UC Davis

Study Design Retrospective chart review and review of literature. Objective Few case reports of traumatic L5-S1 displacement have been presented in the literature. Here we present two cases of traumatic spondylolisthesis showing both anterior and posterior displacement, the treatment algorithm, and a review of the literature. Methods The authors conducted a retrospective review of representative patients and a literature review of traumatic spondylolisthesis at the L5-S1 junction. Two representative patients were identified with traumatic spondylolisthesis: one with an anterior dissociation, and the other with a posterior dissociation. Results Radiographic, computed tomography, and magnetic resonance imaging illustrated the bony and soft tissue injury found in each patient, as well as the final stabilization and outcomes. Operative stabilization was necessary, and both patients were treated with open reduction internal fixation. The patient with posterior dissociation had complete recovery without neurologic sequelae. The patient with anterior dissociation had persistent bilateral L5-S1 radiculopathy with intact rectal tone, due to neurologic compression. Conclusions Few cases of traumatic spondylopelvic dissociation that are isolated to the L5-S1 disk space are described in the literature. We examined both an anterior and a posterior dissociation and treated both with L5-S1 posterior spinal fusion. The patient with anterior dissociation had persistent L5-S1 root injury; however, the patient with posterior dissociation had no neurologic deficits. This is the opposite of what is expected based on anatomy. These cases offer insight into the management of anterior and posterior L5-S1 spondylopelvic dissociation.