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<v ->Let's move on now to osteoarthrosis.

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And I'll spend a little bit of time

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talking about osteoarthrosis and here a number of tissues

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are involved including synovium, cartilage bone,

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and other abnormalities.

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There's a beautiful picture of a sagittal section

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through the knee showing you

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all the classic findings of osteoarthrosis.

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Cartilage loss, meniscal pathology, bone sclerosis

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subchondral cyst, intraarticular bodies, osteophytes,

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and also synovial proliferation.

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Synovitis does occur in OA.

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So some people will not use the term osteoarthrosis

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but will use the term osteoarthritis.

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I still use the term osteoarthrosis whenever I can.

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We're gonna go ahead and look at some of these findings.

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The first is you should be aware

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of two classification systems that are used

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to describe abnormalities of the cartilage that occur in OA.

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The first of these is known

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as the outer bridge classification system,

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and it's based on what is seen by direct observation

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or during surgery or arthroscopy.

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Classically there are four grades of abnormality.

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I show you pictures taken from the literature

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and a description of what those grades are,

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but the higher the grade, the more severe the abnormality

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in the outer bridge classification.

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The second classification system

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is that of the international cartilage repair society.

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And indeed it is based on the depth

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of the cartilage abnormality.

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Grade zero being normal and at the other end of the spectrum

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a full thickness cartilage defect exposing the bone.

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So, that is a second system that is used.

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Now I know, and I'll get back to this tomorrow

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or during the lectures that some people use chondromalacia

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as their description

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of cartilage abnormalities in osteoarthrosis.

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And orthopedic surgeons may say Grade 3 chondromalacia

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or Grade 4 chondromalacia.

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In my view that is a poor term

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for the cartilage abnormalities

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that occur in osteoarthrosis.

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And I'll talk more

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about why I don't like that term tomorrow.

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There are a lot of other terms that we use

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to describe pathology of cartilage.

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I'm gonna go into detail tomorrow about what they need

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but chondral fissuring are these kind of these crevices

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and that occur they're often longitudinal,

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or longitudinal oblique a variable depth.

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And when we look at them sometimes on MRI

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we'll see a region of low signal,

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and this is one of the classic locations.

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The central aspect of the cartilage of the tropia.

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And this is highly specific

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for something that would look like this.

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This is kind of full thickness chondral fissuring,

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a fissure representing a split or crack

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that is long and narrow.

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Chondral loss obviously we know what that simply means

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loss of cartilage decrease in size, volume, and/or thickness

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but I wanted to point out something

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about chondral loss in that it looks different

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when you compare traumatic loss of cartilage

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versus degenerative loss.

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With traumatic loss you often deal

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with a defect that has sharp peripheral margins

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as you can see here.

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When you deal with degenerative loss

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of articular cartilage,

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the marginal areas that you can see here

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are more sloped and gradual.

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So that's a way that you can tell the two apart.