Good evening everybody and welcome to another equine webinar tonight. We are looking at ultrasonography of the Stifle joint. My name is Bruce Stevenson and I have the honour and pleasure of chairing tonight's session.

I think we have a few new people on tonight, so just a little bit of housekeeping for you. For those of you who want to pose a question through to our presenter, Caroline tonight, if you hover your mouse over the screen. You will see a little control bar that comes up.

You simply click on the Q&A box, type in your question there. It'll come through to me and then we'll hold those over to the end, and then we can pose those questions to Carolyn. So if you've got questions for her, please don't hesitate to pop those through.

It is my pleasure tonight to welcome Carolyn, to the webinar. Carolyn qualified as a veterinary surgeon in 2007 in Hanover in Germany. Before moving to the UK she worked in a busy sports horse practise in Bremen in Germany.

Then in 2008, Carolyn joined the team at Rossdale's equine Hospital in Newmarket. After completing the diagnostic imaging internship in 2009, she stayed on as an orthopaedic assistant. She's then working as a senior clinician at Rosdale Diagnostic centre, seeing referral cases for a wide variety of disciplines.

And just recently in the last month, she's moved back to Germany and she's now working in a big equine hospital there. Her special interest is orthopaedics, diagnostic imaging and poor performance investigation. Who better to present ultrasonography of a stifle?

Carolyn, welcome to the webinar, vet. It's over to you. Good evening, everyone.

Thank you very much for the kind introduction and welcome everyone to the webinar on ultrasonography of the Stifle joint. OK, and first of all, I would like to say that all sonography of the stifle, I think is a modality that should be used a lot more. It really helps us visualising the soft tissue components and also the bony contours a lot better.

And then the only radiography does. It is also something that's very useful for the practitioner as things like MRI or CT and contrast CT are not readily available. MRI is not practical, only a few.

areas or few places where that is available and really ultrasound is then our only modality to widen that diagnostic window further to give us some additional information, or additional information to the X-rays. It's really important to use a systematic approach in the stifle joint. It's a really complicated anatomy and it is also a large joint.

And it always helps me to divide the joint into four main areas, the medial aspect, the cranial aspect, the lateral aspect, and the cool aspect. I would like to show the normal ultrasonographic appearance of the most important structures tonight of the cipher joint, and then I've also got some examples of abnormal findings. First of all, looking at the technique, what do we need to scan a stifle joint?

Well, we don't need all of those probes shown here. I think if we've got a, a linear probe, you can visualise the most important structures of the stifle joint. But if you then want to go a little bit further and scan that a little bit more, the microconvex probe can be really helpful in the flex stifle joint, and we'll talk about that a little bit more later.

And the low frequency sector probe can be really helpful and the the convex probe here can be really helpful to scan from, from the caudal aspect, maybe the least common approach used to scan the stifle, at least for me, but certainly for that, for the caudal aspect because there is so much soft tissue between the joint and the probe, we need a different, different approach there. But you could also use a rectal probe to, to as the linear probe to, to ultrasound scan the most important parts like the medial aspect. So the four approaches here, this is a horse basically facing us, the stifle joint, and this is one that's what's quite rare, a horse with a visually distended medial femo tibial joint where that probe is held onto.

And this is how I approached the standing horse. I always start on the medial aspect and then scan, ideally longitudinal first and then transverse planes. And then move over to the cranial aspects, stick to the weight-bearing limb in the first instance and assess the femoral patellar joint.

And then move on to the lateral aspect and assess the lateral femitibial joint and closely associated structures. You can then, if you want to visualise the joint from the caudal aspect, move to, to that area and visualise the caudal parts of the medial and lateral permitibial joints. And once I've scanned the leg in a weight-bearing position, I then go on and scan it in the cranial, in the flex position.

And this is always what I do, standing, medial, cranial, lateral, then flex the limb and scan cranial, and that's what I routinely do for all cases. And then there is the possibility to scan the stifle from coal, which is something that I don't do routinely in, in, in, in all cases. So let's start with the medial approach.

