0:00

<v ->Now I wanna mention that,

0:02

although the classic distribution of septic arthritis

0:07

is monoarticular, that is a great rule.

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Sometimes two adjacent joints are involved

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and it leads the observer away from infection

0:19

because it's more than one joint.

0:21

(coughs) But you should recognize that this is almost

0:24

like pseudo-polyarticular.

0:27

Remember I've shown you rheumatoid arthritis,

0:30

you've seen now for the third time,

0:32

but this could be a septic arthritis as well.

0:36

And the fact that also the AC joint is involved

0:39

doesn't mean that it is truly polyarticular.

0:43

This is really a monoarticular process

0:47

that now has spread into the bursa

0:50

and has reached the acromioclavicular joint.

0:53

And this is something you should be aware of.

0:55

Glenohumeral and acromioclavicular joint,

0:58

knee with extension to the proximal tibiofibular joint,

1:03

ankle to the posterior subtalar joint,

1:05

hindfoot, midfoot involvement

1:07

and all the compartments of the wrist that may be involved.

1:12

Now, I also brought up the concern that infection,

1:15

septic arthritis classically monoarticular

1:19

can be polyarticular.

1:21

And the most common cause for that is rheumatoid arthritis.

1:25

And two or more joints certainly can be involved.

1:29

And I mentioned earlier on that the clinical diagnosis

1:33

is extremely difficult in these cases,

1:36

'cause it looks like an exacerbation

1:38

of the rheumatoid process alone.

1:42

This an example of proven rheumatoid arthritis

1:46

and septic arthritis.

1:48

Now I wanna just show you a couple of classic examples

1:52

of infections where the appearance on MR

1:55

gives you the entire diagnosis.

1:58

This is what Mycetoma looks like.

2:00

We see it most commonly in the foot called Madura foot.

2:04

But I know that some of the Brazilians listening,

2:07

I've seen it elsewhere,

2:08

I've received cases of Madura involvement

2:12

in the knee and elsewhere.

2:14

And one of the classic (indistinct)

2:16

that we look for shown here

2:18

is known as the dot-in-circle appearance.

2:22

You can see it is pathognomonic

2:25

of this particular type of infection.