Traumatic rotatory displacement of the lower cervical spine

Traumatic rotatory displacement (TRD) are defined as all slight anterior corporeal displacements (less than 1/3 of the vertebral body) secondary to different vectors, but with a constant and dominant rotatory component. The authors report on 47 cases of TRD (35% of all severe lower cervical spine injuries) (follow-up: 6 months to 7 years). TRD occurs only when two lesions are present: an anterior lesion in the disk and ligaments, and a posterior lesion of the articular process, as the authors confirmed earlier in an experimental study on monkeys and specimens. Depending on the nature of the posterior lesions, three anatomoclinical types occur: 1) posterior capsular lesions cause unilateral facet dislocation (UFD): ten cases; 2) bony lesions of the articular process cause unilateral facet fracture (UFF): 28 cases; 3) double bony lesions, which can set free the articular facets, are called fracture separation of the articular pillar (FSAP): nine cases. The common radiographic characteristic of these three lesions is slight anterior displacement (or antero-listhesis), which is well seen on the lateral film; only tomograms or CT scans can show the posterior lesions. Instability, as defined by Roy-Camille, Denis and our experiments, was obvious on X-rays: soon after the injury, for UFD, and some time later, for 18 UFF and three FSAP. Statistically, 25% of all cases of TRD are associated with another traumatic lesion of the lower or upper cervical spine. Clinically, there is a 30% rate of radicular complications in TRD: this figure is higher than that of other injury types.