0:00

So as far as complications,

0:01

we've talked about some of these already.

0:04

We talked about graft impingement,

0:05

and we'll show you more examples of that.

0:07

Certainly we wanna look for graft disruption, uh,

0:10

in patients who have re injuries

0:11

of their knee following reconstruction, our th fibrosis,

0:15

whether it's global or, uh, focal.

0:18

Um, any hardware failures, hardware migration,

0:21

and I'm not gonna talk about double bundle reconstructions,

0:24

um, as that's kind of a whole another topic in of itself.

0:28

But, uh, be cognizant that, uh, you may encounter double,

0:31

uh, bundle reconstructions

0:32

and the complications overall are similar.

0:37

So with regards to acute graft tears similar

0:41

to the native ACL,

0:43

we can subdivide things into primary MRI signs

0:46

that means problems intrinsic

0:48

to the anterior cruciate ligament or secondary signs.

0:52

Now you have to be careful with the secondary

0:53

signs these have to redo.

0:55

These have to do with malalignment of the knee.

0:57

So anterior tibial translation,

1:00

while they're good in the native knee

1:02

and the native injured ACL, they're not

1:05

as good in the reconstructed knee.

1:07

And I'll show you why. But as far as primary signs go,

1:10

similar to the native ACL, we wanna look for signal

1:13

or morphologic changes, changes in orientation, areas

1:18

of fiber discontinuity, and changes in graft thickness.

1:22

Unfortunately, a lot

1:24

of these findings can be seen in both full

1:26

and partial thickness tears.

1:29

And depending on the age of the graft, as I alluded earlier,

1:31

if you image earlier, you might see some areas

1:34

of increased signal with intact grafts.

1:37

So here's an example of a patient with an acute graft tear.

1:40

We can see focal high signal on our fluid sensitive sequence

1:44

through the mid portion of the graft,

1:46

and this patient had clinical laxity on exam.

1:51

Here's another, uh, example of a complete graft tear,

1:54

which is more chronic.

1:56

Now in this stage, and we can say it's chronic

1:57

because we no longer see any visible graft fibers,

2:01

so similar to the native anterior cru ligament,

2:04

it can either undergo scarring

2:06

or completely resorb over time.

2:09

So this is a complete tear with graft resorption.

2:13

Here's why. Secondary signs not as helpful in the

2:17

reconstructed ligament.

2:19

So this is a paper, um, roughly 10 years ago, uh,

2:22

looking at the secondary signs.

2:24

And they found that if you had slid anterior translation,

2:27

the tibia relative the femur, this had a kind of a low

2:31

positive predictive value for predicting patients

2:36

to have laxity on clinical exam.

2:39

So if you see this finding, it won't,

2:41

it doesn't really have a lot of meaning.

2:43

And why is that? It's probably has to do

2:45

with anterior cruciate ligament reconstructions.

2:48

While we strive to attain perfect anatomic

2:53

reconstructions, sometimes these, uh,

2:55

ligaments are not quite placed in a perfect anatomic

2:58

reconstruction, particularly for single, um,

3:01

bundle reconstructions as opposed to, uh,

3:04

double bundle reconstructions where they're trying

3:06

to create both the antal

3:08

and posterolateral bundles in a more anatomic fashion.

3:13

Conversely, if you see normal alignment,

3:15

so say this tibia was lined up perfectly

3:18

with the posterior aspect of the lateral femoral condyle,

3:22

then this had a high native predictive value, meaning

3:25

that you were unlikely

3:27

to have any translational laxity on exam.

3:33

We've talked about roof impingement,

3:35

particularly in the setting of tibial tunnels

3:37

that are too far anterior.

3:40

And sometimes you'll read in the operative notes

3:42

that the arthroscopy will pull, will perform a notch plasty,

3:46

meaning they'll debride a little bit of bone to make room

3:49

for the graft, but obviously they won't want to over debride

3:52

and create a, uh, um, a, a situation

3:56

where you have knee laxity.

3:58

So again, just look for any kinds of posterior bowing.

4:02

If you see attritional changes

4:03

or thinning of the reconstructed ligament,

4:07

then you are likely dealing with roof impingement.

4:10

Also, these patients may present with, um, loss

4:13

of terminal knee extension.

4:15

Here's just another example of a patient

4:17

with roof impingement.

4:19

Their tibial tunnels a little bit anterior location,

4:22

but even even more importantly, you can notice

4:24

that their femoral tunnels way too anterior was probably

4:28

placed in front of that lateral intercondylar ridge

4:31

or residence ridge.

4:35

So similar to cystic degeneration

4:37

of the native anterior cruciate ligament.

4:39

This can also happen in the reconstructed ligament.

4:42

This can in, uh, affect the intra, um, the joint portion

4:47

of the reconstructed ligament,

4:49

but can also affect the bone tunnels as well.

