Thank you very much. Thanks for the introduction, and I'm very happy to take part today and I'm going to talk to you about radiography of the distal limb. OK.
So, as an outline, what I would like to talk to you about is, first of all, image acquisition in general. I will then move on to the more specific anatomical regions, starting proximately with the carpus and tarsus and then go down to the fat locker and digit. We'll then talk about standard projections and also some additional views, and then I've prepared some case and image examples and at the end, I'm gonna mention some contrast radiography for the distal limb.
So first of all, with the preparation and the acquisition of distallim radiographs, restrained certainly important and always my choice for sure to do. We all probably have wasted a lot of time in X-raying unsedated horses and ending up with radiographs that are potentially not good enough. Clean the dirt and mud off, really important, especially for our foot radiographs.
It's important to try and keep the hair dry because as we all know, that wet hair can show up on radiographs and potentially stop us from seeing a lesion. Prepare the feet, so give them a good clean, clean, but also trim them and pair them out. So I think that's a really important bit.
Especially the frog regions. Make sure the hall stands square, labelling less important with our DR systems now where, that's all done for us. Make sure you're happy with your equipment settings and you set the right exposure and then coloration is important.
Two reasons, radiation safety for sure, but also for an improved image quality. Positioning aids, these are what we use here at the hospital and you can see they're really well worked in. And again, especially for the distal limb, I think they're really important, especially for foot and fetlock radiographs.
This is just an example where the frog hasn't been paired out properly and we've got something like a stone here in this case, superimposed the distal border, where we are obviously looking for around isolated opacities in cases with distal border fragmentation and that's certainly something that we can avoid by cleaning and pairing out the feet correctly. Image viewing is an important point, especially now that we've got all the portable DR systems available that allow us to instantly view the images, and this is a viewing station that we use here at the hospital and you may have similar stations back at the practise or to, to view these images in a dark room on a large screen. And I think it's sometimes really tempting and it's important to avoid making a diagnosis in the stable where you've just taken the images.
Usually, the light situation is not ideal. You may have owner pressure and the owner looking over your shoulder, and you're looking at the images on, on far too much to the screen. So make sure you take them back and have another look on a larger screen, ideally in a dark room and with suitable viewing software.
Make sure you're consistent and you have a systematic approach when looking at radiographs, and it doesn't really matter what you do, whether you start at the outside and move to the inside or the other way around. I think it's just important that you've got your own system and apply that to each radiograph that you're looking at without taking any shortcuts. And Try not to look at radiographs in a hurry.
Again, difficult for most of all of us, but try and avoid looking at at a big set of radiographs at the end of the day. And if you do, maybe have another look in the morning and you'll probably find that you may have missed a small lesion when you were tired looking at them. I'd like to do a little test here.
This is a test of selective attention. This is a video that some of you may already know, for those who don't, if you could just watch the video and follow the instructions here. This was in, so count how many times the players are wearing white past the basketball.
OK. How many puls did you count? If you counted 15 passes, you were right.
So you did that well. But did you see the gorilla? And we'll just see this here if we go back, there was actually a gorilla walking through the screen.
And when this test was first done at Harvard University, the original experiment, half of the people watching this video missed the gorilla. So what that demonstrates really is that we are missing things, unfortunately, and when we do, we don't really know that we are missing them. What's that got to do with imaging, you might think.
And unfortunately, there are also some invisible gorillas in imaging and this may be one of those examples. I have a good look at this radiograph here. This is a stifle, a lateral oblique view, and most of us would sort of along and have a look at the femoral condyles potentially looking for lesions there or the trochlear ridges of the distal femur, look at the patella, and an area where there's less frequently a pathology is potentially here, the proximal tibia, and that may be such an invisible gorilla.
You've got a very large radilucent area here in the proximal tibia, a huge cyst, in, in the bone. And despite it being a large lesion, you may miss it because you weren't looking for it. So image reading errors unfortunately occur.
There's a book, The Invisible gorilla, if you're interested, you could read, and that happens because of inattention, blindness and failure of perception. In the study from '92, that was human radiology, they found that the most common areas were that the lesion was outside of the area of interest. People stopped searching after the first lesion was found.
I think it's certainly a mistake that can be done easily. The history may not fit to the lesion, so you've already got in your mind what you think this whole should have, and you're not looking for any abnormality. Technique limitation, that's all about image quality here and of course, lack of knowledge and that includes lack of knowledge of anatomical variations.
