Fat embolism syndrome is caused by traumatic and nontraumatic conditions, and most commonly associated with fractures of long bones of the lower extremity. Clinical manifestation of the fat embolism syndrome occurs in a minority of patients with fat emboli. The incidence of fat emboilsm has been reported 5-10%. The pulmonary symptoms of fat embolism are clinically important but hard to diagnose, so treatment was often delayed. The purpose of this study is to search for the development of fat embolism after long bone fracture of rabbit, and to demonstrate pulmonary fat embolism by high resolution computerized tomograhy (HRCT) and pathologic findings.

Twelve rabbits (Newzealand, 2.5-3 Kg) were divided into 2, 24, 72 hours and control groups after closed tibiofibular fracture. The presence of involvement was classified by high resolution computerized tomography with ground glass opacity, consolidation and focal hyperlucency. The extent was measured by 10% grading scale. Gross inspection, histologic examination and histochemistry (Oil red 0) were performed in removed lungs.

Ground glass opacity was found in 100% of test subjects, consolidation was found in 89%, bronchovascular bundle thickening was found in 78% and focal hyperlucency was found in 33%. Fat embolism was developed in all groups with the 24-hour group showing maximal changes. Microscopically the vessel was occluded with fat globule which was stained with Oil red 0 stain.

The abnormal density lesion on HRCT was correlated with pathologic finding and was induced by fat emboli after long bone fracture of the rabbit