Osteoarthritis is characterized by which of the following?

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

Answer: (A)

Osteoarthritis is a degenerative, wear-and-tear process in which articular cartilage progressively breaks down. As cartilage is lost, the smooth cushion between bones disappears, and the ends of the bones begin to rub together, leading to pain, stiffness, and eventual narrowing of the joint space. This description—cartilage breakdown with bone-on-bone contact—best fits the condition being described.

The other scenarios reflect inflammatory or infectious processes rather than a primary degenerative wear-and-tear pattern. Temporary joint swelling due to fluid is more typical of acute inflammation or injury. Autoimmune inflammatory arthritis involves immune-driven joint inflammation, not the cartilage wear that characterizes OA. An acute bacterial infection of a joint (septic arthritis) presents with rapid onset and systemic symptoms like fever, along with a warm, swollen joint.