Circulating platelet-derived microparticles and endothelium-derived microparticles may be a potential cause of microthrombosis in patients with osteonecrosis of the femoral head

Introduction: To test the hypothesis that the platelet microparticle (PMP) and endothetial microparticle (EMP) may contribute to the hypercoagulability associated with microvascular thrombosis in patients with nontraumatc osteonecrosis of the femoral head (ONFH). Materials and methods: The study comprised 46 patients who had been diagnosed with ONFH and 20 control subjects. The plasma was ultracentrifuged, and then PMPs and EMPs were examined by the flow cytometry. The thrombotic and fibrinolytic disorders were investigated. Results: The numbers of PMPs expressing P-selectin and CD42a and EMPs expressing E-setectin and CD31 in the ONFH patients were significantly higher than those in the controls (P < 0.001). The number of MPs was correlated with the level of the serum Creactive protein (CRP) (r=0.661, P < 0.001), but there was a poor correlation between the MPs counts and the risk factors for ONFH (P > 0.05). The mean levels PAI-1, F1+2, and TAT were higher in the patients with ONFH than in the controls (P < 0.05). Conclusions: The elevated numbers of PMPs and EMPs may contribute to hypercoagulability in the ONFH patients. This may provide important pathophysiological insights into the hypercoagulabitity associated with nontraumatic ONFH and have implications for pharmacological prevention and treatment of ONFH. (C) 2008 Elsevier Ltd. All rights reserved.