A Case of Lateral Lumbosacral Dislocation with Cauda Equina and Dural Injury Treated by Posterior Reduction and Fixation.

A 28-year-old woman was transported to our hospital after falling from a motorcycle. On arrival, she presented with numbness and sensory disturbances distal to both lower legs, along with right-dominant lower limb paralysis. The anal sphincter was relaxed. Imaging revealed bilateral dislocation of the L5/S1 facet joints and rightward displacement of the L5 vertebra. On the same day, open reduction of the L5/S1 dislocation was performed via a posterior approach. Intraoperatively, cerebrospinal fluid leakage was observed during reduction, and the dural tear was repaired with primary suturing. Posterior instrumentation from L3 to the pelvis was performed, and posterolateral bone grafting was conducted at L5/S1. At three months postoperatively, although numbness in both feet persisted, muscle strength had recovered, and the patient was able to urinate and defecate voluntarily. While dislocations of the lumbosacral junction accompanied by fractures of the facet joints or pedicles have been reported, dislocations without associated facet fractures are rare, and lateral dislocations are even more uncommon. Previous studies have suggested that reconstruction of the anterior column contributes to improved bony fusion in lumbosacral injuries. In the present case, due to the need for emergency nighttime surgery, an interbody cage could not be prepared. Therefore, long-segment posterior instrumentation from L3 to the pelvis was selected. Implant removal is planned following confirmation of solid bony fusion.