To those who have problems with the saw glitching out:
You doin't have to keep drinking whiskey. Once the game tells you to cut the leg, ONLY do that AND keep up your will to live (Space). I hav eliterally reached 0 health before and still completed the surgery bc my will to live was still up. If your will reaches 0, you die. As long as you keep hitting Space, you'll be fine and the saw should work as long as you don't stop cutting once you start.