Variation Of Arteriovenous Blood Supply In Glucocorticoid-induced Femoral Head Necrosis And Its Opplication To Clinical Treatment

Avascular Necrosis of the Femoral Head(ANFH)can be classified as traumatic and nontraumatic femoral head necrosis according to the pathogenic factor.Most cases of traumatic femoral head necrosis has a clear traumatic factor that causes vascular injuried.It is difficult to find a clear cause of "ischemia" for traumatic femoral head necrosis,or it is difficult to take effective measures to prevent necrosis due to the complicated pathogenic factors.If no treatment intervened,ANFH will practically progresses to later stages result in patient with severe hip pain and significantly limited joint function.Although hip joint replacement can relieve the patient's hip pain and improve the joint motion significantly,but it is not an ideal treatment because of the prosthesis survival and many complications.Therefore,how to prevent or delay the progress of necrosis with reasonable treatment in order to preserve the patient's hip joint has become a therapeutic goal.Mastering the pathophysiological characteristics of e'very stage ANFH is a prerequisite for effective treatment.Femoral head blood supply plays a key role in the morbidity and progress of ANFH.Therefore,research on the femoral head blood supply is crucial for the treat:ment of this disease.Based on the research of canine femoral head blood supply,the experimental canine model of glucocorticoid-induced femoral head necrosis was successfully established in this study.Digital Subtraction Angiography(DSA)technique combined with the techniques of vascular perfusion,histopathology,and magnetic resonance imaging(MRJ)were used to characterize the dynamic chang of femoral head blood supply in vivo.The mechanism and process of glucocorticoid-induced ANFH were studied via the femoral head blood supply changes.Based on this theory,clinical treatments were guided according to the staging of the femoral head blood supply.The main contents and achievements of this research are as follows:(1)DSA technique was used for dynamic characterization of femoral head blood supply in vivo,and quantitative methods of arterial phase,venous phase and microcirculation phase were established.It was found that the venous phase was first extended during the early stage(4 weeks after drugs induction)of ANFH.The microcirculation phase and the arterial phase extended successively as the necrosis progressed(8 weeks after drugs induction).The blood supply pathological process of glucocorticoid-induced ANFH was summarized as the dynamic process of venous stasis,arterial ischemia and arterial occlusion.MRI examination also confirmed this conclusions supplementally.(2)Femoral head vascular perfusion was performed on the experimental animal model.Three-dimensional composition was established via micro-CT scanning.It was found that the number of blood vessels in the necrotic femoral head was significantly reduced,a large number of vascular terminal branches disappeared,and the blood vessel volume fraction was significantly reduced.Pathological observation of animal models' femoral head showed that the artery and venous system were changed similarly corresponding to the DSA examination.Resuts:The venous system occurred pathological changes firstly in the early stage necrosis.The changes of the venous system manifested as venous stasis with the features of intima incrassation and significantly narrowed lumen;The arterial system was involved with the necrosis progressed.The characteristics of intima thicked and constriction significantly increased was found in arterial system.The pathological findings further confirmed that the blood supply disorder at the early stage of ANFH was mainly venous system lesions,and the arterial system lesions appeared at the advanced stage.(3)Based on the blood supply type of glucocorticoid-induced ANFH,patients with early stage ANFH were treated with core decompression.Core decompression can effectively relieve the venous stasis at the early stage of necrosis,thereby improved the femoral head blood circulation and promoted regeneration of vessels and bone tissue.So could avoided or delayed the collapse of the femoral head.Necrosis of all cases were ? stage according to ARCO(Association Research Circulation Osseous,ARCO).DSA was used for preoperative evaluation in order to divided the femoral head blood supply into venous stasis type and arterial ischemia type.Clinical results showed that core decompression can significantly delay the progress of ANFH with venous stasis.(4)The technique of vascularized bone grafting combined with tantalum rod implantation was used to preserve the hip joints for young patients with middle and advanced ANFH because of arterial occlusion.The clinical results showed that the overall hip survival rate was 87.5%.The excellent and good rate of the Harris score was 89%.Radiologic evaluation showed that the bone flaps and femoral heads healed well in all cases,and 76%of the femoral heads remained stable with no progress in ARCO staging.Vascularized bone grafting combined with tantalum rod implantation can increase the blood supply and improve mechanical strength for the femoral head,restore the contour and reconstruct the function of the femoral head,thereby delay or avoid hip replacement.It provides an effective method for the treatment of ANFH at the middle and advanced stages.