A total of @ patients undergoing TKA for primary osteoarthritis were randomized into one of six groups : a control group ( saline solution , epinephrine , and cefazolin , n = @ ) , Group @ ( ropivacaine , n = @ ) , Group @ ( ropivacaine + morphine , n = @ ) , Group @ ( ropivacaine + ketorolac , n = @ ) , Group @ ( ropivacaine + morphine + ketorolac , n = @ ) , and Group @ ( ropivacaine + morphine + ketorolac + methylprednisolone , n = @ ) .