A highly unstable and neurological injury, the isolated U-shaped sacral fracture without pre-pelvic ring fracture but combined with cauda equina injury is rare in clinics, and the treatment method remains unclear. It can occur when patients fall from a height, the lower extremities hit the ground in extreme flexion, and the sacrum is the direct touchdown point. The direct impact on the sacrum and the vertical extrusion energy through the spinal column may be the main mechanism of injury. The U-shaped sacral fracture is easily missed, and diagnosis is often delayed as it is difficult to detect on anteroposterior view pelvic radiograph due to angulation of the fracture and bowel shadow. When clinical signs suggested a possible U-shaped sacral fracture, a 2- to 3-mm cut computed tomography scan with coronal and sagittal reconstruction can provide optimal imaging to identify and evaluate the sacral fracture.This article describes 2 patients, a 16-year-old girl and a 40-year-old man, with U-shaped sacral fractures. The patients were treated with posterior sacral laminectomy within 1 week after injury and achieved satisfactory postoperative recovery. Follow-up showed bony union with no further displacement or internal fixation failure, wound infection, delayed healing, or compression of the skin by the plate and screws. The results show that posterior vertebral plate decompression and reconstructive plate internal fixation can obtain a satisfactory outcome with minor operation trauma and few complications.