0:01

A 75 year old with left thumb pain and difficulty after an injury.

0:07

So for my thumb, uh, when I read a thumb, MRI,

0:11

I like to have again, typically my coronals on top, axials on the bottom,

0:17

and along with the sagittal here and, uh,

0:20

going to write to the salient finding. Okay, we see here,

0:26

and I'll link these for us. We see here's, uh,

0:30

particularly on the conned in view or the, uh,

0:35

zoomed in view of the coronal proton density, uh, fat suppressed sequence.

0:39

We see that the, uh, ulnar collateral ligament at its distal attachment,

0:44

okay.

0:44

And the ulnar collateral ligament at the MCP can be divided into two

0:49

components. That is the accessory and the proper okay.

0:53

Ulnar collateral ligament. But, uh, in, at least under, with,

0:56

under my experience, I have a very difficult time of parsing those out.

1:02

So I'll, I will just say a ligament is complex and what we see here, okay,

1:07

is that that ligament ulnar collateral ligament has failed distally and is

1:12

actually torn and approximately retracted,

1:15

such that it's distal fibers are oriented and face,

1:20

okay, uh, proximal narly. Okay.

1:25

And why is this important?

1:26

Because it's actually also displaced and flipped itself underneath

1:31

the adductor API neurosis, as we can see right here. Okay?

1:35

This little, uh, dark structure right here. Okay.

1:39

And why is that important? This, this is, this is a, uh, called a,

1:43

so-called Stenner lesion, uh, originally de described by Dr. Stenner.

1:47

I believe it was. For those that are interested in JBJS,

1:51

I believe it was in the sixties or seventies, that article,

1:55

that seminal article. But you can see here, and you can imagine, okay,

1:59

that because the adductor a neurosis is interposed between

2:05

the site where the ligamentous, uh, uh,

2:08

fibers should be attaching.

2:10

It's gonna be difficult for those ligaments to flip back

2:16

into place because of that impediment, okay?

2:19

Preventing adequate healing and therefore instability of this

2:24

joint. And, uh, unfortunately, uh,

2:27

if left undiagnosed can progress to obviously instability, pain and,

2:31

uh, early osteoporosis of the first metacarpal pharyngeal joint. Now,

2:36

there is a corollary in other, um, joints of the body.

2:41

There is a standard like lesion, uh,

2:43

for instance in the knee where you have the tibial collateral ligament

2:48

or the MCL, whatever terms you use,

2:51

that tears distally in a similar fashion and flips proximally.

2:56

And then now it cannot get

2:59

Back to its, uh, original attachment site because the pe the pez,

3:04

an seine tendons are interposed between the torn distal MCL

3:09

and the uh, uh, proximal aspect of the tibia.

3:14

So just be aware,

3:15

there are centerlike lesions in other joints of the body

3:19

extrapolated from stent or stent's originally.

3:23

Description at the thumb when you have a ligament

3:28

or, or a fracture or, or injury, that does not reduce, well, the,

3:33

the, the main teaching point to take from this case and other such cases,

3:37

okay, in other joints, is you want to think about getting advanced imaging.

3:42

Because if you have a ligament or a piece of bone perhaps,

3:46

or maybe a cartilage flap or that's turned on itself, or a periosteum in a,

3:51

particularly in a kid that's, uh,

3:53

invaginated and interpose between the interpose itself,

3:57

between the two structures that need to heal, right?

4:01

That won't heal adequately,

4:03

and those candidates are typically gonna be surgical candidates. And, uh,

4:07

our surgeons need to go in there to alleviate that impediment to

4:12

allow proper healing between, uh, the torn ligament,

4:17

let's say. And, and its original, uh, bony insertion site.

4:22

So this is just a nice case of the standard lesion. And as you can see here,

4:27

this has also been likened to a yo-yo sign. Okay?

4:31

And the yo-yo, I guess being the, uh, the, the string of the yo-yo,

4:36

uh, sometimes being the adductor apa neurosis, but I've also see and,

4:41

and the torn and approximately displaced or flipped ligamentous fibers being

4:46

the actual yo-yo itself.