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Reverse Shoulder Replacement (Part 1) For Postgraduate Orthopaedic Exams
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Reverse Shoulder Replacement (Part 1) For Postgraduate Orthopaedic Exams
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Segment:0 .
DAVID HUGHES: Chertsey in Surrey. And today he's going to give us a talk on reverse shoulder replacements and how the complications in dealing with those. It's a really key topic because at the moment we can see that the amount of people requiring reverse shoulder replacement in trauma for example, is increasing.
DAVID HUGHES: So it is a hot topic. So please do pay attention. So without further ado, I will leave you with Mohamed.
MOHAMED IMAM: Thank you, David and thank you, everyone for attending this topic, as David has rightly said. This is actually part two of the talk I gave a few weeks ago on reverse shoulder replacements and now we're going to talk about the complications and how to manage these, especially that now reverse shoulder replacement is a very popular procedure.
MOHAMED IMAM: So, all of you, all of us are involved in it one way or another. And so it is expected it will be coming in the exam more and more and basically, it's a common questionbecause it is a common procedure. What would happen is that you might have Viva stations or basic science stations talking about complications. Some of it might be a bit technical, but I'll just give comprehensive so take whatever you'd like to take and leave the rest.
MOHAMED IMAM: So just a few, the first few slides are just to revive your knowledge about reverses. So we know a key concept describing the mechanics of the normal shoulder relates to the concavity compression, and that's what Matsen et al describes this technique as a ball sitting in the concavity of a table. And so the greater the depth of the concavity, the greater the displacing force needed to dislodge the ball for a given compressive load.
MOHAMED IMAM: And so in the normal shoulder, the rotator cuff muscles provides a compression out of the compressive load, and that subsequently, when lost in rotator cuff deficient shoulders, this will lead to an instability resulting from the unbalanced muscle forces on the glenohumeral joint leading to proximal migration of rotator cuff, then arthroplasty. A second biomechanical point, which was proposed by Madsen and Leavitt as well, is the concept of the glenoid center line.
MOHAMED IMAM: And when you - in a normal glenoid the center present line perpendicular to the articular surface of the glenoid and that actually serves as an important landmark in shoulder biomechanics. When you lose that line, you lose the fulcrum, the deltoid is shortened and that can lead to a lot of problems. And the classic cuff tears obviously can lead to different complications in shoulders.
MOHAMED IMAM: And luckily now, with the advances we're having, we have the option of shoulder reversal, the replacement, which actually serves as a solution for a lot of problems we see. And that's why we are now doing more and more shoulder and reverse shoulder replacements. And if you look at the National Joint registry, you'll find that a huge number of shoulder replacements are being done every year.
MOHAMED IMAM: Actually, it's a number has doubled more than once from 2013 till now. The problem we had with shoulder replacements was the complication rate. And also of all the advances over the years, starting from the first shoulder replacement done by Charles Neer, who many would regard as godfather of shoulder replacements who tried to reproduce a normal shoulder mechanics.
MOHAMED IMAM: Initially, however, the problem was always in rotator cuff deficient shoulders because this was associated with high failure rate and everyone thought about the solution, which is actually achieving a stable center of rotation. And over the years there was important alterations from different designs, mainly influenced by the hip. So very successful hip replacements, however.
MOHAMED IMAM: Basic principles here you couldn't really apply and the problem was always losing the fulcrum and an inability to achieve a stable center of rotation. And the main problem associated with all these designs that was modified over the years was the inability to achieve a stable center and having excessive torque and shear forces at the glenoid component.
MOHAMED IMAM: And it was until this man in 1985 proposed the basic concepts of reverse shoulder replacement by having a medialised center of rotation and distalised center of rotation in the humerus. That decreased the shear forces and create a greater lever arm of the deltoid, putting the deltoid at a biomechanical superior position. And so the patient will be able to achieve a good range of motion
MOHAMED IMAM: ultimately. However, this is without assistance. Obviously you can see how to modify from the first picture on the right, through to the left side by increasing the distalisation of the center of rotation. We now use the reverses for trauma initially, and that's mainly because we realized that it is if in certain cases, if the initial fixation fails
MOHAMED IMAM: of the salvage procedures involving reverse shoulder replacement that this is a paper that we published from Zurich. And so they are associated with drastic complications. And more and more now, because we do more reverses, we are seeing more complications. And also of all the advances we have nowadays with Blueprint and with other custom made implants, we still are seeing more complications.
MOHAMED IMAM: So first, what was the problem with initial designs by Grammont? There was a few complications that was very common, including loosening and launching and stability, which has been reported extensively in the literature, arm length discrepancy and in order to modify and decrease the risk of complications, this guy Frankel from the US proposed having a lateralised center of rotation, either through the glenoid or through the humerus, and you can achieve the either with a metallic augment or a biologic augment.
MOHAMED IMAM: And so either by and that old mainly was aiming to decrease the complications associated with the Grammont design. And this is a by when you say would you use a bone graft to lateralize the center of rotation. There are different tips and tricks you can use on the humeral side as well as the glenoid side to achieve lateral luxation. So what is and that has actually made a lot of systems available to all shoulder surgeons globally with different implants and different concepts but didn't reduce complications
MOHAMED IMAM: and that's what we're going to discuss in the coming few slides. One important thing you have to know is glenoid lateralisation is not the right answer for everything because those patients will have reduced abduction and glenoid loosening while humerus laturalization patients will have reduced abduction as well as the risk of instability. So what are the risks and what are the complications we see nowadays in reverse shoulder replacement and how to manage these?
MOHAMED IMAM: So initial results by Pwllheli have revealed that there is a 15% complication rate in shoulder replacements, and this was published in JBJS America in 2006. But there is a big concern about this paper that 3/4 of the 7,000 total shoulder replacement were performed by surgeons who do less than two shoulder replacements a year. So we know it's not rocket science,
MOHAMED IMAM: we know that if you do less, the risk of you having more complications is high. And so with them, generally speaking, we know that these are the complications that can happen in any replacement we do in the shoulder. For anatomic, the main complications are glenoid loosening and rotator cuff dysfunction, while with Hemi, it's glenoid erosion, as well as rotator cuff dysfunction.
MOHAMED IMAM: But we will focus on rotator on reverse shoulder replacement because we are seeing a lot of this are done nowadays and a lot of these are being revised and presented to us with some of these complications. The commonest complications are notching failures either on the base plate or bone failure on the acromial side, as well as intraoperative glenoid fractures. We'll discuss them in details.
MOHAMED IMAM: We looked at 159 reverses and we reported similar complications in these as well and we're going to go through this in detail. Similar pictures are reported everywhere. Of course, whenever you're doing any replacement, this is a drastic complication you're thinking of. Personally, that's my experience. Either it is a hip, hemi or a reverse shoulder replacement. And so infection was reported to be around 1% of primary total, however, it is up to 5% in a reverse shoulder replacement
MOHAMED IMAM: and that's something you should mention in the exam. And mainly that happened because those patients have large dead space, because you extensive excision, you are undertaken, you have the liberty to take the cuff out, release the capsule, take you can take more bone out. Also, there is absence of living tissue cover, such as the rotator cuff. These patients are usually older population and there is a consensus nowadays among shoulder replacement, amongst sorry shoulder arthroplasty surgeons.
