The word arthritis means a swelling of the body joints, but not all arthritis involves swelling. In the type of arthritis known as rheumatism, the joints do swell up and eat into the cartilage that surrounds them.
Since this cartilage acts as a sort of “shock absorber” around the joint, the loss of cartilage and of certain minerals in the bones results in a stiff joint, which makes movement painful.
The kind of arthritis that older people often get is known as degenerative, and is different. It is simply a product of old age. In this disease, the cartilage around the joint wears away, and the bones underneath the cartilage then come in contact with one another, producing pain whenever the joint moves.
While scientists know the causes of degenerative arthritis, they still aren’t sure what causes rheumatism.