What Is Osteoarthritis?

There are about 100 different types of arthritis. In general, arthritis means inflammation or swelling of 1 or more joints. A joint is a point in the body where 2 or more bones come together. Arthritis may also cause problems in the tissue near the joints, including muscles, tendons, and ligaments. And in some types of arthritis, the entire body can be affected.

Osteoarthritis (OA) is sometimes called degenerative joint disease, or wear-and-tear arthritis. It's the most common type of arthritis. In OA, the cartilage wears away. Cartilage is a slick tissue that covers the ends of the bones. It acts as a cushion and allows them to glide smoothly against each other. When the cartilage wears away, bone rubs against bone. This causes pain, swelling, stiffness, and trouble moving. Risk factors for developing OA include obesity, being older than 40, past joint trauma, concomitant inflammatory arthritis, repetitive joint use, and a family history of OA.

Front view of normal knee.
Normal knee
Front view of knee showing osteoarthritis.
Knee with osteoarthritis


OA can affect any joint. Weight-bearing joints, such as the hips and knees, are often affected. Common symptoms are joint pain and stiffness. Pain and stiffness may get worse with inactivity or overuse. For example, you may have more stiffness first thing in the morning, usually for less than 30 minutes. Or you may have stiffness after sitting for a long time. This might be while sitting at a movie. You may also have more pain in your hips or knees if you walk farther than you normally do.

Other common symptoms are:

  • Weak muscles

  • Unstable or wobbly joints

  • Grinding or crackling noises with motion

  • Joints with swelling or bumps

  • Unable to bend and straighten joints (reduced range of motion)

If you have any of these joint changes, make an appointment to see your healthcare provider. You can work together to create a treatment plan that may help lessen your pain and stiffness, and prevent symptoms from getting worse.

© 2000-2022 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.