Multimodality Imaging, Pathological Change And Clinical Treatment Of Osteonecrosis Of The Femoral Head

Osteonecrosis of the femoral head(ONFH), a relatively refractory disease in younger, active patients seemingly has a wide range of etiologies and a poorly understood pathogenesis. One of the most common risk factors for ONFH is use of corticosteroids. After onset of ONFH,pathological changes, blood supply changes, bone parameters changes of the necrotic femoral head and correlations among them are essential for the diagnosis, treatments and prognosis of this disease. Imageological techniques are indispensable for ONFH diagnosis and staging, thus their accuracy are preconditions for successful treatment. Several studies have introduced many methods for measurements of the necrotic lesion, including X ray, Computed Tomography(CT) and Magnetic Resonance Imaging(MRI). To diagnose and treat ONFH properly, it is undoubtedly important for the researchers to find a manipulable and accurate lesion size evaluation technique.There are various methods for treatment of ONFH, it is generally accepted that surgical techniques should apply for post-collapse ONFH cases.Surgical treatments of core decompression,vascularized or nonvascularized bone grafting and osteotomies were applied for younger ONFH patients, however, clinical results were reported inconsistently because of inconsistent staging system, evaluation methods and surgical techniques, because there is no common agreement as to which method for treating ONFH is the best.Firstly, In this study, necrotic hips were evaluated by X ray and MR I before surgery Micro CT data of specimens of femoral head were obtained after total hip arthroplasty and then analysed with Mimics software. The extent of osteonecrotic involvement of the femoral head was determined through use of three different methods:the volume of necrosis by quantitative Mimics analysis, and the angular measurements described by Kerboul et al.and MRI analysis described by Kim. The results showed that Kim technique based on MRI evaluation is more precisely and easy to apply. Hemodynamic parameters of the Association Research Circulation Osseous (ARCO) stage ?-? cases were observed preoperatively, femoral head specimens were taken after total hip replacement and trabecular bone parameters, pathomorphology, bone histomorphometry was observed.According to the micro-CT results, significant changes of trabecular parameters were found in necrotic region of ARCO ? stage femoral head, while in the sclerotic and compression trabecular region the parameters changes were less remarkable. These findings indicated an irreversible necrotic lesion progressed from ARCO ? to ARCO ?. Significant changes of trabecular parameters were found in necrotic region, sclerotic region and compression trabecular region of ARCO ? stage femoral head. While of the ARCO ? stage necrotic femoral head, trabecular parameters changed significantly in all the six measured region, indicated that irreversible progression of this disease.Our hemodynamical and pathological studies found that early stage of ONFH characteristic presented as venous stasis and advanced stages presented insufficient artery blood supply to the femoral head. Bone repair was consistent with the changes of microstructure of trabecular, osteogenesis lagged behind osteoclasia of the trabecular, and cystic region was filled with fiber connective tissue.After rapid osteoclasia, osteogenesis process lost its original framework however enough artery blood supply led to multiple osteogenic foci intra-bone marrow cavity and coexistence of sclerotic bone, necrotic bone and cystic lesion. Bone histomorphometrical and pathological study both revealed that during the process of femoral head collapse, the trabecular parameters changed and hemodynamic changed accordingly.Secondly, this study observed the nature history of asymptomatic ONFH. As nontraumatic ONFH is typically discovered as the contralateral hip of a patient with one symptomatic joint. Symptomatic hips generally progress to femoral head collapse and hip osteoarthritis if they are not properly treated. While not all necrotic lesions cause hip pain, to understand the nature history of early stage ONFH is essential for further treatment.The results of this study revealed that there is a high risk of progression into symptomatic disease when the necrotic lesion occurs on the lateral and lateral central or later-central-medial region of the femoral head and joint-preserving surgical treatment should be considered in these types of ONFH. However, asymptomatic small and medially located lesions may be managed conservatively with closely medical imaging observations.Lastly, based on anatomy findings, young ONFH patients were treated with the greater trochanteric bone flap pedicled with transverse and gluteus medius branches of the lateral circumflex femoral artery double blood vessels. The overall Harris hip score improved significantly. The results of this study suggest that this procedure is relatively easy to perform, less donor-site morbidity and useful for young patients with stages ? to ? disease with or without mild collapse of the femoral head.