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Online FRCS Course - Basic Sciences for Orthopaedic FRCS Exams (1)
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Online FRCS Course - Basic Sciences for Orthopaedic FRCS Exams (1)
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Segment:0 .
If I got one for you, here we go to particular next week as well, isn't it?
Yeah Yes. Yeah thank you. All right. So we've got a 50-year-old male. He's been in a road traffic collagen. We've done Atlas. These are his scans. Let's say we're going to take him to theater. All right.
Everything else is done. Anaesthetist ICU. We've decided that we're going to take him to theater and we're going to reduce this and fix it with an CDF. OK, so tell me about your approach. OK, so I'll divide my management in the theaters, I will divide it into clusters of patient positioning because this is bilateral dislocation, so I will be very careful with the patient positioning.
So there will be in terms of positioning, I will put a sandbag under the scapula. The head end up by 30 degrees, neck extended, rotated to the other side. So I prefer doing it from the right side to the. The head would be slightly rotated to the other side, making sure that there is no increase. There is no neurovascular deficit. And if there, I will be very careful.
If there is any neurovascular deficit, I will be stopping it there and then I will position the image intensifier checking, making, doing a level check. My incision will be a transverse incision at the level of the. Six seven cervical vertebra of the extent would be from the midline to the left to the bottom of the standard mastoid skin, subcutaneous tissue and the investing layer of the cervical fascia is the first layer along with I will like it the external jugular vein, which comes laterally.
Following this, my plane of dissection would be on the lateral side. It will be the carotid sheath, including the carotid vessels, the vagus nerve and the internal jugular vein. On the lateral side, it will be the standard thread and the strand hard muscle. Following this doing this at this time, I will get the superior and the inferior arteries, which will come in the field.
Following this, I will have the so that sort of Standard Chartered and how it goes along with the pre tracheal fascia. Next, I will encounter the esophagus, the esophagus and the trachea dissected immediately. Following that, I will have the prevertebral fascia I will inside the pre-verbal fascia, making sure that the longest kaleigh muscle, along with the sympathetic trunk, are taken off from the bone and dissected laterally.
And I will come onto the vertebral onto the entire surface of the vertebra. I will reduce. I will first. I will do that to me. I will. And then followed by a reduction. If the reduction is achievable, then I will fix it with a cage and and plate.
If the reduction is not achievable, then I might have to consider a fuel reduction maneuver, which involves hyperextension. If not, then I have to preliminary I will fix it entirely. Temporary fixation to make the patient prone and remove any block in reduction was clearly fixed positively. Then again, come back in a position and do the definitive fixation in the anterior position.
OK, that's good. Pretty definitely a high pass from me. I don't think I hide anything else. I agree with your positioning. Yeah you said you were going to go on the right side, it doesn't matter which side you go on. I tend to go on the left.
Just because of the recurrent right? The recurrent laryngeal nerve. But it doesn't matter provided, you know, provided you have a reason why you're going one way or the other. So these are landmarks. So your mandible is key to your hyoid C3, your thyroid cartilage is C4 C5, you're quite C6, which is where you were going to go.
And then see 6 to 1 is down here. Do we need to mention this in the approach. Or is it OK to just? And I think in that one way you can say, I think it was C five, wasn't it? So I think you can say, look, my landmarks would be the cry coin at C six, because that's going to be the most palpable.
And probably the thyroid cartilage for that one, if you're going to go higher, then you should probably mention the hyoid. But then the I mean, you said you were going to check with I would probably double check with when you get down to stripping off the longest collie as well. So you talked about superficial fascia, but is my external jugular vein.
It's around the neck splits around CUCM and trapezius. The tracheal fascia, which is continuous with the carotid sheath, your superior inferior thyroid vessels run from the sheath to the midline, and they kind of the only structures that are passing medial to lateral when you see them in your approach. And in some ways, they do restrict your access, but you can locate them prevertebral fascia.
And of course, the sympathetic trunk runs on its surface, with the stellate postganglionic little bit lower down. So this is the diagram that you need to know. And so it just describes so it shows here how we've got the strap muscles, the thyroid. Trachea and esophagus. Retracted one way, and then we've got the carotid sheath and the stern applied a mastoid the other way so that we can come down onto the preferred crusher, which overloads the longest collie muscles and the anterior longitudinal ligament.
All right. So this is the diagram that you need to remember in your head when you get asked about this approach. OK and what else? Michael, for this one? Yes, so this is a technique and you basically talked through this and this is what you need to say. So the thing is you can do a transverse incision you got, but it kills me because it's within the line of the fibers.
But if you need to do multiple levels like, say, you've got a myeloma or something with multiple vertebrae you need to fuse, then you're going to have to go with a longitudinal incision. The multiple levels you split the plasma in the line of its fibers with your finger. think you said that identify the anterior border of ECM and inside the fracture longitudinally. Take it laterally.
Retract the strap muscles. The trachea and the esophagus immediately expose the carotid sheath. And this is the bit that I got grilled on in one of my exams, actually this part of this approach. So you want to develop this plain, that's why I put a bit more detail. You want to develop the plane between the carotid sheath and midline structures.
So that you can retract the sheath laterally with the stent, Clyde and mastoid to take it that way, like in the diagram. Oh, can I just quickly ask one thing? I mean, this critical fascia and the carotid sheath are continuous, I think. Yeah, Yep. So you need to size them, ok? And political pressure comes medially, and the carotid sheath with its content goes lightly.
That's the point that I got asked a lot in my exam. Um, exactly what I was going to do with the carotid sheath. So it's what it says. Superior inferior thyroid arteries that the medial collateral and then you basically need to work immediately. And go gently because you're going behind the esophagus. And then, as you said, down onto the prevertebral fascia in the midline.
Make sure you stick in the midline because you've got the sympathetic chain over the longest collar on each side. You split it longitudinally on the anterior longitudinal ligament and then you dissect it so periodically. And this is the only thing I would do different particular. I'm sure you do. It is when you get down to the actual vertebrae, I would probably put a needle in the disk and just check my level.
That's the only thing I'd do differently. Dangers, recurrent laryngeal nerve, so the injury rate reported in auto bullets is 2.3 percent, and there's no difference between the right side and the left side, which I think is why we say it doesn't matter which side you go on the right side. The recurrent laryngeal nerve is a little bit more variable and runs a little bit more of an anterolateral course and on the opposite side.
So it's slightly more vulnerable, which is why I go on the left on the left side. The recurrent radial nerve is slightly more protective, but you've got the thoracic duct on the left side. And so that's know, it's your choice, whichever one you want to go. But there's a risk to everything on it. You know, there's a risk with everything we do. So that she recurrent laryngeal nerve, the rusike duct C7 T1 sympathetic chain, Horner syndrome, the carotid sheath.
Any of these big red blue things is going to be bad. All right. Vertebral artery, inferior thyroid artery. And the other thing that you can mention is that if they develop a post-operative retropharyngeal hematoma, you need to decompress them because they can get OA compression. All right. That's it for this Ms Robinson approach.
Any questions is made up of a femoral device, and that's typekit a device on the femoral side that's composed of a stem. And that stem has a part that's in the data. The metathesis that has a neck with a trillion and then articulates with a ball. That ball is typically made of metal or ceramic. On the acetabular side, you have. Fantastic so obviously, we've got lots of surfaces here.
Tell me how they interact with each other. The surfaces of this looks like an unscented device. The surface is therefore based on friction and a press fit that interacts directly with the bone that can either be partially coated or uncoated, depending on the hydroxide hydroxide appetite, which will encourage in growth austere, conductive and on the interaction between the onion and the ball. That's again, a friction talk surface, usually the trinian's differential shape that can be based on the difference between the proximity of the engine and the ratio to the distal end that articulates on the inside with again a friction fit with the inside of the metal head, which is, you know, symmetrically shaped.
When we talk about interactions, we we're talking about typology. Now what is true symbology is such typology is the study of how materials interact with each other through friction. Is it just friction? It's through fiction, and I guess it's a study of how surfaces interact with each other in motion that includes friction and lubrication.
And so we know that what's more important for us is orthopedic surgeons. Lubrication and how much where there is at the implant interface, what is where then where is the loss of material due to motion? Is it just that or are there other ways of how it can happen? Where can either be chemical or mechanical? And I can talk through those types of wear.
So tell me about mechanical. Mechanical can be divided into abrasive adhesive and subsurface de lamination. Abrasive wear is when there's different types of wear there, when there's disparities which interact with each other and break off parts of the material. And that can be due to four types of where I can talk through those. Alternatively, yep, first point you wear is when to implant interfaces that are designed to interact wear out.
Second body is with an implant that intended on one surface were not intended on the other side. Third, body wear is when you have a loose body, for example, between two surfaces that are interacting and fourth body wear is when two non intended surfaces are interacting. OK, so tell me in terms of your experience, how has this affected your work? Where is affected, my work, particularly related to hip replacement in terms of reasons for revision.
For example, when we're choosing implants, we want implants that have low wear and high fatigue strength, low fracture risk as well and implants that are working under their endurance limit. So, for example, my preference is to use in active patients a cemented a ceramic on poly interface. That's because that's designed to have low where ceramic is as low friction and highly cross polyethylene has extremely low wear, with some compromise with fatigue and endurance.
OK all right, I think that's probably exhausted that one. It can be quite a dry topic, to be honest, where so dry theology, as I say so. So I'm part of that structure. So how do you think you went with that, kartik? I took some. I was trying to work out where to go with it. I think I knew the answers. It's just I was probably I need some advice as to how to get on with it.
Yeah so it can be quite difficult one in terms of they'll probably lead you along in some of the best, some of the basic science ones. What I would suggest is try and preempt them. So if they're so, they'll give you a little clue. So anatomy of an anatomy of a hip replacement? They will talk. They'll want to talk about the interaction between the different surfaces there.
Yes, I gave you on some medicine one. But normally you'll get a cemented one because I also want to know about the interaction between cement, the cement and metal interface as well. So there are all these different surfaces that they want you to go through. But actually, from overall, you were very good. You knew the answers you had. You did a little bit of prompting to get some things across, but that's fine.
Minimal prompting is all right. So from my point of view, we're very safe past, but obviously we're trying to Polish it up. So yes, technology, the science that deals with the interaction between surfaces such as and motion and the consequences of that interaction. They do like their definitions, so try and be a little bit more Precice with your definitions and where progressive loss of a bearing surface as a result of mechanical, of mechanical or chemical wear.
Now, mechanical wear can even be removed material from surface by mechanical action. So brace it at ease of fatigue and electrochemical. I don't want to go too much on that. I'll come later. So galvanic fretting, pitting corrosion. But the examiners will push you on to get everything. But I was very pleased you talked about a brace as well. He said, well, if fatigue won't discuss a bit later as well.
Then also in terms of moans of wear in the joint off, see how it can be done. You've talked about motion, the primary between two bearing surfaces, the expected motion between varying surfaces with a secondary non bearing surface, a head rubbing against the back liner. So try and involve a bit more experiences in terms of clinical application of it. So basic science.
They sometimes they want you to go. It can be a very dry topic. They want you to move on, sometimes onto the more sort of clinical side. So if you can apply the basic science scenario in a clinical scenario, that's what they want. That's push you towards a 7 and 8 and 2 and then obviously third body where stand in the shoes, for example, or two non bearing surfaces really get together trying it in the head.
Again, that's a big thing at the moment, and particularly for varsity. So if you can push some of that in, that's a good example of your understanding that you've got this good core basic knowledge and you're applying it in the clinical situation that way that's push you from at six, hopefully towards a 7 and an eight. OK does that make sense?
