0:00

So for the transverse type fractures,

0:02

this basically breaks the acetabulum into

0:05

top and bottom halves.

0:06

The main fracture plane goes from anterior

0:09

to posterior across the acetabulum.

0:12

So on CT there'll be a sagittal fracture plane identified.

0:15

And the types of fractures that go into this category

0:19

include that T-shaped fracture, transverse fracture

0:23

with the posterior wall, a pure transverse fracture

0:27

or an anterior column fracture

0:29

with the posterior hemi transverse.

0:32

So here's an example of an acetabular fracture

0:34

where we have the anterior column

0:36

with a posterior hemi transverse.

0:39

We can see a fracture here going

0:42

through that anterior column.

0:44

And then on our iliac wing juda projection,

0:48

we can also see a lucency that has a more

0:51

of a transverse component going through the posterior aspect

0:54

of the acetabulum.

0:56

So this is an anterior column

0:58

with posterior hemi transverse.

1:01

Now the column fractures divide

1:03

or break the acetabular into front and back portions.

1:06

The main fracture plane is now in

1:08

that cranial-caudal direction.

1:10

So on CT imaging there's gonna be a coronal fracture

1:13

plane that's identified.

1:15

Now the types of fractures

1:16

that would go in the column category

1:19

include a pure posterior column or a pure anterior column.

1:24

You can have a combination where you have both columns,

1:27

again, the posterior column through the lower portion

1:30

and an anterior column through the upper portion,

1:33

a posterior column with a posterior wall

1:37

or an anterior column

1:38

with a posterior hemi transverse component.

1:42

So here's a CT exam where we see that the main

1:46

fracture plane is in the coronal orientation.

1:50

And so this is an example of an anterior column fracture.

1:53

There's our fracture line

1:56

and we can see that it's in that coronal plane

1:59

based on both the axial and the multiplanar reconstruction.

2:03

Now with acetabular wall fractures, they involve portions

2:08

that do not disrupt the load-bearing columns.

2:11

So there, that's why their wall,

2:13

rather than column fractures, they can be associated

2:17

with hip dislocations.

2:18

And when that occurs, there's a higher risk of osteonecrosis

2:21

of the femoral head because of that tenuous blood supply

2:24

that we discussed previously.

2:27

This leads to hip joint instability

2:30

rather than pure incongruity.

2:33

And on the CT there'll be a more complex

2:35

or oblique fracture plane that's encountered.

2:38

So the types of fractures that go in the wall category

2:42

include the pure posterior wall.

2:45

You can have a posterior wall

2:46

that extends into a posterior column.

2:49

Again, because it's involving now the load-bearing portion,

2:53

so it's beyond the wall,

2:54

but into the column, you can have a posterior wall that has

2:58

A transverse component or an anterior wall fracture.

3:04

So while we're focusing on radiography, here are some

3:06

of the CT appearances.

3:09

So here's a diagram of the normal acetabulum

3:12

wall fractures would involve,

3:14

in this case the posterior wall through a portion

3:17

of the acetabulum Transverse fractures

3:21

have this interop posterior

3:23

or sagittal orientation column fractures will have this

3:28

medial lateral or coronal orientation.

3:31

And those are the main fracture planes that help you

3:33

to putting them into the different categories.

3:36

So while there are 10 types, there are five

3:39

that are more common that are counting for approximately 90%

3:42

of all the acetabular fractures.

3:45

So those consist of the posterior acetabular wall fracture,

3:49

pure transverse fracture, a transverse fracture

3:52

with posterior acetabular wall involvement.

3:56

So combination of the wall

3:57

and the transverse component, a

4:00

complete both column fracture or a T-shaped fracture.

4:05

So posterior acetabular wall fractures

4:07

are really the most common.

4:08

They're about a quarter of all the acetabular fractures.

4:11

That fracture involves that posterior acetabular rim.

4:15

A portion of the retro acetabular surface,

4:19

a variable segment of the articular cartilage,

4:23

and they're often associated with posterior dislocations.

4:26

So here's a diagram showing, uh, posterior wall fracture

4:30

and again, disruption through the posterior wall,

4:33

but not necessarily through the load-bearing column.

4:36

And you can see this is related to having, uh,

4:39

hip dislocation or subluxation event.

4:42

And here on CT we see that bony fragment

4:46

of the posterior wall that's minimally displaced.

4:50

Transverse fractures are the second most common type.

4:53

So this fracture involves both the anterior

4:55

and posterior columns and frequently the ischial spine.

4:59

They're usually associated with central dislocation

5:03

of the femoral head and seen here in the diagram

5:06

on the cross-sectional image that can be identified by their

5:10

sagittal or interop posterior orientation.

