Atlantoaxial fusion and retrodental pannus in rheumatoid arthritis

Study Design. This study analyzed the influence of atlantoaxial fusion in rheumatoid arthritis patients on inflammatory retrodental pannus. Objectives. to determine the value of fusion on the magnitude of pannus as a compressive structure on the spinal cord. Summary of Background Data. Transverse and vertical instability may lead to neurologic deficits from spinal cord compression. Increased size of the retrodental pannus can exacerbate the neurologic deterioration. Anterior removal of dens and pannus followed by posterior fusion has been proposed in such situations as a method to relieve spinal cord compression. Methods. Twenty-two patients with atlantoaxial instability and verified pannus on magnetic resonance imaging underwent posterior fusion of the upper cervical spine. These patients were followed 12 to 75 months after surgery by clinical, radiologic, and magnetic resonance imaging evaluations. The size of the pannus was compared before and after surgery. Results. In all patients, the retrodental pannus had significantly decreased or disappeared postoperatively. Conclusions. Pannus reduction occurred even in patients whose disease was active or progressing, supporting the hypothesis that the pannus is more a reactive fibrous tissue resulting from instability rather than a direct consequence of the inflammatory process itself.