Normal femoral head radiographs are actually orthopantomograms of the hip joint or orthopantomograms of the pelvis, which are shadows of the overlapping acetabular femoral heads. In normal people, orthopantomogram of the hip joint shows that the femoral head in the bilateral acetabulum is smooth in shape, the gap is normal, the tissue density inside the femoral head is uniform, and there are many cords of trabeculae, and the arrangement of the trabeculae is close and regular, and there is no thickening or thinning of the bone cortex. If femoral head necrosis occurs, X-ray examination may show that the femoral head is flattened, and in serious cases, even the femoral head gap disappears and the femoral head collapses. In the case of osteoarthritis, X-ray examination may show that the gap of the femoral head becomes smaller, the sclerosis of the bone surface of the neighboring joints is obvious, and some patients may have bone cysts in the neighboring joints. X-ray can effectively penetrate soft tissues but not bone tissues, so it is widely used in orthopedics, especially for diagnosing fractures of limb bones, X-ray is preferred, which can well reflect the structure of bones.