What Is Knee RA?
Rheumatoid arthritis of the knee causes the joints to become tender, warm, and swollen. Although knee osteoarthritis causes pain and stiffness, joint pain with knee RA is more severe. Normally, a small pouch covered with a thin tissue called synovium lies between the two pieces of joint cartilage. Cartilage is a material that covers the ends of joint bones. Cartilage helps to keep bones from rubbing against each other during movement. The synovium secretes a liquid. This liquid helps keep joints lubricated. When joints are well lubricated, they move smoothly and painlessly. Inflammation of the synovium leads to damage and permanent destruction of the joint.