These are the areas, these are the structures that we want to try and visualise here. So most importantly, the medial meniscus, and we can assess the structure really nicely with auto sonography here. Then we've got the proximal pouch of the medial febtibial joint.

Again, the structure that's really nicely visible ultrasonographically, the medial collateral ligament, then we've got the medialfemoondy, the distal femur, and also the tibial plateau, the proximal tibia. And this is a specimen here prepared, so we have cranial, to the left portal to the right, and to get the ultrasound image here on the top left, the probe is positioned in the longitudinal orientation or frontal plane. And in all ultrasound images in this talk, the proximal aspect and the need aspect are to the left.

So on the left-hand side, we've got proximal, the right side, we've got distal. And the bright blue box here, the specimen shows the position of the probe. So first area that we can look at here are the bone surfaces, the femur and the tibia.

And here we are looking for smooth and evenly curved bone surface, and this is really the area where we are looking for possible osteophyte formation, and we want it to be, as I say, smooth and without any, any spur formation. Then the meniscus is here the homogeneous structure, triangular structure, and it's got a, an ecogenicity very similar to the cross-sectional area of tendons and ligaments, and it's obviously wet-shaped here. You can see it quite nicely.

And then these errors are now pointing on to very commonly seen artefacts. There are these vertical hypoecogenic lines that run perpendicular to the probe, and they are just caused by the, possibly by the joint. Capsule attachment and possibly also vessels in that in these areas.

And what the trouble is here, it is just a dropout artefact and sometimes the tears can run in a very similar orientation. The best way to figure out whether this is an artefact or not is to move the probe slightly. And you will then see that these hypoecogenic lines will move with your probe, and then you know for sure, this is just the artefact that's very commonly seen in this area.

And then we've got the medial collateral ligament here in purple, and then we've got superficial and deep parts that run slightly obliquely to each other, which means that to really show it nicely, you have to sort of slightly rotate your probe in order to assess all parts and get it nice, nice and, and perpendicular to, to your probe and assess the fibre pattern. And this is just the same in the video, and here you can see, I'm tilting the probe slightly back and forth, play a little bit with the off incidence ar artefact, and just really have a good look at that area and move backwards and forwards. Ideally, then you want to move also proximal and to the proximal attachment of the collateral ligament and also distal to the distal aspect.

And assess that area nicely. So the medial collateral ligament runs slightly caudal to the to the proximal pouch of the medial femotibial joint, and that's when we then look into possible pathologies. That's something that's we find very commonly.

So no a thickening and effusion of the medial femotibial joint. I've got some examples for you in a moment. And then, of course, the median meniscus, we might find signs of degeneration and possible tears.

And in the collateral ligament, we might find signs of desmitis again, enlargement, loss of longitudinal fibre pattern. Medial meniscus pathology is very common and so is the synovitis in the medialfematibial joint. Pathology in the medial collateral ligament, is, is rare or rarer.

OK, so if we then move the probe from the collateral ligament, which is slightly further caudal, further cranial, we'll end up on this pouch. And in a very normal ho, it should be a small joint pouch and the fluid should be anechoic. And there should be no signs of synovi proliferative tissue.

The joint membrane should be very thin and even, and certainly, there should be no fluid on the axial or distal parts of the meniscus. And I'm just gonna try and point that out to you. So this here, where the joint capsule attaches, there shouldn't be any fluid on this side of the meniscus or on the distal side.

Then we can get horses that have a mediairmatial joint distension, and that's then also visible ultrasonographically. And this is really, really common also in horses that are clinically normal and sound. Interesting to see in this case here that yes, we've got synovial distention, we've got an enlarged joint compared to the previous example, but you can still see that the synovial lining is very neat and the synovial membrane is very thin.

And there's no fluid on the other side of the meniscus, and there's no signs of obvious synovial proliferation. So no signs of inflammation in this distended joint. That's very different to this joint.

This is also distended, probably even larger, but you've got the marked distension with synovi proliferative tissue and hypertrophy of the synovial lining here and the synovial tissue. Also, the joint capsule is very thickened here between the red arrows, and you get these hyper-ecogenic areas within the otherwise unnechoic synovial fluid. This is a joint that's very distended and very inflamed looking.

