0:00

<v ->A chondral fracture, okay,

0:04

is defined as a fracture isolated

0:07

to articular cartilage that does not extend through

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the subchondral bone plate.

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It's often characterized by sharp

0:16

straight line.

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So if I were gonna describe this case

0:20

since I did before, we saw this,

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it's an osteochondral injury

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manifest as a chondral fracture measuring

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or producing a chondral defect

0:32

measuring whatever we would do our measurements,

0:35

with an intact subchondral bone plate

0:38

and subjacent bone contusion.

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That would be my description of this particular finding.

0:46

This different, no light bulb,

0:48

This is a chondral injury manifest as chondral fracture

0:54

leading to a full thickness chondral defect,

0:58

measuring whatever with fairly sharp peripheral margin

1:03

with an intact subchondral bone plate

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and no subjacent marrow contusion.

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That's how I would describe this case.

1:13

Now the differential diagnosis

1:15

of traumatic chondral defects

1:17

as I've mentioned earlier in this course

1:20

degenerative defects but typically with those,

1:23

we are dealing with a sloping,

1:26

a gradual sloping margin at the edge of the defect.

1:32

An osteochondral fracture

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is defined as a fracture

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that extends through the articulate cartilage

1:40

violates the subchondral bone plate

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extends into the subchondral bone

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and may reverse itself and come out in a similar fashion.

1:52

Not always but possible.

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I pick a good one.

1:55

It has a name it's called a hoffa's fracture.

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It is an isolated coronal fracture of a single condyle.

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You can see it here and here and here.

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And the reason it's important because it's a single condyle

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you often do not see it well

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with conventional radiography.

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Even in the lateral view because the other condyle

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being normal

2:21

obscures this pathologic finding.

2:24

So related to axial compression on a flexed knee.

2:29

Now there are some classic osteochondral fractures

2:32

that we see

2:34

in patients with disruption

2:37

of the anterior cruciate ligament.

2:39

We all know to look for a deep notch,

2:43

okay.

2:44

Sometimes greater than one but certainly

2:47

greater than two millimeters in depth.

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But a long notch has similar significance.

2:54

Unfortunately, there's no established measurement

2:57

for a notch that is too long.

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A double notch is never normal.

3:04

We see this pattern osteochondral fractures

3:07

in the immature skeleton.

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And typically the fracture is the posterior notch.

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In those cases, that's the one that will show

3:18

the marrow edema.

3:20

So a small notch in this area is normal,

3:22

but if it's deep, it's long, or if it is double,

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it is not normal

3:28

and strong evidence of an ACL tear, but don't stop there.

3:32

Look for the wrinkled tibia.

3:35

This depression of the subchondral bone plate

3:38

that is seen in the posterior aspect

3:41

of the lateral tibial plateau.

3:44

Very common in patients who have tears

3:47

of the anterior cruciate ligament.

3:50

So let's go ahead and compare

3:52

osteochondral fracture and chondral fracture.

3:56

They differ in the age of the person,

3:59

as you can see.

4:00

The nature of the effusion.

4:03

With an osteochondral fracture both fat and blood,

4:06

non-blood with a chondral fracture.

4:10

They differ whether or not you're gonna see it

4:12

with conventional radiographs, yes.

4:15

The answer with osteochondral fractures

4:18

know the answer with chondral fractures.

4:22

They differ in healing potential.

4:24

Better when the bone is involved

4:26

hence better when there's an osteochondral fracture

4:31

compared to a chondral fracture.

4:33

A subchondral fracture is defined as a fracture

4:37

that extends through the subchondral bone

4:41

in a linear or curvilinear fashion without violation

4:46

or depression of the subchondral bone plate.

4:49

So here's an example of it.

4:51

The subchondral bone plate appears intact.

4:54

There is a bone contusion around it.

4:57

But as you look at this you can understand

4:59

why we might run into, sorry

5:01

might run into difficulties of differential because

5:06

osteochondral fractures can look similar

5:09

but they generally have curved edges

5:12

as they extend backup toward the articular cartilage.