0:00

Let's take a look at this adolescent

0:01

male with open growth plates.

0:04

So probably about 12 or 13 years of age,

0:07

and this patient has had an anterior

0:10

cruciate ligament graft.

0:12

See if we can figure out where the graft came from.

0:14

Perhaps we have to turn to the axial

0:16

to see if there is a graft harvest site.

0:20

And there is not.

0:21

So most likely,

0:23

this graft came from hamstring.

0:26

You know,

0:26

semimembranosus, semitendinosus,

0:28

or one of the hamstring group.

0:30

And in the axial projection,

0:32

we're able to see the femoral tunnel

0:34

and follow it into the knee notch.

0:36

And now, we'll turn our attention

0:38

to the sagittal projection.

0:41

But I do use the axial and axial oblique

0:43

to look inside the tunnels.

0:45

Looking inside the tibial tunnel,

0:47

you should probably be struck

0:48

by the sheer size of the tunnel,

0:51

relative to what's in it.

0:53

There's an eensy teensy little object

0:56

in the middle of a sea of higher signal.

1:00

That is problematic.

1:01

So, let's drill into it a little further.

1:04

We've got, on the left,

1:05

in the blue corner,

1:07

the T1 weighted fat weighted image.

1:09

In the middle,

1:10

the overrated but sometimes useful T2 weighted image.

1:15

And on the right, in the red corner,

1:18

we've got the water weighted, fat-suppressed image

1:21

or water-emphasized image.

1:23

So let's start out with the red corner,

1:27

the sensitive image.

1:29

And I'm sure you all are struck by the edema

1:32

in the tibia.

1:34

You might say, well, okay,

1:35

they drilled through the tibia.

1:36

Why shouldn't there be any edema?

1:38

That's true,

1:39

but they also drilled through the femur.

1:41

So, why isn't there edema in the femur if this

1:44

is just physiologic from the surgery?

1:47

So, that's not very logical.

1:50

We have another issue to comment on,

1:55

and we'll have to do that very diplomatically.

1:57

They drilled through an open growth plate

2:01

and they have

2:03

what looks like a bioresorbable structure

2:06

through the growth plate.

2:08

So potentially, inciting premature closure.

2:11

Although that probably isn't going

2:13

to go into our report,

2:14

but we'll have to diplomatically word this.

2:17

How might we word it?

2:18

We might say something like bioresorbable object

2:23

or bioresorbable anchor,

2:26

intratibial emplacement that crosses the tibial fisus.

2:30

And then, we're going to go on to make some other

2:32

descriptors that are coming very shortly.

2:35

Now, let's look at where they put the femoral tunnel.

2:37

We want that tunnel to be at the intersection

2:40

between Blumensaat's line, which is right here,

2:43

and the posterior femoral line.

2:45

So if we follow across,

2:47

right there is where our femoral tunnel

2:50

should be going in, and it is.

2:52

Very close to the cortex.

2:54

Very brave, very proper,

2:55

very appropriate.

2:57

The tibial tunnel, it's a little posterior.

3:01

I like them to be about 2 cm forward

3:04

with the standard roof anatomy,

3:07

this one's probably a little under 2 cm.

3:09

So, it's placed a little bit backwards.

3:11

But we have another problem.

3:13

You can look at any of these sagittals you want.

3:15

Let's scroll them and see if you can

3:17

figure out the other problem.

3:19

One quick scroll and you should have figured

3:21

out by now that the tibia is going west.

3:26

The tibia is going to your left passively,

3:29

with the patient lying on their back.

3:31

Tibia going to California,

3:32

tibia going to Portugal,

3:34

tibia going to Perth.

3:36

It's going west the wrong way

3:39

in somebody that should have a graph that keeps it

3:42

more posterior.

3:44

So, if you drop a line on either

3:46

the medial or lateral side,

3:47

in fact, I'll make my line with my color line.

3:50

You should have no more than

3:52

5 mm of space here or less.

3:55

We've got almost 2 cm of space.

3:58

Let's go over to the lateral side.

4:02

Oh, it's forward too.

4:04

We drop another line on the lateral side,

4:06

ad we've got passive anterior tibial translation.

4:09

No doubt.

4:10

So, we've got automatically graft failure.

4:14

Now, we have to define the failure.

4:16

What happened?

4:18

So let's look at all three images,

4:21

the T1 first.

