0:00

All right. So the first question that I see here is,

0:03

"Are you interested in patella alta and baja?" Yeah, I am.

0:06

I mean, the bottom line is that I think that patella alta can

0:11

be a clue for patella maltracking, especially young people that have patellar

0:14

maltracking disorders. So if there's a high riding patella,

0:19

meaning that the Insall Salvati ratio is increased by more than 1.2,

0:22

right? If you measure the longest axis of the patella on the sagittal plane,

0:27

and if you come to the mid sagittal cut and you do the

0:29

longest axis between the tibia tubercle and the inferior pole patella;

0:32

if you divide those two numbers and it's more than 1.2,

0:35

that's evidence that there's patella alta. And if there's other findings

0:37

like patella tendinopathy, Edema Superolateral Hoffa's fat pad, that suggests

0:42

that there could be a patellar maltracking disorder. Okay? So I am... And

0:47

patella baja is when you have a low lying patella, which I don't

0:50

think is as clinically relevant, but sometimes that can be an issue as

0:54

well. Okay? What's the mechanism for a Wrisberg rip tear? Okay. I'm not

1:02

a hundred... I think... Those are usually post traumatic. I don't know the

1:05

exact mechanism, so I don't wanna black pearl you guys. Okay?

1:09

I'm not a 100% sure, but you're talking about the Ligament of Wrisberg and

1:14

Ligament of Humphrey, right? So the Ligament of Wrisberg is that ligament

1:17

that runs posterior to the cruciate ligaments, and they're the meniscofemoral

1:22

ligaments. So it's like a tear along the very periphery

1:26

where that ligament attaches. Usually they're post traumatic. They can be

1:29

associated with joint capsule injuries. But I don't know the exact mechanism,

1:35

so I don't wanna black pearl anyone here.

1:37

How do we measure TT TG for patella maltracking and tilt? We can

1:40

do that. Now, what I'm about to tell you is something that isn't

1:43

followed by all musculoskeletal radiologists. So I wanna put that in there

1:47

already. Okay? So I actually don't use TT TG on MRIs because there

1:51

are studies that show that it's not as accurate as CT.

1:56

So I actually only measure TT TG, tibial tubercle trochlear groove distance,

2:03

on a CT examination. Now, some of my own colleagues at University of

2:07

Maryland do do this on MRI. So again, there's a wide spectrum of

2:10

people that think differently about this, but I personally don't measure

2:13

this on an MRI examination. 'Cause I've found when I've corroborated with

2:18

my orthopedic surgeons that we don't do a good job with quantifying this.

2:23

But again, different people feel differently, right? But obviously we know

2:26

that the TT TG, if it's between 1, 1.5, 1.52, it's

2:32

more in line than more than 2, it's evidence of patella maltracking. I use

2:36

the criteria that I just showed you, patellar Edema Superoleteral Hoffa's

2:40

fat pad, patella tendinopathy, patella alta. And I also use the trochlear

2:44

sulcus angle, which is a objective way you can test that there's now tracking.

2:49

So the normally trochlear sulcus angle, if you measure it, if you measure

2:53

the angle... If you go... If you triangulate your sagittal image,

2:58

you go to the anterior horn of the lateral meniscus, you measure 3 centimeters

3:00

above the anterior horn of the lateral meniscus and triangulate that

3:04

with the trochlear at the patellofemoral joint space, you measure the angle

3:08

of the trochlear; it should normally be about 138 plus or minus six. So

3:14

it should go from anywhere from 132 degrees to 144 degrees.

3:18

So if it's outside of that realm, that's objective evidence that there could

3:21

be patellar maltracking. So that's actually, that's the way I measure it,

3:24

by using the trochlear sulcus angle. I measure 3 centimeters above the anterior

3:29

horn of the lateral meniscus. I triangulate that with the axial image of

3:33

trochlear, and I measure the angle that's formed along the trochlear groove.

3:39

And that should be 138 degrees plus or minus six. So anywhere from

3:42

132 144. If it falls outside of that realm,

3:46

I suggest that that there could be... That's subjective evidence that there

3:49

could be patellar maltracking. I hope that satisfied your question.

3:54

Are there other questions that I can help answer? Anyone at all have

3:59

any questions about any of the cases that I showed?

4:02

Again, bone marrow edema patterns, hugely important, right? Bone marrow

4:06

edema patterns predict the soft... We actually talked... I showed you two

4:10

of them. And we talked about two of them. So I showed you

4:12

the acute patellar dislocation relocation. I showed you the pivot shift

4:15

injury. We talked about the hyperextension and the dashboard injury. The

4:20

one that I didn't mention was the clip injury. A clip injury is when

4:24

you have marrow edema along both condyles, the medial femoral condyle and

4:28

the lateral femoral condyle. When you start see microtrabecular contusion

4:31

along the medial femoral condyle and the lateral femoral condyle, that's

4:34

always associated with an ACL and MCL tear. ACL plus MCL.

