American Board of Internal Medicine (ABIM) Certification Practice Exam

What are the radiographic hallmarks of osteoarthritis?

1. Joint-space narrowing and subchondral sclerosis

2. Periarticular osteopenia and marginal erosions

3. Fractures and cystic lesions

4. Soft tissue swelling and joint effusion

The correct answer is: Joint-space narrowing and subchondral sclerosis

The radiographic hallmarks of osteoarthritis primarily include joint-space narrowing and subchondral sclerosis. Joint-space narrowing occurs as a result of cartilage loss, which is a key feature of osteoarthritis. As the cartilage deteriorates over time, the distance between the bones in the joint decreases, leading to a visible reduction in the joint space on radiographs. Subchondral sclerosis refers to the increased density of bone just below the cartilage surface in weight-bearing joints. This occurs due to increased stress on the underlying bone as the protective cartilage wears away. The body responds to this stress by thickening and strengthening the bone in an attempt to compensate for the loss of cartilage, which is indicative of osteoarthritis. These two features—joint-space narrowing and subchondral sclerosis—are critical in diagnosing osteoarthritis on imaging studies. Other choices represent features typically associated with different conditions. For example, periarticular osteopenia and marginal erosions are often seen in inflammatory arthritides, such as rheumatoid arthritis. Fractures and cystic lesions may be associated with various bone pathologies but are not specific for osteoarthritis. Finally, soft tissue swelling and joint effusion are not specific to osteoarthritis and can occur in many other joint conditions,