I am so sorry to hear that you had a tourniquet related injury. If it is a would it's usually due to chemical irritation from the antiseptic fluids they used to clean your knee before the surgery. Since it's like a burn injury it hurts really bad. With regular clean dressing of the wound and bandaging will lead to early healing. And then the pain will go away. On the other hand if the nerves in the leg have been affected, then the pain from the nerves may last for weeks before subsiding completely. In such a situation you may need medicines to keep the pain under control. You will have to visit your doctor to get the medicines. I cannot prescribe meds as Practo prohibits me from doing so. Wish you a speedy recovery!