A 9-month-old male infant is brought to the emergency department with a history of "falling from the bed" 2 days ago. On examination, he is irritable with bruising over the torso and ears. Skeletal survey reveals the finding marked **A** in the diagram — a metaphyseal corner fracture of the femur — along with posterior rib fractures and healing callus from an older fracture. The infant is non-ambulatory and has no history of significant trauma. Which of the following is the MOST appropriate next step in management?