The main reasons for the numbness after sitting upright for a while three years after the operation of comminuted fracture of ankle bone are related to the unobstructed local blood circulation, traumatic inflammation or nerve injury. 1. Poor local blood circulation: comminuted fracture of ankle bone is a relatively serious injury, which is easy to be accompanied by damage to the surrounding tissues, such as blood vessels and soft tissue injuries. Three years after the operation, if there is a problem of poor local blood circulation, after sitting upright for a while, due to the obstruction of blood reflux, it is easy to cause numbness. 2. Traumatic inflammation: after comminuted fracture of ankle bone, local traumatic inflammation may be triggered. Three years after surgery, if you keep a posture for a long time, it is easy to cause local numbness, even with pain and swelling. 3. Nerve damage: if the comminuted fracture of ankle bone is accompanied by local peripheral nerve injury, it is easy to trigger the symptoms of nerve damage, such as local numbness. If the symptoms are serious and last for a long time, it may affect the function of the ankle joint, so it is necessary to check the cause of the disease and then carry out standardized treatment to prevent the symptoms from worsening in the later stage.