A 19-year-old diver strikes the top of his head on the pool bottom. Open-mouth odontoid radiograph shows symmetric lateral displacement of both C1 lateral masses away from the dens, and the combined displacement exceeds 7 mm. What does this finding indicate?
- A Rupture of the transverse atlantal ligament ✓
- B Isolated anterior arch fracture of C1
- C Type III odontoid fracture
- D Atlantoaxial rotatory subluxation
Correct answer: A. Rupture of the transverse atlantal ligament
Explanation
This is a Jefferson burst fracture of the atlas from axial load. By the rule of Spence, combined lateral displacement of the C1 lateral masses over 7 mm implies the transverse atlantal ligament has ruptured, making the injury unstable and mandating surgical stabilisation rather than simple collar immobilisation. Rotatory subluxation presents with a cock-robin tilt and asymmetric facet positions, not symmetric lateral mass displacement.
Reference: Bailey and Love's Short Practice of Surgery, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.