Most likely the climate will do any necessary pruning for you. If they are chopped down, and the weather seems good to the tubers, they will resprout anyways until they chose to go dormant.

Last time I was able to dig, I saw sprouts coming to about two inches from the surface, where the tip was blackened by the freezing temps about the soil. I am in zone 5, with light snow on the ground. My bet is that there is not too much growth down below the last couple weeks. ;-)