Dr. William Palmer from the Massachusetts General Hospital in Boston. He's a musculoskeletal radiologist, and he's been very generous with his time. Rather than having one long imaging lecture, he's been able to break it up so it corresponds more closely with the lecture material, so we thank him for that, and this has always been a highlight of the course. Good afternoon. I'm going to take very selected topics in the elbow, the wrist, and the hand, starting off with the elbow and focusing on the medial ulnar collateral ligament, and specifically the anterior band, and the abnormalities that I'll show on MRI can reflect either an overuse situation or an acute injury, in which case there is usually a complete disruption with soft tissue edema or hemorrhage. First, let's look at some normal anatomy, and this is a coronal image, and it shows this is after an orthographic injection. This is the ulna, the region of the sublime tubercle, and then the ulnar collateral ligament coming up, and it's thin where it attaches to the sublime tubercle, and then normally it will fan out into several fascicles as it approaches the medial epicondyle. The sublime tubercle is almost always seen easily on axial images, and once you've identified that, then you can follow the UCL up from that location to where it is fanning out and attaching to the medial epicondyle. You can also see this intimate relationship with the flexor digitorum superficialis, which is a dynamic stabilizer of this passive UCL. This is a different patient, a veteran pitcher, and you can see here that the UCL is much thicker than in the normal situation, and in this additional pitcher, it's very, very thick but continuous from one attachment site to the other, and then here you can see a little bit of fluid that's undercutting the ligament at the sublime tubercle attachment site, the so-called T-sign indicating a combination of adaptive change and partial tear. Here there's been an acute injury, and all that's left of the UCL is this little low signal area and some high signal that's undercutting it, so it's partially torn at the sublime tubercle attachment site, but it's otherwise completely blown out, a little bit like an ACL in the knee where the visualized fibers are very few. And it's pretty common to have acute injury on top of chronic injury. This radiograph shows an ossicle here on the medial side of the elbow, and it could reflect old heterotopic ossification due to a ligament injury. It also could reflect a small avulsion from the apophysis back when the kid was in Little League. So there are signs of chronic change, and here in the setting of the acute injury on the T1-weighted image where the marrow is bright, you can see this ossicle and the ligament coming down towards the sublime tubercle. This is also T1-weighted, but because it's an orthographic study, it's fat suppressed. So the high signal contrast that's in the joint in the setting of the acute tear is leaking out at the attachment site of the ligament to the sublime tubercle, and then there is this extra articular leak into the flexor pronator mass because the capsule is yet to seal up. So that's an acute superimposed on chronic. Sublime tubercle fractures can occur, and this is the left and right elbow in this individual showing a fracture involving the sublime tubercle. And then on MR images, the ligament is essentially normal, but it's followed down to this fracture fragment which still is partially undercut by high signal on the T2-weighted sequence indicating incomplete bony bridging. Presumably, it's that fracture with displacement and healing that can result in this kind of an appearance on the radiograph, this prominent bony proliferation at the sublime tubercle. So next I'm going to turn to dislocation, and many of these aspects of elbow dislocation were already discussed this morning. And again, I'm going to emphasize the simple dislocation. This first example is somebody who fell on an outstretched hand during a basketball injury. And what I'm going to show you first are the post-reduction images, X-ray and CT, followed by the pre-reduction MRI to emphasize the reason for the extensive soft tissue injury. The radiographs are essentially normal alignment. There is a joint effusion. And the point of this CT is to demonstrate that there are no fractures. So here, radiocapitular compartment and no fracture of the radial head. And we go a little bit more medial, no fracture of the coronoid process, and perfect alignment. But here's the pre-reduction MRI. So this is in the sagittal plane, and we have T1-weighted images here, and then this fat-suppressed T2-weighted sequence. So T1-weighted images, excellent for assessment of bone marrow and identifying fractures. The T2 with fat suppression shows extensive fluid, edema, hemorrhage, and ligament discontinuity. So here is the proximal radius and the lateral ulnar collateral ligament. And then it's discontinuous and very irregular in contour in this location. Another slice over, we're starting to see an impaction injury. So the bone marrow contusion here involving the capitellum due to impaction or load by the radial head, which is otherwise normal. Large