There are several reasons for delayed fracture healing: First, poor fracture alignment and alignment, such as when a fracture is not manipulated and the fracture severed end is displaced at an angle, or separated. With limited contact of the fracture severed ends, there will be slowed healing or delayed healing of the fracture. Second, because of the early fixation of the fracture, the degree of fixation is not stable enough, during the fixation of the fracture produced micro-movement, such as loose plaster, or premature walking when the plaster is fixed, can also cause poor healing of the fracture. Third, it is related to the site of fracture. In some parts of the body, such as lower tibia, lower middle section fracture or femoral neck fracture, the blood supply to the fracture site itself is less. Fractures in these areas are more likely to have delayed healing or non-healing and are prone to necrosis of the femoral head.