Got it. Absolutely thank you. There's any questions you like to ask. You no, again, it's just I was trying to give the examiners and you some points and I was hoping you just tell me, ok? Talk more about that. Otherwise, I'd have gone 10 minutes into chemical and gale galvanic corrosion, getting any points.
So is that appropriate to stop offer and then back off and then wait. Yes as I say, sometimes it will happen. If there's a gap, don't make it to on a gap. They will want that. They may want you to move on. But yes, I was happy you stopped because I wanted to move on to different topics such as the subject. If you're carrying on, don't worry the main problem.
That's great. That's fantastic. Can I just ask you about this or what can I pick up on? I pick you up on this. It's not necessarily then prompting you. Is this then there? I was happy with your answer, and I was trying to move you to get you to score more points. So the anatomy of describing a hip replacement, that's the starter opposite.
That's the relaxed, warm you up because everyone knows what hip replacement is. Hopefully not. You're in the wrong exam. But as I say, that's as I say, they always have a relaxing question and then to warm you up and then they'll push you onto the meat of it was a good understanding of where was and also good understanding of the different modes of where, as I say, the way how you can now improve that answer is applying it in that clinical scenario.
So that you can show and demonstrate that you are fit because we all supposedly have learnt this as part of our first years of being an orthopedic registrar, but it's how we apply it as an orthopedic surgeon. Yeah, in terms of did it quite well. When you're talking about the type of implants you talk, you want to pick up on as a hip surgeon, for example. OK, thank you. And that sometimes could be another question.
All right. So we'll move on to the next five minutes. So how each of these images created? What do you see here on the right? Start with the top one. As at the top one is a kernel image of the knee joint is the MRI scan of T2 weighted because the fluid looks bright. OK, so what's the MRI scan?
What's one of those so MRI stands for is a magnetic resonance imaging, which uses a superconducting magnets and radio frequency impulse to create an image. So this uses the principle of each atoms in our body as part of the hydrogen atoms. So which is responsible for these images? So fluid, the tissues, which consist of hydrogen atoms, each responds to these magnets.
And so when the tissue is placed under the magnets, what happens is the so before that the atom has got two functions. One is its spin along its axis, and the other function is as a politician. So when it spins, it also wobbles. So when the tissue is placed under the water standard, the atoms becomes a longitudinally aligned. And once the radiofrequency impulse is given, it is transversely placed on the time taken from the transverse alignment of the long alignment.
About 6% to 7% is 2 to one, and then the remaining is T2. And based on that, we will get it to you and waited and waited images. And again in T1 weighted images on the TR is a repetition sequence is both the repetition sequence and the echo sequence are shorter and then the both are longer in T2 weighted images. And also we got two different sequences is called the superior consequence and is the most commonly used.
And also there is a metal artifact reduction sequence, which is used in metal and metal. Yeah so and again, there are some potential advantages and disadvantages at the point of just being no radiation, no ionizing radiation risk. But the disadvantages is claustrophobic. Again, yeah, OK. So if we move on, what about the second image? What's that?
This is in a city currently. Image again. So the so again, the CT scan is an imaging modality, uses a radiation. So it's basically it uses a multiple X-ray sources and it is again, it has got a detector on the other side. So it's kind of a limited the X-ray source and then the detectors also receive another direction.
So instead of patient moving, it's they say here, it just circles around the patient and then we get a 3D picture. So that's the difference between the X-ray and then the CT scan is the multiple X-ray sources has been used here and then the and also the soft tissue and then the bony delineation is better in the CT scan. So soft tissue to use, so does not use to delineate.
Sorry, I meant that the CDC has not meant for a soft tissue details. However, when compared to the X-ray because the X-ray and say the X-ray images are produced based on a high beam, low beam attenuation. But here the CT scan will give a good delineation of bony details, and that nicely separates from the soft tissue details. OK, so you briefly mentioned attenuation.
What? what do you understand about that? And so the different, different tissues in our body, it's a differentially absorbed and the high energy electromagnetic radiation. So based on that, we will get the images. So the high beam attenuation means is there is an absorption is high and the low beam attenuation means its absorption is low. OK, where is it measured using any units?
And it is measured, and I think it's a millisieverts. so about the two, it's innovation, not the amount of radiation. Oh, sorry. So I'm not sure about the problem. That's right. And so, yeah, when would you use a CT scan? When would you typically order a CT scan?
What kind of clinical situations? Yeah, I'd say the CT scan is useful to delineate any particular fractures and then to and also this provides a three dimensional picture instead of two dimensional pictures and x-rays on the preoperative planning to. I think that's the time it time's up. It's five minutes is up. Good good, good.
Yeah, I think I think it started well with MRI scan. Probably the CT scan a little bit a stumble. Not the ivory did very well. Yeah, it's one of those is that, you know, you kind of learn it once upon a time and then you've got so much to learn. It kind of goes at the back. But but it's useful just to keep refreshing that.
So your MRI, you know, you mentioned everything. Can you hear me? Yeah, yeah, I can hear. So I just got a message. My internet is unstable, so I'll just make sure you cut out. OK? so, Yeah. MRI is good, too. You mentioned the very thing that once you do mention about, you spoke about the strong magnetic fields and the radiofrequency to close.
So you've got your atom spinning and then when you they line up with longitudinally, don't they? Then you apply radiofrequency pulse and they transversely which, which is what you mentioned in their possession also all lines up at the same time. And they mentioned about the T1 and T2. That's good. So yeah, it was the T one is the relaxation time, isn't it?
The two hour time is from when it goes from longitudinal organization to the recover 63% You mentioned 60 seven, so 63% of the normal once the radiofrequency is stopped and. T1 is good for anatomy, isn't it? It's good to show you anatomy data for pathologists. Yeah, teachers, for pathology, isn't it? So and that's the time from the transverse when the transverse magnetization vector decays by 37% know.
So it's 60 three, 30 seven, 30 seven, so, yeah, good you mentioned about the image that you saw the water's dark on to 1/2 is brighter and you're aware of the fact suppression. I think you mentioned the stir sequences and the Mars sequences, where the metal artifact reduction sequence, which which was good. Also throw in there the use of contrast, which is good to enhance the damage to tissue T1 way to insert something extra to throw in, which is very, very good.
So Uh, Yeah. MRI, so, you know, always, always useful to know about usage advantages and disadvantages. It sounds very basic, but it's always important to make sure you know, and obviously, as we know, it's good for soft tissues or cold fractures. Malignancy doesn't have any ionizing radiation like axilo, but is expensive, can be claustrophobic for patients. And obviously, you've got some precautions many pacemakers, ICDs and cardiac and brain, et cetera.
And cochlear implants something to the disadvantage about CTE. Again, I thought you did well, actually. You know, I think the only thing you need to really know about is the hinesville field unit has four units of attenuation. So just that water zero and then you've got bone is 1,000 and then there's minus 1,000. So you know, the water's in the middle between air and bone and that's the, you know, the marker of attenuation.
So you knew about that. You're able to describe how the modern CT scanners have developed. You've got the helical spiral ct, as well as it rotating the Gantry. You've also got the actual where the patient, the couch for the patient. Also moves. So it's not just a Gantry moves, but they're both moved together, so it speeds up even more now.
The it's also useful to throw in, because how is that different to an X ray? Well, you've got pixels and voxels, so you know, each so two days a pixel. But then when you've got a volume of tissue, the depth that becomes a vauxhall's, that's by definition, you know? So from the actual images, it then creates.
A 3D image and that each one of those volume of pixels called a Voxel. So these are little terms. So fan shaped X-ray beam tissue attenuation coefficient kaleena detectors pixels voxels. These little terms to throw in and obviously this advantage is know, it's radiation, isn't it? So that's the disadvantage.
So you've got to make sure you use it appropriately. But it's got massive advantages like predictive planning for nonunion unions, deformities, complex fractures, intra articular fractures, rings all the time debris. And then it's also useful to know about, you know, registered images with PET scans and things like that as well. That's good. I think that's five minutes of feedback. So what do you see here on the right?
So it's a plain radiograph showing a major fracture of the fema, which has been treated with an intermediary nail. OK, so intermediary nail is a load sharing, device sharing device. A not necessarily can you can't put compression across it in case of a hind foot nail. So if it's not a load sharing device, what is it load bearing?
So, so when might be a load bearing device? I'm like, like a total knee replacement with as a nail when using a nail. Like, if you have a comminuted area and you want to maintain the length or will become a more of a load bearing, isn't it, rather than load bearing in this situation?
The whole concept is applied here. So in this situation, the concept is load sharing. Yeah so there is bone to bone contact at the fracture site. OK so, yeah, good. What do you understand about working length of a nail? So the working length of a nail is the nail, which the part of the nail, which is free from being in contact with any surfaces.
So for example, in this case, the screw at the bottom and the press fit at the fracture, at the estimates is the working length, the distal end and then the proximal end is from the other screw to the or even the metal facial area where it's attached to the fracture site. OK so when you ream the femur.
You have a really tight fitting. Dale, Yeah. Where's the working leg there? So in the tight fitting nail you? It's from the screw, from the locking screw to the area of the instrument. So where was what from the distal screw, from the proximal screw to the estimates and instruments to the distal screw so that they'll be the working land where you feel?
So the area, the area of contact with the bone could be more than just a point. So the surface area where it is touched from the distal end of that surface area to the locking screw of the bottom? OK, we'll come back onto that, but just one more thing. So do you solid or hollow nails and what's the difference between them? So I use a hollow nail.
The difference is that the strength of the material is stronger with the same diameter nail for the same material. But the flexibility of the nail is reduced when you use a solid nail, so the risk of breakage is higher. And also in ease of insertion is better with a hollow nail.
There is also the moment of inertia is also better with hollow nail because the difference between the inner and outer diameter nail, which which helps. But OK, if I can just stop you there for a second. So but obviously, a more solid nail at the same time, it is a hollow nail. Surely this so there will be stiffer than hollow now.
Yes, it's solid. Yeah, that's true. So the solid nail is more stiffer, and therefore it's more there's the elasticity of the nail is reduced compared to bone. So therefore there's a mismatch of the elasticity between the bone and the nail is higher with the solid nail. So a hollow nail would give you a bit more flexibility, relative flexibility.
OK you mentioned about. So I think that's five minutes up, isn't it? OK right? Just move on, go through things. How do you think that went? I don't know if I was clear with the working men, actually. OK, fine. Welcome up.
Welcome on to that. Yeah so. Axilo sharing a load bearing. It depends on what you're doing, isn't it, so. You know, to just kind be clear about that and don't get to. Fixed with our nail has to be load sharing, but it depends if you've got a significantly smashed up FEMA. And you're bridging it with a nail.
Well, it's not quite bearing, isn't it, anymore, you know, sharing. So it's, you know, it's going to be bearing more, isn't it? Yeah so, you know, you just have to be careful. It's not. It's a concept, not as kind of, you know. It's not a device, its concept, isn't it, of what's happening mechanically, so that's one. The second thing with the working length.
I think so. If you've got no Islamist contact, then the working length fair enough, is between the two screws. Yeah, but if you've got. A lot of contact in this miss. You've renamed you put a big nail in the biggest. You can then the working length is the contact area there nothing to do with the screws?
Oh, OK. OK so that is your working life. And so. That's important to just bear in mind with the work length of a nail. So that's why you want as much contact in this one, you put a bigger nail just stiffer, you know, to. You've got as much contact, bony contact as possible as well.
Is that is that clear? Yeah so in a dream now when you remake the tightest, most like in this case, you can say, actually the working length is quite short and it's within the isthmus because it seems to be a good amount of contact. Yes, for example, an elderly patient that, you know, they're proximal femur, if they've got a reverse oblique microfracture or whatever they might have and you nail it.