And I, I think this would be a much more likely a horse that's lame because, because of this. Of course, it's always important to combine our ultrasonographic findings with diagnostic local anaesthesia and the clinical findings, especially in the stival joint, but this is a very, very distended joint. The other interesting area I'd like to point your attention to here is the distal femur here, and this is here in osteophyte formation.

Remember on the normal example from earlier, we've had a smooth, nicely curved, joint, sorry, bone surface, and here we can see the new bone formation and the osteophyte formation. So this is an osteophyte. And the distal femur.

And this is a stifle joint, again, that's maybe not as big as the example from just before, but again, you've got marked thickening of the synovial lining and also some hypertrophy and synovial proliferative tissue. But also, if you can see between the light blue arrows here, you can see all that hypertrophy abaxia to the meniscus and also on the distal aspect of the meniscus between the red arrows, we can see some synovial fluid. Again, this, these are all signs of a very inflamed stifle joint, and this is always something that's abnormal.

We then concentrate on the meniscus a little bit more, here on the top left corner, that's the example of normal and something that tells you that there's something wrong with the meniscus is also the position of the meniscus between the femur and the tibia. I always try and draw a dotted line between the bony surfaces, and then I don't want that the meniscus protrudes significantly above that line. And so you can see this example here where there's a horse with a very severe joint pathology, that the meniscus is significantly protruding across that, that imaginary line between the bony protuberances.

And this is always a sign of, of severe stifled joint pathology and a possible you would what you would see potentially on a, on a radiograph here is narrowing of the joint space as well. OK, then on the right side, there is a horse that has a an osteophyte here and I have to say these osteophytes are more obvious and easier to identify ultrasonographically than they are radiographically, but they are not always clinically significant. So that would be a common finding also in the sound halls.

And then here on the bottom left, we've got a meniscal tear here in that light blue circle. You can see that heterogeneous appearance and that hypoecogenic area there. This is a clear torn meniscus, and again, also, in that same picture, the arrow is pointing.

Out a very marked osteophyte formation, again, as a result of of of severe joint damage. And also here on the bottom right, we've got another meniscule tear, and again, you can see how heterogeneous the meniscus now appears in this image with that degree of pathology and also here, the meniscus is actually protruding outwards. Now, when we think about auto sonography to assess the meniscus, it's also good to be aware of the limitations and we can basically assess really nicely the middle part of the meniscus, and I think the ultrasound is really, really strong.

The other parts we can't assess, that's them where arthroscopy comes in, and these are the areas where arthroscopy has, has the strength, where we can assess these parts. So this is also sonography again, as a part to sort of as a to to complement the assessment of the tier joint using also other modalities like for example, arthroscopy. OK, so when we've, once we've assessed the medial aspect, we move over to the cranial aspect, and here I'm particularly interested in the femoral patella joint.

So we can visualise the patella, we can look at the patellar ligaments, the three patellar ligaments, the medial, middle, and the lateral patellar ligament. Then we can visualise the distal femur and the lateral and medial trochlear ridges, the trochlear groove, and also the tibial crest. Again, for this approach, best use a linear probe and it's, it's, it's a very accessible part of the joint.

OK, so starting with the patellar ligaments, so we've got a, again, I started doing preparation here where I've left on all the three patellar ligaments, and the middle patellar ligament is certainly the most interesting one, in terms of demitis, that's the one that's most commonly affected. And, we want to assess the whole ligament in longitudinal and transverse plane, so all the way from the distal patella to its insertion onto the proximal tibia. Autographically, we get a really nice sort of round shape a structure here.

It should appear homogeneous and as we then follow a little bit further down, just so, and you can then also turn your probe and obviously assess the ligament and its insertion onto the onto the tibia here. If you turn your probe around right above at the point of insertion, so in this picture here. You've got the patellar ligaments and insertion onto the tibia, you get that very typical reticulated pattern, which is absolutely normal.

