A 6-year-old boy is hit by a car while crossing the street. He is intubated at the scene. A radiograph of his pelvis is shown in Figure A. He is hemodynamically stable and has no genitourinary injuries. CT scan of his abdomen and pelvis confirms symphyseal diastasis measuring 1.2cm and right sacroiliac joint diastasis measuring 0.7cm. What is the most appropriate next step in management?