Joint disorders can cause pain, swelling, stiffness, and loss of motion in the joints. They often are caused by inflammation that can affect not only the joints, but also supporting structures of the body, such as muscles, tendons, ligaments, and bones.

Inflammatory disease are related to the immune system -- the body’s protection against invasion of infections and toxins. In these diseases, the immune system attacks the body’s own healthy cells, mistaking them for cells that do not belong. This causes inflammation of the lining or connective tissue of the joints, or other parts of the body.

Tumor necrosis factor (TNF) is one of the chemical messengers that helps regulate the inflammatory process. When the body produces too much TNF, it overwhelms the immune system’s ability to control inflammation in the joints.