Contiguous-Level Unilateral Cervical Spine Facet Dislocation—A Report of a Less Discussed Subtype

Abstract

Unilateral facet dislocation of subaxial cervical spine trauma is characterized by dislocation of inferior facet of superior vertebra over the superior facet of inferior vertebra. The injury is due to high-velocity trauma and associated with instability of spinal column. Such unilateral facet dislocations occurring at multiple adjacent levels for some reason are not reported or studied frequently. We have reported two cases of multiple-level dislocation of unilateral facets managed in our hospital with a review of available literature. The injury occurs as one side of the motion segment translates and rotates around an intact facet on the contralateral side. The major mechanism of injury is distractive flexion injury with axial rotation component. The injury is associated with instability secondary to loss of the discoligamentous complex. In cases with multiple-level dislocations of unilateral cervical facets, there are multiple mechanisms associated with significant neurological injury and most of them succumb at the site of injury. Only three other cases are available in English language literature. The neurological outcome is invariably poor. Multiple-level facet dislocations of subaxial cervical spine are reported sparsely in literature. We suspect that due to high-velocity nature of these injuries, most of them succumb soon after injury and not often reported. This article reports two cases of contiguous-level unilateral facet dislocation of subaxial cervical spine with associated injuries and the outcomes with review of literature.

Commentary on “Contiguous-Level Unilateral Cervical Spine Facet Dislocation—A Report of a Less Discussed Subtype”

“…16 Combined anterior and posterior approaches offer greatest biomechanical stability 16,21,22 and are particularly suitable if there is extensive ligamentous damage (as seen in bilateral facet dislocations) or when accompanied by corpectomies for vertebral body fractures 21,22 as happened in these cases too. 3 The take-home points from this study 3 would thus be:…”

“…The corollary we can draw from this is that not only is operative intervention mandatory in UFD, one must also look carefully for signs of covert adjacent segment injury like undisplaced facet fractures (which may be a milder form of the contiguous UFD described by Das et al 3 ) and if found would mandate inclusion of more levels in the fixation.…”

“…The American Academy of Neurological Surgeons in a consensus statement declared that “there was insufficient evidence to support either treatment standards or treatment guidelines in regards to reduction of UFDs.” 10 12 They noted the risk of permanent neurological complications after closed reduction in awake patients was approximately 1%, while transient injury occurred in 2 to 4%. 12 They have also cautioned against closed reduction in patients with an additional injury (as in the cases described by Das et al 3 ) and in those who are obtunded. 10…”

“…In our country, most surgeons would then go on to reduce the involved level, decompress neural elements, and fix the spine based on these radiological investigations alone. In this context, I read with interest the article by Das et al 3 where they have described contiguous-level UFDs as a subtype of the larger spectrum of UFDs since the optimal treatment for these injuries has several areas of dispute. 1 Is There a Role for Conservative Treatment (Only Closed Reduction Followed by Immobilization) in UFDs?…”