Bamboo spine is pathognomonic for which condition?

• A. Rheumatoid arthritis
• B. Gout
• C. Psoriatic arthritis
• D. Ankylosing spondylitis

Answer: (D)

Bamboo spine reflects fusion and calcification along the spine from chronic inflammatory changes in ankylosing spondylitis. In this condition, repeated inflammation at the spine’s entheses leads to new bone formation that bridges the vertebrae with vertical syndesmophytes, eventually fusing the spine and giving it a bamboo-like appearance on radiographs. This radiographic pattern is highly characteristic of ankylosing spondylitis, making it the most specific clue among the options. Other conditions listed can affect the spine but do not produce this classic full-spine fusion pattern; rheumatoid arthritis tends to involve peripheral and cervical joints with erosions, gout presents with tophi and joint inflammation, and psoriatic arthritis can involve the spine without the distinctive bamboo-like fusion.