How does rheumatoid arthritis affect bone density?

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How does rheumatoid arthritis affect bone density?

Rheumatoid arthritis affects bone density in three ways: focal

subchondral and periarticular erosions, periarticular osteopenia, and

generalized osteopenia.

Focal subchondral and periarticular erosions. Rheumatoid arthritis is

characterized by synovial tissue proliferation. It is thought that

mononuclear cell precursors located within inflamed synovial tissue are

induced to differentiate into osteoclast-like cells that cause focal

osteolysis. This process, along with cytokine and macrophage activity,

results in the bone " erosions " typically seen on X-ray.

Periarticular osteopenia. The inflammatory synovial process also seems

to extend into periarticular bone and marrow. Increased numbers of

osteoclasts, macrophages, and lymphocytes, in conjunction with decreased

joint mobility, are thought to be responsible for the periarticular

osteopenia observed in rheumatoid arthritis patients.

Generalized osteopenia. This phenomonon is fairly well-documented,

although the exact mechanism remains unclear. Some studies indicate

decreased bone formation; others indicate increased bone resorption. The

mechanism is likely to be multifactorial, including inflammatory

mediators and reduced mobility. Generalized osteopenia is also seen

in other inflammatory diseases, such as systemic lupus erythematosis,

and Crohn's disease.

Source:

http://osteoed.org/faq/secondary/rheumatoid.shtml