Hi Alex,
As far as I know , simple fracture means a type which has no wound directly over the fracture site and thus it doesn't communicate with the exterior.And the another type, complex fracture means the one which is formed serious trauma to the skeletal system can involve ligaments, tendons, joints and multiple bones, and can include fractures caused from crushing, twisting, gun shots and other severe impact. Such kind of fractures require highly specialized surgical care at the time of injury and also may require subsequent treatment, as well.