Cervical vertebral injuries associated with the ossification of the posterior longitudinal ligament: Imaging features

BACKGROUND Spinal injuries associated with ossification of the posterior longitudinal ligament (OPLL) have been characterized. However, the imaging features of traumatic cervical spine fractures in patients with OPLL have not been assessed adequately. PURPOSE To characterize the patterns of traumatic cervical spine fractures associated with different types of OPLL. MATERIAL AND METHODS We retrospectively analyzed the patterns of fractures resulting from cervical spine injury in patients with OPLL of different types and assessed the fracture patterns in patients with ankylosed segments. RESULTS Twenty-six patients (23 men, 3 women; median age, 67.0 years; age range, 43-87 years) were included. Fall from a height <3 m was the most common trauma. Contiguous type OPLL was seen in 11 patients (42%), segmental type in 11 (42%), and mixed type in four (15%). Four of the contiguous OPLL and one of the mixed OPLL patients had ankylosed segments. The incidence of cervical fractures was 69% (16/26): seven (64%) in contiguous OPLL, five (46%) in segmental OPLL, and in all four patients with mixed OPLL. Unilateral interfacetal fracture-dislocation was most common (4/16); the others were bilateral interfacetal fracture-dislocation, fractures through the ankylosed segment, transdiscal fractures, isolated facet fractures, and compression fractures. Cervical fractures were exclusively observed in the C4 to C7, except in one case occurred at the C2 level. CONCLUSION Interfacetal fracture-dislocation in the lower cervical vertebrae constitutes the most common injury resulting from minor trauma.