TRANSARTICULAR SCREW FIXATION OF ATLAS AN D AXIS IN RHEUMATOID-ARTHRITIS

In 45 patients (34 female, 11 male) suffering from rheumatoid arthriti s, a transarticular screw fixation was performed to establish stabilit y between atlas and axis. Mean age was 57 (ranging from 31-79 years). Mean history of rheumatoid arthritis was 17 years (3-42 years) before surgery was indicated. The ventral atlantoaxial interval was 11 mm on average. In all patients the joints between atlas and axis were affect ed only, there being no single case of destruction of the occipito-atl antal joints. There was no invagination of the dens into the posterior cranial fossa. In 17 cases neurological deficits were detected (Ranaw at classes II and III). Surgical technique has been thoroughly describ ed. For the first 16 operations, 2.2 mm double-threaded screws were us ed, whereafter 3.5 mm cortical screws were inserted. Autologous bone w as placed on the laminae of the atlas and the axis in 37 patients, 21 of which received additional fixation of the bone by means of a cable- cerclage. In 2 operations methylmethacrylate was applied as a spacer b etween the dorsal arch of the atlas and the spinous process of the axi s. Screws alone were inserted in 6 cases. No intraoperative complicati ons were observed. Injuries to the vertebral artery or the dura mater did not occur. Mean follow up in 43 of 45 patients was 28 months (6-62 months). Two pseudarthrosis were observed in patients without additio nal bone graft. In patients with bone grafting, one pseudarthrosis onl y occured as a result of a misplacement of one screw. As long as exact placement of the screws (described in detail) was achieved and bone g rafting was applied no pseudarthrosis was observed in 35 cases. There were two cases of screw breakage with 2.2 mm screws, but none with 3.5 mm screws. Revision surgery was not necessary in any of the cases. A preoperative CT-scan is mandatory to establish any abnormal courses of the vertebral arteries (described in the literature), which is a cont raindication for this technique, whereas age need not be considered. I n contrast to previous techniques, transarticular screw fixation is po ssible in cases with a split or a missing dorsal arch of the atlas. Th is technique should be considered, because of its low complication rat e, even in cases with increasing instability without neurological defi cits, to ease the burden of the patient knowing that a transverse synd rome may result in cases of untreated instability.