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So. Ok, this talk is on carpal biomechanics. Er, and what Aaron wanted me to talk about was about Slack and snack, which is um mechanics going wrong. But to understand Slack and snack, you've gotta have a bit of a knowledge of what's going right. Has there been a talk on carpal instabilities of any sort? Uh No, I don't believe so. Cool. Ok, so I'm not gonna talk about carpal instabilities. It's too much for you to take it at four o'clock on a Thursday afternoon, but we can start with um some learning outcomes what we are going to talk about. So, you know, at the very basic form, someone was asked in the exam, ok, four corner fusion, one of the four corners. And Aaron did mention this earlier this afternoon. He said, well, the lunate is one of them. Well, that's fine, but it, it'd be quite embarrassing in an in fr CS al exam not to be able to explain which bone goes where and what bone you might fuse to another bone in some sort of carpal limited in intercarpal fusion. So we're gonna just revise the anatomy, talk about normal biomechanics briefly and then talk about some common pathologies, obviously. Slack and snack is the remit and then some treatment options and a little bit about those various fusions just so that you feel educated. If you get some of that, that'll be a great outcome. What level are people in general are you pre examined? Mm. Mhm. We've got, uh, uh, trainees all the way from ST three to people who are pre exam and, yeah. Good. Ok. And so I'm presuming that some of the knowledge is very basic and some is quite basic. Um but no one will be hand fellowship er level. So that's good. Ok, fine. So have a look at the X ray and anybody call out some of the pathologies that you can see when you look at it in particular in the carpus, uh the severe uh radiocaps uh arthritis. Um that's a good start to the base of thumb arthritis. So um yeah, with the, the junction of the base of the mass carpal and the trapezium. Yeah. So basically with thumb arthritis and other than that now, very welcome to have a go uh in no sense of anybody else. I th the lunate, I've, I've not seen the lunate in, in that place before, so the lunate isn't under the capitate. Um And I don't know what that would look like on a lateral, but so I is the lunate in the wrong place or actually is the capitate in the wrong place. That's the question, I'm gonna say the lunates in the wrong place cos the cafetrate is still under the um third master car. It is. But what's happened is that the lunate is sitting on the distal radius in the lunate fossa. So something's happened in the mid carpal joint because like you said, the capitate is in the right place in relation to CMC and the lunate is in the right place in relation to distal radius. So what's happened is the entire distal carpal row has shifted radially and approximately and there is gross capitol arthritis. The bit that everyone misses is the chondrocalcinosis in the T FCC, which might suggest that the underlying problem here is a crystal arthropathy and mia mentioned gout uric acid crystals, but this is much commoner pyrophosphate deposition disease. And if you look for it, you'll see it in other joints as well. People quite enjoy the knee, don't they? They often look at the meniscus to see CPPD in the meniscus. The thing about where and wear particles is that wear can be in an implant, adhesive, abrasive, et cetera. But one of the wear patterns that we see is third body wear. Now, if you've got a load of crystals floating around your joint, it's not surprising but like a stone in the shoe to find that the joint wears out prematurely, the cartilage is full of crystals. It becomes very non compliant, not very plump and watery but quite stiff and fragile and brittle. So you're taking a stiff, fragile and brittle cartilage and you're adding in some crystals which are gonna grind away like a sandpaper at the joint. So this primary problem is probably a CPPD. And then as a result, the rest of the wrist is degenerated. And you can see here as Nick said, radius, scaffold arthritis with an erosion, distal radius, midcarpal capitol lunate arthritis with proximal migration and radial migration of the capitate, basal thumb joints gone. But the underlying cause might be CPPD. So keep an eye out for these things when you're looking at x-rays. Excellent. Well, Nick, I hope everything else is still engaged. So the next question is what symptoms did this patient have when they turned up in the hand clinic last week, I'll describe the X ray where you're thinking about what symptoms they might have had. Again, you can see pyrophosphate deposition or calcification in the T FCC just distal to the ulnar. You can see calcification in the arteries, both the ulnar and radial arches. You can see uh calcification dorsal to the wrist. If you're really cute, you might see that the lunate is extended and the midcarpal joints flexed. So this is a risk in trouble. It looks like quad degen have changed, some risk collapse, some calcification and some paraprost deposition. Any thoughts as to what symptoms the patient presented with just taking a guess, maybe a onset pain and swelling in the wrist. Yep. So they might have, but actually that wasn't the case and this person was being seen for a completely separate problem and had an X ray, uh, some time ago and this showed this some time ago and the pre the presentation of the handling, it was actually more about durans and this was completely symptom free. And what's bizarre about the wrist is that some people with really rotten looking x-rays have very minimal symptoms. So when we're thinking about treatments for wrist problems, we do have to consider how much of an issue it is for the patient. And if it's not an issue, we'll leave it alone. So we're not treating x-rays, even if the x rays look rotten, sometimes the wrist is quite forgiving in the symptoms. It gives to patients in comparison with a weight bearing lower limb joint. So surprisingly, you might find they've got very wrong with them. So treatment should be based very much on the symptoms rather than the imaging. Here we are, this is a normal wrist. Now, this is just demonstrating the bones of the wrist. So you can see the letters scaphoid, lunate, triquetrum, the proximal carpal row. And Aaron mentioned that when you do a proximal row, carpectomy, you'll take out these three bones, a distal carpal road. You can see the H and the C for the hamate and the capitate on this X ray. You can