Abstract
Background: Acute traumatic spondylolisthesis of lumbosacral junction is a rare injury and easy to be missed in the emergency room. About 80 cases (few cases of bilateral fracture of parsinterarticularis and lateral dislocation) were reported in the literature. This injury usually occurs after a high- energy trauma in a patient with multiple traumas. Surgical treatment of these cases is the choice and only few cases were treated conservatively.
Case Report: Case 1: a 31-year-old man got a direct hit on his lower back by a heavy object. It caused sever skin injury, paresthesia and weakness in both feet. Radiographs showed grade three spondylolisthesis of the lumbosacral junction, bilateral fracture of pars interarticularis of the fifth lumbar vertebra and fracture of the right transverse process of the forth lumbar vertebra. The patient was misdiagnosed for three days. Surgical reduction and lumber interbody fusion was done. Case 2: an 18-year-old man got a direct trauma on his lower back. He developed weakness and paresthesia of both lower limbs in addition to loss of sphincters control. Radiographs showed lateral dislocation of L5 and fracture of the right facet that reached the vertebral body. He was misdiagnosed for one day. We treated him with in situ fixation and decompression.
Conclusions: As these injuries are caused by a high-energy trauma and associated with severe injuries, it is easy to be misdiagnosed in the emergency department. We advise to carefully assess these patients clinically and radiologically. Surgical treatment is advisable for these unstable injuries.

Keywords: Acute Spondylolisthesis, Lateral Dislocation, Lumbosacraral Junction