60 patients scheduled for total knee arthroplasty were randomized to one of four groups to examine the effects of different combinations of tramadol and ropivacaine for femoral nerve block (FNB). Two intervention groups included the addition of either 100mg or 50mg tramadol to ropivacaine for FNB, while two control groups were treated with either ropivacaine without tramadol (0mg) for FNB, or no FNB. The purpose of this study was to evaluate if the addition of tramadol for FNB was associated with significantly better outcome measures relating to analgesia. Visual analog scale for pain scores at rest and on movement, sensory block time, and overall use of patient-controlled analgesia postoperatively were significantly better in the 100mg and 50mg tramadol groups compared to both the 0mg tramadol group and the no FNB group. It should be noted that patients receiving tramadol had significantly longer motor blockades.