Zynrelef Versus Adductor Canal Block

To compare postoperative MME consumption 72 hours after TKA in patients receiving intraoperative periarticular HTX-011 (Zynrelef) instillation versus adductor canal block.

Inclusion Criteria: * Patients \> 18 years of age * Patients undergoing primary, unilateral total knee arthroplasty * Ability to provide informed consent Exclusion Criteria: * Individuals under the age of 18 * Pregnant women * Prisoners * Adults unable to consent * American Society of Anesthesiologists Physical Status score greater than 3 * Patients taking any of the following medications before surgery: * Long-acting opioids within 3 days * Any opioids taken within 24 hours * Bupivacaine HCL within 5 days * Chronic opioid use or patients with known or suspected daily use of opioids for seven or more consecutive days within 6 months before their scheduled surgery * Illicit drug use determined by social history * Alcohol abuse determined by a CAGE Substance Abuse Screening Tool Score of at least two or greater * Patients with a known hypersensitivity (e.g., anaphylactic reactions and serious skin reactions) to any local anesthetic agent of the amide-type, NSAIDs, or to any of the other components of ZYNRELEF * Patients with a history of asthma, urticaria, or other allergic-type reactions after taking aspirin or other NSAIDs. Severe, sometimes fatal, anaphylactic reactions to NSAIDs have been reported in such patients