Epidemiology
The true incidence and mortality rate of FES is unclear, mainly because there are often concomitant injuries and pre-existing problems. Fat embolism and milder forms of fat embolism syndrome may stay clinically undetected. In retrospective studies the incidence of FES is less than 1%, in contrast to the incidence of 11%-29% in prospective reviews.4-8 Differences in the diagnostic criteria and the over-diagnosis in prospective studies and under-diagnosis in retrospective studies are possible explanations for this varying incidence. The incidence of fat embolism in post mortem examinations rises up to 20%.9 It is estimated that fat embolisms occur in more than 90% of patients with fractures of the long bones or multiple injuries, patients undergoing intramedullary reaming and nailing, and patients undergoing total hip arthroplasty. These estimates are based on both postmortem findings in trauma victims as well as prospective studies that used either transthoracic or transesophageal echocardiography to monitor the “showering” of micro emboli through the heart and lungs that took place during certain corrective orthopedic procedures.10