5:14

Here we see it on CT with that characteristic

5:18

sagittal orientation representing a transverse fracture.

5:23

So you can have a combination

5:24

of the transverse acetabular fracture

5:26

and the posterior wall fracture.

5:28

So this is one of the more common associated fractures

5:32

and can account for approximately one fifth

5:34

of all acetabular fractures in this type of fracture.

5:38

And in nearly all cases, the femoral head dislocates

5:42

more commonly posteriorly or less commonly anteriorly.

5:47

So here on CT we see a more complex fracture pattern

5:51

where we have a transverse component with

5:55

that sly oriented

5:57

Or anterior posterior oriented component

5:59

of the fracture line.

6:01

And then also a posterior wall component

6:04

where we have displacement

6:06

of this posterior bony wall fragment.

6:09

Now with both column fractures, we have fractures

6:12

that extend through both the anterior and posterior columns.

6:15

And when this occurs, it creates a floating acetabulum.

6:19

So floating acetabulum is a separation

6:21

of the entire surface from the pelvis.

6:24

Remember the hip is typically on a fixed base.

6:27

And now with this both column fracture,

6:30

we have a separation from the base.

6:32

This can have a characteristic radiographic appearance

6:35

generating the spur sign.

6:37

So the spur sign is related to medial displacement

6:41

of the two columns

6:43

with the buttress from the sacroiliac joint

6:45

remaining in normal position.

6:47

And it's being seen as this shard

6:49

or projection of bone posterior

6:51

to the displaced column fragments.

6:55

So you've seen this sign in one

6:56

of our previous case examples

6:58

and this is how that finding is generated.

7:01

So we have our plane of section or our imaging projection,

7:06

and because of the offset of the columns,

7:11

it then generates this bony projection

7:13

known as the spur sign.

7:15

This is typically identified on that opterator

7:18

oblique projection.

7:20

So best identified on that 45 degree Judea view

7:24

of the opterator, oblique of the ipsilateral

7:27

or affected side on ct.

7:31

Of course, it will help you characterize a fracture

7:34

with the cross-sectional imaging showing that multiplanar

7:38

configuration and then involving both anterior

7:41

and posterior columns.

7:43

So here's an example on axial CT images

7:45

of both column fracture.

7:48

So we have two fracture fragments.

7:51

The white arrow points to the posterior component,

7:53

the red arrow points to the anterior component

7:56

or anterior column fragment.

7:59

And so we see on the white arrow

8:01

that those pieces are contiguous

8:04

and involving the posterior aspect of the pelvis.

8:08

And the red arrow is the anterior aspect of the pelvis.

8:13

Now if we look at our image down here, we see

8:16

with the green circle that

8:18

that posterior column fracture has this uh, bony spur

8:22

or bony fragment that's gonna project lateral

8:26

to the remainder of the pelvis.

8:28

And that's what generates our spur sign.

8:31

So with the T-shaped fractures,

8:33

we have a transverse fracture of the acetabulum

8:36

with a perpendicular oriented vertical component.

8:39

This can resemble a both column fracture.

8:41

However, the top half of the fracture remains connected

8:44

to the axial skeleton,

8:46

basically representing an intact strut

8:48

of bone from the sacroiliac joint to the articular surface

8:52

of the acetabular dome. But

8:54

Can look quite complex on our cross-sectional imaging

8:58

as we see in the figure here.

9:00

And so with that T-shaped fracture, we're gonna have

9:03

a sagittal or anter posterior component.

9:06

And then we're also going to have a transverse

9:10

or medial lateral component to the fracture plane.

9:14

So this can be a complex area to approach.

9:18

One way to approach it is to use a checklist approach.

9:21

This checklist is maybe based off of several questions

9:25

on some, uh, classification observations.

9:28

So looking at a pelvic trauma case, particularly

9:33

with respect to identifying acetabular injuries, we can ask

9:37

is the IOP pectineal line disrupted?

9:40

Is the ileal issue line disrupted?

9:42

Is there an oblique fracture

9:44

of the anterior iliac wing extending above the acetabular?

9:48

Is an operator ring fracture? Present?

9:51

Is a posterior wall fracture present?

9:54

Does the fracture divide the acetabulum into top

9:57

and bottom halves or front and back halves?

10:00

Can an intact strut of bone be followed from the SI joint

10:04

to the acetabular articular surface

10:06

or is there the spur sign?

10:09

And then what is the main plane on the CT exam?

10:13

So how those questions are answered can be put into this

10:16

table or matrix here to help you identify

10:20

what type of fracture it is.

10:22

And so this is a useful resource not to memorize,

10:25

but to keep available when you encounter a pelvic fracture

10:29

if you'd like to be accurate in categorizing it.