More than 300,000 total knee joint replacement surgeries are performed per year in the United States and safe, effective management of post-operative pain in these patients, often elderly, deconditioned, obese, or with co-morbid diseases like sleep apnea, can be challenging and often require a multidisciplinary, multimodal approach. Opiates have been a mainstay of treatment in the post-operative period with varying degrees of success and complications. Inadequately controlled postoperative pain is not uncommon. Poorly controlled pain inhibits early mobilization and hinders post-operative physical therapy.