Arthritis

  1. Home
  2. Health
  3. Arthritis

The Cause of Knee Pain: Step-By-Step

By Carol & Richard Eustice, About.com

Updated: August 28, 2006

About.com Health's Disease and Condition content is reviewed by the Medical Review Board

3 of 5

Step 3 of 5 - Inflamed Synovium (Rheumatoid Arthritis)

Cut section view of knee joint - rheumatoid arthritis

Cut section view of knee joint - rheumatoid arthritis

Photo © ADAM

In rheumatoid arthritis the body attacks its own joints. White blood cells, the agents of the immune system, travel to the synovium and cause inflammation (synovitis). The inflamed synovium causes warmth, redness, swelling, and pain.

During inflammation, the synovium thickens and makes the joint puffy and swollen. As rheumatoid arthritis progresses, abnormal synovial cells invade and erode cartilage and bone within the joint. Surrounding muscles, ligaments, and tendons weaken.

  • Rheumatoid Arthritis Screening Quiz
  • Test Your Knowledge: Rheumatoid Arthritis
  • Guide to Rheumatoid Arthritis
  • 3 of 5

    Explore Arthritis

    More from About.com

    About.com is accredited by the Health On the Net Foundation, which promotes reliable and trusted online health information.

    Arthritis

    1. Home
    2. Health
    3. Arthritis
    4. Joint Pain
    5. Knee Pain
    6. Inflamed Synovium - Rheumatoid Arthritis - The Cause of Knee Pain

    ©2009 About.com, a part of The New York Times Company.

    All rights reserved.