There are two main types of fracture repositioning criteria: first, anatomical repositioning, anatomical repositioning means that the fracture end is completely well aligned. Second, functional repositioning, functional repositioning means that although the fracture end is not restored to the anatomical relationship, it will not have a significant impact on the function of the limb after the fracture heals. The specific criteria are as follows: First, the rotational displacement, separation and displacement of the fracture site must be completely corrected. Second, the shortening displacement in the adult lower limb fracture cannot exceed 1 cm, and in children, if there is no epiphyseal injury, the lower limb shortening is within 2 cm. Thirdly, angular displacement, forward and backward, in line with the direction of joint activity, can be corrected later on by itself. If it is perpendicular to the direction of the joint, it cannot be corrected later and must be completely reset. Fourth, for transverse fractures of long bones, the alignment of the fracture end should be at least about 1/3, and the fracture of the epiphysis should be at least about 3/4.