0:00

Okay, let's take a 63-year-old man

0:04

who's had prior surgery in the lumbar region.

0:06

I'm here with my colleague,

0:08

neurosurgeon and neuroimager,

0:10

Dr. Malcolm Schupeck.

0:11

And we've got a problem that is illustrated on a sagittal T2,

0:16

a sagittal non-contrast T1, and an axial T2.

0:20

I will also show the axial T1 in a minute.

0:23

And the patient has been instrumented.

0:26

So, we'll start off with some easy stuff.

0:29

Not going to talk about the degree of disc desiccation

0:32

and changes in disc space height.

0:34

We're going to focus primarily on the

0:35

postoperative scenario. And yes,

0:37

there is an abnormal area of disc displacement at the L4-5

0:42

level, but it's pretty concentric all the way around.

0:46

So let's stick with the main findings,

0:48

which are the area of instrumentation and this very large

0:53

collection. So let's begin with instrumentation.

0:55

Typically, and you're an expert at this,

0:58

I'm talking from the radiologic perspective,

1:01

you usually like to instrument and fuse

1:05

with bone or with some other material.

1:08

And then you have to consider all three columns of the

1:11

spine. Now, not in every case, as we both know,

1:15

there are some non-invasive procedures in people with

1:18

isolated fractures where you don't have to

1:20

stabilize all three columns of the spine.

1:22

But in general, when you're looking at the lumbar region,

1:25

you should at least consider the three columns.

1:28

Now, in this case,

1:29

the patient has had bipedicular

1:32

screw placement at two levels.

1:34

And it looks like they went in pretty much from the back,

1:39

which would be called a PLIF, which stands for what?

1:42

Posterior lumbar interbody fusion.

1:47

So that IF is going to be interbody,

1:50

meaning that's going to be an approach where something

1:53

is put in the disc space to bridge the disc space.

1:56

So what's put in there typically well,

1:58

usually what is put in is you're trying to get a bony

2:01

fusion. Okay. And when these things first started out,

2:05

that's exactly what they did is they did a laminectomy,

2:08

took the bone shards and just shoved it in there,

2:10

but it didn't work that well.

2:12

What is now done is there are instruments which would be a

2:17

cage or spacer that you can put bone in and

2:20

then other stuff to help bone growth,

2:22

like bone morphogenetic protein or something BMP.

2:26

So the cage is structural,

2:28

meaning the cage bears some weight until the

2:31

bone fuses through the cage is the idea.

2:34

Okay,

2:35

so you're trying to get some sort of interbody fusion.

2:37

So how you get the cage in there can vary.

2:39

So posterior in this case,

2:41

the laminectomy has been done and the cage has been put in

2:45

from anterior to posterior. You can come from the side,

2:48

which would be transverse lumbar interbody fusion,

2:51

where you take the facet off and try to kind of slide

2:55

it in, transforaminal. So that would go this way,

2:57

that way more. So that would be a TLIF.

2:59

A TLIF. Okay. This is a PLIF.

3:01

A PLIF. Now,

3:02

this is a unilateral PLIF in the sense that there's

3:05

one cage. You used to see both two cages.

3:07

People are going to one cage,

3:08

and the cage morphologies are getting more complex.

3:12

They're kind of curved and try to slide them

3:14

across and stuff like that.

3:15

Okay. Now,

3:16

you can also do something called an XLIF,

3:19

extreme Lateral that uses a flank approach,

3:23

and that's an interbody be up here,

3:26

but it doesn't go from back in.

3:28

It goes from out here.

3:29

They push the psoas back or go through the psoas.

3:32

So they go, put a giant tube right on the side,

3:35

drill a hole in the disc space,

3:36

and put a big cage so you can tell that one because

3:39

the cage is this big, rectangular thing.

3:42

Yeah.

3:43

And you could see that there's no way you could

3:45

get it in from the back.

3:46

Okay, just remember,

3:47

when you point to the screen, they can't see.

3:49

Right. Sorry. No worries.

3:51

That's what you're here for.

3:52

Yeah, that's what I'm here for.

3:53

So this would be yeah, extreme lateral approach.

3:58

Okay. Transpsoas approach.

4:01

And so that way you're not violating the

4:03

spinal canal at all. On the other hand,

4:07

a lot of these people who need that procedure

4:09

also need a posterior decompression.

4:11

So a very common thing to see is this XLIF approach,

4:15

big cage from this approach that Dr.

4:17

Pomeranz just showed you with that red arrow.

4:19

And that's this way, right?

4:21

And then augmented by posterior transpedicular screws

4:25

through a minimally invasive percutaneous approach.

4:28

Okay. So over the last seven to eight years,

4:31

this is a really common approach.

4:33

Eight or ten years ago, still very common.

4:36

That is posterior decompression,

4:38

doing everything from the back.

4:39

Transpedicular screws cage goes in from the back.

4:43

But in the last number of years,

4:45

you've seen these combined approaches

4:47

using the transpsoas approach,

4:49

cage in the front and then percutaneous screws in the

4:53

back. So you're going to see all combinations.

4:55

So just to be clear,

4:56

this patient did not have this XLIF, which is newer,

5:01

with pedicular screws in the back.

5:03

They had pedicular screws in the back.

5:05

They came in from the back with a PLIF.

5:08

And instead of doing two cages,

5:10

which has been standard in the past,

5:12

they just put in one cage.

5:14

And it's on the right side.

5:15

Now, you can see, though, right,

5:17

looking at the cage trajectory right there,

5:19

that in order to do this,

5:22

you'd have to retract the sac, right.

5:25

Because your cage is right in front of the sac.

5:27

And here's a sac over here.

5:29

Okay. Well, it's over here.

5:30

It's kind of not supposed to be.

5:31

I guess we'll get to that in a moment.

