80 patients undergoing unilateral total knee arthroplasty were randomized to receive an intra-operative intra-articular injection of either a combination of morphine, bupivacaine, and betamethasone, or an injection of saline solution. This study observed the effects on an intra-operative analgesia injection on post-operative pain and function. The results from this study indicated that the analgesia injection provided early reductions in pain when compared to the placebo group. There was also an improvement in early functional tests including time to straight leg raise and 90 degree flexion of the knee.