Diagnostic accuracy of cervical spine imaging to predict thoracic ossification of the posterior longitudinal ligament: Retrospective chart review

Purpose: To analyze the significance of ossification index of cervical posterior longitudinal ligament as a risk factor for thoracic OPLL (ossification of the posterior longitudinal ligament) in patients with cervical OPLL. Methods: We retrospectively analyzed the clinical data of cervical OPLL patients in Changzheng hospital, who received chest CT scans for screening of COVID-19, and included 87 patients into this study. According to the radiographic evidence, 87 patients were divided into CT group(cervical OPLL combined with thoracic OPLL) and C group(cervical OPLL group). We measured the cervical OS index (ossification index), and analyzed the relationship between thoracic OPLL and cervical OS index. Results: There was no difference of age?sex?duration of symptoms?comorbidity between the 2 groups(P > 0.05). The mean cervical OS index was higher in the CT group than in the C group (8 +/- 2 VS 3 +/- 2,P < 0.001). Conclusions: Patients with cervical OS index > 8 was considered as "high risk " of tandem OPLL, while with value <= 4 was considered as "low risk ". Index between 5 and 8 were considered as "middle risk ". This study demonstrated that the cervical OS index may be used as an indicator of thoracic OPLL in patients with cervical OPLL, with a high diagnostic accuracy.