Atlantoodontoid osteoarthritis: comparison of lateral cervical projection and CT.

The purpose of this study was to assess the accuracy of lateral cervical spine radiography in the detection of degenerative atlantoodontoid (AO) osteoarthritis, with CT as gold standard. In 50 patients, lateral radiographs and CT of the AO joint were blindly and independently graded by two radiologists: 0 = normal, 1 = mild degenerative disease, 2 = severe degenerative disease. Radiography was most accurate in distinguishing absent or mild disease from severe disease (83% sensitivity, 84% specificity). Sensitivity in distinguishing absent disease from mild or severe disease was 87%. Specificity, however, was low (52%), due to overestimation of the degenerative involvement on radiography. It is concluded that conventional radiography is a useful technique in screening for AO osteoarthritis, especially in severely degenerated joints. However, CT provides the best radiographic detail necessary for accurate diagnosis.