So I think it's always important to be aware of these limitations and the, also the limitations of our mind, we are only human. So standard protocols here, I think it's important to be able to adapt the standard set of images for each individual case, and, that means, for example, in race horses or eventus horses in general that are doing fast work, you certainly have a potential different standard set of especially fetlock or carpal joint region. Radiographs and we'll go into more detail later here.
And of course, do apply lesion-orientated views if you are, if you're interested in a certain area of the joint. So starting with the anatomical regions, and I'll start with the carpus. So we've got the lateral medial view of the carpus.
The dorsal power view and the lateral and the medial oblique views. Additional projections include the flexed skyline view and the flexed lateral medial view. The skyline views, there are different ones, and again I'll go into more detail later here.
So I just wanted to go through the standard set and just to sort of define a little bit what would be a good diagnostic radiograph and in terms of positioning, I think with the carpus, that's the same with the tasks later, it's important to position the joint in the middle and to make sure you get plenty of distal radius and proximal metacarpal bone. Or metacarpal region in the picture as well. these are also areas where there's commonly, pathology, especially in the proximal canon region.
And then I always make sure I can see the joint spaces nicely, again, a good control if you've got a good or a bad latered radiograph. And another re region where you can check whether you're correct whether your position is good here is whether the cortex, the palmar cortex of the metacarpal bone and also the splint bones are superimposed so that you can look potential for potential industrial reaction here. So with the lateral medial view and also with the lateral oblique here on the right-hand side, I usually angle down the beam slightly, usually 5 degrees plenty.
And the most important part to me in the lateral mediaial radiograph is that the dorsal distal aspect of the radial carpal bone is highlighted nicely. So where you can see the cortex is highlighted here, that's an area that you really want to make sure you can see nicely and I think often this is achieved by just angling down ever so slightly distally. And this is a difference here.
So on the left we've got the angle down slightly and on the right horizontal, and on the right, you probably will struggle to correctly identify a loss of definition and between the cortex and the medulla and also the terracular pattern here and also you want to look for a really nice and neat joint space. The D D DP view, sorry, here on the left-hand side, I use the splint bones to make sure that I'm correctly positioned and have a good DP projection. And again, make sure you've got plenty of proximal cannon on to look for a change of trabecular pattern in that area as well.
Obviously, that region where the dispensary ligament attaches onto. And then on the medial oblique, what helps here I think is to shoot a little bit more from medial and to sometimes even angle up for the medial oblique that will help to get better through the Joint spaces, I think that's probably the most commonly the, the difficult projection in the knee to get right here and you want to make sure that you're nice through the joint spaces and in some cases, that's best achieved by ever so slightly angling up. Additional views, the flex lateralmedial view.
Here on the left side, you can see a nice superimposition of the proximal ro carpal bones. But really, what you probably are most interested in is again that radial carpal bone distally because that's where plenty of the pathology occurs. And what I'm looking for in a flex later medial view is that slight separation of the intermediate and the radial carpal bounds here.
And most crucial here to get this image right is usually the carpal position, so you don't want to flex the joint too much, almost trying to line up vertically do the dorsal aspect of the knee. And sometimes what happens when you pick up the leg is that the leg rotates inwards. So you, if you bring out the fatlock joint, that can help.
And then you may have to play with the angle a little bit in order to get those two bones separated nicely on your view. The skyline views of the carpus, we've got 3 different ones here. On top, we've got the skyline of the radius.
Here, what we're trying to highlight is the dorsal articular margin of the radial trochlear. So on the left-hand side, we've got our sort of CT images, and just to highlight which bones we are looking at in the middle, there is then the radiograph accordingly and on the right, then you can see which area we are actually highlighting. So the first one is the skyline of the distal radius.
Probably less frequently done. Then we've got the skyline of the proximal role, again, not, not a very common projection, but it's good if you're able to do those. And then the most common and really standard view for all racehors or horses that are doing fast work with las localised to the knee, the C3 skyline view here and this is the view you're after and you want to nicely be able to evaluate the radial facet here of the third carpal bone.
And this is how we acquire them. So starting with the distal radius, this is a video. So, first of all, for the distal radius, we don't want the leg as flexed.
A good help is here to try and have the cannon in a horizontal position. And then you're centering on the knee and your beam angle is 70 degrees, proximal to distal. Proximal role, different leg position here, you flex the knee fully, and make sure the fat lock is nicely positioned under the radius here, not stuck out medially or laterally, and the beam angle is nearest to 90 degrees as possible.
