He has a piece of 'shrapnel' in his leg.
(..) So give her another shot! It could bring her into a coma. For Christ's sake, Olivia, she's going to kill herself down there! Go get the shot! I gotta get the shrapnel out of my ram. What? I have tweezers in my purse. David. Listen to me. I don't think a tranquilizer is gonna do shit. (..)2013 Evil Dead