What is arthritis?

Arthritis is a disease that affects your joints (areas where your bones meet and move). Arthritis usually involves inflammation or degeneration (breakdown) of your joints. These changes can cause pain when you use the joint.

Arthritis is most common in the following areas of the body:

• Feet.
• Hands.
• Hips.
• Knees.
• Lower back.

What are the parts of a joint?

Joints get cushioned and supported by soft tissues that prevent your bones from rubbing against each other. A connective tissue called articular cartilage plays a key role. It helps your joints move smoothly without friction or pain.

Some joints have a synovial membrane, a padded pocket of fluid that lubricates the joints. Many joints, such as your knees, get supported by tendons and ligaments. Tendons connect muscles to your bones, while ligaments connect bones to other bones.

What are the different types of arthritis?

Arthritis is a broad term that describes more than 100 different joint conditions. The most common types of arthritis include:

Osteoarthritis, or “wear and tear” arthritis, which develops when joint cartilage breaks down from repeated stress. It’s the most common form of arthritis.

Juvenile arthritis (JA), a disorder where the immune system attacks the tissue around joints. JA typically affects children 16 or younger.

Gout, a disease that causes hard crystals of uric acid to form in your joints.

Psoriatic arthritis, joint inflammation that develops in people with psoriasis (autoimmune disorder that causes skin irritation).

Rheumatoid arthritis, a disease that causes the immune system to attack synovial membranes in your joints.

What causes arthritis?

Different types of arthritis have different causes. For instance, gout is the result of too much uric acid in your body. But for other types of arthritis, the exact cause is unknown. You may develop arthritis if you:

• Have a family history of arthritis.
• Have a job or play a sport that puts repeated stress on your joints.
• Have certain autoimmune diseases or viral infections.

What are the symptoms of arthritis?

Different types of arthritis have different symptoms. They can be mild in some people and severe in others. Joint discomfort might come and go, or it could stay constant. Common symptoms include:

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

How is arthritis diagnosed?

If you think you may have arthritis, see your healthcare provider. The provider will ask about your symptoms and learn how joint pain affects your life. Your provider will perform a physical exam, which may include:

• Assessing mobility and range of motion in your joints.
• Checking for areas of tenderness or swelling around your joints.
• Evaluating your overall health to determine if a different condition could be causing your symptoms.