just about see the Pisa form superimposed under the trip and then beyond the scaphoid, you can see the two Ts which form the S tt joint, the trapezium which is under the thumb and the trapezoid which is under the second metacarpal. People say the trapezium's under the thumb. The trapezoid is inside. It doesn't really matter. It's important to be able to recognize the, the carpal bones and name them. I know this is very basic but it would be embarrassing not to be able to do this in an Fr CS all. Now glu like the shens lying around the hip. Galua talks about the lines around the wrist which demonstrate normal alignment. So the the lines are proximal end of the proximal carpal row which is in blue, the distal end of the proximal carpal row, which is in red and the proximal end of the distal carpal row which is in yellow. And these three lines give you a suggestion as to what's going on in the wrist. A break in these lines would suggest some pathology. Galla lines have a look at this lateral X ray and see if you can work out what might be going on. The story was a patient had a fall and outstretched hand. And when they present to the fracture clinic, that wrist is quite swollen and they have tenderness dorsally on the ulnar side. Has anyone seen this radiographic sign before there fracture on? Mhm in the fo bone chip fracture So the where are you looking at Neil on the dorsum surface? Yeah. Yeah. There. Yeah. Yeah. And what do you think this black bed is just distal to it? Mhm No, soft tissue shadow. Not sure if that was the elbow. And you saw that around the elbow in the context of a kid's fracture, what you call it? Yeah, a fat pad. So this is, this is probably a joint effusion. So it's probably a bit of bleeding association with a a wrist injury. Um This is also called the pooping duck sign. Some people who have heard of this, it doesn't seem to be on the English curriculum. But colleagues who have trained in India seem to bring this up as a as a common finding. And the pooping duck is just a dorsal avulsion off the TRM. The TRM is the most ulnar placed bone in the proximal carpal row uh on the uh and the reason for that avulsion is this. So the dorsal extrinsic ligaments have their apex on the TRM. So a wrist sprain which sprains the ligaments can either rupture the ligaments which should then heal or pull off a chip of bone from the dorsal trich. So this is just a reminder of the dorsal extrinsic ligaments of the wrist. The apex of those ligaments is the re they form a triangle ligament complex. So the first row is from the radius to the trich. And the second row is from the TriCor back to the distal carpal row. Two names you need to remember are the dorsal radiocarpal ligaments from the radius to the trich and the dorsal intercarpal ligaments from the TRM back to the scaffold and the, and the S TT joint. So the D RC and the D IC, these are the dorsal extrinsic ligaments and most commonly injured by a wrist sprain. We use those ligaments or the line of those fibers for a ligament, sparing capsulotomy Berger, who's an American wrist surgeon described this as a way of getting into the dorsum of the wrist by running your knife along the line of those fibers. So in other words, make a chevron shaped cut with the apex of your cut at the trpm and flap, the capsule back towards the radial side of the wrist parallel with the dorsoradial carpal and the dorsal intercarpal ligaments. And the photograph on the right is taken from a video showing the blue dots here, the distal radius, the bones here are the proximal carpal row, the scaphoid under the arrow at the moment and lunates just there with the scapholunate ligament between the two, the tendons have been reflected to the ulnar side. And then you can see the distal carpal row just here. The ligaments been reflected to the left to the radial side. So this is a berger capsuling a way of entering the wrist from the, from the dorsum. Berger describes what you can say there on the border of the radius. If you do that, you need to use suture anus to stick it back on. Otherwise you can disrepair the ligament, uh the capsule er incision was just interrupted, absorbable sutures so that we use the dorsal extrinsic ligaments as a way into the dorsum of the wrist. And we'll talk about that later on, the berger capsulotomy on the front, the ex the extrinsic ligaments are formed off the radius and the ulnar and the apex of the attachment is the capitate. Now, the reason for this is because in the past, the wrist was a weight bearing organ or the hand was we used to walk on our palms and the wrist was usually held in full extension which is a bit like the foot. And so you need to have a volar wrist complex which can extend into full extension, but also be functional with the wrist in neutral. So by having ligaments attaching from radius and ulna to the capitate, there is a possible uh extension and the ligaments can open up like a concertina on the front side. The problem with this system is it leaves a, a space or a weakness around the lunate because although there are ligaments from the radius to the lunate and ligaments from the radius to the capitate, there are no ligaments that, that support the two. And so as the carpal rows separate in extension, that creates a weakness on the volar capsule. I've written that drawn that in red but that is the space of Coie which is a weakness through which the lunate can dislocate. So the ligaments you need to learn on the volar side of the wrist are the radioscaphocapitate ligaments. The R se which run for the radial styloid across the scaphoid, in fact, grooving the scaphoid and the R se ligament is the reason the scaphoid has its scaphoid posi er er form. So the scaffold is kind of boat shaped. Hence the name from Greek or shaped like a cashew nut around the R se ligament that ligament, the re attaches on capitate, the ulnar capitate ligament runs from ulnar to that same point. The luna itself is stabilized purely by long and short range lunate ligaments and some ulnar lunate ligaments. But these are separate from the RSC and the UC. And so there is a potential for a lunate dislocation. So in other words, the diagnosis in this X ray is a lunate dislocation. You can see the lunate is dislocated here in front of the distal radioulnar joint. Here there's var to the wrist itself. And the reason it happens is a weakness in the volar wrist capsule complex. This space of Proia, this red line in between the two rows of ligaments between the proximal and distal carpal bones. The