4:52

So here you can see almost that celery stock appearance of

4:56

that, uh, reconstructive ligament heading into bone

4:59

and resulting in tunnel widening.

5:02

And in of itself, if the patient has a clinical stable exam,

5:06

probably not that important,

5:08

but further down the road, should they tear their ligament

5:11

and require an additional surgery

5:13

or reconstruction, this can result in, um, problems.

5:17

So tunnel cysts, when the largest more than 14 millimeters

5:22

and the patients require a redo surgery, this is, uh,

5:25

where the patients may require a two stage revision.

5:28

So here's an example of a patient

5:30

with enlarging tunnel cyst.

5:32

This is, uh, by eyeball more than 14 millimeters.

5:36

And so here's another example of a patient

5:38

with a large tunnel cyst who had

5:40

to undergo grafting of the tunnel.

5:42

Wait several weeks for the bone graft to mature

5:45

before undergoing a second ACL reconstruction.

5:50

Here's an example of other tunnel complications.

5:53

This was a, uh, former, uh, professional

5:56

Football player of the Chargers organization underwent a

5:59

bone patella tendon bone autograph.

6:02

You can see the changes of the inferior pole, the patella,

6:05

and you can see that the interference screw should be in

6:08

line with the femoral tunnel

6:10

and the bone plug that's also supposed to be in line

6:13

with this, uh, interference screw has dropped into the joint

6:17

and, uh, was actually astutely picked up on the MRI

6:21

and then subsequently confirmed on CT.

6:25

STR fractures are relatively uncommon.

6:27

They tend to occur more on the femoral side.

6:30

Uh, they tend to occur more, um, with larger tunnels

6:33

and that tends to make sense.

6:35

The lower bone you take away, the more likely you're going

6:38

to result in a stress riser.

6:41

So here's an example of a pediatric patient

6:44

who underwent an ACL reconstruction

6:46

with a distal femur stress fracture.

6:48

Whether this is truly a causal relationship to the, um,

6:51

anterior cruciate ligament reconstruction,

6:53

I can't really prove or whether this is just a simple matter

6:57

of fact stress fracturing a patient who, uh,

6:59

with overactivity, certainly we wanna look for,

7:04

uh, hardware complications including hardware migration.

7:08

Here's an example, uh,

7:09

from the literature showing a uh, button.

7:12

Now remember, these are cortical buttons that they're placed

7:14

through the femoral tunnel and flipped,

7:16

and that's how they engage on the, uh,

7:19

of the supracondylar ridge, of the distal femur.

7:22

Much like when you button a shirt

7:23

that keeps it secure in place.

7:27

Here's, uh, one in the literature

7:28

that was placed in the soft tissues,

7:30

and these can be, uh, pretty dramatic

7:33

because as you can imagine, the tension

7:35

of the graph can result in, um, tension on the button and

7:39

therefore tissue necrosis.

7:43

One thing I didn't talk about is a different type

7:45

of graph fixation that you may encounter are cross pins.

7:49

These are another form of dispensary fixations,

7:52

and these are placed along the, um, distal femur.

7:55

And ideally these cross pins should be

7:57

placed entirely within bone.

7:59

But on occasion, these are an inadvertently placed within

8:02

the soft tissue soft tissues outside the femur.

8:05

And here's a couple of cases of broken cross pins

8:08

that were placed outside the femur.

8:12

Here's a case, uh, from our, um, case files

8:15

where a cross pin was placed outside the femur

8:17

and have actually fractured

8:19

and migrated into the gastroc anus muscles.

8:22

You can see here actually dissecting through, uh,

8:25

the intramuscular vein of the gastroc neis muscle back here.

8:30

Certainly, uh, when we have fixation screws,

8:33

these interference screws can migrate as well.

8:36

This one, uh, I can't tell, we don't have pre, um,

8:39

prior imaging demonstrating whether this has extruded

8:43

superiorly or this is how it was natively placed.

8:45

But you can see that there's local localized arthrofibrosis

8:48

raising the possibility of a cyclops lesion

8:52

as we look in the second case.

8:54

Here's another example of screw protrusion at

8:56

the inferior aspect of the tunnel.

8:58

And this has to be correlated with clinical findings.

9:01

Whether this is a symptomatic finding

9:03

or not, here's a more dramatic case of a screw

9:06

that extruded into the subcutaneous adipose tissues.

9:10

So this patient actually had it

9:12

to undergo screw removal given that it was, uh, completely

9:16

underneath the skin

9:17

and mobile I alluded to.

9:22

Um, when placing the femoral tunnel too far posterior,

9:25

you can, uh, encounter this, uh, entity

9:28

of posterior wall blowout,

9:30

so the posterior cortical margin is violated.

9:32

And you can see that the femoral button now is floating in

9:36

space, uh, detached, uh, from the graft.

9:40

And here it is on ct, not engage

9:42

with the lateral cortical margin of the distal femur.

9:45

I.