Region II: C1 ring and C1–C2 joint - Type B: Nondisplaced ligamentous injury

Type B injuries are transverse atlantal ligament insufficiencies, which may or may not be associated with fractures. There is no sign of C1–C2 displacement.

If a stress test shows displacement, then it is a Type C injury.

Treatment may be surgical or with halo vest in case there is bony avulsion injury.

Region II Type B: Non-displaced ligamentous injury of C1 and the C1–C2 joint

Displaced fractures with widening greater than 7 mm (rule of Spence: overhang on open-mouth odontoid view) suggest injury of the transverse atlantal ligament.

$Displaced fractures with widening greater than 7 mm suggest injury of the transverse atlantal ligament.$