third set of ligaments to consider in wrist biomechanics is the intrinsic ligaments. Everyone's heard of the proximal carpal row the scapholunate intra ligament, the sl io and the lunotriquetral ligament. But there are also ligaments binding the distal carpal row together the er trapezia trapezoid, the capito trapezoid and the capito hamate, you can see them all there. Um So intrinsic ligaments, now, these are not really ligaments in the, in the same way that the extrinsic are, they're more like fiber cartilage. And if you look at this cross section of the scapholunate ligament with the scaphoid removed, you can see that there's a almost D shaped band that runs from lunate to scaphoid and it's mo mostly made of fiber cartilage very difficult to repair and quite commonly torn through hyperextension of the wrist. We think about the proximal carpal row as being bound together like the front row of a scrum. Er the three bones are held together by these fibrous uh fibrocartilaginous ligaments, the scapholunate and lunar triquetral ligaments, the hooker, the person in the middle with black hair and the headband is bound only by the other two and has almost no control of what happens to them at all. So, the scaphoid is constantly trying to put a flexion force on the lunate. The scaphoid is a torque converter. So if you were to push on your scaphoid tuberosity in your wrist, you'll have to work on this one at home on your own. If you put your thumb where your scaphoid tuberosity should be just at the distal end of the forearm underneath the flexor carpi radius tendon. If you move your wrist into ulnar deviation, the scaphoid tubercle disappears because the scaphoid has gone into full extension. As you move your scaphoid or your wrist into radial deviation, the scaphoid tubercle becomes quite prominent because in radial deviation of the wrist, the scaphoid has gone into flexion. I'll describe that again. So you can try it, put your thumb on the scaphoid tubercle, which is at the distal palmar crease just underneath flexor, carpi, radialis tendon, move your wrist into ulnar deviation and you'll feel that the scaffold tubercle has become quite difficult to feel as you radially deviate your hand, the scaphoid tubercle becomes more prominent as the scaffold goes into flexion. The scaffold is a torque converter converting the ulnar to radial deviation of the wrist into extension to flexion of the scaffold. Are there any questions on that before we move on? So the scaphoid is constantly placing a flexion torque on the lunate and the trich TRM is constantly placing an extension torque on the lunate a bit like the front row of the scrum. If a linkage between one of those two bones is broken, then the lunate, which is also called the intercalated segment, the lunate will move with the other bone. So in a carpal instability pattern, if the scapholunate ligament is ruptured, the lunate will extend with the trich. Here's a normal wrist x-ray seen from the lateral view taken from a radiological website with dotted lines around the bones to make them easier to see. So we can see the lunate, which is marked as D we can see lister tubercle on the distal radius which is marked as E and we can see the capitate, which is happily ac A points to the distal pulse skateboard and B is pointing to the pisiform. When we're looking at wrist collapse patterns, we're looking at the alignment between the scaphoid, the lunate and the capitate. The most useful thing ironically is the capitol lunate angle. Everyone would like to quote the scapholunate angle but the lunate should face straight up. In other words, the lunar should face in the same plane as the distal radius and the carpus, the capital lunar angle should be zero, but it can be between 30 minus 30 degrees. Although ideally, it should be pretty much straight. And the range we put for here for the teaching is mi minus 15 to plus 15 of extension or flexion about that axis. So the two red lines which the long axis of the L Kaza should line up pretty much straight and the degree of midcarpal flexion collapse equates to the degree of wrist collapse. It wouldn't be immediately obvious. But with a dorsal intercalated segment instability, with a lunate tilted dorsally, the midcarpal joint will flex and it's the flexion of the midcarpal joint which causes the problem that the patients will experience rather than a problem with the sca o. So the the other thing we should be looking at is the scapholunar angle which is in yellow. The scaper lunar angle is an angle between the long axis through the scaphoid and the long axis of the lunate. Here, we can see it looks around about 60 degrees and the normal range is between 3060. If the scaphoid flexes any more than 60 degrees, this would suggest there was a scapholunate ligament rupture that might be associated with the lunate extension as well. And if the lunate goes into extension, the midcarpal joint will then go into flexion. So a wrist collapse pattern with a scapholunate rupture would be a flexed scaphoid, probably more than 60 degrees and maybe up to 90 degrees scapholunate flexion with a midcarpal flexion collapse. A dorsal intercalated segment instability, flexion of the midcarpal joint. Are there any questions on that before we move on? Can everybody hear at the moment? Yep. Sounds like on the chat, there's some people experiencing difficulty, Chrissy sort of signed, signed back in, but it's got a, a warning sign next to her. Nick. Can you hear? Hey, boss. Yeah, I can hear. I've, I've too had to sort of log, log, log out, log in a couple of times. I think there's something weird where the slides don't move on, but it's fairly quickly rectified. So it doesn't usually affect things too much when you turn it off, turn it on. Again. So is it working for you? Yeah. Yeah, it's working for me. This is tedious, isn't it? We should be on zoom. OK. So this is a carpal collapse pattern. This shows what dizzy looks like dorsal intercalated segment instability. So your lunate has gone into extension and the midcarpal capitol lunate joint is flexed. I've got an X ray showing scapular gapping on the apa lateral showing lunate extension and midcarpal flexion and act confirming that the problem with the dizzy collapse is the lunate has almost fully extended in the radiolunate joint, the joint between the radius and the lunate. And so there's almost no further lunate extension possible, which means that the patient can't extend their wrist at the radiolunate joint. But the mid carpal joint