Open-mouth odontoid view radiograph of a 40-year-old man after a diving accident shows bilateral outward displacement of the lateral masses of C1 relative to the C2 articular pillars. What does this finding indicate?
- A Hangman's fracture of C2
- B Type II odontoid fracture
- C Jefferson fracture of C1 ✓
- D Atlantoaxial rotatory subluxation
Correct answer: C. Jefferson fracture of C1
Explanation
Bilateral lateral displacement of the B1 lateral masses on the open-mouth view indicates a Jefferson fracture, a burst fracture of the B1 ring produced by axial loading. Displacement occurs because the ring fails at its anterior and posterior arches. Hangman's fracture is traumatic spondylolisthesis of the B2 pars, seen on the lateral film, and type II odontoid fracture shows a lucency through the base of the dens. Rotatory subluxation causes asymmetric position without bilateral mass displacement.
Reference: Bailey and Love's Short Practice of Surgery, 28th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.