0:00

Okay, let's stay with our same theme.

0:04

So, usually with a hyperextension injury,

0:07

we often see fractures of the anterior

0:12

condyles and the anterior tibia.

0:18

Now, for those of you that are new to MRI,

0:20

T2 spin echo imaging,

0:22

long TR, long T imaging,

0:23

not very good for looking

0:25

at bone unless you fat suppress.

0:27

We do have a beautiful view of our intact linear,

0:31

ACL.

0:32

There's our more globular-looking PCL.

0:36

On the medial side, we've got the MCL,

0:39

predominantly the tibial collateral component.

0:44

Around back,

0:45

that becomes the oblique popliteal ligament.

0:49

We've got the popliteus tendon.

0:52

We've got the fibular collateral ligament.

0:54

We've got the biceps femoris tendon.

0:58

Then we also have the neurovascular bundle,

1:01

including the tibial nerve.

1:02

Taking off from it,

1:03

the common perineal nerve.

1:06

We should really have about a two thirds,

1:09

one third relationship between the lateral

1:12

facet and the medial facet.

1:14

We do.

1:15

It should be smooth and non undulated.

1:17

It is.

1:18

We should have a trochlear groove.

1:22

We do.

1:23

And we should inspect

1:24

the medial patellofemoral ligament

1:26

and see its continuity with its crossing

1:30

of the adductor tubercle region.

1:32

We do.

1:33

So, so far, we've come up with very little.

1:36

Let's look at the sagittal and stay

1:38

with our continued search pattern.

1:43

On the lateral side,

1:44

we have the popliteus origin and tendon.

1:47

This time,

1:48

we do have an intact popliteofibular ligament.

1:51

We have a nice, clean arcuate.

1:54

Let's go over to the medial side.

1:56

The meniscocapsular reflection is normal.

1:59

The meniscus is normal.

2:00

We have a posterior triangle

2:02

and an anterior triangle.

2:03

On the lateral side,

2:05

the triangles don't hang together

2:07

as in discoid lateral meniscus.

2:08

They separate very nicely.

2:11

We've got open femoral growth plates

2:13

starting to close.

2:15

The tibial growth plate is closing.

2:18

That's a little premature for a 15-year-old,

2:21

so he's not going to grow a lot more.

2:23

And then, we've got a bone injury.

2:26

So, let's talk about bone injuries.

2:30

The lowest grade of bone injury is a contusion.

2:34

Now,

2:34

don't confuse a contusion with that giant

2:40

impact fracture I showed you earlier.

2:42

In a contusion, especially a low grade contusion,

2:48

you can see the architecture and the weight

2:52

bearing trabecular through the contusion.

2:55

When you have an impact fracture,

2:57

all you see are these little speckles of fat.

3:00

The fat basically implodes.

3:03

So, this is different.

3:04

This is a much lower grade injury

3:06

than we saw before.

3:07

And then, you have to start to look for lines.

3:10

And we do have a discrete line right here.

3:13

So we have a fracture.

3:16

It communicates with the cortex.

3:19

It breaks the cortex.

3:21

You can see it going right through the cortex,

3:23

but that is unlikely on a planar image to be seen.

3:26

So, fractures that are dominant in the medullary cavity,

3:31

the enchondral cavity,

3:32

the spongy bone cavity.

3:34

And I call them enchondral bone fractures.

3:37

I'll often refer to them as microtubecular

3:40

fractures, or enchondral bone fractures,

3:43

unlikely to be seen on conventional radiography.

3:46

Putting the clinician on notice that the plane film

3:48

in their office is likely to be negative.

3:51

But it's still a fracture.

3:53

These do very well.

3:54

They don't take as long as these obvious

3:57

transcortical fractures that we see on x-ray.

4:00

Even though the cortex is involved,

4:02

it's invisible on x-ray.

4:05

They usually get better in about three to four weeks.

4:08

But you have to use the fracture word.

4:10

I don't mind if you say microtubecular fracture.

4:13

I don't mind if you say enchondral, spongy,

4:16

or medullary bone fracture.

4:18

You say where it is,

4:19

you say how big it is,

4:21

and then you use all your conventional

4:22

radiographic tools.

4:24

Gapping, none.

4:25

Depression, none.

4:27

Angulation, none.

4:29

Comminution, none,

4:30

and so on.

4:32

This is an isolated finding

4:34

in this part of the knee.

4:35

There is one other incidental

4:36

finding in this child.

4:38

He's got some swelling of the proximal patellar

4:42

tendon at the tenuous margin.

4:44

And this would be jumper's knee.

4:46

So, your conclusion would read

4:48

hyperextension related,

4:51

intramedullary bone fracture

4:54

or microtrabecular fracture without complication,

4:59

comminution or depression.

5:01

Period.

5:02

Next paragraph.

5:04

Proximal patellar tendon

5:07

inflammation consistent with mild jumpers knee.