Complications in three-column cervical spine injuries requiring anterior-posterior stabilization.

A study was undertaken to elicit the hidden factors that, when identified, would signal the presence of cervical spine instability. Data were derived from the records and radiographs of 21 patients having sustained traumatic injury to the lower cervical spine (C3-C7) and who failed a single-stage posterior stabilization procedure necessitating a second (or combined) anterior-posterior arthrodesis. Mechanism of injury most frequently identified in this group was the distraction-flexion (locked facets) pattern (nine patients) and the "tear drop" compression-flexion injury pattern (seven patients). All 21 patients underwent a posterior wiring and bone graft stabilization procedure with persistent postoperative instability. Thus, failure to recognize the presence of "three-column" instability, the sine qua non of this group, resulted in the failure of posterior tension band stabilization as a means of gaining cervical spine stability. Three-column cervical spine instability is suspected in the presence of: 1) retrolisthesis and angulation of the superior vertebra on the next inferior vertebra; 2) distraction of the posterior interspinous ligaments sufficient to allow subluxation or dislocation of the facets; in conjunction with 3) a "shear" dislocation of one vertebra on another. Anterior shearing force through the disc space is capable of disrupting the intervertebral disc, along with disruption of the anterior and posterior longitudinal ligaments, each contributing to the presence of anterior and middle column cervical spine instability.