Sagittally oriented fractures of the lateral masses of the cervical vertebrae.

Lateral flexion of the cervical spine may cause a sagittally oriented fracture of the lateral mass with shearing of all or part of the lateral mass away from the vertebral body. We report 22 patients with 24 sagittal fractures of the cervical lateral masses. Cross-table lateral roentgenograms suggested the presence of a sagittal lateral mass fracture in two thirds of the cases based upon malalignment or widening of the facet joints, displaced fracture fragments, subluxation of the spine, or rotation of the spine above the level of abnormality. However, the cross-table lateral roentgenogram was normal in one third of cases. Oblique roentgenograms were available in eight cases; these were positive in five, equivocal in one, and negative in two. Visible fracture lines, often associated with lateral displacement of part or all of the lateral mass, allowed all 24 fractures to be detected on the supine anteroposterior view films. Sagittal lateral mass fractures were unstable in 59% (13/22) of the cases; neurologic deficits, including quadriplegia, hemiplegia, and radiculopathy, were present in 45% (10/22). Computed tomography and complex-motion tomography were useful in confirming the sagittal lateral mass fracture and in detecting other associated fractures.