What are the three radiographic hallmarks of Osteoarthritis in an X-ray?

• A. Osteophytes, Subchondral cysts, Joint space narrowing
• B. Osteophytes, Subchondral sclerosis, Joint effusion
• C. Osteopenia, Soft tissue edema, Calcific tendinopathy
• D. Subchondral cysts, Periarticular osteolysis, Erosion of the cortex

Answer: (A)

Osteoarthritis on plain X-ray most visibly reflects changes in both the cartilage and the bone beneath it. The three hallmarks you’ll frequently see are osteophyte formation at joint margins, narrowing of the joint space from cartilage loss, and changes in the subchondral bone such as cyst formation.

Osteophytes are bony outgrowths that develop as the joint tries to stabilize itself in response to cartilage deterioration and joint instability. Joint space narrowing directly indicates loss of articular cartilage, which reduces the gap between the bones. Subchondral cysts form in the bone under the cartilage due to altered loading and fluid pressure, often resulting from microfractures and synovial fluid intrusion into the subchondral bone.

While subchondral sclerosis and other bone changes can also appear in OA, the combination of osteophytes, joint space narrowing, and subchondral cysts is a classic, characteristic radiographic pattern. Joint effusion and soft tissue edema, on the other hand, are better assessed with ultrasound or MRI and are not primary radiographic hallmarks of OA.