Traumatic dislocation of the lumbosacral junction diagnosis, anatomical classification and surgical strategy.

PURPOSE OF THE STUDY: Traumatic lumbosacral dislocation is a rare lesion often characterised by a fracture dislocation of L5-S1 articular facets associated with anterior L5 slipping. Because of its rarity, the surgical strategy of lumbosacral traumatic dislocation remains controversial. We report the most important series of traumatic lumbosacral dislocation. The cases of six men and five women are presented. We discuss the diagnosis and surgical treatment options regarding the different type of lesions. A moderate anterior slipping of L5 over S1 was present in eight cases. The lesion was a bilateral lumbosacral fracture dislocation in eight cases, a pure lateral dislocation in two cases and a unilateral rotatory dislocation in one case. Patients were multiple-trauma patients in eight cases. A radicular deficit was present in two cases. All patients were treated surgically with a posterior osteosynthesis and fusion. A circumferential fusion was made in six cases. In four cases, the anterior fusion was made during the posterior approach. The postoperative course was favorable in all the cases. One patient necessitated secondarily an iterative posterior lumbosacral fixation and anterior fibular bone graft because of a lumbosacral pseudarthrosis. Traumatic dislocation of the lumbosacral junction is a rare and severe spinal fracture which occurs in patients after high energy trauma and could be initially misdiagnosed. We devised a new classification based on anatomical lesions. Treatment is always surgical, requiring reduction, osteosynthesis, and fusion. In case of L5 anterior slipping, it is crucial to assess the L5S1 disc by MRI or surgical exploration for disc disruption. In such case, we recommend to perform circumferential fusion to prevent lumbosacral pseudarthrodesis.