MOHAMED IMAM: Personally, I would think twice if I'm going to offer an anatomic to someone above the age of 75. If I see someone at the age of 80 with intact rotator cuff tendon, I'll be worried that this will fail. So I'll have a low threshold to offer them a primary reverse shoulder replacement. And also it is a viable and very valid vision option so these patients also have multiple previous surgeries.
MOHAMED IMAM: The commonest organism here is still staph aureus, but P acnes is a very common and very popular organism in shoulders. And the problem with infection and shoulder replacements and this is one of the papers you can easily cite. That doesn't come very clear because the majority of patients will have normal white cell count, normal ESR and normal CRP. So 75% plus of these patients will have normal inflammatory markers and will have negative evidence of acute inflammation when you take histological specimens.
MOHAMED IMAM: So this paper is actually a bit of an alert for shoulder surgeons, and that actually would be an indication if you don't have a proven infection, treat it as if it is an infection and you should be a bit more aggressive in shoulders compared with others. We have the same classification for infections here so if you find positive cultures at the time of surgery. I'll do the debridement, find, do the histology, find specific antibiotics and have a close clinical observation.
MOHAMED IMAM: If it is in the first 30 days, I'll go and use their procedure, their approach and many of what we follow in arthroplasty in shoulders is based on what we learn from our colleagues undertaking hips and knees because they have extensive evidence over the years. And so we'll approach that with their approach, surgical debridement and change of insert, if we can. In type III where it is more than 30 days
MOHAMED IMAM: there are two schools here. You can either deal with if it is less than two months similar to type II or proceed with two stage division with antibiotic spacer leaving the antibiotic spacer for two to six months. It depends on a lot of factors and if it is a chronic infection, you can either do oral antibiotics forever or if the patient is medically not fit or do staged revision. And then Christian Gerber who published work on spacers and a two stage revision.
MOHAMED IMAM: And we found that using antibiotic loaded cement spacer is efficient and more than enough for 90% of the patients. And actually, the other thing is that the best function is achieved if the second stage is a reverse shoulder replacement. So, if for example you have someone who had a hemi arthroplasty, which is clearly infected, you have a low suspicion of infection based on the publication we've cited in Journal shoulder and elbow and then you would go for two stage revision.
MOHAMED IMAM: If you leave the spacer in or if you do a second stage hemi, the functional outcomes is significantly less favorable than having a reverse shoulder replacement as a final stage there. An important function that I understand many people don't as important complication that many people do not really understand that much is not showing.
MOHAMED IMAM: And by launching we mean that there is a mechanical impingement between the superomedial aspect of the humeral insert here and the inferior scapular neck, as you can see there, and you can see on the right and why this is important. If you see here, it is also this was very common as well with the medial center of rotations, the original Roman style, because your center of rotation is medial and actually that can cause the notching in the inferior aspect of the glenoid neck here.
MOHAMED IMAM: And why you need to manage this, because there are risks and concerns with notching if it happens because Sirveaux actually graded them as it was there. It is limited to the pillar with grade one, which is usually not a problem. With grade 2 it will be in contact with the lower screw, and grade 3 it is actually over the lower screw and in grade 4 it extends under the base plate.
MOHAMED IMAM: And you don't need to be a shoulder surgeon to tell that great for you will be associated with market loosening of the glenoid. But does it have clinical correlation? That's something you can mention in the exam. Looking at 60 shoulders. There was notching in around 88% in one of the earlier papers looked at Grammont reverse shoulder replacement and that's a huge number if you think 90% of your shoulders will have a notching.
MOHAMED IMAM: So it's not uncommon. And looking at the newer designs, we found that it is actually 35% and actually we found that it doesn't affect scores at five years follow up. But others found that if you have notching and you follow patients for longer periods or periods of time, clinical scores might be affected. And the survivorship of the implant will be affected and Luca Faraud is one of the eminent surgeons in shoulder arthoplasty in France, so notching is a problem, especially on longer follow up, although there is debate.
MOHAMED IMAM: So there are others, there are some who say it doesn't actually influence clinical outcomes and some say it has really it actually has a negative influence. So I think we still need to follow this up for a longer period of periods of time in order to understand the problem. So what is the clinical relevance? As I said, others said it is a predictive value for suboptimal outcome and showing published that it might be an indication for revision in short term.
MOHAMED IMAM: Of course, as everything in orthopedics we need further research. So one thing you can be asked or you should know about if you're interested in shoulders is how to prevent notching. It is if you look at the video, I've shown you earlier, you can do things that would prevent the risk of notching in when you are operating on these patients and doing a shoulder replacement. One option is actually do
MOHAMED IMAM: But to have a sphere position more distal So that you can have less mechanical impingement and you can also increase the arc of movement. And that's a commonly performed technique nowadays. Second trick you can do is by having an inferior tilt of your giving sphere, and that would also increase the arc of motion and decrease impingement. Another op trick you have to mention, or you have to do, is to avoid excessive reaming so that you decrease the risk of idealization of your dreaming and your baseplate.
MOHAMED IMAM: And finally, possibly implant choice might have an effect because we know that lateralised center of rotation and the other technique, like having a bone graft or also what is known as piroarthosy, might decrease the risk of notching as well. So by having how can you have a lateralised center of rotation? One thing you can have a larger glenosphere if you're doing a shoulder replacement.
MOHAMED IMAM: Second option is to decrease the neck shaft angle. Or reduce the cup depth because that will decrease the risk of impingement. Or using an eccentric glenosphere. Or an angled insert which is a proposed trick, but not proven much. So there are different tricks and tips. Maybe not suitable for the exam, but it's worth knowing these steps in order to avoid the risk of notching.
MOHAMED IMAM: If you see a patient with a reverse shoulder replacement that you look at, the inferior scapula angle, assessing, watching and talking about these tricks and tips, which I think would be popular over the coming few exams. Another option, another risk as well, and other complications that we see, we see less in reverses is instability. And with instability, it is common in other implants like anatomic shoulder replacements, which is something you're likely to see in the exam.
MOHAMED IMAM: But I wanted to focus more on reverses here, but just quickly touching on that. A large humeral head can be associated with instability. Other factors include your rotator cuff balance, your subscapularis balance, soft tissue balance, deltoid, function and physiotherapy. Sometimes, if you're doing overzealous physiotherapy, that can cause problems. Is there a problem minister, in reverses?
MOHAMED IMAM: Yes, it is, but it's not as bad. But in some reports, it has been reported to be as high as 30%. So, exam approach like every other thing you answered in the exam as a day one consultant. There are patient related factors, surgical related factors and implant related factors. When you see these or any other joint replacement. What other evidence?
MOHAMED IMAM: The evidence says the chances of having instability after a reverse is higher if the patient is less compliant with poor deltoid function, patients with recurrent falls and prior shoulder surgery. And that's something in clinical or vivus you have to understand before offering a reverse shoulder replacement to one of your patients who is a recurrent faller. I had a patient with a fracture dislocation of the proximal humerus with an admitted patient is a frequent faller demented.
