What are the three hallmarks of osteoarthritis seen on X-ray?

The three hallmarks of osteoarthritis that are typically observed on X-ray are subchondral cysts, joint space narrowing, and osteophytes.

Subchondral cysts appear as fluid-filled sacs that develop beneath the cartilage surface, indicating an alteration in the bone due to the degenerative process of osteoarthritis. Joint space narrowing signifies a loss of cartilage, which is a fundamental change in osteoarthritis as the cushioning effect of cartilage decreases, leading to bones coming closer together. Osteophytes, or bone spurs, are bony projections that form along joint margins as the body attempts to increase the contact area and stabilize the joint in response to the degenerative changes.

Together, these features help illustrate the typical pathological transformations associated with osteoarthritis, providing important diagnostic criteria for clinicians when assessing joint health and addressing potential treatments.