0:00

This is a 22-year-old man with knee pain.

0:03

He's had prior ACL surgery.

0:07

They can either perform this surgery

0:09

using some hamstring,

0:11

they can use patella,

0:13

or they can use cadaveric tendon.

0:16

And this patient,

0:17

you can tell right away from the axial projection,

0:19

there's a defect in the anterior patella.

0:21

So they have used bone, tendon bone,

0:25

the other piece of bone coming from the tibia or

0:27

an autograft to make this new ACl for this

0:31

patient. Now, there are some advantages of this,

0:34

namely the longevity of the graft as opposed to,

0:38

say, cadaver, which may last a little less time,

0:40

but the recovery period is a lot easier when

0:43

you use cadaveric, non native acl.

0:46

As I scroll up and down,

0:47

this patient's got a small effusion and quite a

0:51

bit of scarring anteriorly or low signal

0:53

intensity in the axial projection.

0:55

And you can see the graft as this linear structure

0:59

along the lateral aspect of the femoral notch.

1:01

And the femoral notch is fairly generous in its

1:05

breadth or diameter from side to side or width.

1:09

let's look at the sagittal projection.

1:14

And one of the things I do in somebody that's had

1:17

an autographed is I look at the character

1:21

of the patellar mechanism,

1:22

because when you harvest tendon from the patella

1:26

and then take a strip of tendon down to the tibia,

1:29

the patella will often overgrow,

1:32

it'll get too big,

1:33

and sometimes that leads to patellar tendinopathy.

1:36

That is one of the complications of using

1:39

a bone tendon, bone autographed,

1:41

or a piece of patellar tendon.

1:42

And this patient actually has it.

1:44

They weren't born with a pointy inferior patella.

1:48

Now, that may not be problematic today,

1:50

but that can be problematic in the future.

1:53

And that's one of the reasons why I personally

1:55

would go for a cadaveric graft at my age,

1:58

and many people would.

2:00

The quadriceps tendon usually

2:04

isn't affected in patients that are harvested

2:07

because the harvesting usually occurs right

2:09

about here and then the strip comes down.

2:12

The other thing I like to look at is the character

2:15

of the patellar tendon. And admittedly,

2:18

it's a little hazy. It's a little thickened,

2:20

but there's no focal tear on

2:22

the water weighted image.

2:23

There's a little bright signal

2:25

right under that spur. Again,

2:27

the patient isn't symptomatic there yet.

2:29

There's also a little bit of signal intensity

2:32

at the patellar tendon insertion.

2:33

And I would comment on that

2:35

in the body of the report,

2:38

and there's extensive scarring at the site

2:41

where the clinician has entered the knee.

2:45

Now,

2:46

another caveat when you're looking at patellar

2:50

harvesting is to look at the length of the

2:53

patellar tendon, because it can contract.

2:57

And this is one of the causes of patella baja.

2:59

In other words,

3:00

a patella that's pulled down from scarring

3:03

of the infra patellar tendon.

3:04

And this one is a little bit short.

3:07

I like to see the length of the patella and the

3:11

length of the patellar tendon about one to one.

3:13

And just eyeballing it,

3:15

I think you would all agree that the patella

3:18

is substantially longer than the tendon.

3:21

So you would say that there is a tendency

3:24

for patella baja in this patient.

3:27

But let's move on to our graft.

3:30

Now, there are a few ways to look at the graft.

3:32

the conventional way would just simply be to do

3:35

your standard orthogonal views and hope you catch

3:38

the graft correctly, which, by the way, we did.

3:41

Another way to do it would be to look at the graft

3:44

and then angle with the graft distally, and then,

3:47

if necessary,

3:48

make a second angle along the femoral tunnel so

3:52

that you can see the intra tunnel portion or

3:56

the intraskeletal portion of the graft.

3:58

You only need to really do that in complex cases

4:02

where there's definite graft laxity.

4:05

This patient had pain but not locking

4:08

and not any known instability.

4:10

Or you may have to do it as part of an

4:12

add on or bring back examination.

4:14

Another technique that you might use,

4:17

especially in difficult cases where there's

4:19

extensive swelling, scarring,

4:21

and the graft is hard to really discern,

4:23

is you might take an axial oblique that's

4:26

perpendicular to the graft, like that,

4:29

so that you can see the graft in cross section and

4:33

assess its overall diameter from top to bottom.

4:37

Now, let's take away this line,

4:39

and let's look at where our

4:40

graph should be placed.

4:42

Our graft should be placed as close as humanly

4:45

possible to this line right here,

4:48

which is the posterior femoral line.

4:50

So we bring that line down,

4:52

and then at the intersection between

4:54

that line and Blumenstadt's line,

4:57

which is going to be right here,

4:58

that's where as close to the cortex as possible,

5:02

the femoral tunnel entrance should be drilled,

5:05

which takes a fair amount of courage and talent,

5:08

because you are right subcortical,

5:11

you're right next to the cortex.

5:13

So a lot of nervous nellies may take that hole

5:16

and put it too far forward or too far down.

5:19

And that is a lot worse than moving

5:22

the tibial tunnel around.

5:24

This is the more important of the tunnel

5:27

entrances. Now, the tibial tunnel,

5:29

I give a fair amount of latitude to that tunnel.

5:32

I like to see the tunnel a little further back.

5:35

If the roof is very vertical,

5:37

I like to see it forward a bit.

5:39

If the roof were very horizontal.

5:41

What do I mean by a horizontal roof?

5:42

It goes this way, our roof is going this way.

5:45

A vertical roof would go this way.

