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<v ->The second lesion that occurs

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in the discovertebral junction, an ankylosing spondylitis,

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is known as the Andersson lesion.

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Easy to remember.

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A Anderson for A, all.

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Because it involves pretty much

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the entire discovertebral junction.

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Now, there's been many articles

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trying to figure out why we get this irregular surface,

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and what this tissue is.

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And there's some people believe that it relates

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to involvement of the adjacent facet joints.

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That as the facet joints

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are involved in ankylosing spondylitis,

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abnormal motion takes place at the discovertebral junction.

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And that abnormal motion leads to protrusion

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of disc material, into the vertebral body.

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You know it as Schmorl's nodes or cartilaginous nodes.

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Now, others disagree with this, and say,

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no, it's some sort of synovial like process

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that's going on here.

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They don't think it's kind of related to microtrauma

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and Schmorl's nodes.

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I'm not certain, because we haven't studied enough specimens

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with this, but I can tell you the resulting appearance

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can simulate Schmorl's nodes.

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And so, you may mistake them for Schmorl's nodes.

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And I'll talk more about that in a moment.

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But here's an example of a fairly long sagittal image

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of the thoracal lumbar spine.

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The sequence is STIR.

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We can see here, the Andersson lesion.

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At the bottom level here at this level,

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we see Romanus lesions, we see facet joint involvement here.

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Certainly a characteristic target site.

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Now, I wanna just to,

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I guess I had no other place to put this,

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and I have an interest in Schmorl's nodes,

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just to show you a few other diseases

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that lead to Schmorl's nodes.

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They're called Schmorl's nodes or cartilaginous nodes,

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and simply what they are, are portions of the disc,

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often the nucleus,

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that extend through the cartilaginous end plate

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to reach the subchondral bone.

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So, you can imagine that anything that weakens

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the cartilaginous end plate, or the subchondral bone,

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or both, will allow cartilaginous

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or Schmorl's nodes to form.

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Perhaps, the best one you know, of course, is trauma.

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A single episode or a stress related trauma,

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can lead to protrusion of disc material,

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not only into the spinal canal,

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but into the vertebral body producing.

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In fact, a cartilaginous node as in this particular example.

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We also see the same phenomena occurring

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with degenerative disc disease,

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because as the nucleus degenerates, all right?

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The cartilaginous end plates degenerate.

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And so, portions of the nucleus may make their way

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into the vertebral bodies, often surrounded by sclerosis.

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Those are cartilaginous nodes.

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With regard to developmental causes,

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we deal with Scheuermann's disease.

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Now you may know this past as a progressive

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thoracic kyphosis occurring in the adolescent,

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but you see Scheuermann's disease may isolate

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into the lumbar spine, or both,

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the thoracic and lumbar spine may be involved.

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And when it isolates in the lumbar spine, as shown here,

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it produces surface irregularity of the vertebral bodies

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and multiple Schmorl's nodes as shown in this example.

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And sometimes,

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it produces posterior limbus vertebral bodies as well.

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And then, just to prove subchondral bone resorption,

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involves the subchondral bone of the vertebral bodies.

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So, in patients with chronic renal disease,

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or higher risk for Schmorl's nodes,

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here with widening of the sacroiliac joint

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and symphysis pubis as well.