Bone blackening refers to the occurrence of necrosis of the bone, for its blackening, the reasons are as follows: 1, infectious diseases: such as osteomyelitis, due to the local loss of blood supply to the bone, then the blackening, inactivation and other necrosis will occur. 2, open injuries: such as open fractures, there will be interruption of the blood supply to the fracture, if the free bone block is still put back into the body and not removed, then in the distant future will The local necrosis of the bone will appear, and the dead bone will be observed on the X-ray, that is, the density of the local bone is increased, and when the bone is cleared again, the dead bone will be found to present a blackened condition.