0:00

So here is the last set of cases.

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We're gonna cover everything that, uh,

0:06

we've talked about in the second half, including, um,

0:09

thator mechanism, pop teal, fossa,

0:11

and, uh, postoperative ligaments.

0:14

So here we go. First case.

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Um, so this is a young, uh, woman who presented

0:19

with a patella dislocation.

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So history known to us, not a diagnostic dilemma.

0:24

What's going on here? And, uh, this is a

0:28

outside MRI.

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So the reason why I came to, uh,

0:31

know about this case is our orthopedic surgeon, um,

0:34

always likes to go over, um, some of the MRIs, uh, with me

0:38

before he takes the patient to surgery.

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And I'll be a little bit disappointed to say this was read

0:44

by one of our residents who graduated from our program,

0:48

didn't do a musculoskeletal fellowship,

0:50

but here I'll reach you, uh, with the reports that findings

0:53

of recent lateral patella dislocation with ossie contusions

0:56

of the medial aspect of the patella

0:57

and lateral femoral condyle, complete tear of the MPFL

1:01

and beum, borderline trochlear dysplasia.

1:05

So it sounds pretty good, right?

1:06

Okay, well let's look at the images.

1:09

And certainly we can see that there is stigmata

1:13

of a recent lateral patella dislocation.

1:15

We have the telltale signs

1:17

of bone marrow edema at the peripheral aspect

1:20

of the lateral femoral condyle.

1:22

We also have additional bone marrow edema at the medial

1:25

aspect of the patella medial and infra medial.

1:30

And then of course, we wanna make sure we

1:32

evaluate the status, the medial patella femoral ligament.

1:36

And so we can follow it.

1:38

And I'll blow this up from the patella attachment.

1:40

So it looks pretty good, pretty good until we get

1:43

to the mid substance and then

1:45

always get to the femoral attachment.

1:46

It becomes very irregular.

1:47

There's edema in this location

1:49

and there's probably a concomitant injury

1:51

of the medial collateral ligament as well.

1:52

You can see that the medial collateral ligament indeed

1:54

is thickened as well.

1:56

We can, uh, corroborate this on, uh, coronal images.

2:03

You can see there's some thickening of the superficial MCL,

2:07

some increased intra ligamentous, uh, signal,

2:10

some per ligaments edema,

2:12

and probably some degree of injury

2:14

to the deep media meniscal femoral

2:15

ligament at its femoral attachment.

2:17

You can identify the deep medial meniscal tibial ligament in

2:20

this case is intact.

2:23

And as, uh, Dr.

2:25

Resnick showed us in his earlier lecture about the medial

2:28

supporting structures, you wanna look

2:30

for concomitant injuries to the opposite side of the knee

2:33

or the lateral femoral TIB department.

2:36

And we can see the, um, osseous, um, contusions, again,

2:40

the lateral aspect of the knee.

2:42

Some of this bone contusion may be from the

2:44

patella dislocation.

2:46

Uh, but more typically what we'll see is bone contusions

2:49

and sometimes osteochondral fractures

2:52

of the lateral femoral condyle.

2:54

So when you're interrogating this closely,

2:57

you wanna make sure you look at this cartilage

2:58

Surface. 'cause certainly

2:59

we've seen cases where, uh,

3:02

cartilage injuries are missed.

3:04

However, if we go back to the patella, of course, we need

3:08

to make sure that we look for cartilage injuries in this

3:11

location as well.

3:14

So, given that this is an outside study, they added, uh,

3:17

some additional sequences.

3:18

This is one that you may see.

3:20

This is an optional T two oblique

3:23

through the intercondylar notch.

3:24

More for looking at the anterior cruciate ligament,

3:27

which we can see actually looks pretty good here.

3:30

But in actuality,

3:31

this gave us a nice look at this cartilage injury at the

3:35

inferior aspect of the patella,

3:38

which was not mentioned in, uh, the report.

3:41

And now that we have identified a cartilage injury here,

3:44

I'll show you two on this coronal I image.

