Early diagnosis of osteonecrosis of the femoral head has two meanings, one is the diagnosis before the appearance of clinical symptoms and the other is the diagnosis after the appearance of clinical symptoms. To diagnose osteonecrosis before clinical symptoms appear, we need to rely on the popularization of medical knowledge among the general public and the improvement of awareness of osteonecrosis and close cooperation among doctors of various clinical disciplines in order to detect early (subclinical) osteonecrosis that has not yet developed clinical symptoms in people who are at risk of developing osteonecrosis. At present, the most valuable examination is magnetic resonance imaging (MRI), which has a diagnostic accuracy of 99% for osteonecrosis. For the diagnosis of clinical symptoms, the current problem is that many patients, for various reasons, have long thought that it is a sprain, or mistaken as “rheumatism” or “lumbar disc herniation”, etc. Delaying the diagnosis means losing the opportunity of early treatment. The consequences are very serious. The following focuses on how to timely diagnose femoral head necrosis after clinical symptoms appear. 1, understand whether there is a history of hormone treatment or alcohol abuse: the main cause of non-traumatic femoral head necrosis is the history of hormone (prednisone, methylprednisolone, dexamethasone, etc.) use and long-term alcohol abuse. Therefore, for young and middle-aged people who have no previous history of trauma or disease in the hip joint, if they suddenly feel pain in the hip or knee, or have limited movement of the hip joint, they should go to a joint specialist to consult with a specialist in a timely manner. In this case, the doctor needs to speculate whether to take hormone therapy by understanding the medical history and the reaction after taking the medication, such as whether there is obvious obesity and increased appetite after taking the medication. Usually lupus erythematosus, nephritis, asthma, skin diseases, post-organ transplantation, viral encephalitis, coma patients, allergic diseases, other immune diseases, etc., most of them need long-term high-dose hormone therapy. For those who usually prefer to drink alcohol, the patient should tell the doctor the specific drinking situation to assist the doctor’s diagnosis. The high-risk group of alcoholic femoral head necrosis is usually those who drink about 250 grams of high alcohol per day on average for more than 10 years, but of course there are many other causes of non-traumatic femoral head necrosis, such as decompression sickness, certain blood diseases, pancreatitis, pregnancy, etc. In addition, there are a few patients who cannot find the cause. It is called idiopathic necrosis of the femoral head. 2, clinical symptoms and signs: hip pain radiating to the inguinal region or the posterior hip, lateral or medial knee, hip stiffness, weakness, restricted movement, inflexible leg lifting, cross-legged or outward skimming of the leg, squatting difficulties, limping, etc. When examining the patient, it can be found that the muscles of the affected thigh are atrophied, and the internal and external rotation and abduction of the hip joint are restricted to different degrees. 3, imaging examination: in general, by taking clear double hip orthogonal frog X-rays, most patients can obtain a preliminary diagnosis, but to further understand the details and develop a treatment plan, MRI and CT examination must be made.