At HSS, most Achilles tendon surgeries are done with a nerve block (regional anesthesia) and/or a spinal anesthetic while you are in a twilight sleep. An anesthesiologist will perform the regional block in the operating room once you are asleep. This will numb your leg from the knee down and is done for pain control and comfort during and after the procedure. This a long-acting nerve block that may last 24 to 48 hours.