COX-1 x COX-2 x NMDA receptor x σ1 receptor

Total knee arthroplasty (TKA) is one of the most painful orthopedic procedures. After TKA surgery, postoperative pain relief may be achieved using a variety of techniques. Integral to recovery and improved outcomes is early ambulation and mobilization. Achieving adequate postoperative pain control while ensuring the ability to ambulate early can be quite challenging.
Currently, in our country there has been a call to address prescription opioid use and abuse due to a nationwide opioid epidemic. In light of this, improving our multimodal analgesic protocol will serve to decrease reliance of opioid medications for pain control. Multimodal analgesia is effective in decreasing total opioid consumption postoperatively. Dextromethorphan is a low-affinity noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist. It has a long history of clinical use with an established safety record. Studies have shown that it has a positive effect as an analgesic.
In order to see if dextromethorphan will decrease opioid use, this study will look at two patient groups undergoing total knee arthroplasty with the same preoperative, intraoperative, and postoperative anesthetic plan with the exception of the addition of dextromethorphan to one groups multimodal analgesic regimen. This study is designed as a double-blinded, randomized, prospective cohort trial.