The cast is usually played once after the fracture occurs, and if the cast becomes loose after 1-2 weeks, it will need to be replaced once, and will not be replaced in general, and will need to be replaced once in about six weeks in special cases, as follows: 1. For most fractures, the cast can be fixed for 1-2 weeks after the fracture occurs. If the swelling subsides and the cast becomes loose, it can be replaced once and refixed to ensure the stability of the fracture end, and the cast will not be replaced until the fracture heals, until it is removed in about six weeks to avoid stiffness of the joints adjacent to the fixation. At this time, the fracture end is relatively stable and no further external fixation is needed, and functional exercises should be started to ensure fracture healing and soft tissue repair. 2. In special cases, such as fracture combined with Achilles tendon rupture, although the fracture can be kept stable in about six weeks, the Achilles tendon has not yet healed. Therefore, the cast cannot be removed at six weeks, but can be changed from a long leg cast to a short leg cast and continued to be fixed for two weeks. The cast can be removed at about eight weeks to ensure smooth healing of the Achilles tendon and also to promote normal healing of the fracture.