Ossification of Posterior Longitudinal Ligament in Cervical Spine and Its Association With Ossified Lesions in the Whole Spine: A Cross-Sectional Study of 2500 CT Scans.

STUDY DESIGN

A retrospective study.

OBJECTIVE

To identify the prevalence and characteristics of ossified posterior longitudinal ligament (OPLL) in the cervical spine and its association with other spinal ligament ossifications.

METHOD

This study is a retrospective review of whole spine CT scans of polytrauma patients from 2009 to 2018. Patients were screened for cervical OPLL (C-OPLL), thoracolumbar OPLL, thoracic ossified ligamentum flavum (OLF), cervical and thoracolumbar ossified anterior longitudinal ligament (C-OALL AND T-L OALL), ossified nuchal ligament (ONL) and, diffuse idiopathic skeletal hyperostosis (DISH) using CT scans. Their prevalence and distributions were assessed using statistical tools. Chi-square tests were used to determine statistical association between the categorical parameters.

RESULTS

Out of 2500 patients, 128 had C-OPLL with a prevalence rate of 5.12% with mean age of 55.89 year. The most commonly affected level was C5, followed by C6, and C4. The segmental OPLL was highest in number (77.7%), followed by localized type (14.8%). While the prevalence rate of thoracic OPLL was 0.56%, OLF was 9.9%. Ossifications that coexisted along with C-OPLL were thoracic OPLL (7.81%), thoracic OLF (36.71%), cervical OALL (29.68%), thoracolumbar OALL (37.5%), DISH (27.34%) and, ONL (7.03%).

CONCLUSION

Our study indicated a prevalence rate of 5.12% for C-OPLL with a predominance of segmental OPLL (77.7%). Among these patients, approximately 36% had coexisting thoracic OLF. In patients with symptomatic OPLL induced cervical myelopathy, MRI analysis of whole spine with relevant CT correlation may help in detecting additional ossification sites of compression.