A total of 256 patients undergoing TKA for primary osteoarthritis were randomized into one of six groups : a control group ( saline solution , epinephrine , and cefazolin , n = 42 ) , Group 1 ( ropivacaine , n = 43 ) , Group 2 ( ropivacaine + morphine , n = 43 ) , Group 3 ( ropivacaine + ketorolac , n = 42 ) , Group 4 ( ropivacaine + morphine + ketorolac , n = 43 ) , and Group 5 ( ropivacaine + morphine + ketorolac + methylprednisolone , n = 43 ) .