4:40

Okay? So that's the fifth type of classic bone marrow contusion pattern

4:45

where the bone marrow contusion patterns predict the soft tissue structure

4:49

that's injured. So just to review, since there's no questions, the pivot

4:53

shift injury is when you have marrow edema along the anterior lateral femoral

4:57

condyle, posterior lateral tibial plateau. And the soft tissue structure

5:00

that's injured is the ACL, right? The acute patellar dislocation relocation,

5:04

which is the second type, is when you have marrow edema along the anterior

5:07

lateral femoral condyle and inferior medial patellar, and the soft tissue

5:11

structure that's injured is the medial retinaculum. That's number two, right?

5:14

The third type is the hyper extension injury, where you have marrow edema

5:18

along the anterior proximal tibia, anterior distal femur, and then both

5:23

the ACL and the PCL are injured. Those are the soft tissue structures that

5:26

are injured. That's number three. Number four is a dashboard injury where

5:29

you have only marrow edema along the anterior proximal tibia. That's your

5:33

microtrabecular contusion. And the soft tissue structure that's injured

5:35

is the PCL. And then finally, the fifth one is a clip injury

5:40

where you have marrow edema along the femoral condyles, the medial femoral

5:45

condyle and the lateral femoral condyle, and the soft tissue structure that's

5:48

injured is the ACL and the MCL. Okay? And I just wanna say

5:52

a thing about meniscal tears 'cause I think meniscal tears are very confusing.

5:56

We kinda classify them based on their orientation, right? So

6:00

it's either gonna be horizontal or vertical based on whether they are running

6:05

parallel or perpendicular to the tibial plateau. If they're parallel to

6:08

the tibial plateau, that's a horizontal meniscal tear. If it's vertical

6:13

to the... Or, I mean, excuse me. If it's perpendicular to the tibial plateau,

6:18

it's a vertical tear. Vertical tears have other types. You can have a

6:22

vertical longitudinal tear, you can have a vertical radial tear, you can

6:26

have a vertical oblique tear, right? So a vertical longitudinal tear is

6:29

one that's perpendicular to the tibial plateau, but parallel to the long

6:34

axis of the meniscus. Parallel to the long... That's a vertical longitudinal

6:38

tear. That's a tear that I showed you, that's the last case that

6:40

I showed you, right? That vertical longitudinal tear. A vertical radial

6:44

tear, which was the second case that I showed you, is a vertical

6:48

tear because it's perpendicular to the tibial plateau, but it's also perpendicular

6:54

to the long axis of the meniscus. That's what makes it a radial

6:57

tear. And that's why it's different than a vertical longitudinal tear. A

7:01

vertical oblique tear is also perpendicular to the tibial plateau, but it

7:05

sort of runs obliquely with respect to the long axis of the meniscus on

7:08

an axial image, right? It kind of runs obliquely, the Parrot beak tear.

7:12

That's an oblique tear. Okay? And then a complex tear is a combination

7:16

of a vertical and a horizontal, or a combination of different types.

7:19

Okay? So that... I hope that gives some clarification to meniscal...

7:25

How we classify meniscal tears. So I wanted to show you guys five

7:28

high yield cases of bone marrow contusion patterns and how they predict

7:33

soft tissue structures and also meniscal tears. Because I find that to be

7:37

very complicated for residents to understand, even my fellows to understand

7:41

and, quite frankly, even attendings, we... There's five Muslim gospel attendings

7:46

at University of Maryland, and we kind of describe meniscal tears somewhat

7:49

differently. So there is consensus based on things that have been published

7:53

in AJR and things like that. But that's, I think... The understanding that

7:57

I just bestowed upon you guys is, I think,

8:00

the mainstream understanding of meniscal pathology and meniscal tear and

8:07

how we describe it. Any questions for me?

8:13

Man, the last time I did this, or when I did the noon

8:15

conference, there were like... I couldn't even get through all the questions,

8:18

and now there's only two questions, so that's great. That's fantastic.

8:20

Well, I appreciate that. If there's no other questions, I'm happy to end

8:25

one or two minutes. Please feel free to email me if you have

8:29

any questions. Okay? I'm gonna put my email in the chat here.

8:33

If you have any questions about any of the content here today, I'm

8:35

happy to answer questions. It's been a real pleasure and honor

8:39

to give this talk today. And thank you to Dr. Collins,

8:43

Ashley and Paul for allowing me to speak on challenging MSK MRI cases.

8:49

Thank you so much.