Rheumatic diseases are by far the most commonly occurring chronic illnesses in this country—or in the world. In the United States there are twice as many people with rheumatic disease as have the next most common chronic ailment, heart disease.  Next to nervous and mental disease, rheumatism causes more days lost from work in our country than any other chronic disease.

Rheumatism is a general term used to describe stiffness and aching pain. Rheumatic diseases are those in which abnormalities are located in the supporting structures of the body, the ligaments, tendons, joints, muscles, and bones—the tough parts of the body.

The body is often regarded as a great aggregation of cells, all of which must be held together and supported by a framework. The framework is called connective tissue, and is mainly made of tough fibrous materials. Connective tissue is an appropriate name for this system since it does, in fact, connect the cells and the parts of the body together. When something goes wrong with the manufacture or the maintenance of the big molecules that make up the tough structures of the body, the result is aching, swelling, pain, stiffness and sometimes heat, redness, and gross inflammation.

Though most rheumatic diseases involve joints, many connective tissues other than joints are also affected.

There are about 50 different rheumatic diseases. Diagnosis of them is often difficult, requiring considerable study by a physician, many laboratory tests and x-rays. One reason for failure in treatment is that the particular type of rheumatic disease is not identified in the first place. One should not assume one has "arthritis" or "rheumatism" until his doctor has reached a decision regarding diagnosis and appropriate treatment. Some rheumatic diseases require little or no treatment; a few more serious varieties require very extensive and prolonged treatment.

The most common rheumatic diseases are rheumatoid arthritis, osteoarthritis and gout.  In addition there are the collagen diseases.