MOHAMED IMAM: I would have a very high threshold to offer a shoulder replacement there. Possibly one option would be supervised neglect because this was. But it's all about patient factors more than anything else. The other factors is surgical factors approach. There is I will talk about approach later on, but you can have other risk factors there related to position of components, which would be applied to any joint replacement humeral lengths discrepancy.
MOHAMED IMAM: Not an important factor here, dead space on having a hematoma. And I think deltoid tension is a crucial point here and also preservation of the soft tissue envelope. So what about the approach? Theoretically, it is said that you can have less instability with supero lateral approach because of preservation of subscapularis. The problem with a simple lateral approach is it's not excised
MOHAMED IMAM: so you can be putting a shoulder replacement in and you have a fracture and then it's very hard to extend the approach through the supero-lateral approach to pectoral. I can open the whole arm through a deltopectoral approach by going lateral to the humerus and as distal as you can. That's another risk. And the other risk as well is maintaining soft tissue balance and approaching the inferior glenoid.
MOHAMED IMAM: So in the exam there is no right answer, but it's worth knowing that. Also, having said that, there is recent evidence saying that there is no difference in stability, in stability, comparing the two approaches together. Surgical factors, so we hate to blame ourselves, but humeral length discrepancy which is important, which can cause a problem, especially if you're doing a revision or in a fracture case
MOHAMED IMAM: and that's why there are a few tips and tricks when you're doing a reverse shoulder replacement for a complex proximal humeral fracture in order to avoid placing the humeral component too low in those with humeral loss. So other aspects as well. Malposition of the components and usually we aim somewhere between 0 to 20 degrees retroversion, which are technical bits you can mention in the exam if you are discussing that deep into your Viva station.
MOHAMED IMAM: It's crucial to preserve the soft tissue envelope, also now there is some surgeons actually not very keen on reattaching the subscapularis Although, personally, I think still soft tissue cover on the components. Deltoid tension, if you increase the lateral offset, you can actually it's crucial to maintain and achieve the deltoid tension right, because the deltoid will be undertaking the function of the deltoid as well as the deficient cuff, which is done when you do a shoulder,
MOHAMED IMAM: reverse shoulder replacement. Other other aspects, which is the design aspects includes the humeral head side and side, sorry and those designs with lateralised center of rotation, some of them, especially if you're lateralising from the humeral side might be associated with instability. And finally, how to manage it? You, as everything else, you have to check, examine and assess the patient in the light of the best interest
MOHAMED IMAM: and then I would obtain plain radiographs and CT scan to make sure I rule out structural abnormalities, especially with base plate fixation failure. You have to identify that and component mal positioning. Remember the slide on the plus key evidence, always, always, always exclude infection. Why? Prevention is always better. It's crucial to assess the stability on table. These are two tests; the shuck test and the lateral thrust test but intraoperatively.
MOHAMED IMAM: This is a nice summary of all tests we use in order to make sure we achieve the right deltoid tension and the right positioning of the component. If you have a positive test in any of these situations, management options would be based on your assessment, especially when you put the trials in. I'm not going to go into the details, but that slide, you can take a look on later on.
MOHAMED IMAM: And then if you have a reverse shoulder replacement coming to you as the day one consultant in the first few weeks after surgery, I would try a close reduction under anesthesia and we have some time and immobilization. If I cannot do that, then you are, this should be done by a shoulder surgeon, obviously, but you have to do removal of soft tissue and feel to clean sphere because it might be causing impingement and causing instability.
MOHAMED IMAM: You can consider using a thicker insert and definitely correction of soft tissue problems like soft tissue abnormalities, humeral length, discrepancy and versions. That's why it's crucial to assess the problem before surgery intraoperatively as well. What, how can you, what you can do for humeral length discrepancy, Here's a bit of the technical aspects here. Well, you have to make sure how to assess how much discrepancy you have
MOHAMED IMAM: and then based on the discrepancy, you can assess and dictate the best treatment option in each of these situations. What about second options of failures here that we saw, a second risk of failures that we cited in our evidence that has been reported on multiple occasions. Baseplate failures. The good news, it is less common nowadays with the newer designs and possibly the commonest aspect and factors that lead to baseplate
MOHAMED IMAM: failure is poor initial fixation and loosening due to osteolysis and infection of course. If it fails, you can have patients with screw failures, patients with growth failure and baseplate failure. And actually the worse situation you can see, which isn't my x-ray, but I took it from Ali Navarni, my colleague, is dissociation of baseplate and glenoid sphere.
MOHAMED IMAM: If also another technical errors that sometimes happens while doing the procedure, is having soft tissue interposition or incomplete removal of the preferred rim of bone on glenoid. Other preventive measures which you mentioned and inferior health and obviously using locking screws, which we orthopedic surgeons are very, very keen on using nowadays.
MOHAMED IMAM: If it fails, I would go for two stage revision, if you're confident, you can go for single stage revision plus or minus the bone grafting. So, what is next? This is becoming more common. We see it in my hospital at least once a month nowadays in shoulders, prevalence is 1.6 to 2.3, and that's based on previous evidence. More and more are actually coming to us nowadays.
MOHAMED IMAM: Contributing factors for periprosthetic fractures, includes elderly population, weak bone quality, osteolysis. If you do excessive reaming of humeral cortex or if you do eccentric placement of the humeral component, and these are all aspects and factors, it's better you should identify as early as you see them. We use the Wright & Cofield classification, which is actually related to the Vancouver one, as you can see on the X-ray or sorry, on the diagram on the right side.
MOHAMED IMAM: With Type A, usually system is stable, with Type B, thus a fracture is centered at the tip of stem with minimum extension and Type C it is distal to the tip of the prosthesis.
MOHAMED IMAM: How to manage it. First, prevention is always better than cure, so when you are doing your procedure, personally, I don't want to use a hand support. Sorry, shoulder support like Kimono or Spider when I'm reaming because that can cause a fracture and it happened to me when I was assisting as a fellow many years ago. Also, you have to be extra cautious and avoid forceful
MOHAMED IMAM: external rotation. It's a reported evidence of having an intraoperatively noise fraction while doing a reverse is actually up to 10% and technical notes here, technical tips here, you have to start restart reaming before coming in contact with the bone. And also you have to be extra cautious when you are reaming osteoporotic bone. And so what to do?
MOHAMED IMAM: You can always, if you have a fracture, what about the fracture? You can fix it. You can use the base plate screws to stabilize the fracture. You can change your pilot hole into a better bone or a portal, not implantation. Just insert the hemi and revise to a reverse at a later date. And these are the options that you can undertake when you are doing one of these and you have an intraoperative glenoid fracture.
MOHAMED IMAM: For, if you see a patient with a periprosthetic fracture, you can actually follow them,
MOHAMED IMAM: I mean, later on, you can follow the same principles we use and you have to assess. And there's a good thing about shoulders, periprosthetic fractures can be easily managed on operatively, and if needs revision, you can do it with some flesh wires or actually supply sutures, which is a very valid option that we have nowadays. Another problem that we can face is deltoid dysfunction.
