American Board of Internal Medicine (ABIM) Certification Practice Exam

What is one of the features of osteoarthritis visible on X-rays?

1. Joint effusion

2. Marginal osteophyte formation

3. Subcutaneous nodules

4. Synovial thickening

The correct answer is: Marginal osteophyte formation

One notable feature of osteoarthritis visible on X-rays is marginal osteophyte formation. Osteophytes, or bone spurs, are bony projections that develop along the edges of a joint, often as a result of the degeneration of cartilage and bone associated with osteoarthritis. These formations occur due to the body's attempt to repair itself in response to joint instability or increased load on the bone. In osteoarthritis, as the joint cartilage deteriorates, mechanical stress on the bone can trigger the production of osteophytes at the joint margins. This process is a key x-ray finding in diagnosing osteoarthritis because the presence of osteophytes is indicative of chronic joint disease. It helps differentiate osteoarthritis from other types of arthritis that may not show this characteristic. In contrast, joint effusion typically involves the presence of excess fluid in the joint space, which may not be directly observable on a standard X-ray. Subcutaneous nodules, often seen in conditions like rheumatoid arthritis, are not features of osteoarthritis. Similarly, synovial thickening, often associated with inflammatory arthritides, is not a typical finding in osteoarthritis and is better visualized through ultrasound or MRI rather than plain X-rays.