0:00

Case number three is not gonna be a case of a meniscal tear,

0:03

it's not gonna be a meniscal tear, there may be a meniscal tear

0:07

there, but that's not the reason why I'm showing you the case.

0:10

In fact, there is actually a meniscal tear here, but that's not why

0:12

I wanna show you the case. I wanna show you the case for

0:14

a different reason. I wanna start with the sagittal T1 as I always

0:19

do. I think it's very important to get into a habit

0:22

of looking at things. So I'm starting laterally. I'm already noticing that

0:26

there's a little bit of signal in the posterior and lateral tibia maybe

0:29

the anterior lateral femur there, okay, maybe... Yeah,

0:37

maybe some meniscal signal right here, but you wanna look at it on

0:40

a proton density or a T2 weighted, okay, so

0:43

there's something going on there. When I turn to the sagittal T2s.

0:48

Okay, and then look at the marrow. Oh, wow, okay, so I'm already

0:54

seeing marrow edema along the anterior lateral femoral condyle right here.

0:59

Posterior lateral tibial plateau. Okay, so these are likely microtubule

1:05

contusions that have occurred. If I go immediately, I'm also seeing Bone

1:08

Marrow Edema along the posterior medial tibial plateau.

1:12

So there are microtubule contusions, these are micro fracture in the bone.

1:16

Okay, that's what this is. And The patella overall looks okay.

1:21

So I wanna bring Ashley in here to ask question number

1:25

four. Okay, so based on this, what soft tissue structure is injured in

1:31

this patient that has bone marrow edema in both the anterior lateral femoral

1:34

condyle and the Posterior tibial plateau? Is it the ACL, the PCL,

1:39

the media collateral ligament, or the medial retinaculum, which soft tissue

1:42

structure is injured based on the marrow edema findings that you're seeing

1:46

here? Okay, so 89% of people got this correct, the ACL, the Anterior Cruciate

1:53

Ligament, that's exactly right. Okay, good. So this is a pivot shift injury,

1:57

this is a pivot shift injury when you get marrow edema along the

2:02

anterior lateral femoral condyle as in this case, in the posterior lateral

2:07

tibial plateau. That should ring alarms in your brain automatically, okay.

2:11

This is a pivot injury. The ACL will be torn in 100%

2:14

of cases. Okay. In every case that I've seen of this,

2:17

the ACLs has always been at least partially torn if not completely torn,

2:21

okay. This is a pivot shift injury, this happens in people like... Skiers

2:26

or American football players, okay. When a valgus load is applied to

2:31

a knee with a femur, either an internal rotation or the tibia in external

2:36

rotation. Right? So if the valgus load is applied to a flex knee,

2:41

where the femur is internally rotated or the tibia is externally rotated,

2:44

you get this pivot shift injury mechanism where you get

2:49

loading on the ACL and the ACL is pretty much torn. Okay. And

2:52

you get these microtubule contusions in these areas. Now I'm gonna show

2:55

you the ACL, just look at that. Look at this ACL it's thickened, there's

3:00

fluid transecting, the mid substance of it. It's just...

3:05

That's a complete rupture or a complete tear, you can't trace all the

3:09

fibers because you have this fluid discontinuity right here in the middle

3:13

of the tendon... Of the ligament, excuse me. So, this is a complete

3:18

tear of the ACL. With a Pivot shift mechanism with bone marrow microtubule

3:23

contusions along the anterior lateral femoral condyle, the Posterior lateral

3:27

tibial plateau. In fact, the reason why I'm showing you this case,

3:30

is that Bone Marrow Edema patterns in the knee are extremely,

3:34

extremely important. Okay. The Bone Marrow Edema patterns predict the soft

3:39

tissue structure that's injured. Okay, so if you get...

3:42

This is one of five marrow edema patterns that's recognized

3:46

as a classic pattern that predicts soft tissue, this is known as the pivot

3:50

shift mechanism of injury. When you get, if you get marrow edema of the

3:53

anterior lateral femoral Posterior lateral tibial plateau, the ACL is always

3:57

injured. There's four other classic contusions patterns that... I'm actually

4:04

gonna show one of them later on in this talk, but this is

4:07

the pivot shift mechanism of injury. And I wanna show you another

4:12

finding in this case, so this is the medial, and again,

4:14

notice that the posterior horn is double the size of the interior.