And sometimes you get this pattern a little bit also further proximal. So if you aren't sure about whether this is normal or abnormal, make sure you compare both sides and also look for other signs of desmittis, such as an increase of the cross-sectional area and maybe also some perilligamentous changes. Then we've got the media patellar ligament, which is rarely affected by demitis, but maybe more interesting to, to check out and see whether there's been any surgical procedure done.

It's a very easy to assess. It's, it's this triangular shaped. A ligament here on the medial aspect.

You can see the medial trochlear ridge in this picture as well, and the arrow is pointing to the cartilage, which is unechoic here, and it's a lot thicker on the axial aspects to allow the patella to glide in that area. And when I go a little bit further down, it's always nice to get this image here and we can visualise both the middle patellar ligament on the right, which is a lot larger and rounder, and the medial patellar ligament here on the left. The lateral patellar ligament is the largest out of the three, and again, pathology is rare compared to the middle patellar ligament.

And the most commonly we'll see here, pathology as a result of trauma, whereas in the middle patellar ligament, you will commonly see, more commonly see degenerative changes. And in this image here, we've got the lateral trochlear ridge again here actually a thicker cartilage for the patella, and the ligament is here this entire part, and it's basically positioned directly over the lateral trochlear ridge, easy to find. And in this picture here on the bottom, we've got an abnormal ligament.

This is a holes that's had a trauma to this area here, and you can see the irregular appearance and the hypoecogenic areas and also the enlargement of the overall enlargement of the cross-sectional area of the lateral patellar ligament. The trochlear ridges and also the trochlear groove are easy to assess on the cranial aspect of the stifle joint. And here again, it's nice to start with the transverse plane.

I always like to assess the trochlear ridges separately to start with, start with the medial, then move on to the lateral, and then I also make sure I assess the trochlear groove in the middle. And here what you want to see is a very nice and smooth subchondral bone line here highlighted in blue. And then on top of that, you want to see a nice and even.

Area of articular cartilage appearing anechoic in this area. It's important to be a little bit careful in the trochlear groove further distal. Sometimes you will get an very often you will get an irregular appearance just at that groove further distal, and that is actually normal.

And another view that you can do is to assess the distal patella in that area here. Now, as the blue box indicates, we're in a longitudinal plane, and looking at the patella on the left hand side of that bottom picture with no cartilage on top. And then we've got the medial trochleri with a nice bit of cartilage above that subchondral bone.

So this is a good view to assess the distal aspect of the patella, and again, you can go along the entire width of the patella. Right, what do we see when we get desmitis of the middle patellar ligament? It's not a very common condition, but it can sometimes be quite significant, difficult to deal with, and also not so easy to find because these horses don't always block to intra-articular diagnostic local anaesthesia of the scial joint.

And this was here, you can see a core lesion which is visible transversely and also longitudinally here on the longitudinal view with a loss of longitudinal fibre pattern and hypoeogenicity, and here you can see that hypoecogenic areas, very similar appearance to tendons. And you can also get sort of more punched out core lesions or very generalised damage to the middle patellar ligament, like in this case here, where the overall ligament is large, enlarged, and also the outlines of the middle patellar ligament are appearing very irregular. And you know, it's always good to compare left and right, but it's not unusual in horses that have, mm patellar ligament, dess or desmoopathy that, this could happen bilaterally.

So check out. The other side, and this was such a case for bilateral damage to the middle patellar ligament here with a very large area of hypoegogenicity that correlates to this area here with the loss of longitudinal fibre pattern and the same on the on the other leg. Osteochondral defects, really something important where ultrasonography can help us.

And again, in addition to radiography, it also may help to identify certain fragments and give the surgeons some more idea of, of its exact location. And here we've got two examples, two different horses, well, we've got some sort of mild to moderate pathology on the lateral trochlear ridge here with a thickening of the cartilage and a irregular disruption to the subchondral bone surface. And then we've got much more severe changes here in the image below where it's hard to recognise the, the anatomy here.

This is also a lateral trochlear ridge, with very severe changes and severe irregularities. This was a study that compared radiography and auto sonography for the diagnosis of OCD and the femoral patella joint. And what they found that they, the, the, the imaging modalities were then followed up by either arthroscopy or postmortem examinations.