5:33

Right. But at any rate, it's in front of the sac.

5:36

So you retract the sac, whereas a TLIF,

5:38

one of the goals of that is you're coming out lateral

5:41

enough that you're not disturbing or retracting the sac.

5:44

Okay. So, TLIF, just to be clear for the audience,

5:47

a TLIF would be going this way.

5:50

Don't confuse that with what we were discussing before,

5:53

which is the XLIF, which is coming?

5:54

This one, right? Yeah. So the facet, if you have a TLIF,

5:58

they're going to go. Trans take that down.

6:01

So if you have an intact facet, okay,

6:05

that's one way to figure out whether it's a TLIF or not.

6:09

The angle coming in from lateral,

6:11

but also whether it is a trans facet procedure as opposed

6:14

to going right through the canal and retracting

6:17

the sac over. So once you see it there,

6:19

you have to kind of reconstruct in your

6:20

mind how it had to get there.

6:22

Because if you see something that there's no way you could

6:24

put in from behind, you know, an anterior procedure.

6:26

So let me ask you a couple of questions

6:27

and then in a separate section,

6:29

we're going to take on what's wrong with this case.

6:31

I want to ask you a few questions.

6:33

First of all, the cages typically metal or carbon cages,

6:38

but they also have plastic cages too, right?

6:41

Yeah, there's a number of different materials.

6:43

There's carbon fiber, there's some titanium cages.

6:46

There's something called PEEK, PEEK,

6:48

which is a kind of plastic material.

6:50

So there's a number of things that they can be made of and

6:53

there's generations, there's iterations going way back.

6:56

It used to be that there would be titanium kind of

6:58

mesh cages. So you'll see these in older things,

7:01

but they keep moving forward.

7:03

Then there's conical ones. Right.

7:06

So if you want to restore lordosis,

7:08

and that's something people want to do.

7:10

Sagittal balance is a big issue in

7:12

spine reconstructive surgery.

7:14

So now there's these shaped cages that you would put in

7:17

from the front to restore lordosis or do

7:19

something else that you want to do.

7:21

Well, no, it would be like this.

7:23

You would put in a conical cage like this.

7:28

Okay. And so that helps you restore lordosis,

7:32

a wedge shape. That's correct.

7:33

Okay. So it'd be more like this.

7:36

And that's because there's now a lot bigger

7:39

appreciation of the alignment,

7:40

the sagittal alignment of the spine and

7:42

how important it is in the long term.

7:44

So now all these options have been developed to allow you

7:47

to kind of taper and reconstruct and restore the kind

7:51

of alignment that you want.

7:53

My last question,

7:54

and you clarified this for me earlier,

7:56

but I think it's good to clarify for the audience.

7:59

The pedicle screw should be aligned with the course

8:02

of the pedicle, with the trajectory of the pedicle.

8:05

And there's a little bit of controversy in the radiologic

8:09

versus the neurosurgical literature.

8:10

The radiologic literature says you shouldn't

8:13

really have any cortical perforation.

8:16

And we discussed before a little bit of cortical

8:19

perforation is probably okay as long as you're not

8:23

touching any special structures like the

8:25

aorta or the iliacs or whatever.

8:27

Yeah.

8:28

Meaning that if I read one of these things and the screw

8:32

is sticking out here anteriorly and it's through,

8:37

I don't say, hey, your screw is too long.

8:40

Okay?

8:41

I say there is bicortical purchase of that screw because

8:45

there are surgeons who try to get bicortical purchase.

8:48

Okay.

8:49

Now the other thing is these are transpedicular screws.

8:52

But there is also a kind of newer root trajectory

8:55

that goes from inside out.

8:57

Like this.

8:58

Okay. And you say, well.

8:59

What's happening here? Cortical bone screws.

9:02

Yeah. Okay.

9:03

So you're going to start seeing those not as commonly,

9:06

there's a lot more pedicle screws out there,

9:08

but a lot of sophisticated spine surgeries are now

9:12

adopting that approach of these laterally directed screws.

9:16

So before you start commenting on

9:20

trajectory, is this good, is this bad?

9:23

You kind of have to start to understand these operations

9:25

a little bit and what the goal is.

9:27

Because remember what we're trying to tell people.

9:30

They're scanning somebody because they had an

9:32

operation and something's not going right.

9:34

So we're trying to help them understand what's going on.

9:37

And to do that,

9:38

you have to understand what the intent was.

9:40

One of the questions that they want is,

9:42

was the intent of the operation achieved?

9:44

Sure. Okay. Other thing, could it be the wrong operation?

9:47

Was there's all kinds of permutations?

9:50

But that's one is,

9:51

was the technical goals of the operation achieved?

9:53

But so you have to know what operation was

9:55

being attempted. So just to summarize,

9:59

we've talked about the PLIF and the newer variations

10:02

of the PLIF, the TLIF, the XLIF.

10:05

There's also an ALIF where they come in from the front.

10:07

They actually have to do a laparotomy, right?

10:10

Yeah.

10:10

Although those are done usually retroperitoneal approach

10:13

of some sort, and endoscopically a lot these days.

10:16

Okay. So they're anterior approaches.

10:19

You can do big, open anterior approaches,

10:21

but they've gotten more and more minimally invasive.

10:23

The big thing you're going to see in surgery these days,

10:26

I just got back from the AS meeting,

10:28

is so-called MIS spine, minimally invasive spine.

10:32

So you're going to see all of these sort of

10:34

approaches working through endoscopes,

10:36

working through small incisions instead of big,

10:39

open incisions,

10:40

and getting instrumentation in their various ways without

10:43

the kind of soft tissue injuries we used to see in these

10:45

big midline incisions. Great. Let's stop there.

10:48

And then in part two,

10:49

we're going to talk about what's wrong with this patient.