Complete fracture-dislocation of the atlantoaxial complex: case report and recommendations for a new classification of dens fractures.

A 77-year-old man fell and sustained a fracture-dislocation of the atlantoaxial complex with 20 mm of posterior displacement. Initial and repeat examinations failed to diagnose the fracture-dislocation, which was first diagnosed by a magnetic resonance imaging study 16 weeks after the injury and after the patient had developed a profound myelopathy. The patient was treated by a C2 decompressive laminectomy and an in situ posterior fusion with iliac bone graft and internal fixation with gradual resolution of his myelopathy. Postoperatively he developed respiratory problems and persistent difficulties swallowing, believed to be at least partly due to cranial nerve involvement. A new classification system for dens fractures is suggested.