Atlanto-axial subluxation in rheumatoid arthritis. A study of 104 hospital patients.

Arthritic affection of the upper cervical spine is relatively common in rheumatoid arthritis (RA). Atlanto-axial subluxations are also reported to occur frequently, but it seems that neurological symptoms due to the subluxations seldom occur. We have studied 104 consecutive in-patients. In a group of 50 non-arthritics we have measured the distance from dens to the anterior arch of the atlas, and from dens to the foramen magnum line. By means of percentile-estimate we have defined values at risk for having pathological values for the measured distances. In 104 rheumatoid arthritis patients we found that 45% of the patients had values at risk, but only one of the patients had medullary neurological signs. A planned follow-up study will show if oncoming neurological symptoms due to subluxations will occur in the risk-group or in the group now defined as having normal values.