Failing TSR Part 1



This teaching session covers primary shoulder replacement surgery, providing medical professionals with a general overview of the anatomy and principles behind the surgery, with a focus on the WS classification system that underlies many surgical decisions. It also covers the difference between inlay and onlay designs, as well as operation errors that can lead to shoulder replacement failure. Attendees of this session will leave with a clear understanding of the operation principles behind shoulder replacement.
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Part 1

Learning objectives

Learning Objectives: 1. Understand the normal anatomical parameters of glenoid retroversion and humeral neck shaft angle. 2. Develop criteria for initiating total shoulder replacement. 3. Learn the WS classification system for shoulder arthritic wear patterns. 4. Understand the differences between inlay and onlay reverse shoulder replacement designs. 5. Comprehend how to choose an appropriate implant for shoulder replacement and reconstructive surgeries.
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The following transcript was generated automatically from the content and has not been checked or corrected manually.

Yup. Done. Cool, thank you. Ok, cool. All right. So last week we talked about, um, stiff shoulders. Ok. So, um, we went through quite a lot on a frozen shoulder and, um, predominantly the main sort of ones that you get asked about in the exam are gonna be, uh, in short cases. As I said, the examination we went over last week. So that's basically identifying, uh, a stiff shoulder. Uh, and then essentially when it comes down to electively is working out whether it's arthritis or, or frozen shoulder. Now we covered frozen shoulder quite extensively last week. Um, I noted in some of the feedback people said I hadn't told you what you need to know for the Fr CS exam. Um, I'm pretty sure I said at the start, this is all you need to know for the Fr CS exam. I think I even gave you papers. So not quite sure, but actually, um, I'll, I'll cover what you need to know about after the last you for the Fr CS. Ok? You've got to remember it's a general exam and exam. Nobody's expecting you to be an expert. Ok? But you, if you stick to principles with a lot of these things. Uh, you'll, you'll do absolutely fine. Ok. So today we're gonna talk about hopefully not just the failing with shoulder replacement, not all shoulder replacements fail. Some do work. Um, so, but we'll go through the basics of, of, uh, primary, uh, shoulder replacement and we'll talk a little bit about where all goes wrong. Ok. All right. So if I get a smooth, ok, so we'll talk today. I want, I want people to come away from this really th with some kind of way of, of decision making for, for total shoulder replacement. Um, now most people are aware that the, the, the main types of shoulder replacement being an anatomic or reverse, that's where a lot of decision making is around. Um, we've covered a lot of stuff last week about, um, the examination and indications for those things, but we'll, we'll briefly touch on those again today. Uh We're gonna think about how shoulder replacements fail. So what, uh, w when we talk about something failing, um, anything failing in orthopedics, we need to, if you're doing an, an operation, you need to understand how it can fail, uh, in order to know how to fix it when it does fail. Ok. And we'll talk about revision and reconstructive options that are out there for, for, for shoulders. Ok. All right. So, starting off. So the normal glenoid retroversion we touched on this last week. It is is between 2 to 4 degrees. But that's what the textbook would tell you, but most people would accept anything up to 10 degrees being normal. So by that, that's, that's measuring the angle of retroversion of the glenoid itself. OK. Normal humeral neck shaft angle is 100 and 35 degrees. That's about the only two measurements you need to, to remember. OK. There are lots of other things if you look at that are lines that you can draw all sorts of things like that. But realistically, the only two numbers you need to remember are the, the glenoid retroversion and the humeral neck shaft angle. OK. Why is that important? Well, it's really to do with um, what you're trying to do in terms of arthroplasty is all based around these two numbers. OK? And as we go through this talk, you'll see that there's, they do pop up again. Um But essentially this is what we're trying to correct with any operation. So it's the same principles as a hip, hip replacement, a knee replacement. We're, we're trying to essentially correct back to this normal anatomy. So any operation we're doing in terms of arthroplasty, we're looking to get the glenoid version back to somewhere around 2 to 4 degrees. As I said, the upper limit would be 10 and hum or neck shaft. Dale really is to do with, with the way it's cut. So when you're cutting the neck, uh to put an implant in. This is what you want to try and replicate. OK. Right. So what classification, he wants to tell me about the WS classification. So this is, this is the other thing that comes up, which is basically looking at, at w classification and explaining that and what the relevance of that is. So he wants to have a crack at this. I've been very kind and I've put pictures up to help you describe it so I can have a go. So, so a category is where you start to have central wear, which goes superficial wear to deep um central wear and then progressively you start wearing the posterior wall of the glenoid. And then you have this B one and B two where goes in more and more retroversion. Yes. C is where you basically, you are completely retroverted. Yes. So, out of those ones. So essentially with that B one, as you said, it is to do basically with the amount of retroversion that you get. So the, the B one is essentially what you call a bi concave um glenoid. OK. Now, what's interesting about that is, do you think that's a pathological abnormality or is it, or is it a, an anatomical? So is it a pathological process or is it something that you, you or is it a sort of normal variant? So the more you lose the glenoid posterior, the more the head is going to sub lax posteriorly. So the more it's going to wear. So it starts with just minor subluxation posteriorly. And then the more that the glenoid is eroded, the more the head subluxed. Yeah. So that's true. Definitely. That that's the process by which you end up with that progressive wearing thing. But actually a B two