MOHAMED IMAM: It can be either because you have undertaken a deltoid detachment or you have an accelerated nerve dysfunction intraoperatively and the risk is not huge and usually it is a fracture. But it is more common with a superior lataral approach. And if it happens, that's a catastrophic complication. And in order to manage it, if you had an axillary nerve injury, there are a lot of complex options that you can undertake.
MOHAMED IMAM: Other less common complications include hematoma formation, which always should make you suspicious of the risk of infection. Other less common complications include thromboembolic complications, and luckily it is less common than what can happen after a hip or knee replacement. So when you are facing this, this is a lot of comprehensive, this is a comprehensive review, I've tried to give all technical bits and you can use accordingly in the exam.
MOHAMED IMAM: But when you are in the exam, remember, you're a day 1 consultant, you don't do procedures you haven't done before. You say principles involve one, two, three. There is a lot of wrong answers, but there is no right one. And common is common when you're talking and whenever you're drawing, if you're drawing shoulder biomechanics or joint reaction force or reverse replacement concepts, I would always recommend draw whenever you can and always keep it simple,
MOHAMED IMAM: simple as much as you do. Thank you very much. Sorry I suppose it was longer than what we've agreed on doing.
DAVID HUGHES: Please don't worry. Muhamad, that was a fantastic talk. So we have a couple of questions. Actually, both of them are sort of centered around sort of lateralization of a humoral component. So Metwally first asks us a question.
MOHAMED IMAM: I've seen it here. As I said, lateralization is better. It is actually not. It it is a newer concept in order to decrease some of the complications with some medialization. But one of the most successful procedure reverse shoulder replacements, is a delta prosthesis and it has a major center of rotation.
MOHAMED IMAM: And let's make medialization in it's original form. And there is actually there was a recent paper comparing components, so between medialization and lateralization, personally I would go for lateralization, but I'm not saying it is better, you know, and also complications can happen with both. Even, I've shown you a slide comparing lateralization on the humeral side and lateralization on the glenoid side and
MOHAMED IMAM: there is even differences between them. So the original components where there is a medialized center of rotation wasn't the best. But then even in the medialized, it is more than that, more lateral than the original design. But I'm not saying medial is better than lateral, or lateral is better than medial, just to understand the concepts in the exam.
MOHAMED IMAM: I had that question in my exam. It was my favorite in I think it was in pathology Viva. And they asked about that. They showed me a Reverse, sorry a rotator cuff of patient to discuss the reverses and they asked me about the concept. I said Grammont principles was one, two, three, four, which I've mentioned here. And then I said, there are concerns.
MOHAMED IMAM: And then we discussed lateralization and I'm sure I nailed it on that station because we went into in-depth discussion. So I passed anyway. But, but it is always good to understand basic concepts and work on them. If you don't fully understand it, just stick to one answer and proceed with it.
DAVID HUGHES: I mean, the key thing is if you can understand why you're doing this even medialization or lateralization when you're doing well, if you're going to a discussion about, which is better - medialization or lateralization, you'll probably doing, hopefully you're doing quite well. And they're trying to gauge the depth of your knowledge.
MOHAMED IMAM: So, yeah, I agree. And there is no right answer. Up until this moment of time, we don't really know for sure. Theoretically possible. Lateralization. Yeah.
DAVID HUGHES: So as Mohamed said, if you can Grammont's principles in terms of utilization, why are we doing a reverse polarity
DAVID HUGHES: shoulder replacement? It's because of cuffupopathy. You're already you're in the past bit and then anything else is window dressing and hopefully you're putting forward evidence as such. So that's a good sign. But as I say, I mean, I'm hoping I wouldn't start saying straight off I'm going to use a lateralized shoulder prostheses at that point. The examiner is going to be thinking hang on.
DAVID HUGHES: What does this person know about lateralization? Then you get into whole sticky wicket about what you don't truly understand. Ok and the other thing I think Metwally wants to know, can you rego over how you lateralize on the humeral side.
MOHAMED IMAM: So humeral component lateralization theoretically improves the biomechanical advantage of the rotator cuff.
MOHAMED IMAM: So it will improve the torque generated by the cuff, if you have cuff or restores the cuff function. So it is actually part of it is done with the component design. So if you want to, use, you use electrolytes, the humeral side, so you can either lateralize the base plate itself, so you put the glenoid sphere on the medial side and you have different offsets for the plastic and then you can lateralize the humeral side, you can lateralize actually with the metal side as well, or with the design of the implant.
MOHAMED IMAM: So you have a center of rotation and the center of rotation is the point at which the rotation of the shoulder happened. So you can lateralize for the glenoid side, as I said, through the metal itself or through putting, for instance, a bone graft which would enable you to achieve the lateralization. But you know, I ran quickly through these slides on humeral lateralization. There are three ways.
MOHAMED IMAM: Either using an eccentric tray or a curved stem, or reduce neck shaft angle or increase increasing the body size. Body sides sorry.
DAVID HUGHES: OK, fine. Is that all right Metwally? Good, good, excellent. Right so also a key thing as well when you're talking about lateralization, if you can throw a bit of basic science in because what you're doing is you're increasing the lever arm of deltoid, which is generally one muscle you can count on in a rotator cuff nephropathy.
DAVID HUGHES: And then you go in a pathology paper. You've got basic science. They'll love that.
MOHAMED IMAM: Yes, and that's why it's important to look at the interaction force diagram, which would be also important to mention or draw here, because you can go through, you know, in the exam, what happens is you say something. And then the last word you say the examiner will pick it up and will ask you another question. So it can start with free body diagram there or can start with the reverse and go to the other side.
DAVID HUGHES: Good right. So I don't think there are any more questions on the chat thing with regards to the lecture. So, we'll obviously we'll call this a quiz later on and have a go but we'll go through this again because there's some very important things in there.
DAVID HUGHES: But if you are going to get a shoulder; the shoulder, they will ask about complications. So if you've got; as with any sort of joint whether knee, hip, shoulder joint replacement, have a little script in your mind about what you would do in the complication situation. OK? And if you've got that prepared, you will be you'll make your life a lot easier in the exam.
DAVID HUGHES: So I know if I know we say you can prepare for basic science, but you can prepare for some of the out of pathology ones because you will know there'll be an infection one, there'll be a complication one again, as well as the trauma as well. OK. So we're going to move on to VIVA's.
Segment:0 .
DAVID HUGHES: Chertsey in Surrey. And today he's going to give us a talk on reverse shoulder replacements and how the complications in dealing with those. It's a really key topic because at the moment we can see that the amount of people requiring reverse shoulder replacement in trauma for example, is increasing.
DAVID HUGHES: So it is a hot topic. So please do pay attention. So without further ado, I will leave you with Mohamed.
MOHAMED IMAM: Thank you, David and thank you, everyone for attending this topic, as David has rightly said. This is actually part two of the talk I gave a few weeks ago on reverse shoulder replacements and now we're going to talk about the complications and how to manage these, especially that now reverse shoulder replacement is a very popular procedure.
MOHAMED IMAM: So, all of you, all of us are involved in it one way or another. And so it is expected it will be coming in the exam more and more and basically, it's a common questionbecause it is a common procedure. What would happen is that you might have Viva stations or basic science stations talking about complications. Some of it might be a bit technical, but I'll just give comprehensive so take whatever you'd like to take and leave the rest.
