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<v ->Hello everybody, and welcome back to the fourth day

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of our course dealing with synovial joints.

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Today I'm honored to be joined by Abdalla Skaf.

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I have to tell you a few things about him.

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He visited us quite a while ago,

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and I remember at the time

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that he came to San Diego from France,

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he had worked with Bernard Rojay in France.

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And as he arrived, he began to talk about MR

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imaging of the shoulder.

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And in fact, he wrote a spectacular paper on that subject.

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But the truth is, and I don't think I've ever told him this

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that I was so impressed with what he knew when he arrived

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that I started to actually study more

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at night than I had ever done before.

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Just so I would not look like a fool the next day.

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Very impressive.

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And of course now he is internationally known

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as a leader in MR imaging particularly that applied

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to the musculoskeletal system.

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So Abdalla, I really appreciate your joining us today.

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Now, as we look at the material that we're covering today

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you'll see it's not a long list at all.

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It relates to alterations in the Subchondral bone

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but let me tell you at the outset, these are complex topics.

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And therefore I do think there's a possibility.

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We will run a little bit long in this session.

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I apologize for that.

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If some of you have to leave before the end of the program

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but we have to do justice

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to these very, very important topics.

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One of the questions that's gonna come up

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during this particular presentation and four

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segments is gonna be the relationship

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between these conditions, transient, osteoporosis

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and its associated transient painful marrow edema

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versus subchondral insufficiency fractures

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versus osteonecrosis.

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And later on today,

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I will try to give you a scheme that shows you

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perhaps the way these three disorders are related

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but that's a little bit later in the program.

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Let's begin our discussion of transient osteoporosis.

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We'll talk about it.

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It's relationship to transient marrow edema.

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And we'll also then go on

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and talk a little bit initially

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about insufficiency fractures.

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I'll return to the last of those later on in the talk .

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We have to know a little bit

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about the terminology that we will be using.

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So I'm gonna use this particular slide to introduce

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that terminology to you.

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Osteoporosis is a term that we use qualitatively normal

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but quantitatively deficient bone.

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Osteomalicia is the term we use

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for decreased bone mineralization with a presence

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of non mineralized osteoid seams.

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And osteopenia

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I think is a term that was introduced

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by Radiologists who had trouble distinguishing

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between such conditions as osteoporosis and osteomalicia.

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So they came up with a term that kind of covered both.

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It simply means increased radiolucency of bone.

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But if you're an astute observer you can look at the images,

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even with conventional radiography

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and try to make a distinction

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between osteoporosis and osteomalicia.

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We just look at the spine for example, here,

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and we can see those differences.

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When we deal with osteoporosis,

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One of the things we look for is accentuation

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of the vertical trabeculae

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within the vertebral body.

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The second thing we look for

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is a compression of the of the vertebral body.

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And typically it occurs more

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on one side than on the opposite side.

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And the final characteristic when osteoporosis

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involves a vertebral body

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is one vertebral body may be involved

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more than its neighbor.

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And in fact its neighbor may be entirely normal.

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When you compare that to what we see with osteomalicia

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typically all vertebral bodies are involved

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to about the same extent, the depression of these end plates

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pretty much the same at the top and bottom

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of each vertebral body.

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And each vertebral body looks very very similar

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to the adjacent vertebral body.

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So there are ways in fact, to tell apart osteoporosis

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and osteomalicia.

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Now at the outset I also wanna introduce again

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I mentioned it earlier in the course

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this new terminology of edema like marrow change.

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And that is because we often use the word

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marrow edema to cover a number

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of histological alterations that may include marrow edema

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but include other things as well,

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such as bone remodeling or bone formation

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or bone re absorption or fibrosis necrosis.

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So I just would like you to realize that at the beginning

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Now edema like marrow changes, four words.

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It takes a while.

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So I will apologize at the beginning

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of this lecture to indicate I'm probably going to

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use the word edema in instances where purists say

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I should use the word edema-like marrow change here.

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You can see an example of what looks to be marrow edema,

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in a patient who has osteoporosis involving the knee.

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This edema involving the tibial plateau.

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But histologically this may not be just marrow edema.

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There may be other histologic findings as well.

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Now, when we talk about osteopenia,

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and specifically when we categorize it as osteoporosis,

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we can classify it according to its distribution.

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One would be generalized

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and that would indicate that we're dealing

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with osteopenia, many many bones

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classically more dominant in the axial skeleton.

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There are a number of causes for that.

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I've listed them here.

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I'm not gonna read them at this time.

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The second type would be regional.

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Typically we're talking

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about osteopenia involving one or more extremities.

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Here are the number of entities that we are listing,

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not as many, we're gonna be talking about some of them today

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And finally localized osteopenia, which tends to occur

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about other processes involving the skeleton.

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So about cases of arthritis, infection, tumors

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there may be areas of osteopenia as well.

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For our discussion today at the beginning

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this is the category.

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We're gonna talk

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about entities that produce transient osteopenia and

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as we'll soon, see a also transient painful marrow edema.