They have quite capacious canal, don't they? Um, and the working length in that situation is between the hip screw and the distal locking screws, isn't it? Right that's the. That would be working in that situation. Then this one is slightly different. Right, carry on to the next thing about sölden Holland. What do you think this was sort of probing about?
What do you think this sort of was trying to tease out of you? Is the difference between a hollow nail with the two diameters and the solid nail with a single diameter? It's talking more about this sort of second moment of inertia, isn't it? Yeah um, and understanding that together with Poland moment of inertia as well. Now The when denial is the whole point is it's like bone, isn't it?
The whole point is the second moment of inertia measures the cross sectional distribution of material from the center. OK, so it's the amount of material outwards. And so you think, well, OK, there's not much material in the middle. It should be less stiff, et cetera. Should have less bending stiffness and torsional stiffness, but actually with the same material.
Because you've distributed it further away. It's better than a solid network, because in the middle, that material doesn't have much resistance to bending or torsion. OK and that's and that happens in biology, doesn't it, as we get older, our bones. Become more hollow and make a bigger, more load is distributed further to try and compensate for the structural deficiencies as we age to try and give us a stiffer bone.
And that's what happens. OK, so so this is talking about second moment of inertia, which, for a hollow nail, a solid now. I've not put the equations here, but it's pie art to the fore, isn't it? Which which is. Different for Holland now, because you need to subtract the radius of the outer circle in the inner. And, you know, to be absolutely accurate about the actual second moment of inertia of a hollow a solid now.
So the second wave of inertia is it's also known as every moment of inertia. And that's. Regarding bending stiffness, but you've also got polar moment of inertia, which is talks about the torsional stiffness of the nail, so that's all about the, you know, the torsion rather than the bending. So they're both their forces, but in different planes, aren't they so?
It's just important to understand those principles, because that's what I'll be getting at and trying to come at you from a different angle, just trying to see whether you understand the differences between the two types and those two. Principles, moment, inertia and the second momentum. Well, Yeah. Thank you. Is that clear, so I think I think you just need to revise that a little bit and just horrify that bit in your head because it's easily confused when you sort of.
Here to battle in an exam. Yeah was that right? Yeah, thank you. OK right. So I think I've got a good game, there's one question if you don't mind just critical thinking to make a comment. Yeah, I'm actually a bit confused about the working lens, so I know that the working length is the length of unsupported bone.
But if you rim and then you provide a nail with good aesthetic fit, you mentioned that the working length is therefore the length has got aesthetic fit. If you have a better fit nail, wouldn't there be more bone contact and therefore a bigger working length by the definition? So your area of contact is where is that really going to be? It's not going to be proximally or distally in the metathesis.
It's going to be because that's the tightest part of the femur, isn't it? You know, whenever we look to nail a bone, we always look at the isthmus. How tight is that going to be? Am I going to put nail down there because that's going to be the tightest bit. So really, that's going to be where your contact area is. You reduce the definition change.
It goes from working length is the length of unsupported bone to suddenly the working length being the length of supported or contact bone. So so your working length in the where there's no there's no contact is between the two areas of support, which is the two screws either end. Yeah and. Because I think is it ramachandra, some of the kind of, you know, they just talk about that, but in the nail.
Unlike in a plate and a plate, it's quite straightforward. It's just between the two, you know, screws either end of the fracture site is the working length. But in the nail, you also have the contact within the space. So it because that's going to be, you know, that's going to be taking some of the support in the actual area of contact in Midland Bowen. It's my show.
So therefore, the working length is the area between unsupported bone minus the area of the ethnic fit and therefore you've reduced the well working length. Yeah so that's Yeah. So that's my that's my understanding of it. Thank you for that. Thank you. All right, tell me about bone grafts, so bone grafts used in orthopedics, either at a trauma setting to encourage fracture healing or for significant bone loss, or occasionally in the reconstructive setting for arthroplasty or occasionally for with tuba repair.
There can be allograft or autograft benefit of autograft is that there's no risk of bloodborne transmission. They, depending on what that is, it can act. It could be life blood cells. So they can have genetic properties. But the disadvantage is that there's a slight morbidity and already a limited amount of material allograft to the other hand, you could see we have infinite material that typically is processed food.
So it's not live bones. So it's not genetic and there is a theoretical risk of bloodborne disease transmission with that. You could also get xenografts, but we don't typically use those commonly. In terms of allograft processing, there is a stepwise progression, how we process allograft boon that can be 50 patients are screened for high risk behaviors and bloodborne virus checks and any previous systemic diseases such as cancer usually makes them ineligible.
The daughter board is then devoid of any soft tissues, is irradiated and is washed in an antibiotic and ethanol based wash that it's processed for packaging. You can have different types of, I guess, how bone grafting can work. So you can get postural conductive, inductive and genetic. So also, conductive is essentially a scaffold for bone to grow into and can give some mechanical properties.
Osteo inductive gives has some of the growth factors which encourage bone formation or genetic has a living bone cells which are capable of producing bone and can also have mechanical properties as well, depending on if that is a cortical or cancerous grafting. Then I guess there's difference of how bone graft is incorporated by the body, so you can sell a bone grafting.
This undergoes a process of crepe substitution. So when can tell bone grafting is used as a hematoma and an inflammatory phase similar to early bone healing, where there's vascular regrowth? You then get this creeping substitution where the body's osteoclasts to remove the cells will graft to get a new osteoblasts trabecular metric is laid down, and that results in a higher strength of the bone over the first few months.
And eventually that bone is completely replaced by the body. Whereas with the cortical graft, there is no creeping substitution and the there's a transitory weakness of the board over the first few months, and it's one of the best, of course, of cortical grafting. Remember, the alternative is a fibula, a sort of vascularized bone graft that essentially heals like a fracture wood with control calcification at the limits of the bone graft itself?
OK, what kind of factors would affect bone grafting corporation? So these could be thought of either as doda, the recipient bed and the systemic condition of the patient. So the doda, whether it's a live or genetic graft, or whether it's a process of tissue conductive, reductive and/or were grafted autographed for the tetu for the bone.
The bed, if it's well vascularized of the said infection and then the. So forget the third one, I guess do for all the chemical environment in foods that add systemic conditions. Sorry, if the patient has had smoking diabetes, poor manage comorbidities could also influence that Building Corporation. Yeah OK, good.
That's five minutes. So how do you think you did, jamie? Yeah OK, a few bits. So it wasn't that slick with, but I guess that you could talk for five minutes, which Yeah. Yeah, and that's just what I let you do because, you know, I think provided you're talking, you're ticking the boxes. It's all fine. So this is from ramachandran, which just goes through.
The different so you could be asked, what's the difference between osteogenic Austria conductive inductive? It could be our slap. And then you kind of touched on this the advantages and disadvantages or the different types of bone graft, as you say, xenograft, we don't really use keel bone. I had to just look that up, actually.
Apparently, it's calf that's been treated with hydrogen peroxide and then acetone or something. But as far as I can see, all the studies are from the sixties, '70s and eighties, and it doesn't incorporate, but that's in the most recent edition of Ramachandran. So there you go. The other way this question could go is you could talk about bone graft substitutes, but I'll save that for another thing.
Now there was only one thing I was going to pick you up on. Yeah, when you talked about cortical grafting corporation, so it incorporates via cutting cones to incorporate the grafts. So you have the cutting cones. Which go in first, which is why you have that initial loss of mechanical strength and then. You then get the new bone formation and it grows in that way, followed by the blood vessels and it's incorporated.
OK, thank you. Vascular wise graft. Yes, you mentioned that I was going to come to that. Factors affecting incorporation, as you said, systemic. So all the smoking. Diabetes, all of that stuff, the mechanical environment of the graph itself and the quality of the host bed, as you said.
You need cells in the host bed, which might be deficient if you've had some kind of radiotherapy or if you've had a previous infection, or if you've got poor vascular supply. So if you've had a massive open fracture with all the soft tissue stripped and you then try and graft it, you might not grab, might not incorporate as well as it could.
And if you've got an immunocompromised host, so yeah, I think you covered everything there that I wanted to cover. You just described osteogenesis conduction induction. So, yeah, again, I think you've all done really well on this section. There are some questions this picture. OK what can you see?
OK, so I can see this is a picture from the clinical picture, from the water aspect, I can see there is an attempt of repair of possible tendon injury and their little finger and. My so this is a zone to injury of the flexor tendons and. And that is between the attachment of the tendon on the metal pellets and see a extended little finger when other fingers are flat in you suspect the tendon injury.
Yeah, really. So what I can see is the extended little finger, and I suspect there is a flight attendant injury. All right. Yeah so how would you assess injury to tendons? OK, so the injury to the tendons I will assess by there, I will assess the tendon injury itself. I will assess the neurovascular status and I will assess the joint, which are caused by the tendon and also if there is any collateral injury in the form of both stringing signs or both stringing that point towards the how do you know, but the tendon is ruptured or not?
OK, so I will perform the tenodesis test that will be passive and active passive flexion and extension of the wrist. But seeing the excessive tendon flexor tendon injury, if in the extension of the wrist, the fingers will curl. That means that the tendons are intact on the passive flexion of the wrist. They should extend, if not, if they are, if they remain flexed.
That means there is extensor tendon rupture. All right. And any other way? I will perform of the individual test for the tendons. So like I will, I will. If there are two tendons passing the joint, I will exclude one tendon at a time and then assess the other tendon, like in the FDP and the base of the fingers I will exclude for testing the evidence.
I will exclude the isolated by not allowing the MVP to contract to look for the tendon rupture. So how are you going to do that? So, so part of the MVP tendon that is attached to the base of the distal phalanx or aspect, I will stabilize the finger from the middle phalanx and ask them as them to flex their fingers. So I'm basically testing for the MBP, for the fdis because it has got common belly.
So if I block the flexion of the rest of the tendon, so the tendon, so the tendon, I will be able to isolate the function of the assess the base of the middle finger by blocking the rest of the tendon. What has the common belly? So sorry, MVP. MVP has the common belly.
OK, so you're blocking this so that you can see Yes. Yeah so this STP of ideas is disturbing. You are talking about the 28 flexo-pronator companies, but they arranged how are they arranged? OK, so the MVP are the most deep tendons. So they are arranged in a single row and every tendon are arranged. The third and the fourth tendon is more dorsal and the second and the fifth and tendons are smaller, and they are arranged in 2 and 2 stacks.
That's of the flex. The students standard is superficial to flex the strength and resilience, and all the fingers are there in the same plane like or any different plane. The FDA stand-in, all the FDA standards are they arranged in one plane or different place? Oh Yeah. So that is what I said. I mean the second and the third FDA is for the second and the third or second and the fifth finger.
They are arranged regularly and the third and the fourth, they are arranged to doses. So if the FDA standard is more roller to FTP tendon, how does it insert on the proximal phalanx? OK, so at the level of the pipe joint, the BP stand tendon this split and they form a camper charisma and they go on to insert a bit of the truth and to underneath the tent passes under the camera plasma.
OK, so that's fine. So this is a tendon injury of little finger is thrown both ethically and yes, OK. How would you repair it? And then can you tell me the principle of tendon? Repealed Yeah. So tendon repair, especially in the zone two, should be repaired as soon as possible because there is a high chance of adhesions where blood supply and work results and immediate rehabilitation should be sought.
The principles are to get a 4 to six core sutures, which is with the non absorbable sutures. The tendon thins should be handled delicately and the suture should be get. We should get the go. Such sutures at least 8 to 1 8 to 10 millimeters across the cut ends, and they provide 80% of the strength to the tendon. And then this is followed by tenderness, circumferential sutures, which provide 20% of the strength.
