Due to the anatomical, biomechanical and local blood supply characteristics of femoral neck fractures, nonunion is a relatively common complication, and the general literature reports that the nonunion rate of femoral neck fractures is 7%-15%. The rate of nonunion of femoral neck fractures is the highest among the fractures of the extremities and has become a serious social problem especially with the aging of the population. The main reasons for non-union 1. Age: Most scholars believe that high age is a factor affecting fracture healing, and the non-union rate is 32% to 41% in foreign countries with the age of 75 as the boundary; 18% under 75. Therefore, the non-healing rate of patients above 75 years of age is significantly higher. 2, the degree of fracture displacement: the more severe the fracture displacement, the more difficult it is to heal, which is a recognized rule and is the most important factor affecting fracture healing. 3, fracture site: most people now believe that in addition to the basal fracture of the femoral neck, the rate of non-healing occurs in high subcapsular fractures alone. 4, fracture site comminution: comminuted fractures mostly occur on the posterior aspect of the femoral neck and are difficult to detect on X-rays before repositioning, mostly after repositioning, presenting a typical butterfly-shaped bone fragment in the lateral phase. In Garden III and IV fractures, the nonunion rate is 5% for mild comminution, 21.3% for moderate comminution, and 75% for severe comminution. Posterior edge comminution affects the sturdiness of internal fixation is also a factor. 5. Fracture line tilt: Regarding the clinical significance of Pauwell and Linton angle measurements, the current basis for determining fracture healing by fracture line tilt as a separate factor is inadequate. Fracture line inclination does not have a significant effect on fracture healing. 6, poor fracture repositioning: poor femoral neck fracture repositioning will prevent the reconstruction of head blood flow and reduce the contact between the distal and proximal ends of the fracture and the mechanical instability caused by fixation. 7, unreasonable fixation. 8, Premature unreasonable weight bearing. Clinical manifestations Pain of the affected hip is mostly not serious, weakness of the affected limb and afraid to bear weight, shortening of the affected limb, limited rotation of the lower limb, etc. X-ray examination: (1) the fracture line is clearly visible; (2) there are cystic changes in the bone on both sides of the fracture line; (3) in some patients, although the fracture line is invisible, the femoral neck is gradually absorbed and shortened during continuous filming, so that the internal fixation nail protrudes into the socket or the nail tail withdraws outward; (4) the femoral head is gradually dislocated, the femoral neck inversion angle gradually increases, and the neck stem angle becomes smaller. Surgical treatment Surgery is the main treatment method at present. The purpose of surgical treatment can be summarized as correction of the negative gravity line to eliminate or reduce the shear stress at the fracture end; internal fixation of the fracture and bone implant to enhance the regenerative repair ability of the bone; artificial joint replacement or other hip joint reconstruction to restore the function of the affected hip for weight-bearing walking. The patient’s age and general condition, the morphology of the femoral head and the degree of resorption of the femoral neck are the main bases for the choice of surgical method. In case of non-union, CT or MRI examination should be performed before reoperation to understand the blood flow of the femoral head. ②For young and middle-aged patients, bone flap graft with vascular tip plus internal fixation, external osteotomy between the ramus or osteotomy between the ramus and internal fixation again are feasible. ③For young patients with femoral head necrosis and non-collapsed femoral head, bone flap graft with vascular tip is feasible, and in case of non-collapsed femoral head, total hip arthroplasty should be performed.