A 35-year-old presents with low-grade fever and lower back pain for 6 months. MRI shows vertebral end-plate erosion, disc space narrowing, and anterior epidural granulation tissue at L1-L2 with a psoas abscess. This is Pott's spine. Which radiological feature distinguishes spinal TB from pyogenic spondylodiscitis?

• A Disc space preserved until late in TB; early disc destruction in pyogenic infection ✓
• B Anterior column destruction with kyphosis is specific for pyogenic infection
• C Skip lesions involving multiple non-contiguous levels are more common in pyogenic infection
• D Psoas abscess occurs only in pyogenic spondylodiscitis

Explanation

In spinal TB, Mycobacterium tuberculosis spreads through end-plate vessels and destroys vertebral bodies while the avascular disc is initially spared — the disc narrows only after adjacent vertebral collapse. Pyogenic organisms produce proteolytic enzymes (hyaluronidase, proteases) that destroy the disc early and prominently. Skip lesions (multi-level non-contiguous involvement), large paravertebral abscess with calcification, and sub-ligamentous spread under the anterior longitudinal ligament are features of TB. Psoas abscess occurs in both but is far more common in TB.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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