The most dangerous time for a fractured neck of femur should depend on the specific type of treatment, mostly around 2 to 5 weeks. Most femoral neck fractures occur as a result of direct or indirect external forces on the hip. If conservative treatment such as manipulative reduction is performed and a brace is given to immobilize the fracture, the most dangerous time is within 2 to 3 weeks after reduction. During this time, as the fracture has not yet reached bony healing, it is still in the stage of fibrous healing, and if there is activity, it is easy to cause displacement of the fracture. If surgical treatment such as internal fixation with hollow nail or total hip arthroplasty is adopted, it is more dangerous in 4~5 weeks after surgery. Attention needs to be paid to postoperative bed rest, which can easily lead to deep vein thrombosis of the lower limbs or symptoms such as joint ankylosis during this period. Therefore, postoperative functional activities should be carried out at an early stage under the guidance of the doctor, which can effectively avoid the occurrence of comorbidities.