X-ray examination is the main means and basis for clinical diagnosis of this disease. Regularly taking orthopantomogram and frog X-ray of both hips can dynamically observe the changes in the whole lesion process. Combining the four stages of the pathological process, the X-ray performance is usually divided into four stages. Stage I (synovitis stage) The main manifestation is swelling of the soft tissue around the femoral head. The femoral head is mildly displaced laterally, i.e. the head and socket distance is widened, but generally not more than 2-3 mm. the joint gap is slightly widened. The femoral head epiphysis shows mild osteoporosis. Stage II (ischemic necrosis stage) The main manifestation is that the femoral head epiphysis shows uneven density increase image and the bone texture disappears. If the necrosis is located anterolaterally, the hyperdense portion of the frog radiograph is limited to the upper anterolateral aspect of the epiphysis. In the case of total epiphyseal necrosis, a flattened deformity is often observed. Stage III (fragmentation or regeneration stage) The main manifestation is the interspersed distribution of sclerotic and sparse areas. The femoral neck becomes shorter, wider, and necrotic, and the corresponding epiphysis of the femoral head appears lesioned, with osteoporosis in mild cases and cystic changes in severe cases. The epiphysis is irregular, or closes prematurely. IV (healing or sequelae phase) The main manifestation is that the epiphyseal density tends to be uniform, but the femoral head epiphysis is significantly enlarged and deformed (such as oval, flattened, mushroom-shaped, saddle-shaped). Subluxation of the hip joint. The shape of the acetabulum also changes accordingly with the femoral head, such as becoming shallow, enlarging, and increasing the medial gap.