MOHAMED IMAM: So just a few, the first few slides are just to revive your knowledge about reverses. So we know a key concept describing the mechanics of the normal shoulder relates to the concavity compression, and that's what Matsen et al describes this technique as a ball sitting in the concavity of a table. And so the greater the depth of the concavity, the greater the displacing force needed to dislodge the ball for a given compressive load.
MOHAMED IMAM: And so in the normal shoulder, the rotator cuff muscles provides a compression out of the compressive load, and that subsequently, when lost in rotator cuff deficient shoulders, this will lead to an instability resulting from the unbalanced muscle forces on the glenohumeral joint leading to proximal migration of rotator cuff, then arthroplasty. A second biomechanical point, which was proposed by Madsen and Leavitt as well, is the concept of the glenoid center line.
MOHAMED IMAM: And when you - in a normal glenoid the center present line perpendicular to the articular surface of the glenoid and that actually serves as an important landmark in shoulder biomechanics. When you lose that line, you lose the fulcrum, the deltoid is shortened and that can lead to a lot of problems. And the classic cuff tears obviously can lead to different complications in shoulders.
MOHAMED IMAM: And luckily now, with the advances we're having, we have the option of shoulder reversal, the replacement, which actually serves as a solution for a lot of problems we see. And that's why we are now doing more and more shoulder and reverse shoulder replacements. And if you look at the National Joint registry, you'll find that a huge number of shoulder replacements are being done every year.
MOHAMED IMAM: Actually, it's a number has doubled more than once from 2013 till now. The problem we had with shoulder replacements was the complication rate. And also of all the advances over the years, starting from the first shoulder replacement done by Charles Neer, who many would regard as godfather of shoulder replacements who tried to reproduce a normal shoulder mechanics.
MOHAMED IMAM: Initially, however, the problem was always in rotator cuff deficient shoulders because this was associated with high failure rate and everyone thought about the solution, which is actually achieving a stable center of rotation. And over the years there was important alterations from different designs, mainly influenced by the hip. So very successful hip replacements, however.
MOHAMED IMAM: Basic principles here you couldn't really apply and the problem was always losing the fulcrum and an inability to achieve a stable center of rotation. And the main problem associated with all these designs that was modified over the years was the inability to achieve a stable center and having excessive torque and shear forces at the glenoid component.
MOHAMED IMAM: And it was until this man in 1985 proposed the basic concepts of reverse shoulder replacement by having a medialised center of rotation and distalised center of rotation in the humerus. That decreased the shear forces and create a greater lever arm of the deltoid, putting the deltoid at a biomechanical superior position. And so the patient will be able to achieve a good range of motion
MOHAMED IMAM: ultimately. However, this is without assistance. Obviously you can see how to modify from the first picture on the right, through to the left side by increasing the distalisation of the center of rotation. We now use the reverses for trauma initially, and that's mainly because we realized that it is if in certain cases, if the initial fixation fails
MOHAMED IMAM: of the salvage procedures involving reverse shoulder replacement that this is a paper that we published from Zurich. And so they are associated with drastic complications. And more and more now, because we do more reverses, we are seeing more complications. And also of all the advances we have nowadays with Blueprint and with other custom made implants, we still are seeing more complications.
MOHAMED IMAM: So first, what was the problem with initial designs by Grammont? There was a few complications that was very common, including loosening and launching and stability, which has been reported extensively in the literature, arm length discrepancy and in order to modify and decrease the risk of complications, this guy Frankel from the US proposed having a lateralised center of rotation, either through the glenoid or through the humerus, and you can achieve the either with a metallic augment or a biologic augment.
MOHAMED IMAM: And so either by and that old mainly was aiming to decrease the complications associated with the Grammont design. And this is a by when you say would you use a bone graft to lateralize the center of rotation. There are different tips and tricks you can use on the humeral side as well as the glenoid side to achieve lateral luxation. So what is and that has actually made a lot of systems available to all shoulder surgeons globally with different implants and different concepts but didn't reduce complications
MOHAMED IMAM: and that's what we're going to discuss in the coming few slides. One important thing you have to know is glenoid lateralisation is not the right answer for everything because those patients will have reduced abduction and glenoid loosening while humerus laturalization patients will have reduced abduction as well as the risk of instability. So what are the risks and what are the complications we see nowadays in reverse shoulder replacement and how to manage these?
MOHAMED IMAM: So initial results by Pwllheli have revealed that there is a 15% complication rate in shoulder replacements, and this was published in JBJS America in 2006. But there is a big concern about this paper that 3/4 of the 7,000 total shoulder replacement were performed by surgeons who do less than two shoulder replacements a year. So we know it's not rocket science,
MOHAMED IMAM: we know that if you do less, the risk of you having more complications is high. And so with them, generally speaking, we know that these are the complications that can happen in any replacement we do in the shoulder. For anatomic, the main complications are glenoid loosening and rotator cuff dysfunction, while with Hemi, it's glenoid erosion, as well as rotator cuff dysfunction.
MOHAMED IMAM: But we will focus on rotator on reverse shoulder replacement because we are seeing a lot of this are done nowadays and a lot of these are being revised and presented to us with some of these complications. The commonest complications are notching failures either on the base plate or bone failure on the acromial side, as well as intraoperative glenoid fractures. We'll discuss them in details.
MOHAMED IMAM: We looked at 159 reverses and we reported similar complications in these as well and we're going to go through this in detail. Similar pictures are reported everywhere. Of course, whenever you're doing any replacement, this is a drastic complication you're thinking of. Personally, that's my experience. Either it is a hip, hemi or a reverse shoulder replacement. And so infection was reported to be around 1% of primary total, however, it is up to 5% in a reverse shoulder replacement
MOHAMED IMAM: and that's something you should mention in the exam. And mainly that happened because those patients have large dead space, because you extensive excision, you are undertaken, you have the liberty to take the cuff out, release the capsule, take you can take more bone out. Also, there is absence of living tissue cover, such as the rotator cuff. These patients are usually older population and there is a consensus nowadays among shoulder replacement, amongst sorry shoulder arthroplasty surgeons.
MOHAMED IMAM: Personally, I would think twice if I'm going to offer an anatomic to someone above the age of 75. If I see someone at the age of 80 with intact rotator cuff tendon, I'll be worried that this will fail. So I'll have a low threshold to offer them a primary reverse shoulder replacement. And also it is a viable and very valid vision option so these patients also have multiple previous surgeries.
MOHAMED IMAM: The commonest organism here is still staph aureus, but P acnes is a very common and very popular organism in shoulders. And the problem with infection and shoulder replacements and this is one of the papers you can easily cite. That doesn't come very clear because the majority of patients will have normal white cell count, normal ESR and normal CRP. So 75% plus of these patients will have normal inflammatory markers and will have negative evidence of acute inflammation when you take histological specimens.
MOHAMED IMAM: So this paper is actually a bit of an alert for shoulder surgeons, and that actually would be an indication if you don't have a proven infection, treat it as if it is an infection and you should be a bit more aggressive in shoulders compared with others. We have the same classification for infections here so if you find positive cultures at the time of surgery. I'll do the debridement, find, do the histology, find specific antibiotics and have a close clinical observation.
