What is osteoarthritis?

• A. Osteoarthritis is an autoimmune disease primarily affecting bone marrow density.
• B. Osteoarthritis is an infection of the joint.
• C. A degenerative joint disease characterized by cartilage loss, joint space narrowing, osteophyte formation, and pain with movement.
• D. Osteoarthritis is temporary inflammation after injury.

Answer: (C)

Osteoarthritis is a degenerative wear-and-tear of joints. It starts with the loss of articular cartilage that cushions the ends of bones. As cartilage wears away, the joint space narrows, bones rub together, and bone spurs (osteophytes) form as the bone attempts to repair the damage. These structural changes lead to pain with movement, stiffness, and often reduced range of motion. OA tends to develop with aging and repetitive joint use, and can be worsened by factors like obesity or prior injury.

It is not an autoimmune disease attacking bone marrow or other tissues, so it doesn’t fit descriptions of autoimmune conditions. It isn’t an infection of the joint, which would present with red, hot, swollen joints and systemic signs like fever. It isn’t a temporary inflammation after injury, since osteoarthritis is a chronic, slowly progressive condition rather than a short-lived inflammatory response.