[Vertical fracture of the odontoid process. A case report].

Odontoid process fractures are commonly classified as types I through III according to the Anderson & D'Alonzo scheme. A fourth type of fracture not included in this classification has been described as "vertical odontoid fracture". These fractures are located in the vertical plan of the dens. We describe a new case of an oblique coronally oriented fracture through the odontoid process with extension to the body of C2. Our patient is a 22-year-old lady who sustained a road traffic accident with head, facial and cervical trauma. Computed tomography with 2D and 3D reconstruction characterized the fracture. We suppose that the mechanism of injury was an axial load associated with dorsal to ventral force. The patient was placed on a halo-vest for 12 weeks with good healing and no evidence of instability on flexion-extension studies 6 months later. This case demonstrates that the odontoid and C2 vertebral body fractures belong to the same spectrum and are determined by the patient's anatomy and the mechanism of the injury.