A bi concave glenoid can be a normal variant. So people can be born with an anatomical variant where they have essentially A B concave. So the B twos tend to be, it can be ones that are anatomically normal. If that makes sense, that's not a necessary pathological thing. You're quite right in that the, the subsequent subluxation and retroversion you get as a consequence of the wear is, is definitely due is exactly the process you've described. You get that progressive subluxation of the hum head out posteriorly and increased posterior wear. So the thing with shoulder arthritis is that, you know, essentially there's two main patterns of wear that you need to know about. One is the central wear which Maria described, which is your a, a glenoid. OK, which is as you described, minor wear and then sort of deep central wear. OK? Your B glenoid are basically your by concave ones. So B ones are basically that there's, it is sitting subluxed because if you look at that diagram there, if you were to draw a line um along, you know, here at the central axis which is Friedman's axis, you know, along the center of the glenoid. You can see if you then drew a line across that. You'd see that at least about 50% of the head is subluxed there. OK? As you get increasing where you get this, this more by concave shape. Now, BT S by definition are ones that have got at least 70% of the humeral head subluxed or that there's 15 degrees retroversion of the glenoid. OK? And you measure glenoid retroversion. Again, if you draw a line up Friedman's axis, you do a point between the point between there and draw a line 90 degrees of Friedman's axis. It's the angle that you're getting from between that 90 degree line and the line between the glenoid. OK. Now A B three is, is massively retroverted. OK. So it's not really by concave anymore, is it, it's just it sort of worn its way up and in into the, into the glenoid. So you get more, more retroversion with those ones, as you correctly said, C C is basically any glenoid that, that has um retroversion of more than 25 degrees. OK. So that's, that's what AC is. And D I said to David earlier CD is one I've never seen, which is an an which is anterior wear, OK? Which is much less common. As I said, the most common pattern of wear with a, with AAA arthritic shoulder is that you end up with this, this um posterior wear pattern. All right, So the most common glenoid that you see when you're doing a shoulder replacement. So probably between B three and C 12. Sorry. Yeah, BB two. Yeah, I think Luke said B two. So yeah, BT is the most common common variant that you see. OK, good. All right. So this is important. Why is this important? So I haven't, I, I, I'm not one for going into classification systems for just because there's loads of classification systems, right? This is important because it, it helps you think about how you're gonna subsequently manage er a shoulder. So, so I want you to bear this in mind as we go through, uh go through the cases and things because this is essentially key to how you're then gonna reconstruct. OK. So ws classification is important because it tells you how to manage the glenoid basically. All right, good. So next, I wanted to talk about um just a couple of other differences coming back to that neck shaft angle. OK. So I've put most anatomical shoulder replacements will, will, will make you do a neck cut at about 100 and 35 degrees. OK. That makes total sense, doesn't it? Because the normal neck shaft angle is, is 100 and 35 degrees. So, therefore, anatomic shoulders, you can cut 100 and 35 degrees. All right. Now, I've put two types on the left there, there's a picture but you can see that the neck shaft angle differs between the two stems there. Ok. So there's one's 100 and 55 degrees and one's 100 and 35 degrees. And why is there a difference with? Now? They're both, they're both used implants. But why is, why is there a difference between the two, uh the, the grand? And so I think lies more inferiorly and uh more adapt towards the uh uh relative to the, to the anatomical Gle to uh increase the tension of the deltoid. And at the same time, prevent subluxation of the, of the implant. Uh Yeah. Well, I hope any reverse shoulder replacement would stop some relaxation of the implant. Um So that you're right in a way in that the Gruman style, basically what the the difference is, there's two types of reverse shoulder design. OK? And you only need to know these two right? I'll come onto the, the right hand side of the slide in a second. But what I want you to think about is this is this if you look at this one. So this always used to confuse me the difference between an onlay design and an inlay design. OK. And it's it when you think about it's not that difficult. An inlay design. Is this one here? OK. Which is your Mont style design? So see the grand shoulder was, was the first type of reverse shoulder replacement. There was now, if you look, the difference is clear, if you see here, the actual tray that supported the uh bearing surface is sitting within the shoulder. Yes, it's within the metaphysis. So this is an Inlay design, ok. The onlay design is basically where the tray sits on your neck cut. Ok. So most modern shoulder replacement designs now have moved towards an onlay design. Ok. But the traditional Grumman style one was an inlay. All right. Now, having said most modern ones are a non lay design. There are some inlay type replacements that are up there. So off the top of my head, the ones that I know that are inlays are things like. Uh so Lima doing Inlay design uh for their shoulder. Um and um the Dupuy um Delta Extend is a is also an Inlay design. OK. The, as Kareem said, basically, the difference is the way it articulates. Um So both the, the concept of doing AAA reverse shoulder replacement is, is essentially the same that really what you're trying to do is um increase the tension in the deltoid. OK. That's how this works. So, in the absence of a rotator cuff to move your shoulder, the deltoid, particularly the anterior aspect of the deltoid can take over most of the movement on the shoulder. Now, to make it it powerful enough to do that, you need to tension the deltoid. OK. So the concept of a Grumman design with it sitting underneath which is this this medial glenoid, medial humerus, OK? Is if you see where the original center of rotation was, which is here, what it essentially does is it in intermedial loses the center of rotation, thereby increasing the tension within deltoid. OK. So by shifting that down, you do increase