Due to the slow onset of femoral head necrosis, easy to ignore the causes (such as hormones, etc.), atypical early localization symptoms and signs, and especially the lack of vigilance of doctors, many outpatients have been seen for several times or even for 2-3 months until the localization symptoms and signs appear and the femoral head has collapsed and deformed before being diagnosed. The three main symptoms of femoral head necrosis are pain in the hip joint (unilateral or bilateral), claudication, and functional impairment. Since the only symptom in the early stage is pain, it is often misdiagnosed as sciatica, lumbar disc bulge (prolapse), pear-shaped muscle syndrome, knee osteoarthritis, rheumatism, etc. Clinically, patients with low back pain, especially patients with posterior hip radicular pain and knee pain, often ignore hip disorders and conventional pelvic orthopantomographs that do not easily detect microscopic changes in X-rays, which are two common cases of femoral head necrosis misdiagnosis and missed diagnosis.