Which factor is most associated with an increased risk of fat embolism syndrome after fracture?

• A. Advanced age
• B. Prophylactic antibiotics
• C. The fracture being in the upper extremity
• D. Multiple long bone fractures

Answer: (D)

Fat embolism syndrome happens when fat from bone marrow enters the bloodstream after a fracture, especially from long bones. The lungs are the first place these droplets travel to, so respiratory symptoms and hypoxemia are common, and neuro or skin findings can follow within the first couple of days. When multiple long bones are fractured, a much larger amount of marrow fat is released, increasing the embolic load and the likelihood that fat droplets lodge in the pulmonary circulation or travel to other organs. That higher embolic burden explains why multiple long bone fractures are the strongest risk factor among the options. Prophylactic antibiotics don’t influence fat embolism risk, and an upper-extremity fracture typically involves less marrow fat than a long-bone or pelvic fracture, while advanced age is a broader risk factor but not as specifically predictive of fat embolism as the extent of skeletal injury.