title: Vacuum phenomenon as a sign of an ununited, unstable dens fracture.
mesh_terms: D001368:Axis, Cervical Vertebra / Q000293:injuries*; D005599:Fractures, Ununited / Q000000981:diagnostic imaging*; D005740:Gases; D006801:Humans; D008297:Male; D008875:Middle Aged; D009809:Odontoid Process / Q000293:injuries*; D014057:Tomography, X-Ray Computed; D014618:Vacuum
chemical_list: D005740:Gases