They are mainly to tidy up the repair and to allow for the easy gliding. Also, I have to take care of if there is any nerve injury I can, I will repair it with the axilo or non-zero proline, and they should be done this before not doing repair. Yeah have you done it yourself? You're done it. Ok? yeah, that's fine. So your repaired the tendon, OK with Goran and epicondyle Kessler suture.
OK, what else you're going to repair? So I will. We're going to get I guess we better this year, isn't it? Yeah, repaired the sheet and I don't know, I'm just before that. At the moment, we will repair the tendon of the yard to prevent the boys thinking how to take care of the police as well, especially the egawa and the airport police.
I have to repair them if they are completely damaged. I will repair them with the EPDS tendon. All right to you're going to reconstruct it. I'm going to reconstruct it. So you're done the repair. OK what position you want to kick the hand? So there are two basically the reflections you are or are not involved, you are in the now repaired and then just no, and how are you going to keep the I'm going to keep it in the Edinburgh position and blocking the extension, and I didn't position that is the extension at the pipe, at the inter-provincial joint and the flexion at the MCP joint to allow for the maximum extent of the collaterals maximum stretch of the collaterals.
OK all right. This is basically you're keeping it in that position where you are going to slap, tuberosity or Walla. So I will put the slap dorsally to start with and but I will Institute a range of movement that will be Cooperative Extension into hand in hand. What is the principle of hand therapy? So the principle of hand therapy is to get active extension as soon as possible, and then the passive collection can be by the splint assisted or by the patient assisted.
So the idea is to get an active wrist extension in case of flexor tendon repair and the patient or the splint assisted the passive flexion. Look, you are to prevent the stretching of tendon. Basically, isn't it always stretching? Yeah what can be the complications of the tendon repair? So there could be various complications like adhesions of the tendon or there could be real rupture of the tendon.
There could be cotija effect. There could be contractures and repair failure, as I already said. What is it or is that? So whenever one of the tendon is repaired or as a result of trauma, it heals in a more contracted position in then, while making the grip, that finger will contact the palm first and lead to the inefficiency of contraction of the tendon should be tied to get Corica effect.
So the tendon, which is repaired that will be more contracted and it will contact the pump first and arm first, isn't it? OK, that's fine. You're done well, ok? Just needs to be tidying up. So first thing when you are, I told you last time also when you see the like photographs like this, ok? Why don't you tell? Just do I do tell you?
You say that right? The little finger is kept an attitude of extension. I think there might be tendon injury. You are actually giving a lot of information to somebody and making yourself clear by just saying few words like this, rather than just saying it is like the static scar. OK, then your answer this assessing tendon injuries first inspection.
OK they'll be abnormal push like you can see in this case, you assess the acute contraction of tendon that you demonstrate and pursue tenodesis that also you told me egawa tendon plays. You are quite good, but you put it in a much easier way. I think like at that level of the wrist, the FDA, the same playing and are in this. So this attitude of principles of tendon surgery is first automated technique, it can be done under anesthesia or wide awake.
First, this repair could give 4 to six core sutures. OK, and all around you epicondylitis sutures. All right. Repair the sheet, OK, and place the tendon in a position of protection and referred to hand physiotherapy, which actually there are various protocols. I don't know, but basically they allow the flexion but prevent the extension of the stretching of the tendon.
All right. Complications, you can say there are general complications like infection, but basically complications are adhesions and rupture. OK, now Quadriga effect is specific to the flexor tendon when it is suture tightened with the fingertip register from before the other fingers. So you got a rough injury of your ring finger and you put it in tight with rich finger before other fingers.
All right. OK so. And then little plus sign, you know, the about that, isn't it? People, when you know, when the repair is not good, the poles get transmitted to land because then it paradoxically extended. What you'll get there, but they are much better. I just try to refine your language, not technical, you know, quite a bit.
You added the organization of knowledge is good, but the wording is wording is what you are lacking. So what do you see? Is the language, you know? Yeah OK. All right, guys. OK, thank you. Well, this is the.
The principle of tendon repair is Kessler suture circumferential centimeter repair of sheet and mobilization. All right. So who is going next? Survival analysis? OK I will do a survival analysis using either a kaplan-meier code or using an actuarial method.
So actual method normal is done at a fixed intervals and the kaplan-meier code analysis is done at the time of failure. For example, in orthopedics, it is done at the time of revision. For example, if we are talking about total hip replacement or a knee replacement and so this is so I would take here is a kaplan-meier code, for an example.
So it is part and it's a time which one you prefer. You're doing like using a table. What are you going to do like couple kaplan-meier? I would prefer to use an kaplan-meier. Why I say this is the number one, the reason is I can analyze at the time of failure instead of doing it at a fix, it ensures there are pros and cons on both sides. But I would prefer to use this one because I can analyze at the time of failure, because that is a significant event.
If I say that's the one thing under the kaplan-meier code has got various characteristics and also it allows variable dates of entry and then follow up as well. And so I can compare that to implant performances at the same time. Uh, OK. OK, tell me here, so what's that?
What's that? So this is the. This is the survival analysis table. No, I'm not sure. Yes, you are right. That's what happens is a bit small. I'm just zooming in. I'm really sorry. So yeah, I can see the time interval on my left side and I can see no at risk.
And so I can see the number of events. I think that denoted that denotes the failure. And also the survival is calculated here. And also, we are getting the confidence interval accordingly based on the sample population. So it's. So the confidence interval mean it's a 2 standard error of the mean either side of the sample mean. So if you say 95% confidence interval, that means that true population mean lies within the we are 98% confident that true population mean lies within that range.
And usually the confidence band, normally in a venue, draw a cap and my call is become wider. If if the sample size becomes narrower or a smaller on the side, each time when the failure happens, we do some mathematical calculations. So we do that number at risk and then we see from that we will calculate a percentage of failure rate from the percentage of failure rate.
We calculate percentage of success rate and the cumulative probability of failure. And from there we will get the probability of survival. So then once we get the probability of survival, we put it in the vertical axis. And then the horizontal axis we will draw over time. So then we will get the cap on medical. OK OK. So, yeah, tell me what you see here in this, yeah, so this is a nicely plotted the kaplan-meier code is, I think, the time against the probability of survival, the central line, which is I'm interested in to describe to start with, in which the vertical dip, which indicates the time of failure here this rubicon, the small vertical blips at the center of the horizontal line, which indicates is a right censoring.
So the right censoring means it's a withdrawal spike is the loss to if the patient is lost to follow up or a death. And these are all the right censoring and say and also I can see the confidence band is getting widened when the time goes up. And that means that the sample size is getting replaced. And so my left side of my code, the numbers are at risk.
I have and the right set of my code, the number of failures. And as well as the number of the towers. OK, so, OK, so which which was this line, you see my arrow? Yeah, I can see that the daughter, the dotted lines at this indicate the confidence band. OK so, OK, so what do you think you did? I think I was trying to give some structure and you did well, but but there is I will tell you how to answer these questions.
Yeah so if I examine you, I will pass you. I'll give you six. Yeah but I will tell you now how you can get eight easily with the same information you have. Yeah, you're not at anything. Just polishing your answer. OK, so let's start again. Yeah OK, so this is OK. Survival analysis, OK, so definition, so the outcome of intervention is plotted over time, so we didn't mention the intervention definition, which is the starting point of your answer.
So start your answer with your definition. So what survival analysis is an outcome of if intervention is plotted over time, which allows for variable date for that of entry and different lengths of follow up? Yeah OK, so I can like do for over 2 years, five years, 10 years, and I can measure any loss of full above two years, five years, lots of follow up of patients.
So I started with 100 end of this. My research with 80 patients, I have 20 patients lost of follow up. I still can do a survivor. Analysis for the procedure is like a new head, a new procedures, whatever. Yeah, OK, how you can do that? OK there is a low equatorial life table, which is mentioned here.
Yeah, and time of failure. Let's give you definitions. So instead of saying equatorial life table method, I will say definition is a fixed intervals and times of failure. So fixed intervals represent equatorial life. Table method yeah, OK. And there is a time for failure which kaplan-meier. Yeah OK. OK how to construct a life table for joint replacement for an example.
OK the end points, you have to be defined. OK, which is usually revision, so if you your example is a new prostheses for hip replacement, the endpoint to be defined here is the revision. Yeah, OK. Yeah and the number of joint followed of joint being followed and the number of failures are determined for each year after operation. So as I told you, we're doing for up two years, five years, 10 years, and we'll measure the failure of the which is by definition, here is the revision.
Yeah OK. And for each time period, number of patients at risk, like painful hep, maybe infection, all the things and the number of failure and the number of withdrawals you have to be recorded as well. So how many patients like has been withdrawn for sometimes you're also full of the patient is very happy. That couldn't be counted as a failure or revision because the patient maybe didn't attend the follow up clinic because it's very happy, very impressed.
And he thinks that no need to come to see the doctor. Yeah, OK. Yeah so then this is the kaplan-meier graph. So when you see that the way I'd like you to answer no one, it's definition outcome of intervention plotted over time the X time. So now you, you will like identify everything. So let's start with the X-axis and y-axis.
The line in the middle, the two dotted lines and after that describe the other things you started with the sensors, with the steps. Yeah so you started from the end and then you came back to the beginning. So you mentioned everything. I am very pleased with your answer, but now this is better if you extra mark with the same information with the same knowledge.
Yeah OK, so this is the definition defined, defined first. I see. Except whatever. OK, I see like this is the kaplan-meier is the outcome of intervention over time. Always remember this definition. Yeah, OK, it's x, which is the time elapses. The y represents the percentage of the population surviving.
So how many patients now to the 50? So by the time the number decreased? Is it ok? Does it make sense? Yeah Yeah. I thought of y axis, they say, the probability of survival on the vertical axis, so I'm a bit confused here. Is it outcome of intervention?
Does it mean like the does it denote the probability of survival? Yes, the same thing. So the number of yeah, Yeah. And there is OK, the dotted lines. This is the confidence interval you mentioned that. So the dotted lines are confidence interval and there is and now you will describe what's in between. OK, so increased over time due to decrease the number of patients, yeah, less reliable data towards the right, which is the right side of the blood to represent best and worst case scenario.
And the other, which ones our dotted line assume all lost fill up it and the law assumes they all failed. Important to compare between the tuberosity can tell difference if there is no overlap. So, OK, that's really nice. Yeah, thank you. Yeah and there is a sense of the lost patients I didn't find was the little mark.
Subjects that are uncooperative or refuse to remain in study. So that it shouldn't be considered failure. Yeah, OK. Don't experience, event or die. Maybe die from heart attack or anything. Not from tuberosity. Yeah so before the end of the study, or they lost to follow up, they is the most important sentence here.
They don't count that as a failure. Yeah, OK. So I will try it again. So this is kaplan-meier number two definition. Number 3 is X and yz four. Four OK. Number four the dotted lines number five. Something in between. OK and the bigger one and then the smaller one.
Yeah, which is a small sensor. Yeah is that clear? Yeah, absolutely. Thank you so much. That's so answer. So you have the knowledge, but the way you've answered and do not miss anything if you have a technique of 4 and 4 to answer these questions. Yeah so sorry, can I ask a question?
The vertical line is that what? What shows that? Or is it the is a transverse line which goes beyond? No, the transfers line is the time. Mm-hmm And on the main, I mean, the main axis is the no. So with time, the number is increased and you see the confidence interval here between the two dotted lines become widen because you lost a follow up due to like many things.
No already like loss of follow up, maybe revisions. Maybe patient die. If if it's a loss of follow up, will it be a vertical line or a transversal? What you mean here? No, here, here. You know, This is this is like, this is no, this is a revision. So this is the steps is the revision. The census is a long lost follow up.
It is a small sensor here. That one, ok? That's fine. Yeah, that's right. Yeah the steps is the revisions, and the one step is the revision and the line is essential. Yeah, exactly. OK, Thanks.
