Hi, my name is Zach Bailowitz. I'm a sports medicine physician at Kaiser Permanente in Oakland, California, and today we'll be doing an ultrasound consult on muscle injury patterns. This topic is important because muscle injuries account for about one-third of all sports-related trauma. MRI is currently the gold standard, but ultrasound utilization has been increasing, and this is because it is a dynamic modality that can be portable and allows us to monitor injury progression by looking at these injuries in multiple different time frames. There have been many classification systems that have been used in the past to describe muscle injuries. The Munich Consensus Statement was the first to break things up into indirect versus direct muscle injury, and this will be important in our case, thinking about whether or not this is more of a strain pattern or more of a contusion or direct trauma. The BAMIC, or British Athletics Muscle Injury Classification, is probably the most widely used classification system, and it has a letter and a number system that denotes not only the severity of the tear, but also the location of the tear, and this can be important in classifying, but also in prognosticating these injuries. This is a nice graphic that describes the BAMIC classification system, and what you can see here is that it's outlining whether or not this is something that's more of a myofascial injury here, whether or not this is something that's a muscular tendinous injury here, or whether this is a tendinous injury, and as you can see, the healing time, depending on the location of the injury, can vary. So let's dive right in. This is a normal abdominal musculature on ultrasound. We're looking kind of exactly in the midline, and so here you can see, and sorry, I tried to color-code the boxes to correspond with what you see down here, so you can see kind of up higher toward the umbilicus. You can see the rectus abdominis on both sides with this nice fascial band down the middle that separates the two. As we go further distally towards the pubic symphysis, you see the rectus abdominis grows a little bit larger, and then you do have some smaller muscles here called the pyramidalis that most athletes will have, and then here's a longitudinal or long axis view that looks down as it is attaching onto the pubic symphysis, and you see the rectus abdominis here, and then the pyramidalis muscle down further. As we go off to the side, you will see the oblique muscles here, so you've got three layers, the external oblique, the internal oblique, which is typically the largest, and then the transversus abdominis, which is the deepest musculature there in the kind of lateral abdominal wall. One thing we do notice here is that there is a small nerve that lives in this space. Typically this is where the ilioinguinal and or iliohypogastric nerves will run, and that'll be important when thinking about some different pathology we can run into. So when we're looking at acute tears, this is an example of a quadriceps tear. You see a large anechoic region here. This is an example of a hematoma, and here that hematoma is just adjacent to the central tendon of the rectus femoris, but not involving it, so this would be a musculotendinous injury, whereas this is a nice video to demonstrate what looks more like a myofascial injury with normal muscle architecture here, but then here you've got disruption of the muscle with kind of this fuzziness, haziness, the loss of normal muscle architecture, so this is more of a lower grade or myofascial injury. In the adductors, this is a nice example of, you see adductor longus, brevis, and magnus, and what we see is as we go distal down the thigh, we start to see the adductor longus open up with a large hematoma, and the reason that this diagram here is important is because it shows the proximity of the hematoma to the neurovasculature, and this patient was having numbness and tingling in their anterior medial thigh, and this can be because of compression of the neurovasculature. So here we'll start by going distally, you start to see a very large hematoma as we travel down, and this is a nice long axis view of it here. Some injuries are not as subtle, this is what's called the T-junction tear in the hamstring, and you just see this small hypoechoic region right at the junction between the short and the long heads of the biceps femoris, and as we watch the sinaloop here, we'll see a relatively small region, small disruption there, but it is big enough to be causing symptoms for this patient. In more chronic injuries, we'll see hyperechoic fibrosis or scarring within the muscle, so you can see that in long and short axis. This is not an injury that occurred recently, but something that probably happened anywhere from 6 to 12 months ago, and again, we're seeing this kind of brighter signal, there's no hypoechoic regions that would indicate more of an acute tear. Now these are all in contrast to a direct muscle injury or contusion. Here you can see this kind of mixed hyperechoic, hypoechoic mixture of clearly disrupted muscle fiber. We're looking here in the short axis, and then here's the long axis view, and this looks quite a bit different from our indirect muscle injuries that we were seeing earlier. Now if these contusions are not recognized earlier, one of the consequences can be myositis esophagans, so this is a nice example of here a vasus intermedius contusion, you can still see some surrounding mixed hypo and hyperechogenicity of the muscle fibers, but then you see this large hyperechoic line here with posterior acoustic shadowing consistent with calcification, and if we watch the sinal loop here, again, you see normal muscle, now we start to see abnormalities, and then there's these large calcifications here, and that's consistent with myositis esophagans.

3rd Edition, Case 01

3rd Edition

Abdomen

ultrasound techniques

muscle injuries

Munich Consensus

BAMIC

myositis ossificans