Instability resulting from a missed Chance fracture

An 11-year-old boy was a lap-belted back-seat passenger involved in a highspeed head-on motor vehicle accident. At the scene the boy was alert, oriented and hemodynamically stable but complained of abdominal pain. He was flown by air ambulance to hospital where he was firther assessed by the trauma team in the Emergency Department. On inspection of the abdomen, a "seat-belt sign" was evident at the level of the umbilicus. Abdominal examination revealed guarding and rebound tenderness. "Log rolling" the patient demonstrated a large hematoma in the mid-lumbar region. Initial films that included cervical spine, anteroposterior chest and anteroposterior pelvis appeared normal. Since the patient was hemodynamically stable, CT of the abdomen was performed, revealing thickened loops of bowel and free fluid within the peritoneal cavity, indicative of hollow viscus rupture. At exploratory laparotomy a small-bowel blowout was found, which was repaired without difficulty. Postoperatively, he went immediately from the recovery room for completion of cervical, thoracic and lumbar spine films (Fig. 1). These were interpreted as normal. Postoperatively, the patient slowly began to ambulate despite severe back pain and had an otherwise uncomplicated hospital course before being discharged on postoperative day 5. "Seat-belt syndrome" is characterized by injury to intestinal viscera and mesentery along with an associated lumbar spine injury, usually a Chance type fracture secondary to a flexion-distraction injury about a lap-type seat belt. Children presenting with a seat-belt sign have intestinal injuries in up to 78% of cases and lumbar spine injuries in 21%.6 Further, an alarming 50% of abdominal injuries are missed initially and identified more than 24 hours after presentation.3 Up to 30% of spine injuries are also missed on initial presentation.2 Careful history-taking, physical examination, careful scrutiny of the radiographs for subtle signs and a degree of suspicion based on the mechanism of injury are the keys to making the diagnosis. In our case, the combination of a significant ecchymosis and widening of the posterior disc space were definitive signs of an underlying spinal injury.