Objective:To investigate the effect of Huogu Ⅱ formula and its combination with different meridian-guiding herb on the expression of vascular endothelial growth factor（VEGF） in the femoral head of rabbits with osteonecrosis of the femoral head（ONFH）

as well as to explore the mechanism of prevention and treatment for ONFH.Method: The animal model of ONFH was established by liquid nitrogen frozen in the rabbit left hind leg.Ninety-eight.Japanese white rabbits were randomized to sham-operated group

model group

Huogu Ⅱ group and Huogu Ⅱ plus achyranthes root

Pubescent angelica

asarum and Balloonflower respectively

evenly 14 in each group.During the course of ONFH animal model establishment

all the rabbits were subcutaneously injected with recombinant human granulocyte colony-stimulating factor（rhG-CSF）（30 μg·kg-1·d-1

for continuous 7 days）.Meanwhile normal saline and decoction of the formulae were administrated by gavage respectively.Materials were drawn at the second and forth week after model establishment Histopathological changes were observed by HE staining

vascular morphology was observed by ink perfusion

VEGF was measured by immunohistochemical assay in femoral heads of the left hind leg.Result: Compared with sham-operated group

the ratio of empty lacuna increased sharply

vessel area and VEGF levels decreased obviously in the model group.But in comparison with the model group

the empty lacuna ratio of Huogu II group decreased obviously

vessel area

VEGF increased significantly.Compared with Huogu II group

the empty lacuna ratio decreased and vessel area increased significantly at the forth week

and the expression of VEGF increased both at the second and forth week in the achyranthes root group.As for the balloonflower group

empty lacuna ratio showed the increase potention trend

and the number of VEGF-positive cells decreased obvious at the forth week.There were no significant changes in Asarum and Pubescent angelica combination group.Conclusion: The medicinal guide achyranthes root could enhance the effect of Huogu Ⅱ formula to increase the expression of VEGF in the ONFH animal model.It may contribute to the preventive and therapeutic effect for ONFH.