And so you have a very steep beam angle here. The leg positioning for the C3 skyline is very similar to the previous one. So again, we've got the knee fully flexed.
And the leg holder holds the limb, and the dorsal aspect to push it up and forward slightly. And again, make sure your leg is not twisted underneath and we centre on the carpus, and here the beam angle is 35 degrees. So this is a very common view that we do, as I've said, and this is now in hospital setting.
Of course, if you're out and about, that's doable too. It looks like we've got plenty of people around, but if you've got your portable DR system. And you've got a plate holder, and the person holding the horse can also hold one side of the plate.
And then you do need a third person to flex the limb and hold the other side of the plate, and then, of course, the, the person taking the radiograph. But you don't necessarily need, yeah, so 3 people plenty, you don't necessarily need 4 people. OK, moving on to an example of the carpal bound region here.
These are just really some image examples. I just wanted to show the pathology we are looking for in the C3, and we do skylines. So these are 3 different horses and the 3 different stages of pathology.
All were lame, because of carpal joint pain. And the holes on the top left here is a holes with a mild increased in density and a slightly altered terracular pattern of the radial facet of the third carpal bone, which is the most common area here. So that's the medial aspect of the third carpal bone.
Then top right, a horse with moderate sclerosis, and you can also see some enlarged vascular channels here. And then at the bottom, the most advanced stage of the stress-related pathology here of the third carpal bone, slab fracture, you can see the radiolucent line here, going through the radiocarpal bone. A third carpal bone, sorry.
Moving on to the radiocarpal bone example, I just wanted to see how subtle the changes can be. This is a horse that, initially underwent gamma centigraphy, and on the left here, we've got the bone scan images showing some increased radionuclide uptake associated with the radiocarpal bones left more than right. And these are the lateral oblique radiographs.
That would be exactly the view I would go for if I was worried about the radiocarpal bone. And and both horses, you can see a loss of definition between the cortex and the medulla of the radiocarpal bone here and some remodelling on especially the dorsal distal aspects. And here you can even see sort of radiolucent line going through that area.
Sohosis can develop small fracture lines here on the dorso distal aspects of the radiocarpal bone. OK, moving on to the Tarsus, again, we've got our four standard projections latermedial, DP lateral and medial obliques, and then we've got additional projections, the flex lateralmedial view, and the skyline calcaneus view. See you again, important, make sure the cannon bone is visible in the radiograph and you've positioned it nicely so that you can also see the approximal aspect of the calcaneus.
Another good sign that you have got a nice large media radiograph is that the trochlear ridges are superimposed here. And only if you've got a true lateral picture, you'll be able to assess the talocalcaneal joint. And this is a joint where horses obviously can also develop osteoarthritis, and I think it's important, that's the only view where we can see this, this joint really nicely out in the park.
I think it's important to make sure that our lateraled view is through that joint. And then of course, we've got the distal tarsal joints here and again, you want to make sure that you're through the joints correctly. And here I think it's important to not overinterpret possible apparent joint narrowing because sometimes if we are not 100% lateral medial to those joints, the space can appear narrowed.
Make sure you look for other signs. Make sure to remember that joint narrowing is really a sign of very advanced osteoarthritis. So if you feel you've got joint narrowing without any other signs of osteoarthritis, like, for example, osteop formation or subchondral bone changes, then maybe just check that you are definitely have a have a correct projection and looking through the joints correctly.
And the lateral medial view, same, same rules apply. Both views are best achieved through the joints, especially in the distal tarsal joint region, if we angle down the beam 5 to 8 degrees, proximal to distal. Then we've got the DP view here on the left again, making sure you're nice and centred and straight.
If you are slightly oblique, the proximal canon region can appear more dense, which may lead you to false conclusions. So you can only assess the density here if you are truly DP and not too bleak. And then the medial oblique view, make sure you're bleak enough to show the intermediate rich here of the distal tibia, common side of osteochondrial disease.
And again, you want to make sure that the trochlear ridges are separated enough, and again, I always find that the system taculum tala and the separation front gives me an idea how oblique I am, and you want to say equal parts on, on either side of the radiograph. The flex later media view is a radiograph that's less commonly done, probably the most indications we get here in horses that had a trauma or kick injury in the region, it's particularly useful to highlight the back of the tibia here and . And sometimes it is also really useful to look at the proximal canon again.