the tension on the deltoid. OK. Now, as as designs have progressed, um and biomechanical studies have been done, there's been a realization that actually offset is probably just as important. So there's only so much you can inferiorly an implant by before you end up putting too much stress onto an the cranium. OK. One of the commonest issues with a um a reverse shoulder replacement is is over tension with the deltoid which then causes a cranial failure. OK. So most on uh most onlay designs now have this concept again of of of a later um humerus. OK. So what what we end up doing with this is we we're increasing the deltoid wrap. So you can see the difference between the first one, the media, the gram one which is the medial glenoid, medial humerus where it's quite flat. But if you look here, you can see that with increasing offset, you get this increase in deltoid wrap, OK? And the deltoid wrap is felt to be important in terms of improving the power of your movement. OK. Obviously, if you, you, you can see if you lais the humerus, you do get increased deltoid wrap. That's basically because the remnant of the tuberosity is causing that to come out. If you lateralize the glenoid as well, you get mega deltoid wrap, OK? But you don't necessarily need that. So somewhere in between where you have a bit of like me, a bit of inferior and a bit of later is probably the best. Having said that if you look at papers, what do you think, papers say against inlay versus onlay and no difference between the two? Yes. So there's no functional difference between the two designs. OK. Um But the, the there is there is a a known uh decrease in complication. Um What complication do you think you would get with an inlay design? So let's look at the picture a here that medial glenoid, medial humerus. What's the potential complication with it that you would avoid with electrolyte stem? No notching? Yeah. So what notching is basically is where the implant if you look there that's basically sitting right underneath the inferior aspect of the glenoid neck. So what you end up with is this wearing away underneath the implant? OK. Really bad notching is where you can end up coming right the way into it and then it fails from that thing. So with a with a onlay design that's naturalized, you can see that your instance of notching would be reduced. It's not impossible to get notching, but it's significantly reduced. So papers, there's a systematic review looking basically at on lay versus inlay designs. The the the only difference that was established was that there was a lower degree of not seeing women inlay design over a on late design. Ok. So you talk to people who use onlay designs, they say they're amazing. You talk to people who say that they use inlay designs. They'll also say they're amazing. OK. Who's right. Don't know. But um it's whatever you feel comfortable with. Ok. So you can see now that, that you, there's some advantages again that you're preserving the next shaft dangle, this obviously changes next shaft dangle. There's not much difference between the two, but just to be aware that the essentially, if you asked about onlay versus inlay designs, that's the essential principles of it. OK. Does that all make sense? You look better? Not doing good. OK. Excellent. All right. So what are we correcting? So it really depends on the indication for the shoulder replacement, doesn't it? OK. So the principle, as always, as I said to you earlier is no different to doing a hip, a knee, whatever you're trying to restore normal anatomy. OK. There are some slight differences between reversing anatomic shoulders. That's basically technical uh uh issues and there are limitations of what you can correct uh in term based on the morphology of the glenoid or humerus that you're looking at. OK. So I want you to remember all the way through that we're trying to restore normal anatomy. OK. Right. So I got, I got my, I read my feedback last week, I was told no, not enough cases. So guess what? It's gonna be case based today because that's what you asked for. All right. So for a 68 year old gentleman who's come to clinic to see you, he's had shoulder pain for about two years. He's had a progressive reduction in his movement. No history of tra me. He's otherwise fitting. Well. Ok. So Maria Co I can see you and I know the test is coming. Um So based on what we talked about last week, how would you go about assessing this gentleman? So history examination and then, ok, imaging, in terms of history, I want to know hand dominance job age, hobbies. Yeah. Past medical history that will influence decision regarding surgery and medication associated with that like major cardiac um problemss or lung problems or diabetes or immunocompromise. Um in terms of medication, steroids and anticoagulation mainly. Um then obviously allergies that might, might preclude surgery in terms of examination, I need to examine this patient through general assessment, look, feel and I will look if there are any surgical scars from previous intervention to the shoulder, he had no previous on his shoulder, then I'm going to palpate and check if this um pain is originating from, for example, ac or shoulder or around the shoulder girdle. Then I'm going to screen for the range of movement and then assess the the range of movement. I would be particularly interested in extend rotation to check if uh if the exter in the rotation is limited and then if it's active or passive, if it is passive, most likely there is a block um which is a structural block. Um then I will assess the rotator cuff because it's very important in, in terms of management. What type of shoulder replacement are you going to offer? And then I'm going to assess the deltoid function as well because in case the rotator cuff is gone, you rely on the deltoid and axillary nerve to, to put the reverse in. And then I'm going to obviously check if there are any stigmata of any disease, which will put me at um in the position where I cannot do arthroplasty, but I need to think fusion. Um And then obviously the the neur uh neurovascular assessment of the li to make sure that is there is good nerve and vascular supply. In terms of imaging, I would start with uh straightforward x-rays of the shoulder looking for stigmata of particular type of um for arthritis, for example, um if it is a rotator cuff arthritis or is a primary O A or is a Charcot disease, the x-ray is going to give me an idea about if it is osteoarthritis or if the joint is completely preserved, then I'm looking into other stuff