3:46

You can see that there's a nice defect here

3:48

in the, uh, patella.

3:50

Now that we've identified a chondral injury

3:52

and what appears to be missing cartilage,

3:55

then your next thing to look for is,

3:58

is there a choal fragment somewhere in the bottom?

4:01

And I know Dr. Resnick

4:02

and, uh, Dr. Chang had a whole discussion on whether we

4:05

would, should call things loose or not.

4:07

Um, certainly in the acute st stage, we could, uh,

4:10

entertain the fact that this is probably loose given

4:13

that this patient had their injury recently.

4:16

In chronic phases, you have to be a little bit careful

4:18

because these cartilage bodies can embed into the synovium

4:22

and become adherent.

4:24

But here we can see at the, uh, needle aspect

4:28

of the supra patella recess is what looks

4:30

to be a filling defect within this joint effusion.

4:34

And certainly if you window it,

4:35

you can see this joint effusion

4:37

probably has some blood products.

4:38

You can see a little bit of fluid level there.

4:40

But one thing about this, uh, that tells me

4:44

that this is cartilage body is when you look at cartilage

4:46

elsewhere in any joint,

4:48

it falls a very predictable signal intensity pattern from

4:53

the superficial layer of cartilage to the deep layer

4:55

of cartilage at the interface with the subcon bone plate.

4:59

Generally speaking, the more middle

5:01

and super superficial layers

5:03

of articular cartilage are brighter in signal intensity.

5:06

And as you go to the deep layers,

5:08

ultimately the calcified layer

5:09

and the subc chondral bone plate, it becomes darker

5:12

and the cartilage becomes even more dark

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with longer te sequences, which is why when to optimally

5:21

evaluate articular cartilage, it's better to have a PD

5:23

or intermediate weighted sequence.

5:26

If you go closer to T two,

5:28

then all the cartilage becomes relatively dark

5:31

and black, such that it becomes difficult to delineate

5:34

where cartilage ends

5:36

and where subc chondral bone plate begins.

5:38

But nevertheless, if you know what the, the architecture

5:42

and signal intensity of cartilage should look like,

5:44

you will immediately recognize

5:46

that this is probably the deep portion of that cartilage

5:50

that was originally attached

5:51

to the patella subcon bone plate.

5:53

And this would be the superficial layer.

5:56

So this is the, uh, the part of the case, um, that was, uh,

6:00

missed by our resident, but, um, no big deal.

6:03

We had reviewed it in person with the orthopedic surgeon.

6:07

And, um, I think you should also have these, uh,

6:11

arthroscopic images in your image stack.

6:14

And so here's looking at the intercon notch,

6:16

the anterior cruciate ligament,

6:18

and uh, here, uh,

6:20

there are retrieving the chondral fragment.

6:23

And if you look, this is the patella femoral compartment.

6:27

This bottom part would be the, um, trochlea,

6:30

the top part would be the patella.

6:31

So here indeed is the chondral defect at

6:35

that infra medial aspect of the patella.

6:37

And here is the, the specimen explanted from the knee.

6:42

And actually what I like about this case is if you sort of

6:46

rotate this image and maybe flip it a little bit,

6:51

you can kind of see it almost perfectly matches

6:55

the MRI here.

6:56

So a nice kind arthro arthroscopic, uh, correlate, uh, to

7:01

what we were seeing on the MRI.

7:04

So, um, at surgery, um, the,

7:07

the patient did have some asymmetric laxity of the, uh,

7:10

patella On exam, of course,

7:12

we found this loose chondral fragment.

7:15

I think it's also best on your MRI images

7:17

to at least give a rough estimate to the maximum dimension

7:21

of the cartilage lesion, particularly in if they're deciding

7:25

to do some sort of osteochondral graft procedure.

7:29

Sometimes these cartilage fragments, um, are too small

7:32

to reimplant, um, back in the native site.

7:36

So in this case, they removed the loose body.

7:38

They basically did a chondroplasty of that area

7:42

and did an allograft MPFL reconstruction.

7:44

They did not replace that cartilage body back

7:47

to its native location.