MOHAMED IMAM: If it is in the first 30 days, I'll go and use their procedure, their approach and many of what we follow in arthroplasty in shoulders is based on what we learn from our colleagues undertaking hips and knees because they have extensive evidence over the years. And so we'll approach that with their approach, surgical debridement and change of insert, if we can. In type III where it is more than 30 days
MOHAMED IMAM: there are two schools here. You can either deal with if it is less than two months similar to type II or proceed with two stage division with antibiotic spacer leaving the antibiotic spacer for two to six months. It depends on a lot of factors and if it is a chronic infection, you can either do oral antibiotics forever or if the patient is medically not fit or do staged revision. And then Christian Gerber who published work on spacers and a two stage revision.
MOHAMED IMAM: And we found that using antibiotic loaded cement spacer is efficient and more than enough for 90% of the patients. And actually, the other thing is that the best function is achieved if the second stage is a reverse shoulder replacement. So, if for example you have someone who had a hemi arthroplasty, which is clearly infected, you have a low suspicion of infection based on the publication we've cited in Journal shoulder and elbow and then you would go for two stage revision.
MOHAMED IMAM: If you leave the spacer in or if you do a second stage hemi, the functional outcomes is significantly less favorable than having a reverse shoulder replacement as a final stage there. An important function that I understand many people don't as important complication that many people do not really understand that much is not showing.
MOHAMED IMAM: And by launching we mean that there is a mechanical impingement between the superomedial aspect of the humeral insert here and the inferior scapular neck, as you can see there, and you can see on the right and why this is important. If you see here, it is also this was very common as well with the medial center of rotations, the original Roman style, because your center of rotation is medial and actually that can cause the notching in the inferior aspect of the glenoid neck here.
MOHAMED IMAM: And why you need to manage this, because there are risks and concerns with notching if it happens because Sirveaux actually graded them as it was there. It is limited to the pillar with grade one, which is usually not a problem. With grade 2 it will be in contact with the lower screw, and grade 3 it is actually over the lower screw and in grade 4 it extends under the base plate.
MOHAMED IMAM: And you don't need to be a shoulder surgeon to tell that great for you will be associated with market loosening of the glenoid. But does it have clinical correlation? That's something you can mention in the exam. Looking at 60 shoulders. There was notching in around 88% in one of the earlier papers looked at Grammont reverse shoulder replacement and that's a huge number if you think 90% of your shoulders will have a notching.
MOHAMED IMAM: So it's not uncommon. And looking at the newer designs, we found that it is actually 35% and actually we found that it doesn't affect scores at five years follow up. But others found that if you have notching and you follow patients for longer periods or periods of time, clinical scores might be affected. And the survivorship of the implant will be affected and Luca Faraud is one of the eminent surgeons in shoulder arthoplasty in France, so notching is a problem, especially on longer follow up, although there is debate.
MOHAMED IMAM: So there are others, there are some who say it doesn't actually influence clinical outcomes and some say it has really it actually has a negative influence. So I think we still need to follow this up for a longer period of periods of time in order to understand the problem. So what is the clinical relevance? As I said, others said it is a predictive value for suboptimal outcome and showing published that it might be an indication for revision in short term.
MOHAMED IMAM: Of course, as everything in orthopedics we need further research. So one thing you can be asked or you should know about if you're interested in shoulders is how to prevent notching. It is if you look at the video, I've shown you earlier, you can do things that would prevent the risk of notching in when you are operating on these patients and doing a shoulder replacement. One option is actually do
MOHAMED IMAM: But to have a sphere position more distal So that you can have less mechanical impingement and you can also increase the arc of movement. And that's a commonly performed technique nowadays. Second trick you can do is by having an inferior tilt of your giving sphere, and that would also increase the arc of motion and decrease impingement. Another op trick you have to mention, or you have to do, is to avoid excessive reaming so that you decrease the risk of idealization of your dreaming and your baseplate.
MOHAMED IMAM: And finally, possibly implant choice might have an effect because we know that lateralised center of rotation and the other technique, like having a bone graft or also what is known as piroarthosy, might decrease the risk of notching as well. So by having how can you have a lateralised center of rotation? One thing you can have a larger glenosphere if you're doing a shoulder replacement.
MOHAMED IMAM: Second option is to decrease the neck shaft angle. Or reduce the cup depth because that will decrease the risk of impingement. Or using an eccentric glenosphere. Or an angled insert which is a proposed trick, but not proven much. So there are different tricks and tips. Maybe not suitable for the exam, but it's worth knowing these steps in order to avoid the risk of notching.
MOHAMED IMAM: If you see a patient with a reverse shoulder replacement that you look at, the inferior scapula angle, assessing, watching and talking about these tricks and tips, which I think would be popular over the coming few exams. Another option, another risk as well, and other complications that we see, we see less in reverses is instability. And with instability, it is common in other implants like anatomic shoulder replacements, which is something you're likely to see in the exam.
MOHAMED IMAM: But I wanted to focus more on reverses here, but just quickly touching on that. A large humeral head can be associated with instability. Other factors include your rotator cuff balance, your subscapularis balance, soft tissue balance, deltoid, function and physiotherapy. Sometimes, if you're doing overzealous physiotherapy, that can cause problems. Is there a problem minister, in reverses?
MOHAMED IMAM: Yes, it is, but it's not as bad. But in some reports, it has been reported to be as high as 30%. So, exam approach like every other thing you answered in the exam as a day one consultant. There are patient related factors, surgical related factors and implant related factors. When you see these or any other joint replacement. What other evidence?
MOHAMED IMAM: The evidence says the chances of having instability after a reverse is higher if the patient is less compliant with poor deltoid function, patients with recurrent falls and prior shoulder surgery. And that's something in clinical or vivus you have to understand before offering a reverse shoulder replacement to one of your patients who is a recurrent faller. I had a patient with a fracture dislocation of the proximal humerus with an admitted patient is a frequent faller demented.
MOHAMED IMAM: I would have a very high threshold to offer a shoulder replacement there. Possibly one option would be supervised neglect because this was. But it's all about patient factors more than anything else. The other factors is surgical factors approach. There is I will talk about approach later on, but you can have other risk factors there related to position of components, which would be applied to any joint replacement humeral lengths discrepancy.
MOHAMED IMAM: Not an important factor here, dead space on having a hematoma. And I think deltoid tension is a crucial point here and also preservation of the soft tissue envelope. So what about the approach? Theoretically, it is said that you can have less instability with supero lateral approach because of preservation of subscapularis. The problem with a simple lateral approach is it's not excised
MOHAMED IMAM: so you can be putting a shoulder replacement in and you have a fracture and then it's very hard to extend the approach through the supero-lateral approach to pectoral. I can open the whole arm through a deltopectoral approach by going lateral to the humerus and as distal as you can. That's another risk. And the other risk as well is maintaining soft tissue balance and approaching the inferior glenoid.
