A 38-year-old man falls from a height and lands on his buttock. Radiographs show a vertical shear pelvic injury with a sacral fracture. CT demonstrates the fracture line passing through the right S1 and S2 neural foramina without extension into the spinal canal. According to the Denis classification, this is a:

• A Zone I sacral fracture
• B Zone II sacral fracture ✓
• C Zone III sacral fracture
• D Transalar sacral fracture

Explanation

The Denis classification divides the sacrum into three zones: zone I is the ala lateral to the foramina, zone II includes the neural foramina, and zone III is medial to the foramina including the central canal. A fracture traversing the S1-S2 foramina is therefore zone II, which carries the highest rate of neurological injury among the three zones. Transalar describes a fracture through the ala only, which would be zone I.

Reference: Rockwood and Green's Fractures in Adults, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.