There are a lot of middle-aged and elderly people who have symptoms of coldness and fear of cold in the lower extremities, but most of them do not draw attention to it. Many people think that the coldness and fear of cold in the lower extremities may be due to cold and wind chill, and so does Zhou Yi, which brings him great pain. Zhou Yi is a construction worker, in order to pay for his son to go to college, he often worked overtime, working overnight, only three or four hours of sleep a day, a long time, the symptoms of lower limb fear of cold. However, he did not care, thought it was cold, wear a few more clothes, more covers at night can be, but the symptoms did not change, after a few months also appeared after the lower limb pain, walking difficulties. Later, when his son found out about it, he hurriedly took him to the hospital for a checkup and was finally diagnosed with exertional femoral head necrosis. It was only then that he realized that the coldness in his lower limbs was caused by early stage osteonecrosis. People do not understand what the relationship between lower extremity coldness and osteonecrosis is. The coldness of the lower extremities in femoral head necrosis is related to the ischemia of the femoral head, but not all blood flow is blocked. When the blood supply to the femoral head is reduced to a certain level, the bone cells of the femoral head will wither and die. During the gradual decrease of blood supply to the femoral head, the femoral head itself does not show any painful symptoms. However, as the blood supply around the femoral head gradually decreases, and the hip joint area is the upper end of the blood supply to the lower extremity, when this upper end becomes obstructed, its lower end will inevitably experience a slowing of blood flow at the same time. The lack of blood supply to the lower extremities, the muscles are easily fatigued and weak when moving, while the lower extremities reduce the temperature brought by blood circulation, and fear of cold. Therefore, I hope that people who often drink alcohol, people who engage in heavy physical strength, and people who use hormone drugs for a long time must pay great attention to the symptoms of coldness and fear of coldness in the lower limbs, so as not to cause osteonecrosis of the femoral head because of momentary carelessness.