like frozen shoulder or other causes for stiffness. Once this assessment is done, then I will need to check the rotator cuff formally either doing an ultrasound or doing an MRI if I then consider that there is a severe osteoarthritis, which might need surgical treatment. The next step would be to ask for a CT scan to check for the glenoid bone stock and the glenoid version. So then I can plan my surgery accordingly in case I have, um, a severe glenoid retroversion, I may need to use augment or to, to plan the replacement in that sense. Ok. Fantastic. Well done. Mi That's brilliant. Um, so yeah, don't, don't be caught out just thinking, er, that, you know, you've got to rule out other causes, like we said earlier, er, like frozen shoulders. So, yeah, very good. The examination is important. The key things I wanted you to mention were about the rotator cuff cos as you said, that's key to decision making. This gentleman's right hand dominant. He is still, er, working, he, he does a bit of manual work really, um, sort of lifts, not particularly heavy things, but it's quite repetitive, kind of manual work that he's doing. Ok. Um, so yeah, I can't think of anything else really from what you've mentioned, it's the cuff is the key thing, a range of movement checking that there are no other causes. Just be a little bit careful in the exam. Don't, don't start, er, Piking, their interest by mentioning things that the rarer causes like Charcot shoulder because that might lead to some uncomfortable questions about Charcot shoulder. So stick to stick to common things to start with and then wait for, you know, don't, you don't have to fire everything off in one go. Just wait, you keep that in your back pocket, just wait for the imaging that you've correctly asked for. Ok. So you're quite right in clinic, we'd get a shoulder uh, x-ray for this gentleman. So these are his plain films. Ok. So do you want to just, uh, you say, well, Maria, we carry on. So do you want to tell me what, what you can see on this, uh, these radiographs here? And so this is the A P and um, um, axillary view of the left shoulder. There is, um, there are clear signs of osteoarthritis. You can see that the joint space is limited. You can see that there is a start of forming an inferior osteophyte which, um, um, appear usually in, um, in, um, uh primary OA. And there is, uh, there are some signs of central erosion um, in the glenoid which all are, um, you know, significant for uh primary O A. Yeah. OK. So, yeah, I don't think anyone would disagree with you there. It looks like primary O A, doesn't it? The head appears to be well centered as you correctly said there is AAA goat's beard osteophyte at the bottom. It's not impossible to get those with a cuff arthropathy, but the head would be in a totally different position, right? As you said, yeah, you can still get an inferior osteophyte because it, it will articulate and superiorly wear. So it's not possible to get that. But you're right. That's a classical image for, for primary O A, isn't it? Um based on that axiliary x-ray, if you had to hazard a guess at what, what would you say his classification is? So, I think there is a bit of uh retroversion of the glenoid surface. So probably um is A B two, maybe B two maybe. Yeah. OK. Um So, yeah, I think you're probably right. Can you see here this is the glenoid margin here. It looks by concave, doesn't it? So we're lucky with this one because they've actually done a decent axiliary view. All right. But often you can't get that. Would you be confident, as you said, would you be confident just cracking on and sticking the reverse in that? I have ac to measure retroversion? Yeah. And also check the stock, the bone stock of the glenoid. Yeah. So what they'll try and do in the exam is talk you out of something? OK. So that you, you mentioned CT to er me earlier when you were telling me how you're gonna manage it, but they'll say that's crack an axillary view. What's wrong with that? You can see there's enough bone there and you know, it's a bit retroversion. Why would you, why not scrap on it? Doesn't look that bad. All right. But stick to your gardens. Go for your CT, as you said. So that's CT scan. OK. So given you a selected slice there. All right. Yeah. So you can see now that there is a bit of retroversion, probably less than 20 degrees, probably around 10, 15 degrees. And there is a bit of the bone stock is deficient on the posterior wall with lots of cysts. So that my, you know, in the back of my mind, I'm now thinking how we're going to reconstruct the glenoid and if we need to use any augment or not. Ok. So I'll tell you the, the, the measurements for this one, he's got a 15 degree retroverted glenoid. OK? That's, that's, that's what the measurements say when, when we put it through the thing. So how would you, what's your thoughts about that? So you, what are your options basically? So all the time the treatment osteoarthritis starts with non operative management as per nice guidelines, activity modification, pain relief, physiotherapy to increase the the function of the deltoid and rotator cuff muscles first and then can go further with providing some steroid injections for pain relief initially. And when all the non operative management was exhausted, then you can talk about the surgical management. In terms of surgical management, you have arthropathy, arthrodesis. This patient is well enough to, to have an arthroplasty done. But now, in terms of arthroplasty depends upon the condition of the rotator cuff and the deltoid, if you're going to go for an anatomical one or a reverse one, if the rotator cuff is intact and is confirmed by the um MRI or the ultrasound, then you can proceed with an anatomical one while if the cuff is completely gone. Um And you rely on the deltoid, you can then discuss reverse. If both of them are gone, then the arthroplasty is out of question. And the, the, what's left is then fusion or just debridement of the joint and buying more time, right? Ok. So his ultrasound scan, uh it's difficult to do an ultrasound scan on him. So you've asked for an MRI, but they said can't do an MRI waits too long. I can tell you enough of what you need to know from the ultrasound scan. But as is always the case of our Fritts shoulders, they put the caveat in saying, er, study is limited by patients inability to move shoulder. Um, but their feeling is that the greatly the cuff is intact, there's possibly some small changes in the anterior aspect of sup supraspinatus, but which they say may or may not be a