Clinical and pathologic correlations in traumatic spondylolisthesis of the axis.

Traumatic spondylolisthesis of the axis ("hangman's fracture") occurred in an 89-year-old man who died of unrelated causes. Postmortem examination of the cervical spine revealed a correlation between the anatomic lesion and clinical treatment and prognosis. Traumatic spondylolisthesis of the axis has a high potential for union because it usually occurs through the superior facet joint, in an area of well vascularized spongy cancellous bone. Fracture through the thin cortical bone of the pars interarticularis, conversely, is predisposed to the development of a nonunion and, hence, may explain this condition. While hyperextension with compression or distraction appears to have caused the injury in some cases, axial compression with flexion was the cause in this case.