0:00

Which brings us to the final point, we're gonna return

0:04

to those bone bruises or bone contusions.

0:08

And a number of years ago, we identified

0:10

that when you look at them closely, be it with ct,

0:14

or particularly with mr, in addition to hemorrhage

0:18

and edema, you may see little collections

0:22

of fat globules often surrounded by a rim

0:27

of slightly higher signal intensity shown here,

0:31

an inflammatory reaction.

0:34

So it was our belief that

0:35

what we were looking at was fat necrosis.

0:39

Now example, a bone contusion involving the distal femur

0:43

with these fat globules surrounded by a ring

0:48

of what may be an inflammatory reaction.

0:52

A beautiful example here

0:54

with a contusion involving the fourth metacarpal bone

0:58

shown by radiographs CT and by Mr.

1:01

Look at the globules here.

1:03

All right, remarkable with the marrow edema.

1:07

So you can see that with these bone contusions,

1:10

and you see it with fractures as well,

1:12

particularly those about the knee, shoulder, and hip.

1:17

Here, an example of an osteochondral displaced osteochondral

1:21

fracture involving the proximal tibia, comminuted in type,

1:26

and the arrow pointing to globules of fat

1:29

with some other tissue around them.

1:32

So we can come together with this pathogenesis

1:36

that we have a bone injury, we have hemorrhage

1:39

and edema within the fatty marrow.

1:42

We have necrosis and death of fat cells.

1:45

We release the fat,

1:46

and we form these oil cysts that migrate away from the

1:52

original area in injury, surrounded by

1:57

a rim of composed uh, uh, inflammation

2:01

with macrophages

2:03

and giant cells of variable size

2:07

as they migrate away from the point of injury.

2:10

And you could imagine then something like this,

2:13

if you're dealing with a massive fracture,

2:16

that those globules may enter the vascular str uh stream.

2:21

And because of that with massive fractures, you may end up

2:25

with distant fat embolization here, an example

2:28

of fat emboli within the retinal vessels.

2:33

So what I've done in my allotted period of time,

2:36

I've emphasized the pathogenesis

2:39

and proper terminology of a variety of injuries

2:42

that involve the articular surfaces.

2:45

We started with the cartilage, talking about particularly

2:49

fissuring fibrillation and delamination.

2:53

We moved on to chondral fractures, osteochondral fractures,

2:57

subc chondral fractures,

2:59

And we have talked about bone contusions,

3:04

introducing another feature, fat globules in addition

3:08

to the hemorrhage and edema.

3:11

And with that, we have finished this particular lecture.