And what they found was that ultrasonography actually had a higher sensitivity compared to radiography for the detection of OCD lesions, and that was particularly interesting in the medial trochlear ridge. So it's worth scan, scanning a youngster to see to further assess concerns over osteochondral lesions. OK, so we've done the medial approach, the cranial approach will now move over to the lateral approach.

That's sometimes a little bit harder, this area to assess, just because we've got a little bit more of soft tissue, in between the probe and the areas we are interested in. And then some horses, we may not get the best picture. So make sure you, you pick your patients wisely to begin with, and don't expect too much in the larger holes in terms of visualising deeper structures like the lateral meniscus.

So that's an area we can assess, the lateral collateral ligament, fairly easy to look at. We've got a view here into the, proximal part of the, that part of the femoral patella joint, which I want to show you because this is a nice approach that you can also use to for diagnostic local anaesthesia. And the lateral fematibial joint is usually only visible when there is distention and is otherwise, you cannot see that pouch.

Then we've also got the common tendon of the perineus tertius and the long dis to extends the muscles and that tendon sheath that communicates with the lateral fematial joint. And then we've also got the Prolitius tendon that might be of some interest. And looking at this area now, this is an image that is particularly nice, which is why I picked it for the presentation.

Unfortunately, you don't always get such a nice image of the natural meniscus, but in the right patients you do. And again, that's everything that applied to the, to the medialfe material joint also applies here and in The case, approximately here, you can see it's a normal joint and you can't see any joint fluid anywhere. Whereas on the bottom right here, we've got an image where we can see the pouch of the natural power tibial joint, and you can see that anechoic fluid between those light blue arrows.

Now, there's another area slightly deeper here, that's frequently confused with the lateral permitibial joint diffusion. But this is actually the politius tendon that's here scanned of incidence. And here are a couple of examples where you can see that or actually, first of all, sorry, this is actually a video showing a femmo patellar joint distention.

If you're not sure whether this is a true distention, sometimes it helps to apply some pressure here and you can see quite nicely. In this, in this video that when I apply the pressure, the joint gets smaller, and if I let, let go again, it gets bigger again. So this is, this is the same ho with that lateral fematibial joint effusion.

And here, we've got the meniscus again. But then the Politius is, as I say, commonly confused with the, with the distension, and here, that's because of the of incidence artefact. And this is the very same horse, and between the difference between the pictures left and right is that the probe is slightly still tilted.

So, and for the meniscus here, and this is the area where the politius sits. If you then tilt slightly the probe, the politius gets ecogenic and the meniscus gets hypoecogenic. And so this is really the best test.

If you're not sure if this fluid or not, make sure you tilt your probe. If it does become hypoecogenic. And you know you're dealing with the publiclius tendon.

So it's worth moving around and scanning these areas from slightly different angles to assess it fully. And this is here again in the video, just slightly tilting, tilting that probe and showing again that Politius tendon and not the joint distension. So this is the pouch of the femur patella joint, and this is the pouch I use for blocking the stifle, and you usually see some fluid in this joint, and the way you find it is you position your probe in the transverse plane over the lateral trochlear ridge.

And then you move over slightly to the lateral side, and this is the lateral trochlear ridge here. And in between those red arrows, you can see the out pouching of the femmo patella joint. That I would consider a normal amount of synovial fluid in here.

It's very common to see it that way. It's really important to get this picture to let go with the pro pressure. When you scan this and put too much pressure on, it's very easy to push the joint down and then you cannot detect it.

So when you're looking for it, make sure you let go with your probe and only apply as much pressure as needed to have sufficient contact. And then of course, this, this joint can also show signs of inflammation and synoviti with thickening of the joint capsule and also some synovial proliferation like in the picture at the bottom here. Then this is an area that's important to just be aware of, probably not so much to see pathology frequently, but we've got this common tendon of the peroneus tertius and the longest extensor muscles, and there's a tendon sheath which communicates with the lateral peritteral joint.