5:47

So I might put my tibial tunnel back a little bit

5:50

with the vertical roofs so it doesn't get bumped.

5:53

Now,

5:54

another thing I also like to do in looking at my

5:56

graft is look at this distance right here.

5:58

I like to have about a centimeter between the

6:01

graft and the femur when the patient is lying

6:03

on their back. Now, think about this.

6:06

If a patient is lying on their back and this piece

6:09

of bone is already touching the

6:11

trampoline of the graft,

6:13

imagine what happens to the graft

6:15

when they're standing up. Bang.

6:17

It gets slammed every time they jump or run.

6:20

So that is a little pearl,

6:23

a little nugget that is not often discussed that

6:26

you can take away from this brief talk.

6:29

Now,

6:30

I'm sure a lot of you are honing in

6:32

on this structure right here,

6:33

which we'll discuss in a minute,

6:34

but let's just go back to the

6:35

tibial tunnel for a minute.

6:37

I usually take the center of the PCL

6:39

and the center of the tunnel,

6:41

and I like it to be about 2 cm.

6:43

Beta has already stated there's a little bit of

6:46

variability and flexibility here depending

6:49

upon the femoral roof. Now,

6:51

let's go to this structure

6:53

that is a round mass anterior to the Acl.

6:58

It's ill defined on the T1 because it's buried in

7:02

this tissue, which is synovium, and this tissue,

7:06

which is proteinaceous fluid, and this tissue,

7:08

which is synovium. And this is synovium.

7:12

So synovium against the background of proteous

7:15

fluid and synovium makes it

7:17

a little hard to discern,

7:19

a lot easier to discern on the sagittal water

7:23

weighted image about the T2 weighted image.

7:25

Let's have a look.

7:27

Let's go to the T2 weighted image.

7:29

And now it's really easy.

7:30

Now you can see the mixed heterogeneous character

7:35

of this mass, which is known as a cyclops lesion.

7:39

So hopefully you'll keep an eye out for the

7:41

cyclops lesion because it looks

7:44

a little bit like an eye,

7:46

and sometimes it even has a pupil in the middle of

7:48

it. This one a bit more amorphous and ill defined,

7:52

but rather large.

7:54

This is a definite cause of pain.

7:57

It restricts range of motion.

7:59

But despite all that,

8:01

let's look at the position of the tibia with the

8:04

patient on their back. Is the tibia translated?

8:08

So is there passive instability?

8:11

Right. We're not examining this patient.

8:14

So we're not examining this patient

8:15

for dynamic instability,

8:17

but we can assess for passive instability with

8:20

indirect signs like anterior displacement of the

8:23

tibia relative to the back of the femur.

8:26

I like these to line up about 5 mm

8:29

within each other vertically.

8:31

So if I take a line at the back

8:33

of the femoral cortex,

8:34

I want to be within 5 back of the tibia

8:38

on either side, and I certainly am.

8:41

So there is no passive anterior

8:45

tibial translation.

8:46

And I take the sagittal line or the lateral line,

8:51

the line that I just drew,

8:53

and I draw it where the tibia is furthest back.

8:55

So you can see they're almost congruent.

8:58

So this patient does not have passive

9:01

anterior tibial translation.

9:03

It's highly unlikely that they'll have dynamic

9:06

anterior tibial translation as well.

9:08

But there's going to be some micro instability and

9:12

friction going on in the notch because that's

9:15

how you get the cyclops lesion.

9:17

Let's look at a few other findings that

9:21

may catch your eye and define them.

9:24

One finding that may catch your eye is this,

9:26

this vertical signal in the

9:28

posteromedial meniscus.

9:30

How long will that vertical signal persist there?

9:34

Forever.

9:35

How do you know that's not a sign of a new recent

9:41

pivot shift injury? Well, here's one easy way.

9:45

The history. There's no new trauma.

9:49

Why not use what you've been given?

9:53

So it wouldn't make sense to have a pivot shift

9:56

injury without a history of trauma.

9:57

Second,

9:58

if this was a new vertical longitudinal

10:02

tear from another new pivot shift,

10:06

the ACl wouldn't look so good,

10:08

and you'd have some signal above and

10:11

below the area of abnormality.

10:14

No,

10:14

this is a tear with granulation

10:16

tissue that's healing. Now,

10:19

you might say what do you do about it?

10:21

Usually nothing.

10:23

Sometimes if it's very long,

10:25

it's got a lot of length.

10:26

A physician will stitch it,

10:28

but that has become less common now,

10:31

as we've learned that red, red zone, outer third,

10:35

vertical longitudinal tears that are not gapped

10:39

will heal on their own, scar on their own.

10:42

And you certainly can't go in here and take

10:44

out the outer third of the meniscus.

10:46

That's a disaster.

10:48

Let's look at the posterolateral meniscus.

10:50

Do we have something similar?

10:51

Not really,

10:52

but we do have a little bit of swelling at the

10:54

meniscocapsular junction from the original

10:57

pivot shift injury. It's kind of bland.

11:00

It's not very swollen.

11:02

There's no bone injury around it.

11:04

So there has not been a new pivot shift phenomena.

11:08

That being said,

11:10

there are biomechanics here consisting of micro

11:13

instability that are a this graft

11:16

that are producing cinnavitis,

11:18

that are resulting in a cyclops

11:20

lesion and an effusion.

11:22

So this patient has impingement syndrome

11:25

of their ACL graft with a large,

11:28

obvious cyclops lesion best depicted on the T2

11:31

weighted image. Let's do another one, shall we?