U-shaped sacral fracture is a very rare injury. This injury is easily missed and the diagnosis is often delayed as it is difficult to detect on the anteroposterior view of the pelvic radiograph. It is highly unstable and neurological injury is common. Two cases of U-shaped sacral fractures are reported here in which the diagnosis was delayed resulting in the late development of cauda equina syndrome. In these two cases, full recoveries were achieved following surgical decompression. A high index of suspicion with proper clinical and radiographic assessments will decrease the incidence of missed diagnosis and prevent the occurrence of delayed neurological deficits.
A 63-year-old man developed acute cauda equina syndrome due to fat graft compression. Following decompressive laminectomy and posterior instrumented fusion with pedicle screw fixation for spinal stenosis of L5 and S1 vertebral levels, free fat grafting was performed to cover the exposed dura. The patient developed gradual neurological deficit three days postoperatively. This started with sensory loss and weakness of the affected dermatomes and myotomes, followed by bowel incontinence on the 12th postoperative day. Intraoperatively, significant dural compression by the fat graft was confirmed. Immediate removal of the fat graft resulted in recovery from cauda equina syndrome.