I have broken ankle. I had a surgery last week. Now my muscles just below the knee is turning blue. As if the blood is not getting to the tissues. Or burst vain?

Broken ankle. It is best to consult your surgeon for post operative questions. We are alway happy to make sure our post operative patients have no questions or concerns. .
Call and Ask. If you tissue is not getting any blood, believe me you would be in pain. Oxygen starved tissue can be unbearable. It would be wise to consult with your surgeon, you might even call the answering service. If the calf feels relatively as warm as the opposite calf, you are probably fine. I think that you may be seeing some extensive bruising moving through the tissue layers.