## Radiological Findings in Pott Disease ### Active Phase Characteristics **Key Point:** The active phase of Pott disease is characterized by **anterior vertebral body wedging, rarefaction (bone loss), and disc space involvement**, reflecting progressive destruction and inflammation. ### Classic Radiological Features by Phase | Feature | Active Phase | Healed Phase | |---------|--------------|-------------| | **Vertebral margins** | Ill-defined, rarefied | Sclerotic, well-defined | | **Disc space** | Narrowed, involved early | Preserved or partially involved | | **Vertebral shape** | Wedge-shaped (anterior collapse) | Flattened or sclerotic | | **Soft tissue** | Paravertebral abscess present | Fibrosis, minimal abscess | | **Bone density** | Decreased (rarefaction) | Increased (sclerosis) | ### Pathological Basis In the active phase, the tuberculous granulomas cause: 1. Bone destruction and necrosis → rarefaction on X-ray 2. Anterior vertebral body collapse → wedge deformity 3. Inflammatory edema → disc space narrowing 4. Caseous material → paravertebral soft tissue shadow **High-Yield:** The **disc space is involved early in TB** (unlike pyogenic infections where it is spared initially). This is a key distinguishing feature. **Clinical Pearl:** The **gibbus deformity** (sharp kyphosis) develops due to progressive anterior column collapse. Sclerotic margins indicate healing and transition to the healed phase. 
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