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15-year-old boy,

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Salter-Harris injury.

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Question mark.

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Football injury, two days ago.

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Pain and swelling in the left knee.

0:09

Evaluate for meniscus or ACL tear.

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Okay, let's stay consistent.

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Let's go right to the axial.

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We're drilling through the axial because

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that's what came up first.

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Let's make it a little bigger.

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The patella is drifting a little bit.

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Don't like that, especially in a child.

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So, the child's going to have some

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patellofemoral maltracking

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because the child isn't even standing up.

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The knee isn't flexed,

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so they probably have some element of maltracking.

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It's quite a bit of swelling anteromedially.

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Let's check out the TTTG distance,

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just for giggles.

0:54

So, there's the trough of the trochlea.

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Vikram had a good question earlier

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about measurements.

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This is the one measurement I would do in a child.

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So, let's go right over to the tibial tubercle.

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And our measurement is

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1.4 getting up there.

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So, the TTTG distance is at the upper limits of normal.

1:18

How about our ACL?

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Nice and straight and black.

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Although, there's this funny little ridge

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in the femoral notch,

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which may weigh heavily when the

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patient is 40years of age.

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That can produce a problem for the ACL.

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There's some subtle notch stenosis anteriorly.

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The ACL doesn't like that,

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so that could be a cause of an

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ACL injury later on in life.

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There's the PCL.

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Seems a little bit dusky right there.

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We'll check it out in another projection.

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Here's our MCL.

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Looking good.

1:51

Here's our LCL.

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Looking good.

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Let's go down to our tibial tubercle again.

1:58

A lot of swelling right there.

1:59

That should not be there.

2:01

Some irregularity of the anterior surface.

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So they said,

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you know, know evaluate for Salter-Harris injury,

2:09

and they told us what to look for.

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Let's pull down our water weighted images.

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Let's stay with the same approach.

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Let's start with a sagittal posterolateral corner.

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Fine.

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Little bit swollen back there,

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but fine, otherwise.

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Posteromedial corner,

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there's our direct head of the semimembranosus.

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Remember, it was up here in the last case,

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so that one's not pulled off.

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There's our meniscocapsular reflection

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There is no posterior displacement

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of the medial meniscus.

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There's no failure of the brake stop mechanism.

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There's no ramp lesion.

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There's no anterior cruciate ligament rupture.

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Yes,

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it's a little bit,

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a little bit ill defined there.

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We better check it out on the T2

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and make sure it's okay.

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In fact, let's do it right now

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just to be complete.

2:58

And it's intact.

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So, that was a little volume averaging

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phenomenon there.

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And it's a bit swollen, but it's intact.

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There's no abnormal translation,

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so that isn't the problem.

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The PCL is intact.

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It's a little gray because the knee is an extension,

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so the PCL is a little bit wavy.

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We're getting a little artifactual

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magic angle phenomenon.

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Let's return to our water weighted image.

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Our growth plate,

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15 years old,

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we would expect it to be open,

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and it is in the femur.

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Our growth plate in the tibia,

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we would expect it to be open, and it is.

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But look at the difference

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in the two growth plates.

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This one is pretty dark,

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except for this bright area right here.

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There.

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That is the spongiosis zone of the metaphysis.

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Even this right here,

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this is where blood vessels come in.

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Now,

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if you go from the epiphysis to the metaphysis,

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you've got a group of layers.

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You got the germinal layer,

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the proliferative layer, the hypertrophic layer,

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and finally,

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the zone of provisional calcification,

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or ossification,

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which is what you're seeing here.

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So, these are blood vessel loops that create

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this ill defined, waxy,

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wax on, wax off appearance

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of high signal adjacent to the ossified growth plate,

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the ossified zone of the growth plate

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due to blood vessels.

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That is different than this.

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Intrasubstance within the physis,

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it's too bright.

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And then, you also have a little vertical

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signal in the back.

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Right here.

4:46

Right there.

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Let's put up the T1.

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We'll come back to this coronal image in a moment.

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And there's a tremendous amount of swelling here,

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especially as the pes anserine

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wraps around and inserts on the tibia.

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And that is very curious.

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What do you think that might be?

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That is periosteal elevation.

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We have a huge problem here in this child.

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And then, we have that high signal.

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Again, very disparate-looking.

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Spongiosis zone, ill-defined,

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too well-defined,

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too high a signal in the growth plate of the tibia itself.

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Elevation of the periosteum from blood.

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There is subperiosteal hemorrhage.

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One of your next jobs is to make sure

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no periosteum is stuck in there.

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Let's do that.

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Put up the T1

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and let's scroll them together

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at about the same size.

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So, look how much different the growth plate

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of the tibia looks than the femur.

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Too fat,

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too gray,

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too wide.

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Getting wider anteriorly,

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dissecting into the tibial tubercle portion

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of the apophyseal attachment.

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So, it's going all the way from here

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to here,

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to here.

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And there's also involvement of

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the posterior metaphysis.

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So, this is going to be a Salter-Harris injury

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that is higher grade.

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Please mute yourself if you can.

6:33

So, it's not a Salter-Harris one,

6:36

right?

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When you got a metaphyseal fragment,

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it's going to be a Salter-Harris two.

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If it involves the epiphysis,

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it's a Salter-Harris three.

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If it goes all the way through,

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it's a four.

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If it crushes the growth plate,

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it's a five.

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You have to be very careful because these are

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x-ray Salter-Harris designations.

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On MRI,

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you're going to see contusions in everybody.

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So everybody that has a Salter-Harris one,

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they're going to have a contusion.

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That is not the equivalent of a fracture.

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This linear,

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well-defined, vertical area of separation,

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that is a fracture.

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So you must learn to recognize macro fractures,

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which are included in the Salter-Harris grading system

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from microtrabecular injuries,

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which are not included

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in the Salter-Harris grading system.

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So, one of the tip offs that you're dealing with a

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true fracture and not the metaphyseal spongiosa,

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or maybe one growth plate is closed and the other

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one's open, and they look asymmetric,

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is the periosteum.

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Once you have seen periosteal bleeding,

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you know you have a fracture.

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Look at this massive periosteal hemorrhage.

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Right here.

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And also, look right there.

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Look right there.

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That is a piece of periosteum that is dipping

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right into the fracture space.

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Hard to see on the T1 weighted image.

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Let's go back to the coronal image for a minute.

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Now, there are a couple of zones here that are

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probably board-worthy,

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one is called the Latarjet zone,

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and one is called the Ring of La Croix,

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and another one is called the zone of Ranvier.

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If there are any residents on,

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I would google those.

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You'll probably get asked those in your core exam

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or maybe in your second exam.

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They are areas of growth plate anatomy.

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I think that's a little much for us today,

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but all you need to know is there is

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a periosteal sleeve right here,

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and that periosteal sleeve, disrupted.

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Blood underneath, blood on top,

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and there's the piece of periosteum,

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right there,

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that got stuck inside the fracture.

8:57

The menisci were normal.

8:59

The cruciate,

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even though there is this little signal,

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it was volume averaging.

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On the next cut, it's intact.

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So the anterior cruciate ligament was intact.

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There were no other major injuries in this case.

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It was a Salter-Harris two fracture.

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There was periosteal entrapment.

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There was also some injury to the deep fibers of

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the patellar tendon. You can see that right here.

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There is an ununited tibial apophysis.

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So there was pre existing oskid

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schlotters syndrome,

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and the patient had an injury

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to the pests and serenus.