So if you make sure that these areas assessed properly for any possible increase of density, that can be useful, and that's maybe a reason why we might take a Flex view as well. The skyline calan is more common if you've got horses with swelling or trauma in the region of the point of the hock. Here, you want to flex the hind limb as much as possible.
The beam angle is as vertical as possible, and the plate is positioned under the point of the hock. This is certainly a view where you have to make sure it's safe for you to do. And this is a view of acquiring the skyline.
So again, you want to flex the hook as much as possible, and what can help if the horse is safe enough to do that, if you push with the shoulder, if the person holding the leg pushes with the shoulder, the leg out, you will be able to have a steeper angle. So you want to try and be as steep as possible with your beam here and that's, that's easier if the leg can be pushed out backwards. OK.
Let's have a look at some examples in the tarsus. So, this is a horse here, that has an avulsion fracture of the right hand proximal the metatarsal bone, an endurance horse, and, here you can see really quite nice. That a marked increase of density in the right compared to the left and that really abnormal tubecular pattern again compared to the left.
So this is why it's important in your hoc views that you always include the proximal canon. These are the other imaging modalities. This is a bone scan view here showing.
An increased, radionuclide uptake associated with exactly that area. And this is the ultrasound scan showing the proximal suspensory ligament from here to here. And you can see that marked loss of fibre pattern.
This is the third metatarsal bone, and you can see that avulsion fracture here with the hypeecagenic region right within the proximal suspensory ligaments, and that's all the same holes. And this is just to highlight the Tylocalcaneal joint that I mentioned earlier. This is a horse that had osteoarthritis in exactly that joint.
This also has osteoarthritis in the proximal intertasal joints, 14 year old Australian dressage halls, with very obvious left hind limb lameness. And what you can see here is true joint narrowing, and you can see significant subchondral remodelling here in the talocalcaneal joint as well as the proximal intertasal joint and marked remodelling here. OK, moving on to the FETlock joint, again, we've got our 4 standard projections.
Additional projections include the flex lamed view. The proximal distal oblique views. And the flexed dorsal palma or planter or dorsal views.
So again, here, really important to have a true lateral radiograph, otherwise you will miss things and make sure you can see nicely your sagittal ridge and the sesamoid bones are nicely superimposed. You've got here a horizontal beam. Centering on the fetlock joint.
On the lateral standard lateral oblique view, we do, we always angle down from proximal to distal 20 degrees. That allows us to assess the space between the proximal P1 and the proximal sesamoid bone, where you may frequently find a fragments in that area. Then I personally like to do a medial oblique and so we'll spin the holes around and acquire the other oblique from dulsaled.
And of course, that's, you don't have to do that. You could do a PLDMO. The reason I prefer the medial oblique to that is that in the PLDMO the object film distance is increased, and your plate can obviously only position, be positioned in front of the foot, whereas on the other view, you've got it right at the back of the fetlock joint.
And an increased object film distance can then lead to magnification, distortion, and blurring of the images, which results in reduced image quality. Again, on the standards, Dulsal Palmer view, ideally, we want to again angle down about 20 degrees. Again, that frees us up the space and allows us to actually look at the FEL joint space.
If we did a horizontal view, the distal aspect of our sesamoid bones would be superimposed. And this was this view shows quite nicely here, and this is where we try and do some sometimes tangential views of the distal metatarsal or the metacarpalbo the distal cannon. And that's because our articulate surface of the distal cannon curves 180 degrees.
And on the DP views, we only have limited part of bone and joint, that's visualised. And if we're looking for pathology, frequently we look at pathology at the back of the joint. Again, resources, particularly, frequently have the so-called pod lesions.
So, Palma planar osteochondral disease, and that's the back of the condyles. And if we suspect pathology in that region, it's important to do several views. And here we need to get the sesamoid bones out of the way, in order to visualise the palma or planar condyle.
OK, so this is how, in the forelimb, the flexed DP view looked like and in some cases we do several different views here and so it's worth doing 12 or even 3 different views to really try and assess as good as possible those condyles and in the forumb we'll angle up at 10 degrees. And here the toe of the foot is then placed in the standard navicular block, and then we lift the limb under the carpet just before the acquisition. Again, the beam is angled up approximately, and here it's really important to be aware that artefacts are very common, especially if our projection is not 100%.
Another thing to point out in the forelimb, the shape of the proximal sesamal bone is different. The hind limb and hind limb, the sesame bones are shorter. This is how we would take a flex DP view, so position foot here in the block.
