In preparation for the procedure, the skin of the knee is cleansed and sanitized. The injection sites are numbed with a local anesthetic. Using a fluoroscope (a type of x-ray device that shows video images from within the body), the physician carefully guides a needle to one of the targeted nerves. An anesthetic mixture is injected through this needle to numb the nerve. The physician repeats the injection at two more locations to numb three of the genicular nerves.