The blackening of the whole foot after foot fracture surgery may be caused by poor blood circulation, damage to the surrounding tissues and tissue necrosis. 1. Poor blood circulation: After foot fracture surgery, local blood circulation will be affected, and local bleeding may occur, forming bruises, which will be manifested as darkening and purpling of the foot. 2. Damage to surrounding tissues: after foot fracture surgery, the surrounding tissues of the foot will be damaged, resulting in skin pigmentation, causing changes in the skin of the foot, manifested as darkening of the entire foot. 3. Tissue necrosis: blood vessels and arteries may be damaged after foot fracture surgery, affecting blood circulation in the foot. Poor blood circulation will lead to tissue ischemia, which will lead to tissue necrosis, manifesting as blackening of the whole foot, accompanied by numbness of the foot and other symptoms. After foot fracture surgery, you should pay attention to rest and avoid walking on the ground too early. In the case of postoperative blackening of the foot, it is necessary to go to the hospital in time to consult a doctor to clarify the cause of the disease and then carry out targeted treatment.