And make sure here that the cannon bone is horizontal. That's the trick in this view. The more horizontal, the better you will achieve the lift here.
You're centering on the fat lock joint, lift the leg up and your beam is angled about 10 degrees approximately. In the hind limb, we've also got a flex view to achieve the same thing, the flex plant or dorsal view. And here the hind limb is lifted up by the plate holder holding the tibia.
It's important to lift the leg high enough to achieve a right angle in the tarsus. And then we shoot with a horizontal beam orientation. Again, here you can see the shorter shape of the proximal sesamoid bone and this is how we would acquire.
This photograph here, just see the right angle of the task here. Plate holders making sure line up nicely and again I've got a horizontal beam. Here, the most common mistake really is that the leg is then held out to the side, too far lateral or to the inside too far medial, and that will then result in an oblique view.
So that would always be the first thing that I would check if I wouldn't be happy with my radiograph and would have to do a repeat, make sure the leg is nice straight up and down and not twisted to the inside or to the outside. Then we've got proximal distal oblique views, and we've got two different ones. First of all, here, the lateral medial view basically angled 45 degrees from proximal to distal.
This is probably the yeah, maybe a more common view we do and that's particularly useful to highlight the axial surface of the medial proximal sesamoid bone here. So, A is the medial. Sesamoid bone, if we are shooting a lateral medial view and B is the lateral and what we can highlight really nicely is the axial surface of the sesamoid bone, so the area of the insertion of the suspensory ligament branch.
The other oblique view is basically a lateral oblique, but also angled down 45 degrees, very steeply and what we can highlight here is the lateral condyle on that view. And again that may be useful if you are unsure on your flexed DP views or you just want a little bit of extra information. And it really moves nicely, the proximal sesamoid bone out of the way.
And if you compare medial to lateral. You will be able to assess the degree of density compared, comparing both condyles. OK, a couple of examples of fetlock joints here.
So this is a case that had moderate to marked ladenner localised the fetlock joint. We've taken a full set of radiographs, but I'm just giving you, these two views here because they are the ones that showed the most. And really, that's probably not much.
And I think sometimes radiography of the fatlock joint can be a little bit. Disappointing, you've got a a fairly lame horse and lane is localised to the joint, and your radiographs may only show very, very subtle changes that I guess we also see in sound horses sometimes. So I've put the arrows on here on mild pericular changes here.
Don't forget to assess the articular margins of the sesamoid bones as well. And this horse had repeated lanes localised to the fetlock joint and it was quite lame, so people connections didn't want to go on with it, so we got to do a postmortem and I just wanted to show you how the cartilage looked in this horse. You've really got severe full thickness cartilage loss in the fat lock joint here causing the holes, the.
And this was a 6 year old point to point racehorse and that's severe pathology in the joint with only some mild radiological changes. So, just bear that in mind, when you do have these fatlock cases and the don't quite make sense, is then worth considering other imaging modalities, whether that's an easy ultrasound scan or whether you're considering an MRI scan or in these cases where it's about the articular cartilage, maybe in diagnostic arthroscopy may be the way forward to actually visualise the, the, the joint surface. And this is another case here and this is actually just looking at the source trotting up.
this was a very interesting case, so I'll just let you have a look what you think layers wise. So who's coming back? I probably wouldn't comment too much on here, nothing, nothing consistent, nothing too obvious.
So I always lunge horses on different surfaces as well. This horse was then lunged on the heart surface on the left rein. And again, nothing too much, sort of occasional night for maybe.
And then we put the horse on the right rein. And the horse is obviously lame. So this first of all, illustrates how important it is to lunch the horse.
So, you would have missed this really quite significant lameness if you wouldn't have seen this horse on the lunch. This horse went on to be blocked, and it was partially positive to the fatlock joint intraarticular, diagnostic local anaesthesia here, and negative to an abaxial sesamoid nerve block. And then the whole thing sound, the 4 point nerve block, but did not switch.
And these are the radiographs, let you have a look. Again, we've done a full set, so I'm just giving you a selection of images here to look at the natural medial view, potentially, not too much to see. Then we've got the standing DP view.
And here you can see how important it is to have the right exposure and good image quality, because in the right front, we can see in the proximal P1, you can see a thickening of the subchondral bone plate, and within that thickening and that increased density, you can see a radiolucent area. So, this was also had flex views and in this case, it just highlighted again, this radiolucent area here in the medial proximal P1 surrounded by sclerosis. So this was a horse that had a subchondral cyst-like lesion in proximal P1 and again, without good image quality, you would have been very likely to miss this.