hemarthrosis, extensive periarticular edema or hemorrhage. And then we work our way over to the coronoid process, which is normal. But here is the region of the brachialis. And so the brachialis muscle, in part because it's draped over the humeral head at the time of distal humerus, at the time of dislocation, undergoes a profound injury. We'll see that again on the axials. But first, the coronal images. This is what's left of the ulnar collateral ligament. So it's a little bit of a nubbin. And now we're starting to see lateral ulnar collateral ligament, radial head, normal alignment of the proximal radial ulnar joint. And then here, discontinuity of the lateral ulnar collateral ligament. And then the impaction injury involving the capitellum due to the radial head. This is meant to emphasize the degree of soft tissue injury, which can occur without any fracture after a dislocation. So distal humerus. And this is some biceps, which is rarely injured, and triceps as well at the time of dislocation. But this is all that's left of brachialis. And so this extensive injury is at least in part the explanation for some of the heterotopic bone that might be seen following a dislocation. This is the median nerve. Here's the brachial artery. And they're in the breeze, completely surrounded by that large area of hemorrhage. So the terrible triad was addressed this morning. And this next example is to emphasize the difference in difficulty in identifying small fracture fragments on MRI compared to CT. So your go-to examination, if you're concerned about small fracture fragments, is really the CT examination. Proton density axial. This is T2-weighted, fat-suppressed axial. And the radial head here shows bone marrow edema and some flattened contour. And the coronoid process shows this fracture line. And unless you're looking for that very, very specifically, it's extremely difficult to identify. And there is a small degree of diastasis. This is a gradient echo image. Gradient echo images are great for identifying small acidic fragments in the joint, loose bodies for example, and fracture fragments as well. And this is the coronoid process fracture fragment. This is the disruption of the lateral ulnar collateral ligament with a mild radiocapitellar alignment abnormality. On the sagittal images, clearly there's an alignment abnormality. And this is as well as the coronoid fracture fragment is seen with a degree of diastasis. And it looks like any of the other soft tissues to my eye. There's just a little bit of blunting of this coronoid process. The radial head here, this is the fracture line, the fracture fragment, the bone marrow edema, the malalignment. So much easier on CT. You can see that the fracture is comminuted. It's much larger than I would have guessed based on the MRI. It's displaced from its donor site at the coronoid process. And then here is the fracture and the fracture fragment. Again larger than I would have guessed based on the MRI. So the go-to modality for these fracture fragments is CT. So I'm gonna look at ulnar-sided risk to problems and then some ligament injury as well. So first of all the TFCC. Degenerative tears, centrally located, the traumatic tears, the ones that are symptomatic and important tend to be more peripheral. First some normal anatomy. And this is a normal scapholunate ligament. And it can be smooth in some locations and irregular in others. And it goes from one cartilage surface to another. So don't confuse articular cartilage, which can be high in signal intensity, especially on these gradient echo type sequences as a defect in the ligament. Likewise here, here is a lunotriquetral ligament. And this is the volar aspect of the TFCC and then the ulnotriquetral ligament. And as we scroll through these multiple images, this is a normal appearing TFCC. So smooth, proximal, and distal contours. And then you can follow that out to the peripheral tissue. And the important areas to look are the fovea, as mentioned in the previous talk, where the radial ulnar ligaments attach. And then also this is the meniscal homolog, which then is followed over to the ulnar styloid process and causes the avulsion at the time of distal radial fracture. And then the meniscal homolog also can be followed up to where it becomes ulnar collateral ligament next to the ECU tendon. This is one of our MR technologists, no symptoms. We were testing a protocol. And she has a small perforation of her TFCC cartilage of her disc. And just an age-related phenomenon. In contrast, here's a hockey player. He was thought to have a stable distal radial ulnar joint, but he has this profound abnormality involving the disc. So this is a large enough defect that you have to think, okay, a piece is missing and it's become displaced somewhere. The peripheral tissue, however, is also abnormal and there is a separation or disruption at the junction between the disc and then this peripheral stabilizing tissue. As I come more volar, here's the fragment, the donor site, and then the TFCC fragment displaced in the distal radial ulnar joint. So this person, because of the stable DRG, simply went on to an arthroscopic debridement. In contrast, here's an