partial tear. They can't really tell because the patient's arm doesn't move very well. So what, what has she got? He's 68 still working, looks like concentric O A on the, er, on the plane films. Um, he's got a, we would think probably a ab two glenoid though with about 15 degrees of retroversion. What's your thoughts? Uh Yeah, I mean, um the clinical examination is gonna also evaluate the rotator, the rotator cuff. But I mean, even if there is a very small um tear in the supraspinatus, that is not a contraindication for um anatomical um shoulder replacement. So I will consult the patient towards an anatomical shoulder replacement. Ok. All right. Let's have a look. So, reverses that anomic. So there's been a massive increase in, in reverses in the UK in recent years. So it's about 400% increase. I think it was in the last 10 hour report. So it's massive. So what are the advantages? So you say you're saying you're gonna cancel this patient for an anatomic over reverse? But what's, what's the advantage of one over the other? If, if there's 400% increase in them? Why? You know that, that's, that's a lot of reverses going in. That's, that's basically everyone's practice, isn't it putting reverses in? So, so why would you even consider an anatomic? What's the advantage of one over the other? So, an anatomical um shoulder replacement will maintain the biomechanical of the shoulder and will maintain the function of the muscles which are still working. Plus um in in case of the revision, you still have um the option of revising to um reverse shoulder arthroplasty. When the rotator cuff is not going to be functional anymore, there is even the possibility I think to put an anatomical shoulder replacement which has um um of plate which then can be exchanged to reverse one. I think when the time comes that rotator cuff um is is gone. So probably I will look into that as the patient is 68. Um So it's gonna, in time it's gonna progress to rotator cuff deficiency. So probably I will look into that one where you can change the platforms when the time comes. OK. So you use a platform stem, are you? OK. Um So what are the potential issues with platform stems if we go back to what we talked about earlier when I showed you two different types of shoulder replacement. So the advantage is that you can then change it without the uh destroying more bone stock by removing all pro this and putting a new one. And the disadvantage will be that it probably is a modular type of implant. Therefore, all the time when you have modular implants, there are risks associated with them like corrosion and uh lysis and maybe loosening of the components in the bones. Yeah. So yes, maybe. But actually the main issue is that if you think about back to the neck cuts that we talked about earlier. Yeah. So a lot of the implants that you use uh that are modular tend to be inlay designs. OK. So again, off the top of my head, the Lima one is the one that the SMR is the one that springs to mind, that is the sort of modular one that allegedly you can convert to, er, from an anatomic to a reverse and I'm sure you can do that. But if you think about the, the, the angles that you're talking about, which you cut, um, you, it's often that the, the, the mechanics are not quite right with it because you're, you've, you've set it up in the first instance for an anatomic, which as you said, is biomechanically different, er, where you're relying on the rotator cuff to maintain its function, whereas it reverse is relying on the deltoid. Now, if you're, if you, I'm, I'm not a massive believer in that, that you can do a modular exchange without, without compromising something that you're trying to achieve. Ok. Um I'd also say that often if you have a rotator cuff failure, what tends to happen to the humeral head? So is there is no more sling on the top of the humeral head? Therefore, loses the vacuum effect in the glenoid, humeral head starts migrating superiorly. Yeah. So you get loss of superior restraint, as you said, and it starts riding up into the cra now, if you've left some, if somebody's come to you with that issue, after you've done an, an atomic rotator cuff failure, they don't get operated on quickly necessarily, are they? So by the time you get to these patients, often they've shortened up quite significantly ok. Um, it's the same as somebody with severe cuff arthropathy. So, actually trying to get the shoulder down. Um, and, um, you know, trying to get the shoulder actually down and into a position where you, where you're now inferiors it, whereas before you were just having it cut at a normal, thick, at a normal level, um, is quite difficult if you rely on the original cut that you did for an anatomic shoulder, which is essentially just taking off the joint surface and leaving the cuff insertion on. Um It's very difficult actually to get a shoulder that's superiorly migrated like down and it, and it in joint without causing some sort of issue er if you don't re cut. So that's another downside of trying to use a modular component because often you have to re cut anyway. All right, because you, you to the only way to sho to get a shoulder back down is, you know, if you can't reduce it is to cut more bone off the humerus. OK? You can't, there's nothing you can do on the glenoid side, you have to cut more bone off the humerus to reduce it if you're converted to rever, right? So from experience of, of trying to use modular stems to get them down, it, it doesn't really work often when you're revising these, you end up having to do a recut anyway. In which case, you might as well just take the so better stick with anatomical and then when it fails, reverse, we'll come on to some ways in which you can, which you can make your life a bit easier doing, doing rever. Now I'm looking at someone in particular, is there anything any evidence at the moment for one over the other, in the, in, in age groups around this age? Because that's the big debate, isn't it? Somebody with an intact rotator cuff, is there, should we do a reverse? Given that the risk is Maria says, is cuff failure, that's the predominant er, issue. But the, the advantage being potentially better movement or do you just go reverse which eliminates the possibility of a revision for cuff failure? But are the sacrificing potential improvement in movement? Now, is there any evidence or any evidence being gathered out there about that at the moment? Probably there is some, but I can't, I know Mr Te knows they, so there's the Rhapsody trial which is happening across the UK and