0:01

Now this brings us to the concept, the important concept

0:05

of the glenoid track.

0:07

And I think this is somewhat of a, uh, confusing, confusing,

0:12

uh, uh, topic

0:14

because the glenoid track is actually painted on the humerus

0:18

and what occurs as you go, uh,

0:21

into maximum external rotation with increasing degrees

0:25

of abduction, the glenoid paints this particular region

0:29

of contact zero 30 degrees

0:32

and 60 degrees of abduction.

0:35

This is the glenoid tract painted on the proximal humerus.

0:40

And if you look at that glenoid track, there is a width.

0:44

The width, the medial margin is the, uh,

0:47

or it's a strong here from the medial margin

0:51

of the rotator cuff tendon footprint in a

0:56

medial direction.

0:57

And there is a way of calculating what it should be.

1:02

And that relates to measuring the diameter

1:05

of the glenoid face.

1:07

Number of articles have suggested that the width

1:10

of the glenoid tract, okay, between the green arrows is

1:16

about 83 or 84% plus

1:19

or minus 12% of the maximum width

1:23

of the glenoid cavity.

1:25

And this becomes important, okay?

1:28

Because if a hill sax lesion does not extend

1:30

beyond the medial margin of that glenoid tract,

1:35

joint stability is generally guaranteed.

1:38

Now, the problem with this is the variability

1:42

and some orthopedic surgeons prefer not to go ahead

1:45

and calculate the glenoid tract

1:47

and whether you have measurements

1:49

that suggest in fact the sax lesion is to large,

1:54

but rather under anesthesia at the time of surgery

1:58

to go ahead and see if there is, there is re-engagement

2:02

of the humeral head.

2:05

What it can occur in some people is that

2:08

as you go from neutral to external rotation,

2:11

you will re-engage that hills sax lesion on the anter aspect

2:17

of the glenoid, particularly if it is large.

2:19

And then as you internally rotate

2:22

after that, the humeral head will ate.

2:27

This has led to a concept that is called uh, unipolar

2:31

and bipolar lesions and on track and offtrack lesions.

2:36

Unipolar simply means you have either a bone bank

2:39

art or a hill sax.

2:40

Bipolar means you have a bone bank art

2:44

and a hill sax lesion.

2:47

On track means there is in fact measurements

2:50

that would suggest that there is adequate phone support

2:55

and reengagement is less likely.

2:57

Okay? Off track

2:59

Would suggest the opposite.

3:01

So if the hills sax lesion shown here is less than

3:05

83% of the maximum measurement of the glenoid face,

3:09

this would be an OnTrack hill sax lesion

3:13

unipolar in this particular drug.

3:16

And if in fact the opposite is true here

3:19

with a bipolar lesion

3:21

where the hills sax lesion is greater than

3:24

83% of the entire width

3:28

of the glenoid and you have

3:30

to do another calculation related to in fact

3:34

how much bone is lost, then indeed

3:37

you will have an off track I sax lesion.

3:41

Now, do we do this in every single case where we're studying

3:44

uh, cases of instability?

3:47

No, but we have certain orthopedic surgeons who do like us

3:50

to determine unipolar bipolar

3:53

and whether we're dealing with OnTrack or offtrack lesions.

3:57

Just to give you an idea of what it looks like,

4:00

here is an OnTrack lesion at the time of arthroscopy.

4:05

You can see that hill sax is not re-engaging

4:08

the anterior glenoid margin, and here is an offtrack lesion.

4:12

Look at the re-engagement right there

4:14

of the hills sac lesion with the glenoid margin.

4:19

Now there are treatments, uh, strategies for

4:22

engaging hills sac lesion.

4:24

One of the strategies is you can fill the bone defect

4:29

and listed what you can do to do that.

4:33

One of 'em, the REM massage procedure.

4:35

Here, you can see what they might do using the infraspinatus

4:39

tendon with a screw covering portions of

4:43

that hill sax lesion.

4:45

The other way

4:46

of treating these is limited external rotation.

4:49

A rotational humeral osteotomy magnus,

4:52

and stack putty plat procedures can do that

4:55

when we're dealing with an engaging bone bank art lesion.

4:59

The classic surgery is the laer procedure, where indeed

5:04

what you do is you transfer the coracoid process

5:07

with its conjoin tendon sling that is the biceps

5:11

and the cortical brachialis,

5:13

and you transfer to the anteroinferior aspect

5:16

of the glenoid, and that provides stability

5:19

through these four particular effects,

5:24

the bone effect because you have more bone down there,

5:26

the muscle effect

5:29

because there's increased tension on the subscapularis

5:32

tendon, the conjoint tendon shown here,

5:35

which will also produce a soft tissue restraint

5:39

and you repair the capsular laxity.

5:42

All four are important effects that increase stability

5:46

following the latter herge.