OK so who is the next?
Segment:0 .
If I got one for you, here we go to particular next week as well, isn't it?
Yeah Yes. Yeah thank you. All right. So we've got a 50-year-old male. He's been in a road traffic collagen. We've done Atlas. These are his scans. Let's say we're going to take him to theater. All right.
Everything else is done. Anaesthetist ICU. We've decided that we're going to take him to theater and we're going to reduce this and fix it with an CDF. OK, so tell me about your approach. OK, so I'll divide my management in the theaters, I will divide it into clusters of patient positioning because this is bilateral dislocation, so I will be very careful with the patient positioning.
So there will be in terms of positioning, I will put a sandbag under the scapula. The head end up by 30 degrees, neck extended, rotated to the other side. So I prefer doing it from the right side to the. The head would be slightly rotated to the other side, making sure that there is no increase. There is no neurovascular deficit. And if there, I will be very careful.
If there is any neurovascular deficit, I will be stopping it there and then I will position the image intensifier checking, making, doing a level check. My incision will be a transverse incision at the level of the. Six seven cervical vertebra of the extent would be from the midline to the left to the bottom of the standard mastoid skin, subcutaneous tissue and the investing layer of the cervical fascia is the first layer along with I will like it the external jugular vein, which comes laterally.
Following this, my plane of dissection would be on the lateral side. It will be the carotid sheath, including the carotid vessels, the vagus nerve and the internal jugular vein. On the lateral side, it will be the standard thread and the strand hard muscle. Following this doing this at this time, I will get the superior and the inferior arteries, which will come in the field.
Following this, I will have the so that sort of Standard Chartered and how it goes along with the pre tracheal fascia. Next, I will encounter the esophagus, the esophagus and the trachea dissected immediately. Following that, I will have the prevertebral fascia I will inside the pre-verbal fascia, making sure that the longest kaleigh muscle, along with the sympathetic trunk, are taken off from the bone and dissected laterally.
And I will come onto the vertebral onto the entire surface of the vertebra. I will reduce. I will first. I will do that to me. I will. And then followed by a reduction. If the reduction is achievable, then I will fix it with a cage and and plate.
If the reduction is not achievable, then I might have to consider a fuel reduction maneuver, which involves hyperextension. If not, then I have to preliminary I will fix it entirely. Temporary fixation to make the patient prone and remove any block in reduction was clearly fixed positively. Then again, come back in a position and do the definitive fixation in the anterior position.
OK, that's good. Pretty definitely a high pass from me. I don't think I hide anything else. I agree with your positioning. Yeah you said you were going to go on the right side, it doesn't matter which side you go on. I tend to go on the left.
Just because of the recurrent right? The recurrent laryngeal nerve. But it doesn't matter provided, you know, provided you have a reason why you're going one way or the other. So these are landmarks. So your mandible is key to your hyoid C3, your thyroid cartilage is C4 C5, you're quite C6, which is where you were going to go.
And then see 6 to 1 is down here. Do we need to mention this in the approach. Or is it OK to just? And I think in that one way you can say, I think it was C five, wasn't it? So I think you can say, look, my landmarks would be the cry coin at C six, because that's going to be the most palpable.
And probably the thyroid cartilage for that one, if you're going to go higher, then you should probably mention the hyoid. But then the I mean, you said you were going to check with I would probably double check with when you get down to stripping off the longest collie as well. So you talked about superficial fascia, but is my external jugular vein.
It's around the neck splits around CUCM and trapezius. The tracheal fascia, which is continuous with the carotid sheath, your superior inferior thyroid vessels run from the sheath to the midline, and they kind of the only structures that are passing medial to lateral when you see them in your approach. And in some ways, they do restrict your access, but you can locate them prevertebral fascia.
And of course, the sympathetic trunk runs on its surface, with the stellate postganglionic little bit lower down. So this is the diagram that you need to know. And so it just describes so it shows here how we've got the strap muscles, the thyroid. Trachea and esophagus. Retracted one way, and then we've got the carotid sheath and the stern applied a mastoid the other way so that we can come down onto the preferred crusher, which overloads the longest collie muscles and the anterior longitudinal ligament.
All right. So this is the diagram that you need to remember in your head when you get asked about this approach. OK and what else? Michael, for this one? Yes, so this is a technique and you basically talked through this and this is what you need to say. So the thing is you can do a transverse incision you got, but it kills me because it's within the line of the fibers.
But if you need to do multiple levels like, say, you've got a myeloma or something with multiple vertebrae you need to fuse, then you're going to have to go with a longitudinal incision. The multiple levels you split the plasma in the line of its fibers with your finger. think you said that identify the anterior border of ECM and inside the fracture longitudinally. Take it laterally.
Retract the strap muscles. The trachea and the esophagus immediately expose the carotid sheath. And this is the bit that I got grilled on in one of my exams, actually this part of this approach. So you want to develop this plain, that's why I put a bit more detail. You want to develop the plane between the carotid sheath and midline structures.
So that you can retract the sheath laterally with the stent, Clyde and mastoid to take it that way, like in the diagram. Oh, can I just quickly ask one thing? I mean, this critical fascia and the carotid sheath are continuous, I think. Yeah, Yep. So you need to size them, ok? And political pressure comes medially, and the carotid sheath with its content goes lightly.
That's the point that I got asked a lot in my exam. Um, exactly what I was going to do with the carotid sheath. So it's what it says. Superior inferior thyroid arteries that the medial collateral and then you basically need to work immediately. And go gently because you're going behind the esophagus. And then, as you said, down onto the prevertebral fascia in the midline.
Make sure you stick in the midline because you've got the sympathetic chain over the longest collar on each side. You split it longitudinally on the anterior longitudinal ligament and then you dissect it so periodically. And this is the only thing I would do different particular. I'm sure you do. It is when you get down to the actual vertebrae, I would probably put a needle in the disk and just check my level.
That's the only thing I'd do differently. Dangers, recurrent laryngeal nerve, so the injury rate reported in auto bullets is 2.3 percent, and there's no difference between the right side and the left side, which I think is why we say it doesn't matter which side you go on the right side. The recurrent laryngeal nerve is a little bit more variable and runs a little bit more of an anterolateral course and on the opposite side.
So it's slightly more vulnerable, which is why I go on the left on the left side. The recurrent radial nerve is slightly more protective, but you've got the thoracic duct on the left side. And so that's know, it's your choice, whichever one you want to go. But there's a risk to everything on it. You know, there's a risk with everything we do. So that she recurrent laryngeal nerve, the rusike duct C7 T1 sympathetic chain, Horner syndrome, the carotid sheath.
Any of these big red blue things is going to be bad. All right. Vertebral artery, inferior thyroid artery. And the other thing that you can mention is that if they develop a post-operative retropharyngeal hematoma, you need to decompress them because they can get OA compression. All right. That's it for this Ms Robinson approach.
Any questions is made up of a femoral device, and that's typekit a device on the femoral side that's composed of a stem. And that stem has a part that's in the data. The metathesis that has a neck with a trillion and then articulates with a ball. That ball is typically made of metal or ceramic. On the acetabular side, you have. Fantastic so obviously, we've got lots of surfaces here.
Tell me how they interact with each other. The surfaces of this looks like an unscented device. The surface is therefore based on friction and a press fit that interacts directly with the bone that can either be partially coated or uncoated, depending on the hydroxide hydroxide appetite, which will encourage in growth austere, conductive and on the interaction between the onion and the ball. That's again, a friction talk surface, usually the trinian's differential shape that can be based on the difference between the proximity of the engine and the ratio to the distal end that articulates on the inside with again a friction fit with the inside of the metal head, which is, you know, symmetrically shaped.
When we talk about interactions, we we're talking about typology. Now what is true symbology is such typology is the study of how materials interact with each other through friction. Is it just friction? It's through fiction, and I guess it's a study of how surfaces interact with each other in motion that includes friction and lubrication.
And so we know that what's more important for us is orthopedic surgeons. Lubrication and how much where there is at the implant interface, what is where then where is the loss of material due to motion? Is it just that or are there other ways of how it can happen? Where can either be chemical or mechanical? And I can talk through those types of wear.
So tell me about mechanical. Mechanical can be divided into abrasive adhesive and subsurface de lamination. Abrasive wear is when there's different types of wear there, when there's disparities which interact with each other and break off parts of the material. And that can be due to four types of where I can talk through those. Alternatively, yep, first point you wear is when to implant interfaces that are designed to interact wear out.
Second body is with an implant that intended on one surface were not intended on the other side. Third, body wear is when you have a loose body, for example, between two surfaces that are interacting and fourth body wear is when two non intended surfaces are interacting. OK, so tell me in terms of your experience, how has this affected your work? Where is affected, my work, particularly related to hip replacement in terms of reasons for revision.
For example, when we're choosing implants, we want implants that have low wear and high fatigue strength, low fracture risk as well and implants that are working under their endurance limit. So, for example, my preference is to use in active patients a cemented a ceramic on poly interface. That's because that's designed to have low where ceramic is as low friction and highly cross polyethylene has extremely low wear, with some compromise with fatigue and endurance.
OK all right, I think that's probably exhausted that one. It can be quite a dry topic, to be honest, where so dry theology, as I say so. So I'm part of that structure. So how do you think you went with that, kartik? I took some. I was trying to work out where to go with it. I think I knew the answers. It's just I was probably I need some advice as to how to get on with it.
Yeah so it can be quite difficult one in terms of they'll probably lead you along in some of the best, some of the basic science ones. What I would suggest is try and preempt them. So if they're so, they'll give you a little clue. So anatomy of an anatomy of a hip replacement? They will talk. They'll want to talk about the interaction between the different surfaces there.
Yes, I gave you on some medicine one. But normally you'll get a cemented one because I also want to know about the interaction between cement, the cement and metal interface as well. So there are all these different surfaces that they want you to go through. But actually, from overall, you were very good. You knew the answers you had. You did a little bit of prompting to get some things across, but that's fine.
Minimal prompting is all right. So from my point of view, we're very safe past, but obviously we're trying to Polish it up. So yes, technology, the science that deals with the interaction between surfaces such as and motion and the consequences of that interaction. They do like their definitions, so try and be a little bit more Precice with your definitions and where progressive loss of a bearing surface as a result of mechanical, of mechanical or chemical wear.
Now, mechanical wear can even be removed material from surface by mechanical action. So brace it at ease of fatigue and electrochemical. I don't want to go too much on that. I'll come later. So galvanic fretting, pitting corrosion. But the examiners will push you on to get everything. But I was very pleased you talked about a brace as well. He said, well, if fatigue won't discuss a bit later as well.
Then also in terms of moans of wear in the joint off, see how it can be done. You've talked about motion, the primary between two bearing surfaces, the expected motion between varying surfaces with a secondary non bearing surface, a head rubbing against the back liner. So try and involve a bit more experiences in terms of clinical application of it. So basic science.
They sometimes they want you to go. It can be a very dry topic. They want you to move on, sometimes onto the more sort of clinical side. So if you can apply the basic science scenario in a clinical scenario, that's what they want. That's push you towards a 7 and 8 and 2 and then obviously third body where stand in the shoes, for example, or two non bearing surfaces really get together trying it in the head.
Again, that's a big thing at the moment, and particularly for varsity. So if you can push some of that in, that's a good example of your understanding that you've got this good core basic knowledge and you're applying it in the clinical situation that way that's push you from at six, hopefully towards a 7 and an eight. OK does that make sense?
Got it. Absolutely thank you. There's any questions you like to ask. You no, again, it's just I was trying to give the examiners and you some points and I was hoping you just tell me, ok? Talk more about that. Otherwise, I'd have gone 10 minutes into chemical and gale galvanic corrosion, getting any points.
