Traumatic lumbosacral dislocation: four cases and review of literature.

Diagnosis, physiopathology, and treatments of four patients with traumatic lumbosacral dislocations are described. This is a rare but severe lesion of the lumbosacral junction that usually occurs in patients with multiple trauma. It often is not thought of and the diagnosis may be missed. Evidence of lumbosacral dislocation should be examined and confirmed by computed tomography scans in patients with multiple fractures of transverse lumbar processes, asymmetric lumbosacral joints on frontal images, or slipping of L5 over S1 on lateral images. Treatment consists of reduction of the dislocated and fractured parts, lumbosacral arthrodesis, a posterolateral graft, and posterior instrumentation. Instrumentation may be short, extending from L5 to S1, or long, from L4 to S1, depending on the extension of the lesion. In some cases, reduction can be done intraoperatively, when the L4-S1 instrumentation is inserted, provided L5 transpedicle screws are pulled posteriorly. It usually is preferable to explore the vertebral canal to ensure that there is no disc lesion compressing the dura before proceeding with reduction. Compression of the dura could be avoided with a preoperative magnetic resonance imaging scan on which a lesion of the L5-S1 disc is sought. Additional interbody vertebral arthrodesis should be considered when the L5-S1 disc is affected severely. This lesion should be looked for preoperatively with a magnetic resonance imaging scan and intraoperatively by exploring the canal. This can be done at the time of the posterior surgery or during a second anterior surgical procedure.