Surgery for Locked Cervical Facets: A Technical Note

Cervical facet fractures and dislocations represent approximately 6% of all cervical spine fractures.1 The clinical spectrum of these injuries ranges from patient being neurologically intact to complete neurological deficits. They can be unilateral or bilateral and may be associated with subluxation or dislocations. The unilateral facet dislocations are produced because of flexion, hyperextension, lateral tilt, and rotation; while bilateral dislocations are due to flexion, axial loading, and anterior shear stress forces. The facets are subluxed when there is some contact between the two articular surfaces of the facet joint; while in dislocation, there is no residual contact (►Fig. 1A–D). The most common site of facet injuries is C5–C6 (25–60%), followed by C6–C7 (25–30%).2,3 This is because of the inherent anatomy of superior facets of the lower cervical spine, which are smaller with less height and more horizontal, as compared with the cranial facets. The majority (73%) of the bilateral facet dislocations are associated with facet fractures.4 The presence of midline cervical pain and tenderness with restriction of motion demands a thorough investigation. A large number of facet injuries (33%) can be missed at initial presentation.5 The majority (90%) of facet dislocations are associated with some degree of neurological compromise. The incidence of complete cord injury has been reported to be present in 16% in unilateral and 84% in bilateral dislocations.1,6 Allen et al have proposed a four-staged classification of lower cervical spine fractures, which includes facet subluxation, 25% translation of the cranial vertebral body with respect to the caudal body with unilateral locked facets, 50% translation with bilateral locked facets and complete dislocation.7