On an oblique X-ray for AS, what is typically seen?

• A. Sclerosis on the SI joints
• B. Syndesmophytes
• C. Bone edema
• D. Bamboo spine

Answer: (B)

In ankylosing spondylitis, chronic inflammation of the spine leads to new bone formation along the ligaments surrounding the vertebrae. The radiographic hallmark on spine films is the appearance of syndesmophytes—marginal, bridging bony growths that connect adjacent vertebral bodies. On oblique views these bridging ossifications are often clearly visible and represent the classic sign of AS on X-ray. As the disease advances, these syndesmophytes can fuse segments of the spine, producing a bamboo-like appearance, but that is a late finding. Other options reflect different contexts (sacroiliac joint sclerosis seen on pelvic films, bone edema seen on MRI, bamboo spine due to advanced fusion) rather than the typical early spinal change seen on an oblique view. Syndesmophytes are the feature that best fits the question.