The Research Of Canine Femoral Head Necrosis Model Constructing By Endovascular Technique

Objective:To establish a femoral head necrosis canine model by endovascular technique, and investigate the operational feasibility and effect. All this is to provide an excellent model support for researching the treatment of femoral head necrosis.Methods:Nine healthy adult canines were anesthetized,then punctured right femoral arteries with Seldinger technique and superselected the arteries which supply left femoral head, filled with Pingyangmycin and embolized with gelfoam particles to establish the femoral head necrosis models while the right femoral heads were served as nonischemic controls. The model canines were randomly ranged to group A,B and C with 3 in each group and put to death at the 2nd,the 4th and the 6th week respectively after embolization. All canines were detected hemorrheology changes and scanned both coxa joints with magnetic resonance imaging(MRI)before the operation and per week after the operation. Digital subtraction angiography(DSA) on both arteries which supply femoral heads was performed before and after the procedure. The last angiography was done on these canines before they were sacrificed,then their femoral heads were taken out for pathological study.Results:(1)After embolization,no case in all canines was infected or dead,and no skin or muscle tissue necrosis emerged in the embolized limbs. One week after operation, the canines were in poor mental state and got significant weight loss,while the embolized limbs were in claudication. After one week,their mental state were getting better and better, the state of the embolized limbs changed from claudication to weight-bearing and the weight got restored gradually, too.(2)According to the analysis of hemorrheology results,the animal blood consisted with hyperviscosity state in the process of femoral head osteonecrosis after operation, whose manifestations were that the whole blood viscosity and the erythrocyte aggregation increased, while the red blood cell deformation capacity decreased. The state of high blood viscosity formed in the early period after the operation when MRI hadn't shown unusual performance and it has been with the models in the whole process.(3) Through the pre-test observation of anatomy and angiography, blood supply for the canine femoral head mainly comes from the internal iliac artery branch of the hip joint and the median sacral artery branch of the hip joint. Right after embolization, the angiography showed all distal end artery trunks of the femoral head were occluded. All occluded arteries were not recanalized on the angiogram at the 2nd,4th and 6th week after operation. With the extension of time,the remain proximal trunk of the embolized arteries shrinked gradually. At the 6th post-operation week,2 of the 3 canines angiography appeared completely occluded in the proximal trunk of hip branches which come from the embolized median sacral arteries.(4) MRI observation: For the first three postoperative weeks, both femoral head signals in all model canines had no significant difference comparing with preoperative period. At the 4th week after operation,4 in 6 canines appeared the embolized femoral head diffuse non-uniform signal on T1 and T2-weighted images. At the 5th and 6th week, the femoral head embolized side of the remain 3 canines showed mixed non-uniform signal on T1 and T2-weighted images, and the scope expanded over time when the T1-weighted images manifested mainly to low signal and the T2-weighted images manifested mainly to mid-low signal.(5)Histopathology observation: The model femoral head pathological sections appeared earlier period necrosis change that the bone marrow hematopoietic stem cells occurred necrosis and the fat cells appeared integration with part necrolysis at the 2nd week after embolization. At the 4th week,the pathological sections suggested all embolized femoral heads showed osteonecrosis at different levels. Moreover, at the 6th week,the pathological section indicated proliferation and restoration after osteonecrosis.Conclusions:Canine femoral head necrosis model can be created with the endovascular technique,which owns characteristics of microinvasion,simpleness,short time and low animal mortality,so it is an ideal model-creating method.