And it's worth assessing it for synovitis in this picture up here, you can see a contrast radiograph here where we have injected. Radioaque contrast medium into the tendon sheath, and you can see it communicates here with the lateral tibial joint quite clearly. And this is an important thing to remember for wounds.

This is a horse here that sustained the wound, actually quite far away, you should think from the stifle joint, from the lateral femotibuum, from the fema patella, but it was unfortunately too close to the lateral, to the, to the tendon sheath here and therefore, If you do get wounds on the lateral aspect, even if they're further down and especially if they are puncture wounds, maybe that even go a little bit further approximately, don't forget to, to also think of a possible, infection, of the, of the lateral femoidal joint, the stiho joint. We'll stop. Then moving on to the cranial approach, so now we've assessed the holes with the limb weight bearing, looked at the medial approach, the cranial and the lateral approach, and then now I would flex the limb.

And assess important structures there. So here you can have a really good look at the medial and lateral femo condyle and more importantly, at their weight-bearing surface as you have flexed the, the limb in this position. And then you can also assess the medial natural cranium meniscal ligaments and also the intercondylar eminence.

OK, so, and in this specimen here, you can see the, the, the, two images of the, of the two important structures here and at the top, we've got the proposition as indicated with the light blue box, and then you get the weight-bearing surface of the medial femo condyle and what you're looking for there is this nice and even smooth subchondral bone surface and an even parallel running . Anechoic area, which is the articular cartilage. And then if you change your proposition slightly, further down, and this image shows here the longitudinal view of, of the cranial meniscal ligament.

And some horses you can get such a lovely image. Now, as you can see in the specimen, this is a ligament that slightly runs on a sort of curved line, if you like. And it means also here, it's really important.

To visualise all areas and move your probe around and it's very easy to make this ligament look not so nice because you won't quite get it acagenic enough because you're not quite on incidents. And again, I've picked a nice example here and unfortunately sometimes you can't quite get that, that sort of image quality very much depending on the horse. There are also cruciate ligaments that you can see.

I personally don't scan those very frequently. This is obviously a sort of dislocated, specimen here just to visualise those structures. It's described that they can be assessed, I think, to get a diagnostic picture to decide whether there's pathology or not.

It's really, really hard and and certainly in my hands, at least, these are very difficult, ligaments to assess, but theoretically, it's been described and it's possible, and, it's certainly fun to, to give it a go and, and scan those. But as I say, to actually use this as a, as a diagnostic tool for, for the cruciate ligaments, I find, I find personally difficult. With the medial thyro condyle, it's important to swipe from medial to lateral, to make sure to assess the entire, weight-bearing surface, not to miss a lesion, and I also actually then turn from around and also assess the.

Assess the conduct in a transverse orientation. In order to get to the cranial meniscular ligament here, it's, you can, what you can do is you can basically visualise your, medialfemo condyle nicely, and then move all the way down until you get this picture, and this is again that cranium meniscal ligament here. You're in a transverse view.

You've just gone down distally now from your from your, from your femoral condyle. And then if you turn your probe here, 90 degrees, you then get on longitudinally and you get this, this image here. So this is the way to find it.

Follow the line down, it transvers you until you get this picture and then turn around 90 degrees. And this is here, the intercondylar eminence where the cranium menicule ligament attaches onto. Try the ligament here, here.

And if you then go a little bit further around towards medially, you can also then get a picture here of the medial meniscus, and this is showing the medial meniscus also with part of its ligament here. And this is again, your femoral condyle coming in. So this whole area can be assessed nicely.

In terms of pathology, that's a lot more common on the medial aspect, which is why I think it's most important to assess the medial aspect, but you can also visualise the same structures naturally. And this is an example here, of course with a very abnormal, very damaged cranial meniscular ligament. So, the cranium mellusar ligaments sitting here, that's a comparison to your normal.

You can also see that how irregular the surrounding tissues are, and then the longitudinal view, you can see that significant disruption here and that very irregular looking bone surface of the intercondylar eminence as well. So this is an example of a very abnormal case. And I think for that, the ultra ultrasound scan is, can be really useful and you can really visualise that area.

