[Ossification of the Transverse Ligament of the Atlas on CT: Frequency and Associated Findings].

Purpose: To determine the frequency of ossification of the transverse ligament of the atlas (OTLA) and to investigate the associated findings on cervical spine CT and plain radiography.

Materials And Methods: We reviewed 5201 CT scans of the cervical spine of 3975 consecutive patients over an 11-year period for the presence of OTLA and compared them with those of age- and sex-matched controls. The frequency and associated findings of OTLA were investigated and statistically correlated.

Results: The overall frequency of OTLA was 1.1% (45 of 3975 patients) and increased with age ( < 0.005). The frequency of OTLA in patients over 80 years was 12%. The space available for the spinal cord (SAC) was smaller in patients with OTLA ( < 0.005). Mineralization of the complex of the anterior atlantooccipital membrane and Barkow ligament, ossification of the ligamentum flavum, and kyphosis of the cervical spine positively correlated to the presence of OTLA ( < 0.005).

Conclusion: OTLA was associated with age, SAC narrowing, cervical kyphosis, and ossification of other cervical ligaments and may be associated with degenerative spondylosis, systemic hyperostotic status, or mechanical stress or instability.