So is that appropriate to stop offer and then back off and then wait. Yes as I say, sometimes it will happen. If there's a gap, don't make it to on a gap. They will want that. They may want you to move on. But yes, I was happy you stopped because I wanted to move on to different topics such as the subject. If you're carrying on, don't worry the main problem.
That's great. That's fantastic. Can I just ask you about this or what can I pick up on? I pick you up on this. It's not necessarily then prompting you. Is this then there? I was happy with your answer, and I was trying to move you to get you to score more points. So the anatomy of describing a hip replacement, that's the starter opposite.
That's the relaxed, warm you up because everyone knows what hip replacement is. Hopefully not. You're in the wrong exam. But as I say, that's as I say, they always have a relaxing question and then to warm you up and then they'll push you onto the meat of it was a good understanding of where was and also good understanding of the different modes of where, as I say, the way how you can now improve that answer is applying it in that clinical scenario.
So that you can show and demonstrate that you are fit because we all supposedly have learnt this as part of our first years of being an orthopedic registrar, but it's how we apply it as an orthopedic surgeon. Yeah, in terms of did it quite well. When you're talking about the type of implants you talk, you want to pick up on as a hip surgeon, for example. OK, thank you. And that sometimes could be another question.
All right. So we'll move on to the next five minutes. So how each of these images created? What do you see here on the right? Start with the top one. As at the top one is a kernel image of the knee joint is the MRI scan of T2 weighted because the fluid looks bright. OK, so what's the MRI scan?
What's one of those so MRI stands for is a magnetic resonance imaging, which uses a superconducting magnets and radio frequency impulse to create an image. So this uses the principle of each atoms in our body as part of the hydrogen atoms. So which is responsible for these images? So fluid, the tissues, which consist of hydrogen atoms, each responds to these magnets.
And so when the tissue is placed under the magnets, what happens is the so before that the atom has got two functions. One is its spin along its axis, and the other function is as a politician. So when it spins, it also wobbles. So when the tissue is placed under the water standard, the atoms becomes a longitudinally aligned. And once the radiofrequency impulse is given, it is transversely placed on the time taken from the transverse alignment of the long alignment.
About 6% to 7% is 2 to one, and then the remaining is T2. And based on that, we will get it to you and waited and waited images. And again in T1 weighted images on the TR is a repetition sequence is both the repetition sequence and the echo sequence are shorter and then the both are longer in T2 weighted images. And also we got two different sequences is called the superior consequence and is the most commonly used.
And also there is a metal artifact reduction sequence, which is used in metal and metal. Yeah so and again, there are some potential advantages and disadvantages at the point of just being no radiation, no ionizing radiation risk. But the disadvantages is claustrophobic. Again, yeah, OK. So if we move on, what about the second image? What's that?
This is in a city currently. Image again. So the so again, the CT scan is an imaging modality, uses a radiation. So it's basically it uses a multiple X-ray sources and it is again, it has got a detector on the other side. So it's kind of a limited the X-ray source and then the detectors also receive another direction.
So instead of patient moving, it's they say here, it just circles around the patient and then we get a 3D picture. So that's the difference between the X-ray and then the CT scan is the multiple X-ray sources has been used here and then the and also the soft tissue and then the bony delineation is better in the CT scan. So soft tissue to use, so does not use to delineate.
Sorry, I meant that the CDC has not meant for a soft tissue details. However, when compared to the X-ray because the X-ray and say the X-ray images are produced based on a high beam, low beam attenuation. But here the CT scan will give a good delineation of bony details, and that nicely separates from the soft tissue details. OK, so you briefly mentioned attenuation.
What? what do you understand about that? And so the different, different tissues in our body, it's a differentially absorbed and the high energy electromagnetic radiation. So based on that, we will get the images. So the high beam attenuation means is there is an absorption is high and the low beam attenuation means its absorption is low. OK, where is it measured using any units?
And it is measured, and I think it's a millisieverts. so about the two, it's innovation, not the amount of radiation. Oh, sorry. So I'm not sure about the problem. That's right. And so, yeah, when would you use a CT scan? When would you typically order a CT scan?
What kind of clinical situations? Yeah, I'd say the CT scan is useful to delineate any particular fractures and then to and also this provides a three dimensional picture instead of two dimensional pictures and x-rays on the preoperative planning to. I think that's the time it time's up. It's five minutes is up. Good good, good.
Yeah, I think I think it started well with MRI scan. Probably the CT scan a little bit a stumble. Not the ivory did very well. Yeah, it's one of those is that, you know, you kind of learn it once upon a time and then you've got so much to learn. It kind of goes at the back. But but it's useful just to keep refreshing that.
So your MRI, you know, you mentioned everything. Can you hear me? Yeah, yeah, I can hear. So I just got a message. My internet is unstable, so I'll just make sure you cut out. OK? so, Yeah. MRI is good, too. You mentioned the very thing that once you do mention about, you spoke about the strong magnetic fields and the radiofrequency to close.
So you've got your atom spinning and then when you they line up with longitudinally, don't they? Then you apply radiofrequency pulse and they transversely which, which is what you mentioned in their possession also all lines up at the same time. And they mentioned about the T1 and T2. That's good. So yeah, it was the T one is the relaxation time, isn't it?
The two hour time is from when it goes from longitudinal organization to the recover 63% You mentioned 60 seven, so 63% of the normal once the radiofrequency is stopped and. T1 is good for anatomy, isn't it? It's good to show you anatomy data for pathologists. Yeah, teachers, for pathology, isn't it? So and that's the time from the transverse when the transverse magnetization vector decays by 37% know.
So it's 60 three, 30 seven, 30 seven, so, yeah, good you mentioned about the image that you saw the water's dark on to 1/2 is brighter and you're aware of the fact suppression. I think you mentioned the stir sequences and the Mars sequences, where the metal artifact reduction sequence, which which was good. Also throw in there the use of contrast, which is good to enhance the damage to tissue T1 way to insert something extra to throw in, which is very, very good.
So Uh, Yeah. MRI, so, you know, always, always useful to know about usage advantages and disadvantages. It sounds very basic, but it's always important to make sure you know, and obviously, as we know, it's good for soft tissues or cold fractures. Malignancy doesn't have any ionizing radiation like axilo, but is expensive, can be claustrophobic for patients. And obviously, you've got some precautions many pacemakers, ICDs and cardiac and brain, et cetera.
And cochlear implants something to the disadvantage about CTE. Again, I thought you did well, actually. You know, I think the only thing you need to really know about is the hinesville field unit has four units of attenuation. So just that water zero and then you've got bone is 1,000 and then there's minus 1,000. So you know, the water's in the middle between air and bone and that's the, you know, the marker of attenuation.
So you knew about that. You're able to describe how the modern CT scanners have developed. You've got the helical spiral ct, as well as it rotating the Gantry. You've also got the actual where the patient, the couch for the patient. Also moves. So it's not just a Gantry moves, but they're both moved together, so it speeds up even more now.
The it's also useful to throw in, because how is that different to an X ray? Well, you've got pixels and voxels, so you know, each so two days a pixel. But then when you've got a volume of tissue, the depth that becomes a vauxhall's, that's by definition, you know? So from the actual images, it then creates.
A 3D image and that each one of those volume of pixels called a Voxel. So these are little terms. So fan shaped X-ray beam tissue attenuation coefficient kaleena detectors pixels voxels. These little terms to throw in and obviously this advantage is know, it's radiation, isn't it? So that's the disadvantage.
So you've got to make sure you use it appropriately. But it's got massive advantages like predictive planning for nonunion unions, deformities, complex fractures, intra articular fractures, rings all the time debris. And then it's also useful to know about, you know, registered images with PET scans and things like that as well. That's good. I think that's five minutes of feedback. So what do you see here on the right?
So it's a plain radiograph showing a major fracture of the fema, which has been treated with an intermediary nail. OK, so intermediary nail is a load sharing, device sharing device. A not necessarily can you can't put compression across it in case of a hind foot nail. So if it's not a load sharing device, what is it load bearing?
So, so when might be a load bearing device? I'm like, like a total knee replacement with as a nail when using a nail. Like, if you have a comminuted area and you want to maintain the length or will become a more of a load bearing, isn't it, rather than load bearing in this situation?
The whole concept is applied here. So in this situation, the concept is load sharing. Yeah so there is bone to bone contact at the fracture site. OK so, yeah, good. What do you understand about working length of a nail? So the working length of a nail is the nail, which the part of the nail, which is free from being in contact with any surfaces.
So for example, in this case, the screw at the bottom and the press fit at the fracture, at the estimates is the working length, the distal end and then the proximal end is from the other screw to the or even the metal facial area where it's attached to the fracture site. OK so when you ream the femur.
You have a really tight fitting. Dale, Yeah. Where's the working leg there? So in the tight fitting nail you? It's from the screw, from the locking screw to the area of the instrument. So where was what from the distal screw, from the proximal screw to the estimates and instruments to the distal screw so that they'll be the working land where you feel?
So the area, the area of contact with the bone could be more than just a point. So the surface area where it is touched from the distal end of that surface area to the locking screw of the bottom? OK, we'll come back onto that, but just one more thing. So do you solid or hollow nails and what's the difference between them? So I use a hollow nail.
The difference is that the strength of the material is stronger with the same diameter nail for the same material. But the flexibility of the nail is reduced when you use a solid nail, so the risk of breakage is higher. And also in ease of insertion is better with a hollow nail.
There is also the moment of inertia is also better with hollow nail because the difference between the inner and outer diameter nail, which which helps. But OK, if I can just stop you there for a second. So but obviously, a more solid nail at the same time, it is a hollow nail. Surely this so there will be stiffer than hollow now.
Yes, it's solid. Yeah, that's true. So the solid nail is more stiffer, and therefore it's more there's the elasticity of the nail is reduced compared to bone. So therefore there's a mismatch of the elasticity between the bone and the nail is higher with the solid nail. So a hollow nail would give you a bit more flexibility, relative flexibility.
OK you mentioned about. So I think that's five minutes up, isn't it? OK right? Just move on, go through things. How do you think that went? I don't know if I was clear with the working men, actually. OK, fine. Welcome up.
Welcome on to that. Yeah so. Axilo sharing a load bearing. It depends on what you're doing, isn't it, so. You know, to just kind be clear about that and don't get to. Fixed with our nail has to be load sharing, but it depends if you've got a significantly smashed up FEMA. And you're bridging it with a nail.
Well, it's not quite bearing, isn't it, anymore, you know, sharing. So it's, you know, it's going to be bearing more, isn't it? Yeah so, you know, you just have to be careful. It's not. It's a concept, not as kind of, you know. It's not a device, its concept, isn't it, of what's happening mechanically, so that's one. The second thing with the working length.
I think so. If you've got no Islamist contact, then the working length fair enough, is between the two screws. Yeah, but if you've got. A lot of contact in this miss. You've renamed you put a big nail in the biggest. You can then the working length is the contact area there nothing to do with the screws?
Oh, OK. OK so that is your working life. And so. That's important to just bear in mind with the work length of a nail. So that's why you want as much contact in this one, you put a bigger nail just stiffer, you know, to. You've got as much contact, bony contact as possible as well.
Is that is that clear? Yeah so in a dream now when you remake the tightest, most like in this case, you can say, actually the working length is quite short and it's within the isthmus because it seems to be a good amount of contact. Yes, for example, an elderly patient that, you know, they're proximal femur, if they've got a reverse oblique microfracture or whatever they might have and you nail it.
They have quite capacious canal, don't they? Um, and the working length in that situation is between the hip screw and the distal locking screws, isn't it? Right that's the. That would be working in that situation. Then this one is slightly different. Right, carry on to the next thing about sölden Holland. What do you think this was sort of probing about?
