After a fracture, fracture healing is divided into three main phases: the first phase is the hematoma mechanization phase, which mainly lasts 2-3 weeks. The second stage is the primary bone scab formation period, which generally takes 8-12 weeks. The third stage is the period of bone scab remodeling and shaping, which generally takes 1-2 years and is longer. In addition, fracture healing should be combined with clinical symptoms, combined with X-ray of the fracture end, no pressure pain at the fracture site, no abnormal activity, and bone scab growth on the X-ray of the fracture and continuous through the fracture end. Generally, for lower extremity fracture, it takes 4-8 weeks for cast fixation; for upper extremity fracture, it takes 4-6 weeks for cast fixation, removal of cast, and non-weight bearing functional exercise. The duration of full weight-bearing is about 8 weeks for the upper extremity and 12 weeks for the lower extremity.