The cycle of femoral head necrosis varies from person to person or from cause to cause, because decompression sickness, such as that produced by divers during rapid ascent to the water surface, can occur in 1-2 years in severe cases. Application of hormones can also occur in 3-5 years, or even less. Due to the different sensitivity of human and human body, even if the same dose of hormones is applied, the cycle of necrosis is not the same, while large amount of hormones and long-term application of hormones will speed up the cycle of femoral head necrosis. With heavy alcohol consumption, exertion or bone neck fracture, the cycle is longer, 5-10 years or even longer before it appears. It is also related to the vascular damage at the time of injury, the amount of alcohol consumption and the individual’s physical condition.