0:00

Here is our radiographic evaluation of the AC joint

0:05

and as mentioned on the frontal projection, we look

0:08

for the relationship of the under surface of the chromium

0:12

with the clavicle to maintain that normal alignment.

0:15

What we don't see directly

0:17

but we infer by widening, is the integrity

0:21

of the acro clavicular joint

0:23

and the cortical clavicular ligaments.

0:26

So these are our normal relationships of the AC joint

0:30

and the clavicle here.

0:32

In a person with an acromioclavicular joint dislocation,

0:36

we see loss of alignment of the undersurface of the clavicle

0:40

with the acromium representing capsular disruption

0:43

of the AC joint

0:45

and widening of

0:46

that corco clavicular interval representing

0:48

ligamentous disruption.

0:51

AC joint injuries are typically characterized

0:54

by the Rockwood classification shown in the drawings here.

0:58

A grade one is a capsular sprain where the AC joint

1:03

may be slightly offset or not even noticeably malaligned.

1:08

A grade two injury represents AC joint capsular disruption

1:12

where you typically have some degree of widening of that

1:16

AC joint Interval grade three

1:19

and above now involve injury

1:21

to the corco clavicular ligaments.

1:23

So in a grade three type injury, there's disruption

1:27

of the AC joint capsule and the corco clavicular ligaments.

1:31

So in addition to AC joint widening,

1:34

there is also elevation of the clavicle.

1:36

Grade four through six

1:38

have some other complicated features to them.

1:41

In a grade four, you then have some posterior displacement

1:45

grade five maybe into the muscle,

1:48

and grade six is below the cricoid.

1:52

So here's an example of a type two AC joint injury.

1:56

AP radiograph of the shoulder shows a widen AC joint.

2:00

There is no elevation of the clavicle

2:02

and the corco canicular distance is normal.

2:05

There's some mild overlying soft tissue swelling.

2:08

Here we have a grade three AC joint injury

2:11

where our AP bilateral zenga type view

2:15

with the person holding weights shows a vertical widening

2:19

of the left AC joint with clavicular elevation related

2:23

to the acromion and also asymmetric widening

2:26

of the CC interval.

2:29

In this person here who also had a higher grade AC joint

2:33

injury, the AP radiograph

2:35

shows a dislocation of the AC joint.

2:39

But if you look more carefully where the arrows are,

2:41

there's some subtle LOEs of gas within the joint

2:44

and adjacent to the clavicle.

2:46

Here in the type four AC joint injury,

2:49

there is a frontal radiograph

2:51

of both clavicles which show swelling over the right AC

2:53

joint, which is minimally wider than the left,

2:57

but still within the normal range

2:59

And a relative normal coracoclavicular distance

3:03

here in a type five AC joint injury.

3:06

The AP upright bilateral radiograph

3:09

with the patient holding weights shows marked widening of

3:12

that left CC interval

3:14

and vertical offset at the AC joint

3:17

grade five injury results in greater separation

3:19

of the CC distance then does a grade three injury

3:23

with the separation typically being greater than double the

3:26

width of the normal size owing to an unopposed action

3:29

of the sternal colido mastoid Following a delta

3:32

trapezial tearing.

3:34

This high grade injury involves superior displacing

3:36

of the clavicle and inferior depression of the scapula.

3:41

So AC joint separations can get even more complex.

3:44

So in this example here we have a coracoid fracture

3:48

in the setting of a grade three equivalent

3:50

type AC separation.

3:52

So is elevation of the clavicle relative

3:55

to the acromion shown with the arrow.

3:58

And there is a fractured cricoid process that's identified

4:02

by the asterisk, which is elevated from the base

4:05

of the cricoid, but maintains its

4:08

relative distance to the clavicle.

4:10

So in addition to routine type AC separations

4:14

where we have capsule

4:15

and ligamentous injury, we may also have concomitant

4:19

distal clavicle fractures,

4:21

which then complicate the situation.

4:24

So distal clavicle fractures

4:26

typically also involve some type of AC joint separation.

4:31

And in this regard, these are characterized

4:34

by the near classification, which is shown here.

4:38

So in type one we have a simple distal clavicle fracture

4:42

without disruption of the ligaments.

4:44

Type two, you can have a fracture that's medial

4:48

to the corco clavicular fixation,

4:50

which does not involve an AC joint separation per se.

4:54

Or you can have partial involvement of a portion

4:58

of the corco clavicular ligaments.

5:00

Or you can have a very distal clavicle fracture,

5:02

which involves the articulation.

5:05

Or in a type four, which is a pediatric injury,

5:08

you can have periosteal sleeve evulsion where the epiphysis

5:12

of the distal clavicle maintains its

5:15

relationship with the acromion.

5:16

But now the clavicle is stripped outta the periosteum

5:20

and the coco follicular ligaments may be maintained.

5:23

Or you can have fracture fragment of distal clavicle

5:26

with an avulsion of the attachment

5:29

to the corco follicular ligaments as in a type five.

5:34

So here's an example of

5:36

a near type five distal clavicle fracture here.

5:39

The AP radiograph shows a communative fracture

5:42

of the inferior clavicle.

5:44

You can see the free floating bone fragment

5:47

labeled in the asterisk arising from that inferior clavicle,

5:51

which includes the attachment

5:52

to the coracoclavicular ligaments.