Necrosis of the femoral head is not a tumor disease, and certainly not a malignant tumor or cancer. Necrosis of the femoral head is mainly caused by the blood circulation of the femoral head being damaged, resulting in abnormal metabolism of the bone of the femoral head, which leads to the hardening, degeneration, hyperplasia, and collapse of the bone, resulting in pain and dysfunction of the hip joint. Compared with tumor, it is caused by the destruction of blood circulation of bone and abnormal metabolism of bone, not the destruction or invasion of bone and metastasis of tumor, which necrosis of femoral head does not have, so necrosis of femoral head does not have the characteristics of tumor, and of course, it does not have the characteristics of malignant tumors and cancers, so necrosis of femoral head is just a local metabolic lesion of the femoral head.