Osteoarthritis -

Osteoarthritis (OA) is the most common chronic (long-lasting) joint condition.
A joint is where two bones come together. The ends of these bones are covered with protective tissue called cartilage. With OA, this cartilage breaks down, causing the bones within the joint to rub together. This can cause pain, stiffness, and other symptoms.

OA occurs most often in older people, although it can occur in adults of any age. OA is also called degenerative joint disease, degenerative arthritis, and wear-and-tear arthritis.

What Are Osteoarthritis Causes?

The causes of arthritis depend on the form of arthritis. Causes include injury (leading to degenerative arthritis), abnormal metabolism (such as gout and pseudogout), inheritance (such as in osteoarthritis), infections (such as in the arthritis of Lyme disease), and an overactive immune system (such as rheumatoid arthritis and systemic lupus erythematosus).