A nurse is assessing a child who has multiple closed fractures of the lower extremities due to a motor-vehicle crash. The nurse should monitor the child for which of the following complications during the first 24 hr after the injury occurred?

A. Compartment syndrome: Compartment syndrome is a serious and potentially life-threatening complication that can occur within the first 24 hours after fractures. It results from increased pressure within a muscle compartment, leading to decreased perfusion, pain, swelling, and neurovascular compromise, and requires prompt recognition and intervention. B. Osteomyelitis: Osteomyelitis, a bone infection, typically develops over days to weeks after an injury or surgery. It is unlikely to occur within the first 24 hours following closed fractures, making it a less immediate concern during initial assessment. C. Renal calculi: Renal calculi are kidney stones that develop over time due to metabolic or urinary factors. They are not an acute complication of closed fractures in the immediate post-injury period and are not a primary concern during the first 24 hours. D. Volkmann ischemic contracture: Volkmann contracture is a late complication of untreated compartment syndrome, typically developing days to weeks after the initial ischemic event. Monitoring for early signs of compartment syndrome is critical to prevent this long-term deformity.