The treacherous SARS more than 10 years ago has left us, but there are a lot of problems left behind, and osteonecrosis is one of them. According to rough statistics, 1/3~1/2 of the medical personnel infected with SARS in Beijing have osteonecrosis. In your life you may have heard of someone who had a long term alcoholism, as a result of which the femoral head necrosis, and had surgery to replace the metal joint. “Can a bone be necrotic and still walk?” Are you feeling particularly confused and puzzled? What exactly is osteonecrosis and what are its consequences? In fact, this kind of osteonecrosis is mostly manifested as osteonecrosis of the femoral head, but some people also have osteonecrosis of the ankle, knee and shoulder joints. Osteonecrosis is not obvious in the early stage, resulting in a high rate of misdiagnosis and underdiagnosis. Once osteonecrosis occurs, if untreated, at least 80% of patients will follow the development pattern of “necrosis-collapse-osteoarthritis”, which gradually leads to partial or complete loss of joint movement and walking function along with joint pain, which is a very serious danger. Let’s talk about what is osteonecrosis? How to early detection? First, what is osteonecrosis? Osteonecrosis, also known as aseptic osteonecrosis or ischemic osteonecrosis, refers to the pathological process caused by the death of viable components of bone (including bone cells, bone marrow hematopoietic cells and adipocytes). It is commonly found in the femoral head, humeral head, femoral condyles, proximal tibia, and bone tissue of the foot, ankle, and wrist, with the femoral head being the most susceptible and often involved bilaterally. Therefore, this article mainly discusses aseptic necrosis of the femoral head as an example. Second, how can we detect osteonecrosis of the femoral head at an early stage? 1, pay attention to the sensitive factors related to the development of femoral head necrosis Trauma (especially femoral neck fracture), decompression sickness, radiation injury, Gaucher’s disease, hemoglobinopathy, steroid corticosteroids, alcoholism, etc.. Trauma, alcohol and hormone are the three most common clinical causes. 2, clinical manifestations Femoral head necrosis early symptoms less or even no performance, pain is often the earliest symptoms of femoral head necrosis, usually chronic hidden pain, but the pain symptoms are not long-term persistent, by rest or reduce activity, symptoms tend to reduce or disappear on their own. Some patients only feel discomfort in the hip, buttock and the back of the thigh, and there may be varying degrees of swelling and joint dysfunction in the painful area. These mild symptoms are often overlooked by patients. In addition, these symptoms are not specific, and the receiving doctor lacks experience or the equipment of the hospital is limited, so the disease is often missed or misdiagnosed as “rheumatism” or “lumbar disc herniation” and other diseases. This pain can occur before or after a positive X-ray finding. Recurrent attacks of pain, especially when relief is not obvious, suggest aggravation of the disease. Patients with femoral head necrosis may develop claudication and disuse atrophy of the muscles of the affected limb in the middle and late stages. Restriction of movement of the affected hip in all directions, mainly internal rotation and abduction, pressure pain in the inguinal midpoint, muscle atrophy in the quadriceps muscle is significant, easy fatigue and walking weakness may occur. 3, auxiliary examination ① X-ray examination X-ray is currently the most commonly used method to diagnose osteonecrosis, is also a common effective method to observe the effect of osteonecrosis treatment, with simple, intuitive, convenient, economic characteristics. However, the discovery time lags behind, which is not conducive to early examination. In the early stage, there is often no positive manifestation on the X-ray film. In the middle stage, obvious necrotic areas, decreased and increased bone density appear at the same time, positive “crescent sign”, and collapse of the bone area can be seen. In the later stage, the subchondral bone plate and articular surface collapse, bone contour change, stepped discontinuity, bone compression increase, while the acetabular articular surface is also damaged, joint space narrowing and bone redundancy formation. ②Isotope scan The diagnostic sensitivity of ischemic osteonecrosis is 80%, and it reflects the lesion earlier than conventional X-ray examination. ③CT examination CT has the characteristics of high resolution and accurate contrast, which can make the diagnosis of osteonecrosis earlier than X-ray film, with a sensitivity of 90% or more and high specificity. The CT manifestation of osteonecrosis: early stage shows normal or stellate structure deformation, thickening and disorder of weight-bearing bone trabeculae, limited cystic change sparse area and scattered speckled calcification area; middle and late stage shows bone contour deformation, fragmentation and marrow cavity sclerosis, etc. MRI examination is the most sensitive method for diagnosing osteonecrosis, which has the characteristics of ideal display of the morphology, structure and function of the skeletal system and is significantly better than X-ray, CT examination and isotope scan, when patients with predisposing factors are excluded early. ⑤ Others Such as bone hemodynamic examination, arteriography, and puncture biopsy are often helpful for the early diagnosis of osteonecrosis. The blood tests are often non-specific. For differential diagnosis, alkaline phosphatase, rheumatoid factor and blood sedimentation tests can be performed. 4.Our suggestion Pay attention to the relevant pathogenic triggers such as long-term alcoholism, application of hormones, the manifestation of clinical symptoms such as unexplained recurrent pain in the hip, limping, rest without relief, etc., do not need to be nervous, to regularly perform imaging examinations, timely consultation with experts, is the best way to detect and exclude osteonecrosis.