Cannabidiol for Postoperative Opioid Reduction in Primary Total Knee Arthroplasty

Inclusion Criteria: * Willing and able to read, understand, and sign the informed consent (English) * Willingness to participate in all study measures and restrictions, including patient-reported outcomes and longitudinal follow-up * Scheduled for surgery: primary total knee arthroplasty * Primary diagnosis of osteoarthritis of the surgical knee * Individuals of reproductive potential must agree to use acceptable birth control (defined in manual of operating procedures). This includes currently practicing an effective form of two types of birth control for women of childbearing potential, which are defined as those, alone or in combination, that result in a low failure rate (i.e., less than 1% per year) when used consistently and correctly from the screening visit until 28 days after the last study drug administration. * Participants must also agree not to donate sperm or eggs during study drug administration * Ability to take and to swallow the study medication and be willing to adhere to the treatment regimen * Agreement to adhere to Lifestyle Considerations (see protocol) throughout study duration Exclusion Criteria: * Revision or bilateral total knee arthroplasty * Individuals receiving or actively applying for worker's compensation or disability and other aspects associated with potential secondary gain (postoperative disability for recovery is permitted) * Severe physical impairment or clinically significant illness (e.g., blindness, paraplegia) * Co-morbid medical c…