Radiographic measurements of occipito-atlanto-axial dislocation in rheumatoid arthritis.

Atlanto-axial dislocation is frequently found in patients with rheumatoid arthritis. Vertical atlanto-axial dislocation with invagination of the dens into the foramen magnum may result in most serious myelopathy. Decompression, removal of the dens and atlanto-axial fixation have given fair results in such cases. It is our aim, however, to prevent myelopathy in our rheumatoid patients. The prerequisite for that is routine, radiographic examination of the cervical spine and prophylactic atlanto-axial fixation. For these routine controls we need a radiographic measuring method which can be used even in cases of greater destruction. Our radiographic measuring method is compared with other methods and seems to be more appropriate and also gives information about the forward or backward tilting of the atlas. In a group of non-rheumatoid patients we have measured normal figures for this method.