Can X-ray and CT not detect early avascular necrosis of the femoral head? MRI might be a big help

In the early stage of avascular necrosis of the femoral head, bone marrow necrosis and trabecular bone structure have not disappeared, ordinary X-ray film and CT scan can not show the changes of femoral head structure, X-ray and CT can not detect stage I femoral head necrosis, the diagnosis of early femoral head necrosis depends on MRI. It is true that MRI is the most accurate method for the early diagnosis of avascular necrosis of the femoral head. When the bone marrow changes in the early stage of femoral head necrosis, the corresponding changes can be found in MRI. Although MRI signal is very sensitive to various bone abnormalities, it lacks specificity. On the other hand, MRI is less sensitive to subchondral bone fracture and femoral head collapse. On T2 weighted images of hip joint, there was a high signal band inside the low signal band surrounding the osteonecrosis, which was the so-called “double line weighted image” with band or ring low signal band surrounding a high signal area in the femoral head, which is the characteristic manifestation of early avascular necrosis of the femoral head. Therefore, it is necessary to take lateral radiographs of the femoral head and neck at the same time during the X-ray diagnosis or treatment follow-up of patients with osteonecrosis of the femoral head. Frog position of hip joint is commonly used in clinic. The frog position X-ray film of hip joint refers to the lateral position film of femoral head and neck of hip joint obtained by the patient lying on his back on the camera bed, bilateral hip and knee joints as far as possible flexion and external rotation of the hip joint at the same time. HEALTHY LIFE