4:23

Lots of swelling.

4:25

And what might strike you is this.

4:29

Follow very carefully.

4:30

I'm going to make it a little bigger

4:32

and a little tighter.

4:34

Follow very carefully these fibers.

4:37

Look where some of the fibers are going.

4:40

They're sweeping over the top of the tunnel.

4:44

They should be plunging into the tunnel,

4:47

but they're not.

4:48

They're going towards this object right here,

4:51

which is obviously some surgical iatrogenic object

4:57

because it has an artifact associated with it.

5:00

So, something has pulled off and taken some

5:05

of the ACL fibers with it, if not all.

5:09

Let's look at the sagittal T2

5:11

and really kind of tease out the case.

5:13

Are there any fibers at all inside this tunnel?

5:17

And the answer is yes, there are,

5:19

right there.

5:20

These straight darker fibers.

5:23

Here they are right here on the water-weighted

5:26

proton density fat sat image.

5:29

And we saw these in the axial projection,

5:31

our little dark object in a soup of high signal,

5:35

but we've got too much high signal.

5:39

Not only do we have too much high

5:40

signal around these fibers,

5:42

but we also have too much high signal in the tibia.

5:45

So, what's going on?

5:47

We've got inflammatory synovial tissue

5:52

that has prolapsed into this tunnel

5:55

and is auto digesting the tunnel.

5:57

Look at the tunnel.

5:58

It is massive compared to the size of

6:03

the graft and the graft anchor.

6:05

In fact, where is the graft?

6:07

It's this little, tiny, squiggly thing here.

6:10

So, we've got the phenomenon

6:12

of tunnel osteolysis,

6:16

which is often a byproduct of synovial tissue

6:20

that is dissected into the tunnel,

6:22

which, by the way, is more common

6:24

when you resect the native anterior cruciate ligament.

6:28

We do not have that same issue

6:30

in the femoral region,

6:32

and our diagnosis is further supported by this

6:35

reactive, extensive edema throughout the tibia.

6:40

Now, let's go back to that position

6:43

of the fibers that we were talking about.

6:45

The fibers look like they're going

6:47

in the right direction here.

6:49

They're plunging towards the hole

6:51

that was made by the surgeon,

6:53

but not these.

6:55

These are making a detour.

6:57

They're going to the left.

6:59

The viewer's left.

7:01

They're going towards the west coast,

7:03

and they are attached to this susceptibility

7:07

artifact right here,

7:09

as we already pointed out on the T1 weighted image.

7:12

So, something has pulled out.

7:14

Perhaps some sutures have pulled out

7:16

with the fibers of the ACL.

7:20

There is failure of the tibial tunnel with osteolysis.

7:24

There is overall graft failure.

7:26

This graft cannot be saved with physical therapy.

7:30

Unfortunately, at this very young age,

7:33

this child is going to have to have a redo.

7:36

Let's look at the coronal projection,

7:39

because I think it really drives

7:43

home the osteolysis phenomenon.

7:45

We'll make them a little bigger.

7:47

Look at your low signal anchor.

7:50

Very few fibers are discerned within the tunnel.

7:53

Here are a few right here.

7:54

But look how big

7:56

the tunnel is filled with synovium

7:58

relative to the structures within it.

8:01

And, of course,

8:02

illustrated is the crossing of the growth plate,

8:06

which we would like to avoid at all costs

8:09

in most cases.

8:11

How about the menisci?

8:12

Well, it's a child.

8:13

You don't get meniscal tears too often in a child.

8:16

Doesn't have any.

8:17

So, the menisci are just fine.

8:19

The cartilage surfaces on the

8:21

T1 weighted image coronally are just fine.

8:24

And the case is really about graft failure.

8:28

So, in a companion vignette,

8:30

you saw a cyclops lesion with no passive translation.

8:34

In this vignette,

8:36

you've seen graft failure,

8:38

no cyclops lesion,

8:40

or maybe a little bit of synovial thickening

8:43

right there.

8:44

So maybe be a small cyclops lesion,

8:47

but graft failure with passive anterior tibial

8:51

translation and the phenomenon of tunnel lysis

8:55

or perigraft synovitis in the tibial tunnel,

8:59

auto digesting the bone and further

9:01

contributing to graft failure.

9:05

Let's look at another one, shall we?