Cannabis Use Among Lower-Extremity Arthroplasty Patients Does Not Lead to Worse Postoperative Outcomes

Introduction: Smoking and general categorizations of substance use are linked with increased postoperative complications following total knee arthroplasty (TKA) and total hip arthroplasty (THA). There is a lack of similar evidence on how cannabis use may affect outcomes after arthroplasty. The present study aims to compare postoperative outcomes in cannabis users versus non-cannabis users who underwent THA/TKA. We hypothesize that cannabis users will have no difference in primarily the complication rate, revision rate, and secondarily post-operative Patient-Reported Outcomes Information System (PROMIS) scores, hospital stay, or pain compared to matched controls. Methods: Billing codes were used to generate lists of hip/knee arthroplasty patients from 2013 to 2019 at our institution. In the case group, cannabis use was confirmed via chart review. Cannabis-using patients were matched appropriately with non-users by (1) the same arthroplasty procedure; (2) BMI ± 3.5; (3) age ± 3 years; (4) sex. Data on postoperative outcomes were collected from charts and compared between groups using either a Chi-square test for qualitative variables or a paired t-test for quantitative variables. Results: A total of 24 patients with an average age of 57.1 and a BMI of 30.6 were confirmed to have isolated cannabis use. They were matched to 24 patients with an average age of 57.6 and a BMI of 31.4. There were no significant differences in the complication rate (4.2% vs 4.2%, p=1.00), the revision rate (0% vs 4.2%, p=0.31), days of hospital stay (2.7 vs 3.3, p=0.22), or postoperative pain (4.7 vs 4.9, p=0.86). Similarly, there were no significant differences in all PROMIS score measures. Discussion/conclusions: Current research shows that cannabis use may lead to increased revision arthroplasty and decreased mortality, with mixed findings regarding post-surgical complications. The present study suggests that cannabis-using patients have no difference in postoperative complication rate, revision rate, PROMIS scores, hospital stay, or pain compared to matched controls.