American Board of Internal Medicine (ABIM) Certification Practice Exam

What is a distinguishing radiographic feature of rheumatoid arthritis compared to osteoarthritis?

1. Marginal osteophyte formation

2. Subchondral sclerosis

3. Periarticular osteopenia

4. Joint-space widening

The correct answer is: Periarticular osteopenia

Rheumatoid arthritis (RA) and osteoarthritis (OA) have distinct radiographic features that help differentiate between the two conditions. One key feature of RA is periarticular osteopenia, which refers to a reduction in bone density that occurs around the affected joints. This is particularly significant in inflammatory arthritides like RA, where the disease process leads to inflammation and synovitis, resulting in erosive changes and localized damage to the bone. In timing and location, periarticular osteopenia often precedes joint erosion and represents the destructive nature of rheumatoid arthritis. In contrast, osteoarthritis typically does not exhibit this feature prominently; instead, OA is characterized by marginal osteophyte formation, subchondral sclerosis, and joint-space narrowing due to cartilage wear, but not by periarticular bone loss. Recognizing periarticular osteopenia can provide clinicians with critical insights into a patient's diagnosis and aid in distinguishing rheumatoid arthritis from osteoarthritis, helping guide appropriate treatment strategies early in the disease process.