Abstract

The commonly accepted mechanism of rheumatoid C₁—C₂ dislocation is the incompetence of the transverse ligament of C₁ vertebra. The presence of rheumatoid granulation tissue between the anterior arch of C₁ vertebra and the odontoid process is an important factor. This might explain why the dislocation becomes irreducible when the disease progresses. In a 55 year old man, transoral removal of the rheumatoid granulation tissue made the previously irreducible C₁—C₂ dislocation reducible. Stabilization of the reduced C₁—C₂ articulation was accomplished at a second operation by posterior fusion of the occiput to C₁, C₂, and C₃ vertebrae.