How you doing? My name is Ryan Hubbard and we'll be doing an ultrasound consult of the onocollateral ligament of the elbow and looking at normal as well as what you see when there is a tear in the ligament. The onocollateral ligament is made up of three bundles. The bundle we're chiefly concerned with is the anterior bundle of the onocollateral ligament as this is the major stabilizer of the medial elbow. To find this bundle, the most important aspect of that is patient positioning. I tend to position the patient supine with the arm externally rotated and the elbow flexed or side-lying on the affected side with the medial elbow exposed upwards. Once they're in position, the best way to find the ligament is to anchor the proximal end of the probe onto the medial epicondyle and then perform a sweeping motion, anterior and posterior, until you bring the onocollateral ligament anterior band into view as it courses from the medial epicondyle and attaches down to the sublime tubercle. We'll see this on the next slide. Here we see a picture of the medial elbow at the onocollateral ligament. We are using a high-frequency linear transducer to look at the onocollateral ligament at the medial elbow in this picture. You see here the onocollateral ligament coming off of the medial epicondyle and it is typically the deep 50% to 30% of the common flexor tendon. You see it coursing over top of the humeral ulna joint and attaching at the sublime tubercle. The fibers here are linear and look normal. This is what you should expect to see with a normal UCL with the fibular architecture and the linear fiber is going in the same direction. No areas of hypoechogenicity. That would suggest a tear or a defect in the tendon and it's very homogeneous and that's exactly what you should be looking for when you're looking at this tendon in normal. On the right hand picture is actually a stress view of the UCL. In this view we typically anchor the medial or proximal end of the probe at the medial epicondyle and you want to get a good view of the UCL and then you can use either the table or your leg as a fulcrum and put a valgus stress on the medial elbow similar to the milking maneuver to see if you see any gapping at the humeral ulna joint or any defects in the tendon that pop up when you are actually doing the stress. I tell people that typically the easiest way to do this is to actually use a video or a cine clip to perform the valgus stress and then go back and do the measurements for the gapping at the humeral ulna joint using the video opposed to trying to do it in real time which can be fairly challenging. What you're looking for is any more than two millimeters of gapping at the humeral ulna joint or greater than one millimeter of gapping compared to the contralateral side of the humeral ulna joint. Both those would be suggestive of UCL pathology. You see here the contralateral elbow which is the affected side. This is the same view as our previous picture just on the right elbow opposed to the left so everything's flipped so the medial epicondyle is now on the right hand side of the screen. You see here very well off the bat there's a defect in the ligament here in the mid substance. We lost that normal good-looking fibular architecture with the linear fibers coming from the medial epicondyle and attaching down the sublime tubercle. The fibers are now thickened. They look heterogeneous opposed to homogeneous and they have areas of hypoecogenicity which also suggests thickening and issues with the ligament. We can see here with larger tears the tears can be seen just at rest. You see here depicted the tear there in the mid substance of the ligament just above the humeral ulna joint. This is a mid substance tear and a very common area to get tears in the UCL and again the big ones you can even see at rest without doing the stress. On the right hand side of the picture this is actually a valgus stress of the UCL just like we did previously. Here on this stress view you see that there is more gapping than the previous picture. You also see a little bit of fluid extravasating up from the humeral ulna joint just deep to the UCL and then when we did these measurements which are not on here the non-stress side was about a millimeter whereas on the right hand side when we stressed the elbow it gapped to about three and a half millimeters. As we said the cutoff is two millimeters of gapping so this would be suggestive of a tear. If you didn't see one at rest this would be suggestive of a tear in the ligament where significant laxity in the ligament. Other things you can see like I said are bubbles coming up through the humeral ulna joint and this is also suggestive of instability of the ligament so we would consider this a complete tear of the ulnar collateral ligament at the mid substance with moderate dynamic instability. And that completes our ultrasound consult of the UCL at the elbow. Thank you.

3rd Edition, CASE 15

3rd Edition

Elbow and Forearm

ulnar collateral ligament

elbow ultrasound

UCL tears

milking maneuver

dynamic instability