Australia and that's looking at people with um intact rotator cuffs over the age of 65. Um and they're being randomized to either anatomical or reverse. Um because the idea is that people are waiting, well, the idea is that people will wait longer to have their shoulder replacement done. But the concern is that um if people's um, rotator cuffs are going to end up failing, then should they just do a reverse in the first place? Um So randomize. Yeah. So it's very good. We're doing that here at the West Suffolk. So it's essentially as David says, we're looking at um, intact rotator cuffs and then randomizing patients who've got that to either reverse or an anatomic. Ok. Um So it's a good question and, and nobody honestly knows the answer as to which is better. There is limited evidence at the moment that actually reverses in younger patients are probably not as bad as everyone thought they were. Um But I think most people's concern as Maria said, is that revising a reverse shoulder replacement is diff more difficult than revising an anatomic to a reverse if you see what I mean. So as with anything when you're doing arthroplasty, you've always got to think about the subsequent operation and the subsequent operation after that. OK, particularly in younger patients. So if you asked about evidence, you can say nobody knows there is a study at the moment that's looking at anatomic versus reverse. It's a multicenter uh blinded, randomized controlled trial, uh which is an international one. So the patients in that trial won't know for two years what operation they've had. All right. And it's looking at um functional outcome measures pre predominantly um as well as you know, the usual stuff like failure and revision. OK. Right. So, so you've, you've opted Maria for an anatomic. So we've got, so you've mentioned that you, you've done a lovely assessment of the radiographs and you've told me that there is, there is some glenoid bone loss there. So I want you just to think about now, Maria, what, how are you gonna manage that Glenoid bone loss? Ok. So you mentioned augments there? Um And, and what are you gonna do on the humoral side? Ok. So do you want to start with the Glenoid? Tell me, tell me how you're gonna manage the glenoid. So we, I've, I've given you the number, it's 15 degrees retroversion. And how are you gonna manage that? So, in terms of the glenoid, you can do two things. One level it up by taking off the anterior glenoid and level it up there or second, build the posterior wall by either bone graft or augment. OK. So, yeah, that's absolutely right. So which one are you going to do? So given that it is only 15 degrees, probably I will shave the anterior part of leaving the augments for more than 25. OK. All right. So, so we'll come on to that in a second. Yeah. So you're gonna eally ream to correct the version by taking more anterior base that, that's your plan. OK. Fair enough. And then you're going to use the standard implant for that. Yeah. OK. What are you gonna do on the humeral side? So, on the humoral side, um going to going to cut um the, the, the removing all the osteophytes and especially the inferior beard one. Yeah, And after that, I'm, I'm going to measure, but making sure now that I've removed more glenoid, then I need to make sure that, um, the offset is still correct. Ok. So your offset is pretty much determined by your, well, it's determined by your canal really, isn't it? It depends, it depends what kind of implant. So what I'm really asking is, what, what type of implant are you going to use on the humoral side? Are you aware of any different types of options for the? So they can be the ones which are stemmed and there are ones which have, they are unstained or have minimal. Yeah. So there's three types. Basically, there's stem less, OK? Which is the ones that don't have a stem, there's a short stemmed one which does have a stem but it's shorter than the standard stem. Ok. So you, yeah, so there's, there's advantages to all of those and disadvantages. Ok. So the main advantage of using a stem, um that you have less bone to take away if you revise. So you your bone preserving. So most of these stimulus or short stem options are bone preserving. So as I said, you're thinking about revision. If revision is a concern of yours, then you could say if the meta bone is, is, is OK here, would there'd be an option to use a stimulus or short stem device which would then give me the ability to, you know, more options in terms of revision, if the cuff was to fail at a later date. Ok. You might have to use a stem. I'm sorry. So I've seen more stem, less prosthesis. So probably so stem definitely have a place. So your indications for stem basically, when you can, when, when the bone won't, won't adequately hold a stem list. Ok. So you might have to use a stem still. All right. Um But again, there's different options. There, there's cemented, uncemented advantages of ba cemented is if you can get an uncemented in, it's easier to revise. Um, because getting anything out of cement is an absolute misery, right? But sometimes you will have to use a cemented one. Ok. Good. So, I think what you said to me is that you're gonna eally ream but a standard glenoid in and then try and go for a stemless design for bone preservation on the humeral side. Correct? Good. OK. All right. So glenoid retroversion. So there, there's some rough numbers here. OK. Which give you rough ideas of what you can and can't get away with. All right. So less than six degrees, I've already told you that 2 to 4 is, or anywhere up to 10 is basically normal. So if it's sort of less than 10 degrees, I would say 6 to 10 degrees, I would, I would probably eccentrically ream it. Ok. Oh, sorry that, oh, so, uh probably you surgically remit. OK. Or, or just put it on fast because bear in mind that six anywhere between nought and 10 is, is probably ok. So that means a nonfat is just basically shove it where it is, right? You don't have to correct anything 60 or 11 degrees. So Maria, you mentioned augmenting if it was 25 degrees. I know I've given you given you the answer there. Yeah, I think you were. Yeah, I mean, I'd like to see that David and I did a case earlier where, where we, where we talked about what would happen with an augment and, and bad things would happen if it was that, that, that retroverted. OK. So if um if you're going to augment uh Maria, so why, why over 18 degrees are we going for a B A bone block rather than an augment co they make augments up to, they make them up to 18 degrees. So why, why