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Vertical facet splitting: a special variant of rotary dislocations of the cervical spine.

A special variant of rotary displacement of the cervical spine with vertical splitting of an inferior articular process by its articulating partner is reviewed. Eighteen patients with unilaterally locked facet joints confirmed by computerized tomography were seen between 1986 and 1991. Five patients presented with vertical split fractures of an inferior articular process by impaction of the superior process of the subjacent vertebra. This specific fracture pattern is not accounted for in current classifications. Four males and one female with a mean age of 31 years (range 16 to 49 years) were affected. Three of the patients showed no neurological deficits. One patient presented with cerebral contusion and paresis of the right upper extremity, and in one patient the posterior funiculus was involved. Three of the injuries had been sustained recently; the other two were of longer duration. Surgical treatment was chosen in the three cases of recent injury. In two cases surgery was prompted by neurological deficits; in the third case impaction was felt to be of inadequate depth. Surgery consisted in fracture reduction and interbody fusion using plates. The two cases of long-term fractures were treated conservatively, and ankylosis of the facet joints eventually provided adequate stability. If radicular or spinal symptoms are absent, this special variant of locked facet joints can successfully be treated conservatively leaving the rotary displacement uncorrected, provided impaction is adequately deep. The author's experience has shown that indications for surgical management are relative rather than absolute in this fracture variant and that use of computerized tomography is essential to establish the fracture pattern.