Arthritis Basics

What Is Arthritis?

Arthritis is a general term for a group of more than 100 diseases. 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 enclosed in a fibrous casing called the synovium. The synovium's lining produces a slippery fluid -- called synovial fluid -- that nourishes the joint and helps limit friction within. 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.

Types of Arthritis

There are more than 100 different types of arthritis. Some of the more common types include:

• Osteoarthritis. This is the most common type of arthritis. It occurs when the cartilage covering the end of the bones gradually wears away. Without the protection of the cartilage, the bones begin to rub against each other and the resulting friction leads to pain and swelling. Osteoarthritis can occur in any joint, but most often affects the hands and weight-bearing joints such as the knee, hip and facet joints (in the spine). Osteoarthritis often occurs as the cartilage breaks down, or degenerates, with age. For this reason, osteoarthritis is sometimes called degenerative joint disease.

• Rheumatoid arthritis. Rheumatoid arthritis is a long-lasting disease that can affect joints in any part of the body but most commonly the hands, wrists, and knees. With rheumatoid arthritis, the immune system -- the body's defense system against disease -- mistakenly attacks itself and causes the joint lining to swell. The inflammation then spreads to the surrounding tissues, and can eventually damage cartilage and bone. In more severe cases, rheumatoid arthritis can affect other areas of the body, such as the skin, eyes, and nerves.

• Gout. Gout is a painful condition that occurs when the body cannot eliminate a natural substance called uric acid. The excess uric acid forms needle-like crystals in the joints that cause swelling and severe pain. Gout most often affects the big toe, knee and wrist joints.

What Are the Symptoms of Arthritis?

Different types of arthritis have different symptoms and the symptoms vary in severity from person to person. Osteoarthritis does not generally cause any symptoms outside the joint. Symptoms of other types of arthritis may include fatigue, fever, a rash and the signs of joint inflammation, including:

• Pain
• Swelling
• Stiffness
• Tenderness
• Redness
• Warmth

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.

How Common Is Arthritis?

Arthritis is very common. It has been estimated that as many as 70 million Americans -- or about one in three -- have some form of arthritis or joint pain. It is a major cause of lost work time and serious disability for many people. Osteoarthritis, the most common form, affects more than 20 million Americans. Arthritis affects people of all ages, but is more common in older adults.

How Is Arthritis Diagnosed?

Osteoarthritis is typically diagnosed with a complete medical history, including a description of your symptoms, and physical examination. Imaging techniques—such as X-rays or magnetic resonance imaging (MRI)—are sometimes used to show the condition of the joints. If other types of arthritis are suspected, laboratory tests on blood, urine and/or joint fluid may be helpful in determining the type of arthritis. These tests also can help rule out other diseases as the cause of your symptoms.

How Is Arthritis Treated?

The goal of treatment is to provide pain relief and increase joint mobility and strength. Treatment options include medication, exercise, heat/cold compresses, use of joint protection and surgery. Your treatment plan may involve more than one of these options.

What Is the Outlook for People With Arthritis?

With early diagnosis, most types of arthritis can be managed and the pain and disability minimized. In addition, early diagnosis and treatment may be able to prevent tissue damage caused by arthritis. Early, aggressive treatment is particularly important for rheumatoid arthritis in order to help prevent further damage and disability down the road.

Can Arthritis Be Prevented?

Although it may not be possible to prevent arthritis, there are steps to take to reduce your risk of developing the disease and to slow or prevent permanent joint damage. These include:

• Maintaining a healthy weight. Excess weight puts strain on your joints.
• Exercising. Keeping your muscles strong can help protect and support your joints.
• Using joint-protecting devices and techniques at work. Proper lifting and posture can help protect your muscles and joints.
• Eating a healthy diet. A well balanced, nutritious diet can help strengthen your bones and muscles.