replacements, but that's one. Burning hip resurfacing is the most uh popular one. That's no longer really uh used, put very rarely in very select cases, uh very select centers. Um But that's, that's resurfacing here on this side. This is a metal on metal. So you see a large head, uh a total hip replacement. Um In this case is quite interesting because if you look carefully, you can see some extensive lysis uh in, in, in, in the pelvis there and also the proximal femur. So this patient is awaiting um major revision surgery on this side. Um A joint case with the pelvic team because you can imagine that there's a substantial risk of bone loss here when you remove this component, uh you may not be left very much. So, reconstruction options are going to be quite tough. Um But that's the problem. Metal on metal, we can get, you know, soft tissue and bone resorption. Uh And, and you're not left with very much uh to, to kind of reconstruct. So that's a metal on metal to placement. Um Some patients, so it's like AAA capture up or constrained liner. So you've got where patients are at risk of dislocating. So you've got an option of trying to reduce that risk. Um, with this, you could just suddenly see there's like a ring, er, the base of the, er, base of the socket. I didn't give that as an example earlier. Now, um, on the femoral side of things, you can see that, uh, some patients, you know, this is the original Charlie in and over time things have loosened. Um, and you know, the amount of bone stock around here once you take the stem out, um is it very dubious? Um and you know, it can easily sort of fall away and, and unfortunately, you know, patients that have not got much bone stock here to reconstruct, give you some options from a revision point of view. You know, you'd be looking at like a proximal femoral replacement like this where you, you just have unfortunately cut away uh that proximal uh part of the femur and, and throw it away and give them this um giant lump of metal. Um that's uh you know, to, to, to give him some function. This uh this patient down here again, this is a femoral revision stem. Um and you know, they would have had the whole component removed uh due to due to uh loosening and failure. Um and this is a very different type of stem that's uh it's uncemented that I spoke to you about earlier. Uh and it purchases um in, in the diaphysis er in here now, these, these are um these are cables, uh sometimes you put prophylactic cables to prevent any fracturing. Uh But I know exactly about this case, in particular where there was a, a break here that they had to cable. But this is, this is a revision sort of stem um to address uh problems on the femoral side. So in terms of advancements, so, you know, you're probably more than familiar or heard about. Um I mean, there's always been uh navigation, but now more and more in orthopedics in orthoplastic surgery, there's the introduction of robotics or the use of robotic surgery at the moment. I think it's probably more so in, in uh knee replacement, but it's, it's coming more commonplace in, in uh helping out in hip replacements more so on the aceta side. So the placement of the socket uh is the idea of the robot is it helps you uh with the CD with, with um CT planning uh to like, you know, single, single ream, single preparation of the socket in the exact position where you want it to be um the exact angle and inclination, et cetera to then place the uncemented component. Um On the femoral side, there's no real benefit from robotics point of view at the moment that might, that might change. But at the moment, that's not, that's not really it, it's uh it's used made on the, on the side. Uh A I of course, um we want to know about A I and how it's, it's been used increasingly uh in the world around us and it's gonna become more complex um in orthopedics, it's, we're already coming across it, using it, you know, reading X rays and identifying fracture lines and, and things like that. So, you know, this can become more uh more complex. Maybe the use of algorithms may even be templating, uh might automatically template something for you and tell you the most ideal position, et cetera. So, you know, I'm sure that will come in um patient specific implants and uh and 3D templating and use of CD uh uh um CT uh software to do that for you. So some patients may have awkwarder anatomy um from previous childhood deformities or previous fractures or, you know, all that kind of stuff that makes um the use of uh off the shelf stems very difficult. Um And you may therefore be uh looking at uh using custom made um implants to fit the patient's anatomy. So, you know, um stems that are um that are angled or bent to one direction, et cetera. Obviously, these are all within range, all within limits. So when these are engineered, er, they are then put through software to ensure that they don't fail prematurely, et cetera. There's no point giving a, a patient a femoral stem that's ideal for their anatomy. But then ultimately, you know, it may fail because of the design and the amount of forces it, it copes with et cetera. So it's all within, all has to be within, uh, uh, limits and it is extensively tested, uh, but here a little bit on 3D printing and, and the use of 3D printers at the moment, right, until we quite commonly, er, get 3D printed models, uh, of, uh, anatomy, that's very difficult. It just gives you a nice, um, uh, overview of the anatomy. Um, and you're able to part of your pre op planning, you can appreciate any bone loss. Um and, and you can even do dry runs. So you can even um using these, you can ream into them, you can uh cement components, see the, the um component orientation as well. So it gives you almost like a uh a mock mock set up of the real thing. So it can be very useful and um day case arthroplasty. So this is becoming um more and more of a hot topic. Uh A lot of centers are driving forward to try and um further improve the patient experience trying to get patients operated on or optimized, operated on, manage their POSTOP pain relief in an efficient manner, get their physiotherapy um done efficiently and, and you know, out the same day, if not potentially um out the uh you know, the following days. So there's, there's a greater, greater push to further improve, uh you know, the the enhanced recovery gone the days of when Charlie did an operation where patients would be in bed for two weeks. Um, you know, without moving, you know, the idea of they need to be staying in bed for everything to heal up and then they move, then we've gone to more recently the enhanced recovery where patients, you know, would be amazed, you know, they're out by day three and four now pushing that even further and we're going towards day K surgery. So, you know, for forever trying to push um push, push that boundary. So um that's the, that's the end of the um presentation. Thank you very much, Mo That's wonderful. Thanks for taking us through this uh hip replacement history, biomechanics, uh advancements. Wonderful. Again, good revision of the topic. Excellent. If you would like to go through the MC Qs, if possible, we can. Um Yeah, that would be, that would be fine. I've got three. So um oh, it's getting really bad. So um we can start with, with this one. So um what was John? What's John Charlie best known for? So um use of large femoral heads to reduce the risk of dislocations or did he introduce the taper stem design or coming up with a low frictional um torque arthroplasty concept or using uncemented femoral stems? So, what was he best known for? Ok, guys. Uh just try to put your answers. Number three. Majority going for number three. Fantastic. Yeah, good. So I've been listening. OK. Um So how, how do uncemented components achieve hold in, in, in host bones? So, um is it through the use of uh cement? Do we, do we rely on ingrowth or growth on the bone um through the actual surrounding fibrous tissue or through the use of screws? And we have here option number two going for number two. Yeah. Fantastic. So, as we covered earlier, so that's so your primary stability. So three screws and your secondary stability. And obviously you wanna avoid the formation of fibrous tissue because that's, you know, that's not gonna achieve any form of stability. Um So in addition to magnification markers, uh how should a pre op radiograph be taken to facilitate templating? So what's the ideal position? So do you center on the hips of the legs and 15 degrees of external rotation or should you have uh center, center on the hips with legs and 15 degrees of internal rotation, some slight flexion or do you center on the hips with legs and 15 degrees of internal rotation, slight abduction or do center on the hips with 15 degrees of entire rotation to account for the natural 15 degrees of femoral anteversion. So they are going for option four. Fantastic. Very good. So that's uh we'll be listening to some of that stuff as well. Yeah. Thank you. Good. Thank you very much. Uh Mo for going through this um very interesting lecture on hip replacement again. Um I was wonderful. You're welcome. No problem. Yeah, I think you got everything and uh it was a very nice, wonderful recap of this uh subject. So, thank you very much again uh Mister Sultani for joining.