“…These cocktails have been shown to be effective in the acute perioperative period but have finite periods of action. Traditional amide local anesthetics such as bupivacaine or ropivacaine (which is reported to have a faster onset than bupivacaine but with a similar duration of action [2,7,11,12,22,25,37,41,50,52,55,58,74,86]) have been the mainstay of most TKA PAI cocktails. In addition to amide local anesthetics, some investigators have chosen to also include intrathecal morphine as part of their pain management protocol.…”