RESUMEN
A rare case of atlantoaxial lateral mass joint interlocking secondary to traumatic posterolateral C1,2 complete dislocation associated with type II odontoid fracture is herein reported and the impact of atlantoaxial joint interlocking on fracture reduction discussed. A 72-year-old man presented with traumatic atlantoaxial lateral mass joint interlocking without spinal cord signal change, the diagnosis being confirmed by radiography and 3-D reconstruction digital anatomy. Posterior internal fixation was performed after failure to achieve closed reduction by skull traction. After many surgical attempts at setting had failed because of interlocking of the lateral mass joints, reduction was achieved by compressing the posterior parts of the atlantal and axial screws. Odontoid bone union and C1,2 posterior bone graft fusion were eventually obtained by the 12-month follow-up. The patient had a complete neurological recovery with no residual neck pain or radiculopathy.