not augment it with metal? Well, I the the, the only way I can think of, I, I don't know, but I can just presume that the bigger piece of metal is gonna erode even more in the left over bone. So you would hope not because the implant should be stable, right? So if you put an augment in it, the the whole thing should be stable, right? So there's two schools of thought really um if you can augment with metal, you've got less interfaces. OK? So if you use bone, you've got the interface between the implant and the front part of your bone block. Then you've got an interface between the bone and the bone. So the, the, the, the grafted bone and your native glenoid. OK. So you've essentially got three interfaces. So three points at which you can have failure. If you use metal, you've only really got one point of failure, which is between the implant and the bone. OK? Now, there is evidence um to say that any er, that I um augment, sorry, above eight degrees have a higher rate of failure than those of eight degrees or less. Ok. So most people would not, er, use a metal augment o over eight degrees. So when you look at portfolios of implants, you'll see that most, most of the companies don't make anything over eight degrees. Some do. Um but there is the, the evidence is that anything augmenting over eight degrees with metal has a higher chance of failure. Ok. And that's just mechanical failure of it because you're essentially putting quite a big lever on, on the, on the implant. Ok. There's, there's loads of other factors such as how that actual implant actually attaches into the bone, but anything over anything over an eight degree augment is not recommended. Ok. So if you think about what you said, if we're going, saying it's about 11 to 15 degrees, we've sort of come to a compromise there, Maria haven't. We, we said we, we a little bit, we did a little bit of reaming and we're, we're sticking a, we're sticking eight degree augment in. Ok. So you can imagine if you weaned off a couple of degrees. Um, saying got it down to about, I don't know, 12, and then you put an eight degree augment on your overall correction is gonna be back to four degrees, which brings us back to normal. Ok. Um, 18 degrees needs some sort of bone. OK? You can imagine that otherwise you, you know, you're resting something on it and it's a lot of force going for a piece of metal, er, to do that. Er, but we'll come on to that in a little bit. Ok. So, so far so good Maria. OK. We've, we've reached a compromise. All right. So we've talked a little bit about this is just so this is just the implant that we use at the West Suffolk. So this is what a stem less design looks like. Ok. So this is a big trip. Trabecula metal cage. All right. You in this little hole here, you can pack some bone graft in but it, it grips like a, a bug of this thing. So it's, it's very good and then you can, you can put a head on top of that. OK? Um This one is a, is a stemmed prosthesis. This is a press fit stem. All right. You can see there that it's got a metaphyseal coating. Um uh but then a smooth uh smooth stem underneath that, OK. We'll come on to the reasons uh uh we'll come to about meta bone coating a little bit later, but that's essentially the difference between the two. All right. A short, a short stem is somewhere in between. So they normally stop roughly where that line is. OK. The short stems um companies do make them, it depends on your preference. Um The stimulus is definitely easier to revise. OK. So Maria, this is what we, this is what I did. I followed your advice, right? Yeah, I did a stem shoulder replacement for him and I, I did, I used an eight degree posterior augmented glenoid, right? So if you look where we were beforehand, he's still well scented. All right. So I haven't really done it. His cuff looks to be OK. Um The main thing I wanted to put up was just to show you. Now, if you take this Friedman's axis here which shows the center of his glenoid, his head is now well centered. OK. So that's what we're trying to do. So essentially through what you said, Maria, we've arrived at, at what we wanted to achieve, which is correcting normal anatomy. OK. Sorry Mr Dun Can quickly. So is the, the base, is that all poly then? Er what on this, on this design? Yeah. So, so on this, this is a polyethylene er com component but we have, there's these metal pegs on the outside on this design, er which basically stock rotation and then this the main point of fixation with this is this, this, this um again coated peg which grips in the bone and then allows bony in great. There's many different designs and which we'll come on to a bit later. But, but yeah, this design in particular works by, by gripping on those points of fixation. OK. What's it called? The which company is this? This is Exac Tech. This one is an equinox. So, yeah, thanks. All right. OK. So that's that one there. So we're done, Maria. That's really good. OK. So you've talked uh so hopefully by doing that like that, we've covered quite a lot of principles there. So we've covered how you manage you, how you get your correction, what the options are on the humoral side. This is your basic standard thing. OK. All right. Good. Move on. So why did your shoulders fail? All right. So traditionally, the Glenoid has always been the weak link. So that's, that's always been the, the area where the shoulders fail. It's never really been the humoral side. OK. But there are some, there are some examples of failure on the humeral side. But why is it that the Glenoid is the point of failure? Uh Walker Horse effect? So the rocking horse effect. Yeah. So we'll come on to that in a minute. That's the main reason it was basically instability of, of, of the glenoid components. OK. So there's, there's broadly speaking, several different designs um for, for Glenoid. So the original Glenoid were essentially um keeled design. So a bit like I'll show you an example in a minute but a bit like a ship, you know, the bottom of a ship where you've got a keel underneath it. Um And there was, it was like a slot basically that you cut into the bone and put it in. Now, they just used to rock themselves loose, which is that rocking horse effect. So as you articulated, it just sort of rocked itself and worked itself loose like that. OK? Um People then came up with peg designs. OK? That didn't mean that they were the cure all for everything. OK? They still had a similar effect um in that they did rock but they rocked side to side and then eventually loosened like that. OK? Um To overcome that people