develops a fixed flexion contracture of the volar capsule. And so the midcarpal joint can't extend either. And for this reason, a dizzy causes difficulty in wrist extension, but the patient can often flex their wrist quite well. Unfortunately, most function of the hand is with the wrist and extension. So a dizzy can cause quite a significant functional loss due to stiffness of the wrist. This is the alternative, this is where the lunate has tilted forwards and the intercalated segment of the lunate is called a volar intercalated segment instability or a Visy. If you look at the ap, you can see the massive overlap between the proximal and distal carpal rows, which is almost pathognomonic of a Visy. And if you look at the lateral, you can see that the lunate is tilted forwards, you can see the lunate is almost colinear with the scaphoid. And so the scapholunate angle is now pretty much straight or zero, much less than the 30 degrees that you'd accept. But the mid carpal joint between the lunate and capitate is highly extended. Yeah, it still getting quite a lot of concern on the feedback. Can people still hear? I can still hear but perhaps other people can't. It's very strange, isn't it? I'm not sure we had so much problem with metal before. It's a very unstable platform. So we were just discussing Visy. Now, the problem with dizzy this one before was that the patient couldn't extend the wrist because of a fixed flexion deformity in the mid carpal joint and a hyperextension deformity of the radiocarpal joint. So there's no further radiolunate extension and no possible Capitol Lunar Extension because of soft tissue tethering. A Visy will allow good extension because the lunate is well flexed. And so there's plenty of radiolunate extension to be had. Even if the midcarpal joints a bit stiff in flexion, the patient here can't flex the wrist very well and flexion is rarely a problem. And so people with a Vizi often don't have major issues, certainly in terms of functional loss. And this is often either picked up asymptomatically picked up because of part of a non dissociative instability pattern or picked up just purely because of an X ray so busy may not cause issues. These are the two common collapse patterns seen. And that's the only thing I wanna say about carpal instability. Why does the carpal collapse cause cartilage loss? Well, the classic model is two spoons in the cutlery drawer. If you twist one of the spoons a adjacent to the other, you then develop a noncongruent oval joint. This is a bit like flexing the scaphoid in the radius fossa of the uh sorry, the scaphoid fossa of the radius and as soon as the scaphoid is flexed, you'll get point loading and also the instability of the carpal problem will cause shear forces across this. And not only do you have increasing forces over certain points of the joint, you also have a shear force applied across those. And you can imagine that would cause cartilage loss fairly quickly. So the assumption is that the scaphoid flexion coupled with instability or laxity in the joint will cause shear forces and point loading leading to secondary radio sccap arthritis. But the wrist is very benign and unpredictable. So this person who was young and female and had asymptomatic gapping between the scaphoid and luna on her X ray had no symptoms and is under follow up review, but no intervention is required. These guys in writing. Now, 21 years ago, identified people with isolated ligament injury and arthroscopic them as just a series of 11 people, but they arthroscope them over a period of seven years and found that there was no significant development of painful arthritis. People were not necessarily er functioning normally and there was pain and some functional limitation, but there was no rapid progression to slack wrist. So the assumption a bit scaphoid flexion leads to point loading and shear forces with chondral loss is not always borne out and not all patients with scapholunate gapping inevitably develop osteoarthritis. Another question that would be quite embarrassing to be asked and not to be able to answer in the ar exam would be what is osteoarthritis. So we'll think about that for a minute and I'll invite volunteers to come up with a one sentence definition for osteoarthritis. Anyone free to speak up. And the first answer is the easiest because you just get free reign. Uh Mister Johnson. I can attempt that one M George, the moderator. Hello, George. Hi. Um Is this for osteoarthritis then? Sorry. My signals are very good. So, I'd say it's a um, a chronic degenerative disease affecting like, oh, can you hear me on and off? Keep going on and off. So, a a chronic degenerative disease affecting synovial joints, um causing um, cartilage loss associated with characteristic radiological findings which are, and then I would list my for loss of joint space. Um Subcontrol cysts and sclerosis. Fantastic. There we go. So, what's really nice is to have an answer which is complete rounded and has a beginning, a middle and an end. Is there anything you want to add into that? I think if you use clever words like end stage arthropathy, but more chondral dysregulation, you're gonna have these guys on the other side of the examination table going. What? So primary osteoarthritis actually an active condition of dysregulation of cartilage turnover. And I was rather hoping that George being the M MP man would bring this up. Um But a lot of guys haven't even heard of an M MP. An M MP is a matrix metalloproteinase. A matrix degrading enzyme turnover enzyme er and the inhibitor of a matrix metalloproteinase is called a TIMP or a tissue inhibitor of metalloproteinases. If you look at samples of cartilage taken from people with osteoarthritis, particularly primary osteo, you will find that they have massively up regulated collagenase activity and dysregulation of in inhibition. In other words, the turnover processes for cartilage, uh remodeling goes wrong. So primary osteo which is inherited er is a chondral dysregulation, which as George said, absolutely leads to chondral loss. And then the classical signs subsequently, it's a disorder of extracellular matrix turnover particularly in the cartilage. Is it a degenerative condition? Depends on the definition definition of degenerative. There is a definite difference between primary osteo and age related changes in cartilage which you can read about osteo or chondral loss. Cos osteoarthritis really is a final common pathway of chondral loss in the joint can also be secondary to loads