Certified Neuroscience Registered Nurse (CNRN) Practice Exam

With which fractures is the incidence of fat emboli most common?

1. Wrist, ankle, and shoulder

2. Pelvic, rib, femur, and THA

3. Radius and ulna

4. Skull and vertebrae

The correct answer is: Pelvic, rib, femur, and THA

The incidence of fat emboli is most commonly associated with fractures of the pelvis, ribs, femur, and during total hip arthroplasty (THA). This correlation can be attributed to the fact that these areas of the body contain a significant amount of fat within the marrow of the bones. When a fracture occurs, especially in long bones like the femur or in the pelvic region, there is a higher likelihood that fat globules from the bone marrow can enter the bloodstream. Fat embolism syndrome (FES) typically manifests days to weeks after the injury and can lead to a range of symptoms, including respiratory distress, neurological changes, and petechial rash. The more extensive and vascular the area of injury, as seen in pelvic and femoral fractures, the greater the risk for fat globules to reach the circulation and cause complications. In contrast, fractures in the wrist, ankle, radius, ulna, skull, and vertebrae are less commonly associated with fat embolism due to the lower amount of marrow fat and the nature of their associated trauma. Thus, understanding the anatomical and physiological basis of fat emboli helps clarify why certain types of fractures pose a higher risk than others.