Which radiographic finding is most characteristic of osteoarthritis?

• A. Symmetric joint space narrowing
• B. Erosions with periarticular bone loss
• C. Asymmetric joint space narrowing with subchondral sclerosis and marginal osteophytes
• D. Uniform cartilage loss

Answer: (C)

Osteoarthritis shows degenerative changes that are typically uneven in a joint, reflecting focal cartilage loss and bone response. On radiographs, the hallmark is asymmetric joint space narrowing because cartilage wears away more on one side, often with the medial compartment affected first. This is accompanied by subchondral sclerosis, where the exposed bone thickens and becomes denser from increased load, and marginal osteophytes, which are bony projections at the joint margins formed as a reaction to surface irregularities. These features together—asymmetric joint space loss plus subchondral sclerosis and osteophyte formation—best characterize osteoarthritis. Inflammatory arthritis, like rheumatoid, usually shows symmetric joint space narrowing with erosions and periarticular bone loss, not this combination. Uniform cartilage loss is not the typical pattern for OA.