I think to, to look at some sort of mild or moderate changes of this ligament, I think sometimes, unfortunately, ultrasonography will not be good enough to, to, to, to visualise this area. And then here, I've got some examples of lesions in the medialfemo condys. We've got some subchondral cyst-like lesions here.

And what's interesting is that the ultrasound appearance always seems to be a lot more worrying than the radiograph. I mean, in this case, we've got a very large li lesion here visible, and this is actually that sort of crater that you can see here, the damage and the . Weight-bearing part of the condyle here looking onto the cartilage, and then this was the ultrasonographic appearance.

And what you're looking for in cyst-like lesions here is a clear disruption to the subchondral bone. And a lot of thickening of the articular cartilage. Sometimes you can see the bottom of the cyst, sometimes you can't.

And that's also very much depending on how deep and how, how, how large the cyst-like lesion is. And then here on this radiograph, what you can see is mainly just flattening of the femoral condyle. You could maybe, if you're really critical, say that there is maybe some regular density here, but you probably wouldn't, wouldn't be definite about sort of the, the, the joint surface damage.

You then can see how it looks like you can see some clear damage here off the surface and some softening of the cartilage in this area, which was very clear ultrasonographically. And instead of the cartilage being nice and unechoic, you, it gets more ecogenic and you can see also clear irregularity here in the subchondral bone. So very, very nice to see with ultrasonography.

And this is where we've looked at horses here to compare x-ray and auto sonography to assess for pathology in the medial femoral condyle and particularly subchondral bone changes and 28 horses were here included. They all underwent X-ray and ultrasound examination and then the images were anonymized and reviewed by an experienced clinician. The findings in the media.

Were graded on radiographs and on ultrasound images, and there was a significant difference between the two modalities and the detection of the lesions. In 7 out of 28 lesions, they would have been missed with only radiographic examinations. So there were 7 out of 28 horses in this group, where radiography didn't show a lesion, but ultrasonography did.

And these are just two examples of those. And I think that's particularly important as well and, and sort of where we take radiographs of the cipher with a portable machine and sometimes we all know that, maybe also the image quality might not be good. Enough, always, and it's hard to get a perfect picture.

Of course, we're all trying to get the perfect picture, but it's not always possible. I think these two images are of absolutely acceptable diagnostic quality. But when you put the ultrasound scanner here, you can see substantial lesion in this medial femo condyle.

And a clear subchondral bone damage and this irregular appearance of, of the articular cartilage and also here milder lesion, but again, still a lesion. And all you can really see here is maybe some slight flattening and here, not, not really very much. So, it's worth, scanning the medialfemo condyle and these sources, and I've made it a routine part, and if you've got the right block handy, it can be, it can be quite quick, quick, quick to do, and then certainly something to, to screen for.

Of course, this is also something you can use as for an ultrasound guided injection of a cyst like that. So, again, the laminar flex position, visualising that, that subchondral bone cyst, and then, under ultrasound guide. You can insert a needle and medicate the lesion with the corticosteroid.

Here, it's been found to be really important to get the corticosteroid into the synoval lining of the cyst. So you need to put quite a lot of pressure on with your needle and really try and push it underneath. It should be really hard to inject.

And otherwise, if you inject it just loosely, if you just put it in and inject it, it'll come straight out. So people have started doing it also under arthroscopic guidance, and you can see what else is going on in the joint. Or if that's not an option, you can still do it.

Here, in this case, this photo shows the injection done under general anaesthetic, which is really nice because then you've got time to position your needle and really put the pressure on. Also in youngsters that may not be handled enough. Tolerated.

But this is also possible in the standing, in, in, in a standing sedated horse. A lot of the times it makes sense to block the stifle joint beforehand. Horses with stifle pain don't like standing with the joint flex for a long time.

But, yeah, so it's also very possible to do it standing. Now, just the caudal approach, as I said, I've, I don't routinely scan saner joints from the caudal aspect and that's a personal preference. Of course, for completeness, I think it's important to be aware that it is an option and some people may, may use it more frequently than I do, but you can basically visualise the cahorn of the medial and lateral meniscus and The medial and lateral femoral condyles again and I just want to show you here how a possible image could look like.

