An 18-year-old woman involved in a motor vehicle accident sustained a vertical shear fracture of the sacrum accompanied by unilateral dislocation of the L5-S1 joint. Evaluation of the patient's injuries was defined by computed axial tomography. Through a posterior midline incision, open reductions of the dislocated L5-S1 joint and of the sacral fracture were performed. Reduction was followed by anterior stabilization of the symphysis pubis. The patient remained neurologically intact after surgery.