Osteoarthritis is characterized by which of the following?

• A. An autoimmune disease causing joint inflammation.
• B. A progressive breakdown of joint cartilage, resulting in bones rubbing against each other.
• C. An acute bacterial infection of joints.
• D. Temporary joint swelling due to fluid.

Answer: (B)

Osteoarthritis is best understood as a degenerative joint disease where wear-and-tear leads to thinning and breakdown of cartilage. As the cartilage wears away, there’s less cushion between the bones, so the bones can rub against each other. That contact causes joint pain, stiffness with use, and reduced range of motion, and over time the joint space narrows with possible bone changes like osteophyte formation.

This matches the description of a progressive loss of cartilage and bone-on-bone contact. It’s not primarily an autoimmune inflammatory process (that would point to conditions like rheumatoid arthritis), nor is it an acute infection of the joint (septic arthritis), nor simply temporary swelling from fluid accumulation.