of other things. We mentioned wear pyrophosphate crystal arthropathy and wear particles, but also joint instability, which we just talked about point loading, shear forces across an unstable joint, uh fracture or other injury, chronic inflammation or infection all leads to chondral loss. Uh We all talk about secondary arthritis. That's the sort of thing we're talking about the final common pathway. It is the joint becomes painful and the bearing surface has lost its cartilage coat leading to pain, stiffness, deformity and loss of function. But just think on questions like that for Survivor practice around the definition as George gave. For what common things are. For example, what is tendinopathy or enthesopathy? What defines Xy and Z we particles or just the the process of wear, et cetera, which joints do to consider in osteoarthritis in the wrist. Well, you can see here, I've put some boxes around these. So we've got the S TT joint between the scaphoid, the trapezium and the trapezoid distally. That's the top left box. Then we have the cap lula, the midcarpal joint. Mira mentioned in rheumatoid that the mid carpal joint can be affected. And often if the patient has a midcarpal end stage arthropathy, but the remainder of the wrist is normal, that may well suggest an inflammatory arthropathy. So midcarpal is often affected preferentially by inflammatory arthritis. The radios scaphoid joint is often affected by scapholunar advanced collapse or slack wrist. The radiolunate joint rarely affected by any process except for end stage. And the ulnar carpal joint is affected, usually because of positive ulnar variants and ulnar carpal impaction most commonly due to distal radius fracture, radial shortening and secondary positive ulnar variants. But people can be born with a long ulnar and so ulnar carpal impaction can also be primary. Finally, the distal radial ulnar joint. So when we think about wrist arthritis, we're thinking about several classical joints and the paper which described slack looked at those various joints to look at frequency of arthritic change. So here we are, this was the original paper talking about scapholunate advanced collapse or Slack. Kurt Watson and Frederick ballet Watson and ballet's paper. And it is worth getting a copy of this. It's probably available free. Now, general hand surgery, 1984 4000 wrist X ray films were reviewed to establish the pattern of sequential changes in degenerative wrist arthritis. After eliminating everything else, we studied 210 cases of degenerative arthritis. The commonest pattern being arthritis between the scaphoid lunate and radius and they call this slack. So here we are, this is the picture. They took 4000 x rays. They put numbers on all over the bones in the wrist and they identified a subset of 210 osteoarthritic of which 100 and 20 had the slack pattern area. One being the area between the scaphoid and lunate area. Two being the lunate sorry, the scaphoid fossa one rasca radios Starlight two between the scaphoid and the radius and three, the midcarpal joint between the capitate and the lunate S tt counted for about 1/6 only 3% were involved in the remaining joints. So, arthritis elsewhere is relatively rare radiographically. So here's the from the paper stage, one scapular advanced collapse, the scaffold starts to flex the distal pole of the scaphoid starts to cause arthritis against the rasty lode. Just the radio style. Quite an early stage. A patient may experience radio sided wrist pain. But if you look to take an X, the only changes will be the tip of the star and the distal pole of the scaphoid stage. One slow stage two slack, the scapholunate ligament separates and the scaphoid begins to move away. There is a diastasis. A Terry Thomas or Madonna sign the gap between the scapholunate. The entire scaphoid fossa of the distal radius becomes arthritic scaphoid flexes. So on the lateral view of the X ray, you'll see midcarpal flexion, you'll see a dizzy a dorsal interclass segment as the lunate starts to extend with the triquetrum, you'll see scaphoid flexion and you'll see on the AP as you can see here, radio sccap, arthritis, midcarpal joints preserved. You can see all around the capitate that the joint spaces are still visible. But in stage three, the capital lunate joint was zone three. In the Watson ballet paper, the midcarpal joint becomes arthritic So this is a a secondary effect of slack and unlike a midcarpal joint, which is affected, primarily due to inflammatory arthritis. This is definitely due to er progressive slack wrist, there remains a scapholunate gap. The capitate migrates approximately and radially into that gap as we saw in the original x-ray right at the start and you develop secondary capitol arthritis. So the difference between stage two and stage three, slack is the presence of midcarpal osteoarthritis. And that has implications for treatment options. The other pattern of arthritis around the wrist relates to or around the scaphoid relates to scaphoid non union. And so here we are, Kurt Watson, once again with a different group of authors here, looking at patients who are symptomatic scaphoid non unions without surgical treatment leading to secondary arthritis. And you can see here in the abstract non units of four years duration or more. Three quarters of patients had radiocaps arthritis and for patients of nine years or more, 60% of patients had midcarpal change. In other words, untreated scaphoid nonunion leads to secondary arthritis. So what they looked at was signs for instability including the angle between the scaphoid and I lunate, er the dizzy. In other words, the midcarpal flexion angle how displaced the fragments of scaphoid nonunion were and whether there was any sign of scapholunate gapping, they looked at the duration of non union, goodness knows how they chose less than a year, 1 to 4 or 5 to 40 years, presumably pragmatic. What they found was the increasing occurrence of instability, increased the risk of arthritis. So for example, if you compare displacement of the scaphoid fracture where there was no displacement, there was less arthritis where there was more displacement, there was more arthritis and the same for a dizzy collapse where there was evidence for wrist instability through a dizzy, there was a three fold high rate of arthritis. So there's something about not the scaphoid non union, but the associated instability which causes the problem. And this goes back to what we talked about the spoons and the cutlery drawer. It's the