Posterior stabilization of the cervical spine in rheumatoid arthritis: clinical results and magnetic resonance imaging correlation.

Thirteen patients with atlantoaxial dislocation(s) had posterior stabilization and were evaluated clinically with magnetic resonance (MR) imaging and conventional radiography both pre- and postoperatively. Cases with anterior instability had large periodontoid granulomatous pannus formation, but this was lacking in cases with fixed cranial settling. The pannus caused cord compression in four cases and occupied the entire anterior subarachnoid space in four other cases. After stabilization, the granuloma decreased in size in all patients and in four cases it vanished completely. Major signs of myelopathy corresponded to cord compression at MR imaging. Minor possible signs of neural deficit were found in seven cases and their importance was not clearly understood before surgery, but because all preoperative symptoms disappeared, it was necessary to check for even obscure signs as early warnings of a threatening myelopathy.