then decided to put metal on the back of Glenoid. So Metal Back Glenoid became a thing thinking, OK, well, if it's the poly, that's, that's not really, you know, because you're essentially cementing a poly in there that, that's, that's not particularly stable. We'll put metal on the back uh and then shove some screws in it and that'll make it better. Now, unfortunately, Metal Black Glenoid at a massively high rate of failure. OK. That was basically deal with contact stresses through the poly probably because we weren't correcting version. So early shoulder replacement designs didn't really have any option apart from EENT reaming. Um because augments didn't really become a thing until about 2014. So, so you, you didn't have the technology really to, to be able to overcome massive retroversion. So um a lot of the metal back Glenoid had um acentric polyethylene wear which then caused aseptic loosening, which then caused failure of the, the base plate. You then get erosion into the base plate. Mela It was a nightmare. So metal back Glenoid um basically disappeared. But you're right, it's basically biomechanics, OK? You're putting a lot of contract force if you think about the, the actual um a normal shoulder, for example, you've got an enormous humeral head with a massive range of motion in it going across something that's a bit like a golf tee. So if you balance something on top of the tea that you're then expecting to take all that force in a multidirectional way, it's, it's not going to not going to hold necessarily. OK. So we talked, I think the bill mentioned about the um rock horse phenomenon. OK. So this is essentially what he's saying. So as you can see though that you start off when you put these shoulders and you think fantastic that's in the middle, right? But what always happened is that they always subluxed out the back, OK? Because you know that's what it wants to do so it overcome. If you're not correcting the anatomy as Maria did with her case, you'll end up in a situation where, where you have EENT loading of the implant. Ok. So if you see it on the keel one there, you can see that this line here shows how it tilts it essentially preferentially loads the back which then causes it to lift off. Ok. And as that happens, as I said, it just rocks itself east within the cement mantle. OK. Now, all the while, of course, you're getting poly debris generated by that. OK, which then causes um you know, your bone resorption around that and what is the affect joint space? So that's the, that's the back of the implant. So all of that interface where you've, where you've ringed and cemented is effectively a joint space. You end up with polyethylene debris getting in there which then exacerbates the loosening of the implant. OK? Pegs. So again, pegs weren't perfect. OK. The idea behind pegs was that you, you gave multiple points of fixation rather than a single point. OK. Um And you can see that it sort of makes sense, it should be a little bit more stable, but you can still, if you don't correct anatomy end up in this situation where you end up with a rock horse phenomenon. Now, the implant, as you earlier, the the there's evolutions of everything. Um Now, my rationale behind using that implant is that you saw the cage in the middle there? OK. So that thing, uh grips like nobody's business. So actually there's some early evidence that the cage ones have a lower rate of failure, right? But I don't think it's a question that's been fully answered. All right. Um, but the thing to be aware of when they talk to you about, if they, or if they talk to you about, um, designs of glenoid is essentially the peel peg versus keeled Glenoid debate, right? And this is a, um from this Children elbow uh surgery journal, uh which I think was published in 2019. And it's basically a metro analysis and systematic review that essentially says Kill Glenoid is rubbish. Pe glenoid is better. But this, the, the, the only reason they're better is that they have a lower rate of revision. OK. So that's essentially what that, so if you need an evidence for that, just say that really? All right. Ok. So that's why the glenoid tend to fail. So that's the traditional mechanism of failure. Is that Rock horse p, the one that Neil mentioned? Ok. But that does that make sense to everybody? It's just, if you, it, it all comes down, it's a bit like a hip again, if you don't correct the anatomy, you, you're gonna end up with, with problems. Ok. So this is why it's important to go back all the way back to the start where we're, er, thinking about our wart classification, looking at our, our retroversion, looking at strategies. We've got to correct that depending on those numbers that I gave you earlier. And then also thinking about the next operation that we're gonna have to do if it all goes horribly wrong. All right, let me just see what's next and I might need a copy. So other measures that we've already touched on in a aseptic loosening is a me mechanism of failure. Yet everyone knows what that is. So it's, it's basically activation of, of your um neutrophils which causes a massive inflammatory response. Uh The consequence being the activation of the osteoclasts which then um causes resorption of bone. OK. So that's, that's effectively the mechanism and that's your basic science. Never forget infection. OK. So anytime you get some sort of failing implant, always, always, always start in this is infected until I can prove otherwise. OK. So if you get a failing implant shown to you in an exam, always start with your basics. So I'm gonna assume this is infected until I can prove it's not infected. Uh So make sure you mention the things, obviously, you cover most of it in your history, but make sure you're mentioning things like your blood test, your cr pr or your white cell count. Are you gonna aspirate the joint? Yes or no. So, you know, uh all those things that you want to work up because bear in mind that if you're getting taken down the pa the path of a failing implant, irrespective of where it is in the body. Um They're, they're wanting you to start to talk about revision options. Ok? So you'll definitely get a big, yeah, if you uh if you start saying I'm gonna shove something in and you haven't excluded infection. So infection first and then wait for your major failure after that. Ok? Just have a quick sneaky peek at the next slide again for an hour. Now, um I'll tell you what, why don't we grab a quick coffee? Is that all right? Shall I give everyone a quick? Uh How long do you want? Five minutes? 10 minutes?