individual who fell playing basketball and was thought clinically to have an unstable distal radial ulnar joint. He noticed that his disc is intact on the T2 and then here on the gradient echo image. There are all kinds of variable thicknesses of the TFCC. This one is attenuated, but it's normal. And then we head out to the fovea, where the radial ulnar ligament should be attaching. And instead of the ligament complex, we are seeing this focal fluid. And then likewise, there's disruption of the homolog tissue, where it should be attaching to the ulnar styloid process. So an example of a peripheral tissue tear in a person with unstable distal radial ulnar joint and went to arthroscopy for a repair. Now here's a T2-weighted image and a gradient echo image. And it's an individual with a scaphoid fracture with negative radiographs. So the T2-weighted image shows this area of bone marrow contusion. It's hard to see a discrete line. Gradient echo images are not good for bone marrow evaluation. Fracture lines are always best seen on T1-weighted images. So although the fat-suppressed T2 is great for contusions, T1-weighted images do the best job showing fractures. This individual also has a tear of the scapholunate ligament. This central tear of the TFC may be old, may be new, may not be related to this traumatic injury. Same individual. Here's the fracture line. 37-year-old, history of remote injury in a recent fall. And the radiographs show an abnormal alignment between the scaphoid and the lunate, approximating 90 degrees. So greater than the normal range, 30 to 60 degrees. Now here's the same individual. T1-weighted images, great for bone marrow, which looks normal in this case. And there's clearly widening, but the ligament is otherwise very difficult to evaluate. So you have to go to this T2-weighted image, and it shows the ligament is in repose between the scaphoid and the lunate. Same individual. In fact, the same individual with the radiographs, showing that you can calculate those angles using separate MR sagittal images as well. So taking the lunate alignment with the scaphoid and coming up with the same 90 degrees. Stress views I think can be very, very valuable. They're used by the hand and wrist surgeons at MGH to show here an asymmetry in the degree of widening of the scapholunate interosseous interval, indicating or corroborating the instability and then the subsequent internal fixation. So my last topic then, I'm going to address a few things related to the thumb and specifically the ulnar collateral ligament. This, by the way, is the actual photograph that occurred in the first article on Gamekeeper's Thumb. So the UCL is comprised of both proper and accessory ligaments and an overlying adductor pollicis aponeurosis. So what I want to point out first is that the ligaments are not actually in the coronal plane and so therefore you do not expect to see them on a single coronal MR image. And although the diagrams frequently depict the ligament like this, in fact that can be confusing on an MRI because it'll make it look as if there's a tear of the UCL when in fact it's normal. So the proper, the accessory attaches in part to the volar plate and in part to the sesamoid. So this is a normal gradient echo coronal showing the radial collateral ligament and here the ulnar collateral ligament at the attachment site to the base of the proximal phalanx. And then on these sequential five images, you can follow that proper ligament finally down to where it attaches to the metacarpal head. So you have to look at sequential coronal images in order to see the entire ligament and then here is some of the aponeurosis overlying the UCL proper. So there's overuse, that's the gamekeepers, but what we're gonna see mostly is the acute injury, the so-called skier's thumb and then I'll emphasize the center lesion in the next two examples. So here are coronal images, they're T1 weighted and then this is T2 weighted as well. And this is the medial sesamoid and then therefore this is the accessory UCL and that's intact in this particular case. When the accessory's intact, it's very unlikely to have a volar plate injury. It's when the accessory ligament is torn that then you usually have or might actually have an associated volar plate injury. This is where you expect to see the ligament proper and it is missing. And here is the adductor aponeurosis and then here is the UCL proper and notice that it's at 90 degrees. So this is the classic center lesion which is also very well seen on sagittal images. So the first MCP alignment is normal and then as we head off more medially, we're starting to see this vertically oriented UCL ligament pathognomonic appearance on a sagittal image. And then here finally, coronal images, T1 weighted, T2 with fat suppression showing edema involving the tissues adjacent to the UCL here and then the adductor aponeurosis. This is a subtotal tear or rupture of the ulnar collateral ligament but it's not a classic stentor because it is at least partially underlying the adductor aponeurosis. And I thank you for your attention.

elbow imaging

wrist imaging

hand imaging

ulnar collateral ligament

triangular fibrocartilage complex