Fracture healing is a continuous and gradual process, which can be generally divided into hematoma mechanization phase, primitive bone scab phase and bone scab transformation phase. With the activity and weight bearing of the limb, the scabs on the stress axis are continuously strengthened and remodeled, and the scabs outside the stress axis are gradually removed, so that the original scabs are gradually remodeled into permanent scabs, which have normal bone structure. The bone marrow cavity is also reconnected and the original shape of the bone is restored. Clinical healing of the fracture means that the external fixation can be removed and the function of the limb can be restored through functional exercises. The criteria of clinical healing of fracture: 1. no local pressure pain; 2. no local longitudinal percussion pain; 3. no local abnormal activities; 4. X-ray shows that the fracture line is blurred, and there is continuity of the bone through the fracture line; 5. after releasing the external fixation, the limb can withstand the following requirements: the upper limb is stretched forward flatly and holds the weight of 1kg up to one minute; lower limb is walking on the flat ground without the aid of crutches for 3 minutes and not less than 30 steps, and the fracture place is not deformed in 2 weeks of observation. Those who do not deform the fracture in 2 weeks of observation. Bone healing of fracture means that the bone has been restored or nearly restored to its original shape. Criteria of bone healing: 1. 5 criteria of clinical healing; 2. X-ray shows that the bone is passing through the fracture line, and the fracture line has disappeared or nearly disappeared. Simply put, clinical healing means that you can go for ex-fixation and exercise without crutches, but the strength of the healing is not yet normal, so you can’t do strenuous intensity exercise yet, or it will cause another fracture. Note: Various tests should be performed under the guidance of a specialist.