And this is also a good case to illustrate how important it is to launch these horses on, on different surfaces if safe, if, if, if, if you consider that safe enough. OK, moving on further distal now to the digits, and here I would routinely do 5 different views. I'd do a lateral medial view.
I'd do 2 flexed DP views, one focusing on the P3 on the pedal bone, and one to focus on the navicular bone. Then I'd do weight-bearing DP, especially if I'm interested in lateralmedial foot balance, and then I would always do a skyline of the navicular bone. Additional views would then include flexed or standing oblique projections, and that's both of the pasta or of the of the pedal bone.
Just again, important, make sure you clean the feet if you've got dirt, and that can be particularly tricky sometimes with horses that have plenty of hair at the coronary band, a lot of dirt can be really difficult to remove. So these wire brushes can be really useful. And remember that the reason For artefacts on your navicular views usually is the back here, off the heel because that's where you get the superimposition from the frog.
So that's the area once you want to clean and ideally also pair out. So foot preparation would include ideally to remove the shoes. And then clean and trim the foot thoroughly and then pack the feet.
Again, that's particularly important for our navicular views, and that's the frog sulcus and the groove and consider your foot confirmation and here you may adapt certain views or certain positioning and just be aware that artefacts are really, really common. So if you've got a finding. Always make sure you haven't got an artefact and it is a real finding.
And the lateral medial view of the foot can be really, really useful, and you get a lot of information off it if your projection is good. And this is probably one of those views where it's the most crucial to have a good true lateral view, and to make sure you've got that, you want to make sure you can assess and see, both the proximal and the distal interphalangeal joints nicely. And another thing I look for in a nice radiograph, a good sign for a good radiograph is that your palmma processes, your wings of the bone are nicely superimposed here.
That tells you you are right in the sort of proximal to distal orientation with your beam. And you've obviously got a horizontal beam, and then you want to make sure that the cortex of your navicular bone is superimposed as well. And then you can assess these areas nicely.
And you can just see if you're slightly off la medial and that's not far, you really struggle to see these things, nicely. And I think the biggest struggle is then the navicular bone, and this view, I would consider non-diagnostic. You've got two cortices, so you don't really know what you're looking at there and you won't be able to, to, to.
Describe the definition of the cortex, you may be missing a fragmentation or spur in the coffin joint. And here, if you can see that the alma processes are not superimposed, that's always a sign that you're not truly lateral. So what to do if we get a radiograph like that?
Well, first of all, the radiograph radiographer needs to make sure that the projection is right. So you're centering on the navicular bone, and the navicular bone is just below the coronary band and in the middle, between dorsal and palm palma, if you think of it as a line there, and you can use the heel valves to line up. And you want to have a horizontal beam.
So that's as a radiographer to make sure that that's those boxes are all ticked. But then also, whoever is positioning the leg needs to be careful. And here you can see if you have the leg stuck out to the side, you've got a twisted foot and you won't be able to get the radiograph lateral with the horizontal beam.
So best to make sure to bring the whole leg medially right in front of the horses, not stucking out the, sticking out to the side and to line it up nicely. And then it could be the horse's fault, and some horses have such a significant imbalance that despite you lining up and positioning nicely, you still can't, can't get the radiograph right. And these cases, you can want to consider adjusting your beam or for the ferrier to level these horses up first.
So they seem straight, but the position of the pedal bone isn't. So I personally like to do two views, to flexDP views, and here on the left, that's the P3, and then on the right, you've got the navicular bone. And for both the beam is horizontal.
Some people like to do the two in one view, and I don't think there's any right or wrong. I think there are very practical views that can be done as well, and that's shown here right at the top. That's the view where we use the tunnel and angle down 60 degrees and the slight downside is that you get a little bit of image distortion here due to the angle.
The beam is oblique to the cassette, and that's where that distortion comes from. I, I prefer doing, doing a separate view here. And, the important part is to get the navicular bone in the right position on your radiograph.
So you basically, want to between the coffin joint and P1 superimposed onto P2. So that's a navicular bone obviously here. And you want to have it nice in the middle of the tune, so you can assess both the proximal and the distal border on this view nicely.