What do you think this sort of was trying to tease out of you? Is the difference between a hollow nail with the two diameters and the solid nail with a single diameter? It's talking more about this sort of second moment of inertia, isn't it? Yeah um, and understanding that together with Poland moment of inertia as well. Now The when denial is the whole point is it's like bone, isn't it?
The whole point is the second moment of inertia measures the cross sectional distribution of material from the center. OK, so it's the amount of material outwards. And so you think, well, OK, there's not much material in the middle. It should be less stiff, et cetera. Should have less bending stiffness and torsional stiffness, but actually with the same material.
Because you've distributed it further away. It's better than a solid network, because in the middle, that material doesn't have much resistance to bending or torsion. OK and that's and that happens in biology, doesn't it, as we get older, our bones. Become more hollow and make a bigger, more load is distributed further to try and compensate for the structural deficiencies as we age to try and give us a stiffer bone.
And that's what happens. OK, so so this is talking about second moment of inertia, which, for a hollow nail, a solid now. I've not put the equations here, but it's pie art to the fore, isn't it? Which which is. Different for Holland now, because you need to subtract the radius of the outer circle in the inner. And, you know, to be absolutely accurate about the actual second moment of inertia of a hollow a solid now.
So the second wave of inertia is it's also known as every moment of inertia. And that's. Regarding bending stiffness, but you've also got polar moment of inertia, which is talks about the torsional stiffness of the nail, so that's all about the, you know, the torsion rather than the bending. So they're both their forces, but in different planes, aren't they so?
It's just important to understand those principles, because that's what I'll be getting at and trying to come at you from a different angle, just trying to see whether you understand the differences between the two types and those two. Principles, moment, inertia and the second momentum. Well, Yeah. Thank you. Is that clear, so I think I think you just need to revise that a little bit and just horrify that bit in your head because it's easily confused when you sort of.
Here to battle in an exam. Yeah was that right? Yeah, thank you. OK right. So I think I've got a good game, there's one question if you don't mind just critical thinking to make a comment. Yeah, I'm actually a bit confused about the working lens, so I know that the working length is the length of unsupported bone.
But if you rim and then you provide a nail with good aesthetic fit, you mentioned that the working length is therefore the length has got aesthetic fit. If you have a better fit nail, wouldn't there be more bone contact and therefore a bigger working length by the definition? So your area of contact is where is that really going to be? It's not going to be proximally or distally in the metathesis.
It's going to be because that's the tightest part of the femur, isn't it? You know, whenever we look to nail a bone, we always look at the isthmus. How tight is that going to be? Am I going to put nail down there because that's going to be the tightest bit. So really, that's going to be where your contact area is. You reduce the definition change.
It goes from working length is the length of unsupported bone to suddenly the working length being the length of supported or contact bone. So so your working length in the where there's no there's no contact is between the two areas of support, which is the two screws either end. Yeah and. Because I think is it ramachandra, some of the kind of, you know, they just talk about that, but in the nail.
Unlike in a plate and a plate, it's quite straightforward. It's just between the two, you know, screws either end of the fracture site is the working length. But in the nail, you also have the contact within the space. So it because that's going to be, you know, that's going to be taking some of the support in the actual area of contact in Midland Bowen. It's my show.
So therefore, the working length is the area between unsupported bone minus the area of the ethnic fit and therefore you've reduced the well working length. Yeah so that's Yeah. So that's my that's my understanding of it. Thank you for that. Thank you. All right, tell me about bone grafts, so bone grafts used in orthopedics, either at a trauma setting to encourage fracture healing or for significant bone loss, or occasionally in the reconstructive setting for arthroplasty or occasionally for with tuba repair.
There can be allograft or autograft benefit of autograft is that there's no risk of bloodborne transmission. They, depending on what that is, it can act. It could be life blood cells. So they can have genetic properties. But the disadvantage is that there's a slight morbidity and already a limited amount of material allograft to the other hand, you could see we have infinite material that typically is processed food.
So it's not live bones. So it's not genetic and there is a theoretical risk of bloodborne disease transmission with that. You could also get xenografts, but we don't typically use those commonly. In terms of allograft processing, there is a stepwise progression, how we process allograft boon that can be 50 patients are screened for high risk behaviors and bloodborne virus checks and any previous systemic diseases such as cancer usually makes them ineligible.
The daughter board is then devoid of any soft tissues, is irradiated and is washed in an antibiotic and ethanol based wash that it's processed for packaging. You can have different types of, I guess, how bone grafting can work. So you can get postural conductive, inductive and genetic. So also, conductive is essentially a scaffold for bone to grow into and can give some mechanical properties.
Osteo inductive gives has some of the growth factors which encourage bone formation or genetic has a living bone cells which are capable of producing bone and can also have mechanical properties as well, depending on if that is a cortical or cancerous grafting. Then I guess there's difference of how bone graft is incorporated by the body, so you can sell a bone grafting.
This undergoes a process of crepe substitution. So when can tell bone grafting is used as a hematoma and an inflammatory phase similar to early bone healing, where there's vascular regrowth? You then get this creeping substitution where the body's osteoclasts to remove the cells will graft to get a new osteoblasts trabecular metric is laid down, and that results in a higher strength of the bone over the first few months.
And eventually that bone is completely replaced by the body. Whereas with the cortical graft, there is no creeping substitution and the there's a transitory weakness of the board over the first few months, and it's one of the best, of course, of cortical grafting. Remember, the alternative is a fibula, a sort of vascularized bone graft that essentially heals like a fracture wood with control calcification at the limits of the bone graft itself?
OK, what kind of factors would affect bone grafting corporation? So these could be thought of either as doda, the recipient bed and the systemic condition of the patient. So the doda, whether it's a live or genetic graft, or whether it's a process of tissue conductive, reductive and/or were grafted autographed for the tetu for the bone.
The bed, if it's well vascularized of the said infection and then the. So forget the third one, I guess do for all the chemical environment in foods that add systemic conditions. Sorry, if the patient has had smoking diabetes, poor manage comorbidities could also influence that Building Corporation. Yeah OK, good.
That's five minutes. So how do you think you did, jamie? Yeah OK, a few bits. So it wasn't that slick with, but I guess that you could talk for five minutes, which Yeah. Yeah, and that's just what I let you do because, you know, I think provided you're talking, you're ticking the boxes. It's all fine. So this is from ramachandran, which just goes through.
The different so you could be asked, what's the difference between osteogenic Austria conductive inductive? It could be our slap. And then you kind of touched on this the advantages and disadvantages or the different types of bone graft, as you say, xenograft, we don't really use keel bone. I had to just look that up, actually.
Apparently, it's calf that's been treated with hydrogen peroxide and then acetone or something. But as far as I can see, all the studies are from the sixties, '70s and eighties, and it doesn't incorporate, but that's in the most recent edition of Ramachandran. So there you go. The other way this question could go is you could talk about bone graft substitutes, but I'll save that for another thing.
Now there was only one thing I was going to pick you up on. Yeah, when you talked about cortical grafting corporation, so it incorporates via cutting cones to incorporate the grafts. So you have the cutting cones. Which go in first, which is why you have that initial loss of mechanical strength and then. You then get the new bone formation and it grows in that way, followed by the blood vessels and it's incorporated.
OK, thank you. Vascular wise graft. Yes, you mentioned that I was going to come to that. Factors affecting incorporation, as you said, systemic. So all the smoking. Diabetes, all of that stuff, the mechanical environment of the graph itself and the quality of the host bed, as you said.
You need cells in the host bed, which might be deficient if you've had some kind of radiotherapy or if you've had a previous infection, or if you've got poor vascular supply. So if you've had a massive open fracture with all the soft tissue stripped and you then try and graft it, you might not grab, might not incorporate as well as it could.
And if you've got an immunocompromised host, so yeah, I think you covered everything there that I wanted to cover. You just described osteogenesis conduction induction. So, yeah, again, I think you've all done really well on this section. There are some questions this picture. OK what can you see?
OK, so I can see this is a picture from the clinical picture, from the water aspect, I can see there is an attempt of repair of possible tendon injury and their little finger and. My so this is a zone to injury of the flexor tendons and. And that is between the attachment of the tendon on the metal pellets and see a extended little finger when other fingers are flat in you suspect the tendon injury.
Yeah, really. So what I can see is the extended little finger, and I suspect there is a flight attendant injury. All right. Yeah so how would you assess injury to tendons? OK, so the injury to the tendons I will assess by there, I will assess the tendon injury itself. I will assess the neurovascular status and I will assess the joint, which are caused by the tendon and also if there is any collateral injury in the form of both stringing signs or both stringing that point towards the how do you know, but the tendon is ruptured or not?
OK, so I will perform the tenodesis test that will be passive and active passive flexion and extension of the wrist. But seeing the excessive tendon flexor tendon injury, if in the extension of the wrist, the fingers will curl. That means that the tendons are intact on the passive flexion of the wrist. They should extend, if not, if they are, if they remain flexed.
That means there is extensor tendon rupture. All right. And any other way? I will perform of the individual test for the tendons. So like I will, I will. If there are two tendons passing the joint, I will exclude one tendon at a time and then assess the other tendon, like in the FDP and the base of the fingers I will exclude for testing the evidence.
I will exclude the isolated by not allowing the MVP to contract to look for the tendon rupture. So how are you going to do that? So, so part of the MVP tendon that is attached to the base of the distal phalanx or aspect, I will stabilize the finger from the middle phalanx and ask them as them to flex their fingers. So I'm basically testing for the MBP, for the fdis because it has got common belly.
So if I block the flexion of the rest of the tendon, so the tendon, so the tendon, I will be able to isolate the function of the assess the base of the middle finger by blocking the rest of the tendon. What has the common belly? So sorry, MVP. MVP has the common belly.
OK, so you're blocking this so that you can see Yes. Yeah so this STP of ideas is disturbing. You are talking about the 28 flexo-pronator companies, but they arranged how are they arranged? OK, so the MVP are the most deep tendons. So they are arranged in a single row and every tendon are arranged. The third and the fourth tendon is more dorsal and the second and the fifth and tendons are smaller, and they are arranged in 2 and 2 stacks.
That's of the flex. The students standard is superficial to flex the strength and resilience, and all the fingers are there in the same plane like or any different plane. The FDA stand-in, all the FDA standards are they arranged in one plane or different place? Oh Yeah. So that is what I said. I mean the second and the third FDA is for the second and the third or second and the fifth finger.
They are arranged regularly and the third and the fourth, they are arranged to doses. So if the FDA standard is more roller to FTP tendon, how does it insert on the proximal phalanx? OK, so at the level of the pipe joint, the BP stand tendon this split and they form a camper charisma and they go on to insert a bit of the truth and to underneath the tent passes under the camera plasma.
OK, so that's fine. So this is a tendon injury of little finger is thrown both ethically and yes, OK. How would you repair it? And then can you tell me the principle of tendon? Repealed Yeah. So tendon repair, especially in the zone two, should be repaired as soon as possible because there is a high chance of adhesions where blood supply and work results and immediate rehabilitation should be sought.
The principles are to get a 4 to six core sutures, which is with the non absorbable sutures. The tendon thins should be handled delicately and the suture should be get. We should get the go. Such sutures at least 8 to 1 8 to 10 millimeters across the cut ends, and they provide 80% of the strength to the tendon. And then this is followed by tenderness, circumferential sutures, which provide 20% of the strength.
They are mainly to tidy up the repair and to allow for the easy gliding. Also, I have to take care of if there is any nerve injury I can, I will repair it with the axilo or non-zero proline, and they should be done this before not doing repair. Yeah have you done it yourself? You're done it. Ok? yeah, that's fine. So your repaired the tendon, OK with Goran and epicondyle Kessler suture.
