HOW TO IDENTIFY PERIOSTEALSTRIPPING ON MRI

Let’s start and we’re to look at ligament tears and periosteal stripping. Now ligament tears, I’m not going to go into the actual ligament tears themselves. This is all about you found a ligament tear, what more do you need to look at? And one of the things that you do need to look for is periosteal stripping and this is a pattern that we will see in a number of joints.

We’ve got a patient here who’s got a syndesmotic injury that’s a tear of the PITFL. What more do you need to look at? You can say in your report, can say it’s a torn PITFL. The referrer is probably going to be happy with it. But the thing is you need to do more. So the thing that happens with ligament attachments and also tendon attachments is that they attach to periosteum bone. So, sometimes instead of rupturing, what happens is that the periosteum itself gets lifted off the cortex. So that’s called periosteal stripping. And the way to understand that is if you look at this image here, so the dark yellow here is cortex, the lighter yellow is the periosteum. And there’s no plane in between them. They’re actually just of stuck together. And, this is a really lovely image because

this shows you is that this is the periosteum that’s been lifted off. They’ve cut it and lifted off and reflected it. And this is cortex underneath. But when we scan and we see periosteal stripping, this is what we see. We see a lifted off periosteum & we see cortex underneath it. And then the signal that we see, reflects this. So the normal periosteum edema, you can’t see it because the signal is exactly the same as cortex. So both are black on, this is a PDF headset, this is PD. So there’s a combination of periosteum and cortex here.

When you have periosteal stripping, there are two things that occur. One is because there’s trauma to the periosteum, you will get edema and hemorrhage. And when you see this pattern on the posterior margin, so someone has got a syndesmotic injury, if you see this pattern of edema and fluid tracking along the posterior margin of cortex almost for sure about periosteal stripping, this is what it does. It gives you this, track of fluid that goes along the back of the cortex or back of the tibia. The second thing to look at is to look at the actual periosteum. So now because the periosteum is not stuck to bone anymore, it’s been lifted off, you can now see it. So what we end up seeing is that we see two black lines. So here’s the cortical line and this really thin line here, that’s the strip periosteum. So now if I go back to this, This is what you’re seeing. So you’re seeing the thick black line of the cortex here and the thin black line of the lifted off periosteum here. Let’s go back to that MR. So thick cortex, thin periosteum.

What does that look like? So if we look at a scan here, so we’ve got a sagittal, I think this is a T2 fat sat. And as we scroll, what we end up seeing is that we’ve got a black line here, which is the then we have a second black line. Whenever in trauma, if you see two black lines, that means that it’s periosteal stripping and we also have edema as well.

This is really the key, when you see two black lines like this. And this is the space now that’s being created between the periosteum and the cortex that’s being lifted off.

If we look at this on the axial, so this patient’s had significant trauma, syndesmotic, sorry, syndesmotic injury. is completely torn. So it’s very severe trauma. But what we’re looking at here is actually the periosteum. So this is the periosteum that’s been lifted off anteriorly. And here’s the periosteum that’s been lifted off posteriorly. So you can see that the PTFL is still actually continuous.

All it’s done is that, the PTFL should be inserting around here. So instead it’s basically lifted, it’s still attached to the periosteum, but it’s just lifted it off and stripped it off the attachment to cortex.

So now this is not the only place we see it. We also see it virtually everywhere else, but very commonly we see this in the shoulder. So this pattern again, so we’ve got a labrum here. Here’s a labrum then you see cortex and then you see a second black line. So this is the periosteum that’s been stripped. So the labrum is still attached to the periosteum. So this is periosteum, this is labrum and it’s stripped off the attachment and then fluid is then tracking between stripped off periosteum and the cortex, which is exactly the same appearance that we saw just before in the ankle.

Okay, so for periosteal stripping, the key points are, one, in a normal scan, you don’t see the periosteum. But in the context of trauma, if you see a double, look for a double black line. The first thing is actually look for edema. Look for edema at the bone margins, because if you don’t have edema, you’re not going to have periosteal stripping in the acute stage. Once you see the edema, then look for the double black line. That tells you that that’s stripping of the periosteum.