Management of fracture separations of the articular mass using posterior cervical plating.

Fracture separations of the articular mass are a specific group of unilateral facet fractures that must be considered separately because of their unique two-level instability. This fracture pattern involves a longitudinal fracture of the lamina and a fracture of the pedicle on the same side of the spine at the same level. It is characterized roentgenographically by horizontalization of the lateral mass, with a mean translation of 4.6 mm and a mean angulation of 6.9 degrees. In this study the deformity most commonly occurs at the level below the fracture (19 patients) but also occurred at the level above (5 patients). There is a high incidence of neurologic involvement (14 of 24 patients), most often radicular in nature. This injury results in two level instability requiring a three-level, two-interspace stabilization. All twenty-four patients in this series underwent posterior cervical plating with either an asymmetric (8), symmetric (9) or porte manteau (7) construct. Statistically significantly better results (P < 0.05) were achieved with either a symmetric or porte manteau construct. Complications including neurologic deficit and loss of correction were more frequent in the asymmetric group.