instability, the lack of congruence and the sheer forces across a non congruent joint that lead to secondary arthritis. The conclusions of the snack paper were as the abstract arthritis in the rasca joint in three quarters over four years and midcarpal arthritis in almost two thirds by nine years, the degenerative patterns were seen to occur relatively early after establishing non union, especially where the wrist was unstable. And ironically, the wrist instability got worse, although you'd think it would get better as the wrist became stiffer. So we've talked about stage 1 to 3 slack, stage one radio styli only stage two entire radios fossa and stage three, mid carpal joint. But here we are stage four slack or snack, which was pancarpal. In other words, the radiolunate joint, the joint between the radius and the lunate proximal end was also uh arthritic. This is a relatively late edition was not actually part of the original classification and relatively rarely seen. So when you see pan carpal arthritis, you realize there are very few options for surgical reconstruction. But this is a relatively rare finding back to sl this paper found that not all patients with slack changes on X ray had evidence for or sorry, had significant pain and therefore required treatment. And this was looking at asymptomatic slack as a the the second case we discussed 1st, 1st in the lecture, 25 patients, 30 wrists and x rays of slack or scapholunar advanced collapsed, 22 patients had no pain. So we don't treat the x-ray even if we recognize collapsed patterns on the X ray, we treat the symptoms of the X ray er may be associated with. And the conclusion of this paper was we believe there are some patients especially older and lower demand in whom X ray evidence of arthritis and the clinical findings did not correlate in these circumstances. Surgical intervention for treatment of arthritis may not be warranted and I would say is not warranted. So what are your treatment options for? As for any arthritic joint, we're looking at pain relief. The primary outcome of treatment for arthritic wrist is pain relief and sometimes that comes at the cost of loss of movement. So we can try non operative treatments, we can try analgesia splintage and we can try an injection. And the picture on the right shows X marks the spot which is the soft spot just distal to the distal radius, which is where you put your injection needle in. This is in between the extensor tendons of E PL and EDC. So in other words, the extensor to the thumb and the extensor to the index finger. And if you feel on the back of your wrist, because you'll be able to feel the soft spot just at that point, distal to the distal radius where the injection goes in or where you might aspirate the wrist. If you were aspirating for possible septic arthritis, this should all be common, commonplace knowledge and you should all feel familiar with that injection aspiration point in general. The operative options for arthritis. I know Aaron mentioned de innervation. That would be my fifth option. But you can think about arthrodesis, excision, reconstruction, replacement, reconstruction or osteotomy. And those are really are the only four things you can do for an arthritic joint. You can fuse it, you can sometimes remove portions of it. You can do a joint replacement and you can sometimes osteotomise around a joint to offload certain parts of the joint. For example, the medial compartment of the knee, you can osteotomise the upper tibia to real the forces through the lateral compartment and offload the medial compartment to reduce pain in the wrist. The osteotomy is appropriate for ulnocarpal impaction. If the ulnar is too long and the patient's developing secondary ulnar carpal changes, shortening the ulnar through osteotomy can help. Aaron's talked about osteotomy options for Ken box but wrist replacement uh excision reconstruction, which is usually a proximal row carpectomy or arthrodesis fusion. Either the whole wrist or limited intercarpal fusion. Are your operative options. And just to remind everyone of the dorsal tendon compartments, cos again, it's quite an easy question to put through AM CT or even a a viva. The picture on the right is an MRI showing er T one. You can see the wrist compartments. The first compartment is here. Second is here there's Lister's cubicle. Then the fourth compartment is here with the third gi snuck round there. E pl the third compartment runs ulnar to Lister's UBIC and then runs a bely across the second compartment E five which is the extensor digiti minimi runs over the distal radio ulnar joint and EDC sorry EC U extensor carpi ri right round the corner in a little socket, little groove on the side of the of the ulnar. So here on the picture from ao er compartment one which is the DS compartment on the radial sty stylo compartment two housing the radial wrist extensors, E CRL and EC RB compartment three which should be ulnar to list as tubercle housing E PL tendon extensor policy, Longus compartment four EDC and extensor indicis compartment five sitting over the distal radioulnar joint, extensor, digitally mime and compartment six extensor, carpi, ulnaris, dorsal re ligaments again, revision cos we talked about this now as well. The er apex for the ligaments is the TRM bone and the ligaments are formed by condensations of capsule. The dorsal radial carpal ligament which is radius triquetrum and the dorsal intercarpal ligament which is triquetrum to trapezoid and scaphoid. If you cut along the lines of those fibers, uh raise a chevron shaped flap, reflect it gradually. You have a dorsal approach to the wrist, the berger flap, the landmarks for your dorsal approach will be just over Lister's tubercle, a longitudinal midline incision just slightly to the er ra side of midline over Lister's, you raise full fitness skin flaps and identify extensor policies, longus E PL, you reflect E PL radially from its third compartment. Here are in cross section, you can see sling around it and push it to the radial side. We then get underneath the 2nd and 4th compartments to expose the back of the wrist and distal radius. And on the right, you can see a photograph in the floor of the fourth compartment as you reflect it. You'll find the posterior interosseous nerve, which Aaron mentioned as part of your denervation tactic. We we're doing a wrist reconstruction procedure through a dorsal approach. We'll cut the post intraosseous nerve do a neurectomy uh to reduce the postoperative pain. Finally, we'll perform a