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<v ->There is a clear relationship in the need

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between osteoarthrosis with cartilage

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and bone abnormalities, and meniscal abnormalities.

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Now we can argue which comes first.

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It's like, again, the chicken and the egg.

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I'm not entirely sure, perhaps they develop together,

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but there is no question

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that when you have OA

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in one of the femoral tibial compartments,

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it is likely that the adjacent meniscus is also abnormal.

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And the type of meniscal abnormality

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could be a meniscal tear

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or meniscal root ligament, simply meniscal extrusion

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where the meniscus moves away

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from the joint prior meniscal surgery.

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The classic tear that occurs owing

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to degeneration of the meniscus, is a free edge tear,

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the inner margin of the meniscus.

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And it is a longitudinal horizontal tear.

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Longitudinal because it has a circumferential dimension,

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horizontal because it tends to be a cleavage tear

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that eventually will divide the meniscus

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into two portions.

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Here showing you two examples

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of this sort of tear with adjacent cartilage abnormality.

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Whenever you have meniscal pathology,

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including as in the example at the top meniscal extrusion,

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you know there's abnormal stress

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being placed on the cartilage and bone in that compartment.

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Here we have an example

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of abnormality involving the inner margin

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of the posterior horn of the medial meniscus,

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and the posterior root ligament.

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Be this a radial tear

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of the meniscus or a root ligament tear,

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or detachment, meniscal extrusion has occurred.

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And owing to that, related to stress cartilage abnormalities

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and marrow edema develop in the sub Jason bone.

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In my experience,

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more often in the condyle than in the tibial plateau.

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Over time, an insufficiency fracture may develop

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in that condyle.

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I'm gonna talk a lot more about this tomorrow

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but here is what it looks like

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and this of course looks like osteoarthrosis,

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and in the old days we would call this SONK

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or spontaneous stenosis about knee.

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We'll get back to SONK tomorrow.