MOHAMED IMAM: So in the exam there is no right answer, but it's worth knowing that. Also, having said that, there is recent evidence saying that there is no difference in stability, in stability, comparing the two approaches together. Surgical factors, so we hate to blame ourselves, but humeral length discrepancy which is important, which can cause a problem, especially if you're doing a revision or in a fracture case
MOHAMED IMAM: and that's why there are a few tips and tricks when you're doing a reverse shoulder replacement for a complex proximal humeral fracture in order to avoid placing the humeral component too low in those with humeral loss. So other aspects as well. Malposition of the components and usually we aim somewhere between 0 to 20 degrees retroversion, which are technical bits you can mention in the exam if you are discussing that deep into your Viva station.
MOHAMED IMAM: It's crucial to preserve the soft tissue envelope, also now there is some surgeons actually not very keen on reattaching the subscapularis Although, personally, I think still soft tissue cover on the components. Deltoid tension, if you increase the lateral offset, you can actually it's crucial to maintain and achieve the deltoid tension right, because the deltoid will be undertaking the function of the deltoid as well as the deficient cuff, which is done when you do a shoulder,
MOHAMED IMAM: reverse shoulder replacement. Other other aspects, which is the design aspects includes the humeral head side and side, sorry and those designs with lateralised center of rotation, some of them, especially if you're lateralising from the humeral side might be associated with instability. And finally, how to manage it? You, as everything else, you have to check, examine and assess the patient in the light of the best interest
MOHAMED IMAM: and then I would obtain plain radiographs and CT scan to make sure I rule out structural abnormalities, especially with base plate fixation failure. You have to identify that and component mal positioning. Remember the slide on the plus key evidence, always, always, always exclude infection. Why? Prevention is always better. It's crucial to assess the stability on table. These are two tests; the shuck test and the lateral thrust test but intraoperatively.
MOHAMED IMAM: This is a nice summary of all tests we use in order to make sure we achieve the right deltoid tension and the right positioning of the component. If you have a positive test in any of these situations, management options would be based on your assessment, especially when you put the trials in. I'm not going to go into the details, but that slide, you can take a look on later on.
MOHAMED IMAM: And then if you have a reverse shoulder replacement coming to you as the day one consultant in the first few weeks after surgery, I would try a close reduction under anesthesia and we have some time and immobilization. If I cannot do that, then you are, this should be done by a shoulder surgeon, obviously, but you have to do removal of soft tissue and feel to clean sphere because it might be causing impingement and causing instability.
MOHAMED IMAM: You can consider using a thicker insert and definitely correction of soft tissue problems like soft tissue abnormalities, humeral length, discrepancy and versions. That's why it's crucial to assess the problem before surgery intraoperatively as well. What, how can you, what you can do for humeral length discrepancy, Here's a bit of the technical aspects here. Well, you have to make sure how to assess how much discrepancy you have
MOHAMED IMAM: and then based on the discrepancy, you can assess and dictate the best treatment option in each of these situations. What about second options of failures here that we saw, a second risk of failures that we cited in our evidence that has been reported on multiple occasions. Baseplate failures. The good news, it is less common nowadays with the newer designs and possibly the commonest aspect and factors that lead to baseplate
MOHAMED IMAM: failure is poor initial fixation and loosening due to osteolysis and infection of course. If it fails, you can have patients with screw failures, patients with growth failure and baseplate failure. And actually the worse situation you can see, which isn't my x-ray, but I took it from Ali Navarni, my colleague, is dissociation of baseplate and glenoid sphere.
MOHAMED IMAM: If also another technical errors that sometimes happens while doing the procedure, is having soft tissue interposition or incomplete removal of the preferred rim of bone on glenoid. Other preventive measures which you mentioned and inferior health and obviously using locking screws, which we orthopedic surgeons are very, very keen on using nowadays.
MOHAMED IMAM: If it fails, I would go for two stage revision, if you're confident, you can go for single stage revision plus or minus the bone grafting. So, what is next? This is becoming more common. We see it in my hospital at least once a month nowadays in shoulders, prevalence is 1.6 to 2.3, and that's based on previous evidence. More and more are actually coming to us nowadays.
MOHAMED IMAM: Contributing factors for periprosthetic fractures, includes elderly population, weak bone quality, osteolysis. If you do excessive reaming of humeral cortex or if you do eccentric placement of the humeral component, and these are all aspects and factors, it's better you should identify as early as you see them. We use the Wright & Cofield classification, which is actually related to the Vancouver one, as you can see on the X-ray or sorry, on the diagram on the right side.
MOHAMED IMAM: With Type A, usually system is stable, with Type B, thus a fracture is centered at the tip of stem with minimum extension and Type C it is distal to the tip of the prosthesis.
MOHAMED IMAM: How to manage it. First, prevention is always better than cure, so when you are doing your procedure, personally, I don't want to use a hand support. Sorry, shoulder support like Kimono or Spider when I'm reaming because that can cause a fracture and it happened to me when I was assisting as a fellow many years ago. Also, you have to be extra cautious and avoid forceful
MOHAMED IMAM: external rotation. It's a reported evidence of having an intraoperatively noise fraction while doing a reverse is actually up to 10% and technical notes here, technical tips here, you have to start restart reaming before coming in contact with the bone. And also you have to be extra cautious when you are reaming osteoporotic bone. And so what to do?
MOHAMED IMAM: You can always, if you have a fracture, what about the fracture? You can fix it. You can use the base plate screws to stabilize the fracture. You can change your pilot hole into a better bone or a portal, not implantation. Just insert the hemi and revise to a reverse at a later date. And these are the options that you can undertake when you are doing one of these and you have an intraoperative glenoid fracture.
MOHAMED IMAM: For, if you see a patient with a periprosthetic fracture, you can actually follow them,
MOHAMED IMAM: I mean, later on, you can follow the same principles we use and you have to assess. And there's a good thing about shoulders, periprosthetic fractures can be easily managed on operatively, and if needs revision, you can do it with some flesh wires or actually supply sutures, which is a very valid option that we have nowadays. Another problem that we can face is deltoid dysfunction.
MOHAMED IMAM: It can be either because you have undertaken a deltoid detachment or you have an accelerated nerve dysfunction intraoperatively and the risk is not huge and usually it is a fracture. But it is more common with a superior lataral approach. And if it happens, that's a catastrophic complication. And in order to manage it, if you had an axillary nerve injury, there are a lot of complex options that you can undertake.
MOHAMED IMAM: Other less common complications include hematoma formation, which always should make you suspicious of the risk of infection. Other less common complications include thromboembolic complications, and luckily it is less common than what can happen after a hip or knee replacement. So when you are facing this, this is a lot of comprehensive, this is a comprehensive review, I've tried to give all technical bits and you can use accordingly in the exam.
MOHAMED IMAM: But when you are in the exam, remember, you're a day 1 consultant, you don't do procedures you haven't done before. You say principles involve one, two, three. There is a lot of wrong answers, but there is no right one. And common is common when you're talking and whenever you're drawing, if you're drawing shoulder biomechanics or joint reaction force or reverse replacement concepts, I would always recommend draw whenever you can and always keep it simple,
MOHAMED IMAM: simple as much as you do. Thank you very much. Sorry I suppose it was longer than what we've agreed on doing.