berger capsulo toy. We'll be able to see the dorsal carpus er and then perform the procedure which we're planning to do so. Options for reconstruction, the proximal row, carpectomy. This is a POSTOP X ray of a patient who had APR C. And you can see that the entire proximal carpal row has been removed. And that allows the capitate to move against the lunate fossa of the distal radius. The carpus is shortened a bit and Aaron did mention that when you shorten the carpus, you reduce grip strength. However, if a patient is in significant pain due to a condition such as K box or slack scapul in advanced collapse or some other arthritic problem in the wrist, the pain will reduce their grip strength. And when you give them pain relief through APR C, their grip strength will actually improve. So P RC should not be banded as a grip strength reducing procedure. It might reduce grip strength compared with the normal opposite side, but it will improve grip strength due to improve pain. This is only possible. And Mia mentioned this too when the proximal capitate surface is completely intact and normal. In other words, if there's any sign of midcarpal arthritis, a proximal carpectomy is not appropriate under that circumstance, you'll then think about doing a limited midcarpal fusion. One of the questions that people might be asked is what are the four corners of a four corner arthrodesis? The four corners are much less important than what you're actually trying to achieve what you're trying to do because the arthritis is around the scaphoid is excise. The scaphoid P RC excites, the sc didn't it? You've lost the scape foot here, but you also had to lose the lunate and the TRM. Because if you just took the scape forward out, the capitate would slide into the gap that you've created and the capitate would then collapse, giving you further wrist pain. So the P RC removes the other proximal carpal rose to avoid the risk collapse and allow the capitate to sit directly on the, the lunate. But if you do a midcarpal fusion, fusing the four corners, that will also help that problem. So here's an example, this guy has gross dizzy. You can see he's had his scaphoid fracture fixed. Despite the fact, the scaffold was fixed, the midcarpal joint has gone into gross dizzy and this guy has a ligamentous laxity issue due to injury. His lunate is tilted very uh very dorsally and the midcarpal joint is very flexed. He really struggled to extend his wrist as we discussed earlier. So what he's had is a midcarpal arthrodesis and it can be done through a variety of ways. There is a plate with screws that can draw in the four bones together. The four corners of the four corner fusion are capitate lunate TRM and hamate. As you can see in this picture. But you can use a plate, you can use intramedullary screws, headless compression screws and you can use, dorsal staples, took the staples out and you can see now that the er capitate is moving where it ought to move in the sorry, the lunate is move where it ought to move in the lunate foer the radius. This procedure is done in non smoking. Younger patients. The main problem with trying to get an intercarpal fusion is, or arthrodesis to fuse is fusion non union. And so if you take a patient who's diabetic, old and smoking, the non union rates are unacceptably high failure rate of uh four corner arthrodesis is still probably one in six, about 15%. And so, for that reason, APR C is probably a more predictable procedure as patients get older. A proximal row, carpectomy is probably a better option unless it can't be done in this situation because we're correcting the midcarpal flexion and we're treating a younger patient. We've dealt with the mid carpal flexion by realigning the carpus and fusing the midcarpal joint which leaves the carpus as it was, the scaffold is excised. Otherwise the wrist would not move an alternative to a partial fusion. Of course, is just to do a total wrist fusion. Here's a classic AO fusion plate, third ray screws into the carpus screws into the radius allots compressed and absolute stability techniques to achieve fusion of the radiocarpal midcarpal joints. I know we talk about this next week but here's a picture of the mot. Er, the motte is a ball and socket, wrist joint replacement much simpler than the universal two, which is the one you've seen with three prongs distally. Um But er still quite a high failure rate. Wrist joint replacement has not been perfected yet. So at the moment, wrist joint replacement remains under evaluation, the main benefit of course is motion preserving. The main problem is where do you go from here when this goes wrong? But wrist joint replacement is an option to consider with your patients. So, back to the front and we're here again, asking for the treatment options for this patient. So this one does have pain and the question is the pain is coming from the wrist, not the thumb base. But what are your treatment options for this person if you're going to operate arthritis involving the proximal row? So would full cold e fusion be an option or total? Is that a question or an answer? A bit of both? I think. Um No. So, all right, Josh. So what are you looking at is um it's a slack risk, right? We're saying there was some chondrocalcinosis, there is some chondrocalcinosis. What stage of slack would you say this is, was involving uh cap skate forward? Um Stage four, isn't it? Well, stage four was never really described what I said. And stage four was pan carpal. So the only joint that's still preserved in the wrist is the radiolunate joint. So, although the mid carpal joint is completely gone, the radiolunate joint is not completely gone. So as part of your, your reconstruction, you're gonna have to remove the scale forward. But if we just do that, we're not addressing the midcarpal arthritis. And so as you say, quite rightly, you wanna fuse the midcarpal joint or fuse the whole wrist or do a wrist replacement. This case is not suitable for a proximal row carpectomy because the mid carpal joint is not suitable for that anymore. The cap joints gone. This is stage three slash. There's a good example of a case where midcarpal joint fusion would be good and that would allow some motion preservation. The lunate could still move on the radius. You'd need to remove the scap forward because that joint is completely gone and the scap forward has been eroding into the radius. The factors that might influence your decision, patient age, patient smoking, limited intercarpal fusion is poor in smokers and