And this is how we would position for a view. So, put the foot in the block here, and the cassette goes behind and then you've got a horizontal beam centering on the coronary band. Now what happens if you don't get that nice superposition on P2, what you want to do is you want to adjust the position.
So ideally your pastton is here nicely vertical and if you're too straight, the navicular bone distal border will be super impulsed with P3 or the coffin joint. Or like on the left, or you're like a sort of knuckled over over flexed, too flexed for this view. And your navicular bone, proximal border will be superimposed with the proximal interphalangeal joint.
And so this is, this is sort of where you then have to correct your positioning and keeping, keeping a horizontal beam. And again, making sure that you don't get any, any artefacts, and this is a horse here that had a just water fragment embedded in the distal doesn't read in para ligament and you can see the fragment right here. You can imagine if there was only a little bit of superimposition.
Like full like positioning or artefacts due to, insufficient trimming or preparation, you would potentially miss, miss such a big lesion. Skyline navicular bone, again for me a routine view. A little bit difficult sometimes to take depending on the horse, position of the limb should be as far back as possible.
The beam is then angled proximal to distal 50 degrees. You're centering between the heel bulbs, and then flat-footed horses, you may want to use a wedge, a wedge block to lift the heels up. And so here again have you to make sure it's safe to do.
So I've got here a couple of videos. Number one, first video here is leg positioning. So you really want to try and bring this leg backwards as far as you can.
This is the tunnel we are using, so the cassette is placed in the tunnel. And then the leg is positioned nicely, a lot easier than a sedated horse. You want to make sure that the horse then puts the weight back and puts the heels down, OK.
And then the X-ray machine goes in. And this is the part of to make sure your horse is safe and nicely sedated. Going right close to the heel here, centering the centre of the heel bulb and angling 50 degrees distally.
Weight-bearing DP really nice view also for the farrier, to have a look at, especially if you're interested in assessing lateralmedial imbalance. It's good to use a block to position the limb because then you can centre the level of the soul. If you centre higher up, you don't get a true idea of soul depth and you want to.
You want to centre as distal as possible. Obliques, bleak views here, particularly nice for the past and joint, but you can also oblique the coffin joint nicely. This is the wall where we left the shoe on, so we were interested in the past and joint region.
So you've got a 60 degree oblique view here with the horizontal beam and the limb in a flex position. And then this is a flat angle for the Palmer processes of the pedal bone. So here you want to think DP and go slightly oblique, a lot less oblique, and to highlight your Palmer process, especially important for horses with potential pedal wing fractures.
OK, last one, I just want to go a little bit into contrast radiography of the distal limb, just sort of in terms of getting the most of our distal limb radiography, certainly something to consider. And what I want to talk about in, in particular is contrast radiography of the digital flex attendant sheath and especially to evaluate the manica flexoria. This is something I routinely do for horses that are presented with a digital sheath, effusion, and here, this is what we're looking at.
This is the, paper from EBJ in 2013 describing really nicely in the methods how to do it. So if you are interested, this is the paper to, to look at and . Basically, what happens is here that the radioaque contrast layers itself around the structures within the tendon sheath, and we are getting to see two things here.
One is the deep dish of flexor tendon highlighted in blue, and also the manica flexoria we see. The outlines and I just like to draw your attention to the line, dorsal here to the deep dal flexor tendon. So this line here, what we are looking for is that the dorsal outline of the manica flexoria and the one between the two structures is nice and parallel.
And this is an example here of a normal horse again on the left, so you see the nice parallel lines here, and then of an abnormal horse here where you basically have a, you can't see the manicalexoria and it's approximately displaced here. This was a horse that had torn the medial aspect of the manicalexoria completely. That was confirmed in surgery.
Now, why is this so important? And that's what these papers highlight. I'm gonna show you now.
So this publication here looking at 76 cases from 2006, they found that the two most common diagnoses were digital flexor tendon tears and manica flexora tears. Slightly disappointingly though, that was that the, these lesions were only accurately predicted with ultrasound in 50% of the horses. And as much as we're probably getting better at ultrasounding these areas, I still think there's a certain population of horses and that may be due to certain breeds, but also to how experienced you are and how frequently you scan this area, there's a certain number of horses where we miss these lesions and don't predict them correctly.
So what can we do about this? Well, that's where the contrast radiography comes in and just quickly, the reason why it's so important to distinguish these two, and that might be how you advise your clients, this was here looking at Chairs of the manica flexoria in 53 horses. The horses that underwent surgery, nearly 80% of those returned to full athletic functions, so really quite a good prognosis.
