Left distal radius fracture with cast finger black considering local blood vessel compression, the blood circulation of the finger is blocked, ischemic necrosis or bruising and swelling. Fracture of distal radius will generally cause local soft tissue swelling, if the cast is fixed at this time, the bandage is too tightly wound or locally given to swelling, can cause local blood vessels, especially arterial compression, resulting in obstruction of blood circulation in the finger area, there is ischemia, necrosis of the skin cells, black finger, accompanied by numbness of the finger. It is also possible that the veins are compressed, blood circulation is blocked, blood accumulates in the finger area, bruising occurs, and the finger becomes black and purple, accompanied by a feeling of local swelling. After the radial fracture plaster immobilization need to constantly observe the local finger color, physician-guided treatment.