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How does rheumatoid arthritis damage the joints?

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immune system disorder False-color scanning electron micrograph of a T cell infected with HIV (human immunodeficiency virus), the agent that causes AIDS (acquired immunodeficiency syndrome).

Rheumatoid arthritis is an autoimmune disorder that causes chronic inflammation of the synovial membranes, the tissues that line and lubricate the joints.12

This inflammation leads to the following destructive processes:

Pannus Formation: The synovial membranes thicken and develop into a layer of roughened granulation tissue called pannus, which protrudes over the surface of the articular cartilage.1
Cartilage and Bone Erosion: Underneath the pannus, the cartilage is eroded and destroyed. In severe cases, large areas of bone may be stripped of cartilage, leading to the formation of adhesions between joint surfaces.12
Ankylosis and Deformity: These adhesions can transform into fibrous or bony tissue, causing the joint to become fixed in place (ankylosed). This process, along with the weakening of supporting tendons and ligaments, leads to joint instability, displacement, and permanent deformity.12

Ultimately, this damage interferes with joint mobility and can result in significant disability.12