older people, people with diabetes. And the other thing is the chondrocalcinosis is likely to lead to ongoing chondral loss in the radiolunate joints. So your four corner fusion, which is a midcarpal fusion coupled with a scold excision might not give the patient many years of trouble free motoring. So it might well be that this er attempted reconstruction through joint preservation, er leads to secondary problems in the rad joint and a need for further intervention. So, other than doing a limited intercarpal fusion with scel excision, the other options include er, wrist, fusion and wrist joint replacement. Any other thoughts about other treatment options, you could try, if we consider an operation, non operative means, could be tried, I could risk the innervation to improve the patient's pain. Yeah. So you might, but obviously it's not operation, I mean, in terms of not fusing or yeah, just cut in some nerves though, rather than do a big wrist reconstruction. So Aaron said, yeah, what you might do is put some local anesthetic around the posterior and Antero nerves usually under ultrasound guidance. So, you know, you're in the right place, block the nerves, see how much pain relief the patient gets for an hour or two with the nerve block in place. And if they get good pain relief, you might then offer them a denervation as an alternative, doesn't clear the pitch for any uh actual joint reconstruction you could do, but it does potentially remove some of the pain they experience before you try. And even less than that, you might just try a steroid injection, although you can imagine it might not last very long or at all. So really with this one, we're left with um as you say, analgesic options, uh denervation and then operative reconstruction of the joint through either removing the sc or infusing the midcarpal joint, er fusing the entire wrist joint or potentially doing a wrist joint replacement. Any questions about slack or slack. So the summary for the talk is we've just run through some basic carpal anatomy. We've talked about the bones, the soft tissues, both extrinsic and intrinsic ligaments. The dorsal extensor tendons and the compartments in relation to the dorsal approach to the wrist. We talk about some normal biomechanics. What the scapholunate and lunar TriC ligaments do. How the lunate is the integrated segment and description of the lunate position in relation to the capitate, gives a dorsal or volar intercalated segment instability. It's more useful to think of the mid carpal joint than where the lunate is. So a dizzy with a dorsal lunate actually has midcarpal flexion and a dizzy with a var lunate, his midcarpal extension, dizzy as ball er disabling and a Visy is often well tolerated. We talk about common pathologies. We mentioned the paper by Watson and Ballet on slack wrist and a paper by Watson on snack. We've looked at some treatment options, particularly surgical treatment options including denervation and proximal carpal er row excision, excision of scaphoid and four corner fusion of the mid carpal joint, total wrist fusion and wrist replacement. In terms of reflective. That's a huge amount of information on three quite big topics in the wrist. So hopefully you can er rewatch these lectures if metal will let you do that. But most importantly is to write some reflections probably before the end of the day. So go away from the talks come back after a cup of tea in an hours time and just write some light bulb moments for each of the three talks, probably three learning points per talk things you just didn't know before, which you now know because that rere reflection and re iteration of what you've learned is the best way to reinforce those neural pathways and to reinforce the memory. So your learning point might simply be the anatomy of the wrist might simply be what a baton deformity is and some definition or classification in key box, it doesn't matter, but it would be helpful for each of you just to think about some reflection before the end of the day, before you go to sleep because once you've gone to sleep, the information will start to degrade quite quickly. Any final questions before we go on the session, Mia and I both here, Aaron's head to go. Um One question, Mister Johnson. Uh if you have a chronic um nonunion scaphoid, uh do you try to treat that or leave it for it to progress to a snack rest uh in your clinic? What it all depends on the symptoms. So, a paper by our own Laura Young and Adrian Hoyos in Norwich er was entitled Don't rush to salvage and it was talking about that. You probably should think about addressing the scaphoid nonunit itself rather than rushing to salvage of the wrist joint. But it does depend on the patient. It's quite reasonable to follow the patient up with uh annual or or twice yearly, sorry, alternate yearly review. If the patient has an established non union, if you feel that the chance of successful non union surgery is low and the patient is minimally symptomatic. So the question about fixing a non unit is, is whether it can be done. And that depends on bone vascularity. So if the scaphoid is dead, there's nothing you can do to bring it back to life. And that is my personal view about KMOX. KMOX is a very unpredictable condition. Um The li classification describes what's happening at the moment, but we're not sure absolutely whether KMOX stage three always progresses to stage four or not. Uh You can follow some patients up and see what happens and when they do progress, you can treat them and the same with the scaphoid. But if the scaphoid is dead, it's very difficult to revascularize it. And the other thing you'll know is the fewer operations, someone has the better. So it's best to give the er, the operative intervention. You're, you're going to suggest um make that be the best shot and a one off rather than chipping away at several different procedures. All of which lead to the next, the one thing none of us wants as a surgeon is to have that expression. Every operation in this patient's care was needed except for the first one. So we'll try and think about what, what, what we're doing um to minimize the interventions an unsuccessful scaphoid non in operation would lead to a second, unsuccessful scaphoid non in operation which might then lead to a wrist reconstruction, scaffold, excision, limited intercarpal fusion. That's three procedures which maybe none of them required. I don't know if that answers the question but, uh, just be cautious. Yeah, that's good. Um, thank you. Yeah.