That's very different with the deep digital flexor tendon tears. Interesting as well was that particularly cops and these heavy horses were affected cops and ponies, 83% of the cases, hind limbs more common than forelimbs. And again here we found that, or they found that there was a reduced sensitivity.
In, in the ultrasonographic detection of the mandiphalexoria injuries, and that's commonly because of the very typical skin thickness. And this is a bit of an extreme case I've had, but there's really clinical examination and auto sonography, no hope, and that it's good if you have another imaging modality and another test up your sleeve to look at these horses' tendencies. And this is just a paper sort of looking at the outcome here of the teachers reflex attendance.
So your other most common cause of pain localised in the tenancies, only 38% of these horses returned to previous level of function. So the contrast radiography and the evaluation of the manica flexoria will really help you to discuss the plan with your client if you've got a horse where you can see a pathology in the or suspect pathology in the manica flexoria, it's really worth going down the surgical route because if they have that tall manica removed, nearly 80% of those horses return to previous athletic function. And I personally incorporate this test, in a routine workup, and you can do it together with the block.
So together with the local anaesthetic, you can mix it in some contrast and, yeah, and, and take, take the radiograph while you're waiting for the local anaesthetic to take the effect. So you're really not using, losing much time. OK, so, that brings me to the end of the talk.
Just to summarise, make the most of the distalline radiography and consider things like, contrast radiography, patient preparation, always very important, and be happy to adjust your standard protocols to lesion-oriented views, and make sure you have different protocols for horses of different disciplines. And to make sure you follow a systematic approach of image viewing and interpretation and be aware of your limits and so good quality radiographs for sure increase our chances of reaching a correct diagnosis significantly. Thank you very much and I'm, I'll be glad to take any questions.
Thank you very much, Caroline. Great, great talk. Will admit I did miss the gorilla, even though I've seen that, which is even worse.
Great. So just before we, go to questions, I was just wondering if people could, just put in the chat box, where they're listening from, and we're just interested here at the webinar it, just, how far reaching the, the congress has been. So just interesting to where in the world, people are listening from.
So I think a crucial part of the talk actually, the, or quite take home message was, attention to detail, in actually taking the X-rays is probably pretty important. What, what do you think are the common mistakes that you see when it comes to imaging, you know, regarding taking imaging and also potentially, interpreting images? What are the most, sorry, what are the most frequent mistakes, the frequent mistakes.
Yeah, I think, you know, I think that often we are missing the obvious, and I think we're doing, we are, we are being rushed and I think we're all busy. And there's always a lot of client pressure. We always put the extra two cases in and if you write your report at the end of the day, and it's just you looked at the radiographs, I think it's easy sometimes to miss obvious things and it's happened to me and it will happen again, I'm sure.
But I think being aware of of these limitations sometimes and sit down, ask a colleague, make sure someone else reads the images as well, . And, and really take your time or by all means, write a report in the evening, but then go through the images one more time in the morning. I know it takes extra time, but really, it's worth it in the end, and it, it happens to me.
I, I often read my sets of images of my cases 2 or even 3 times, and I will, I will then the second time I read them pick up things that I didn't see the first time. So you increase your chances of picking, seeing the lesion if you read them more than once. And the team is certainly helpful as well.
And I think the other another really common error is that the image quality is just not good enough. So people are really, really good and doing exactly these things and reading the images, but then they, they are reading images that are not perfect. And if you then go in and change the angle ever so slightly, you suddenly see that bloody fragment or you see the radiolucent area.
And that's that's I think where it's really important to make sure that you are spot on with your radiograph. And, and first of all, it's, it's recognising what is a good. Graph, and what is a good projection, and then not giving up if you don't get it and go there and, and, and unfortunately repeat the view.
Yeah. Yeah. And I, and I guess if you aren't taking the correct X-rays or you miss like a fragment, then you can go ahead and do expensive MRI only to turn out that you probably could have seen it if you did a decent.
Yeah. Exactly that. Exactly that.
A lot of time and hassle for the owner of the horse, possibly. Yeah. OK.
that's it, for all the questions, it was, yeah, a really, really thorough talk, really, really interesting and really good images and really clear how, how to show how well, how to take all the views, and we have people listening as far away as the east coast of the USA. So well, national audience. Great, yeah.
So, well, I'd like to thank all our speakers, for this afternoon, so Tim Barnett, Kevin Cawley, and Caroline Gertes.