Clinical Research Directory

Inclusion Criteria: Participants * Adult patients older than 18 years old admitted to SRC for total shoulder and reverse total shoulder arthroplasty Nurses * The nurse who will administer acetaminophen to a study patient. Exclusion Criteria: Participants * Pregnant patient * Patients that cannot swallow pills or cannot take liquid (for example due to risk of aspiration) * Emergency surgery * Chronic pain * On home opioids, any other pain modulating medications including benzodiazepine, Neurontin, ketamine. * Past medical or social history of substance abuse disorder, including ethanol misuse disorder, marijuana misuse disorder * History of any psychiatric disorders including anxiety, depression, any cognitive dysfunction * Any patients who cannot provide informed consents on their own (those who would need Legally Authorized Representatives (LARs) or surrogates) * Liver dysfunction limiting amount of safe oral acetaminophen * baseline hyperbilirubinemia (ex: chronic liver disease, Gilbert's) * patients unable to take PO * Patients with neurologic, neuromuscular, or movement disorders unable to drink from a cup. Nurses * any nurse who is not involved in the direct care of a study patient, or who is not comfortable with setting up the PCA pump.