Traumatic posterior atlantooccipital dislocation combined with type II dens fracture and C1 anterior arch fracture: Two case reports

RATIONALE: Traumatic AOD is rare but highly associated with upper cervical spine injuries. We found no references in the literature of traumatic posterior atlantooccipital dislocation (AOD) combined with type II dens fracture (Anderson-D’Alonzo classification) and C1 anterior arch fracture. PATIENT CONCERNS: The first case was a 93-year-old male patient who was admitted to the Emergency Department complaining of incomplete quadriplegia after a fall from a height. The second was a 53-year-old male patient who visited the emergency department complaining of posterior neck pain following a high-speed motor vehicle collision. DIAGNOSIS: Reconstructed computed tomography (CT) scans clearly demonstrated posterior AOD combined with type II dens fracture and C1 anterior arch fracture. In addition, magnetic resonance imaging (MRI) also revealed type II transverse atlantal ligament injury (Dickman's classification) in the first patient. INTERVENTIONS: The patients chose not to undergo surgery; instead, they were immobilized with a rigid cervical brace. OUTCOMES: The patients were lost to follow-up. LESSONS: A thorough clinical evaluation and radiologic investigation (CT and MRI) on concomitant upper cervical injuries should be evaluated in traumatic AOD patients.