Femoral head necrosis is the most serious long-term complication of femoral neck fracture. The femoral head is located in the joint capsule, and its blood supply mainly comes from the internal femoral artery system, the arterial system of the round ligament and the cervical ascending artery system from the arterial ring outside the joint capsule, among which the cervical ascending artery system plays a major role. When the femoral neck is fractured, the endosteal arterial system is definitely damaged, and the blood flow to the femoral head depends on the residual part of the cervical ascending arterial system and the round ligament arterial system, which still has blood supply, and the external injury may cause damage to the cervical ascending arterial vessels and increase the pressure of the accumulated blood in the joint capsule, affecting its blood supply. In other words, once the main vascular system is damaged, it is difficult for other blood supply systems to compensate, and the residual blood flow can hardly nourish the whole femoral head, which will lead to femoral head necrosis in the long run.