Bone marrow edema is a symptom of many diseases and can be used to make a preliminary diagnosis of many diseases, such as the following: a. Bone infectious diseases Bacterial infections, such as bone and joint tuberculosis, septic infections, or other types of bacterial or pathogenic infections, which are caused by an increase in the water content of bone tissue due to inflammatory cell infiltration, i.e. bone marrow edema. Bone and joint trauma The water content in the bone increases due to fracture, bone injury (although there is no fracture of the bone stem, but there is a fracture of the bone trabeculae), fatigue fracture, etc. Tumor In some bone tumors, especially malignant bone tumors, the water content of the lesion area or adjacent bone tissue increases due to the infiltration of tumor cells or other accompanying pathological factors. Ischemic diseases of bone Necrosis of bone tissue due to ischemia, in the progressive stage: interruption and fragmentation of bone trabeculae in the lesion area, which makes the water component of the necrotic area or adjacent bone tissue increase. V. Bone and joint immune diseases The most common are rheumatoid arthritis, ankylosing spondylitis, etc., due to the synovial membrane or tendon ligaments and other soft tissue proliferative lesions caused by bone lesions, bone lesion areas appear monocytes, lymphocytes and other inflammatory cell infiltration with increased water content. Sixth, degenerative osteoarthropathy Due to degeneration of the intervertebral disc or degeneration and destruction of articular cartilage, the formation of vertebral endplate inflammation or subchondral cystic degeneration or edema. VII. Hematologic diseases, such as leukemia, are accompanied by bone marrow edema due to bone marrow infiltration of leukemia cells. Other diseases such as transient bone marrow edema of unknown cause (for example, common femoral head and neck, which are self-limiting diseases of unknown cause); toxic bone diseases, such as cadmium poisoning, which cause osteolysis with bone marrow edema; gouty arthropathy (abnormal purine metabolism), etc.