0:00

Let's turn our attention now to the Bone

0:04

Bank heart lesion.

0:07

This is associated with certain types

0:09

of anterior Glen Al joint dislocation.

0:11

Of the ones we've described, the ones that come to mind

0:15

are the subcoracoid and sub glenoid dislocations.

0:19

I think that the, this lesion, this bone bank card,

0:23

is probably equally frequent in both

0:26

of those types of dislocation.

0:28

Although the position may vary.

0:31

It may be lower when the dislocation was sub glenoid. Okay.

0:36

There's an increase likelihood of recurrent dislocation

0:41

with a greater size of this particular bone defect.

0:46

So the orthopedic surgeon treating patients

0:49

who have anterior macro instability

0:51

and trying to decide on the risk of reengagement

0:56

and recurrent dislocations are interested in the location

1:01

and size of the hills sacs

1:04

and bone bang heart lesion.

1:08

Now let's see how the bone bang heart lesion is classified.

1:11

You know, when I was a resident radiology, I thought it had

1:15

to be an avulsion fracture.

1:17

It does not. It can be a compression fracture.

1:21

The evulsion fracture shown here in this particular picture

1:25

taken from the literature is generally observed at the time

1:30

of dislocation.

1:31

Often the initial dislocation,

1:34

and if it is an avulsion fracture,

1:36

there is a lesser frequency

1:38

of hill sax lesion over time.

1:42

What may occur is that fracture fragment may resorb

1:45

and you're left with anter glenoid deficiency,

1:49

as you can see here, because the fragment is gone.

1:53

The second type of fracture is a compression fracture shown

1:58

in this illustration.

2:00

There's no fragment here.

2:02

This generally becomes more evident with a passage

2:05

of time owing to glenoid bone erosion

2:08

and often recurrent dislocations.

2:11

And it is often accompanied by a hill sax lesion, as I said,

2:17

multiple dislocations.

2:19

Now whether you're dealing with an avulsion fracture, one

2:22

with resorption or not,

2:24

or a compression fracture, it changes the shape

2:28

of the glenoid face.

2:30

As we mentioned. Typically it is a pear shape.

2:34

I like the avocado shape, but pear shape.

2:37

And when you have deficiency of the anterior glenoid margin,

2:41

it becomes an inverted pear where the lower half is not

2:46

as wide as the upper half,

2:48

and that can occur with a fragment

2:50

or with a compression fracture.

2:55

So how do you decide how much of the anterior

2:58

Glenoid bone is missing?

3:00

Well, it's based on the concept that I introduced, uh,

3:04

yesterday, and we'll will mention again today

3:07

that if you look at the shape of the glenoid,

3:11

the lower two thirds is similar to a circle.

3:15

Now, anyone who tells you it's identical

3:18

to a circle is incorrect.

3:20

It's been shown that it's like a circle

3:22

but not a perfect circle.

3:25

And in therefore, you can identify in the middle

3:28

of the circle an area known as this bare spot.

3:33

And that bare spot is often associated with cartilage

3:37

that is thinner and sometimes an area of bone proliferation.

3:42

And you can identify it by the way, sitting here, the fact

3:46

that it is located right there in the middle

3:48

of the near circle that we see in the lower two thirds,

3:52

usually we don't confuse it with osteochondritis

3:56

or an osteochondral injury.

3:58

I'll talk more about that in the second uh, lecture,

4:02

but there is some controversy about it.

4:04

But this is the concept that is the basis

4:07

for the circle method.

4:09

So using the circle method

4:11

and suggesting it's in the center of a circle,

4:15

occupying the lower two thirds of the glenoid,

4:18

the radius should be the same as you draw it from

4:22

that particular bare spot anteriorly and posteriorly.

4:26

And when you have a bone bank heart leading to

4:30

either a fragment

4:31

or a compression, you can see how much bone loss is

4:35

and create a ratio of that particular bone loss

4:40

to the diameter of the glenoid face.

4:44

And there is evidence to suggest that the critical amount

4:47

of glenoid bone loss usually 20 to 25%.

4:52

But if you go into the literature, there is literature

4:56

that would suggest if it's even greater than 14%,

5:01

it often is associated with unacceptable clinical outcomes.

5:05

And although not always related to

5:08

recurrent instability, here's an example.

5:11

The bottom right showing you the measurements

5:14

that could be done.

5:15

As I say that, uh, Dr.

5:17

Pomerance will go into a little more detail about

5:20

how exactly you can do it.

5:22

And I think he's gonna tell you how he can do it quickly.