Vertical settling in rheumatoid arthritis. Diagnostic value of the Ranawat and Redlund-Johnell methods.

The usefulness of the recently developed Ranawat and Redlund-Johnell craniometric methods was compared with that of the conventional McGregor method for diagnosing vertical settling (VS) of the skull and the atlas on the axis in 209 patients with rheumatoid arthritis (RA). Statistical analysis of the values obtained from roentgenograms revealed close correlations among the three methods. The first two methods were superior to the McGregor method because the measuring points could be identified on plain roentgenograms of the cervical spine in virtually all cases. The McGregor value could not be determined in 38 (18%) patients. Since medullary compression could be detected by magnetic resonance imaging in all patients who showed abnormal Redlund-Johnell values, the Redlund-Johnell method may be useful for diagnosing advanced VS. It also detects not only atlantoaxial lesions but also atlantooccipital lesions. Thus, the Redlund-Johnell method appears to be the best method for diagnosing VS in RA patients.