0:01

So this was a seven year old girl who presents with knee pain.

0:06

So now the age group is completely different,

0:08

so your differentials are going to be different, and, um,

0:12

you don't have history of trauma. So whatever we see, we know that it's, it's,

0:16

it's not, um, an injury. Um, so you have to think of, um,

0:20

causes other than injury. So again, you can start from the medial side. Um,

0:25

and again, young patients, um,

0:27

seven year old when we are not expected to have a lot of degenerative changes

0:31

to. So, um, um, have a quick look at the menisci.

0:37

Um, I don't know if it'll be very hard to assess for articular cartilage here on

0:40

these images. And that's the posterior cruciate ligament.

0:45

Anterior cruciate ligament. We know there is a big joint effusion.

0:51

And then what we see here, um, is, uh, a, a,

0:55

a subc chondral cyst or almost like an erosion with peri, um,

1:00

mar edema around it.

1:02

You see that fluid extending into that subc control, uh, cystic area.

1:09

That's another, uh, important finding here. The extens,

1:14

some mechanism looks okay.

1:19

Again,

1:20

the appearance is different because these patients have unfused growth plates.

1:27

No, I have a question.

1:29

Yeah.

1:30

Um,

1:31

I think the key to this diagnosis was picking up the synovitis at which I didn't

1:35

see. Um, can you just point out where the best place to see synovitis is and,

1:39

um, and the, the best sequences.

1:43

So best sequences to pick up synovitis are going to be of fluid sensitive

1:47

sequences. Any fluid sensitive sequence, um, uh,

1:49

should show synovitis and synovitis is this joint effusion. And, uh,

1:53

when you start seeing this gray stuff in the joint that's,

1:57

you see that so fluid, like if it's simple joint fluid,

2:01

it should be completely clear. Um, uniform T two hyperintense signal.

2:05

But you see that gray stuff, uh, within the joint fluid. All this,

2:09

this is your, this is your synovitis right here, right there, there.

2:16

So it should be clear fluid if it's simple joint,

2:18

but you start seeing that almost like debris in the joint,

2:21

which is attached to the joint lining. Um,

2:25

in some areas you can see it like little frondy growth. So that's,

2:28

that's synovitis. So you see that, um, this thing, this area here.

2:33

So it's, it's, it's not simple clear joint fluid. Uh,

2:40

you can look at the axial images too.

2:43

This is a proton density sequence. Again,

2:47

if you see it's more of a gray signal here,

2:50

rather than T two bright signal here, that means this is not simple joint fluid.

2:54

There's a lot of synovitis. All that has a little gray signal.

2:59

You see that? So,

3:00

so you how see how we transitioned into clear fluid from this great tissue,

3:05

I think axial is showing it much better. So all that this,

3:08

all this is synovitis.

3:15

Okay, then we are looking at everything else. We look at the extensor mechanism.

3:18

Patella looks okay. Um,

3:21

the medial and lateral re macular looks okay.

3:24

Posterior structures are fine. So the two big findings here are,

3:29

uh, big joint effusion with synovitis. Um,

3:33

there's not too much of soft tissue edema around it.

3:35

So all these things suggest that it's a somewhat a chronic process.

3:38

And then we saw erosion. So in, in this age group,

3:42

you have a little chronic, um, joint effusion within erosion,

3:46

you'll think of inflammatory arthropathy,

3:48

and in this case you're thinking of juvenile, um, inflammatory arthropathy.

3:53

Um, to think of differentials,

3:56

I mean obviously a big joint effusion with nothing else.

3:59

You'll think of septic arthritis,

4:00

but you should have that history that the patient had this red, hot,

4:03

swollen joint, uh, some labs to, uh, support it.

4:06

Elevated E SR CRP white count. Um,

4:10

and and another thing with septic arthritis is, uh,

4:13

in a very early stage when there is joint effusion,

4:15

but you'll still see a lot of, uh, like, um, the,

4:18

the soft tissues around it are going to be inflamed.

