Involvement of platelet activation in experimental osteonecrosis in rabbits

Osteonecrosis (ON) was produced experimentally in rabbits by intravenous in jection of platelet activating factor (PAF) in combination with lipopolysac charides (LPS) on two occasions separated by a week-long interval. Eleven o f 15 rabbits (73%), with administration of both LPS (50 mug/kg) and PAF (10 mug/kg), exhibited microcirculatory injuries including extravasation of er ythrocytes into sinusoidal spaces and formation of microthrombi in arteriol es near regions of erythrocyte extravasation. Seven of 15 rabbits (47%), wh ich received both LIPS (50 mug/kg) and PAF (10 mug/kg), exhibited necrosis of trabeculae and 8 of 15 (53%) exhibited bone marrow necrosis. In addition , PAF receptor antagonist (0.3 and 3.0 mg/kg) significantly reduced the inc idence of trabecular necrosis (0%) in this model. The findings of the prese nt study suggest that platelet activation may play an important role in ind ucible ON, and that suppression of platelet activation may contribute preve ntion of ON.