Osteoarthritis is best described as which of the following?

• A. Autoimmune arthritis resulting in joint destruction.
• B. Breakdown of protective cartilage on the ends of bones, causing bones to rub together.
• C. Infection of the joint cavity leading to swelling.
• D. Dislocation of a joint due to trauma.

Answer: (B)

Osteoarthritis is a degenerative process where the protective cartilage at the ends of bones wears away, so the bones rub directly against each other. This explains the typical symptoms of joint pain with use, stiffness after periods of inactivity, and reduced range of motion, as the smooth cartilage surface is lost and the joint space narrows. It’s largely due to wear-and-tear and age-related changes, and while some inflammation can occur, OA isn’t driven by an autoimmune attack like some other arthritis forms.

The other options describe different problems: autoimmune arthritis involves the immune system attacking joints and causing inflammation; septic arthritis is an infection of the joint with fever and swelling; a dislocation is a traumatic displacement of the joint. These do not capture the characteristic cartilage loss and bone-on-bone contact seen in osteoarthritis.