4:20

You'll see a little bit of subc chondral edema from that infected joint fluid.

4:25

So you have other signs on imaging that can tell you that that effusion.

4:29

It's probably from septic arthritis. And obviously once it's little advanced,

4:32

you'll start seeing destruction of the articular cartilage and marrow changes or

4:36

sub subc chondral, uh, bone changes. So doesn't look like septic arthritis.

4:41

There's no history of trauma. So we're not thinking of trauma.

4:45

Inflammatory will be top one or differential, uh, diagnosis.

4:50

Um, sometimes, um, I mean in this age group, hemophilic arthropathy, uh,

4:54

but again, the patient has history of hemophilia,

4:56

they have history of recurrent, um, uh, joint effusions,

5:00

and then that fluid is not going to be like it. It'll have some ev uh,

5:04

evidence of because that, that's hemorrhage within the joint.

5:07

So we'll have some evidence of hemorrhage within the joint that can be seen on,

5:11

on fluid sensitive. We'll start saying hemosiderin staining along the joint,

5:15

like really dark, um, uh, signal along the,

5:19

the joint line. Um, that is, that,

5:23

that will start blooming of if you have any gradient sequence right now.

5:26

Let me see if I have a gradient sequence. Um, I if I,

5:29

if you don't have your gradient sequence in the protocol,

5:32

and if you wanna look for blooming your localizers are your best sequences.

5:36

So all the localizers are typically gradient sequences. So, uh,

5:39

if you wanna look for any blooming, you can, uh, yeah,

5:45

uh, these localizers have just few images, not in any, okay.

5:50

So, uh, um, hemosiderin staining that will suggest, uh, uh,

5:55

hemophilia. Um,

5:57

and then in advanced cases you have articular surface destruction.

6:02

So this was a case of juvenile, um, rheumatoid arthritis,

6:07

given that there was joint effusion and a, a small erosion that we picked up.

6:13

Even if we can't give a specific diagnosis, we can say that okay,

6:16

there's a big joint effusion and then, uh, basically we can recommend, uh,

6:21

like, um,

6:22

they'll do an as joint aspirations in this fluid for analysis and run all

6:27

the tests on them.

6:31

Uh, in the absence of any clinical history, can we differentiate mm-hmm.

6:35

And inflammatory like al arthritis compared to an early septic

6:39

arthritis?

6:41

Yeah, that's what I said, right? Even if we, uh, I mean, um, uh,

6:46

suppose we didn't have history, but uh, by the time they do mr they've also,

6:50

like you often, like you will have some labs, um,

6:53

like elevated E-S-R-C-R-P and white count with, uh,

6:57

that leftward shift and that white count that suggests presence of infection.

7:01

Um, on imaging, I told you, uh, there would be more, uh,

7:05

edema in the surrounding soft tissues. Like if you see here, the subcu fat, um,

7:10

has no inflammation, no edema,

7:12

and the subc chondral bone has no edema. Whereas in septic arthritis,

7:16

you'll have some edema in the, around the, in the surrounding muscles,

7:21

in the subcutaneous soft tissues and in the subc chondral bone,

7:24

because this is infected fluid, so it makes structures around it very angry.

7:28

There's a lot of inflammation in the surrounding structures also,

7:31

so you'll always find edema. So that's, I think that's one of the, um,

7:37

uh, a good science to, um, think of septic arthritis on imaging.

7:42

But, uh, the final diagnosis is with tissue. Like, I mean, uh, fluid analysis.

7:46

They have to aspirate the joint and if the white count and the joint are more

7:49

than 50,000, and that's when, uh, they establish a diagnosis of septic and,

7:54

um, cultures will be even, um, better.

7:58

But then you have to wait for four or five days for the results to come out.

8:01

And then the culture will tell you the organism and antibiotic susceptibility

8:05

for the, for better treatment.