Ankylosing Spondylitis (AS) causes inflammation around joints and the growth of syndesmophytes that may eventually fuse vertebrae. I'm familiar with the genetics (HLA-B27, IL1A) related to the condition, but I can't find any information about the mechanism that causes the actual growths to occur.

My current assumption is that AS causes the over-production or under-production of a particular compound or enzyme at the growth site, but I can't find any studies or papers that explain this. Is the mechanism known? Is it directly related to abnormal levels of a particular substance?


As far as I remember the pathology course from medical school, chronic long-lasting inflammation often leads to proliferation of connective tussie and ultimately to fibrosis.

The actual mechanism here is the lack of oxygen which is used-up by different immune system cells to produce peroxydes and superoxydes.

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  • $\begingroup$ Interesting. So the symptomatic inflammation over long periods of time ultimately causes fibrosis and fuses the vertebrae? Also, what causes the lack of oxygen at the site? $\endgroup$ – Polynomial Apr 12 '12 at 13:49
  • $\begingroup$ Not only symptomatoc, any inflammation (including the idiopatic one) would do. There are many reasons for hypoxie here: decreased blood flow rate, swelling etc. $\endgroup$ – Alexander Galkin Apr 12 '12 at 15:57

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