After the growth of the bone scab, if it is subjected to large external force, it may be broken again. Generally 4~6 weeks after the fracture, the initial formation of bone scab, fracture healing process, bone scab is mainly composed of chondrocytes, vascular endothelial cells, etc., the strength of the normal bone tissue is poor, if this time there is an external force, which can lead to the bone scab again cracked. Three months after the fracture, at this time, the bone scab has become very strong, into the bone scab transformation molding period, bone growth at the fracture, if subjected to large external forces, can damage the formation of the bone scab, resulting in a second fracture. Generally, after half a year after the fracture surgery, the fracture has been healed, the internal fixation is taken out, the bone surface is left with screw holes, the strength of the bone decreases, the muscle at the fracture is broken, and the bone scab may be broken again. After the formation of bone scabs need to be regularly reviewed, and actively consult the doctor for treatment.