The word “arthritis” means “joint inflammation.” Inflammation is one of the body’s natural reactions to disease or injury, and includes swelling, pain, and stiffness. Inflammation that lasts for a very long time or recurs, as in arthritis, can lead to tissue damage.
A joint is where two or more bones come together, such as the hip or knee. The bones of a joint are covered with a smooth, spongy material called cartilage, which cushions the bones and allows the joint to move without pain. The joint is lined by a thin film of tissue called the synovium. The synovium’s lining produces a slippery fluid called synovial fluid that nourishes the joint and helps reduce friction. Strong bands of tissue, called ligaments, connect the bones and help keep the joint stable. Muscles and tendons also support the joints and enable you to move.
With arthritis, an area in or around a joint becomes inflamed, causing pain, stiffness and, sometimes, difficulty moving. Some types of arthritis also affect other parts of the body, such as the skin and internal organs.
What Causes Arthritis?
There are many different types of arthritis and the cause of most types is not known. It’s likely that there are many different causes. Researchers are examining the role of genetics (heredity) and lifestyle behaviors in the development of arthritis.
Although the exact cause of arthritis may not be known, there are several risk factors for arthritis. (A risk factor is a trait or behavior that increases a person’s chance of developing a disease or predisposes a person to a certain condition.) Risk factors for arthritis include:
Age. The risk of developing arthritis, especially osteoarthritis, increases with age.
Gender. In general, arthritis occurs more frequently in women than in men.
Obesity. Being overweight puts extra stress on weight-bearing joints, increasing wear and tear, and increasing the risk of arthritis, especially osteoarthritis.
Work factors. Some jobs that require repetitive movements or heavy lifting can stress the joints and/or cause an injury, which can lead to arthritis, particularly osteoarthritis.