0:01

That leads us into the epi of the boxer's knuckle.

0:06

So this is an epi used

0:07

to describe a traumatic sagittal band injury.

0:12

The long finger is most commonly involved.

0:14

And of course, the mechanism of here is

0:16

that somebody punches somebody else with the unprotected

0:20

hand, and you've got this metacarpal thal injury that leads

0:24

to a laceration

0:25

and ultimately that laceration extending to the level

0:29

of the metacarpal falange joint.

0:32

Well, in this case,

0:33

as you're looking at the metacarpal feal joint,

0:36

probably the least of this person's concerns

0:38

or the fact that they've got a sagittal band injury,

0:41

but you can see the extensor tendon, of course,

0:44

migrating away from the side of the sagittal band injury.

0:49

Here you're seeing all of the soft tissue distortion,

0:53

and when we think about, again, the laceration that occurs,

0:57

it's also been referred to as the fight bite.

1:01

The person who lost their tooth

1:04

or who has the bloody lip is

1:07

probably the lucky person in this case

1:09

because when you have this laceration,

1:11

particularly from the fight bite,

1:14

the potential complications can be substantial.

1:18

70% of human bites occur in the upper extremity,

1:21

and about 10% of those become infected.

1:24

That's a pretty high rate.

1:26

There can be a rapid progression of this inflammatory

1:30

and infectious process,

1:31

and it's due to a few different things.

1:33

The avascular nature of the tendon

1:35

and the MCP joint that limits the ability

1:38

to fight off infection.

1:40

And then of course, a high concentration

1:42

of pathogenic microorganisms in the human mouth.

1:46

And so here an example of the complication of

1:50

septic arthritis osteomyelitis, in this case

1:53

with a sinus track to skin surface

1:56

after that bite bite, these are T one fat sac post

2:00

contrast enhanced images, axial image, again, least

2:03

of this person's concern, the insufficient

2:06

or torn sagal band classic finding

2:09

of the tendon migrating away from the side of the tear.

2:13

Tiny little low signal intensity structures.

2:16

Those are little gas bubbles in this case,

2:18

in the post contrast image enhancing synovitis here.

2:22

Very little fluid, mostly synovial hypertrophy.

2:26

And when you look into the coronal imaging plane,

2:29

you've got a frank erosion.

2:31

We can see that in the axial plane as well

2:33

with enhancing marrow.

2:35

So the classic septic arthritis, osteomyelitis, sinus tract,

2:40

and sagittal band injury.

2:42

In this case of the fight bite.