Osteoarthritis

Osteoarthritis is the most common type of arthritis (a condition that affects your joints). Healthcare providers sometimes refer to it as degenerative joint disease or OA. It happens when the cartilage that lines your joints is worn down over time and your bones rub against each other when you use your affected joints.

Usually, the ends of bones in your joints are capped in a layer of tough, smooth cartilage. Cartilage is like a two-in-one shock absorber and lubricant — it helps the bones in your joints move past each other smoothly and safely. If you have osteoarthritis, the cartilage in your affected joints wears away over time. Eventually, your bones rub against each other when you move your joints.

Osteoarthritis can affect any of your joints, but most commonly develops in your:

• Hands.
• Knees.
• Hips.
• Neck (cervical spine).
• Lower back (lumbar spine).

Types of osteoarthritis

A healthcare provider might classify osteoarthritis as one of two types:

• Primary osteoarthritis is the most common form of osteoarthritis that develops in your joints over time. Experts think it’s usually caused by normal wear and tear of using your joints throughout your life.
• Secondary osteoarthritis happens when something directly damages one of your joints enough to cause osteoarthritis. Injuries and traumas are common causes of secondary osteoarthritis. Other types of arthritis can damage the cartilage in your joints enough to cause osteoarthritis, too.

How common is osteoarthritis?

Osteoarthritis is very common. Experts estimate that more than 80% of adults older than 55 have osteoarthritis, even if some of them never experience symptoms.

Around 60% of people with osteoarthritis have symptoms they can notice or feel.