4:17

There is a little bit of signal here,

4:20

it's not really going to the inferior or the superiority that... So maybe

4:25

this slightly degenerative signal or equal degeneration within the meniscus

4:28

without the sweet terry. But as we come laterally... Look at the anterior

4:34

horn, the posterior horn, there is a little bit of signal here kinda going

4:37

to superior and the inferior surface there. Okay, it looks a little abnormal,

4:41

seen on two or three slices. If I go to the

4:45

coronal stars to focus on that lateral meniscus there...

4:53

Okay, so yeah, there's a signal here, this meniscus is torn,

4:57

there's a tear that the periphery of this... Of the

5:01

lateral meniscus, the posterior horn of the lateral meniscus. This is anteriorly

5:07

with a meniscus is attaching with a transversal ligament along with a tibial

5:09

root attachment, and then if we go posteriorly, it doesn't look that great.

5:14

This may involve the root, this maybe a root ligament here as well

5:17

on the posterior root about ligament. And you can see part of the...

5:21

It's sort of a complex tear, there's some signal here and there's some

5:23

signal there, so this lateral meniscus is not looking great, okay. So you

5:28

can see the nice microtubule contusions here along the lateral femoral condyle.

5:32

You wanna make sure there's no condyle defects. So this is the marrow,

5:38

this hypo intense dark line is the cortex, and this great intermedia signal

5:42

is the articular cartilage. So you wanna scrutinize this cartilage well,

5:45

I like looking at it at the coronal's the best, especially the medial lateral

5:49

femoral condyle, I think the coronals is the best. For patella department,

5:53

I think the axial is better to look at the articular cartilage,

5:56

you can see the cartilage better, but you wanna make sure that the

5:58

signal is preserved and it's nice and great. You start to see a fluid

6:01

signal, you know that there may be a defect in the cartilage can

6:04

be partial thickness, or if it involves the entire thickness of the cartilage.

6:07

It's a full thickness. Here, the cartilage actually looks relatively preserved.

6:11

When you have intermedia signal within that cartilage, there's debate whether

6:14

that's normal, that could be cartilage generation or early cartilage generation,

6:18

but here the lateral compartment cartilage, I think looks, okay. Okay,

6:22

you can actually also see the ACL, this is the ACL right here, look how

6:26

it's amorphous, it's not well defined, there's fluid all around it,

6:30

this is a torn ACL. The PCL on the other hand,

6:34

which is a dark hypo intense structure is preserved. I can see it

6:37

inserts extra articularly, about the proximal tibia, and If I trace it approximately,

6:42

I can see it inserting right there on the medial intercondylar notch, that's

6:45

a normal PCL, okay. Good, you can see here too look at this

6:52

fibular collateral, create one, maybe create two sprains of that fibular

6:56

collateral ligament approximately, okay. Other findings here as well.

7:03

Come back to the sagittal. We can again, take a look at these

7:10

here, there is probably a small joint effusion, this is more than just

7:14

physiologic, there's likely a small super patellar joint effusion. The quadriceps

7:20

tendon looks intact. The extensor magazine, the patellar tendon, I think

7:24

probably looks okay, there is a little bit of pre patella soft tissue

7:26

edema here, along the posterior joint capsule here. So those are all findings

7:31

that you wanna kinda take a look at, when you're reviewing a case

7:34

like this. Okay, so this is a pivot shift injury, they can be

7:38

associated with meniscal tears... Meniscal... Both medially and laterally.

7:40

In this case, we had a lateral meniscal tear, but the pivot shift

7:43

is, 100% of the time is associated with an ACL tear,

7:46

as we saw in this case. The Anterior Cruciate Ligament is torn. When

7:49

you have... The moral of the story, and this... The teaching point here

7:52

is that when you have marrow edema along the anterior lateral femoral condyle,

7:55

posterior lateral tibial plateau as in this case, the ACL is totally torn,

7:59

in those cases. Okay? Alright, good.