The risk of fat embolism is greatest when the long bones are reamed and the insertion of internal nails bilaterally. It can also happen when doing exfix only and long bone fractures. This is one of the main reasons why some doctors may prefer operating one leg at a time in order to reduce the chances of developing fat embolism.
There are some studies online that show prophylactic methylprednisolone may reduce fat embolism during fractures.