Causes
Orthopaedic injuries especially fractures of the long bones are the most common cause of fat embolism syndrome (FES). The rates of fat embolism in long bone fractures vary from 1% to 30%. The mortality rate of fat-embolism syndrome is approximately 10–20%. However, fat globules have been detected in 67% of those with orthopaedic trauma and can reach as high as 95% if the blood is sampled near the fracture site. As the early operative fixation of long bone fractures became a common practice, the incidence of FES has been reduced to between 0.9% and 11%. Other rare causes of fat embolism syndrome are:
Severe burns
Liver injury
Closed chest cardiac massage (during cardiopulmonary resuscitation)
Bone marrow transplantation
Liposuction
Parenteral lipid infusion
Decompression sickness
Extracorporeal circulation
Acute haemorrhagic pancreatitis
Alcoholic liver disease
Prolonged corticosteriod therapy
Sickle cell disease
Carbon tetrachloride poisoning
Osteomyelitis

Pathophysiology
Once fat emboli enter the blood circulation, they can lodge at various sites of the body, most commonly in the lungs (up to 75% of cases). However, it can also enter the brain, skin, eyes, kidneys, liver, and heart circulation, causing capillary damage, and subsequently cause organ damage in these areas. There are two theories that describe the formation of a fat embolus:
Mechanical theory - Following trauma, fat is released directly from the bone marrow into the circulation. This is because after trauma, an elevated pressure in the medullary cavity (central cavity of the bone where the bone marrow are stored) causes the release of fat globules into the venous system supplying the bone.
History
In 1861, Zenker first reported on the autopsy findings of fat droplets found in the lungs of a railway worker who died due to severe thoraco-abdominal crush injury. In 1873, Bergmann diagnosed fat embolism clinically in a patient with fractured femur. In 1970, Gurd defined the characteristics of this phenomenon. Gurd later modified the fat embolism criteria together with Wilson, thus producing Gurd and Wilsons criteria for fat embolism syndrome in 1974. In 1983, Schonfeld suggested a scoring system for the diagnosis of fat embolism syndrome. In 1987, Lindeque proposed another scoring system that diagnose fat embolism syndrome by using respiratory changes alone. However, none of them have become universally accepted in the medical community.In 2015, Singaporean couple Pua Hak Chuan and Tan Hui Zhen were charged with the abuse and murder of Annie Ee Yu Lian, who died due to multiple physical abuse which lasted for eight months before her death. The cause of death was revealed to be acute fat embolism, which resulted from the blunt force impact caused by the beatings, which led to the fatty tissue entering the bloodstream and eventually entering the blood vessels in the lungs, which led to a blockage and cut off the circulation of oxygenated blood and led to Ees death by respiratory and cardiac failure. Two years later, for reduced charges of voluntarily causing grievous hurt with a weapon, Tan was sentenced to 16 years and six months in jail while Pua received 14 years imprisonment and 14 strokes of the cane.