OK, what else you're going to repair? So I will. We're going to get I guess we better this year, isn't it? Yeah, repaired the sheet and I don't know, I'm just before that. At the moment, we will repair the tendon of the yard to prevent the boys thinking how to take care of the police as well, especially the egawa and the airport police.
I have to repair them if they are completely damaged. I will repair them with the EPDS tendon. All right to you're going to reconstruct it. I'm going to reconstruct it. So you're done the repair. OK what position you want to kick the hand? So there are two basically the reflections you are or are not involved, you are in the now repaired and then just no, and how are you going to keep the I'm going to keep it in the Edinburgh position and blocking the extension, and I didn't position that is the extension at the pipe, at the inter-provincial joint and the flexion at the MCP joint to allow for the maximum extent of the collaterals maximum stretch of the collaterals.
OK all right. This is basically you're keeping it in that position where you are going to slap, tuberosity or Walla. So I will put the slap dorsally to start with and but I will Institute a range of movement that will be Cooperative Extension into hand in hand. What is the principle of hand therapy? So the principle of hand therapy is to get active extension as soon as possible, and then the passive collection can be by the splint assisted or by the patient assisted.
So the idea is to get an active wrist extension in case of flexor tendon repair and the patient or the splint assisted the passive flexion. Look, you are to prevent the stretching of tendon. Basically, isn't it always stretching? Yeah what can be the complications of the tendon repair? So there could be various complications like adhesions of the tendon or there could be real rupture of the tendon.
There could be cotija effect. There could be contractures and repair failure, as I already said. What is it or is that? So whenever one of the tendon is repaired or as a result of trauma, it heals in a more contracted position in then, while making the grip, that finger will contact the palm first and lead to the inefficiency of contraction of the tendon should be tied to get Corica effect.
So the tendon, which is repaired that will be more contracted and it will contact the pump first and arm first, isn't it? OK, that's fine. You're done well, ok? Just needs to be tidying up. So first thing when you are, I told you last time also when you see the like photographs like this, ok? Why don't you tell? Just do I do tell you?
You say that right? The little finger is kept an attitude of extension. I think there might be tendon injury. You are actually giving a lot of information to somebody and making yourself clear by just saying few words like this, rather than just saying it is like the static scar. OK, then your answer this assessing tendon injuries first inspection.
OK they'll be abnormal push like you can see in this case, you assess the acute contraction of tendon that you demonstrate and pursue tenodesis that also you told me egawa tendon plays. You are quite good, but you put it in a much easier way. I think like at that level of the wrist, the FDA, the same playing and are in this. So this attitude of principles of tendon surgery is first automated technique, it can be done under anesthesia or wide awake.
First, this repair could give 4 to six core sutures. OK, and all around you epicondylitis sutures. All right. Repair the sheet, OK, and place the tendon in a position of protection and referred to hand physiotherapy, which actually there are various protocols. I don't know, but basically they allow the flexion but prevent the extension of the stretching of the tendon.
All right. Complications, you can say there are general complications like infection, but basically complications are adhesions and rupture. OK, now Quadriga effect is specific to the flexor tendon when it is suture tightened with the fingertip register from before the other fingers. So you got a rough injury of your ring finger and you put it in tight with rich finger before other fingers.
All right. OK so. And then little plus sign, you know, the about that, isn't it? People, when you know, when the repair is not good, the poles get transmitted to land because then it paradoxically extended. What you'll get there, but they are much better. I just try to refine your language, not technical, you know, quite a bit.
You added the organization of knowledge is good, but the wording is wording is what you are lacking. So what do you see? Is the language, you know? Yeah OK. All right, guys. OK, thank you. Well, this is the.
The principle of tendon repair is Kessler suture circumferential centimeter repair of sheet and mobilization. All right. So who is going next? Survival analysis? OK I will do a survival analysis using either a kaplan-meier code or using an actuarial method.
So actual method normal is done at a fixed intervals and the kaplan-meier code analysis is done at the time of failure. For example, in orthopedics, it is done at the time of revision. For example, if we are talking about total hip replacement or a knee replacement and so this is so I would take here is a kaplan-meier code, for an example.
So it is part and it's a time which one you prefer. You're doing like using a table. What are you going to do like couple kaplan-meier? I would prefer to use an kaplan-meier. Why I say this is the number one, the reason is I can analyze at the time of failure instead of doing it at a fix, it ensures there are pros and cons on both sides. But I would prefer to use this one because I can analyze at the time of failure, because that is a significant event.
If I say that's the one thing under the kaplan-meier code has got various characteristics and also it allows variable dates of entry and then follow up as well. And so I can compare that to implant performances at the same time. Uh, OK. OK, tell me here, so what's that?
What's that? So this is the. This is the survival analysis table. No, I'm not sure. Yes, you are right. That's what happens is a bit small. I'm just zooming in. I'm really sorry. So yeah, I can see the time interval on my left side and I can see no at risk.
And so I can see the number of events. I think that denoted that denotes the failure. And also the survival is calculated here. And also, we are getting the confidence interval accordingly based on the sample population. So it's. So the confidence interval mean it's a 2 standard error of the mean either side of the sample mean. So if you say 95% confidence interval, that means that true population mean lies within the we are 98% confident that true population mean lies within that range.
And usually the confidence band, normally in a venue, draw a cap and my call is become wider. If if the sample size becomes narrower or a smaller on the side, each time when the failure happens, we do some mathematical calculations. So we do that number at risk and then we see from that we will calculate a percentage of failure rate from the percentage of failure rate.
We calculate percentage of success rate and the cumulative probability of failure. And from there we will get the probability of survival. So then once we get the probability of survival, we put it in the vertical axis. And then the horizontal axis we will draw over time. So then we will get the cap on medical. OK OK. So, yeah, tell me what you see here in this, yeah, so this is a nicely plotted the kaplan-meier code is, I think, the time against the probability of survival, the central line, which is I'm interested in to describe to start with, in which the vertical dip, which indicates the time of failure here this rubicon, the small vertical blips at the center of the horizontal line, which indicates is a right censoring.
So the right censoring means it's a withdrawal spike is the loss to if the patient is lost to follow up or a death. And these are all the right censoring and say and also I can see the confidence band is getting widened when the time goes up. And that means that the sample size is getting replaced. And so my left side of my code, the numbers are at risk.
I have and the right set of my code, the number of failures. And as well as the number of the towers. OK, so, OK, so which which was this line, you see my arrow? Yeah, I can see that the daughter, the dotted lines at this indicate the confidence band. OK so, OK, so what do you think you did? I think I was trying to give some structure and you did well, but but there is I will tell you how to answer these questions.
Yeah so if I examine you, I will pass you. I'll give you six. Yeah but I will tell you now how you can get eight easily with the same information you have. Yeah, you're not at anything. Just polishing your answer. OK, so let's start again. Yeah OK, so this is OK. Survival analysis, OK, so definition, so the outcome of intervention is plotted over time, so we didn't mention the intervention definition, which is the starting point of your answer.
So start your answer with your definition. So what survival analysis is an outcome of if intervention is plotted over time, which allows for variable date for that of entry and different lengths of follow up? Yeah OK, so I can like do for over 2 years, five years, 10 years, and I can measure any loss of full above two years, five years, lots of follow up of patients.
So I started with 100 end of this. My research with 80 patients, I have 20 patients lost of follow up. I still can do a survivor. Analysis for the procedure is like a new head, a new procedures, whatever. Yeah, OK, how you can do that? OK there is a low equatorial life table, which is mentioned here.
Yeah, and time of failure. Let's give you definitions. So instead of saying equatorial life table method, I will say definition is a fixed intervals and times of failure. So fixed intervals represent equatorial life. Table method yeah, OK. And there is a time for failure which kaplan-meier. Yeah OK. OK how to construct a life table for joint replacement for an example.
OK the end points, you have to be defined. OK, which is usually revision, so if you your example is a new prostheses for hip replacement, the endpoint to be defined here is the revision. Yeah, OK. Yeah and the number of joint followed of joint being followed and the number of failures are determined for each year after operation. So as I told you, we're doing for up two years, five years, 10 years, and we'll measure the failure of the which is by definition, here is the revision.
Yeah OK. And for each time period, number of patients at risk, like painful hep, maybe infection, all the things and the number of failure and the number of withdrawals you have to be recorded as well. So how many patients like has been withdrawn for sometimes you're also full of the patient is very happy. That couldn't be counted as a failure or revision because the patient maybe didn't attend the follow up clinic because it's very happy, very impressed.
And he thinks that no need to come to see the doctor. Yeah, OK. Yeah so then this is the kaplan-meier graph. So when you see that the way I'd like you to answer no one, it's definition outcome of intervention plotted over time the X time. So now you, you will like identify everything. So let's start with the X-axis and y-axis.
The line in the middle, the two dotted lines and after that describe the other things you started with the sensors, with the steps. Yeah so you started from the end and then you came back to the beginning. So you mentioned everything. I am very pleased with your answer, but now this is better if you extra mark with the same information with the same knowledge.
Yeah OK, so this is the definition defined, defined first. I see. Except whatever. OK, I see like this is the kaplan-meier is the outcome of intervention over time. Always remember this definition. Yeah, OK, it's x, which is the time elapses. The y represents the percentage of the population surviving.
So how many patients now to the 50? So by the time the number decreased? Is it ok? Does it make sense? Yeah Yeah. I thought of y axis, they say, the probability of survival on the vertical axis, so I'm a bit confused here. Is it outcome of intervention?
Does it mean like the does it denote the probability of survival? Yes, the same thing. So the number of yeah, Yeah. And there is OK, the dotted lines. This is the confidence interval you mentioned that. So the dotted lines are confidence interval and there is and now you will describe what's in between. OK, so increased over time due to decrease the number of patients, yeah, less reliable data towards the right, which is the right side of the blood to represent best and worst case scenario.
And the other, which ones our dotted line assume all lost fill up it and the law assumes they all failed. Important to compare between the tuberosity can tell difference if there is no overlap. So, OK, that's really nice. Yeah, thank you. Yeah and there is a sense of the lost patients I didn't find was the little mark.
Subjects that are uncooperative or refuse to remain in study. So that it shouldn't be considered failure. Yeah, OK. Don't experience, event or die. Maybe die from heart attack or anything. Not from tuberosity. Yeah so before the end of the study, or they lost to follow up, they is the most important sentence here.
They don't count that as a failure. Yeah, OK. So I will try it again. So this is kaplan-meier number two definition. Number 3 is X and yz four. Four OK. Number four the dotted lines number five. Something in between. OK and the bigger one and then the smaller one.
Yeah, which is a small sensor. Yeah is that clear? Yeah, absolutely. Thank you so much. That's so answer. So you have the knowledge, but the way you've answered and do not miss anything if you have a technique of 4 and 4 to answer these questions. Yeah so sorry, can I ask a question?
The vertical line is that what? What shows that? Or is it the is a transverse line which goes beyond? No, the transfers line is the time. Mm-hmm And on the main, I mean, the main axis is the no. So with time, the number is increased and you see the confidence interval here between the two dotted lines become widen because you lost a follow up due to like many things.
No already like loss of follow up, maybe revisions. Maybe patient die. If if it's a loss of follow up, will it be a vertical line or a transversal? What you mean here? No, here, here. You know, This is this is like, this is no, this is a revision. So this is the steps is the revision. The census is a long lost follow up.
It is a small sensor here. That one, ok? That's fine. Yeah, that's right. Yeah the steps is the revisions, and the one step is the revision and the line is essential. Yeah, exactly. OK, Thanks.
OK so who is the next?
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