Comparison of Two Periarticular Injection Medications for Adjunctive Pain Management Following Total Knee Arthroplasty (TKA)

Inclusion Criteria: All patients at least 18 years old who have primary unilateral TKA for osteoarthritis performed at Thomas Jefferson University Hospital. Exclusion Criteria: * American Society of Anesthesiologist (ASA) score of 4 or higher * Hepatic disease (contraindication for acetaminophen) * Renal disease (contraindication for NSAIDs) * Any contraindication for oxycodone, ketorolac, epinephrine, pregabalin, gabapentin, hydromorphone, Tramadol, morphine or other narcotics that are considered as part of routine postoperative pain control protocol * Fibromyalgia * Any contraindication for intrathecal opioid injection * History of substance abuse during the last 2 years * History of allergy to amide compounds * Current consumption of monoaminoxidase (MAO) inhibitors and tricyclic antidepressant (TCA) medications * Allergy to metabisulfite compounds * Chronic use of opioid medications in the month prior to surgery (leads to opioid tolerance and/or opioid-induced hyperalgesia) * Body weight\<50 Kg, BMI\>40 Kg/m2 * History of hypotension * Patients with any surgery related complication in the first 4-6 weeks following TKA, such as infection or mechanical failure