Preoperative Cannabis Use Did Not Increase Opioid Utilization After Primary Total Knee Arthroplasty in a Propensity Score-Matched Model

Background: Recreational and medicinal cannabis use is becoming increasingly popular, but there are little data on its effect on postoperative pain and opioid consumption after primary total knee arthroplasty (TKA). Purpose: We sought to evaluate the relationship between self-reported preoperative cannabis use and postoperative opioid consumption and post-discharge opioid prescriptions following elective primary TKA. Methods: We identified all patients who underwent unilateral, primary TKA for a diagnosis of osteoarthritis at a single institution between February 1, 2019, and April 30, 2021, and subdivided them into current cannabis users and non-users based on self-reported data. Regular users were propensity score-matched 1:6 with non-users using logistic regression on age, sex, body mass index (BMI), history of chronic pain, smoking status, history of anxiety/depression, American Society of Anesthesiology (ASA) classification, and type of anesthesia. Outcomes of interest included median inpatient (total, daily, and hourly) morphine milligram equivalents (MMEs), discharge MMEs, and outpatient MMEs within 90 days after surgery. Results: A cohort of 70 current cannabis users was matched with 420 non-users. There were no significant differences in opioid use in inpatient MMEs (hourly, daily, or total), discharge MMEs, or outpatient MMEs between cohorts. Also, there was no significant difference in hospital stay between cohorts. Conclusion: In this retrospective propensity score-matched model, preoperative cannabis use did not independently increase opioid use post-TKA in the inpatient or outpatient setting when compared with non-use. More rigorous, prospective study is warranted.