DAVID HUGHES: Please don't worry. Muhamad, that was a fantastic talk. So we have a couple of questions. Actually, both of them are sort of centered around sort of lateralization of a humoral component. So Metwally first asks us a question.
MOHAMED IMAM: I've seen it here. As I said, lateralization is better. It is actually not. It it is a newer concept in order to decrease some of the complications with some medialization. But one of the most successful procedure reverse shoulder replacements, is a delta prosthesis and it has a major center of rotation.
MOHAMED IMAM: And let's make medialization in it's original form. And there is actually there was a recent paper comparing components, so between medialization and lateralization, personally I would go for lateralization, but I'm not saying it is better, you know, and also complications can happen with both. Even, I've shown you a slide comparing lateralization on the humeral side and lateralization on the glenoid side and
MOHAMED IMAM: there is even differences between them. So the original components where there is a medialized center of rotation wasn't the best. But then even in the medialized, it is more than that, more lateral than the original design. But I'm not saying medial is better than lateral, or lateral is better than medial, just to understand the concepts in the exam.
MOHAMED IMAM: I had that question in my exam. It was my favorite in I think it was in pathology Viva. And they asked about that. They showed me a Reverse, sorry a rotator cuff of patient to discuss the reverses and they asked me about the concept. I said Grammont principles was one, two, three, four, which I've mentioned here. And then I said, there are concerns.
MOHAMED IMAM: And then we discussed lateralization and I'm sure I nailed it on that station because we went into in-depth discussion. So I passed anyway. But, but it is always good to understand basic concepts and work on them. If you don't fully understand it, just stick to one answer and proceed with it.
DAVID HUGHES: I mean, the key thing is if you can understand why you're doing this even medialization or lateralization when you're doing well, if you're going to a discussion about, which is better - medialization or lateralization, you'll probably doing, hopefully you're doing quite well. And they're trying to gauge the depth of your knowledge.
MOHAMED IMAM: So, yeah, I agree. And there is no right answer. Up until this moment of time, we don't really know for sure. Theoretically possible. Lateralization. Yeah.
DAVID HUGHES: So as Mohamed said, if you can Grammont's principles in terms of utilization, why are we doing a reverse polarity
DAVID HUGHES: shoulder replacement? It's because of cuffupopathy. You're already you're in the past bit and then anything else is window dressing and hopefully you're putting forward evidence as such. So that's a good sign. But as I say, I mean, I'm hoping I wouldn't start saying straight off I'm going to use a lateralized shoulder prostheses at that point. The examiner is going to be thinking hang on.
DAVID HUGHES: What does this person know about lateralization? Then you get into whole sticky wicket about what you don't truly understand. Ok and the other thing I think Metwally wants to know, can you rego over how you lateralize on the humeral side.
MOHAMED IMAM: So humeral component lateralization theoretically improves the biomechanical advantage of the rotator cuff.
MOHAMED IMAM: So it will improve the torque generated by the cuff, if you have cuff or restores the cuff function. So it is actually part of it is done with the component design. So if you want to, use, you use electrolytes, the humeral side, so you can either lateralize the base plate itself, so you put the glenoid sphere on the medial side and you have different offsets for the plastic and then you can lateralize the humeral side, you can lateralize actually with the metal side as well, or with the design of the implant.
MOHAMED IMAM: So you have a center of rotation and the center of rotation is the point at which the rotation of the shoulder happened. So you can lateralize for the glenoid side, as I said, through the metal itself or through putting, for instance, a bone graft which would enable you to achieve the lateralization. But you know, I ran quickly through these slides on humeral lateralization. There are three ways.
MOHAMED IMAM: Either using an eccentric tray or a curved stem, or reduce neck shaft angle or increase increasing the body size. Body sides sorry.
DAVID HUGHES: OK, fine. Is that all right Metwally? Good, good, excellent. Right so also a key thing as well when you're talking about lateralization, if you can throw a bit of basic science in because what you're doing is you're increasing the lever arm of deltoid, which is generally one muscle you can count on in a rotator cuff nephropathy.
DAVID HUGHES: And then you go in a pathology paper. You've got basic science. They'll love that.
MOHAMED IMAM: Yes, and that's why it's important to look at the interaction force diagram, which would be also important to mention or draw here, because you can go through, you know, in the exam, what happens is you say something. And then the last word you say the examiner will pick it up and will ask you another question. So it can start with free body diagram there or can start with the reverse and go to the other side.
DAVID HUGHES: Good right. So I don't think there are any more questions on the chat thing with regards to the lecture. So, we'll obviously we'll call this a quiz later on and have a go but we'll go through this again because there's some very important things in there.
DAVID HUGHES: But if you are going to get a shoulder; the shoulder, they will ask about complications. So if you've got; as with any sort of joint whether knee, hip, shoulder joint replacement, have a little script in your mind about what you would do in the complication situation. OK? And if you've got that prepared, you will be you'll make your life a lot easier in the exam.
DAVID HUGHES: So I know if I know we say you can prepare for basic science, but you can prepare for some of the out of pathology ones because you will know there'll be an infection one, there'll be a complication one again, as well as the trauma as well. OK. So we're going to move on to VIVA's.
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The cadmore media player is a professional video and audio player experience designed to deliver media as well as relevant transcript, segmentation, and metadata. On the screen is a traditional html video player with buttons such as play, pause, forward, captioning, language and play speed selection and more. Adjacent to the video player are generally tabs, one of which shows a scrolling transcript of the video and the other shows any segmentation of the media, sometimes referred to as chapters. At the top of the video is a menu bar containing an Explore button and Tools button. The Explore button allows you to dig deeper into the video by opening up an explore dialog which contains tabs for a visual navigation of the video using thumbnails, an about tab which contains rich metadata about the media, a segments tab which contains further information about the video, and a related tab which contains links to other media related to this media. The tools button opens a menu with options for sharing the media on social media, creating bookmarking links, creating embed codes for your website, generating citations, and more.
Keyboard Shortcuts
Keyboard shortcuts only work while you are in forms mode. By entering forms mode, you will be able to quickly access portions of the media player with single key commands.
Spacebar: Play/Pause Toggle
I: Info Menu,
O: Tools Menu
T: Transcript Tab,
S: Segments Tab
F: Forward 15,
R: Rewind 15
L: Languages,
P: Playspeed
M: Mute Toggle,
V: Volume Bar
N: Video Only Toggle,
B: Full Screen Toggle
C: Captions Toggle
Escape: Closes dialogs and menus / Exits Player
Z: Next Transcript Chapter
X: Previous Transcript Chapter
Q: Next Transcript Paragraph
W: Previous Transcript Paragraph
Entire Media
Segment(s)
Custom Clip
Start At:
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Embed Size
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You Size - Responsive
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We Size - Responsive
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Picture Overlay Popup
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400 x 225
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512 x 288
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400 x 700
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768 x 1024
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1024 x 512
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1280 x 608
Form Title Cite
No citation provided.
Info
Segments
Related
Thumbnails
Exit Clip Mode
You have requested to see a portion of the video outside of the clip.
Click OK to switch to the full video or click if you would like to stay inside the clip. You can always go back to the clip with Tools and Clip Mode