The goal of this clinical trial is to learn if oral methadone given before surgery works to minimize post-operative pain and opioid usage. The main questions it aims to answer are:

Does oral methadone improve post-operative pain scores as compared to standard treatment? Does oral methadone lead to reduced use of post-operative and post-discharge opioid usage as compared to the current standard treatment?

Researchers will compare oral methadone to a placebo (a look-alike substance that contains no drug) to assess the questions above.

Participants will:

Receive either oral methadone or a look-alike placebo before surgery Receive standard intraoperative and immediate post-operative pain control at the anesthesiologist's discretion Be asked about their pain levels in the recovery area Keep a diary of pain and opioid usage over the first 2 days after surgery

STUDY METHOD We plan to perform a double-blinded randomized control study, where the participants, anesthesiologist, data collectors, and study team will be unaware of the intervention offered. Participants will be randomly assigned to the control group (standard intraoperative pain control using short-acting opioids, with drug choice and dosing at the practitioner's discretion) or to the intervention group (a single dose of perioperative oral methadone).

Patients will be recruited and consented to whether they want to participate in the study by a member of the team during a pre-operative clinic visit (Anesthesia START clinic or orthopedic surgery clinic) or on day-of-surgery in the pre-op holding area.

Participants will be randomized to either the control group or treatment group using randomization software. Participants assigned to the intervention group will receive a single dose of oral methadone will be administered in the pre-operative holding area. Dosing will be weight dependent, using 0.15mg/kg ideal body weight (IBW) as a reference; participants weighing less than 50kg will receive 5mg oral methadone, while participants weighing more than 50kg will receive 10mg oral methadone. Participants assigned to the control group will receive an identical-looking placebo sugar pill. A study pharmacist will deliver the appropriate pill to the patient or pre-op nurse in the pre-op holding area on the day of surgery.

Pre-operatively, all participants will complete a survey collecting data on visual analog scale (VAS) pain scores for the 2 weeks leading up to surgery, whether this is different from their baseline pain score at home (if applicable), and pre-operative opioid usage (if applicable). All participants will receive standard-of-care pre-operative non-opioid medications as determined by the orthopedic surgical team if needed.

Intraoperatively, participants will receive either GA or monitored anesthesia care, at the discretion of the anesthesia care team.

In the post-anesthesia acute care unit (PACU), all participants will receive standard PACU medications (ie. intravenous dilaudid or oral oxycodone, and acetaminophen as needed) for pain relief. Pain scores on a 1-10 scale and amount of opioid usage will be collected per standard PACU protocol upon arrival, after 30 minutes, and after 60 minutes. Post-discharge, all participants will receive oxycodone-acetaminophen for at-home pain (as standardized by the orthopedic surgery team) to be used as needed for breakthrough pain refractory to acetaminophen/ibuprofen, or in patients where these medications are contraindicated.

Following discharge, a member of the study team will call participants on post-operative day 1 and post-operative day 2 to assess pain scores and opioid usage. Participants will also be discharged with a pain diary to assist in documenting endpoints. They will also be asked to document any complications or adverse events at each of these time intervals.

Once the data collection is complete, we will perform statistics (detailed below) to determine if there is any significant difference. The primary outcome will be post-discharge opioid usage, and the secondary outcome will be patient-perceived pain scores at the time intervals above.

STRATIFICATION/DESCRIPTIVE FACTORS/RANDOMIZATION SCHEME

Participants will not be stratified prior to randomization.

Descriptive factors: age, gender, BMI will be looked to assess for possible confounding variables, but will not affect group assignment.

The website randomizer.org will assist in our randomization of participants enrolled in the study. The software randomly determines which participant will be assigned to Control vs Treatment group in a 1:1 ratio. At the onset of the study, we will create a predetermined randomization list (containing study participant code and treatment arm assignment), and provide it to the study pharmacist who will then be the only one with access to this linked info. The study pharmacist will be informed of the new enrollment and will read back the study code to the team member, who will record it in a separate data collection form that contains link between Medical Record Number and participant code. The pharmacist will strike out the participant code on their sheet to keep track of used codes, then prepare the appropriate medication and deliver it to the participant or pre-op nurse in the pre-op holding area on the day of surgery.

Inclusion Criteria:

• medically optimized participants who will undergo elective arthroscopic knee or hip repair

Exclusion Criteria:

• pregnant or breastfeeding, age under 18, history of respiratory compromise, allergy to opioids, recipient of pre-operative nerve block