So this is a really sort of a nice enough image and it's still probably not brilliant in terms of detecting subtle pathology. But it's good enough to, to recognise the structures here and for this, again, it's important to have a convex probe. These structures are, are quite deep.

It can be 5 to 20 centimetres deep depending on the type of force. And so what we can see. Have the pole positioned in again in a longitudinal plane, and then in red, we can see the medial remo condyle here.

In yellow you can see the medial meniscus. And then in green, you can visualise your proximal tibia. In terms of the role of ultra sonography for assessing cypher languages, I think it's important not to go and Ultrasound scans, for joints, and make diagnosis without doing anything else.

I think diagnostic local anaesthesia is really, really important, especially for the sort of mild to moderately lame horses and only the horses where you've got a really severe distension and a very severe pathology. You probably don't necessarily need to block those, but all the other sort of horses and sport horses that have a sort of mild to moderate, lameness that you suspect is, is, linked to pathology that you've seen on ultrasound, I think it's really important to also confirm the clinical significance of your findings with diagnostic local anaesthesia. And I think that ultrasonography is a very, very important part of our standard imaging modalities together with radiography.

And if I want to assess a stifle, I will make sure to X-ray and to ultrasound scan it. But then don't forget about the advanced imaging modalities that you may want to apply where you want to send the horse to your referral centre. And centigraphy is usually not as useful.

There are a lot of horses with stifle pain that will have an absolutely normal bone scan. CT, I think, can be really quite interesting and useful if, if, and, and so MRI if these advanced imaging modalities are available. But, also don't forget about arthroscopy.

If you are looking to fully assess the diaper joint, a lot of the times, we would combine. The standard imaging modalities, radiography and ultrasonography, together with arthroscopy, and to, to, to reach a diagnosis and a good idea what we're dealing with. And this is a study here from 2017 where this group has compared arthroscopy and ultrasonography for the identification of pathology in the equine stifle joint, and they found that ultrasound was better for the medial meniscal lesions.

It was also better to visualise osteophytes. And of course, it was the only way of visualising the patellar ligaments pathologies. Arthroscopy was superior in assessing the cranial meniscal ligament tears, and also, of course, to visualise the articular cartilage.

So I think each modality on its own has its limitation, and that's their conclusion from the paper, but this is also the conclusion comparing other modalities that we've got available. And that's obviously depending on the location and the type of the lesion, and I think again, the best results we get by, by combining those modalities. I like to summarise, we need a good anatomical knowledge and a very systematic approach for this type of joint ultrasonography.

I think it's got a very important role in assessing lane is localised to the type of joint. But of course, it's got its, limitation, combine all approaches and, don't forget to use ultrasound, assisted injections. So if you are looking for the, approach and try and get into a joint for a block, don't hesitate to utilise auto sonography to identify those, joint pouches.

And then also consider ultrasound-guided injections if you see horses with subchondral bone lesions in the medial fema conducts. OK. Thank you very much and I'm very happy to take some questions.

Carolyn, thank you so much for a very informative webinar and your graphics and explaining was unbelievably helpful. It it it just helps to correlate what we're looking at with where we're looking at it. So that was absolutely fabulous.

Thank you. Folks, we've got no questions coming through. If you do want to pose any questions, as I said to you in the beginning, just pop on the Q and A box and put a question through there.

But Caroline, I think you've done, such a fabulous job that you've really answered everything that, that one could think about, in, in the approach to that stifle. And, the, the multi-modal approach as you said, is really very, very important in these cases. Great.

Yes. Thank you. Right folks, so that's it for tonight.

Caroline, thank you for attending and thank you especially because you've been so rushed with your big move and everything else and it was really brilliant to have you on and we look forward to having you on another webinar in the future. Thank you so much, really enjoyed it. Thank you.

Folks, that's it for tonight, from my side and my controllers Dawn and Lewis in the background. Thanks to everybody and goodnight.